Quantitative analysis of the community structure of tropical amphibian assemblages and its significance to conservation

Amphibian community structure in five tropical sites was studied using dominance, diversity, evenness indices, niche breadth and overlapping scores and association analysis. Ten species of amphibians with average density/ha varying from 8 to 49 in different sites were collected.Rana limnocharis andBufo melanostictus were respectively the dominant amphibia in paddy fields and other sites. Niche breadth scores indicatedRana limnocharis, Bufo melanostictus andRana cyanophlyctis as habitat generalists indicating wide tolerance to environmental gradients. Five frog speciesi.e. Rana tigerina, Microhyla ornata, Ramanella variegata, Uperedon systoma andPolypedates maculatus were considered habitat specialists indicating narrow tolerance to environmental gradients. Niche breadth scores were found to be a function of the cumulative relative abundance value of different species. The niches ofRana limnocharis andRana cyanophlyctis, Bufo melanostictus andBufo stomaticus showed maximum overlapping.Rana tigerina showed maximum niche overlapping withRana variegata in paddy fields and withMicrohyla ornata when all sites were taken together. The coefficient of community index was maximum between the paddy fields and minimum between the paddy fields and forest site.Rana tigerina occurred very sparsely and analysis of data indicates that its population are threatened and require conservation measure.     

Green chemistry appended synthesis,metabolic stability and pharmacokinetic assessment of medicinally important chromene dihydropyrimidinones

A green chemistry approach has been developed for the synthesis of chromene dihydropyrimidinone (CDHPM) using recyclable Fe/Al pillared clay catalyst. Pharmacokinetic parameters like aqueous solubility, lipophilicity, P-glycoprotein (P-gp) ATPase activity, permeability, plasma protein binding, red blood cell (RBC) partitioning, metabolic stability in liver microsomes and in silico computations have been studied for the most potent anticancer chromene dihydropyrimidinone hybrid 1. This compound exhibited low solubility, optimum lipophilicity, no P-gp inhibitory activity, intermediate permeability, high plasma protein binding, low RBC partitioning, acceptable metabolic stability in rat liver microsomes (RLM) as well as human liver microsomes (HLM) with transitional hepatic extraction ratio.     

Biochemical and biologic characterization of exosomes and microvesicles as facilitators of HIV-1 infection in macrophages

Exosomes and microvesicles (MV) are cell membranous sacs originating from multivesicular bodies and plasma membranes that facilitate long-distance intercellular communications. Their functional biology, however, remains incompletely understood. Macrophage exosomes and MV isolated by immunoaffinity and sucrose cushion centrifugation were characterized by morphologic, biochemical, and molecular assays. Lipidomic, proteomic, and cell biologic approaches uncovered novel processes by which exosomes and MV facilitate HIV-1 infection and dissemination. HIV-1 was "entrapped" in exosome aggregates. Robust HIV-1 replication followed infection with exosome-enhanced fractions isolated from infected cell supernatants. MV- and exosome-facilitated viral infections are affected by a range of cell surface receptors and adhesion proteins. HIV-1 containing exosomes readily completed its life cycle in human monocyte-derived macrophages but not in CD4(-) cells. The data support a significant role for exosomes as facilitators of viral infection.     

Phenotypic and molecular characterization of indigenous rhizobia nodulating chickpea in India

In a combined approach of phenotypic and genotypic characterization, 28 indigenous rhizobial isolates obtained from different chickpea growing regions in peninsular and northern India were analyzed for diversity. The field isolates were compared to two reference strains TAL620 and UPM-Ca142 representing M. ciceri and M. mediterraneum respectively. Phenotypic markers such as resistance to antibiotics, tolerance to salinity, temperature, pH, phosphate solubilization ability, growth rate and also symbiotic efficiency showed considerable diversity among rhizobial isolates. Their phenotypic patterns showed adaptations of rhizobial isolates to abiotic stresses such as heat and salinity. Two salt tolerant strains (1.5% NaCl by T1 and T4) with relatively high symbiotic efficiency and two P-solubilising strains (66.7 and 71 microg/ml by T2 and T5) were identified as potential bioinoculants. Molecular profiling by 16S ribosomal DNA Restriction Fragment Length Polymorphism (RFLP) revealed three clusters at 67% similarity level. Further, the isolates were differentiated at intraspecific level by 16S rRNA gene phylogeny. Results assigned all the chickpea rhizobial field isolates to belong to three different species of Mesorhizobium genus. 46% of the isolates grouped with Mesorhizobium loti and the rest were identified as M. ciceri and M. mediterraneum, the two species which have been formerly described as specific chickpea symbionts. This is the first report on characterization of chickpea nodulating rhizobia covering soils of both northern and peninsular India. The collection of isolates, diverse in terms of species and symbiotic effectiveness holds a vast pool of genetic material which can be effectively used to yield superior inoculant strains.     

The first draft of the pigeonpea genome sequence

Pigeonpea (Cajanus cajan) is an important grain legume of the Indian subcontinent, South-East Asia and East Africa. More than eighty five percent of the world pigeonpea is produced and consumed in India where it is a key crop for food and nutritional security of the people. Here we present the first draft of the genome sequence of a popular pigeonpea variety ??Asha??. The genome was assembled using long sequence reads of 454 GS-FLX sequencing chemistry with mean read lengths of >550?bp and >10-fold genome coverage, resulting in 510,809,477?bp of high quality sequence. Total 47,004 protein coding genes and 12,511 transposable elements related genes were predicted. We identified 1,213 disease resistance/defense response genes and 152 abiotic stress tolerance genes in the pigeonpea genome that make it a hardy crop. In comparison to soybean, pigeonpea has relatively fewer number of genes for lipid biosynthesis and larger number of genes for cellulose synthesis. The sequence contigs were arranged in to 59,681 scaffolds, which were anchored to eleven chromosomes of pigeonpea with 347 genic-SNP markers of an intra-species reference genetic map. Eleven pigeonpea chromosomes showed low but significant synteny with the twenty chromosomes of soybean. The genome sequence was used to identify large number of hypervariable ??Arhar?? simple sequence repeat (HASSR) markers, 437 of which were experimentally validated for PCR amplification and high rate of polymorphism among pigeonpea varieties. These markers will be useful for fingerprinting and diversity analysis of pigeonpea germplasm and molecular breeding applications. This is the first plant genome sequence completed entirely through a network of Indian institutions led by the Indian Council of Agricultural Research and provides a valuable resource for the pigeonpea variety improvement.     

Acaricidal activity of Cassia alata against Rhipicephalus (Boophilus) annulatus

Using adult immersion test, the acaricidal activity of ethanolic extracts of leaves of Cassia alata L. was studied against Rhipicephalus (Boophilus) annulatus. The efficacy was assessed by measuring per cent adult mortality, inhibition of fecundity and hatching rate. The ethanolic extract of C. alata produced a concentration dependant increase in the adult tick mortality. The highest mortality (45.8%) and inhibition of fecundity (10.9%) were observed at the highest concentration tested (100 mg/ml). The plant extract did not affect egg hatchability.     

Apoptosis of CD4+CD25high T Cells in Type 1 Diabetes May Be Partially Mediated by IL-2 Deprivation

Background

Type 1 diabetes (T1D) is a T-cell mediated autoimmune disease targeting the insulin-producing pancreatic β cells. Naturally occurring FOXP3⁺CD4⁺CD25^high regulatory T cells (T_regs) play an important role in dominant tolerance, suppressing autoreactive CD4⁺ effector T cell activity. Previously, in both recent-onset T1D patients and β cell antibody-positive at-risk individuals, we observed increased apoptosis and decreased function of polyclonal T_regs in the periphery. Our objective here was to elucidate the genes and signaling pathways triggering apoptosis in T_regs from T1D subjects.

Principal Findings

Gene expression profiles of unstimulated T_regs from recent-onset T1D (n = 12) and healthy control subjects (n = 15) were generated. Statistical analysis was performed using a Bayesian approach that is highly efficient in determining differentially expressed genes with low number of replicate samples in each of the two phenotypic groups. Microarray analysis showed that several cytokine/chemokine receptor genes, HLA genes, GIMAP family genes and cell adhesion genes were downregulated in T_regs from T1D subjects, relative to control subjects. Several downstream target genes of the AKT and p53 pathways were also upregulated in T1D subjects, relative to controls. Further, expression signatures and increased apoptosis in T_regs from T1D subjects partially mirrored the response of healthy T_regs under conditions of IL-2 deprivation. CD4⁺ effector T-cells from T1D subjects showed a marked reduction in IL-2 secretion. This could indicate that prior to and during the onset of disease, T_regs in T1D may be caught up in a relatively deficient cytokine milieu.

Conclusions

In summary, expression signatures in T_regs from T1D subjects reflect a cellular response that leads to increased sensitivity to apoptosis, partially due to cytokine deprivation. Further characterization of these signaling cascades should enable the detection of genes that can be targeted for restoring T_reg function in subjects predisposed to T1D.