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Find video protocols related to scientific articles indexed in Pubmed.
Efficient replication of Epstein-Barr virus in stratified epithelium in vitro.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 10-13-2014
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Epstein-Barr virus is a ubiquitous human herpesvirus associated with epithelial and lymphoid tumors. EBV is transmitted between human hosts in saliva and must cross the oral mucosal epithelium before infecting B lymphocytes, where it establishes a life-long infection. The latter process is well understood because it can be studied in vitro, but our knowledge of infection of epithelial cells has been limited by the inability to infect epithelial cells readily in vitro or to generate cell lines from EBV-infected epithelial tumors. Because epithelium exists as a stratified tissue in vivo, organotypic cultures may serve as a better model of EBV in epithelium than monolayer cultures. Here, we demonstrate that EBV is able to infect organotypic cultures of epithelial cells to establish a predominantly productive infection in the suprabasal layers of stratified epithelium, similar to that seen with Kaposi's-associated herpesvirus. These cells did express latency-associated proteins in addition to productive-cycle proteins, but a population of cells that exclusively expressed latency-associated viral proteins could not be detected; however, an inability to infect the basal layer would be unlike other herpesviruses examined in organotypic cultures. Furthermore, infection did not induce cellular proliferation, as it does in B cells, but instead resulted in cytopathic effects more commonly associated with productive viral replication. These data suggest that infection of epithelial cells is an integral part of viral spread, which typically does not result in the immortalization or enhanced growth of infected epithelial cells but rather in efficient production of virus.
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Partnerships for development: Municipal solid waste management in Kasese, Uganda.
Waste Manag Res
PUBLISHED: 06-20-2014
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Municipal solid waste management systems of many developing countries are commonly constrained by factors such as limited financial resources and poor governance, making it a difficult proposition to break with complex, entrenched and unsustainable technologies and systems. This article highlights strategic partnerships as a way to affect a distributed agency among several sets of stakeholders to break so-called path dependencies, which occur when such unsustainable pathways arise, stabilize and become self-reinforcing over time. Experiences from a North-South collaborative effort provide some lessons in such partnership building: In Uganda and Denmark, respectively, the World Wildlife Fund and the network organization access2innovation have mobilized stakeholders around improving the municipal solid waste management system in Kasese District. Through a municipal solid waste management system characterization and mapping exercise, some emergent lessons and guiding principles in partnership building point to both pitfalls and opportunities for designing sustainable pathways. First, socio-technical lock-in effects in the municipal solid waste management system can stand in the way of partnerships based on introducing biogas or incineration technologies. However, opportunities in the municipal solid waste management system can exist within other areas, and synergies can be sought with interlinking systems, such as those represented with sanitation.
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Design principles for efficient, repeated jumpgliding.
Bioinspir Biomim
PUBLISHED: 05-22-2014
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Combined jumping and gliding locomotion, or 'jumpgliding', can be an efficient way for small robots or animals to travel over cluttered terrain. This paper presents functional requirements and models for a simple jumpglider which formalize the benefits and limitations of using aerodynamic surfaces to augment jumping ability. Analysis of the model gives insight into design choices and control strategies for higher performance and to accommodate special conditions such as a slippery launching surface. The model informs the design of a robotic platform that can perform repeated jumps using a carbon fiber spring and a pivoting wing. Experiments with two different versions of the platform agree with predictions from the model and demonstrate a significantly greater range, and lower cost-of-transport, than a comparable ballistic jumper.
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Effect of oxygen tension on the amino Acid utilisation of human embryonic stem cells.
Cell. Physiol. Biochem.
PUBLISHED: 01-29-2014
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Background/Aims: Human embryonic stem cells (hESCs) are a potential source of cells for treatment of many degenerative diseases, but in culture have a propensity to spontaneously differentiate, possibly due to suboptimal conditions. Culture at low oxygen tensions improves hESC maintenance and regulates carbohydrate metabolism. Hence, a greater understanding of the nutrient requirements of hESCs will allow production of more appropriate culture media. This study aims to investigate the effect of environmental oxygen tension on the amino acid metabolism of hESCs. Methods: The production or depletion of amino acids by hESCs cultured at 5% or 20% oxygen in the presence or absence of FGF2 was measured by reversephase HPLC. Results: Atmospheric oxygen, or removal of FGF2 from hESCs cultured at 5% oxygen, perturbed the uptake or release of individual amino acids and the total amino acid turnover compared to hESCs cultured at 5% oxygen. In particular, serine uptake was reduced at 20% oxygen and by removal of FGF2. Conclusions: Highly pluripotent hESCs, cultured at 5% oxygen, demonstrate a greater amino acid turnover than hESCs cultured at 20% oxygen, or without FGF2. These data suggest that amino acid turnover could be used as a measure of the self-renewal capacity of hESCs. © 2014 S. Karger AG, Basel.
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HIF-2? Regulates NANOG Expression in Human Embryonic Stem Cells following Hypoxia and Reoxygenation through the Interaction with an Oct-Sox Cis Regulatory Element.
PLoS ONE
PUBLISHED: 01-01-2014
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Low O2 tension is beneficial for human embryonic stem cell (hESC) maintenance but the mechanism of regulation is unknown. HIF-2? was found to bind directly to predicted hypoxic response elements (HREs) in the proximal promoter of OCT4, NANOG and SOX2 only in hESCs cultured under hypoxia (5% O2). This binding induced an array of histone modifications associated with gene transcription while a heterochromatic state existed at atmospheric O2. Interestingly, an enhanced euchromatic state was found when hESCs were exposed to hypoxia followed by 72 hours reoxygenation. This was sustained by HIF-2? which enhanced stemness by binding to an oct-sox cis-regulatory element in the NANOG promoter. Thus, these data have uncovered a novel role of HIF-2? as a direct regulator of key transcription factors controlling self-renewal in hESCs but also in the induction of epigenetic modifications ensuring a euchromatic conformation which enhances the regenerative potential of these cells.
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Characterizations of Structural, Biochemical, and Nutritive Profiles in Silage among Cool-Season Corn Cultivars in Relation to Heat Units (aCHU, dCHU) with Curvilinear Response and Multivariate Analyses.
J. Agric. Food Chem.
PUBLISHED: 12-05-2013
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Molecular spectroscopy is able to reveal structural features of biomaterials. Corn grown in Canadian prairies is known as cool-season corn, which is different from warm-season corn varieties. To our knowledge, to date, there has been no study on the magnitude difference in structure on a molecular basis among cultivars, no study on biochemical and nutritive profiles associated with heat unit, and no study on how heat unit affects the molecular structure and biochemical and nutritive profiles. This study investigates how corn varieties grown in cooler climates are affected by crop heat units (CHU) in relation to molecular spectral profiles, nutrient storage, biochemical composition, and nutritive value of silage among different cool-season corn cultivars. Corn cultivars (Pioneer and Dekalb) were from seven farm locations, and samples were analyzed for major nutrients (digestible and metabolic energy and protein). The Fourier transform infrared (FT/IR) spectroscopic technique was applied to understand and differentiate molecular structural spectral profiles in silage. A correlation (P < 0.05) of CHU with some nutrients (mean ± SD, %DM) (CP, 8.1 ± 1.3, r = 0.56; NDF, 56.3 ± 3.5, r = -0.54; ADF, 33.6 ± 2.3, r = -0.71; NDICP, 1.6 ± 0.4, r = -0.66; SCP, 4.2 ± 1.3, r = 0.61), protein and carbohydrate fractions (mean ± SD, %DM) (PB1 (= fast degradable protein fraction), 1.3 ± 0.4, r = 0.54; PB3 (= slowly degradable protein fraction), 1.5 ± 0.4, r = -0.74; CB2 (= medium degradable carbohydrate fraction), 45.1 ± 2.8, r = -0.65; CB3 (= slowly degradable carbohydrate fraction), 13.9 ± 0.9, r = -0.54) and intestinal availability of ruminally degraded fractions (mean ± SD, %DM) (rdPB1, 1.1 ± 0.3, r = 0.54; rdPB3, 1.0 ± 0.3, r = -0.74; RDP, 6.6 ± 1.2, r = 0.59; rdCB2, 40.0 ± 2.5, r = -0.65; rdCB3, 8.9 ± 0.6, r = 0.54; RDCHO, 50.1 ± 2.9, r = -0.65) was found contentious. Molecular spectral data indicated many similarities and few differences among the cultivars. However, CHU correlated (r = -0.4, P < 0.05) with molecular spectral intensity ratio of carbohydrate to amide I. This result indicates that molecular structural differences may be influenced by epiphytic bacterial compounds. Cool corn cultivars were grown acceptably well in cooler dry climates, and those silages had acceptable nutrient levels for cattle. Cultivars that reached target CHU were found to be optimal in nutrient and energy synchronization aspect.
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Investigating the Molecular Structural Features of Hulless Barley (Hordeum vulgare L.) in Relation to Metabolic Characteristics Using Synchrotron-Based Fourier Transform Infrared Microspectroscopy.
J. Agric. Food Chem.
PUBLISHED: 11-18-2013
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The synchrotron-based Fourier transform infrared microspectroscopy (SR-FTIRM) technique was used to quantify molecular structural features of the four hulless barley lines with altered carbohydrate traits [amylose, 1-40% of dry matter (DM); ?-glucan, 5-10% of DM] in relation to rumen degradation kinetics, intestinal nutrient digestion, and predicted protein supply. Spectral features of ?-glucan (both area and heights) in hulless barley lines showed a negative correlation with protein availability in the small intestine, including truly digested protein in the small intestine (DVE) (r = -0.76, P < 0.01; r = -0.84, P < 0.01) and total metabolizable protein (MP) (r = -0.71, P < 0.05; r = -0.84, P < 0.01). Variation in absorption intensities of total carbohydrate (CHO) was observed with negative effects on protein degradation, digestion, and potential protein supply (P < 0.05). Molecular structural features of CHO in hulless barley have negative effects on the supply of true protein to ruminants. The results clearly indicated the impact of the carbohydrate-protein structure and matrix.
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Molecular structure, chemical and nutrient profiles, and metabolic characteristics of the proteins and energy in new cool-season corn varieties harvested as fresh forage for dairy cattle.
J. Dairy Sci.
PUBLISHED: 03-21-2013
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To our knowledge, no previous research exists concerning the molecular structure and metabolic characteristics of the proteins and energy that new cool-season corn varieties provide for dairy cattle. The objectives of this study were to identify the differences in the molecular structures of proteins among several new cool-season corn varieties [Pioneer P7443R, Pioneer P7213R, Pioneer P7535R (Pioneer Hi-Bred International Inc., Johnston, IA), Hyland Baxxos RR, Hyland SR22, and Hyland SR06 (Hyland Seeds, Blenheim, ON, Canada)] using Fourier transform infrared attenuated total reflectance (FT/IR-ATR) molecular spectroscopy, and to determine the nutrient profile and supply that each variety provided for dairy cattle. The protein molecular structure studies showed that the amide I to amide II ratio ranged from 1.09 to 1.66 and that the ?-helix to ?-sheet ratio ranged from 0.95 to 1.01 among the new cool-season corn varieties. Energy content was significantly different among the new varieties. We found significant differences in the protein and carbohydrate subfractions and in the ruminal degradation kinetics of the organic matter, crude protein, starch, and neutral detergent fiber of the new varieties. The new varieties had similar estimated intestinal digestibilities for rumen undegraded crude protein. However, the new varieties had significant differences in predicted total truly absorbable protein, ranging from 39 to 57 g/kg of dry matter, indicating that these newly developed varieties are satisfactory sources of truly absorbed protein for dairy cattle. Further study on the molecular structure profiles of cool-season corn in relation to its nutrient utilization and availability in dairy cattle is necessary.
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Positioning ganglioside D3 as an immunotherapeutic target in lymphangioleiomyomatosis.
Am. J. Pathol.
PUBLISHED: 02-19-2013
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Tumors that develop in lymphangioleiomyomatosis (LAM) as a consequence of biallelic loss of TSC1 or TSC2 gene function express melanoma differentiation antigens. However, the percentage of LAM cells expressing these melanosomal antigens is limited. Here, we report the overexpression of ganglioside D3 (GD3) in LAM. GD3 is a tumor-associated antigen otherwise found in melanoma and neuroendocrine tumors; normal expression is largely restricted to neuronal cells in the brain. We also observed markedly reduced serum antibody titers to GD3, which may allow for a population of GD3-expressing LAM cells to expand within patients. This is supported by the demonstrated sensitivity of cultured LAM cells to complement mediated cytotoxicity via GD3 antibodies. GD3 can serve as a natural killer T (NKT) cell antigen when presented on CD1d molecules expressed on professional antigen-presenting cells. Although CD1d-expressing monocyte derivatives were present in situ, enhanced NKT-cell recruitment to LAM lung was not observed. Cultured LAM cells retained surface expression of GD3 over several passages and also expressed CD1d, implying that infiltrating NKT cells can be directly cytotoxic toward LAM lung lesions. Immunization with antibodies to GD3 may thus be therapeutic in LAM, and enhancement of existing NKT-cell infiltration may be effective to further improve antitumor responses. Overall, we hereby establish GD3 as a suitable target for immunotherapy of LAM.
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Environmental oxygen tension regulates the energy metabolism and self-renewal of human embryonic stem cells.
PLoS ONE
PUBLISHED: 01-01-2013
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Energy metabolism is intrinsic to cell viability but surprisingly has been little studied in human embryonic stem cells (hESCs). The current study aims to investigate the effect of environmental O2 tension on carbohydrate utilisation of hESCs. Highly pluripotent hESCs cultured at 5% O2 consumed significantly more glucose, less pyruvate and produced more lactate compared to those maintained at 20% O2. Moreover, hESCs cultured at atmospheric O2 levels expressed significantly less OCT4, SOX2 and NANOG than those maintained at 5% O2. To determine whether this difference in metabolism was a reflection of the pluripotent state, hESCs were cultured at 5% O2 in the absence of FGF2 for 16 hours leading to a significant reduction in the expression of SOX2. In addition, these cells consumed less glucose and produced significantly less lactate compared to those cultured in the presence of FGF2. hESCs maintained at 5% O2 were found to consume significantly less O2 than those cultured in the absence of FGF2, or at 20% O2. GLUT1 expression correlated with glucose consumption and using siRNA and chromatin immunoprecipitation was found to be directly regulated by hypoxia inducible factor (HIF)-2? at 5% O2. In conclusion, highly pluripotent cells associated with hypoxic culture consume low levels of O2, high levels of glucose and produce large amounts of lactate, while at atmospheric conditions glucose consumption and lactate production are reduced and there is an increase in oxidative metabolism. These data suggest that environmental O2 regulates energy metabolism and is intrinsic to the self-renewal of hESCs.
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Pathogen and host factors are needed to provoke a systemic host response to gastrointestinal infection of Drosophila larvae by Candida albicans.
Dis Model Mech
PUBLISHED: 05-02-2011
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Candida albicans systemic dissemination in immunocompromised patients is thought to develop from initial gastrointestinal (GI) colonisation. It is unclear what components of the innate immune system are necessary for preventing C. albicans dissemination from the GI tract, but studies in mice have indicated that both neutropenia and GI mucosal damage are crucial for allowing widespread invasive C. albicans disease. Mouse models, however, provide limited applicability to genome-wide screens for pathogen or host factors - factors that might influence systemic dissemination following GI colonisation. For this reason we developed a Drosophila model to study intestinal infection by Candida. We found that commensal flora aided host survival following GI infection. Candida provoked extensive JNK-mediated death of gut cells and induced antimicrobial peptide expression in the fat body. From the side of the host, nitric oxide and blood cells influenced systemic antimicrobial responses. The secretion of SAP4 and SAP6 (secreted aspartyl proteases) from Candida was also essential for activating systemic Toll-dependent immunity.
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Cross-neutralization potential of native human papillomavirus N-terminal L2 epitopes.
PLoS ONE
PUBLISHED: 02-08-2011
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Human papillomavirus (HPV) capsids are composed of 72 pentamers of the major capsid protein L1, and an unknown number of L2 minor capsid proteins. An N-terminal "external loop" of L2 contains cross-neutralizing epitopes, and native HPV16 virions extracted from 20-day-old organotypic tissues are neutralized by anti-HPV16 L2 antibodies but virus from 10-day-old cultures are not, suggesting that L2 epitopes are more exposed in mature, 20-day virions. This current study was undertaken to determine whether cross-neutralization of other HPV types is similarly dependent on time of harvest and to screen for the most effective cross-neutralizing epitope in native virions.
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Effects of partially replacing barley or corn with raw and micronised CDC SO-I oats on productive performance of lactating dairy cows.
Arch Anim Nutr
PUBLISHED: 12-01-2010
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Recently, a new genotype of oat (cv. CDC SO-I, containing low-hull lignin and high-fat groat), has been developed. The objective of this study was to determine the effects of partially replacing barley and corn with the new oat and its micronisation on lactating performance of dairy cows. In a double 4 x 4 Latin square design, eight lactating dairy cows (732 +/- 46 kg body weight [BW]; parity 4 +/- 2) received total mixed rations with a forage-to-concentrate ratio of 50:50 (DM basis). The four treatments were: T1, barley only (control); T2, raw oat, replacing 42% barley of T1; T3, micronised oat, replacing 42% barley of T1; and T4, raw oat and corn blend, replacing 100% barley of T1. The results showed that dairy cows fed the new oats (T2, T3) produced more fat (p < 0.05) and more fat corrected milk (p < 0.10) than cows fed barley only (T1). The performance of cows fed the new oat and corn blend (T4) was not significantly different from other treatments. The micronisation significantly reduced protein degradability (74 vs. 63%,p < 0.05), but increased starch degradability (87 vs. 93%,p < 0.05) of the new oat. However, the overall results suggested that micronisation did not show a significant impact on milk production. The newly developed CDC SO-I oat can replace 42% barley (in T1) as a concentrate supplement in dairy total mixed rations with an increased yield of milk fat and fat corrected milk.
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Fourier transform infrared microspectroscopic analysis of the effects of cereal type and variety within a type of grain on structural makeup in relation to rumen degradation kinetics.
J. Agric. Food Chem.
PUBLISHED: 07-11-2009
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The objectives of this study were to use Fourier transform infrared microspectroscopy (FTIRM) to determine structural makeup (features) of cereal grain endosperm tissue and to reveal and identify differences in protein and carbohydrate structural makeup between different cereal types (corn vs barley) and between different varieties within a grain (barley CDC Bold, CDC Dolly, Harrington, and Valier). Another objective was to investigate how these structural features relate to rumen degradation kinetics. The items assessed included (1) structural differences in protein amide I to nonstructural carbohydrate (NSC, starch) intensity and ratio within cellular dimensions; (2) molecular structural differences in the secondary structure profile of protein, alpha-helix, beta-sheet, and their ratio; (3) structural differences in NSC to amide I ratio profile. From the results, it was observed that (1) comparison between grain types [corn (cv. Pioneer 39P78) vs barley (cv. Harrington)] showed significant differences in structural makeup in terms of NSC, amide I to NSC ratio, and rumen degradation kinetics (degradation ratio, effective degradability of dry matter, protein and NSC) (P < 0.05); (2) comparison between varieties within a grain (barley varieties) also showed significant differences in structural makeup in terms of amide I, NSC, amide I to NSC ratio, alpha-helix and beta-sheet protein structures, and rumen degradation kinetics (effective degradability of dry matter, protein, and NSC) (P < 0.05); (3) correlation analysis showed that the amide I to NSC ratio was strongly correlated with rumen degradation kinetics in terms of the degradation rate (R = 0.91, P = 0.086) and effective degradability of dry matter (R = 0.93, P = 0.071). The results suggest that with the FTIRM technique, the structural makeup differences between cereal types and between different varieties within a type of grain could be revealed. These structural makeup differences were related to the rate and extent of rumen degradation.
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Physicochemical characteristics, hydroxycinnamic acids (ferulic acid, P-coumaric acid) and their ratio, and in situ biodegradability: comparison of genotypic differences among six barley varieties.
J. Agric. Food Chem.
PUBLISHED: 05-13-2009
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Barley contains hydroxycinnamic acids, mainly ferulic acid (FA; 3-methoxy-4-hydroxycinnamic acid) and p-coumaric acid (PCA; 4-hydroxycinnamic acid). Ferulic acid is produced via the phenylpropanoid biosynthetic pathway and covalently cross-linked to polysaccharides by ester bonds and to components of lignin mainly by ether bonds. Various studies have consistently indicated that FA is among the factors most inhibitory to the biodegradability of cell wall polysaccharides. p-Coumaric acid is also covalently linked to polysaccharides (minor) and lignin (major), but does not form the inhibitory cross-linkages as FA does and is considered to represent cell wall lignification. The objectives in this study were to (1) determine genotypic differences in physicochemical characteristics in terms of (a) two major low molecular weight hydroxycinnamic acid profiles (FA, PCA, PCA-to-FA ratio, which are associated with digestion and lignification), (b) particle size distributions (mean, median), (c) hull content, and (d) digestion-resistant fiber fractions and (2) determine genotypic differences in in situ solubilization kinetics of FA and PCA. The barley varieties grown during three consecutive years (2003, 2004, and 2005) included AC Metcalfe, CDC Dolly, McLeod, CDC Helgason, CDC Trey, and CDC Cowboy. These barleys were grown at the Kernen Crop Research Farm (KCRF, University of Saskatchewan) and managed using standard agronomic production practices. Results showed that there were significant differences in hull content (P < 0.05) among the barley varieties, with Mcleod having the highest (11% DM) and CDC Dolly and CDC Helgason the lowest hull content (9% DM). Ferulic acid ranged from 555 to 663 microg/g of DM (P < 0.05). p-Coumaric acid ranged (P < 0.05) from 283 to 345 microg/g of DM. PCA-to-FA ratios ranged (P < 0.05) from 0.49 to 0.56. Mean particle size ranged (P < 0.05) from 3.06 to 3.66 mm, and median particle size ranged (P < 0.05) from 2.71 to 3.04 mm. In situ DM degradability ranged from 44 to 49%. In situ solubilized FA fractions ranged (P < 0.05) from 60 to 72% and of PCA ranged (P < 0.05) from 71 to 81%. In conclusion, CDC Dolly was best and McLeod barley was poorest as feed barley in terms of hull and FA contents. There were significant genotypic differences in FA, PCA and their ratio, hull content, particle size distribution, and in situ solubilization of FA and PCA among the barley varieties.
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Metabolic characteristics of proteins and biomolecular spectroscopic profiles in different batches of feedstock (wheat) and their co-products (wheat distillers dried grains with solubles) from the same bioethanol processing plant.
J. Dairy Sci.
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The objectives of this study were (1) to reveal the metabolic characteristics of proteins in different batches of feedstock (wheat) for bioethanol production and their co-products (wheat distillers dried grains with solubles, wDDGS) from the same bioethanol processing plant, and (2) to characterize biomolecular spectral profile associated with nutrient digestion in the rumen and intestine of dairy cattle. The metabolic characteristics of proteins were determined using the DVE/OEB system (where DVE=total truly absorbed protein supply, and OEB=degraded balance of protein) based on chemical profiles and rumen and intestinal digestion data from dairy cattle. The biomolecular spectral characteristics were investigated by using the molecular spectroscopy technique attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FT/IR). Multivariate molecular spectral analyses-agglomerative hierarchical cluster analysis (AHCA), and principal component analysis (PCA)-were conducted to identify the spectral differences in biomolecular inherent structure among the wheat and wDDGS batches. The results showed that (1) the metabolic characteristics of proteins in the wheat and wDDGS from the same bioethanol processing plant were significantly affected by batch, with total truly absorbed protein supply (DVE value) ranging from 101 to 116 g/kg of dry matter (DM) in wheat and from 153 to 182 g/kg of DM in wDDGS; (2) the degraded balance of protein (OEB value) in the wDDGS (but not the wheat) from the same bioethanol processing plant was significantly affected by batch, with the OEB value ranging from -19 to -26 g/kg of DM in the wheat and from 145 to 181 g/kg of DM in the wDDGS; and (3) the biomolecular spectral analyses with AHCA and PCA revealed biomolecular spectral profiles and differences among the wheat and wDDGS samples.
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Molecular basis of bacterial protein Hen1 activating the ligase activity of bacterial protein Pnkp for RNA repair.
Proc. Natl. Acad. Sci. U.S.A.
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Ribotoxins cleave essential RNAs for cell killing in vivo, and the bacterial polynucleotide kinase-phosphatase (Pnkp)/hua enhancer 1 (Hen1) complex has been shown to repair ribotoxin-cleaved RNAs in vitro. Bacterial Pnkp/Hen1 is distinguished from other RNA repair systems by performing 3-terminal 2-O-methylation during RNA repair, which prevents the repaired RNA from repeated cleavage at the same site. To ensure the opportunity of 2-O-methylation by bacterial Hen1 during RNA repair and, therefore, maintain the quality of the repaired RNA, Pnkp/Hen1 has evolved to require the participation of Hen1 in RNA ligation, because Pnkp alone is unable to carry out the reaction despite possessing all signature motifs of an RNA ligase. However, the precise role of Hen1 in RNA ligation is unknown. Here, we present the crystal structure of an active RNA ligase consisting of the C-terminal half of Pnkp (Pnkp-C) and the N-terminal half of Hen1 (Hen1-N) from Clostridium thermocellum. The structure reveals that the N-terminal domain of Clostridium thermocellum (Cth) Hen1, shaped like a left hand, grabs the flexible insertion module of CthPnkp and locks its conformation via further interaction with the C-terminal addition module of CthPnkp. Formation of the CthPnkp-C/Hen1-N heterodimer creates a ligation pocket with a width for two strands of RNA, depth for two nucleotides, and the adenosine monophosphate (AMP)-binding pocket at the bottom. The structure, combined with functional analyses, provides insight into the mechanism of how Hen1 activates the RNA ligase activity of Pnkp for RNA repair.
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Fermentation, degradation and microbial nitrogen partitioning for three forage colour phenotypes within anthocyanidin-accumulating Lc-alfalfa progeny.
J. Sci. Food Agric.
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Alfalfa has the disadvantage of having a rapid initial rate of protein degradation, which results in pasture bloat, low efficiency of protein utilisation and excessive nitrogen (N) pollution into the environment for cattle. Introducing a gene that stimulates the accumulation of monomeric/polymeric anthocyanidins might reduce the ruminal protein degradation rate (by fixing protein and/or direct interaction with microbes) and additionally reduce methane emission. The objectives of this study were to evaluate in vitro fermentation, degradation and microbial N partitioning of three forage colour phenotypes (green, light purple-green (LPG) and purple-green (PG)) within newly developed Lc-progeny and to compare them with those of parental green non-transgenic (NT) alfalfa.
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What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.