Carbohydrates and polyphenolics of extracts from genetically altered plant acts as catalysts for in vitro synthesis of silver nanoparticle.

Eco-friendly biosynthetic approach for silver nanoparticles production using plant extracts is an exciting advancement in bio-nanotechnology and has been successfully attempted in nearly 41 plant species. However, an established model plant system for systematically unraveling the biochemical components required for silver nanoparticles production is lacking. Here we used Arabidopsis thaliana as the model plant for silver nanoparticles biosynthesis in vitro. Employing biochemical, spectroscopic methods, selected mutants and over-expressor plants of Arabidopsis involved in pleotropic functions and sugar homeostasis, we show that carbohydrates, polyphenolics and glyco-proteins are essential components which stimulated silver nanoparticles synthesis. Using molecular genetics as a tool, our data enforces the requirement of sugar conjugated proteins as essentials for AgNPs synthesis over protein alone. Additionally, a comparative analysis of AgNPs synthesis using the aqueous extracts of some of the plant species found in a brackish water ecosystem (Gracilaria, Potamogeton, Enteromorpha and Scendesmus) were explored. Plant extract of Potamogeton showed the highest potential of nanoparticles production comparable to that of Arabidopsis among the species tested. Silver nanoparticles production in the model plant Arabidopsis not only opens up a possibility of using molecular genetics tool to understand the biochemical pathways and components in detail for its synthesis.

Innate CD8αα+ lymphocytes enhance anti-CD40 antibody-mediated colitis in mice.

INTRODUCTION: Immune responses in the intestines require tight regulation to avoid uncontrolled inflammation. We previously described an innate lymphocyte population in the intestinal epithelium (referred to as innate CD8αα+ , or iCD8α cells) that can protect against gastrointestinal infections such as those mediated by Citrobacter rodentium. METHODS: Here, we have evaluated the potential contribution of these cells to intestinal inflammation by analyzing inflammation development in mice with decreased numbers of iCD8α cells. We also determined the potential of iCD8α cells to secrete granzymes and their potential role during inflammatory processes. RESULTS: We found that iCD8α cells play a pro-inflammatory role in the development of disease in a colitis model induced by anti-CD40 antibodies. We further found that the effects of iCD8α cells correlated with their capacity to secrete granzymes. We also observed that the pro-inflammatory properties of iCD8α cells were controlled by interactions of CD8αα homodimers on these cells with the thymus leukemia antigen expressed by intestinal epithelial cells. CONCLUSIONS: Our findings suggest that iCD8α cells modulate inflammatory responses in the intestinal epithelium, and that dysregulation of iCD8α cells effector functions may enhance disease. We propose that one of the mechanism by which iCD8α cells enhance inflammation is by the secretion of granzymes, which may promote recruitment of infiltrating cells into the epithelium.

Environmental stress influencing plant development and flowering.

Plants are sessile organisms and unlike animals, cannot run away from adverse environmental conditions. Therefore, they have evolved sophisticated signaling and protective systems to overcome sub-lethal stress situations. Although, effect of stress on physiology and morphology were studied earlier, the research on molecular mechanisms of stress response is albeit new. Studies at the molecular level on stress physiology reveal that, many stress-induced pathways converge downstream or interact significantly. Abiotic stress factors regulate the extent and pattern of developmental programme. The timing of transition from vegetative to flowering phase, which is vital for survival and reproductive success, is often altered under various stresses. Unraveling the mechanisms by which different environmental stresses induce their effects and how tolerance to stress is achieved is an active area of research. Enhancing stress tolerance, especially in crop plants is an area of prime importance. In this review, we focus on stress responses induced by temperatures, high and low light intensities, UV radiation, drought and salinity stress and summarize the recent advancements by highlighting the underlying molecular pathways and processes.