Studies on blood protein and enzyme polymorphisms in the european moose (Alces Alces)

International audienc

Latitudinal clines in gene expression and cis-regulatory element variation in Drosophila melanogaster

Abstract Background Organisms can rapidly adapt to their environment when colonizing a new habitat, and this could occur by changing protein sequences or by altering patterns of gene expression. The importance of gene expression in driving local adaptation is increasingly being appreciated, and cis-regulatory elements (CREs), which control and modify the expression of the nearby genes, are predicted to play an important role. Here we investigate genetic variation in gene expression in immune-challenged Drosophila melanogaster from temperate and tropical or sub-tropical populations in Australia and United States. Results We find parallel latitudinal changes in gene expression, with genes involved in immunity, insecticide resistance, reproduction, and the response to the environment being especially likely to differ between latitudes. By measuring allele-specific gene expression (ASE), we show that cis-regulatory variation also shows parallel latitudinal differences between the two continents and contributes to the latitudinal differences in gene expression. Conclusions Both Australia and United States were relatively recently colonized by D. melanogaster, and it was recently shown that introductions of both African and European flies occurred, with African genotypes contributing disproportionately to tropical populations. Therefore, both the demographic history of the populations and local adaptation may be causing the patterns that we see

Optimal Best-Arm Identification Methods for Tail-Risk Measures

Conditional value-at-risk (CVaR) and value-at-risk (VaR) are popular tail-risk measures in finance and insurance industries as well as in highly reliable, safety-critical uncertain environments where often the underlying probability distributions are heavy-tailed. We use the multi-armed bandit best-arm identification framework and consider the problem of identifying the arm from amongst finitely many that has the smallest CVaR, VaR, or weighted sum of CVaR and mean. The latter captures the risk-return trade-off common in finance. Our main contribution is an optimal $\delta$-correct algorithm that acts on general arms, including heavy-tailed distributions, and matches the lower bound on the expected number of samples needed, asymptotically (as $\delta$ approaches $0$). The algorithm requires solving a non-convex optimization problem in the space of probability measures, that requires delicate analysis. En-route, we develop new non-asymptotic empirical likelihood-based concentration inequalities for tail-risk measures which are tighter than those for popular truncation-based empirical estimators.Comment: 55 pages, 4 figure

NASAL COLONIZATION OF METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS AMONG CLINICAL POSTGRADUATES IN A COASTAL KARNATAKA MEDICAL COLLEGE - PREVALENCE AND ANTIBIOGRAM PATTERN

Objective: The incidence of community-acquired and hospital-acquired Staphylococcus aureus infections has been rising with increasing emergence of drug-resistant strains called methicillin-resistant S. aureus (MRSA). The prime objective of the study was to ascertain the prevalence of carriage rate of MRSA among the clinical postgraduate students of a medical college of Coastal Karnataka, India.Methods: A total of 133 clinical postgraduates have participated in the present study. Swabs from both anterior nares were collected and processed for S. aureus from the consenting participants after giving a set of questionnaires. The isolated strains of S. aureus were screened for methicillin resistance by the modified Kirby-Bauer method using cefoxitin (30 μg) disc. Antibiotic susceptibility testing for all isolates of S. aureus was also done against other antibiotics. E test was used to know vancomycin resistance for MRSA.Results: The numbers of S. aureus isolated of 133 participants were 22 (16.5%). Of 22 isolates of S. aureus, 12 were MRSA (54.5%). The MRSA carriage rate of clinical postgraduates of a medical college from Coastal Karnataka, India, was 9%. All the MRSA isolates were susceptible to vancomycin and teicoplanin. Contact with chronic patients and consumption of antibiotics in past 6 months were found to be statistically significant as the risk factor associated with the acquisition of S. aureus/MRSA carriage status among the participants. No vancomycin-resistant S. aureus was reported from the present study.Conclusion: The S. aureus and MRSA nasal carriage rates of clinical postgraduates recorded in this study were significantly high when compared with the general population. This could be due to their continuous exposure to patients in clinical settings. It is desirable that these students must receive sufficient knowledge regarding control measures to avoid the spread of MRSA infection in hospitals

Effect of grape seed extract on heat resistance of Clostridium perfringens vegetative cells in sous vide processed ground beef

PMID = 3100024

A dissipative random velocity field for fully developed fluid turbulence

We investigate the statistical properties, based on numerical simulations and analytical calculations, of a recently proposed stochastic model for the velocity field of an incompressible, homogeneous, isotropic and fully developed turbulent flow. A key step in the construction of this model is the introduction of some aspects of the vorticity stretching mechanism that governs the dynamics of fluid particles along their trajectory. An additional further phenomenological step aimed at including the long range correlated nature of turbulence makes this model depending on a single free parameter $\gamma$ that can be estimated from experimental measurements. We confirm the realism of the model regarding the geometry of the velocity gradient tensor, the power-law behaviour of the moments of velocity increments (i.e. the structure functions), including the intermittent corrections, and the existence of energy transfers across scales. We quantify the dependence of these basic properties of turbulent flows on the free parameter $\gamma$ and derive analytically the spectrum of exponents of the structure functions in a simplified non dissipative case. A perturbative expansion in power of $\gamma$ shows that energy transfers, at leading order, indeed take place, justifying the dissipative nature of this random field.Comment: 38 pages, 5 figure

Vector competence of Aedes aegypti mosquitoes for filarial nematodes is affected by age and nutrient limitation

Mosquitoes are one of the most important vectors of human disease. The ability of mosquitoes to transmit disease is dependent on the age structure of the population, as mosquitoes must survive long enough for the parasites to complete their development and infect another human. Age could have additional effects due to mortality rates and vector competence changing as mosquitoes senesce, but these are comparatively poorly understood. We have investigated these factors using the mosquito Aedes aegypti and the filarial nematode Brugia malayi. Rather than observing any effects of immune senescence, we found that older mosquitoes were more resistant, but this only occurred if they had previously been maintained on a nutrient-poor diet of fructose. Constant blood feeding reversed this decline in vector competence, meaning that the number of parasites remained relatively unchanged as mosquitoes aged. Old females that had been maintained on fructose also experienced a sharp spike in mortality after an infected blood meal ("refeeding syndrome") and few survived long enough for the parasite to develop. Again, this effect was prevented by frequent blood meals. Our results indicate that old mosquitoes may be inefficient vectors due to low vector competence and high mortality, but that frequent blood meals can prevent these effects of age