Prioritizing Tiger Conservation through Landscape Genetics and Habitat Linkages

Even with global support for tiger (Panthera tigris) conservation their survival is threatened by poaching, habitat loss and isolation. Currently about 3,000 wild tigers persist in small fragmented populations within seven percent of their historic range. Identifying and securing habitat linkages that connect source populations for maintaining landscape-level gene flow is an important long-term conservation strategy for endangered carnivores. However, habitat corridors that link regional tiger populations are often lost to development projects due to lack of objective evidence on their importance. Here, we use individual based genetic analysis in combination with landscape permeability models to identify and prioritize movement corridors across seven tiger populations within the Central Indian Landscape. By using a panel of 11 microsatellites we identified 169 individual tigers from 587 scat and 17 tissue samples. We detected four genetic clusters within Central India with limited gene flow among three of them. Bayesian and likelihood analyses identified 17 tigers as having recent immigrant ancestry. Spatially explicit tiger occupancy obtained from extensive landscape-scale surveys across 76,913 km² of forest habitat was found to be only 21,290 km². After accounting for detection bias, the covariates that best explained tiger occupancy were large, remote, dense forest patches; large ungulate abundance, and low human footprint. We used tiger occupancy probability to parameterize habitat permeability for modeling habitat linkages using least-cost and circuit theory pathway analyses. Pairwise genetic differences (F _ST) between populations were better explained by modeled linkage costs (r>0.5, p<0.05) compared to Euclidean distances, which was in consonance with observed habitat fragmentation. The results of our study highlight that many corridors may still be functional as there is evidence of contemporary migration. Conservation efforts should provide legal status to corridors, use smart green infrastructure to mitigate development impacts, and restore habitats where connectivity has been lost.     

Effect of atrazine on some aspects of lipid metabolism in fresh water fish

The impact of atrazine, a triazine herbicide, on the lipid metabolism of fish, Sarotherodon mossambica was studied. Significant changes were reported in the lipid profiles of liver and muscle as a function of exposure period.     

Use of Plackett-Burman design for rapid screening of several nitrogen sources,growth/product promoters,minerals and enzyme inducers for the production of alpha-galactosidase by Aspergillus niger MRSS 234 in solid state fermentation system

Five sources of nitrogen, six minerals, six enzyme inducers and one each of growth as well as product promotors were screened by Plackett-Burman design, consisting of a total of 20 experiments for the above 19 sources/categories of medium ingredients, for their effect on the production of alpha-galactosidase by Aspergillus niger MRSS 234 in solid state fermentation system. The enzyme production was recorded from 2 to 5 days of fermentation. Data on enzyme titres was analysed by compatible analysis to obtain regression coefficients and t-ratios. Among the nitrogen sources, urea contributed positively to enzyme production and its effect increased with the fermentation time, in contrast to negative effect of all the ammonium salts used. Corn steep liquor, citric acid and legume seed flours showed significantly positive effects on enzyme production, though lactose showed negative effect upto 3 days of fermentation and then turned positive but not significantly. Calcium chloride and ferrous sulphate showed considerable negative effect, in contrast to mixed effect by other mineral salts studied. Among the legume seed flours, guar and French bean flours showed larger positive effects. The studies allowed the selection of urea, corn steep liquor, guar flour, soy bean flour and citric acid as most promising sources/categories for further optimization studies based on the effects as well as their trend with fermentation time. The use of Plackett-Burman design for rapid screening of large number of nutrients, in a very small number of experiments, for reliable short-listing of a few of most effective sources/categories for further optimization, has been scarce in submerged fermentation and never attempted earlier in solid state fermentation system.Authors are thankful to Dr. S. R. Bhowmik, Director of the institute for interest in the work. M. R. S. Srinivas thanks Council of Scientific and Industrial Research, New Delhi, for the award of junior research fellowship.     

Relationship of Cob characters with Grain Morphology in Maize (Zea mays,Poaceae)

Twenty varieties of maize (Zea mays, Poaceae) were studied through 11 attributes in three to seven randomly selected plants of each variety with a view to understanding the effect of cob characters on technologically desirable grain qualities. Canonical discriminant analysis showed thatproductivity (determined by total grain weight/cob, cob diameter and average grain weight) was the most discriminating among varieties followed by round grains fraction (represented by whole top and middle flat grains, number of rows and grain count/surface area), middle flat grains (composed of middle flat grains and grain count/surface area) and shape of the cob (determined by shape index, total grain weight/cob and cob diameter), which accounted for 35.1, 18.3, 12.2, and 9.8% of the total variance, respectively. In the light of these results, tentative norms have been suggested to evolve maize varieties of superior technological properties and yet retain high productivity. A cylindrical cob of large diameter with highest number of grains/area and smallest possible number of rows together constituted an ideal combination to achieve the objectives. Such possibilities in the light of available information are discussed.     

A novel baker's yeast mediated C-C bond cleavage reaction

Summary A novel baker's yeast mediated C–C bond cleavage reaction was observed during the biotransformation of dimethone derivative of thiophene-2-carboxaldehyde (II) to give the product 2-(2-thienyl methyl)-5,5 dimethyl cyclohexa 1,3-dione (III) in 47% yield.     

Structure-based discovery of a novel inhibitor targeting the β-catenin/Tcf4 interaction

Overactivation or overexpression of β-catenin in the Wnt (wingless) signaling pathway plays an important role in tumorigenesis. Interaction of β-catenin with T-cell factor (Tcf) DNA binding proteins is a key step in the activation of the proliferative genes in response to upstream signals of this Wnt/β-catenin pathway. Recently, we identified a new small molecule inhibitor, named BC21 (C(32)H(36)Cl(2)Cu(2)N(2)O(2)), which effectively inhibits the binding of β-catenin with Tcf4-derived peptide and suppresses β-catenin/Tcf4 driven reporter gene activity. This inhibitor decreases the viability of β-catenin overexpressing HCT116 colon cancer cells that harbor the β-catenin mutation, and more significantly, it inhibits the clonogenic activity of these cells. Down-regulation of c-Myc and cyclin D1 expression, the two important effectors of the Wnt/β-catenin signaling, is confirmed by treating HCT116 cells with BC21. This compound represents a new and modifiable potential anticancer candidate that targets β-catenin/Tcf-4 interaction.