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.     

Metastasis-associated alterations in phospholipids and fatty acids of human prostatic adenocarcinoma cell lines.

Metastatic variants of human prostatic adenocarcinoma cell lines (DU-145, LNCaP, and ND-1) were studied by using soft agar colony forming efficiency, nude mice tumorigenicity, in vitro invasion assay, and type IV collagenase assay. The DU-145 and ND-1 cell line showed higher metastatic potential than LNCaP. Lipids from DU-145, ND-1, and LNCaP cells were extracted and analyzed by thin-layer chromatography and gas-liquid chromatography. The major lipids were phosphatidylcholine, phosphatidylethanolamine, sphingomyelin, fatty acids, and cholesterol. The sphingomyelin level was significantly higher in highly metastatic cells (DU-145 and ND-1) compared with the lower metastatic variant (LNCaP). The increase in the synthetic pathway and decrease in degradation pathway of sphingomyelin in microsomal fractions was sufficient to account for the measured increase in sphingomyelin in DU-145 cells compared with LNCaP cells. The major fatty acids of these lipids were palmitic (16:0), stearic (18:0), oelic (18:1), and arachidonic acid (20:4). The arachidonic acid level was significantly decreased in DU-145 and ND-1 compared with LNCaP cells. Electron microscopic studies showed no significant changes in the morphology of DU-145, ND-1, and LNCaP cells. The results of these investigations demonstrate for the first time that sphingomyelin and arachidonic acid contents are different in high and low metastatic variants of human prostatic adenocarcinoma cell lines.     

The hydrophobic membrane-spanning sequences of the gp52 glycoprotein are required for the pathogenicity of Friend spleen focus-forming virus.

Friend spleen focus-forming virus (SFFV) codes for a transport-defective envelope glycoprotein designated gp52, which is responsible for the leukemogenic properties of the virus. gp52 is a monotopic integral membrane protein anchored in the membrane by a stretch of hydrophobic amino acid residues located near the carboxy terminus of the molecule. We have constructed a mutant SFFV envelope gene in which the sequences that code for the hydrophobic membrane-spanning domain have been deleted, and we expressed this gene by using recombinant vaccinia virus vectors or retroviral vectors. The mutant SFFV envelope gene was found to encode a truncated glycoprotein (gp52t) which was also transport defective; a majority of gp52t remained cell associated, while a small proportion of the molecules underwent oligosaccharide processing. The processed form of gp52t was secreted from the cells. Retroviral vectors carrying the mutant SFFV envelope gene were found to be nonpathogenic in adult mice. These results indicate that the hydrophobic membrane-spanning region of gp52 is required for pathogenicity of SFFV and suggest that these sequences may play a role in signal transduction. The results also indicate that the transport defect of SFFV gp52 is due to structural features of the ectodomain of the molecule.     

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.     

Histology of the pituitary gland of the grey mullet, Mugil cephalus L.

The present communication deals with a histological study of the pituitary gland of the teleost fish Mugil cephalus , found in the estuarine waters of Cochin area. Six different cell types were identified in the pituitary gland on the basis of their grouping, distribution and staining properties. The prolactin and the TSH cells (thyroid stimulating hormone producing cells or thyrotrops) were identified in the rostral pars distalis and the ACTH cells (adrenocorticotropic hormone producing cells or corticotrops) in the interphase between the neurohypophysis and the rostral pars distalis. The STH cells (somatotropic hormone producing cells or somatotrops) and the gonadotropic cells were distinguished in the proximal pars distalis and the MSH cells (melanin stimulating hormone producing cells or melanotrops) in the pars intermedia.     

Regeneration of plantlets from the callus of stem segments of adult plants of Ficus religiosa L.

Stem segments of adult plants of Ficus religiosa L. cultured on MS medium containing 1.0 mg/l 2,4-D produced callus. Shoots were regenerated when the induced calli were transferred to medium supplemented with 0.05 to 2.0 mg/l BAP. Callus derived shoots produced roots and developed into plantlets when transferred to medium supplemented with 1.0 mg/l NAA.Abbreviations MS Murashige and Skoog (1962) - BAP 6-benzylaminopurine - NAA naphthaleneacetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid