Comparative Genomic Analyses of Streptococcus pseudopneumoniae Provide Insight into Virulence and Commensalism Dynamics

Streptococcus pseudopneumoniae (SPPN) is a recently described species of the viridans group streptococci (VGS). Although the pathogenic potential of S. pseudopneumoniae remains uncertain, it is most commonly isolated from patients with underlying medical conditions, such as chronic obstructive pulmonary disease. S. pseudopneumoniae can be distinguished from the closely related species, S. pneumoniae and S. mitis, by phenotypic characteristics, including optochin resistance in the presence of 5% CO₂, bile insolubility, and the lack of the pneumococcal capsule. Previously, we reported the draft genome sequence of S. pseudopneumoniae IS7493, a clinical isolate obtained from an immunocompromised patient with documented pneumonia. Here, we use comparative genomics approaches to identify similarities and key differences between S. pseudopneumoniae IS7493, S. pneumoniae and S. mitis. The genome structure of S. pseudopneumoniae IS7493 is most closely related to that of S. pneumoniae R6, but several recombination events are evident. Analysis of gene content reveals numerous unique features that distinguish S. pseudopneumoniae from other streptococci. The presence of loci for competence, iron transport, pneumolysin production and antimicrobial resistance reinforce the phylogenetic position of S. pseudopneumoniae as an intermediate species between S. pneumoniae and S. mitis. Additionally, the presence of several virulence factors and antibiotic resistance mechanisms suggest the potential of this commensal species to become pathogenic or to contribute to increasing antibiotic resistance levels seen among the VGS.     

Inferences from the ADMET analysis of predicted inhibitors to Follicle Stimulating Hormone in the context of infertility

Follicle stimulating hormone (FSH) is a glycoprotein secreted by gonadotrophs of the anterior pituitary gland that regulates reproduction in mammals. FSH targets its receptor (FSHR) expressed only on grannulosa cells and induce the maturation of ovarian follicles in females. The levels of both FSH and FSHR rise until the middle of estrus cycle and then falls on level at the time of ovulation. It is associated with stimulated sertoli cell proliferation in testes and supports spermatogenesis in males. The interaction between the polypeptide FSH hormone and its corresponding receptor is highly selective. Therefore, it is of interest to inhibit FSH in the context of infertility. The structure of FSH (PDB ID: 1XWD) is screened using molecular docking techniques against the ZINC database (a database of 2.7 million compounds) with reference to known standard compounds. This exercise identifies compounds with better binding and ADMET (Absorption, Digestion, Metabolism, Excretion and Toxicity) properties compared to known standard compounds. These observations find application for the consideration of such compounds for further validation towards inhibiting the FSH.     

Micro-cloning of an economic rattan palm Calamus thwaitesii for eco-restoration programme

Axillary shoots were induced from shoot tip of Calamus thwaitesii suckers on Murashige and Skoog medium supplemented with 0.4 mg/L N6-benzylaminopurine and 0.1 mg/L each of thidiazuron and α-naphthaleneacetic acid (NAA). The shoots initiated were subcultured to fresh media of the same composition for shoot multiplication and multiplied shoots were transferred to half strength MS hormone-free media for shoot elongation. The elongated shoots (～5cm) were then re-cultured to the media supplemented with 3.0 mg/L indole-3-butyric acid/4.0 mg/L NAA to raise plantlets which were subsequently analysed for genetic fidelity using inter simple sequence repeat markers. Out of 183 bands scored, 178 bands were monomorphic indicating 97.2% similarity. The observed low level of polymorphism between genotypes supports genetic consistency of these micro-clones that are likely to be genetically true to their parental origin. The clones thus obtained were hardened in the specially fabricated mist house at 29 ±2°C and 80±5% relative humidity for 3 months followed by shifting to green house for another 3 months of nursery establishment. The established plants when reintroduced to the selected forest segments of the Western Ghats, Kerala (India) showed 79.3% survival rate after 2 years of field transfer. The viable and highly reproducible in vitro cloning protocol demonstrated here for the first time can be used for the production of elite female clones for aforestation activities and sustained delivery of high quality raw materials to cane processing units for strengthening cane industry.     

Lead and Cadmium Co-exposure Mediated Toxic Insults on Hepatic Steroid Metabolism and Antioxidant System of Adult Male Rats

The redox status and steroid metabolism of liver of adult male rat exposed to lead (Pb) and cadmium (Cd) either alone or in co-exposure (0.025 mg/kg body weight intraperitoneally/15 days) was studied. Pb and Cd significantly accumulated in the liver. The activity of steroid metabolizing enzymes 17-βhydroxysteroid oxidoreductase and uridine diphosphate–glucuronyltransferase were decreased in experimental animals. 17-β-Hydroxysteroid dehydrogenase was reduced to 33%, 38%, and 24% on treatment of Pb, Cd, and co-exposure (Pb + Cd). Furthermore, the activity of uridine diphosphate–glucuronosyltransferase was significantly reduced to 27% (Pb exposure), 36% (Cd exposure), and 25% (co-exposure of Pb + Cd). Cd exposure exhibited more toxic effect than Pb, while co-exposure demonstrated the least. The activities of antioxidant enzymes, superoxide dismutase, catalase, glutathione reductase, and glucose-6-phosphate dehydrogenase decreased and glutathione peroxidase increased in mitochondrial and post-mitochondrial fractions. The level of lipid peroxidation increased, and cellular glutathione concentration decreased. Hepatic DNA was decreased, whereas RNA content and the activity of alanine transaminase remained unchanged. Histological studies revealed that only Cd-exposed groups exhibited cytotoxic effect. These results suggest that when Pb and Cd are present together in similar concentrations, they exhibited relatively decreased toxic effect when compared to lead and cadmium in isolation with regard to decreased steroid metabolizing and antioxidant enzyme activities. This seems that the toxic effect of these metals is antagonized by co-exposure due to possible competition amongst Pb and Cd for hepatic accumulation.     

Neutralization of radical toxicity by temperature-dependent modulation of extracellular SOD activity in coral bleaching pathogen Vibrio shiloi and its role as a virulence factor

Vibrio shiloi is the first and well-documented bacterium which causes coral bleaching, particularly, during summer, when seawater temperature is between 26 and 31°C. Coral bleaching is the disruption of the symbiotic association between coral hosts and their photosynthetic microalgae zooxanthellae. This is either due to lowered resistance in corals to infection or increased virulence of the bacterium at the higher sea surface temperature. The concentration of the oxygen and resulting oxygen radicals produced by the zooxanthellae during photosynthesis are highly toxic to bacteria, which also assist corals in resisting the infection. Hence, in this study we examined the effect of different temperatures on the activity of a novel extracellular SOD in V. shiloi. We also partially characterized the SOD and clearly confirmed that the extracellular SOD produced by V. shiloi is Mn–SOD type, as it was not inhibited by H₂O₂ or KCN. Performing chemical susceptibility killing assay, we confirmed that extracellular SOD may act as first line of defense for the bacteria against the reactive oxygen species. Since, increased activity of novel Mn–SOD at higher temperature, leads to the neutralization of radical toxicity and facilitates the survival of V. shiloi. Hence, the extracellular Mn–SOD may be considered as a virulence factor.     

Discovery of potent,selective, and orally bioavailable 3H-spiro[isobenzofuran-1,4′-piperidine] based melanocortin subtype-4 receptor agonists

Design, synthesis, and SAR of a series of 3H-spiro[isobenzofuran-1,4′-piperidine] based compounds as potent, selective and orally bioavailable melanocortin subtype-4 receptor (MC4R) agonists are disclosed.     

Intrinsic electrophilicity of the 4-methylsulfonyl-2-pyridone scaffold in glucokinase activators: Role of glutathione-S-transferases and in vivo quantitation of a glutathione conjugate in rats

Previous studies on the in vitro metabolism of 4-alkylsulfonyl-2-pyridone-based glucokinase activators revealed a facile, non-enzymatic displacement of the 4-alkylsulfonyl group by glutathione. In the present studies, a role for glutathione-S-transferases (GST) as catalysts in the desulfonylation reaction was demonstrated using a combination of human liver microsomes, human liver cytosol and human GSTs. The identification of a glutathione conjugate in circulation following intravenous administration of a candidate 4-methylsulfonyl-2-pyridone to rats confirmed the relevance of the in vitro findings.