Kotumsar Cave biodiversity: a review of cavernicoles and their troglobiotic traits

The evolutionary adaptations of the organisms which inhabit the unusual and fragile ecosystems within caves are of inherent interest to both biologists and laymen. Cave organisms generally develop a high degree of physiological and behavioural adaptation for survival in the subterranean environment. The Kotumsar Cave is biologically the best known cave in India and has attracted interest from researchers from all over the world. This paper assesses the ecological community and overall habitat of the cave. This is based on long-term field observations and the review of the extensive literature on Kotumsar. For each species, features indicative of evolutionary adaptation to the cave environment are noted and conclusions drawn regarding the status of the species as a cavernicole. Several species of this cave are yet to get a proper study for correct taxonomic position although they have apparent troglomorphic dispositions. Several species which are highly endemic to this cave are probably in verge of its extinction. A serious measure to conserve the whole biodiversity has been suggested.     

Seasonal distribution, parity, resting, host-seeking behavior and association of malarial parasites of Anopheles stephensi Liston in Kolkata, West Bengal

Indoor resting and human-landing mosquito collections were conducted at selected localities in Kolkata, India to determine resting and host-seeking behavior, night biting activity, seasonal distributions and malaria infection rates. During a two-year study (2006–2007), 5123 and 1716 female mosquitoes were captured in indoor-resting and human-landing collections, respectively, from two types of residences (brick built rooms, temporary huts). Regression analysis demonstrated that the abundance of indoor resting An. stephensi was positively correlated with ambient temperature and relative humidity. The average duration of the gonotrophic cycle for laboratory-reared An. stephensi was about 4 days. Average proportion of parous An. stephensi , daily survival and daily mortality rates were 46%, 82% and 18%, respectively. Plasmodium vivax sporozoite infections were detected in the salivary glands of two wild-caught An. stephensi (sporozoite rate 2.2%) and one An. annularis (sporozoite rate 1.5%). No P. falciparum infections were detected. Oocyst infections were observed in one An. annularis mosquito (oocyst rate 1.5%).     

A positive feedback-based gene circuit to increase the production of a membrane protein

Background

Membrane proteins are an important class of proteins, playing a key role in many biological processes, and are a promising target in pharmaceutical development. However, membrane proteins are often difficult to produce in large quantities for the purpose of crystallographic or biochemical analyses.

Results

In this paper, we demonstrate that synthetic gene circuits designed specifically to overexpress certain genes can be applied to manipulate the expression kinetics of a model membrane protein, cytochrome bd quinol oxidase in E. coli, resulting in increased expression rates. The synthetic circuit involved is an engineered, autoinducer-independent variant of the lux operon activator LuxR from V. fischeri in an autoregulatory, positive feedback configuration.

Conclusions

Our proof-of-concept experiments indicate a statistically significant increase in the rate of production of the bd oxidase membrane protein. Synthetic gene networks provide a feasible solution for the problem of membrane protein production.     

TGFβ enforces activation of eukaryotic elongation factor-2 (eEF2) via inactivation of eEF2 kinase by p90 ribosomal S6 kinase (p90Rsk) to induce mesangial cell hypertrophy

eEF2 phosphorylation is under tight control to maintain mRNA translation elongation. We report that TGFβ activates eEF2 by decreasing eEF2 phosphorylation and simultaneously increasing eEF2 kinase phosphorylation. Remarkably, inhibition of Erk1/2 blocked the TGFβ-induced dephosphorylation and phosphorylation of eEF2 and eEF2 kinase. TGFβ increased phosphorylation of p90Rsk in an Erk1/2-dependent manner. Inactive p90Rsk reversed TGFβ-inhibited phosphorylation of eEF2 and suppressed eEF2 kinase activity. Finally, inactive p90Rsk significantly attenuated TGFβ-induced protein synthesis and hypertrophy of mesangial cells. These results present the first evidence that TGFβ utilizes the two layered kinase module Erk/p90Rsk to activate eEF2 for increased protein synthesis during cellular hypertrophy.     

Development of NaCl-tolerant strain in Chrysanthemum morifolium Ramat. through in vitro mutagenesis

One NaCl-tolerant chrysanthemum (Chrysanthemum morifolium Ramat.) variant (E2) has been developed in a stable form through IN VITRO mutagenesis using ethylmethane sulfonate (EMS) as the chemical mutagen. Salt tolerance was evaluated by the capacity of the plant to maintain both flower quality and yield under stress conditions. Enhanced tolerance of the E2 variant has been attributed to the increased activity of superoxide dismutase (SOD), ascorbate peroxidase (APX), and dehydroascorbate reductase (DHAR), and, to a lesser extent of membrane damage than NaCl-treated control plants. Isoform analysis revealed that an increase in total SOD activity in the E2 variant was solely due to significant activation of the Cu/Zn isoform. Elevated levels of carotenoids and ascorbate in E2 leaves have been reflected in their higher free radical scavenging capacity (RSC) expressed in terms of DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging ability. Data reflect that a proper balance between enzymatic and non-enzymatic defence systems is required for combating salinity stress in chrysanthemum. Better performance of the E2 progeny under same salinity stress condition, even in the second year, confirms the genetic stability of the salt-tolerance character. On the whole, the E2 variant, developed through 0.025 % EMS treatment, might be considered as a NaCl-tolerant strain showing positive characters towards NaCl stress.     

Role of protein kinase C-mediated protein phosphorylation in mitochondrial translocation of mouse CYP1A1, which contains a non-canonical targeting signal

A large number of mitochondrial proteins lack canonical mitochondrial-targeting signals. The bimodal transport of cytochromes P450 (CYPs) to endoplasmic reticulum and mitochondria (MT), reported previously by us, likely represents one mode of non-canonical protein targeting to MT. Herein, we have studied the mechanism of mouse MT-CYP1A1 targeting to gain insight into the regulatory features and evolutionary conservation of bimodal targeting mechanism. Mouse MT-CYP1A1 consists of two NH2-terminal-truncated molecular species, +91A1 and +331A1. Mutations Pro-2 --> Leu and Tyr-5 --> Leu, which increase the signal recognition particle (SRP) binding, diminished MT targeting of the protein in intact cells. By contrast, mutations Leu-7 --> Asn and Leu-17 --> Asn, which decreased SRP-binding affinity, enhanced MT targeting, thus suggesting that SRP binding is an important regulatory step that modulates bimodal targeting. Protein kinase C (PKC)-mediated phosphorylation of nascent chains at Thr-35 vastly decreased affinity for SRP binding suggesting an important regulatory step. In support of these results, COS cell transfection experiments show that phosphomimetic mutation Thr-35 --> Asp or induced cellular PKC caused increased CYP1A1 targeting to MT and correspondingly lower levels to the endoplasmic reticulum. Results suggest evolutionary conservation of chimeric signals and bimodal targeting of CYP1A1 in different species. The mouse MT-CYP1A1 is an extrinsic membrane protein, which exhibited high FDX1 plus FDXR-mediated N-demethylation of a number of tricyclic antidepressants, pain killers, anti-psychotics, and narcotics that are poor substrates for microsomal CYP1A1.     

Genomic insights into positive selection

The traditional way of identifying targets of adaptive evolution has been to study a few loci that one hypothesizes a priori to have been under selection. This approach is complicated because of the confounding effects that population demographic history and selection have on patterns of DNA sequence variation. In principle, multilocus analyses can facilitate robust inferences of selection at individual loci. The deluge of large-scale catalogs of genetic variation has stimulated many genome-wide scans for positive selection in several species. Here, we review some of the salient observations of these studies, identify important challenges ahead, consider the limitations of genome-wide scans for selection and discuss the potential significance of a comprehensive understanding of genomic patterns of selection for disease-related research.