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Find video protocols related to scientific articles indexed in Pubmed.
CAMK2N1 inhibits prostate cancer progression through androgen receptor-dependent signaling.
Oncotarget
PUBLISHED: 10-10-2014
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Castration resistance is a major obstacle to hormonal therapy for prostate cancer patients. Although androgen independence of prostate cancer growth is a known contributing factor to endocrine resistance, the mechanism of androgen receptor deregulation in endocrine resistance is still poorly understood. Herein, the CAMK2N1 was shown to contribute to the human prostate cancer cell growth and survival through AR-dependent signaling. Reduced expression of CAMK2N1 was correlated to recurrence-free survival of prostate cancer patients with high levels of AR expression in their tumor. CAMK2N1 and AR signaling form an auto-regulatory negative feedback loop: CAMK2N1 expression was down-regulated by AR activation; while CAMK2N1 inhibited AR expression and transactivation through CAMKII and AKT pathways. Knockdown of CAMK2N1 in prostate cancer cells alleviated Casodex inhibition of cell growth, while re-expression of CAMK2N1 in castration-resistant cells sensitized the cells to Casodex treatment. Taken together, our findings suggest that CAMK2N1 plays a tumor suppressive role and serves as a crucial determinant of the resistance of prostate cancer to endocrine therapies.
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Safety and efficacy of neratinib in combination with capecitabine in patients with metastatic human epidermal growth factor receptor 2-positive breast cancer.
J. Clin. Oncol.
PUBLISHED: 10-06-2014
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Neratinib is a potent irreversible pan-tyrosine kinase inhibitor with antitumor activity and acceptable tolerability in patients with human epidermal growth factor receptor 2 (HER2) -positive breast cancer. A multinational, open-label, phase I/II trial was conducted to determine the maximum-tolerated dose (MTD) of neratinib plus capecitabine in patients with solid tumors (part one) and to evaluate the safety and efficacy of neratinib plus capecitabine in patients with HER2-positive metastatic breast cancer (part two).
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Densovirus Is a Mutualistic Symbiont of a Global Crop Pest (Helicoverpa armigera) and Protects against a Baculovirus and Bt Biopesticide.
PLoS Pathog.
PUBLISHED: 10-01-2014
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Mutualistic associations between symbiotic bacteria and their hosts are common within insect systems. However, viruses are often considered as pathogens even though some have been reported to be beneficial to their hosts. Herein, we report a novel densovirus, Helicoverpa armigera densovirus-1 (HaDNV-1) that appears to be beneficial to its host. HaDNV-1 was found to be widespread in wild populations of H. armigera adults (>67% prevalence between 2008 and 2012). In wild larval populations, there was a clear negative interaction between HaDNV-1 and H. armigera nucleopolyhedrovirus (HaNPV), a baculovirus that is widely used as a biopesticide. Laboratory bioassays revealed that larvae hosting HaDNV-1 had significantly enhanced resistance to HaNPV (and lower viral loads), and that resistance to Bacillus thuringiensis (Bt) toxin was also higher at low doses. Laboratory assays indicated that the virus was mainly distributed in the fat body, and could be both horizontally- and vertically-transmitted, though the former occurred only at large challenge doses. Densovirus-positive individuals developed more quickly and had higher fecundity than uninfected insects. We found no evidence for a negative effect of HaDNV-1 infection on H. armigera fitness-related traits, strongly suggesting a mutualistic interaction between the cotton bollworm and its densovirus.
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Seasonal migration of Apolygus lucorum (Hemiptera: Miridae) over the Bohai Sea in northern China.
J. Econ. Entomol.
PUBLISHED: 09-09-2014
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During the past decade, Apolygus lucorum (Meyer-Dür) has become a key pest on cotton in northern China. Whether or not this species is a migrant, and if so, what pattern of seasonal migration this species exhibits remains unknown. The combination of searchlight trapping and radar observation on an isolated island in the center of Bohai Gulf during the past 11 yr provided direct evidence that both male and female A. lucorum adults migrate at least 40-60 km (and probably much greater distances) across the Bohai Gulf waters. There were considerable yearly and monthly variation in the number of A. lucorum trapped on BH, and the migration period during 2009-2013 ranged from 102 to 154 d. A. lucorum adults had downwind displacement rather than randomly by heading toward their seasonally favorable directions, which toward the east-northeast in summer, but south-southwest (SSW) in early autumn. The vast majority of adults flying at airspeeds 0.5-2.5 m/s and at altitudes < 150 m above ground level. Most of trapped females were virgins with little or no ovarian development, as suggests that the onset of migration is initiated mainly by sexually immature individuals, which is termed the "oogenesis-flight syndrome." Such findings reveal a new route for A. lucorum movements northward to and southward from the northeastern agricultural region of China, which will help us develop more effective management strategies against this pest species.
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Mis-splicing of the ABCC2 gene linked with Bt toxin resistance in Helicoverpa armigera.
Sci Rep
PUBLISHED: 08-26-2014
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Toxins from the bacterium Bacillus thuringiensis (Bt) are used widely for insect control in sprays and transgenic plants, but their efficacy is reduced when pests evolve resistance. Previous work showed that mutations in a gene encoding the transporter protein ABCC2 are linked with resistance to Bt toxins Cry1Ab, Cry1Ac or both in four species of Lepidoptera. Here we compared the ABCC2 gene of Helicoverpa armigera (HaABCC2) between susceptible strains and a laboratory-selected strain with >1,000-fold resistance to Cry1Ac relative its susceptible parent strain. We discovered a 73-base pair (bp) insertion in the cDNA of the resistant strain that generates a premature stop codon expected to yield a truncated ABCC2 protein. Sequencing of genomic DNA revealed that this insertion is an intron that is not spliced out because of a 6-bp deletion at its splicing site. Analysis of progeny from crosses revealed tight genetic linkage between HaABCC2 and resistance to Cry1Ac. These results provide the first evidence that mis-splicing of a gene encoding an ABCC2 protein confers resistance to a Bt toxin.
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Acquisition of Cry1Ac protein by non-target arthropods in Bt soybean fields.
PLoS ONE
PUBLISHED: 08-11-2014
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Soybean tissue and arthropods were collected in Bt soybean fields in China at different times during the growing season to investigate the exposure of arthropods to the plant-produced Cry1Ac toxin and the transmission of the toxin within the food web. Samples from 52 arthropod species/taxa belonging to 42 families in 10 orders were analysed for their Cry1Ac content using enzyme-linked immunosorbent assay (ELISA). Among the 22 species/taxa for which three samples were analysed, toxin concentration was highest in the grasshopper Atractomorpha sinensis and represented about 50% of the concentration in soybean leaves. Other species/taxa did not contain detectable toxin or contained a concentration that was between 1 and 10% of that detected in leaves. These Cry1Ac-positive arthropods included a number of mesophyll-feeding Hemiptera, a cicadellid, a curculionid beetle and, among the predators, a thomisid spider and an unidentified predatory bug belonging to the Anthocoridae. Within an arthropod species/taxon, the Cry1Ac content sometimes varied between life stages (nymphs/larvae vs. adults) and sampling dates (before, during, and after flowering). Our study is the first to provide information on Cry1Ac-expression levels in soybean plants and Cry1Ac concentrations in non-target arthropods in Chinese soybean fields. The data will be useful for assessing the risk of non-target arthropod exposure to Cry1Ac in soybean.
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DACH1 inhibits cyclin D1 expression, cellular proliferation and tumor growth of renal cancer cells.
J Hematol Oncol
PUBLISHED: 07-24-2014
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BackgroundRenal cell carcinoma (RCC) is a complex with diverse biological characteristics and distinct molecular signature. New target therapies to molecules that drive RCC initiation and progression have achieved promising responses in some patients, but the total effective rate is still far from satisfaction. Dachshund (DACH1) network is a key signaling pathway for kidney development and has recently been identified as a tumor suppressor in several cancer types. However, its role in renal cell carcinoma has not been fully investigated.MethodsImmunohistochemical staining for DACH1, PCNA and cyclin D1 was performed on human renal tissue microaraays and correlation with clinic-pathological characteristics was analyzed. In vitro proliferation, apoptosis and in vivo tumor growth were evaluated on human renal cancer cell lines with decitabine treatment or ectopic expression of DACH1. Downstream targets and potential molecular mechanism were investigated through western blot, immunoprecipitation and reporter gene assays.ResultsExpression of DACH1 was significantly decreased in human renal carcinoma tissue. DACH1 protein abundance was inversely correlated with the expression of PCNA and cyclin D1, tumor grade, and TNM stage. Restoration of DACH1 function in renal clear cell cancer cells inhibited in vitro cellular proliferation, S phase progression, clone formation, and in vivo tumor growth. In mechanism,DACH1 repressed cyclin D1 transcription through association with AP-1 protein.ConclusionOur results indicated that DACH1 was a novel molecular marker of RCC and it attributed to the malignant behavior of renal cancer cells. Re-activation of DACH1 may represent a potential therapeutic strategy.
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Seasonal migration of Ctenoplusia agnata (Lepidoptera: Noctuidae) over the Bohai Sea in northern China.
J. Econ. Entomol.
PUBLISHED: 07-17-2014
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Ctenoplusia agnata (Staudinger) (Lepidoptera: Noctuidae) is an important polyphagous pest in East Asia. Previous studies showed that C. agnata moths possesses the potential to undertake long-distance migration; however, knowledge of whether or not the migration of C. agnata moths is a regular ecological behavior and what the pattern of seasonal migrations is in case of regular migration is currently lacking. In the current study, systemic monitoring of population dynamics of C. agnata was conducted by a searchlight trap on an island in the center of Bohai gulf in northern China, during 2003-2013. Our results provided strong evidence for the hypothesis that C. agnata is one of the pest species undertaking regular high altitude long-distance migration and we have depicted the seasonal migration pattern over the Bohai Sea. The first capture of C. agnata generally appeared in late April and early May, then the daily number of catches increased to high levels in late July and formed two waves of migration through August and early September, and finally, the moths disappeared in late October. The mean time from the earliest trapping to the latest trapping within a year was 141.0 +/- 3.0 days. The index of ovarian development of female C. agnata showed seasonal variability and suggested that its migratory flight may be independent of the degree of ovarian development and mating status. In addition, strong migration events took place in 2003, 2004, 2008, and 2010 (annual sum of catches > 10,000). The research result from this work is helpful for understanding the occurrence regularity of C. agnata and developing an integrated pest management strategy.
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Does Athetis lepigone moth (Lepidoptera: Noctuidae) take a long-distance migration?
J. Econ. Entomol.
PUBLISHED: 07-17-2014
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Athetis lepigone (Möschler), a new lepidopteran pest in China, has spread quickly to seven provinces since it was first reported causing damage on summer maize in Hebei province in 2005, Whether this species is a migrant or not remains unknown. The past 3 yr searchlight trapping on an island in the center of Bohai Gulf provided direct evidence that both male and female A. lepigone moths migrate across the Bohai Gulf waters in northern China because no host crops or A. lepigone larvae were found on this island. The four migration waves observed in this study represent high-altitude movements of the overwintering, first, second, and third generations of A. lepigone moths, respectively. Carbon isotope analysis showed that 1.76-5.44% of the tested A. lepigone moths originated from C4 plants, which provides additional evidence that this species is a migrant because there are no C4 plants on this small island. The 89.24-96.89% of tested A. lepigone moths originated from C3 plants were significantly higher than that from C4 plants in all generations, suggesting that maize fields are not the main host sites for A. lepigone. Few females were trapped in spring and early summer with relatively high mating frequency and more advanced ovarian development, suggesting that the migration of this species is not completely bound by the "oogenesis-flight syndrome." These findings reveal a new route for A. lepigone migrating to and from the northeastern agricultural region of China, and improve our knowledge of the migration ecology of A. lepigone. Further studies are needed to clarify the migration trajectories that will help in developing sound forecasting systems for this pest species.
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Arthropod abundance and diversity in transgenic bt soybean.
Environ. Entomol.
PUBLISHED: 06-09-2014
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Before the commercialization of any insect-resistant genetically modified crop, it must be subjected to a rigorous premarket risk assessment. Here, possible effects of growing of transgenic Cry1Ac soybean on arthropod communities under field conditions were assessed for 2 yr and quantified in terms of arthropod community indices including the Shannon-Weaver diversity index, richness index, and dominance index. Our results showed no significant differences of diversity, richness, or dominant indices for Bt soybean compared with the recipient cultivar, conventional soybean, or sprayed conventional soybean. Conventional soybean treatment with insecticide had an adverse effect on the arthropod community after spraying, but arthropod community diversity recovered quickly. Bt soybean had no negative effect on the dominant distribution of subcommunities, including sucking pests, other pests, predators, parasitoids, and others except for lepidopteran pests. The dominance distribution of lepidopteran pests decreased significantly in Bt soybean because of the significant decrease in the numbers of Spodoptera litura (F.) and Ascotis selenaria Schiffermüller et Denis compared with the recipient cultivar. Our results showed that there were no negative effects of Cry1Ac soybean on the arthropod community in soybean field plots in the short term.
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Epigenetic silencing of DACH1 induces the invasion and metastasis of gastric cancer by activating TGF-? signalling.
J. Cell. Mol. Med.
PUBLISHED: 04-23-2014
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Gastric cancer (GC) is the fourth most common malignancy in males and the fifth most common malignancy in females worldwide. DACH1 is frequently methylated in hepatic and colorectal cancer. To further understand the regulation and mechanism of DACH1 in GC, eight GC cell lines, eight cases of normal gastric mucosa, 98 cases of primary GC and 50 cases of adjacent non-tumour tissues were examined. Methylation-specific PCR, western blot, transwell assay and xenograft mice were used in this study. Loss of DACH1 expression correlated with promoter region methylation in GC cells, and re-expression was induced by 5-Aza-2'-deoxyazacytidine. DACH1 is methylated in 63.3% (62/98) of primary GC and 38% (19/50) of adjacent non-tumour tissues, while no methylation was found in normal gastric mucosa. Methylation of DACH1 correlated with reduced expression of DACH1 (P < 0.01), late tumour stage (stage III/IV) (P < 0.01) and lymph node metastasis (P < 0.05). DACH1 expression inhibited epithelial-mesenchymal transition and metastasis by inhibiting transforming growth factor (TGF)-? signalling and suppressed GC cell proliferation through inducing G2/M phase arrest. The tumour size is smaller in DACH1-expressed BGC823 cell xenograft mice than in unexpressed group (P < 0.01). Restoration of DACH1 expression also sensitized GC cells to docetaxel. These studies suggest that DACH1 is frequently methylated in human GC and expression of DACH1 was controlled by promoter region methylation. DACH1 suppresses GC proliferation, invasion and metastasis by inhibiting TGF-? signalling pathways both in vitro and in vivo. Epigenetic silencing DACH1 may induce GC cells' resistance to docetaxel.
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Monitoring cotton bollworm resistance to Cry1Ac in two counties of northern China during 2009-2013.
Pest Manag. Sci.
PUBLISHED: 04-12-2014
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Transgenic cotton that expresses a gene derived from the bacterium Bacillus thuringiensis (Bt) has been deployed for combating cotton bollworm in China since 1997. As a follow-up on research started in 2002, the quantitative shifts in larval Cry1Ac resistance of field Helicoverpa armigera populations were monitored from 2009-2013 using bioassays of isofemale lines.
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Quantitative analysis of fitness costs associated with the development of resistance to the Bt toxin Cry1Ac in Helicoverpa armigera.
Sci Rep
PUBLISHED: 03-31-2014
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Transgenic Bacillus thuringiensis (Bt) crops play an increasing role in pest control, and resistance management is a major issue in large-scale cultivation of Bt crops. The fitness cost of resistance in targeted pests is considered to be one of the main factors delaying resistance when using the refuge strategy. By comparing 10 resistant Helicoverpa armigera (Hubner) strains, showing various resistance levels to Bt toxin (Cry1Ac), to a susceptible strain, we showed an increasing fitness cost corresponding with increasing levels of resistance. The relationship between overall fitness cost C and the resistance ratio Rr could be described by C = 24.47/(1 + exp([1.57 - Log10Rr]/0.2)). This model predicted that the maximum overall fitness cost would be ~24% (± 5.22) in the strains with the highest resistance level. The overall fitness cost was closely linked to egg hatching rate, fecundity, emergence rate, larval survival rate, and developmental duration of adults. Among fitness components measured, fecundity was the most sensitive trait linked to the resistance selection. To integrate the results into simulation models would be valuable in evaluating how variation in fitness cost may influence the development of resistance in pest populations, thus helping to develop enhanced refuge strategies.
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High methane natural gas/air explosion characteristics in confined vessel.
J. Hazard. Mater.
PUBLISHED: 03-26-2014
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The explosion characteristics of high methane fraction natural gas were investigated in a constant volume combustion vessel at different initial conditions. Results show that with the increase of initial pressure, the peak explosion pressure, the maximum rate of pressure rise increase due to a higher amount (mass) of flammable mixture, which delivers an increased amount of heat. The increased total flame duration and flame development time result as a consequence of the higher amount of flammable mixture. With the increase of the initial temperature, the peak explosion pressures decrease, but the pressure increase during combustion is accelerated, which indicates a faster flame speed and heat release rate. The maximum value of the explosion pressure, the maximum rate of pressure rise, the minimum total combustion duration and the minimum flame development time is observed when the equivalence ratio of the mixture is 1.1. Additionally, for higher methane fraction natural gas, the explosion pressure and the maximum rate of pressure rise are slightly decreased, while the combustion duration is postponed. The combustion phasing is empirically correlated with the experimental parameters with good fitting performance. Furthermore, the addition of dilute gas significantly reduces the explosion pressure, the maximum rate of pressure rise and postpones the flame development and this flame retarding effect of carbon dioxide is stronger than that of nitrogen.
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Does expression of Bt toxin matter in farmer's pesticide use?
Plant Biotechnol. J.
PUBLISHED: 02-12-2014
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Despite the widespread adoption of Bt cotton, farmers still spray excessive pesticides in their cotton fields. In contrast to scientists who always use high quality seeds in the laboratory and/or experimental fields, farmers may plant low quality seeds with a low expression of Bt toxin. How does the expression of Bt toxin influence farmers' pesticide use? On the basis of a plot-level survey and laboratory test data, this study shows that pesticide use on one cotton plot is influenced not only by the expression of Bt crops in this plot, but also by the average expression in the village in the early stage of the cotton growing season. In other words, high expression of Bt toxin benefits not only the farmers who plant the varieties but also all the other villagers.
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Effect of farm management practices in the Bt toxin production by Bt cotton: evidence from farm fields in China.
Transgenic Res.
PUBLISHED: 01-21-2014
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Based on farm field plot level survey data and laboratory test, we examine the determinants of the expression of Bt toxin in China's Bt cotton production. The results show that the expression of Bt toxin differs significantly among varieties. Even for the same variety the expression of Bt toxin also varies substantially among villages and among farmers in the same village. Econometric analyses show that after controlling for the effects of varieties and locations (or villages), farm management, particular applications of phosphate and potash fertilizers, and manure, has significant positive effects on Bt toxin expression in farmer's fields. In contrast to previous studies which showed that nitrogen fertilizer has a positive impact on expression of Bt toxin, this study shows that nitrogen fertilizer has no significant impact on expression of Bt toxin in farmer's fields. On the other hand, the expression of Bt toxin has a positive relationship with phosphate fertilizer, potash fertilizer and manure application.
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Biosafety management and commercial use of genetically modified crops in China.
Plant Cell Rep.
PUBLISHED: 01-03-2014
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As a developing country with relatively limited arable land, China is making great efforts for development and use of genetically modified (GM) crops to boost agricultural productivity. Many GM crop varieties have been developed in China in recent years; in particular, China is playing a leading role in development of insect-resistant GM rice lines. To ensure the safe use of GM crops, biosafety risk assessments are required as an important part of the regulatory oversight of such products. With over 20 years of nationwide promotion of agricultural biotechnology, a relatively well-developed regulatory system for risk assessment and management of GM plants has been developed that establishes a firm basis for safe use of GM crops. So far, a total of seven GM crops involving ten events have been approved for commercial planting, and 5 GM crops with a total of 37 events have been approved for import as processing material in China. However, currently only insect-resistant Bt cotton and disease-resistant papaya have been commercially planted on a large scale. The planting of Bt cotton and disease-resistant papaya have provided efficient protection against cotton bollworms and Papaya ringspot virus (PRSV), respectively. As a consequence, chemical application to these crops has been significantly reduced, enhancing farm income while reducing human and non-target organism exposure to toxic chemicals. This article provides useful information for the colleagues, in particular for them whose mother tongue is not Chinese, to clearly understand the biosafety regulation and commercial use of genetically modified crops in China.
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Plant volatile analogues strengthen attractiveness to insect.
PLoS ONE
PUBLISHED: 01-01-2014
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Green leaf bug Apolygus lucorum (Meyer-Dür) is one of the major pests in agriculture. Management of A. lucorum was largely achieved by using pesticides. However, the increasing population of A. lucorum since growing Bt cotton widely and the increased awareness of ecoenvironment and agricultural product safety makes their population-control very challenging. Therefore this study was conducted to explore a novel ecological approach, synthetic plant volatile analogues, to manage the pest. Here, plant volatile analogues were first designed and synthesized by combining the bioactive components of ?-ionone and benzaldehyde. The stabilities of ?-ionone, benzaldehyde and analogue 3 g were tested. The electroantennogram (EAG) responses of A. lucorum adult antennae to the analogues were recorded. And the behavior assay and filed experiment were also conducted. In this study, thirteen analogues were acquired. The analogue 3 g was demonstrated to be more stable than ?-ionone and benzaldehyde in the environment. Many of the analogues elicited EAG responses, and the EAG response values to 3 g remained unchanged during seven-day period. 3 g was also demonstrated to be attractive to A. lucorum adults in the laboratory behavior experiment and in the field. Its attractiveness persisted longer than ?-ionone and benzaldehyde. This indicated that 3 g can strengthen attractiveness to insect and has potential as an attractant. Our results suggest that synthetic plant volatile analogues can strengthen attractiveness to insect. This is the first published study about synthetic plant volatile analogues that have the potential to be used in pest control. Our results will support a new ecological approach to pest control and it will be helpful to ecoenvironment and agricultural product safety.
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Silencing DACH1 promotes esophageal cancer growth by inhibiting TGF-? signaling.
PLoS ONE
PUBLISHED: 01-01-2014
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Human Dachshund homologue 1 (DACH1) is a major component of the Retinal Determination Gene Network. Loss of DACH1 expression was found in breast, prostate, lung, endometrial, colorectal and hepatocellular carcinoma. To explore the expression, regulation and function of DACH1 in human esophageal cancer, 11 esophageal cancer cell lines, 10 cases of normal esophageal mucosa, 51 cases of different grades of dysplasia and 104 cases of primary esophageal squamous cancer were employed. Methylation specific PCR, immunohistochemistry, western blot, flow cytometry, small interfering RNAs, colony formation techniques and xenograft mice model were used. We found that DACH1 expression was regulated by promoter region hypermethylation in esophageal cancer cell lines. 18.8% (6 of 32) of grade 1, 42.1% (8 of 19) of grade 2 and grade 3 dysplasia (ED2,3), and 61.5% (64 of 104) of esophageal cancer were methylated, but no methylation was found in 10 cases of normal esophageal mucosa. The methylation was increased in progression tendency during esophageal carcinogenesis (P<0.01). DACH1 methylation was associated with poor differentiation (P<0.05) and late tumor stage (P<0.05). Restoration of DACH1 expression inhibited cell growth and activated TGF-? signaling in KYSE150 and KYSE510 cells. DACH1 suppressed human esophageal cancer cell tumor growth in xenograft mice. In conclusion, DACH1 is frequently methylated in human esophageal cancer and methylation of DACH1 is involved in the early stage of esophageal carcinogenesis. DACH1 expression is regulated by promoter region hypermethylation. DACH1 suppresses esophageal cancer growth by activating TGF-? signaling.
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Use of a pollen-based diet to expose the ladybird beetle Propylea japonica to insecticidal proteins.
PLoS ONE
PUBLISHED: 01-01-2014
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A rape seed pollen-based diet was developed and found to be suitable for use in a dietary exposure assay for Propylea japonica. Using the diet, we established and validated a dietary exposure assay by using the protease inhibitor E-64 as positive control. Dose-dependent responses were documented for all observed life-table parameters of P. japonica including survival, pupation and eclosion rates, development time and adult weight. Results suggested that the dietary assay can detect the effects of insecticidal compounds on the survival and development of P. japonica. Using the established dietary assay, we subsequently tested the toxicity of Cry1Ab, Cry1Ac and Cry1F proteins that are expressed by transgenic maize, cotton or rice plants to P. japonica larvae. The diet containing E-64 was included as a positive control. Survival and development of P. japonica larvae were not adversely affected when the diet contained purified Cry1Ab, Cry1Ac, or Cry1F at 500 µg/g diet representing a worst-case exposure scenario. In contrast, P. japonica larvae were adversely affected when the diet contained E-64. The bioactivity and stability of the Cry proteins in the diet and Cry protein uptake by the ladybird larvae were confirmed by bioassay with a Cry-sensitive insect species and by ELISA. The current study describes a suitable experimental system for assessing the potential effects of gut-active insecticidal compounds on ladybird beetle larvae. The experiments with the Cry proteins demonstrate that P. japonica larvae are not sensitive to Cry1Ab, Cry1Ac and Cry1F.
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Cell Fate Factor DACH1 Represses YB-1-mediated Oncogenic Transcription and Translation.
Cancer Res.
PUBLISHED: 12-12-2013
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The epithelial-mesenchymal transition (EMT) enhances cellular invasiveness and confers tumor cells with cancer stem cell like characteristics, through transcriptional and translational mechanisms. The mechanisms maintaining transcriptional and translational repression of EMT and cellular invasion are poorly understood. Herein, the cell fate-determination factor Dachshund (DACH1), suppressed EMT via repression of cytoplasmic translational induction of Snail by inactivating the Y box-binding protein (YB-1). In the nucleus, DACH1 antagonized YB-1-mediated oncogenic transcriptional modules governing cell invasion. DACH1 blocked YB-1-induced mammary tumor growth and EMT in mice. In basal-like breast cancer (BLBC) the reduced expression of DACH1 and increased YB-1, correlated with poor metastasis free survival. The loss of DACH1 suppression of both cytoplasmic translational and nuclear transcriptional events governing EMT and tumor invasion may contribute to poor prognosis in basal-like forms of breast cancer, a relatively aggressive disease subtype.
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Randomized Phase III Trial of Temsirolimus and Bevacizumab Versus Interferon Alfa and Bevacizumab in Metastatic Renal Cell Carcinoma: INTORACT Trial.
J. Clin. Oncol.
PUBLISHED: 12-02-2013
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To prospectively determine the efficacy of combination therapy with temsirolimus plus bevacizumab versus interferon alfa (IFN) plus bevacizumab in metastatic renal cell carcinoma (mRCC).
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Epigenetic regulation of DACH1, a novel Wnt signaling component in colorectal cancer.
Epigenetics
PUBLISHED: 10-22-2013
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Colorectal cancer (CRC) is one of the common malignant tumors worldwide. Both genetic and epigenetic changes are regarded as important factors of colorectal carcinogenesis. Loss of DACH1 expression was found in breast, prostate, and endometrial cancer. To analyze the regulation and function of DACH1 in CRC, 5 colorectal cancer cell lines, 8 cases of normal mucosa, 15 cases of polyps and 100 cases of primary CRC were employed in this study. In CRC cell lines, loss of DACH1 expression was correlated with promoter region hypermethylation, and re-expression of DACH1 was induced by 5-Aza-2-deoxyazacytidine treatment. We found that DACH1 was frequently methylated in primary CRC and this methylation was associated with reduction in DACH1 expression. These results suggest that DACH1 expression is regulated by promoter region hypermethylation in CRC. DACH1 methylation was associated with late tumor stage, poor differentiation, and lymph node metastasis. Re-expression of DACH1 reduced TCF/LEF luciferase reporter activity and inhibited the expression of Wnt signaling downstream targets (c-Myc and cyclinD1). In xenografts of HCT116 cells in which DACH1 was re-expressed, tumor size was smaller than in controls. In addition, restoration of DACH1 expression induced G2/M phase arrest and sensitized HCT116 cells to docetaxel. DACH1 suppresses CRC growth by inhibiting Wnt signaling both in vitro and in vivo. Silencing of DACH1 expression caused resistance of CRC cells to docetaxel. In conclusion, DACH1 is frequently methylated in human CRC and methylation of DACH1 may serve as detective and prognostic marker in CRC.
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Combination of plant and insect eggs as food sources facilitates ovarian development in an omnivorous bug Apolygus lucorum (Hemiptera: Miridae).
J. Econ. Entomol.
PUBLISHED: 07-20-2013
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Diet nutrient is considered as an important regulatory factor for reproduction of insects. To understand the effect of different food sources on the reproductive physiology of Apolygus lucorum (Meyer-Dür), the ovarian development in adult females was investigated when they were fed on green beans (Gb), combination of green beans Phaseolus vulgaris L and Helicoverpa armigera eggs (GbHe), or H. armigera eggs (He). A female of A. lucorum has two ovaries, and each ovary contained seven yellowish ovarioles. Females fed on Gb or GbHe had larger ovaries and the ovarioles contained larger numbers of oocytes compared with those fed on He. Females in GeHe treatment has significantly higher number of follicles per ovary throughout the whole adult period compared with those in Gb or He treatment. Furthermore, the length of the best developed ovariole was affected by the diet type. The females fed on GbHe had the most developed ovarioles, with significantly longer ovarioles than those fed on Gb or He. A method was described to quantitatively score the degree of ovarian development in the current study. Similarly, the ovarian development scores were significantly higher for females in GbHe treatment than those in other two diet treatments. The ovarian development significantly delayed for females fed on He. Our results demonstrate that A. lucorum, as an omnivorous insect species, can acquire nutrients from both plant and animal origin food sources, and the combination of plants and animal food sources can significantly facilitate the ovary development of its females.
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A phase two randomised trial of neratinib monotherapy versus lapatinib plus capecitabine combination therapy in patients with HER2+ advanced breast cancer.
Eur. J. Cancer
PUBLISHED: 07-04-2013
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The safety and efficacy of neratinib monotherapy were compared with that of lapatinib plus capecitabine in patients with human epidermal growth factor receptor-2-positive (HER2+), locally advanced/metastatic breast cancer and prior trastuzumab treatment.
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Acetylation of the cell-fate factor dachshund determines p53 binding and signaling modules in breast cancer.
Oncotarget
PUBLISHED: 06-27-2013
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Breast cancer is a leading form of cancer in the world. The Drosophila Dac gene was cloned as an inhibitor of the hyperactive epidermal growth factor (EGFR), ellipse. Herein, endogenous DACH1 co-localized with p53 in a nuclear, extranucleolar compartment and bound to p53 in human breast cancer cell lines, p53 and DACH1 bound common genes in Chip-Seq. Full inhibition of breast cancer contact-independent growth by DACH1 required p53. The p53 breast cancer mutants R248Q and R273H, evaded DACH1 binding. DACH1 phosphorylation at serine residue (S439) inhibited p53 binding and phosphorylation at p53 amino-terminal sites (S15, S20) enhanced DACH1 binding. DACH1 binding to p53 was inhibited by NAD-dependent deacetylation via DACH1 K628. DACH1 repressed p21CIP1 and induced RAD51, an association found in basal breast cancer. DACH1 inhibits breast cancer cellular growth in an NAD and p53-dependent manner through direct protein-protein association.
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Cyclin D1 induction of Dicer governs microRNA processing and expression in breast cancer.
Nat Commun
PUBLISHED: 06-14-2013
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Cyclin D1 encodes the regulatory subunit of a holoenzyme that phosphorylates the pRB protein and promotes G1/S cell-cycle progression and oncogenesis. Dicer is a central regulator of miRNA maturation, encoding an enzyme that cleaves double-stranded RNA or stem-loop-stem RNA into 20-25 nucleotide long small RNA, governing sequence-specific gene silencing and heterochromatin methylation. The mechanism by which the cell cycle directly controls the non-coding genome is poorly understood. Here we show that cyclin D1(-/-) cells are defective in pre-miRNA processing which is restored by cyclin D1a rescue. Cyclin D1 induces Dicer expression in vitro and in vivo. Dicer is transcriptionally targeted by cyclin D1, via a cdk-independent mechanism. Cyclin D1 and Dicer expression significantly correlates in luminal A and basal-like subtypes of human breast cancer. Cyclin D1 and Dicer maintain heterochromatic histone modification (Tri-m-H3K9). Cyclin D1-mediated cellular proliferation and migration is Dicer-dependent. We conclude that cyclin D1 induction of Dicer coordinates microRNA biogenesis.
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EYA1 phosphatase function is essential to drive breast cancer cell proliferation through cyclin D1.
Cancer Res.
PUBLISHED: 05-01-2013
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The Drosophila Eyes Absent Homologue 1 (EYA1) is a component of the retinal determination gene network and serves as an H2AX phosphatase. The cyclin D1 gene encodes the regulatory subunits of a holoenzyme that phosphorylates and inactivates the pRb protein. Herein, comparison with normal breast showed that EYA1 is overexpressed with cyclin D1 in luminal B breast cancer subtype. EYA1 enhanced breast tumor growth in mice in vivo, requiring the phosphatase domain. EYA1 enhanced cellular proliferation, inhibited apoptosis, and induced contact-independent growth and cyclin D1 abundance. The induction of cellular proliferation and cyclin D1 abundance, but not apoptosis, was dependent upon the EYA1 phosphatase domain. The EYA1-mediated transcriptional induction of cyclin D1 occurred via the AP-1-binding site at -953 and required the EYA1 phosphatase function. The AP-1 mutation did not affect SIX1-dependent activation of cyclin D1. EYA1 was recruited in the context of local chromatin to the cyclin D1 AP-1 site. The EYA1 phosphatase function determined the recruitment of CBP, RNA polymerase II, and acetylation of H3K9 at the cyclin D1 gene AP-1 site regulatory region in the context of local chromatin. The EYA1 phosphatase regulates cell-cycle control via transcriptional complex formation at the cyclin D1 promoter.
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Dachshund binds p53 to block the growth of lung adenocarcinoma cells.
Cancer Res.
PUBLISHED: 03-14-2013
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Hyperactive EGF receptor (EGFR) and mutant p53 are common genetic abnormalities driving the progression of non-small cell lung cancer (NSCLC), the leading cause of cancer deaths in the world. The Drosophila gene Dachshund (Dac) was originally cloned as an inhibitor of hyperactive EGFR alleles. Given the importance of EGFR signaling in lung cancer etiology, we examined the role of DACH1 expression in lung cancer development. DACH1 protein and mRNA expression was reduced in human NSCLC. Reexpression of DACH1 reduced NSCLC colony formation and tumor growth in vivo via p53. Endogenous DACH1 colocalized with p53 in a nuclear, extranucleolar location, and shared occupancy of -15% of p53-bound genes in ChIP sequencing. The C-terminus of DACH1 was necessary for direct p53 binding, contributing to the inhibition of colony formation and cell-cycle arrest. Expression of the stem cell factor SOX2 was repressed by DACH1, and SOX2 expression was inversely correlated with DACH1 in NSCLC. We conclude that DACH1 binds p53 to inhibit NSCLC cellular growth.
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Assessment of potential sublethal effects of various insecticides on key biological traits of the tobacco whitefly, Bemisia tabaci.
Int. J. Biol. Sci.
PUBLISHED: 02-20-2013
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The tobacco whitefly Bemisia tabaci is one of the most devastating pests worldwide. Current management of B. tabaci relies upon the frequent applications of insecticides. In addition to direct mortality by typical acute toxicity (lethal effect), insecticides may also impair various key biological traits of the exposed insects through physiological and behavioral sublethal effects. Identifying and characterizing such effects could be crucial for understanding the global effects of insecticides on the pest and therefore for optimizing its management in the crops. We assessed the effects of sublethal and low-lethal concentrations of four widely used insecticides on the fecundity, honeydew excretion and feeding behavior of B. tabaci adults. The probing activity of the whiteflies feeding on treated cotton seedlings was recorded by an Electrical Penetration Graph (EPG). The results showed that imidacloprid and bifenthrin caused a reduction in phloem feeding even at sublethal concentrations. In addition, the honeydew excretions and fecundity levels of adults feeding on leaf discs treated with these concentrations were significantly lower than the untreated ones. While, sublethal concentrations of chlorpyrifos and carbosulfan did not affect feeding behavior, honeydew excretion and fecundity of the whitefly. We demonstrated an antifeedant effect of the imidacloprid and bifenthrin on B. tabaci, whereas behavioral changes in adults feeding on leaves treated with chlorpyrifos and carbosulfan were more likely caused by the direct effects of the insecticides on the insects nervous system itself. Our results show that aside from the lethal effect, the sublethal concentration of imidacloprid and bifenthrin impairs the phloem feeding, i.e. the most important feeding trait in a plant protection perspective. Indeed, this antifeedant property would give these insecticides potential to control insect pests indirectly. Therefore, the behavioral effects of sublethal concentrations of imidacloprid and bifenthrin may play an important role in the control of whitefly pests by increasing the toxicity persistence in treated crops.
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Expression of Cry1Ac in transgenic Bt soybean lines and their efficiency in controlling lepidopteran pests.
Pest Manag. Sci.
PUBLISHED: 02-08-2013
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BACKGROUND: Two transgenic lines of the soybean Glycine max, MON87701 expressing the Cry1Ac protein and MON87701RR2Y expressing Cry1Ac?+? EPSPS proteins, were evaluated for their resistance to four lepidopteran pests in the laboratory using detached-leaf bioassays throughout the soybean growth seasons (before anthesis, during anthesis and after anthesis) in China. Enzyme-linked immunosorbent assays (ELISAs) were used to monitor the Cry1Ac expression in soybean leaves. RESULTS: The bioassay results revealed that both transgenic soybean lines exhibited significantly high resistance against Helicoverpa armigera (Hübner) throughout the soybean growing seasons. The survival rates of H. armigera larvae ranged from 5.4 to 24.4% when feeding on the transgenic soybean leaves, significantly lower than the survival rates when feeding on control leaves (71.1-94.9%). Limited resistance was found for both transgenic soybean lines against Spodoptera litura (Fabricius), although the survival rates and weight of S. litura larvae as well as female fecundity were significantly decreased when feeding on Bt soybean leaves compared with feeding on control leaves. In contrast, both transgenic soybean lines provided almost no resistance to Spodoptera exigua (Hübner) and Agrotis ypsilon (Rottemberg). Cry1Ac expression in the leaves of both transgenic soybean lines was relatively stable throughout the soybean growing season, with a peak occurring at V6 -8 and V11 -12 before anthesis. The ELISA results were positively correlated with the results from the insect bioassays. CONCLUSIONS: The results show that, while Cry1Ac-expressing Bt soybeans may provide good protection against H. armigera, alternative control measures are required to manage S. exigua, S. litura and A. ypsilon. © 2013 Society of Chemical Industry.
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Epigenetic silencing of DACH1 induces loss of transforming growth factor-?1 antiproliferative response in human hepatocellular carcinoma.
Hepatology
PUBLISHED: 01-20-2013
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Human dachshund homolog 1 (DACH1) is a major component of the Retinal Determination Gene Network (RDGN) and functions as a tumor suppressor. However, the regulation of DACH1 expression and its function in hepatocellular carcinoma (HCC) remain unclear. In this study, epigenetic changes of DACH1 were analyzed in HCC cell lines and primary cancers. We found that promoter region hypermethylation was correlated with loss or reduction of DACH1 expression, and restoration of DACH1 expression was induced by 5-aza-2-deoxycytidine (5-AZA) in HCC cell lines. Promoter region methylation was found in 42% of primary HCC. Reduced expression of DACH1 was associated with poor differentiation of HCC nodules and higher serum aspartate aminotransferase/alanine aminotransferase ratio. DACH1 suppressed cellular growth by reactivating transforming growth factor beta (TGF-?) signaling. Ectopic expression of DACH1 enhanced chemosensitivity to 5-fluorouracil (5-FU) by inducing p21 expression in HCC cells. Conclusion: DACH1 is frequently methylated in HCC and DACH1 expression is regulated by promoter hypermethylation. Down-regulation of DACH1 is a novel mechanism for gaining resistance to the antiproliferative signaling of TGF-?1 and 5-FU resistance. (Hepatology 2013; 58:2012-2022).
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The evolution and expression of the moth visual opsin family.
PLoS ONE
PUBLISHED: 01-01-2013
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Because visual genes likely evolved in response to their ambient photic environment, the dichotomy between closely related nocturnal moths and diurnal butterflies forms an ideal basis for investigating their evolution. To investigate whether the visual genes of moths are associated with nocturnal dim-light environments or not, we cloned long-wavelength (R), blue (B) and ultraviolet (UV) opsin genes from 12 species of wild-captured moths and examined their evolutionary functions. Strong purifying selection appeared to constrain the functions of the genes. Dark-treatment altered the levels of mRNA expression in Helicoverpa armigera such that R and UV opsins were up-regulated after dark-treatment, the latter faster than the former. In contrast, B opsins were not significantly up-regulated. Diel changes of opsin mRNA levels in both wild-captured and lab-reared individuals showed no significant fluctuation within the same group. However, the former group had significantly elevated levels of expression compared with the latter. Consequently, environmental conditions appeared to affect the patterns of expression. These findings and the proportional expression of opsins suggested that moths potentially possessed color vision and the visual system played a more important role in the ecology of moths than previously appreciated. This aspect did not differ much from that of diurnal butterflies.
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Preference of a polyphagous mirid bug, Apolygus lucorum (Meyer-Dür) for flowering host plants.
PLoS ONE
PUBLISHED: 01-01-2013
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Apolygus lucorum (Meyer-Dür) (Hemiptera: Miridae) is one of the most important herbivores in a broad range of cultivated plants, including cotton, cereals, vegetables, and fruit crops in China. In this manuscript, we report on a 6-year long study in which (adult) A. lucorum abundance was recorded on 174 plant species from 39 families from early July to mid-September. Through the study period per year, the proportion of flowering plants exploited by adult A. lucorum was significantly greater than that of non-flowering plants. For a given plant species, A. lucorum adults reached peak abundance at the flowering stage, when the plant had the greatest attraction to the adults. More specifically, mean adult abundance on 26 species of major host plants and their relative standard attraction were 10.3-28.9 times and 9.3-19.5 times higher at flowering stage than during non-flowering periods, respectively. Among all the tested species, A. lucorum adults switched food plants according to the succession of flowering plant species. In early July, A. lucorum adults preferred some plant species in bloom, such as Vigna radiata, Gossypium hirsutum, Helianthus annuus and Chrysanthemum coronarium; since late July, adults dispersed into other flowering hosts (e.g. Ricinus communis, Impatiens balsamina, Humulus scandens, Ocimum basilicum, Agastache rugosus and Coriandrum sativum); in early September, they largely migrated to flowering Artemisia spp. (e.g. A. argyi, A. lavandulaefolia, A. annua and A. scoparia). Our findings underscore the important role of flowering plays in the population dynamics and inter-plant migration of this mirid bug. Also, our work helps understand evolutionary aspects of host plant use in polyphagous insects such as A. lucorum, and provides baseline information for the development of sustainable management strategies of this key agricultural pest.
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The endosymbiont Arsenophonus is widespread in soybean aphid, Aphis glycines, but does not provide protection from parasitoids or a fungal pathogen.
PLoS ONE
PUBLISHED: 01-01-2013
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Aphids commonly harbor bacterial facultative symbionts that have a variety of effects upon their aphid hosts, including defense against hymenopteran parasitoids and fungal pathogens. The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is infected with the symbiont Arsenophonus sp., which has an unknown role in its aphid host. Our research goals were to document the infection frequency and diversity of the symbiont in field-collected soybean aphids, and to determine whether Arsenophonus is defending soybean aphid against natural enemies. We performed diagnostic PCR and sequenced four Arsenophonus genes in soybean aphids from their native and introduced range to estimate infection frequency and genetic diversity, and found that Arsenophonus infection is highly prevalent and genetically uniform. To evaluate the defensive role of Arsenophonus, we cured two aphid genotypes of their natural Arsenophonus infection through ampicillin microinjection, resulting in infected and uninfected isolines within the same genetic background. These isolines were subjected to parasitoid assays using a recently introduced biological control agent, Binodoxys communis [Braconidae], a naturally recruited parasitoid, Aphelinus certus [Aphelinidae], and a commercially available biological control agent, Aphidius colemani [Braconidae]. We also assayed the effect of the common aphid fungal pathogen, Pandora neoaphidis (Remaudiere & Hennebert) Humber (Entomophthorales: Entomophthoraceae), on the same aphid isolines. We did not find differences in successful parasitism for any of the parasitoid species, nor did we find differences in P. neoaphidis infection between our treatments. Our conclusion is that Arsenophonus does not defend its soybean aphid host against these major parasitoid and fungal natural enemies.
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Seasonal expression of Bt proteins in transgenic rice lines and the resistance against Asiatic rice borer Chilo suppressalis (Walker).
Environ. Entomol.
PUBLISHED: 10-14-2011
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Laboratory bioassays and field surveys were carried out to compare the resistance of three transgenic rice (Oryza sativa L.) lines including Bt-DL expressing a single gene cry1Ab, Bt-KF6 expressing stacked genes cry1Ac and CpTI genes and Bt-SY63 expressing a fusion gene cry1Ab/cry1Ac, respectively, to an important rice pest Chilo suppressalis (Walker). In addition, enzyme-linked immunosorbent assays (ELISA) were conducted to monitor the Bt protein expressions in rice leaves and stems at different rice growth stages. Results showed that all the transgenic rice lines exhibited significantly high resistance to the pest compared with their corresponding nontransformed isolines. Among the transgenic rice lines, Bt-SY63 and Bt-KF6 had higher resistance to C. suppressalis at early growth stage, but lower resistance at late stages, while the pest resistance of Bt-DL was relatively stable throughout the growing season. The results were consistent with ELISA results showing that Bt protein levels in Bt-SY63 or Bt-KF6 leaves decreased in late growth stages, but were relatively stable in Bt-DL at all growth stages. This demonstrates that the resistance to a pest by Bt plants is positively correlated with Cry protein expression levels in plant tissues. Compared with Bt-SY63 and Bt-KF6, the Bt protein expression levels were significantly lower in Bt-DL, while its resistance to C. suppressalis was the highest. This may suggest that C. suppressalis is more susceptible to Cry1Ab than to Cry1Ac. The data from the current study are valuable for decision-making for commercial use of Bt rice lines and development of appropriate pest control and resistance management strategies for the transgenic rice lines.
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Sublethal effects of imidacloprid on Bemisia tabaci (Hemiptera: Aleyrodidae) under laboratory conditions.
J. Econ. Entomol.
PUBLISHED: 07-09-2011
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The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), is one of the most important pests in tropical and subtropical agriculture and is a key pest in greenhouse production worldwide. Current management of B. tabaci relies upon frequent applications of insecticides. Insecticide use not only directly affects pest populations through acute toxicity but also has indirect (sublethal) effects on pest physiology or behavior. In this study, we described sublethal effects of imidacloprid on adult feeding, immature development, adult fecundity, and F1 development of B. tabaci. Honeydew excretion of adults feeding on leaves treated with LC20 and LC40 concentration was significantly lower than that on untreated leaf discs. Egg production of B. tabaci adults subject to LC20 and LC40 concentrations also was less than untreated individuals. Upon transfer to untreated leaves, honeydew excretion and egg production recovered well within 24 and 48 h, respectively. Exposure to LC20 and LC40 concentrations significantly affected developmental time of B. tabaci eggs and nymphs, whereas it did not affect adult molting rate. We did not find sublethal effects on longevity and fecundity of B. tabaci adults when exposed to LC90 and LC40 concentrations for 24 h, and on egg hatching rate, nymphal mortality, and molting rate of the subsequent F1 generation. Exposure to imidacloprid at LC40 concentration significantly decreased the number of females in the F1 generation. Imidacloprid negatively affects development and reproduction of exposed individuals, and sex ratio of subsequent (F1) generation of B. tabaci, which probably disrupts B. tabaci population dynamics, slows population increase, and reduces infestation levels. Therefore, it is necessary to consider potential impact from imidacloprid for integrated management of the pest.
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The type 1 insulin-like growth factor receptor and resistance to DACH1.
Cell Cycle
PUBLISHED: 06-15-2011
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The mammalian homolog of the Drosophila dachshund gene (DACH1) has been reported as a tumor suppressor in human breast and prostate cancers. It downregulates the epidermal growth factor receptor (EGFR) and cyclin D1. The signaling pathway of the type 1 insulin-like growth factor receptor (IGF-IR) is known to be responsible for the development of resistance to treatment of human cancer with antibodies to the EGFR. We have asked whether DACH1 still exerts its tumor suppressor activity in cells dependent on the IGF-IR for growth. We find that in cells growing in IGF-1 (and unresponsive to EGF), DACH1 is devoid of tumor suppressor activity.
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Flight mill performance of the lacewing Chrysoperla sinica (Neuroptera: Chrysopidae) as a function of age, temperature, and relative humidity.
J. Econ. Entomol.
PUBLISHED: 03-17-2011
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The lacewing Chrysoperla sinica (Tjeder) (Neuroptera: Chrysopidae) is an important predator of several insect pests in China and has considerable potential as a biological control agent. An inoculative approach would be the releasing adults early in the season to ensure that populations are present before pest densities increase. However, an understanding of adult flight activity under different conditions is necessary to develop appropriate release strategies. Therefore, we used a 32-channel, computer-monitored flight mill system to determine the effect of age on the flight activity of unmated female and male adults. Both sexes had high total flight activity levels as well as the longest individual flight bouts 2 and 3 d after emergence. The effects of temperature (between 13 and 33 degrees C at 75% RH) and relative humidity (between 30 and 90% RH at 23 degrees C) on the flight activity of 3-d-old unmated adults also were determined. Flight activity declined at the lowest (13 degrees C) and highest (33 degrees C) temperatures tested, as well as at the lowest relative humidity (30% RH). These findings are discussed within the context of selecting the appropriate environmental conditions for releasing C. sinica.
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Construction and analysis of cDNA libraries from the antennae of male and female cotton bollworms Helicoverpa armigera (Hübner) and expression analysis of putative odorant-binding protein genes.
Biochem. Biophys. Res. Commun.
PUBLISHED: 02-25-2011
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Two high-quality cDNA libraries were constructed from female and male antennae of the cotton bollworm Helicoverpa armigera (Hübner). The titers were approximately 2.0 × 10? pfu/ml for females and 2.3 × 10? pfu/ml for males, and this complies with the test requirement. From the libraries, 1750 male ESTs and 1640 female ESTs were sequenced and further analyzed. We identified 15 olfactory genes (12 are new), and 14 of them have the characteristic six conserved cysteine residues. With the exception of OBP9, all the genes were classified as classical OBP genes. By alignment and cluster analysis, the 14 classical OBPs were divided into pheromone binding protein (PBP) genes, odorant binding protein (OBP) genes, general odorant binding protein 1 (GOBP1) genes, general odorant binding protein 2 (GOBP2) genes and antennae binding protein (ABP) genes. Among these genes, we obtained three PBP genes (PBP1-PBP3) including two new PBP genes, one new ABP gene, nine new OBP genes (OBP1-OBP9), one known GOBP1 gene and one known GOBP2 gene. Furthermore, the expression patterns of these 14 classical OBP genes were investigated in various tissues by real-time quantitative polymerase chain reaction (qPCR). The results indicated that some OBP genes are expressed differently in different sexes and tissues, but most of them are highly expressed in antennae.
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Reduced levels of membrane-bound alkaline phosphatase are common to lepidopteran strains resistant to Cry toxins from Bacillus thuringiensis.
PLoS ONE
PUBLISHED: 01-29-2011
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Development of insect resistance is one of the main concerns with the use of transgenic crops expressing Cry toxins from the bacterium Bacillus thuringiensis. Identification of biomarkers would assist in the development of sensitive DNA-based methods to monitor evolution of resistance to Bt toxins in natural populations. We report on the proteomic and genomic detection of reduced levels of midgut membrane-bound alkaline phosphatase (mALP) as a common feature in strains of Cry-resistant Heliothis virescens, Helicoverpa armigera and Spodoptera frugiperda when compared to susceptible larvae. Reduced levels of H. virescens mALP protein (HvmALP) were detected by two dimensional differential in-gel electrophoresis (2D-DIGE) analysis in Cry-resistant compared to susceptible larvae, further supported by alkaline phosphatase activity assays and Western blotting. Through quantitative real-time polymerase chain reaction (qRT-PCR) we demonstrate that the reduction in HvmALP protein levels in resistant larvae are the result of reduced transcript amounts. Similar reductions in ALP activity and mALP transcript levels were also detected for a Cry1Ac-resistant strain of H. armigera and field-derived strains of S. frugiperda resistant to Cry1Fa. Considering the unique resistance and cross-resistance phenotypes of the insect strains used in this work, our data suggest that reduced mALP expression should be targeted for development of effective biomarkers for resistance to Cry toxins in lepidopteran pests.
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Transcription elongation regulator 1 is a co-integrator of the cell fate determination factor Dachshund homolog 1.
J. Biol. Chem.
PUBLISHED: 10-18-2010
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DACH1 (Dachshund homolog 1) is a key component of the retinal determination gene network and regulates gene expression either indirectly as a co-integrator or through direct DNA binding. The current studies were conducted to understand, at a higher level of resolution, the mechanisms governing DACH1-mediated transcriptional repression via DNA sequence-specific binding. DACH1 repressed gene transcription driven by the DACH1-responsive element (DRE). Recent genome-wide ChIP-Seq analysis demonstrated DACH1 binding sites co-localized with Forkhead protein (FOX) binding sites. Herein, DACH1 repressed, whereas FOX proteins enhanced, both DRE and FOXA-responsive element-driven gene expression. Reduced DACH1 expression using a shRNA approach enhanced FOX protein activity. As DACH1 antagonized FOX target gene expression and attenuated FOX signaling, we sought to identify limiting co-integrator proteins governing DACH1 signaling. Proteomic analysis identified transcription elongation regulator 1 (TCERG1) as the transcriptional co-regulator of DACH1 activity. The FF2 domain of TCERG1 was required for DACH1 binding, and the deletion of FF2 abolished DACH1 trans-repression function. The carboxyl terminus of DACH1 was necessary and sufficient for TCERG1 binding. Thus, DACH1 represses gene transcription through direct DNA binding to the promoter region of target genes by recruiting the transcriptional co-regulator, TCERG1.
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Cell fate determination factor Dachshund reprograms breast cancer stem cell function.
J. Biol. Chem.
PUBLISHED: 10-11-2010
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The cell fate determination factor Dachshund was cloned as a dominant inhibitor of the hyperactive epidermal growth factor receptor ellipse. The expression of Dachshund is lost in human breast cancer associated with poor prognosis. Breast tumor-initiating cells (TIC) may contribute to tumor progression and therapy resistance. Here, endogenous DACH1 was reduced in breast cancer cell lines with high expression of TIC markers and in patient samples of the basal breast cancer phenotype. Re-expression of DACH1 reduced new tumor formation in serial transplantations in vivo, reduced mammosphere formation, and reduced the proportion of CD44(high)/CD24(low) breast tumor cells. Conversely, lentiviral shRNA to DACH1 increased the breast (B)TIC population. Genome-wide expression studies of mammary tumors demonstrated DACH1 repressed a molecular signature associated with stem cells (SOX2, Nanog, and KLF4) and genome-wide ChIP-seq analysis identified DACH1 binding to the promoter of the Nanog, KLF4, and Lin28 genes. KLF4/c-Myc and Oct4/Sox2 antagonized DACH1 repression of BTIC. Mechanistic studies demonstrated DACH1 directly repressed the Nanog and Sox2 promoters via a conserved domain. Endogenous DACH1 regulates BTIC in vitro and in vivo.
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Frequency of Bt resistance alleles in Helicoverpa armigera in the Xinjiang cotton-planting region of China.
Environ. Entomol.
PUBLISHED: 10-01-2010
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Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) is a key insect pest of cotton in Xinjiang cotton-planting region of northwest China. In this region, cotton is grown on average ? 1.65 million ha (1.53 ? 1.80 million ha) annually in largely monoculture agricultural landscapes, similarly to cropping systems in the United States or Australia. Under such cropping regimes, naturally occurring refuges (with non-Bt crops) may be insufficient to prevent H. armigera resistance development to Bt toxins. Therefore, we assessed frequency of alleles conferring resistance to Cry1Ac toxin of F(1) and F(2) offspring of H. armigera isofemale lines from two distinct localities in the region during 2005-2009. More specifically, a total of 224 isofemale lines was collected from Korla County (? 70% Bt cotton adoption) and 402 lines from Shache County (? 5% Bt cotton planting). Subsequent offspring was screened on Cry1Ac artificial diet. From 2005 to 2009, resistance gene frequency in Korla fluctuated between 0.0000 and 0.0040, while being 0.0000-0.0008 in individuals collected from Shache, and there were no significant increases in both counties from 2005 to 2009. Relative average development rates (RADRs) of larvae in F(1) tests showed significant increases from Korla, but not in Shache. RADR of F(1) larvae is significantly correlated with RADR of F(2) offspring, indicating genetic variation in response to toxin in field H. armigera population. Although the occurrence of Cry1Ac resistance alleles was low in Xinjiang cotton-planting region of China, particular attention should be given to H. armigera resistance development in Korla County.
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Genetic variation of mitochondrial DNA in Chinese populations of Pectinophora gossypiella (Lepidoptera: Gelechiidae).
Environ. Entomol.
PUBLISHED: 08-01-2010
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The pink bollworm Pectinophora gossypiella is an invasive pest insect that has successfully established populations in many cotton growing regions around the world. In this study, the genetic diversity and population structure of Chinese populations of P. gossypiella were evaluated using mitochondrial DNA sequence data (COII and Nad4). For comparison, individuals of Pakistan and America were also sequenced at the same two mtDNA regions. Extremely low genetic variation was observed in the two mitochondrial regions among all populations examined. Most of the populations harbored only one to two haplotypes. Although the Nad4 region showed relatively high haplotype diversity and nucleotide variation, ranging from 0.363 to 0.591 and from 0.00078 to 0.00140, respectively, there were only three haplotypes observed in this region. COII and Nad4 haplotype networks shaved one or two common haplotype(s) forming the center of a star-shaped phylogeny. Pairwise tests showed that most of the populations were not significantly differentiated from each other. The Chinese populations were differentiated from the Pakistani and American populations in the Nad4 region. The low level of population genetic variation of P. gossypiella is attributed to invasion bottlenecks, which may have been subsequently strengthened by its nonmigratory biology and the mosaic pattern of agricultural activities.
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Vip3Aa tolerance response of Helicoverpa armigera populations from a Cry1Ac cotton planting region.
J. Econ. Entomol.
PUBLISHED: 07-02-2010
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Transgenic cotton, Gossypium hirsutum L., that expresses the Bacillus thuringiensis (Bt) Cry1Ac toxin, holds great promise in controlling target insect pests. Evolution of resistance by target pests is the primary threat to the continued efficacy of Bt cotton. To thwart pest resistance evolution, a transgenic cotton culitvar that produces two different Bt toxins, cry1Ac and vip3A genes, was proposed as a successor of cry1Ac cotton. This article reports on levels of Vip3Aa tolerance in Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) populations from the Cry1Ac cotton planting region in China based on bioassays of the F1 generation of isofemale lines. In total, 80 isofemale families of H. armigera from Xiajin county of Shandong Province (an intensive Bt cotton planting area) and 93 families from Anci county of Hebei Province (a multiple-crop system including corn [Zea mays L.] , soybean [Glycine max (L.) Merr.], peanut (Arachis hypogaea L.), and Bt cotton) were screened with a discriminating concentration of both Cry1Ac- and Vip3A-containing diets in 2009. From data on the relative average development rates and percentage of larval weight inhibition of F1 full-sib families tested simultaneously on Cry1Ac and Vip3Aa, results indicate that responses to Cry1Ac and Vip3Aa were not genetically correlated in field population ofH. armigera. This indicates that the threat of cross-resistance between Cry1Ac and Vip3A is low in field populations of H. armigera. Thus, the introduction of Vip3Aa/Cry1Ac-producing lines could delay resistance evolution in H. armigera in Bt cotton planting area of China.
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Phytase transgenic maize does not affect the development and nutrition utilization of Ostrinia furnacalis and Helicoverpa armigera.
Environ. Entomol.
PUBLISHED: 06-17-2010
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Use of transgenic maize expressing phytase in seeds as feedstuff can greatly increase phosphate availability to livestock and poultry. Because phosphorus is an essential mineral for all living organisms, growing of phytase transgenic maize may affect the performance of the arthropod community in maize fields. We conducted a preliminary study to assess the potential effects of phytase transgenic maize (BVLA430101) on two herbivore species, Ostrinia furnacalis (Guenée) and Helicoverpa armigera (Hübner), both of which are directly exposed to high concentrations of phytase caused by ingestion of transgenic maize kernels. Our results showed that for both species, survival and duration of the first and second instars and fresh weight of the third instar were not affected when fed transgenic phytase maize kernels compared with those fed nontransformed near isoline kernels. Similarly, there was no statistical difference detected for the same life table parameters when the herbivores were fed artificial diet containing either transgenic phytase maize meal or nontransformed maize meal. In addition, the nutrition utilization of the two species was evaluated with the same diet treatments by comparing the following indices: relative food consumption rate (RCR), relative metabolic rate (RMR), efficiency of approximate digestibility (EAD), efficiency of conversation of ingested food (ECI), and efficiency of conversation of digested food (ECD). No statistical difference was detected for any index of either species between transgenic maize and nontransformed maize treatments. These results provide useful baseline information for further studies to assess the potential effects of phytase transgenic maize on other arthropods in maize fields.
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Cotton bollworm resistance to Bt transgenic cotton: a case analysis.
Sci China Life Sci
PUBLISHED: 05-13-2010
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Cotton bollworm (Helicoverpa armigera) is one of the most serious insect pests of cotton. Transgenic cotton expressing Cry toxins derived from a soil bacterium, Bacillus thuringiensis (Bt), has been produced to target this pest. Bt cotton has been widely planted around the world, and this has resulted in efficient control of bollworm populations with reduced use of synthetic insecticides. However, evolution of resistance by this pest threatens the continued success of Bt cotton. To date, no field populations of bollworm have evolved significant levels of resistance; however, several laboratory-selected Cry-resistant strains of H. armigera have been obtained, which suggests that bollworm has the capacity to evolve resistance to Bt. The development of resistance to Bt is of great concern, and there is a vast body of research in this area aimed at ensuring the continued success of Bt cotton. Here, we review studies on the evolution of Bt resistance in H. armigera, focusing on the biochemical and molecular basis of Bt resistance. We also discuss resistance management strategies, and monitoring programs implemented in China, Australia, and India.
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Mirid bug outbreaks in multiple crops correlated with wide-scale adoption of Bt cotton in China.
Science
PUBLISHED: 05-13-2010
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Long-term ecological effects of transgenic Bacillus thuringiensis (Bt) crops on nontarget pests have received limited attention, more so in diverse small holder-based cropping systems of the developing world. Field trials conducted over 10 years in northern China show that mirid bugs (Heteroptera: Miridae) have progressively increased population sizes and acquired pest status in cotton and multiple other crops, in association with a regional increase in Bt cotton adoption. More specifically, our analyses show that Bt cotton has become a source of mirid bugs and that their population increases are related to drops in insecticide use in this crop. Hence, alterations of pest management regimes in Bt cotton could be responsible for the appearance and subsequent spread of nontarget pests at an agro-landscape level.
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Electrophysiological and behavioral responses of Microplitis mediator (Hymenoptera: Braconidae) to caterpillar-induced volatiles from cotton.
Environ. Entomol.
PUBLISHED: 04-15-2010
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Microplitis mediator Haliday (Hymenoptera: Braconidae) is an important larval endoparasitoid of various lepidopteran pests, including Helicoverpa armigera (Hübner). In China, H. armigera is a key pest of cotton and is currently the focus of several biological control efforts that use M. mediator as principal natural enemy of this pest. To improve the success of biological control efforts, behavioral studies are needed that shed light on the interaction between M. mediator and H. armigera. In this study, we determined M. mediator response to volatile compounds from undamaged, mechanically injured, or H. armigera--damaged plants and identified attractive volatiles. In Y-tube olfactometer assays, we found that mechanically damaged plants and/or plants treated with H. armigera oral secretions did not attract wasps. However, volatiles from H. armigera-damaged plants elicited a strong attraction of both M. mediator sexes. Headspace extracts from H. armigera-damaged cotton were analyzed by coupled gas chromatography-electroantennographic detection (GC-EAD), and a total of seven different compounds were found to elicit electroantennogram (EAG) responses, including an unknown compound. Six different EAD-active volatiles were identified from caterpillar-damaged cotton plants, of which 3, 7-dimethyl-1, 3, 6-octatriene and (Z)-3-hexenyl acetate were the principal compounds. Olfactometer assays indicated that individual synthetic compounds of 3, 7-dimethyl-1, 3, 6-octatriene, (Z)-3-hexenyl acetate, and nonanal were attractive to M. mediator. Field cage studies showed that parasitism of H. armigera larvae by M. mediator was higher on cotton plants to which 3,7-dimethyl-1,3, 6-octatriene was applied. Our results show that the combination of terpenoids and green leaf volatiles may not only facilitate host, mate, or food location but may also increase H. armigera parasitism by M. mediator.
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Attenuation of Forkhead signaling by the retinal determination factor DACH1.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 03-29-2010
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The Drosophila Dachshund (Dac) gene, cloned as a dominant inhibitor of the hyperactive growth factor mutant ellipse, encodes a key component of the retinal determination gene network that governs cell fate. Herein, cyclic amplification and selection of targets identified a DACH1 DNA-binding sequence that resembles the FOX (Forkhead box-containing protein) binding site. Genome-wide in silico promoter analysis of DACH1 binding sites identified gene clusters populating cellular pathways associated with the cell cycle and growth factor signaling. ChIP coupled with high-throughput sequencing mapped DACH1 binding sites to corresponding gene clusters predicted in silico and identified as weight matrix resembling the cyclic amplification and selection of targets-defined sequence. DACH1 antagonized FOXM1 target gene expression, promoter occupancy in the context of local chromatin, and contact-independent growth. Attenuation of FOX function by the cell fate determination pathway has broad implications given the diverse role of FOX proteins in cellular biology and tumorigenesis.
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Characterization of a Cry1Ac toxin-binding alkaline phosphatase in the midgut from Helicoverpa armigera (Hübner) larvae.
J. Insect Physiol.
PUBLISHED: 02-05-2010
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Midgut membrane-bound alkaline phosphatases (mALP) tethered to the brush border membrane surface by a glycosylphosphatidylinositol (GPI) anchor have been proposed as crucial for Cry1Ac intoxication. In the present work, two full-length cDNAs-encoding alkaline phosphatases in the midgut of Helicoverpa armigera larvae were cloned and named HaALP1 (GenBank accession no. EU729322) and HaALP2 (GenBank accession no. EU729323), respectively. These two clones displayed high identity (above 94%) at the amino acid sequence, indicating that they may represent allelic variants, and were predicted to contain a GPI anchor. Protein sequence alignment revealed that HaALPs were grouped with mALP from the Heliothis virescens midgut. The HaALP1 and HaALP2 ( approximately 68kDa) proteins were heterologously expressed in Sf9 cells using a baculovirus expression system and purified to homogeneity. Ligand blot and dot blot analysis revealed that the Cry1Ac bound to both denatured and native purified HaALPs. Data from lectin blots, competition assays with soybean agglutinin (SBA) lectin and GalNAc binding inhibition assays were indicative of the presence of GalNAc on HaALPs and binding of Cry1Ac toxin to this residue. This observation was further confirmed through N-glycosidase digestion of HaALPs, which resulted in reduced Cry1Ac binding. Our data represent the first report on HaALPs and their putative role as receptors for Cry1Ac toxin in H. armigera.
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Antisera-mediated in vivo reduction of Cry1Ac toxicity in Helicoverpa armigera.
J. Insect Physiol.
PUBLISHED: 11-05-2009
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A functional assessment of Bacillus thuringiensis (Bt) toxin receptors in the midgut of lepidopteran insects will facilitate understanding of the toxin mode of action and provide effective strategies to counter the development of resistance. In this study, we produced anti-aminopeptidase (APN) and anti-cadherin sera with purified Cry1Ac toxin-binding APN or cadherin fragments from Heliocoverpa armigera. Antisera were evaluated for their effects on Cry1Ac toxicity through bioassays. Our results indicated that both the anti-APN and anti-cadherin sera reduced Cry1Ac toxicity in vivo, although cadherin antiserum reduced toxicity more than APN antiserum. These results suggest that both APN and cadherin are involved in Cry1Ac intoxication of H. armigera, evidence that the pore formation model may be representative of Cry1Ac toxin mode of action in this insect.
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Frequency of Bt resistance alleles in H. armigera during 2006-2008 in Northern China.
Environ. Entomol.
PUBLISHED: 08-20-2009
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Helicoverpa armigera is an important lepidopteran pest of cotton in China. From 2002, the frequency of Bt resistance alleles and quantitative shifts in larval Cry1Ac tolerance of field H. armigera population were monitored using bioassays of F(1) and F(2) offspring of isofemale lines from Xiajin County of Shandong Province (an intensive Bt cotton planting area) and Anci County of Hebei Province (a multiple-crop system including corn, soybean, peanut, and Bt cotton) in northern China. During 2006-2008, a total of 2,306 isofemale lines from the Xiajin population and a total of 1,270 isofemale lines from the Anci population were successfully screened on Cry1Ac diets. For each year, it was estimated that the major resistance gene frequency in Xiajin population in 2006, 2007, and 2008 was 0, 0.00022, and 0.00033, respectively. No major alleles conferring resistance to Cry1Ac were found in the Anci population; the frequency of resistance alleles for Cry1Ac was 0. Based on the relative average development rates (RADRs) of H. armigera larvae in F(1) tests, no substantial increase in Cry1Ac tolerance was found in either location over the 3-yr period. There were also significantly positive correlations between RADR of lines in the F(1) generation and the RADR of their F(2) offspring, indicating genetic variation in response to toxin. The low frequency of resistance alleles found in this study and in our previous results from 2002 to 2005 suggest the frequency of resistance alleles has remained low and that natural refugia resistance management strategy maybe effective for delaying resistance evolution in H. armigera to Bt cotton in northern China.
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Cry2Ab tolerance response of Helicoverpa armigera (Lepidoptera: Noctuidae) populations from CrylAc cotton planting region.
J. Econ. Entomol.
PUBLISHED: 07-21-2009
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Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is an important lepidopteran pest of cotton, Gossypium hirsutum L., in Asia. Transgenic cotton expressing the cry1Ac gene from Bacillus thuringiensis (Bt) has been widely planted for control of this pest. For managing the potential risk from resistance evolution in this pest, a new transgenic Bt cotton containing cry1Ac and cry2Ab genes (gene pyramided strategy) was designed as a successor of cry1Ac cotton. This article reports on levels of Cry2Ab tolerance in H. armigera populations from CrylAc cotton planting region in China based on bioassays of F1 and F2 offspring of isofemale lines. In total, 572 isofemale families of H. armigera from Xiajin County of Shandong Province (an intensive Bt cotton-planting area) and 124 families from Anci County of Hebei Province [a multiple-crop system, including corn (Zea mays L.), soybean (Gycine max (L.) Merr., peanut (Arachis spp.), and Bt cotton] were screened with both Cry1Ac- and Cry2Ab-containing diets in 2008. The bioassays results indicated that relative average development rates (RADR) of F1 full-sib families from field-collected female moths on Cry1Ac- and Cry2Ab-containing diet were positively correlated. The same correlation was found in the F2 generation, indicating cross-tolerance between Cry1Ac and Cry2Ab in field populations of H. armigera in Yellow River cotton-farming region of China. This cross-tolerance must be considered in evaluating the utility of pyramiding Bt genes in cotton for delaying evolution of resistance.
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The cell fate determination factor DACH1 is expressed in estrogen receptor-alpha-positive breast cancer and represses estrogen receptor-alpha signaling.
Cancer Res.
PUBLISHED: 07-17-2009
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The Dachshund (dac) gene, initially cloned as a dominant inhibitor of the Drosophila hyperactive EGFR mutant ellipse, encodes a key component of the cell fate determination pathway involved in Drosophila eye development. Analysis of more than 2,200 breast cancer samples showed improved survival by some 40 months in patients whose tumors expressed DACH1. Herein, DACH1 and estrogen receptor-alpha (ERalpha) expressions were inversely correlated in human breast cancer. DACH1 bound and inhibited ERalpha function. Nuclear DACH1 expression inhibited estradiol (E(2))-induced DNA synthesis and cellular proliferation. DACH1 bound ERalpha in immunoprecipitation-Western blotting, associated with ERalpha in chromatin immunoprecipitation, and inhibited ERalpha transcriptional activity, requiring a conserved DS domain. Proteomic analysis identified proline, glutamic acid, and leucine rich protein 1 (PELP1) as a DACH1-binding protein. The DACH1 COOH terminus was required for binding to PELP1. DACH1 inhibited induction of ERalpha signaling. E(2) recruited ERalpha and disengaged corepressors from DACH1 at an endogenous ER response element, allowing PELP1 to serve as an ERalpha coactivator. DACH1 expression, which is lost in poor prognosis human breast cancer, functions as an endogenous inhibitor of ERalpha function.
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The Dachshund gene in development and hormone-responsive tumorigenesis.
Trends Endocrinol. Metab.
PUBLISHED: 05-20-2009
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The dachshund (dac) gene was initially described as a mutant phenotype in flies featuring extremely short legs relative to their body length. Functioning as a dominant suppressor of the ellipse mutation, a hypermorphic allele of the Epidermal Growth Factor Receptor (EGFR), the dac gene plays a key role in metazoan development, regulating ocular, limb, brain, and gonadal development. In the Drosophila eye, dac is a key component of the Retinal Determination Gene Network (RDGN) governing the normal initiation of the morphogenetic furrow and thereby eye development. Recent studies have demonstrated an important role for human Dachshund homologue (DACH1) in tumorigenesis, in particular, breast, prostate and ovarian cancer. The molecular mechanisms by which DACH1 regulates differentiation and tumorigenesis are discussed herein.
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Mutation of an aminopeptidase N gene is associated with Helicoverpa armigera resistance to Bacillus thuringiensis Cry1Ac toxin.
Insect Biochem. Mol. Biol.
PUBLISHED: 04-09-2009
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A Cry1Ac-resistant strain (Bt-R) of Helicoverpa armigera, with 2971-fold resistance, was derived by selection with Cry1Ac toxin for 75 generations. We used cDNA-amplified fragment length polymorphism analysis to identify those genes differentially expressed in the Cry1Ac-resistant and -susceptible strains, which revealed 212 differentially expressed transcripts among 2000 screened cDNAs. Among these transcript-derived fragments (TDFs), 37 showed some homology to known sequences, including Aminopeptidase N (APN), which is expressed in the midgut epithelium and has been implicated as a Cry1A subfamily receptor in several moths, including H. armigera. We confirmed the TDF by RT-PCR and identified a deletion mutation of apn1 in the Bt-R strain. We expressed the TDF in bacteria. The partial HaAPN1-96S wild-type protein, bound to Cry1Ac on ligand blots, whereas HaAPN1-BtR did not. This suggested that HaAPN1 is a receptor for Bt Cry1Ac and that its deletion mutation is associated with Cry1Ac resistance in H. armigera. The absence of one binding site is responsible for its resistance to Cry1Ac. We developed an allele-specific PCR to monitor whether the apn1 gene in an H. armigera field population produced a similar mutation. No deleted mutants were found in 2250 individuals collected from the field in 2006-2007.
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The cell fate determination factor dachshund inhibits androgen receptor signaling and prostate cancer cellular growth.
Cancer Res.
PUBLISHED: 04-07-2009
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Initially isolated as the dominant suppressor of the mutant epidermal growth factor receptor (ellipse), the Dachshund gene plays a key role in metazoan development regulating the Retinal Determination Gene Network. Herein, the DACH1 gene was expressed in normal prostate epithelial cells with reduced expression in human prostate cancer. DACH1 inhibited prostate cancer cellular DNA synthesis, growth in colony forming assays, and blocked contact-independent growth in soft agar assays. DACH1 inhibited androgen receptor (AR) activity, requiring a conserved DS Domain (Dachshund domain conserved with Ski/Sno) that bound NCoR/HDAC and was recruited to an androgen-responsive gene promoter. DACH1 inhibited ligand-dependent activity of AR mutations identified in patients with androgen-insensitive prostate cancer. The DS domain was sufficient for repression of the AR wild-type but failed to repress an AR acetylation site point mutant. These studies show a role for the Retinal Determination Gene Network in regulating cellular growth and signaling in prostate cancer.
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Nuclear factor-kappaB enhances ErbB2-induced mammary tumorigenesis and neoangiogenesis in vivo.
Am. J. Pathol.
PUBLISHED: 04-06-2009
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The (HER2/Neu) ErbB2 oncogene is commonly overexpressed in human breast cancer and is sufficient for mammary tumorigenesis in transgenic mice. Nuclear factor (NF)-kappaB activity is increased in both human and murine breast tumors. The immune response to mammary tumorigenesis may regulate tumor progression. The role of endogenous mammary epithelial cell NF-kappaB had not previously been determined in immune-competent animals. Furthermore, the role of the NF-kappaB components, p50 and p65, in tumor growth was not known. Herein, the expression of a stabilized form of the NF-kappaB-inhibiting IkappaBalpha protein (IkappaBalphaSR) in breast tumor cell lines that express oncogenic ErbB2 inhibited DNA synthesis and growth in both two- and three-dimensional cultures. Either NF-kappaB inhibition or selective silencing of p50 or p65 led to a loss of contact-independent tumor growth in vitro. IkappaBalphaSR reversed the features of the oncogene-induced phenotype under three-dimensional growth conditions. The NF-kappaB blockade inhibited ErbB2-induced mammary tumor growth in both immune-competent and immune-deficient mice. These findings were associated with both reduced tumor microvascular density and a reduction in the amount of vascular endothelial growth factor. The expression of IkappaBalphaSR in breast cancer tumors inhibited angiogenesis. Thus, mammary epithelial cell NF-kappaB activity enhances ErbB2-mediated mammary tumorigenesis in vivo by promoting both growth and survival signaling via the promotion of tumor vasculogenesis.
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Reduction of Bacillus thuringiensis Cry1Ac toxicity against Helicoverpa armigera by a soluble toxin-binding cadherin fragment.
J. Insect Physiol.
PUBLISHED: 03-20-2009
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A cadherin-like protein has been identified as a putative receptor for Bacillus thuringiensis (Bt) Cry1Ac toxin in Helicoverpa armigera and plays a key role in Bt insecticidal action. In this study, we produced a fragment from this H. armigera Cry1Ac toxin-binding cadherin that included the predicted toxin-binding region. Binding of Cry1Ac toxin to this cadherin fragment facilitated the formation of a 250-kDa toxin oligomer. The cadherin fragment was evaluated for its effect on Cry1Ac toxin-binding and toxicity by ligand blotting, binding assays, and bioassays. The results of ligand blotting and binding assays revealed that the binding of Cry1Ac to H. armigera midgut epithelial cells was reduced under denaturing or native conditions in vitro. Bioassay results indicated that toxicities from Cry1Ac protoxin or activated toxin were reduced in vivo by the H. armigera cadherin fragment. The addition of the cadherin fragment had no effect on Cry2Ab toxicity.
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Trade-offs between flight and fecundity in the soybean aphid (Hemiptera: Aphididae).
J. Econ. Entomol.
PUBLISHED: 03-04-2009
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The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is native to eastern Asia and was accidentally introduced into North America in 2000. Within a few years, it was found throughout the U.S. and Canadian soybean-growing regions. The spread of A. glycines in North America is partly ascribed to its great flight capacity. We conducted direct measurements of flight performance of winged A. glycines adults and correlated this to their subsequent longevity and fecundity to determine whether there are trade-offs between flight and fecundity. We also estimated fecundity and development time of the offspring of females that had flown varying distances to examine potential maternal effects linked to flight. The experiment was conducted using a specifically designed aphid flight mill system in which winged aphids were tethered by their abdomens and flight duration, distance and speed were quantified. Fecundity, longevity and reproductive periods of 12-h-old A. glycines alates that had engaged in > 0.5 km long flights were significantly lower than those of < 0.5-km individuals. The offspring of alates with flight experiences of > 1.5 km also had lower fecundity than those produced by individuals that had engaged in flights < 1.5 km. Our results are therefore consistent both with direct trade-offs between flight and fecundity and a trade-off between flight and fecundity via maternal effects.
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Seasonal migration of Helicoverpa armigera (Lepidoptera: Noctuidae) over the Bohai Sea.
J. Econ. Entomol.
PUBLISHED: 03-04-2009
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The seasonal migration of the Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) over the Bohai Sea was observed with a searchlight trap and an entomological radar located on a small island in the center of the sea, and through a network of light-traps around the Bohai region. The H. armigera moths were observed to migrate over the sea at least as early as May and light trapping through a network suggested migration might start as early as April, as soon as the moths had emerged from overwintering pupae. H. armigera moths migrated toward the north in southerly winds during spring and summer, and returned south on nights with northerly winds, or at altitudes where the wind was northerly, during fall. The passage of a weather front (cold or warm) or trough at approximately 1700 hours provokes migration of H. armigera over the sea. The H. armigera generally flew at altitudes of below 1,500 m above sea level (asl) with layer concentrations at 200-500 m asl, where the wind direction, wind speed, and temperature were optimum. During fall migration, H. armigera tended to orient toward the southwest and was able to compensate for the wind drift by turning clockwise when the downwind direction was < 225 degrees but counterclockwise when it was > 225 degrees. The displacement speed measured with the radar was 24-41 km/h, the duration of flight was 8-11 h and the maximum migration rate was 1,894 moths per km per h.
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Double homozygous missense mutations in DACH1 and BMP4 in a patient with bilateral cystic renal dysplasia.
Nephrol. Dial. Transplant.
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Renal hypodysplasia (RHD) is characterized by small and/or disorganized kidneys following abnormal organogenesis. Mutations in several genes have been identified recently to be associated with RHD in humans, including BMP4, a member of the transforming growth factor (TGF)-? family of growth factors. DACH1 has been proposed as a candidate gene for RHD because of its involvement in the EYA-SIX-DACH network of renal developmental genes. Here, we present a patient with renal dysplasia carrying homozygous missense mutations in both BMP4 (p.N150K) and DACH1 (p.R684C). The genotype-phenotype correlation in the family hints at an oligogenic mode of inheritance of the disease in this kindred. Functional analyses of the identified DACH1 mutation in HEK293T cells demonstrated enhanced suppression of the TGF-? pathway suggesting that both mutations could act synergistically in the development of the phenotype in this patient. This finding provides a model for RHD as an oligo-/polygenic disorder and supports a role for DACH1 in the development of RHD in humans.
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Early season host plants of Apolygus lucorum (Heteroptera: Miridae) in northern China.
J. Econ. Entomol.
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Apolygus lucorum (Meyer-Dür) (Heteroptera: Miridae) has become a severe pest of cotton and many other crops in northern China as a result of the widespread adoption of Bacillus thuringiensis (Berliner) cotton, with a corresponding reduction of broad-spectrum insecticide application in cotton fields. From the middle of April to middle June, A. lucorum feeds and develops on other host plants before dispersing to cotton fields. Effective suppression of A. lucorum populations before they enter cotton fields may be an excellent strategy for reducing the occurrence and damage of their subsequent generations in cotton fields. For that, basic information about the host plant range of A. lucorum during the early season is needed. Between 2006 and 2010, a total of 94 plant species from 41 families covering 39,956 square meters of land in natural conditions were sampled using the standard white pan beat method. Sixty-six plant species, including 45 weeds, 10 fruit trees, 5 timber trees, 4 pasture crops, and 2 arable crops were found to be hosts of A. lucorum. Among these species, Descurainia sophia (L.) Webb ex Prantl, Humulus scandens (Loureiro) Merrill, Zizyphus jujuba Miller, Vitis vinifera L., Viciafaba L., and Medicago sativa L. were identified as dominant host species because of their wide distribution and high population densities of A. lucorum. The results of this study provide useful information about the early season host range of A. lucorum, which can be used to develop effective strategies to control the pest before its dispersal to cotton fields.
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Complete genome sequence of a monosense densovirus infecting the cotton bollworm, Helicoverpa armigera.
J. Virol.
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Densoviruses (DNVs) infecting arthropods are members of the family Parvoviridae. Here we report the complete genome sequence of a novel DNV with a monosense genome that infects cotton bollworms (Helicoverpa armigera), named HaDNV-1. Alignment and phylogenetic analysis revealed that HaDNV-1 showed high identity with the genus Iteravirus.
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The halo effect: suppression of pink bollworm on non-Bt cotton by Bt cotton in China.
PLoS ONE
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In some previously reported cases, transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt) have suppressed insect pests not only in fields planted with such crops, but also regionally on host plants that do not produce Bt toxins. Here we used 16 years of field data to determine if Bt cotton caused this "halo effect" against pink bollworm (Pectinophora gossypiella) in six provinces of the Yangtze River Valley of China. In this region, the percentage of cotton hectares planted with Bt cotton increased from 9% in 2000 to 94% in 2009 and 2010. We found that Bt cotton significantly decreased the population density of pink bollworm on non-Bt cotton, with net decreases of 91% for eggs and 95% for larvae on non-Bt cotton after 11 years of Bt cotton use. Insecticide sprays targeting pink bollworm and cotton bollworm (Helicoverpa armigera) decreased by 69%. Previously reported evidence of the early stages of evolution of pink bollworm resistance to Bt cotton in China has raised concerns that if unchecked, such resistance could eventually diminish or eliminate the benefits of Bt cotton. The results reported here suggest that it might be possible to find a percentage of Bt cotton lower than the current level that causes sufficient regional pest suppression and reduces the risk of resistance.
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Widespread adoption of Bt cotton and insecticide decrease promotes biocontrol services.
Nature
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Over the past 16 years, vast plantings of transgenic crops producing insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) have helped to control several major insect pests and reduce the need for insecticide sprays. Because broad-spectrum insecticides kill arthropod natural enemies that provide biological control of pests, the decrease in use of insecticide sprays associated with Bt crops could enhance biocontrol services. However, this hypothesis has not been tested in terms of long-term landscape-level impacts. On the basis of data from 1990 to 2010 at 36 sites in six provinces of northern China, we show here a marked increase in abundance of three types of generalist arthropod predators (ladybirds, lacewings and spiders) and a decreased abundance of aphid pests associated with widespread adoption of Bt cotton and reduced insecticide sprays in this crop. We also found evidence that the predators might provide additional biocontrol services spilling over from Bt cotton fields onto neighbouring crops (maize, peanut and soybean). Our work extends results from general studies evaluating ecological effects of Bt crops by demonstrating that such crops can promote biocontrol services in agricultural landscapes.
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Diverse genetic basis of field-evolved resistance to Bt cotton in cotton bollworm from China.
Proc. Natl. Acad. Sci. U.S.A.
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Evolution of pest resistance reduces the efficacy of insecticidal proteins from Bacillus thuringiensis (Bt) used in sprays or in transgenic crops. Although several pests have evolved resistance to Bt crops in the field, information about the genetic basis of field-evolved resistance to Bt crops has been limited. In particular, laboratory-selected resistance to Bt toxin Cry1Ac based on recessive mutations in a gene encoding a toxin-binding cadherin protein has been identified in three major cotton pests, but previous work has not determined if such mutations are associated with field-selected resistance to Bt cotton. Here we show that the most common resistance alleles in field populations of cotton bollworm, Helicoverpa armigera, selected with Bt cotton in northern China, had recessive cadherin mutations, including the deletion mutation identified via laboratory selection. However, unlike all previously studied cadherin resistance alleles, one field-selected cadherin resistance allele conferred nonrecessive resistance. We also detected nonrecessive resistance that was not genetically linked with the cadherin locus. In field-selected populations, recessive cadherin alleles accounted for 75-84% of resistance alleles detected. However, most resistance alleles occurred in heterozygotes and 59-94% of resistant individuals carried at least one nonrecessive resistance allele. The results suggest that resistance management strategies must account for diverse resistance alleles in field-selected populations, including nonrecessive alleles.
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