Length–weight relationships of nine freshwater fishes from six rivers of the Western Ghats of India

Length–weight relationships (LWRs) were estimated for nine freshwater fish species collected three times using a scoop net (mesh size 0.3–0.5 cm), cast net (mesh size 1–1.5 cm) and gillnet (mesh size 2.5–4.5 cm) from six rivers of the Western Ghats of India during August 2017–October 2018. The b values for LWRs varied from 2.862 to 3.656 (R² > 0.916 and p < 0.0001 for all species).     

In Vitro Modulation of E. coli Community Behavior and Human Innate Immune System by Lantibiotic Nisin

Biofilms are microbial communities with genetically divergent microorganisms. Such communal behavior is known to provide survival benefit to the unicellular organisms in adverse conditions. Pathogenicity of opportunistic bacterial pathogens largely depends on their success in proper quorum establishment and biofilm formation. Thus molecules causing quorum-sensing attenuation, preventing the biofilm formation or instigating preformed biofilm dislodgement could serve as attractive drugs/drug supplements. Here we investigate the effect of nisin??type A lantibiotic naturally produced by Lactococcus lactis??on laboratory developed Escherichia coli biofilms and on isolated human neutrophils. Activity evaluation was done on the biofilms of clinical isolates of E. coli, developed on glass slides in a simple static bioreactor design. Nisin not only inhibited the formation but also effectively dislodged the preformed E. coli biofilms developed on glass surfaces. Presence of nisin also demonstrated a significant decrease in the expression of E. coli virulence factors viz. hemolysin and curli expression. The microorganisms dislodged from the biofilms and set free in the circulation of infected host might later reassociate to form new biofilms after nisin clearance from circulation. Thus complete eradication of infective bacterium will depend on stimulatory effect of nisin (if any) on human immune system cells. Therefore modulation of human neutrophil activity by nisin was also evaluated. Presence of nisin induced neutrophil extracellular trap (NET) formation or NETosis in a manner similar to that demonstrated by LPS (lipopolysaccharide) in vitro. Our results thus present nisin as a plausible molecule to be used in treatment of chronic bacterial infections as it indicated increased fitness for the same.     

Asparagus racemosus cell cultures: a source for enhanced production of shatavarins and sarsapogenin

Asparagus racemosus is an important monocot medicinal plant that is in great demand for its steroidal saponins called shatavarins. This study was initiated to optimize the conditions for production of shatavarins in cell cultures of A. racemosus in a modified Murashige and Skoog (MS) medium supplemented with six different combinations of growth regulators. Biomass accumulation was correlated with saponin production over a 30-d culture cycle. Biomass and saponin accumulation patterns were dependent on combinations of growth regulators and the pH of the medium. Maximum levels of saponin and biomass accumulation were recorded on day 25 of the culture cycle within a pH range of 3.4 to 5.6. Total saponin produced by the in vitro cultures was 20-fold higher than amounts produced by cultivated plants. Saponin accumulation was not a biomass-associated phenomenon; cultures which showed the highest biomass accumulation were not the highest saponin accumulators. Maximum biomass (28.30 ± 0.29 g l⁻¹) and maximum levels of shatavarin IV(11.48 ± 0.61 mg g⁻¹) accumulation was found using a medium containing 2.0 mg l⁻¹ 2,4-D, 2 g l⁻¹ casein hydrolysate and 0.005% pectinase. The highest levels of sarsapogenin, secreted and intracellular (4.02 ± 0.09 mg g⁻¹), accumulated using a medium containing 1.0 mg l⁻¹ NAA, 1.0 mg l⁻¹ 2,4-D, 0.5 mg l⁻¹ BAP, 2 g l⁻¹ casein hydrolysate and 0.005% pectinase, after 25 d. Shatavarins were secreted into the medium and can be isolated easily for further purification.     

Immunomodulatory efficacy of nisin—a bacterial lantibiotic peptide

Nisin is a peptide bacteriocin, grouped under the category of lantibiotics. It is naturally produced by Lactococcus lactis to eliminate other competing gram‐positive bacteria from its vicinity. Moreover under certain conditions it is reported to be effective against a broad range of gram‐negative bacteria as well. Thus, it has been widely used as a safe food preservative especially in the dairy industry. Because of its wide‐scale consumption, its effect on eukaryotic cells should be of great concern. Here we examine the immunomodulatory efficacy of nisin in vitro. MTT‐based cytotoxicity assay demonstrated nisin's cytotoxicity on human T‐cell lymphoma Jurkat cells, Molt‐4 cells and freshly cultured human lymphocytes at over 200 µM concentration (IC₅₀225 µM ). The cell death mechanism induced by nisin in all these lymphocyte types was independent of oligonucleosomal DNA fragmentation, as analyzed by agarose gel electrophoresis and comet assay. Additionally, scanning electron microscope and fluorescence microscopy demonstrated the ability of nisin to activate human PMNs in vitro. Nisin‐activated neutrophils extruded intact nuclear chromatin to form NETs, well known for neutralization of virulence factors and extermination of bacterial pathogens. Nisin's presence also elevated neutrophil intracellular superoxide levels, normally produced by activated NADPH oxidase and prerequisite to NET formation. These nisin‐induced responses in cellular representatives of two separate branches of human immune system—adaptive and innate—although leading to cell death, did not include DNA fragmentation. From these findings, we propose that nisin might trigger similar AICD mechanisms in lymphocytes and neutrophils, different from conventional apoptosis which involves DNA fragmentation. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.     

A B-spline based heterogeneous modeling and analysis of proximal femur with graded element

Bone is a complex biological tissue and natural heterogeneous object. The main objective of this study is to simulate quasi-static loading of bio-objects like human femur with B-spline based modeling and its 3D finite element analysis with graded element. B-spline surface representation method is extended to represent material composition to develop heterogeneous solid model of proximal femur. Lagrangian graded element is used to assign inhomogeneous isotropic elastic properties in finite element model to improve the performance. Convergence study is carried out with finite element model in single leg stance load condition. To test the feasibility of the model, sensitivity of simulation is investigated. To validate the model, numerical results are compared with those of an experimental work for the same specimen in simple stance load condition obtained from one of the reference paper. Good agreement is achieved for vertical displacement and strains in most of the locations.