Habitat Ecology and Ichthyofaunal Diversity of Two Creeks and Their Associated Streams from Port Blair, South Andaman Islands

Habitat ecology and ichthyofaunal diversity were analyzed from two creeks and their associated streams in Port Blair: one was perennial and the other one was seasonal. Various habitat types like riffles, pools, and major and minor bends in both streams were studied. The perennial stream has 12 riffles and 14 pools from head point to the entering point of the creek. The seasonal stream has 15 riffles and 13 pools from the starting point to the sink. The perennial stream was found to have higher ichthyofaunal diversity than the seasonal stream: 1701 individuals constituting 8 orders, 30 families, 42 genera, and 54 species were recorded. Among these, 395 specimens represented by 21 species were found in perennial stream, 291 specimens with 11 species were found in seasonal stream, 863 specimens by 48 species were noted in creek, and 152 specimens constituting 14 species in sink were recorded. The physicochemical parameters of the habitats showed more or less a similar trend. The average dissolved oxygen value of the perennial stream was higher than that of the seasonal stream. Higher temperature values were noted during the postmonsoon season. This study has indicated a wide lacuna in the knowledge of the fresh water habitats and their inhabitants on these islands

Food and Feeding Dynamics of Stolephorus commersonnii

The feeding dynamics of Stolephorus commersonnii along the coastal waters of South Andaman during October, 2011, to September, 2012, were examined by employing “point’s method.” The results of the present study has shown that S. commersonnii mainly is a planktonivorous carnivore chiefly feeding in the pelagic realm on planktonic crustaceans, bivalves, gastropods, and miscellaneous food items. The copepods formed the main prey item, contributing their maximum during November 2011 (47.55%) and lowest in December (24.21%) which was confirmed by various food preference indices. There was no significant seasonal variation in the feeding preference. Lower length classes fed mainly on planktonic copepods and amphipods whereas the higher length classes fed mainly on postlarval shrimps and planktonic crustaceans like Lucifer sp. and Acetes sp. Feeding intensity was seasonal, but independent of the length of fish. Gastrosomatic index was highest during monsoon, indicating active feeding. During the period when a maximum percentage of fully mature individuals were present, the feeding intensity was found to be low. The trophic level of this species was found to be 2.96±0.11

Functional group interactions of a 5-HT3R antagonist

Background: Lerisetron, a competitive serotonin type 3 receptor (5-HT 3R) antagonist, contains five functional groups capable of interacting with amino acids in the 5-HT3R binding site. Site directed mutagenesis studies of the 5-HT3AR have revealed several amino acids that are thought to form part of the binding domain of this receptor. The specific functional groups on the ligand that interact with these amino acids are, however, unknown. Using synthetic analogs of lerisetron as molecular probes in combination with site directed mutagenesis, we have identified some of these interactions and have proposed a model of the lerisetron binding site. Results: Two analogs of lerisetron were synthesized to probe 5-HT3R functional group interactions with this compound. Analog 1 lacks the N1 benzyl group of lerisetron and analog 2 contains oxygen in place of the distal piperazine nitrogen. Both analogs show significantly decreased binding affinity to wildtype 5-HT3ASRs. Mutations at W89, R91, Y142 and Y152 produced significant decreases in binding compared to wildtype receptors. Binding affinities of analogs 1 and 2 were altered only by mutations at W89, and Y152. Conclusions: Based on the data obtained for lerisetron and analogs 1 and 2, we have proposed a tentative model of the lerisetron binding pocket of the 5-HT3ASR. According to this model, The N-benzyl group interacts in a weak interaction with R91 while the benzimidazole group interacts with W89. Our data support an interaction of the distal amino nitrogen with Y142 and Y152

Functional group interactions of a 5-HT(3)R antagonist

BACKGROUND: Lerisetron, a competitive serotonin type 3 receptor (5-HT(3)R) antagonist, contains five functional groups capable of interacting with amino acids in the 5-HT(3)R binding site. Site directed mutagenesis studies of the 5-HT(3A)R have revealed several amino acids that are thought to form part of the binding domain of this receptor. The specific functional groups on the ligand that interact with these amino acids are, however, unknown. Using synthetic analogs of lerisetron as molecular probes in combination with site directed mutagenesis, we have identified some of these interactions and have proposed a model of the lerisetron binding site. RESULTS: Two analogs of lerisetron were synthesized to probe 5-HT(3)R functional group interactions with this compound. Analog 1 lacks the N1 benzyl group of lerisetron and analog 2 contains oxygen in place of the distal piperazine nitrogen. Both analogs show significantly decreased binding affinity to wildtype 5-HT(3AS)Rs. Mutations at W89, R91, Y142 and Y152 produced significant decreases in binding compared to wildtype receptors. Binding affinities of analogs 1 and 2 were altered only by mutations at W89, and Y152. CONCLUSIONS: Based on the data obtained for lerisetron and analogs 1 and 2, we have proposed a tentative model of the lerisetron binding pocket of the 5-HT(3AS)R. According to this model, The N-benzyl group interacts in a weak interaction with R91 while the benzimidazole group interacts with W89. Our data support an interaction of the distal amino nitrogen with Y142 and Y152

Genetic variation in South Indian castes: evidence from Y-chromosome, mitochondrial, and autosomal polymorphisms

Background: Major population movements, social structure, and caste endogamy have influenced the genetic structure of Indian populations. An understanding of these influences is increasingly important as gene mapping and case-control studies are initiated in South Indian populations. Results: We report new data on 155 individuals from four Tamil caste populations of South India and perform comparative analyses with caste populations from the neighboring state of Andhra Pradesh. Genetic differentiation among Tamil castes is low (R = 0.96% for 45 autosomal short tandem repeat (STR) markers), reflecting a largely common origin. Nonetheless, caste- and continent-specific patterns are evident. For 32 lineage-defining Y-chromosome SNPs, Tamil castes show higher affinity to Europeans than to eastern Asians, and genetic distance estimates to the Europeans are ordered by caste rank. For 32 lineage-defining mitochondrial SNPs and hypervariable sequence (HVS) 1, Tamil castes have higher affinity to eastern Asians than to Europeans. For 45 autosomal STRs, upper and middle rank castes show higher affinity to Europeans than do lower rank castes from either Tamil Nadu or Andhra Pradesh. Local between-caste variation (Tamil Nadu R = 0.96%, Andhra Pradesh R = 0.77%) exceeds the estimate of variation between these geographically separated groups (R = 0.12%). Low, but statistically significant, correlations between caste rank distance and genetic distance are demonstrated for Tamil castes using Y-chromosome, mtDNA, and autosomal data. Conclusion: Genetic data from Y-chromosome, mtDNA, and autosomal STRs are in accord with historical accounts of northwest to southeast population movements in India. The influence of ancient and historical population movements and caste social structure can be detected and replicated in South Indian caste populations from two different geographic regions

Spatial organization and time dependence of Jupiter's tropospheric temperatures, 1980-1993

The spatial organization and time dependence of Jupiter's temperature near 250-millibar pressure were measured through a jovian year by imaging thermal emission at 18 micrometers. The temperature field is influenced by seasonal radiative forcing, and its banded organization is closely correlated with the visible cloud field. Evidence was found for a quasi-periodic oscillation of temperatures in the Equatorial Zone, a correlation between tropospheric and stratospheric waves in the North Equatorial Belt, and slowly moving thermal features in the North and South Equatorial Belts. There appears to be no common relation between temporal changes of temperature and changes in the visual albedo of the various axisymmetric bands