Effects of altitude on circadian rhythm of adult locomotor activity in Himalayan strains of Drosophila helvetica

Background  

We recently reported that the altitude of origin altered the photic and thermal sensitivity of the circadian pacemaker controlling eclosion and oviposition rhythms of high altitude Himalayan strains of Drosophila ananassae. The present study was aimed at investigating the effects of altitude of origin on the pacemaker controlling the adult locomotor activity rhythm of D. helvetica.     

Stability via asynchrony in Drosophila metapopulations with low migration rates

Very few experimental studies have examined how migration rate affects metapopulation dynamics and stability. We studied the dynamics of replicate laboratory metapopulations of Drosophila under different migration rates. Low migration stabilized metapopulation dynamics, while promoting unstable subpopulation dynamics, by inducing asynchrony among neighboring subpopulations. High migration synchronized subpopulation dynamics, thereby destabilizing the metapopulations. Contrary to some theoretical predictions, increased migration did not affect average population size. Simulations based on a simple non-species-specific population growth model captured most features of the data, which suggests that our results are generalizable.     

Interspecific hybridization between Brassica carinata and Brassica rapa

The crossability between Brassica carinata (BBCC, 2n=34) and Brassica rapa (AA, 2n=20), and the cytomorphology of their F₁ hybrids were studied. Hybrids between these two species were only obtained when B. carinata was used as the female parent. The hybrid plants exhibited intermediate leaf and flower morphology, and were found to be free from white rust and Alternaria blight diseases. One of the four F₁ plants was completely male sterile, while the remaining plants had 4.8, 8.6, and 10.9% stainable pollen, respectively. No seed was produced on hybrid plants under self pollination or in backcrosses; but seed was obtained from open pollination. The occurrence of the maximum of 11 bivalents as well as up to 44.8%) of cells with multivalent associations in the form of trivalents (0‐2) and a quadrivalent (0‐1) in the trigenomic triploid hybrid (ABC, 2n = 27) revealed intergenomic homoeology among the A, B and C genomes. Meiotic analysis of F₁ hybrids indicated that traits of economic importance, such as disease resistance, could be transferred from B. carinata to B. rapa through interspecific crosses.     

An Emissions Inventory for Regional Atmospheric Modeling of Mercury

Estimates of mercury emissions from individual sources and source categories are needed to understand relationships between the emissions and resulting deposition and to evaluate possible approaches to reducing those emissions. We have developed geographically-resolved estimates of annual average mercury emission rates from current anthropogenic sources in the 48 contiguous United States. These estimates were made by applying emission factors to individual facility operating data and to county-wide source activity levels. We apportioned the emissions to an Eulerian modeling grid system using point source coordinates and the fractions of county areas in each grid cell. Point sources account for about 89% of the 48-state total mercury emissions of 146.4 Mg/yr. Most of the emissions in the inventory are from combustion of mercury-containing fossil fuels and municipal waste, located primarily in the mid-Atlantic and Great Lakes states as well as in the Southeast. The major uncertainties in the emission estimates are caused by uncertainties in the emission factors used to develop the estimates. This uncertainty is likely a result of variability in the mercury content of the combusted materials and in the removal of mercury by air pollution control devices. The greatest research need to reduce uncertainties in mercury emission estimates is additional measurements to improve emission factors.     

Identification and characterization of SSRs in <Emphasis Type="Italic">Clarias batrachus</Emphasis> and their application in population study

Magur Clarias batrachus is an indigenous catfish, commonly found in India, Nepal, Bhutan and Bangladesh. Presently, the populations of magur have declined rapidly in their natural habitat mainly due to overexploitation and habitat degradation. Understanding the population genetic structure of the species has significance in improvement of stocks and in conservation of the species. In the present study, simple sequence repeat (SSR) markers were used to differentiate the populations of magur, collected from three geographic locations. For this, a total of 31,814 SSRs were mined from the de novo assembled pooled of whole genome sequence data of C. batrachus. A bioinformatics pipeline with stringent criteria was applied to analyze the data which resulted in selection of 30,142 microsatellite loci falling in the intergenic region. Out of the 25 loci selected for primer development, 16 loci were successfully amplified and 9 loci were found to be polymorphic in this species. The average observed as well as expected heterozygosity in the loci across different stocks varied from 0.652 to 0.688 and 0.864 to 0.873, respectively. These three populations were further segregated into two clusters based on the NJ genetic distance. The Lucknow population formed one cluster, while the Bhubaneswar and Kolkata populations constituted another cluster. A comparable finding was also deduced from the STRUCTURE analyses. The results revealed significant variation among the populations of C. batrachus under study.     

Himalayan Fish Manifest Higher Potential of Quality Nutrients for Human Health

Five species of snow trout (Schizothorax spp.) were investigated for their inherent nutritional value. Proximate composition, total fat, total cholesterol, triglyceride, fatty acids (FAs) profile, and mineral profiles were analyzed. Protein percentage in all five fish was found to be the same (P > 0.05), ranging from 15% to 18%. Moisture (75–82%) and lipid (1.5–8%) values were found to differ prominently (P < 0.05) in an inverse manner. Total fat (%), total cholesterol (mg/100 g), and triglyceride (mg/100 g) contents were found in the range of 2.73–6.54, 21.31–25.76, and 298.89–342.22, respectively. The trend of FAs in decreasing order was saturated > mono-unsaturated > polyunsaturated (n–6 > n–3). The sum of n–6 FAs value was higher than that of n–3, and the major n–6 and n–3 long chain polyunsaturated FAs (PUFAs) were arachidonic acid and docosahexaenoic acid, respectively. In most of these fish, the profile of macrominerals was phosphorus > potassium > calcium > sodium > magnesium, while the trend for microminerals was iron > zinc > copper > manganese. The snow trout species with best contribution potential to the daily requirement of n–3 long chain PUFAs was found in S. esocinus and S. niger, calcium and phosphorus in S. plagiostomus, and iron and copper in S. progastus.