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Find video protocols related to scientific articles indexed in Pubmed.
Photoperiod modulation of aggressive behavior is independent of androgens in a tropical cichlid fish.
Gen. Comp. Endocrinol.
PUBLISHED: 07-16-2014
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Photoperiod is a major environmental cue that signals breeding conditions in animals living in temperate climates. Therefore, the activity of the reproductive (i.e. hypothalamic-pituitary-gonadal, HPG) axis and of the expression of reproductive behaviors, including territoriality, is responsive to changes in day length. However, at low latitudes the seasonal variation in day length decreases dramatically and photoperiod becomes less reliable as a breeding entraining cue in tropical species. In spite of this, some tropical mammals and birds have been found to still respond to small amplitude changes in photoperiod (e.g. 17min). Here we tested the effect of 2 photoperiod regimes, referred to as long-day (LD: 16L:08D) and short-day (SD: 08L:16D), on the activity of the HPG axis, on aggressive behavior and in the androgen response to social challenges in males of the tropical cichlid fish Tilapia rendalli. For each treatment, fish were transferred from a pre-treatment photoperiod of 12L:12D to their treatment photoperiod (either LD or SD) in which they were kept for 20days on stock tanks. Afterwards, males were isolated for 4days in glass aquaria in order to establish territories and initial androgen levels (testosterone, T; 11-ketotestosterone, KT) were assessed. On the 4th day, territorial intrusions were promoted such that 1/3 of the isolated males acted as residents and another 1/3 as intruders. Territorial intrusions lasted for 1h to test the effects of a social challenge under different photoperiod regimes. Photoperiod treatment (either SD or LD) failed to induce significant changes in the HPG activity, as measured by androgen levels and gonadosomatic index. However, SD increased the intensity of aggressive behaviors and shortened the time to settle a dominance hierarchy in an androgen-independent manner. The androgen responsiveness to the simulated territorial intrusion was only present in KT but not for T. The percent change in KT levels in response to the social challenge was different between treatments (SD>LD) and between male types (resident>intruder). The higher androgen response to a social challenge in residents under SD may be explained by the time course of the androgen response that due to the long time it takes to fight resolution under LD, might have been delayed. This result illustrates the importance of incorporating time response data in social endocrinology studies.
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Diversity and Persistence of Ectomycorrhizal Fungi and Their Effect on Nursery-Inoculated Pinus pinaster in a Post-fire Plantation in Northern Portugal.
Microb. Ecol.
PUBLISHED: 06-16-2014
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Ectomycorrhizal fungi (ECMF) play an important role in forest ecosystems, often mitigating stress factors and increasing seedling performance. The aim of this study was to investigate the effects of a nursery inoculation on Pinus pinaster growth and on the fungal communities established when reforesting burned areas. Inoculated P. pinaster saplings showed 1.5-fold higher stem height than the non-inoculated controls after a 5 year growth period, suggesting that fungal inoculation could potentiate tree growth in the field. Ordination analysis revealed the presence of different ECMF communities on both plots. Among the nursery-inoculated fungi, Laccaria sp., Rhizopogon sp., Suillus bovinus and Pisolithus sp. were detected on inoculated Pinus saplings on both sampling periods, indicating that they persisted after field establishment. Other fungi were also detected in the inoculated plants. Phialocephala sp. was found on the first assessment, while Terfezia sp. was detected on both sampling periods. Laccaria sp. and Rhizopogon sp. were identified in the control saplings, belonging however to different species than those found in the inoculated plot. Inocybe sp., Thelephora sp. and Paxillus involutus were present on both sampling periods in the non-inoculated plots. The results suggest that ECMF inoculation at nursery stage can benefit plant growth after transplantation to a post-fire site and that the inoculated fungi can persist in the field. This approach has great potential as a biotechnological tool to aid in the reforestation of burned areas.
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Social instability promotes hormone-behavior associated patterns in a cichlid fish.
Horm Behav
PUBLISHED: 05-13-2014
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Androgens are known to respond to social challenges and to control the expression of social behavior and reproductive traits, such as gonadal maturation and sperm production, expression of secondary sex characters and reproductive behaviors. According to the challenge hypothesis variation in androgen levels above a breeding baseline should be explained by the regime of social challenges faced by the individual considering the trade-offs of androgens with other traits (e.g. parental care). One prediction that can be derived from the challenge hypothesis is that androgen levels should increase in response to social instability. Moreover, considering that a tighter association of relevant traits is expected in periods of environmental instability, we also predict that in unstable environments the degree of correlations among different behaviors should increase and hormones and behavior should be associated. These predictions were tested in a polygamous cichlid fish (Mozambique tilapia, Oreochromis mossambicus) with exclusive maternal care. Social instability was produced by swapping dominant males among groups. Stable treatment consisted in removing and placing back dominant males in the same group, in order to control for handling stress. Cortisol levels were also measured to monitor stress levels involved in the procedure and their relation to the androgen patterns and behavior. As predicted androgen levels increased in males in response to the establishment of a social hierarchy and presence of receptive females. However, there were no further differential increases in androgen levels over the social manipulation phase between social stable and social unstable groups. As predicted behaviors were significantly more correlated among themselves in the unstable than in the stable treatment and an associated hormone-behavior pattern was only observed in the unstable treatment.
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Clinical and biochemical assessment of maintenance treatment in chronic recurrent seborrheic dermatitis: randomized controlled study.
Dermatol Ther (Heidelb)
PUBLISHED: 03-19-2014
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Few studies have investigated the long-term effects of a maintenance regimen in the prevention of relapses in scalp seborrheic dermatitis (SD), in particular following biomarker changes.
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Bionanoconjugation for Proteomics applications - An overview.
Biotechnol. Adv.
PUBLISHED: 03-15-2014
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Formed as an interdisciplinary domain on the basis of Human Genome Project, Proteomics aims at the large-scale study of proteins. The enthusiasm that resulted from obtaining the complete human genetic information has, however, been chastened by the realization that this information contributes little to the comprehension and knowledge of the expressed proteins. In the wake of this realization, the Human Proteome Project (HUPO) was founded, which is a global, collaborative initiative, aiming at the complete characterization of the proteins of all protein-coding genes. Nonetheless, the rapid detection of these molecules in complex biological samples under conditions considered to be of clinical relevance is extremely difficult, requiring the development of very sensitive, robust, reproducible and high throughput platforms. Nanoproteomics has emerged as a feasible, promising option, offering short assay times, low sample consumption, ultralow detection and high throughput capacity. Additionally, the successful synthesis of biomolecules and nanoparticle hybrids yields systems which often exhibit new or improved features. Herein, we overview the recent advances in bioconjugation at the nanolevel and, specifically, their application in Proteomics, discussing not only the merits and prospects of Proteomics, but also present day limitations.
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Castration affects reproductive but not aggressive behavior in a cichlid fish.
Gen. Comp. Endocrinol.
PUBLISHED: 03-15-2014
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Gonads are the main source of sex steroids, which have been implicated in the regulation of sexually differentiated behavior, such as reproductive and aggressive displays. In the Mozambique tilapia (Oreochromis mossambicus) territorial males have higher androgen levels than non-territorials, express reproductive behavior and use a urine-borne pheromone to signal their social status towards conspecifics. Here we investigated the effects of gonadectomy on the circulating levels of androgens and cortisol, and on the expression of aggressive and reproductive behavior (nest building, courtship behavior, and nuptial coloration). Males were either castrated, urine bladder damaged, or sham-operated and visually exposed to a group of females during 8 consecutive days and subsequently to a male on day 9. The urine bladder damaged treatment was included in the experimental design because a full castration procedure in this species causes quite often damage to the urine bladder. Gonadectomy lowers dramatically the circulating levels of androgens measured at 4 and 8days post-castration and abolishes the expression of nest building, courtship behavior and nuptial coloration, but has no effect on the expression of aggressive behavior. These results confirm the gonads as the main source of androgens in this species and show that androgens are necessary for the expression of reproductive behaviors. However, the expression of aggressive behavior seems to be decoupled from gonadal steroids, namely androgens, suggesting the action of independent central mechanisms.
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Aging related changes in mixed Basal saliva concentration of sodium, potassium and chloride in healthy non medicated humans.
Curr Aging Sci
PUBLISHED: 02-18-2014
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It is well known that the salivary flow is reduced by aging but ionic composition changes associated to aging have been less evaluated. To measure salivary and plasmatic [Na(+)], [K(+)] and [Cl(-)] and to correlate with age in healthy, non-medicated subjects of any gender, 165 healthy participating subjects (over 15 years old) were asked to give sample of 5mL mix basal saliva in a plastic vial without any stimulation technique, additionally, 5mL of venous blood was collected. Samples [Na(+)] and [K(+)] were measured by flame photometry (Corning(TM) M-405) and [Cl(-)] by voltametric chlorometry (Corning(TM) M-920). Ionic concentrations were expressed as (X±DE; meq.L-1). All three ionic concentrations progresively increased with age, with the lineal regression equation being: [Na(+)] mEq=17.76 + 0.26(Age); r=+0.42; F=31.5; P=0.00001; [K(+)] mEq=13.2+0.15(Age); r=+0.32; F=16.5; P=0.00001; [Cl(-)] mEq=9.05+0.18(Age); r=+0.35; F=7.8; P=0.0071. Age induced changes in salivary ionic concentrations were not associated to blood ionic changes. However, saliva and blood [Na(+)] and [K(+)] were correlated (r=+0.25; F=4.49; P=0.04 and r=+0.30; F=6.98; P=0.01, respectively). Significant association was found among salivary ions: [Na(+)] mEq=9.14+0.99[K(+)] (r=+0.79; F=95.2; P=0.000001); [Cl(-)] mEq=0.95+0.56[Na(+)] (r=0.79; F=106.6; P=0.000001) and [Cl(-)] mEq=3.45+0.69[K(+)] (r=0.73; F=72.5; P=0.000001). These results confirm and measure the impact of aging over the mixed and resting salivary secretion process and suggest that local changes are not related to blood ionic composition.
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Effect of corn steep liquor (CSL) and cassava wastewater (CW) on chitin and chitosan production by Cunninghamella elegans and their physicochemical characteristics and cytotoxicity.
Molecules
PUBLISHED: 02-14-2014
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Microbiological processes were used for chitin and chitosan production with Cunninghamella elegans UCP/WFCC 0542 grown in different concentrations of two agro-industrial wastes, corn steep liquor (CSL) and cassava wastewater (CW) established using a 2² full factorial design. The polysaccharides were extracted by alkali-acid treatment and characterized by infrared spectroscopy, viscosity, thermal analysis, elemental analysis, scanning electron microscopy and X-ray diffraction. The cytotoxicity of chitosan was evaluated for signs of vascular change on the chorioallantoic membrane of chicken eggs. The highest biomass (9.93 g/L) was obtained in trial 3 (5% CW, 8% CSL), the greatest chitin and chitosan yields were 89.39 mg/g and 57.82 mg/g, respectively, and both were obtained in trial 2 (10% CW, 4% CSL). Chitin and chitosan showed a degree of deacetylation of 40.98% and 88.24%, and a crystalline index of 35.80% and 23.82%, respectively, and chitosan showed low molecular weight (LMW 5.2 × 10³ Da). Chitin and chitosan can be considered non-irritating, due to the fact they do not promote vascular change. It was demonstrated that CSL and CW are effective renewable agroindustrial alternative substrates for the production of chitin and chitosan.
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A quality study to improve prophylactic antithrombotic therapy prescribed to patients with atrial fibrillation.
Rev Port Cardiol
PUBLISHED: 02-02-2014
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Atrial fibrillation is the most common cardiac arrhythmia and has important clinical repercussions, increasing thromboembolic events and mortality. The CHA2DS2-VASc and HAS-BLED scores assist the clinician in assessing the benefits and risks of antithrombotic therapy.
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Mental health literacy about schizophrenia: a survey of Portuguese youth.
Early Interv Psychiatry
PUBLISHED: 01-21-2014
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Mental health literacy about psychotic disorders, specifically schizophrenia, may assist in appropriate help seeking and early intervention, preventing the exacerbation of symptoms and improving health outcomes in the medium and long term. The aim of this study was to characterize the level of mental health literacy of Portuguese youth concerning schizophrenia.
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Cortisol mediates cleaner wrasse switch from cooperation to cheating and tactical deception.
Horm Behav
PUBLISHED: 01-16-2014
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Recent empirical research, mostly done on humans, recognizes that individuals' physiological state affects levels of cooperation. An individual's internal state may affect the payoffs of behavioural alternatives, which in turn could influence the decision to either cooperate or to defect. However, little is known about the physiology underlying condition dependent cooperation. Here, we demonstrate that shifts in cortisol levels affect levels of cooperation in wild cleaner wrasse Labroides dimidiatus. These cleaners cooperate by removing ectoparasites from visiting 'client' reef fishes but prefer to eat client mucus, which constitutes cheating. We exogenously administrated one of three different compounds to adults, that is, (a) cortisol, (b) glucocorticoid receptor antagonist mifepristone RU486 or (c) sham (saline), and observed their cleaning behaviour during the following 45min. The effects of cortisol match an earlier observational study that first described the existence of "cheating" cleaners: such cleaners provide small clients with more tactile stimulation with their pectoral and pelvic fins, a behaviour that attracts larger clients that are then bitten to obtain mucus. Blocking glucocorticoid receptors led to more tactile stimulation to large clients. As energy demands and associated cortisol concentration level shifts affect cleaner wrasse behavioural patterns, cortisol potentially offers a general mechanism for condition dependent cooperation in vertebrates.
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Hybrid modeling for quality by design and PAT-benefits and challenges of applications in biopharmaceutical industry.
Biotechnol J
PUBLISHED: 01-12-2014
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This report highlights the drivers, challenges, and enablers of the hybrid modeling applications in biopharmaceutical industry. It is a summary of an expert panel discussion of European academics and industrialists with relevant scientific and engineering backgrounds. Hybrid modeling is viewed in its broader sense, namely as the integration of different knowledge sources in form of parametric and nonparametric models into a hybrid semi-parametric model, for instance the integration of fundamental and data-driven models. A brief description of the current state-of-the-art and industrial uptake of the methodology is provided. The report concludes with a number of recommendations to facilitate further developments and a wider industrial application of this modeling approach. These recommendations are limited to further exploiting the benefits of this methodology within process analytical technology (PAT) applications in biopharmaceutical industry.
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The importance of novelty: male-female interactions among blue-black grassquits in captivity.
Behav. Processes
PUBLISHED: 01-07-2014
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Mate choice is a primary mechanism driving the evolution of sexually selected traits such as elaborate displays and ornaments. In a majority of taxa studied to date, females are seen to actively sample and evaluate multiple males, presumably to optimize mating opportunities. During this process females may encounter males both familiar and novel, a distinction that might influence how mate choice proceeds. Using a socially monogamous passerine, the blue-black grassquit (Volatinia jacarina), we studied how females respond to novel versus familiar ("paired") males, and how encounters with novel males influence subsequent interactions with their paired males. Additionally, we measured the hormonal response of males after visualizing their paired females interacting with novel males. We found that females were attentive to novel males irrespective of these males' phenotypic attributes, suggesting that in these interactions novelty is highly relevant. After exposure to novel males, females tended to respond aggressively towards their paired males; by contrast, the behaviour of males towards their paired females did not change. Moreover, we did not detect any hormonal responses of males to viewing their paired females interacting with novel males. Together these results suggest that the distinction between familiarity and novelty may hold special relevance for females in mate choice, a finding that bears upon our understanding of the evolution of extra-pair paternity and reproductive behaviour.
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Testosterone response to competition in males is unrelated to opponent familiarity or threat appraisal.
Front Psychol
PUBLISHED: 01-01-2014
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It has been proposed in the literature that the testosterone (T) response to competition in humans may be modulated by cognitive variables. In a previous experiment with a female sample we have reported that opponent familiarity and threat appraisal moderated the T response to competition in women. With this experiment we aim to investigate if these variables have the same impact on males T response to competition, extending the previous findings in our lab. Forty male participants (20 dyads) were recruited to engage in a same sex, face to face competition using the Number Tracking Test as a competitive task. Levels of T, cortisol (C) and dehydroepiandrosterone (DHEA) were measured before and 20 min after the competition. Results show that losers report higher levels of threat than winners and increased their T levels after the competition, however this T change was not predicted by opponent familiarity or threat appraisal. No variation was detected for C and DHEA levels. These findings suggest that there could be sex differences for the moderators/mediators of the T response to competition in humans.
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Behavioural stress responses predict environmental perception in European sea bass (Dicentrarchus labrax).
PLoS ONE
PUBLISHED: 01-01-2014
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Individual variation in the response to environmental challenges depends partly on innate reaction norms, partly on experience-based cognitive/emotional evaluations that individuals make of the situation. The goal of this study was to investigate whether pre-existing differences in behaviour predict the outcome of such assessment of environmental cues, using a conditioned place preference/avoidance (CPP/CPA) paradigm. A comparative vertebrate model (European sea bass, Dicentrarchus labrax) was used, and ninety juvenile individuals were initially screened for behavioural reactivity using a net restraining test. Thereafter each individual was tested in a choice tank using net chasing as aversive stimulus or exposure to familiar conspecifics as appetitive stimulus in the preferred or non preferred side respectively (called hereafter stimulation side). Locomotor behaviour (i.e. time spent, distance travelled and swimming speed in each tank side) of each individual was recorded and analysed with video software. The results showed that fish which were previously exposed to appetitive stimulus increased significantly the time spent on the stimulation side, while aversive stimulus led to a strong decrease in time spent on the stimulation side. Moreover, this study showed clearly that proactive fish were characterised by a stronger preference for the social stimulus and when placed in a putative aversive environment showed a lower physiological stress responses than reactive fish. In conclusion, this study showed for the first time in sea bass, that the CPP/CPA paradigm can be used to assess the valence (positive vs. negative) that fish attribute to different stimuli and that individual behavioural traits is predictive of how stimuli are perceived and thus of the magnitude of preference or avoidance behaviour.
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Androgen modulation of social decision-making mechanisms in the brain: an integrative and embodied perspective.
Front Neurosci
PUBLISHED: 01-01-2014
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Apart from their role in reproduction androgens also respond to social challenges and this response has been seen as a way to regulate the expression of behavior according to the perceived social environment (Challenge hypothesis, Wingfield et al., 1990). This hypothesis implies that social decision-making mechanisms localized in the central nervous system (CNS) are open to the influence of peripheral hormones that ultimately are under the control of the CNS through the hypothalamic-pituitary-gonadal axis. Therefore, two puzzling questions emerge at two different levels of biological analysis: (1) Why does the brain, which perceives the social environment and regulates androgen production in the gonad, need feedback information from the gonad to adjust its social decision-making processes? (2) How does the brain regulate gonadal androgen responses to social challenges and how do these feedback into the brain? In this paper, we will address these two questions using the integrative approach proposed by Niko Tinbergen, who proposed that a full understanding of behavior requires its analysis at both proximate (physiology, ontogeny) and ultimate (ecology, evolution) levels.
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Mini-arc for the treatment of female stress urinary incontinence: long-term prospective evaluation by patient reported outcomes.
ISRN Urol
PUBLISHED: 01-01-2014
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Single-incision slings were introduced in the surgical treatment of female stress urinary incontinence (SUI) to lessen the morbidity associated with traditional midurethral slings. However, long-term reports on patient satisfaction are still scarce. This study describes the outcome of women treated with Mini-Arc at a mean follow-up of 45 months. In a previous report on 105 women with 15-month mean follow-up, 84 (80%) were found cured and 12 (11%) improved. Now, with a mean follow-up of 45 months, cured/improved patients were reassessed by telephone and completed Patient Global Impression of Improvement (PGI-I), Patient Global Impression of Severity (PGI-S), rated their improvement in a 0-100 scale, and answered if they would recommend the procedure. At 45-month follow-up, 73 women cured/improved were available for evaluation. Over 80% of the cured patients rated the improvement of SUI by the PGI-I as "very much better" or "much better," reported their urinary tract condition to be "normal" on PGI-S, and described their improvement >70%. Ninety percent would recommend this procedure to a friend. The improved-patient population is very small (n = 7). This study shows that the majority of patients cured/improved after Mini-Arc placement maintain a high degree of satisfaction at a long-term evaluation.
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Participation of Candida albicans transcription factor RLM1 in cell wall biogenesis and virulence.
PLoS ONE
PUBLISHED: 01-01-2014
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Candida albicans cell wall is important for growth and interaction with the environment. RLM1 is one of the putative transcription factors involved in the cell wall integrity pathway, which plays an important role in the maintenance of the cell wall integrity. In this work we investigated the involvement of RLM1 in the cell wall biogenesis and in virulence. Newly constructed C. albicans ?/?rlm1 mutants showed typical cell wall weakening phenotypes, such as hypersensitivity to Congo Red, Calcofluor White, and caspofungin (phenotype reverted in the presence of sorbitol), confirming the involvement of RLM1 in the cell wall integrity. Additionally, the cell wall of C. albicans ?/?rlm1 showed a significant increase in chitin (213%) and reduction in mannans (60%), in comparison with the wild-type, results that are consistent with cell wall remodelling. Microarray analysis in the absence of any stress showed that deletion of RLM1 in C. albicans significantly down-regulated genes involved in carbohydrate catabolism such as DAK2, GLK4, NHT1 and TPS1, up-regulated genes involved in the utilization of alternative carbon sources, like AGP2, SOU1, SAP6, CIT1 or GAL4, and genes involved in cell adhesion like ECE1, ALS1, ALS3, HWP1 or RBT1. In agreement with the microarray results adhesion assays showed an increased amount of adhering cells and total biomass in the mutant strain, in comparison with the wild-type. C. albicans mutant ?/?rlm1 strain was also found to be less virulent than the wild-type and complemented strains in the murine model of disseminated candidiasis. Overall, we showed that in the absence of RLM1 the modifications in the cell wall composition alter yeast interaction with the environment, with consequences in adhesion ability and virulence. The gene expression findings suggest that this gene participates in the cell wall biogenesis, with the mutant rearranging its metabolic pathways to allow the use of alternative carbon sources.
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Oestradiol and prostaglandin F2? regulate sexual displays in females of a sex-role reversed fish.
Proc. Biol. Sci.
PUBLISHED: 01-01-2014
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The mechanisms regulating sexual behaviours in female vertebrates are still poorly understood, mainly because in most species sexual displays in females are more subtle and less frequent than displays in males. In a sex-role reversed population of a teleost fish, the peacock blenny Salaria pavo, an external fertilizer, females are the courting sex and their sexual displays are conspicuous and unambiguous. We took advantage of this to investigate the role of ovarian-synthesized hormones in the induction of sexual displays in females. In particular, the effects of the sex steroids oestradiol (E2) and testosterone (T) and of the prostaglandin F2? (PGF2?) were tested. Females were ovariectomized and their sexual behaviour tested 7 days (sex steroids and PGF2?) and 14 days (sex steroids) after ovariectomy by presenting females to an established nesting male. Ovariectomy reduced the expression of sexual behaviours, although a significant proportion of females still courted the male 14 days after the ovary removal. Administration of PGF2? to ovariectomized females recovered the frequency of approaches to the male's nest and of courtship displays towards the nesting male. However, E2 also had a positive effect on sexual behaviour, particularly on the frequency of approaches to the male's nest. T administration failed to recover sexual behaviours in ovariectomized females. These results suggest that the increase in E2 levels postulated to occur during the breeding season facilitates female mate-searching and assessment behaviours, whereas PGF2? acts as a short-latency endogenous signal informing the brain that oocytes are mature and ready to be spawned. In the light of these results, the classical view for female fishes, that sex steroids maintain sexual behaviour in internal fertilizers and that prostaglandins activate spawning behaviours in external fertilizers, needs to be reviewed.
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High ultraviolet C resistance of marine Planctomycetes.
Antonie Van Leeuwenhoek
PUBLISHED: 07-09-2013
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Planctomycetes are bacteria with particular characteristics such as internal membrane systems encompassing intracellular compartments, proteinaceous cell walls, cell division by yeast-like budding and large genomes. These bacteria inhabit a wide range of habitats, including marine ecosystems, in which ultra-violet radiation has a potential harmful impact in living organisms. To evaluate the effect of ultra-violet C on the genome of several marine strains of Planctomycetes, we developed an easy and fast DNA diffusion assay in which the cell wall was degraded with papain, the wall-free cells were embedded in an agarose microgel and lysed. The presence of double strand breaks and unwinding by single strand breaks allow DNA diffusion, which is visible as a halo upon DNA staining. The number of cells presenting DNA diffusion correlated with the dose of ultra-violet C or hydrogen peroxide. From DNA damage and viability experiments, we found evidence indicating that some strains of Planctomycetes are significantly resistant to ultra-violet C radiation, showing lower sensitivity than the known resistant Arthrobacter sp. The more resistant strains were those phylogenetically closer to Rhodopirellula baltica, suggesting that these species are adapted to habitats under the influence of ultra-violet radiation. Our results provide evidence indicating that the mechanism of resistance involves DNA damage repair and/or other DNA ultra-violet C-protective mechanism.
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Design of pathway-level bioprocess monitoring and control strategies supported by metabolic networks.
Adv. Biochem. Eng. Biotechnol.
PUBLISHED: 06-29-2013
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In this chapter we explore the basic tools for the design of bioprocess monitoring, optimization, and control algorithms that incorporate a priori knowledge of metabolic networks. The main advantage is that this ultimately enables the targeting of intracellular control variables such as metabolic reactions or metabolic pathways directly linked with productivity and product quality. We analyze in particular design methods that target elementary modes of metabolic networks. The topics covered include the analysis of the structure of metabolic networks, computation and reduction of elementary modes, measurement methods for the envirome, envirome-guided metabolic reconstruction, and macroscopic dynamic modeling and control. These topics are illustrated with applications to a cultivation process of a recombinant Pichia pastoris X33 strain expressing a single-chain antibody fragment (scFv).
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Social modulation of brain monoamine levels in zebrafish.
Behav. Brain Res.
PUBLISHED: 05-21-2013
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In social species animals tend to adjust their social behaviour according to the available social information in the group, in order to optimize and improve their one social status. This changing environment requires for rapid and transient behavioural changes that relies primarily on biochemical switching of existing neural networks. Monoamines and neuropeptides are the two major candidates to mediate these changes in brain states underlying socially behavioural flexibility. In the current study we used zebrafish (Danio rerio) males to study the effects of acute social interactions on rapid regional changes in brain levels of monoamines (serotonin and dopamine). A behavioural paradigm under which male zebrafish consistently express fighting behaviour was used to investigate the effects of different social experiences: winning the interaction, losing the interaction, or fighting an unsolved interaction (mirror image). We found that serotonergic activity is significantly higher in the telencephalon of winners and in the optic tectum of losers, and no significant changes were observed in mirror fighters suggesting that serotonergic activity is differentially regulated in different brain regions by social interactions. Dopaminergic activity it was also significantly higher in the telencephalon of winners which may be representative of social reward. Together our data suggests that acute social interactions elicit rapid and differential changes in serotonergic and dopaminergic activity across different brain regions.
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Arginine vasotocin neuronal phenotype and interspecific cooperative behaviour.
Brain Behav. Evol.
PUBLISHED: 04-25-2013
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The nonapeptide arginine vasotocin (AVT) and its mammalian homologue arginine vasopressin are well known for their role in the modulation of several intraspecific social behaviours, such as social approach/withdrawal and aggression. Recently, we suggested that AVT might also be important in the regulation of interspecific social behaviours as it modulates interspecific cooperative behaviours in the Indo-Pacific bluestreak cleaner wrasse Labroides dimidiatus. AVT injections decreased cleaners propensity to engage in cleaning interactions with their clients, suggesting that high levels of this peptide compromise the cleaners cooperative motivation. Therefore, we hypothesise that low endogenous levels of AVT are a prerequisite for the expression of interspecific cleaning behaviour in cleaner wrasses, since it allows them to approach and interact with interspecific individuals, and that this should be reflected in their AVT neuronal phenotype. Here we test this hypothesis by comparing the AVT neuronal phenotypes of two phylogenetically closely related species that live in similar environments but diverge in the expression of interspecific cooperative behaviour: an obligate cleaner wrasse (L. dimidiatus) and a non-cleaner corallivore wrasse (Labrichthys unilineatus). The two species are predicted to differ in their AVT neuronal phenotypes as a reflection of their ability/inability to approach and interact with interspecific individuals, with cleaners presenting smaller and/or less numerous AVT-immunoreactive (ir) neurons. A sex difference in AVT neuronal phenotypes was also predicted because males of both species appear to be more aggressive than females. As described for most of the other teleost species, AVT-ir neurons were restricted to the preoptic area, and in agreement with our first prediction cleaners presented smaller and less numerous AVT-ir neurons in the gigantocellular preoptic area (gPOA) compared to non-cleaners. Contrary to our second prediction, AVT neuronal phenotypes did not differ between sexes in either species, but differences in other features of the AVT system cannot be ruled out. In summary, the results presented here suggest a putative role for AVT gPOA neurons in the ability of a cleaner wrasse to approach and interact with a client, through their projections to extrahypothalamic brain areas.
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Noninvasive measurement of steroid hormones in zebrafish holding-water.
Zebrafish
PUBLISHED: 02-27-2013
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Zebrafish (Danio rerio) has recently emerged as a new animal model in neuroendocrinology and behavior (e.g., stress physiology and ecotoxicology studies). In these areas, the concentrations of steroid hormones in the blood are often used to study the endocrinological status of individuals. However, due to the small body size of zebrafish, blood sampling is difficult to perform and the amount of plasma obtained per sample for assaying hormones is very small (ca. 1-5??L), and therefore most studies have been using whole-body hormone concentrations, which implies sacrificing the individuals and hampers sequential sampling of the same individual. Here a noninvasive method to assay steroid hormones from zebrafish holding-water, based on the fact that steroids are released into the fish holding-water through the gills by passive diffusion, is validated. Cortisol and the androgen 11-ketotestosterone (KT) were measured in water samples and compared to plasma levels in the same individuals. Cortisol released to holding-water correlates positively with plasma concentrations, but there was a lack of correlation between KT water and circulating levels. However, KT levels showed a highly significant sex difference that can be used to noninvasively sex individuals. An ACTH challenge test demonstrated that an induced increase in circulating cortisol concentration can be reliably detected in holding-water levels, hence attesting the responsiveness of holding-water levels to fluctuations in circulating levels.
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Fast development of Pichia pastoris GS115 Mut(+) cultures employing batch-to-batch control and hybrid semi-parametric modeling.
Bioprocess Biosyst Eng
PUBLISHED: 02-19-2013
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In this paper, we implemented a model-based optimization platform for fast development of Pichia pastoris cultures employing batch-to-batch control and hybrid semi-parametric modeling. We illustrate the methodology with a P. pastoris GS115 strain expressing a single-chain antibody fragment (scFv) by determining the optimal time profiles of temperature, pH, glycerol feeding and methanol feeding that maximize the endpoint scFv titer. The first hybrid model was identified from data of six exploratory experiments carried out in a pilot 50-L reactor. This model was subsequently used to maximize the final scFv titer of the proceeding batch employing a dynamic optimization program. Thereupon, the optimized time profiles of control variables were implemented in the pilot reactor and the resulting new data set was used to re-identify the hybrid model and to re-optimize the next batch. The iterative batch-to-batch optimization was stopped after 4 complete optimized batches with the final scFv titer stabilizing at 49.5 mg/L. In relation to the baseline batch (executed according to the Pichia fermentation guidelines by Invitrogen) a more than fourfold increase in scFv titer was achieved. The biomass concentration at induction and the methanol feeding rate profile were found to be the most critical control degrees of freedom to maximize scFv titer.
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Modeling NOM removal by softening in a surface water treatment plant.
Water Sci. Technol.
PUBLISHED: 02-19-2013
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Phenomenological models and hybrid phenomenological-chemometric models were developed to predict natural organic matter (NOM) removal based on the real water treatment data from the city of Minneapolis over a 3 year period. The analysis of the modeling results showed that the phenomenological model was able to capture the major variations of NOM removal but it tended to over predict the NOM removal in independent data sets. These results could be significantly improved by the hybrid model, which was less biased and much more accurate than the phenomenological model. The phenomenological model parameters showed low statistical confidence because the available data, collected in real water treatment conditions, was not sufficiently informative to identify the complex model structure. By comparison, the hybrid modeling method enabled a more reliable discrimination of the most important factors affecting NOM removal. The final hybrid model was implemented in an Excel spreadsheet and can be easily used for NOM removal prediction and the control of chemical dosing.
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Efficient isolation of polymorphic microsatellites from high-throughput sequence data based on number of repeats.
Mar Genomics
PUBLISHED: 02-04-2013
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Transcriptome data are a good resource to develop microsatellites due to their potential in targeting candidate genes. However, developing microsatellites can be a time-consuming enterprise due to the numerous primer pairs to be tested. Therefore, the use of methodologies that make it efficient to identify polymorphic microsatellites is desirable. Here we used a 62,038 contigs transcriptome assembly, obtained from pyrosequencing a peacock blenny (Salaria pavo) multi-tissue cDNA library, to mine for microsatellites and in silico evaluation of their polymorphism. A total of 4190 microsatellites were identified in 3670 unique unigenes, and from these microsatellites, in silico polymorphism was detected in 733. We selected microsatellites based either on their in silico polymorphism and annotation results or based only on their number of repeats. Using these two approaches, 28 microsatellites were successfully amplified in twenty-six individuals, and all but 2 were found to be polymorphic, being the first genetic markers for this species. Our results showed that the strategy of selection based on number of repeats is more efficient in obtaining polymorphic microsatellites than the strategy of in silico polymorphism (allelic richness was 8.2±3.85 and 4.56±2.45 respectively). This study demonstrates that combining the knowledge of number of repeats with other predictors of variability, for example in silico microsatellite polymorphism, improves the rates of polymorphism, yielding microsatellites with higher allelic richness, and decreases the number of monomorphic microsatellites obtained.
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Dynamic metabolic modelling of volatile fatty acids conversion to polyhydroxyalkanoates by a mixed microbial culture.
N Biotechnol
PUBLISHED: 01-18-2013
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In this work, we present a dynamic metabolic model that describes the uptake of complex mixtures of volatile fatty acids (VFA) and respective conversion into PHA by mixed microbial cultures (MMC). This model builds upon a previously published flux balance analysis model [1] that identified the minimization of TCA cycle activity as the key metabolic objective to predict PHA storage fluxes and respective composition. The model was calibrated either with experimental data of PHA production from fermented sugar cane molasses or from synthetic mixtures of VFA. All PHA production experiments were performed using a MMC selected with fermented sugar cane molasses under feast and famine regimen. The model was able to capture the process dynamics denoted by an excellent fit between experimental and computed time profiles of concentrations with the regression coefficients always above 0.92. The introduced VFA uptake regulatory factor reflects the decrease of acetyl-CoA and propionyl-CoA available to TCA cycle in conformity with the hypothesis that the minimization of TCA cycle is a key metabolic objective for MMC subjected to feast and famine regimen for the maximization of PHA production.
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Mind the fish: zebrafish as a model in cognitive social neuroscience.
Front Neural Circuits
PUBLISHED: 01-01-2013
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Understanding how the brain implements social behavior on one hand, and how social processes feedback on the brain to promote fine-tuning of behavioral output according to changes in the social environment is a major challenge in contemporary neuroscience. A critical step to take this challenge successfully is finding the appropriate level of analysis when relating social to biological phenomena. Given the enormous complexity of both the neural networks of the brain and social systems, the use of a cognitive level of analysis (in an information processing perspective) is proposed here as an explanatory interface between brain and behavior. A conceptual framework for a cognitive approach to comparative social neuroscience is proposed, consisting of the following steps to be taken across different species with varying social systems: (1) identification of the functional building blocks of social skills; (2) identification of the cognitive mechanisms underlying the previously identified social skills; and (3) mapping these information processing mechanisms onto the brain. Teleost fish are presented here as a group of choice to develop this approach, given the diversity of social systems present in closely related species that allows for planned phylogenetic comparisons, and the availability of neurogenetic tools that allows the visualization and manipulation of selected neural circuits in model species such as the zebrafish. Finally, the state-of-the art of zebrafish social cognition and of the tools available to map social cognitive abilities to neural circuits in zebrafish are reviewed.
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Threat perception and familiarity moderate the androgen response to competition in women.
Front Psychol
PUBLISHED: 01-01-2013
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Social interactions elicit androgen responses whose function has been posited to be the adjustment of androgen-dependent behaviors to social context. The activation of this androgen response is known to be mediated and moderated by psychological factors. In this study we tested the hypothesis that the testosterone (T) changes after a competition are not simply related to its outcome, but rather to the way the subject evaluates the event. In particular we tested two evaluative dimensions of a social interaction: familiarity with the opponent and the subjective evaluation of the outcome as threat or challenge. Challenge/threat occurs in goal relevant situations and represent different motivational states arising from the individuals subjective evaluation of the interplay between the task demands and coping resources possessed. For challenge the coping resources exceed the task demands, while threat represents a state where coping resources are insufficient to meet the task demands. In this experiment women competed in pairs, against a same sex opponent using the number tracking test as a competitive task. Losers appraised the competition outcome as more threatening than winners, and displayed higher post-competition T levels than winners. No differences were found either for cortisol (C) or for dehydroepiandrosterone. Threat, familiarity with the opponent and T response were associated only in the loser condition. Moderation analysis suggests that for the women that lost the competition the effect of threat on T is moderated by familiarity with the opponent.
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Shark island pedicle flap for repairing of basal cell carcinoma localized in nasal ala-perialar region: a simple procedure.
An Bras Dermatol
PUBLISHED: 11-10-2011
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Basal Cell Carcinoma is the most common skin cancer. We describe a single-staged technique for correction of nasal ala defect after the excision of a basal cell carcinoma. This technique allows correction of surgical defects of the ala rebuilding the original anatomy, maintaining cosmetic units, without need for a graft.
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Beyond the body image: a qualitative study on how adults experience lower limb amputation.
Clin Rehabil
PUBLISHED: 09-09-2011
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To explore adults experiences of lower limb amputation, focusing on the changes in self-identity related to the impairment.
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Brain levels of arginine-vasotocin and isotocin in dominant and subordinate males of a cichlid fish.
Horm Behav
PUBLISHED: 09-08-2011
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The nonapeptides arginine-vasotocin (AVT) and isotocin (IT), which are the teleost homologues of arginine-vasopressin and oxytocin in mammals, have well established peripheral effects on osmoregulation and stress response, and central effects on social behavior. However, all studies that have looked so far into the relationship between these nonapeptides and social behavior have used indirect measures of AVT/IT activity (i.e. immunohistochemistry of AVT/IT immunoreactive neurons, or AVT/IT or their receptors mRNA expression with in situ hybridization or qPCR) and therefore direct measures of peptide levels in relation to social behavior are still lacking. Here we use a recently developed high-performance liquid chromatography analysis with fluorescence detection (HPLC-FL) method to quantify the levels of both AVT and IT in macro-dissected brain areas [i.e. olfactory bulbs, telencephalon, diencephalon, optic tectum, cerebellum, and hindbrain (= rhombencephalon minus cerebellum)] and pituitary of dominant and subordinate male cichlid fish (Oreochromis mossambicus). The pituitary shows higher levels of both peptides than any of the brain macroareas, and the olfactory bulbs have the highest AVT among all brain areas. Except for IT in the telencephalon there is a lack of correlations between central levels and pituitary peptide levels, suggesting an independent control of hypophysial and CNS nonapeptide secretion. There were also no correlations between AVT and IT levels either for each brain region or for the pituitary gland, suggesting a decoupled activity of the AVT and IT systems at the CNS level. Subordinate AVT pituitary levels are significantly higher than those of dominants, and dominant hindbrain IT levels are significantly higher than those of subordinates, suggesting a potential involvement of AVT in social stress in subordinate fish and of IT in the regulation of dominant behavior at the level of the hindbrain. Since in this species dominant males use urine to communicate social status and since AVT is known to have an antidiuretic effect, we have also investigated the effect of social status on urine storage. As predicted, dominant males stored significantly more urine than subordinates. Given these results we suggest that AVT/IT play a key role in orchestrating social phenotypes, acting both as central neuromodulators that promote behavioral plasticity and as peripheral hormones that promote integrated physiological changes.
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From self-awareness to self-identification with visual impairment: a qualitative study with working age adults at a rehabilitation setting.
Clin Rehabil
PUBLISHED: 08-10-2011
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To explore the experience of vision loss, focusing on working age patients self-awareness of impairment and self-identification with the impairment.
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Tactile stimulation lowers stress in fish.
Nat Commun
PUBLISHED: 07-11-2011
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In humans, physical stimulation, such as massage therapy, reduces stress and has demonstrable health benefits. Grooming in primates may have similar effects but it remains unclear whether the positive effects are due to physical contact or to its social value. Here we show that physical stimulation reduces stress in a coral reef fish, the surgeonfish Ctenochaetus striatus. These fish regularly visit cleaner wrasses Labroides dimidiatus to have ectoparasites removed. The cleanerfish influences client decisions by physically touching the surgeonfish with its pectoral and pelvic fins, a behaviour known as tactile stimulation. We simulated this behaviour by exposing surgeonfish to mechanically moving cleanerfish models. Surgeonfish had significantly lower levels of cortisol when stimulated by moving models compared with controls with access to stationary models. Our results show that physical contact alone, without a social aspect, is enough to produce fitness-enhancing benefits, a situation so far only demonstrated in humans.
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Quantitative proteomics of Spodoptera frugiperda cells during growth and baculovirus infection.
PLoS ONE
PUBLISHED: 05-27-2011
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Baculovirus infection of Spodoptera frugiperda cells is a system of choice to produce a range of recombinant proteins, vaccines and, potentially, gene therapy vectors. While baculovirus genomes are well characterized, the genome of S. frugiperda is not sequenced and the virus-host molecular interplay is sparsely known. Herein, we describe the application of stable isotope labeling by amino acids in cell culture (SILAC) to obtain the first comparative proteome quantitation of S. frugiperda cells during growth and early baculovirus infection. The proteome coverage was maximized by compiling a search database with protein annotations from insect species. Of interest were differentially proteins related to energy metabolism, endoplasmic reticulum and oxidative stress, yet not investigated in the scope of baculovirus infection. Further, the reduced expression of key viral-encoded proteins early in the infection cycle is suggested to be related with decreased viral replication at high cell density culture. These findings have implications for virological research and improvement of baculovirus-based bioprocesses.
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Suburethral single incision slings in the treatment of female stress urinary incontinence: what is the evidence for using them in 2010?
Arch. Esp. Urol.
PUBLISHED: 05-26-2011
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To review the present evidence supporting the use of single-incision slings for treatment of female stress urinary incontinence.
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Fighting zebrafish: characterization of aggressive behavior and winner-loser effects.
Zebrafish
PUBLISHED: 05-25-2011
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Aggression is a key component of the behavioral repertoire of animals that impacts on their Darwinian fitness. The available genetic tools in zebrafish make this species a promising vertebrate neurogenetic model for the study of neural circuits underlying aggressive behavior. For this purpose, a detailed characterization of the aggressive behavior and its behavioral consequences is first needed. In this article we establish a simple protocol that reliably elicits the expression of fighting behavior in zebrafish dyads and characterized it. The agonistic behavior expressed during dyadic fighting behavior has a temporal structure, indicating the existence of an underlying architecture prone to genetic manipulation. Social interactions have consequences for subsequent behavior with a potential fitness impact, which stresses the validity of this species for the study of aggression. These effects of experience seem to be mediated by different mechanisms in winners and losers. Winners increase the probability of winning subsequent fights without changing their fighting behavior, suggesting the existence of social status cues. On the other hand, losers decrease the probability of winning subsequent fights by decreasing their motivation to escalate fights. Together, these results are a first step to the development of a quantitative framework for the study of aggressive behavior in zebrafish.
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Projection to latent pathways (PLP): a constrained projection to latent variables (PLS) method for elementary flux modes discrimination.
BMC Syst Biol
PUBLISHED: 05-09-2011
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Elementary flux modes (EFM) are unique and non-decomposable sets of metabolic reactions able to operate coherently in steady-state. A metabolic network has in general a very high number of EFM reflecting the typical functional redundancy of biological systems. However, most of these EFM are either thermodynamically unfeasible or inactive at pre-set environmental conditions.
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Single-incision sling system as primary treatment of female stress urinary incontinence: prospective 12 months data from a single institution.
BJU Int.
PUBLISHED: 04-01-2011
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To investigate the success and complication rates for Mini-Arc(TM) single incision sling in the treatment of female stress urinary incontinence (SUI).
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Attachment security and HPA axis reactivity to positive and challenging emotional situations in child-mother dyads in naturalistic settings.
Dev Psychobiol
PUBLISHED: 03-02-2011
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This study investigated adrenocortical activity in response to different challenging and positive affect emotional contexts in child-mother dyads, as function of attachment security (childrens secure base behaviors and mothers attachment representations). Fifty-one children ranging in age from 18 to 26 months and their mothers participated in this study. Secure children showed significant increases in their cortisol levels after fear episodes and significant decreases, after positive affect ones. No significant changes were found for frustration/anger episodes. Insecure children did not show significant differences in cortisol levels in any of the episodes, which suggests that insecure attachment may be related to hypothalamic-pituitary-adrenal axis suppression in response to challenging and positive contexts. Mothers of insecure children showed significantly higher cortisol concentrations in pre- and post-session samples, than mothers of secure children. Mothers personal attachment representations influenced their own cortisol responses, as well as their childrens (in a marginal significant way).
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Hybrid metabolic flux analysis: combining stoichiometric and statistical constraints to model the formation of complex recombinant products.
BMC Syst Biol
PUBLISHED: 02-25-2011
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Stoichiometric models constitute the basic framework for fluxome quantification in the realm of metabolic engineering. A recurrent bottleneck, however, is the establishment of consistent stoichiometric models for the synthesis of recombinant proteins or viruses. Although optimization algorithms for in silico metabolic redesign have been developed in the context of genome-scale stoichiometric models for small molecule production, still rudimentary knowledge of how different cellular levels are regulated and phenotypically expressed prevents their full applicability for complex product optimization.
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Sex differences in the dorsolateral telencephalon correlate with home range size in blenniid fish.
Brain Behav. Evol.
PUBLISHED: 02-16-2011
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Blenniid fish exhibit a polygynandric mating system with parental care restricted to males. Nest-holder males defend a breeding territory centered on their nest, usually a crevice or hole in a rocky substrate, to which they attract females to spawn. Females, on the other hand, must search for nests in order to spawn and usually are the choosy sex, producing several sequential egg batches and broods during the breeding season. Therefore, male blennies are more site-attached than females. This situation offers an opportunity to investigate potential neural correlates of intraspecific differences in selective pressures for different spatial abilities in these species. Since the dorsolateral telencephalon has been considered a teleost homologue of the mammalian hippocampus, we predicted that the spatial abilities required for females to locate and return accurately to nests of males may have produced a sex difference in the size of the telencephalic nuclei involved in spatial abilities, biased towards females. To test this hypothesis, we assessed the home ranges and measured the size of the dorsolateral telencephalon of both sexes during the breeding season in two blenniid species, the shanny (Lipophrys pholis) and the Azorean rock-pool blenny (Parablennius parvicornis). We chose these two species because they differ in the degree of chemical communication they use, and this could also lead to differences in telencephalic areas. As predicted, in both species females present considerably larger home ranges paralleled by larger dorsolateral ventral telencephalic nuclei (DLv) than males. Other telencephalic nuclei that were measured did not show any sex difference in size. These results suggest that the DLv is involved in spatial abilities in blenniid fish and that sexual selection may be promoting this divergence as already described for mammals and birds.
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Cell functional enviromics: unravelling the function of environmental factors.
BMC Syst Biol
PUBLISHED: 01-12-2011
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While functional genomics, focused on gene functions and gene-gene interactions, has become a very active field of research in molecular biology, equivalent methodologies embracing the environment and gene-environment interactions are relatively less developed. Understanding the function of environmental factors is, however, of paramount importance given the complex, interactive nature of environmental and genetic factors across multiple time scales.
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Stimulation of DNA repair in Saccharomyces cerevisiae by Ginkgo biloba leaf extract.
Food Chem. Toxicol.
PUBLISHED: 01-09-2011
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Many extracts prepared from plants traditionally used for medicinal applications contain a variety of phytochemicals with antioxidant and antigenotoxic activity. In this work we measured the DNA protective effect of extracts of Ginkgo biloba leaves from oxidative stress using Saccharomyces cerevisiae as experimental model. The extract improved viability of yeast cells under oxidative stress imposed by hydrogen peroxide. In accordance with previous reports on antioxidant properties of G. biloba extracts, pre-incubation of yeast cells promoted a decrease in intracellular oxidation. We assessed DNA damage by our recently developed yeast comet assay protocol. Upon oxidative shock, DNA damage decreased in a dose-dependent manner in experiments of pre-incubation and simultaneous incubation with the extract, indicating a direct protective effect. In addition, the extract improved DNA repair rate following oxidative shock as measured by faster disappearance of comet tails. This suggests that the extract stimulates the DNA repair machinery in its DNA protective action in addition to directly protect DNA from oxidation. The observed DNA repair depends on the DNA repair machinery since no DNA repair was observed under restrictive conditions in a conditional mutant of the CDC9 gene (Accession No. Z74212), encoding the DNA ligase involved in the final step of both nucleotide and base excision repair.
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Exploratory study assessing efficacy and complications of TVT-O, TVT-Secur, and Mini-Arc: results at 12-month follow-up.
Eur. Urol.
PUBLISHED: 01-08-2011
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Contemporary surgical treatment of female stress urinary incontinence (SUI) includes retropubic and transobturator (TO) midurethral slings (MUS). Case series of single-incision slings (SIS) have shown similar outcomes with lower morbidity.
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Kinetics of production and characterization of the fucose-containing exopolysaccharide from Enterobacter A47.
J. Biotechnol.
PUBLISHED: 12-17-2010
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A fucose-containing exopolysaccharide (EPS) was produced by the bacterium Enterobacter A47 using glycerol byproduct from the biodiesel industry. The analysis of kinetic data suggested a partially growth associated EPS synthesis model. Although the EPS was composed of fucose, galactose and glucose at all cultivation stages, their relative proportion has varied considerably during the run. At the beginning (24h), glucose was the main component (82.4 wt.%), being fucose and galactose minor components (5.0 wt.% and 10.9 wt.%, respectively), while at the end (96 h) it was composed of 26.0 wt.% fucose, 28.9 wt.% galactose and 43.7 wt.% glucose. The acyl groups content and composition have also changed, reaching their maximum content (19.2wt.%) at the end of the run. Moreover, the molecular weight has increased linearly during the run (from 8×10(5) to 5×10(6)). The changes observed in EPS composition and molecular weight have also had an impact upon the polymers intrinsic viscosity, as shown by its linear increase from 3.95 to 10.72 dL g(-1). The results suggest that the culture might have synthesized at least two distinct EPS, with different sugar composition and average molecular weight, which predominated at different cultivation stages.
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Hormonal mechanisms of cooperative behaviour.
Philos. Trans. R. Soc. Lond., B, Biol. Sci.
PUBLISHED: 08-04-2010
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Research on the diversity, evolution and stability of cooperative behaviour has generated a considerable body of work. As concepts simplify the real world, theoretical solutions are typically also simple. Real behaviour, in contrast, is often much more diverse. Such diversity, which is increasingly acknowledged to help in stabilizing cooperative outcomes, warrants detailed research about the proximate mechanisms underlying decision-making. Our aim here is to focus on the potential role of neuroendocrine mechanisms on the regulation of the expression of cooperative behaviour in vertebrates. We first provide a brief introduction into the neuroendocrine basis of social behaviour. We then evaluate how hormones may influence known cognitive modules that are involved in decision-making processes that may lead to cooperative behaviour. Based on this evaluation, we will discuss specific examples of how hormones may contribute to the variability of cooperative behaviour at three different levels: (i) within an individual; (ii) between individuals and (iii) between species. We hope that these ideas spur increased research on the behavioural endocrinology of cooperation.
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Measuring oxidative DNA damage and DNA repair using the yeast comet assay.
Yeast
PUBLISHED: 07-27-2010
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Chromosomal DNA damage can be a result of several processes and agents of endogenous or exogenous origin. These cause strand breaks or oxidized bases that lead to strand breaks, which relax the normally supercoiled genomic DNA and increase its electrophoretic mobility. The extent of DNA damage can be assessed by single cell gel electrophoresis, where the chromosomal DNA migration distance correlates with the extent of DNA damage. This technique has been used for a variety of applications with several organisms, but only a few studies have been reported for Saccharomyces cerevisiae. A possible reason for this absence is that low cellular DNA content could hamper visualization. Here we report an optimization of the comet assay protocol for yeast cells that is robust and sensitive enough to reproducibly detect background DNA damage and oxidative damage caused by hydrogen peroxide. DNA repair was observed and quantified as diminishing comet tail length with time after oxidative stress removal in a process well described by first-order kinetics with a tail length half-life of 11 min at 37 °C. This is, to our knowledge, the first quantitative measurement of DNA repair kinetics in S. cerevisiae by this method. We also show that diet antioxidants protect from DNA damage, as shown by a three-fold decrease in comet tail length. The possibility of assessment of DNA damage and repair in individual cells applied to the model organism S. cerevisiae creates new perspectives for studying genotoxicity and DNA repair.
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Does access to the bluestreak cleaner wrasse Labroides dimidiatus affect indicators of stress and health in resident reef fishes in the Red Sea?
Horm Behav
PUBLISHED: 07-25-2010
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Interactions between the bluestreak cleaner wrasse Labroides dimidiatus and its client reef fish are a textbook example of interspecific mutualism. The fact that clients actively visit cleaners and invite inspection, together with evidence that cleaners eat many client ectoparasites per day, indeed strongly suggests a mutualistic relationship. What remains unknown is how parasite removal affects the physiology of clients and thereby their body condition, health, and immune function. Here we addressed these issues in a field study in Ras Mohammed National Park, Egypt. In our study area, small reef patches are inter-spaced with areas of sandy substrate, thereby preventing many species (i.e., residents, including cleaner wrasses) from travelling between the reef patches. This habitat structure leads to a mosaic of resident clients with and without access to bluestreak cleaner wrasses, further referred to as "cleaner access", on which we focused our study. We found that residents with cleaner access had higher body condition than residents without cleaner access. However, indicators of stress like variation in cortisol levels corrected for handling time and various immune parameters were apparently unaffected by cleaner access. In fact antibody responses were significantly higher in fishes without cleaner access. This suggests that cleaner access decreases the need for active immunity and that this releases resources that might be allocated to other functions such as somatic growth and reproduction.
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High-throughput analysis of animal cell cultures using two-dimensional fluorometry.
J. Biotechnol.
PUBLISHED: 07-14-2010
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We report a new method which combines fluorescence spectroscopy at microtiter plate scale with multivariate statistical analysis for rapid and high-throughput analysis of secreted recombinant protein and viable cell growth in animal cell cultures. The potential of the method is demonstrated by application to cultures of three Chinese Hamster Ovary (CHO) cell clones with distinct IgG(4) antibody yields. Supernatant samples collected throughout culture time were analysed by two-dimensional fluorometry; significant changes were observed in the regions of tryptophan, metabolic cofactors and vitamins. Partial least squares regression was then used to correlate the entire fluorescence map with measured concentrations of antibody and viable cells. For both target variables, a model was calibrated with representative data from the two less productive clones and validated with data from the best producer clone; this allowed viable cell density to be predicted for the validation clone with an average error of 10%; even better, the secreted antibody could be predicted with an average error of 7%, proving the predictive capacity of the model beyond the calibration region. All the main spectral regions were required to establish the best correlations for both targeted variables. In conclusion, this method effectively analyzes cellular productivity in 96-well plate format, shortening the time spent in early phases of bioprocess development.
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Social environment affects testosterone level in captive male blue-black grassquits.
Horm Behav
PUBLISHED: 06-13-2010
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The challenge hypothesis proposes that testosterone (T) elevation above what is needed for breeding is associated with social factors, and males possibly modulate their hormonal response to variations in population density and sex ratio. We investigated the role of social environment in altering testosterone levels and aggression in a tropical, seasonally breeding grassquit (Volatinia jacarina). We exposed males to three social conditions during 1 year: all-males treatment (six males), mixed treatment (three males-three females), and paired treatment (one male-one female). We quantified aggressiveness among males and T plasma concentration for each individual in each treatment monthly. We found that more aggressive interactions occurred in the all-males treatment than in the mixed treatment. The data also revealed that, coincident with these behavioral changes, the patterns of T variation through time in each treatment were markedly different. The all-males treatment exhibited an early increase in T concentration, which was sustained for a lengthy period with two distinctive peaks, and subsequently declined sharply. The mixed treatment presented an intermediate pattern, with more gradual increase and decrease in T levels. At the other extreme, the paired treatment presented a later rise in T concentration. We conclude that the more competitive environment, with higher density of males, caused the early and higher elevation in T level, thus the presence of competitors may influence the decision of how much a male should invest in reproduction. We suggest that the males perception of his social environment ultimately mediates hormonal production and alters his reproductive strategy.
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The Saccharomyces cerevisiae Genes, AIM45, YGR207c/CIR1 and YOR356w/CIR2, Are Involved in Cellular Redox State Under Stress Conditions.
Open Microbiol J
PUBLISHED: 06-02-2010
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Mammalian electron transfer flavoproteins comprise a mitochondrial matrix heterodimer, and an electron transfer flavoprotein dehydrogenase localized in the mitochondrial inner membrane. Electrons from primary acyl-CoA dehydrogenases, of mitochondrial metabolism of fatty acids and amino acids, are transferred to the matricial heterodimer and, subsequently, to the electron transfer flavoprotein dehydrogenase, which transfers electrons to ubiquinone of the mitochondrial electron transport chain. Several evidences suggest that these proteins may convey electrons directly to molecular oxygen, yielding reactive oxygen species. In this work, we investigated phenotypes of the yeast mutants affected in the orthologous genes of the matrix heterodimer (AIM45 and YGR207c/CIR1) and of the electron transfer flavoprotein dehydrogenase (YOR356w/CIR2). The mutant strains aim45 and yor356w/cir2 displayed better growth on several non-fermentable carbon sources, which depended on the component of the electron transport chain that accepts the electrons resulting from its mitochondrial oxidation. Furthermore, upon heat shock, the mutant strains presented decreased intracellular oxidation, suggesting that these flavoproteins are a source of reactive oxygen species. Other phenotypes identified suggest that AIM45, YGR207c/CIR1 and YOR356w/CIR2 can protect cells from oxidative and heat stress, which encompass increased heat stress sensitivity, superoxide sensitivity, both only on non-fermentable carbon sources.
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Modelling biochemical networks with intrinsic time delays: a hybrid semi-parametric approach.
BMC Syst Biol
PUBLISHED: 05-12-2010
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This paper presents a method for modelling dynamical biochemical networks with intrinsic time delays. Since the fundamental mechanisms leading to such delays are many times unknown, non conventional modelling approaches become necessary. Herein, a hybrid semi-parametric identification methodology is proposed in which discrete time series are incorporated into fundamental material balance models. This integration results in hybrid delay differential equations which can be applied to identify unknown cellular dynamics.
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Ectomycorrhizal fungi as an alternative to the use of chemical fertilisers in nursery production of Pinus pinaster.
J. Environ. Manage.
PUBLISHED: 03-25-2010
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Addition of fertilisers is a common practice in nursery production of conifer seedlings. The aim of this study was to evaluate whether ectomycorrhizal (ECM) fungi can be an alternative to the use of chemical fertilisers in the nursery production of Pinus pinaster. A greenhouse nursery experiment was conducted by inoculating seedlings obtained from seeds of P. pinaster plus trees with a range of compatible ECM fungi: (1) Thelephora terrestris, (2) Rhizopogon vulgaris, (3) a mixture of Pisolithus tinctorius and Scleroderma citrinum, and (4) a mixture of Suillus bovinus, Laccaria laccata and Lactarius deterrimus, using forest soil as substrate. Plant development was assessed at two levels of N-P-K fertiliser (0 or 600 mg/seedling). Inoculation with a mixture of mycelium from S. bovinus, L. laccata and L. deterrimus and with a mixture of spores of P. tinctorius and S. citrinum improved plant growth and nutrition, without the need of fertiliser. Results indicate that selected ECM fungi can be a beneficial biotechnological tool in nursery production of P. pinaster.
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A preformulation study of a new medicine for Chagas disease treatment: physicochemical characterization, thermal stability, and compatibility of benznidazole.
AAPS PharmSciTech
PUBLISHED: 02-15-2010
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This work aimed the studies of physicochemical characterization, thermal stability, and compatibility of benznidazole (BNZ) drug by spectroscopy (NMR, IR), thermoanalytical (differential thermal analysis, differential scanning calorimetry, and thermogravimetry), and chromatographic (HPLC) techniques, beyond the analytical tools of Vant Hoff equation and Ozawa model. The compatibility study was conducted by binary mixtures (1:1, w/w) of the drug with microcrystalline cellulose 102 and 250, anhydrous lactose, and sodium starch glycolate. The physicochemical characterization confirmed data reported in scientific literature, guaranteeing authenticity of the analyzed raw material. The drug melts at 191.68°C (?H, 119.71 J g(-1)), characteristic of a non-polymorphic raw material, and a main stage decomposition at 233.76-319.35°C (?m, 43.32%) occurred, ending the study with almost all mass volatilized. The quantification of drug purity demonstrated a correlation of 99.63% between the data obtained by chromatographic (99.20%) and thermoanalytical technique (99.56%). The Arrhenius equation and Ozawa model showed a zero-order kinetic behavior for the drug decomposition, and a calculated provisional validity time was 2.37 years at 25°C. The compatibility study evidenced two possible chemical incompatibilities between BNZ and the tested excipients, both associated by the authors to the reaction of the BNZs amine and a polymer carbohydrates carbonile, being maillard reactions. The BNZ reaction with anhydrous lactose is more pronounced than with the sodium starch glycolate because the lactose has more free hydroxyl groups to undergo reduction by the drug. In this sense, this work guides the development of a new solid pharmaceutical product for Chagas disease treatment, with defined quality control parameters and physicochemical stability.
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Antioxidant capacity of Macaronesian traditional medicinal plants.
Molecules
PUBLISHED: 02-09-2010
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The use of many traditional medicinal plants is often hampered by the absence of a proper biochemical characterization, essential to identify the bioactive compounds present. The leaves from five species endemic to the Macaronesian islands with recognized ethnobotanical applications were analysed: Apollonias barbujana (Cav.) Bornm., Ocotea foetens (Ainton) Baill, Prunus azorica (Mouill.) Rivas-Mart., Lousã, Fern. Prieto, E. Días, J.C. Costa & C. Aguiar, Rumex maderensis Lowe and Plantago arborescens Poir. subsp. maderensis (Dcne.) A. Hans. et Kunk.. Since oxidative stress is a common feature of most diseases traditionally treated by these plants, it is important to assess their antioxidant capacity and determine the molecules responsible for this capacity. In this study, the antioxidant capacity of these plants against two of the most important reactive species in human body (hydroxyl and peroxyl radicals) was determined. To trace the antioxidant origin total phenol and flavonoid contents as well as the polyphenolic profile and the amount of trace elements were determined. There was a wide variation among the species analysed in what concerns their total leaf phenol and flavonoid contents. From the High Performance Liquid Chromatography (HPLC) electrochemically detected peaks it was possible to attribute to flavonoids the antioxidant capacity detected in A. barbujana, O. foetens, R. maderensis and P. azorica extracts. These potential reactive flavonoids were identified for A. barbujana, R. maderensis and P. azorica. For R. maderensis a high content (7 mg g-1 dry weight) of L-ascorbic acid, an already described antioxidant phytomolecule, was found. A high content in selenomethionine (414.35 microg g-1 dry weight) was obtained for P. arborescens subsp. maderensis extract. This selenocompound is already described as a hydroxyl radical scavenger is reported in this work as also possessing peroxyl radical scavenging capacity. This work is a good illustration of different phytomolecules (flavonoids, organic acids and selenocompounds), presents in leaves of the five traditional medicinal plants endemic to Macaronesia, all exhibiting antioxidant properties.
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The role of predictability in the stress response of a cichlid fish.
Physiol. Behav.
PUBLISHED: 01-28-2010
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In recent years there has been an increasing interest in the cognitive abilities of fish with implications for animal welfare and management of rearing operations. Although it is known that psychological factors can modulate the stress response in mammals, this aspect has seldom been investigated within stress in fish. In this study we investigate whether the perception (appraisal) that fish make of significant environmental events modifies their behavioural and physiological response. For this purpose we have used a predictable vs. unpredictable paradigm for positive (feeding) and negative (confinement) events using the cichlid fish Oreochromis mossambicus as a model species. Results show that there is a differential effect of predictability for the feeding and confinement events. In the confinement experiment, predictability involved more attention to the visual cue and lower cortisol. The feeding event triggered higher levels of anticipatory behaviour and a tendency for higher cortisol in the predictable group. Therefore, predictable negative events reduce the cortisol response. Predictable positive events may elicit an anticipatory response, and when there is a significant delay between the visual cue and the actual occurrence of the event, it may also contain elements that can be interpreted as a stress response. These findings demonstrate that fish can appraise relevant aspects of the environment, with welfare implications for housing, husbandry and experimental procedures.
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Validation of a method for determination of ampicillin in human plasma using LC-DAD.
J Chromatogr Sci
PUBLISHED: 10-20-2009
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We describe the validation data of a simple but selective chromatographic method for determination of ampicillin in human plasma using liquid chromatography-diode array detector. Blank plasma free of drugs was transferred to eppendorfs tubes and spiked with ampicillin stock solution to obtain quality control samples at 1.00, 2.50, 5.00, and 10.00 microg/mL. Extraction of ampicillin and cephalexin (internal standard) from plasma samples (250 microL) was investigated using three different methods: precipitation with perchloric acid, ultra-filtration and solid-phase extraction. Chromatographic separation was achieved using a Shimpak C(18) column (300 mm x 4.6 mm i.d.; 5 microm), and detection was done at 215 nm with a diode array UV-Vis detector. The mobile phase consisted of dihydrogen phosphate (pH 3.5)-acetonitrile (87.5:12.5, v/v) delivered at a flow rate of 1.00 mL/min. Selectivity was evaluated with different pools of human plasma. Perchloric acid precipitation showed an excellent selectivity for normal plasma. The precipitation method presented recoveries above 84.0 +/- 3.3% and 82.0 +/- 1.6%, (n = 3) for ampicillin and cephalexin, respectively. The method has a limit of detection of 0.15 microg/mL and is linear in the range of 0.30 to 100.00 microg/mL. Standardized residue analysis demonstrated normality and homocedasticity. Inter-day precision was 4.5%, and accuracy was 11.1% (n = 9). Stability studies demonstrated instability of b-lactamics in human plasma at 20 and 2 degrees C after 6 and 360 h of storage, respectively.
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Hormonal anticipation of territorial challenges in cichlid fish.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 09-01-2009
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In many territorial species androgens respond to social interactions. This response has been interpreted as a mechanism for adjusting aggressive motivation to a changing social environment. Therefore, it would be adaptive to anticipate social challenges and reacting to their clues with an anticipatory androgen response to adjust agonistic motivation to an imminent social challenge. Here we test the hypothesis of an anticipatory androgen response to territorial intrusions using classical conditioning to establish an association between a conditioned stimulus (CS = light) and an unconditioned stimulus (US = intruder male) in male cichlid fish (Oreochromis mossambicus). During the training phase conditioned males (CS-US paired presentations) showed a higher decrease in latency for agonistic response toward the intruder than unconditioned males (CS-US unpaired presentations). In the test trial, conditioned males showed an increase in androgen levels (i.e., testosterone and 11-ketotestosterone) relative to baseline, in response to the CS alone. This increase was similar to that of control males exposed to real intruders after CS, whereas unconditioned males showed a decrease in androgen levels in response to the CS. Furthermore, conditioned males were significantly more aggressive than unconditioned males during the post-CS period on test trial, even though the intruder male was not present during this period. These results reveal the occurrence of a conditioned androgen response that may give territorial males an advantage in mounting a defense to upcoming territorial intrusions, if the ability to readily elevate androgens does not co-vary with other traits that bear costs.
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Social behavior in context: Hormonal modulation of behavioral plasticity and social competence.
Integr. Comp. Biol.
PUBLISHED: 07-21-2009
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In social species animals should fine-tune the expression of their social behavior to social environments in order to avoid the costs of engaging in costly social interactions. Therefore, social competence, defined as the ability of an animal to optimize the expression of its social behavior as a function of the available social information, should be considered as a performance trait that impacts on the Darwinian fitness of the animal. Social competence is based on behavioral plasticity which, in turn, can be achieved by different neural mechanisms of plasticity, namely by rewiring or by biochemically switching nodes of a putative neural network underlying social behavior. Since steroid hormones respond to social interactions and have receptors extensively expressed in the social behavioral neural network, it is proposed that steroids play a key role in the hormonal modulation of social plasticity. Here, we propose a reciprocal model for the action of androgens on short-term behavioral plasticity and review a set of studies conducted in our laboratory using an African cichlid fish (Oreochromis mossambicus) that provide support for it. Androgens are shown to be implicated as physiological mediators in a wide range of social phenomena that promote social competence, namely by adjusting the behavioral response to the nature of the intruder and the presence of third parties (dear enemy and audience effects), by anticipating territorial intrusions (bystander effect and conditioning of the territorial response), and by modifying future behavior according to prior experience of winning (winner effect). The rapid behavioral actions of socially induced short-term transient changes in androgens indicate that these effects are most likely mediated by nongenomic mechanisms. The fact that the modulation of rapid changes in behavior is open to the influence of circulating levels of androgens, and is not exclusively achieved by changes in central neuromodulators, suggests functional relevance of integrating body parameters in the behavioral response. Thus, the traditional view of seeing neural circuits as unique causal agents of behavior should be updated to a brain-body-environment perspective, in which these neural circuits are embodied and the behavioral performance (and outcomes as fitness) depends on a dynamic relationship between the different levels. In this view hormones play a major role as behavioral modulators.
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Acute myocardial infarction after thrombolytic treatment of acute ischemic stroke.
Rev Port Cardiol
PUBLISHED: 06-25-2009
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Thrombolytic treatment in patients with acute ischemic stroke improves their clinical prognosis when administered within three hours of symptom onset. We report the case of a 57-year-old patient with a history of paroxysmal atrial fibrillation and hypertension who developed an anterior acute myocardial infarction after systemic thrombolytic treatment for acute ischemic stroke. Embolization of a pre-existing cardiac thrombus or in situ formation of a thrombus in a coronary artery has to be considered as a potential adverse effect of thrombolytic therapy in stroke patients.
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Brain aromatase mRNA expression in two populations of the peacock blenny Salaria pavo with divergent mating systems.
Horm Behav
PUBLISHED: 05-25-2009
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Aromatase, the key enzyme in the conversion of androgens to estrogens, regulates the availability of these hormones in tissues and controls many physiological and behavioral processes. In fish and other vertebrates, the regulation of aromatase expression in the brain has been implicated in the modulation of male sexual and aggressive behaviors. Here, the pattern of mRNA expression of the brain aromatase isoform (encoded by the CYP19A2 gene also referred as CYP19b) was quantified at the peak of spawning season in brain macroareas from males and females of the blenny Salaria pavo originated from two populations displaying male alternative reproductive tactics but differing in their mating systems. In Trieste (Adriatic) nesting males aggressively defend nests and take the initiative in courtship and perform sexual displays more often than females while in Ria Formosa (Southern Portugal) the pattern is reversed as a result of shortage of appropriate nesting sites. Nesting males from Ria Formosa had overall higher levels of brain aromatase mRNA expression than nesting males from Trieste, suggesting a higher brain estrogen synthesis in these males. Since in some fish species exogenous estradiol administration has been shown to decrease sexual and agonistic behaviors, the higher levels of brain aromatase in Ria Formosa nesting males may explain their reduced expression of sexual and aggressive displays when compared with nesting males from Trieste. Alternatively, the higher brain aromatase levels in nesting males from Ria Formosa could be a mechanism to decrease the putative androgen-induced activation of aggressive and sexual displays by reducing the local availability of androgens through their metabolization into estrogens. Although females and parasitic female-like males also differ in their displays between populations, the interpopulational pattern of brain aromatase mRNA expression was similar, suggesting that other neuroendocrine agents mediate the expression of female and female-like behaviors. In conclusion, brain aromatase availability seems like a probable mechanism to regulate the effects of steroids on the brain circuits underlying the expression of sexual and agonistic displays in S. pavo.
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Improving baculovirus production at high cell density through manipulation of energy metabolism.
Metab. Eng.
PUBLISHED: 05-12-2009
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The insect cells/baculovirus system is well recognized as a safe and suitable technology to produce heterologous proteins, vaccines and vectors for gene therapy. Efficient and robust production processes, able to deliver higher product concentrations, are however still needed to cope with increased requirements for large-scale manufacture. The work herein presented describes a combined experimental and modelling effort to quantify and environmentally manipulate the metabolism of Spodoptera frugiperda cells, targeting high cell density production of baculovirus vectors with potential application in human gene therapy. Culture medium supplementation with pyruvate or alpha-ketoglutarate at the time of infection resulted in 6-7-fold higher specific baculovirus yields at high cell density when compared to control cultures. This pushed volumetric titers to levels higher than classical low cell density infections. A quantitative description of intracellular pathways is provided using metabolic flux analysis; a direct stimulation of carbon flow through the tricarboxylic acids cycle was observed. Analysis of flux partitioning coefficients at the pyruvate and alpha-ketoglutarate branch-points further revealed a metabolic transition to a more energetically active state, which was confirmed by increased intracellular adenosine triphosphate generation rates. These results represent a cost-efficient and scalable strategy for high cell density production of recombinant baculovirus vectors.
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Intraprostatic Botulinum Toxin Type A injection in patients with benign prostatic enlargement: duration of the effect of a single treatment.
BMC Urol
PUBLISHED: 04-30-2009
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Botulinum Toxin Type-A (BoNT/A) intraprostatic injection can induce prostatic involution and improve LUTS and urinary flow in patients with Benign Prostatic Enlargement (BPE). However, the duration of these effects is unknown. The objective of this work was to determine the duration of prostate volume reduction after one single intraprostatic injection of 200U of Botulinum Toxin Type-A.
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Environmental modulation of androgen levels and secondary sex characters in two populations of the peacock blenny Salaria pavo.
Horm Behav
PUBLISHED: 04-22-2009
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Morphology and endocrinology were studied in two populations of the peacock blenny Salaria pavo, with different regimes of sexual selection imposed by differences in nest site availability. The peacock blenny is a small, sexually dimorphic benthic fish that presents exclusive paternal care of the clutch and inhabits rocky shores of the Mediterranean and adjacent Atlantic areas. In a population from the Gulf of Trieste (Northern Adriatic sea) inhabiting rocky shores where nest sites are abundant, male-male competition for nests is low, males court females and a low frequency of alternative reproductive tactics (small, parasitic female-mimicking sneaker males that change tactic into nest holders in subsequent breeding seasons) occurs. Conversely at Ria Formosa, a coastal lagoon in Southern Portugal, where nest sites are scarce and highly aggregated, male-male competition for nests is very high, there is sex-role reversal with female courtship and a high frequency of alternative reproductive tactics is observed. Concomitantly, at Ria Formosa nest holder males are larger and present more developed secondary sex characters and higher levels of 11KT than at the Gulf of Trieste. However, the gonads of nest holders and parasitic males were larger in the Gulf of Trieste population. Competition for nests at Ria Formosa seems to promote more developed secondary sex characters in nest site scarcity conditions, while competition for females at the Gulf of Trieste seems to be spurring sperm competition among males in populations where nest sites are more abundant. 11KT was thus associated with the development and expression of secondary sex characters in contrasting environments. These results exemplify how the modulation of behavioral plasticity and secondary sex characters by the social environment can be mediated by androgens.
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On-line adaptive metabolic flux analysis: Application to PHB production by mixed microbial cultures.
Biotechnol. Prog.
PUBLISHED: 04-09-2009
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In this work, an algorithm for on-line adaptive metabolic flux analysis (MFA) is proposed and applied to polyhydroxybutyrate (PHB) production by mixed microbial cultures (MMC). In this process, population dynamics constitutes an important source of perturbation to MFA calculations because some stoichiometric and energetic parameters of the underlying metabolic network are continuously changing over time. The proposed algorithm is based on the application of the observer-based estimator (OBE) to the central MFA equation, whereby the role of the OBE is to force the accumulation of intracellular metabolites to converge to zero by adjusting the values of unknown network parameters. The algorithm was implemented in a reactor equipped with on-line analyses of dissolved oxygen and carbon dioxide through respirometric and titrimetric measurements. The oxygen and carbon dioxide fluxes were measured directly, whereas acetate, PHB, and sludge production fluxes were estimated indirectly using a projection of latent structures model calibrated a priori with off-line measurements. The algorithm was implemented in a way that the network parameters associated with biosynthesis were adjusted on-line. The algorithm proofed to converge exponentially with the steady state error always below 1 mmol/L. The estimated fluxes passed the consistency index test for experimental error variances as low as 1%. The comparison of measured and estimated respiratory coefficient and of the theoretical and estimated yield of sludge on acetate further confirmed the metabolic consistency of the parameters that were estimated on-line.
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Characterization of an extracellular polysaccharide produced by a Pseudomonas strain grown on glycerol.
Bioresour. Technol.
PUBLISHED: 03-31-2009
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A new extracellular charged polysaccharide composed mainly by galactose, with lower amounts of mannose, glucose and rhamnose, was produced by the cultivation of Pseudomonas oleovorans NRRL B-14682 using glycerol as the sole carbon source. Thermal and solid-state NMR analysis showed that this polymer is essentially amorphous, with a glass transition temperature of 155.7 degrees C. The exopolysaccharide aqueous solutions have viscoelastic properties similar to that of Guar gum, but with affinity to salts as a result of its polyelectrolyte character. In addition, the exopolysaccharide has demonstrated good flocculating and emulsifying properties and film-forming capacity. These properties make this polymer a good alternative to more expensive natural polysaccharides, such as Guar gum, in several applications in the food, pharmaceutical, cosmetic, textile, paper and petroleum industries.
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