T Cell Factor-1 Controls the Lifetime of CD4+ CD8+ Thymocytes In Vivo and Distal T Cell Receptor α-Chain Rearrangement Required for NKT Cell Development

Natural killer T (NKT) cells are a component of innate and adaptive immune systems implicated in immune, autoimmune responses and in the control of obesity and cancer. NKT cells develop from common CD4+ CD8+ double positive (DP) thymocyte precursors after the rearrangement and expression of T cell receptor (TCR) Vα14-Jα18 gene. Temporal regulation and late appearance of Vα14-Jα18 rearrangement in immature DP thymocytes has been demonstrated. However, the precise control of lifetime of DP thymocytes in vivo that enables distal rearrangements remains incompletely defined. Here we demonstrate that T cell factor (TCF)-1, encoded by the Tcf7 gene, is critical for the extended lifetime of DP thymocytes. TCF-1-deficient DP thymocytes fail to undergo TCR Vα14-Jα18 rearrangement and produce significantly fewer NKT cells. Ectopic expression of Bcl-x_L permits Vα14-Jα18 rearrangement and rescues NKT cell development. We report that TCF-1 regulates expression of RORγt, which regulates DP thymocyte survival by controlling expression of Bcl-x_L. We posit that TCF-1 along with its cofactors controls the lifetime of DP thymocytes in vivo.     

A thermoluminescence study of the effects of nitrite on photosystem II in spinach thylakoids.

The site of action of nitrite on PS II was investigated by measuring the TL profile of nitrite-treated spinach thylakoid membranes. Three bands were observed in control, which were identified as the Q band (7 degrees C), the B band (24 degrees C) and the C band (57 degrees C). In the presence of 20 mmol/L nitrite, the intensity of the Q band decreased, the B band upshifted to 46 degrees C but the C band disappeared. The suppression of the Q band and the upshift of the B band suggested that nitrite caused inhibition at the water oxidizing complex. The effects of nitrite also remained the same in the presence of chloride. In case of ion-sufficient thylakoid membranes, nitrite decreased the Q band peak intensity and caused an upshift in the B band peak temperature. Nitrite showed similar effects in the presence of DCMU. This suggested that the site of action of nitrite is not at the acceptor side but at the donor side of PS II. The inhibition shown by nitrite has been found to be specific for nitrite anion. No other anions such as formate, fluoride or nitrate, were effective.     

Structure prediction of dihydroflavonol 4- reductase and anthocyanidin synthase from spinach

Spinach is an important dietary vegetable associated with beneficial health effects. Flavonoids have various biological activities such as antioxidant, antibacterial, and anticancer effect Flavonoid including anthocyanin provides brilliant and colored pigments in different plant tissues. Anthocyanidin synthase and dihydroflavonol 4-reductase are responsible for anthocyanin biosynthesis. They contributed in plant protection against UV-B radiation, microbial and herbivore pathogens. A 3D structures of anthocyanidin synthase and dihydroflavonol 4-reductase from spinach are constructed in this study through homology modeling. The homology modeling is done by using the MODELLER 9v7 software. The energy of models was minimized by applying molecular mechanics method. The root mean square deviation (RMSD) for C atoms between the template and the homology-modeled structures was estimated by CE program. The final models were assessed by PROCHECK and WHATCHECK which showed that the final refined models are reliable.     

Mitochondrial β‐oxidation regulates organellar integrity and is necessary for conidial germination and invasive growth in Magnaporthe oryzae

Fatty acids stored as triglycerides, an important source of cellular energy, are catabolized through β‐oxidation pathways predicted to occur both in peroxisomes and mitochondria in filamentous fungi. Here, we characterize the function of Enoyl‐CoA hydratase Ech1, a mitochondrial β‐oxidation enzyme, in the model phytopathogen Magnaporthe oryzae. Ech1 was found to be essential for conidial germination and viability of older hyphae. Unlike wild‐type Magnaporthe, the ech1Δ failed to utilize C14 fatty acid and was partially impeded in growth on C16 and C18 fatty acids. Surprisingly, loss of β‐oxidation led to significantly altered mitochondrial morphology and integrity with ech1Δ showing predominantly vesicular/punctate mitochondria in contrast to the fused tubular network in wild‐type Magnaporthe. The ech1Δ appressoria were aberrant and displayed reduced melanization. Importantly, we show that the significantly reduced ability of ech1Δ to penetrate the host and establish therein is a direct consequence of enhanced sensitivity of the mutant to oxidative stress, as the defects could be remarkably reversed through exogenous antioxidants. Overall, our comparative analyses reveal that peroxisomal lipid catabolism is essential for appressorial function of host penetration, whereas mitochondrial β‐oxidation primarily contributes to conidial viability and maintenance of redox homeostasis during host colonization by Magnaporthe.     

Biological pretreatment of sugarcane trash for its conversion to fermentable sugars

Pretreatment of lignocellulosic biomasses, the first step in their conversion to utilizable molecules requires very high energy (steam and electricity), corrosion resistant high-pressure reactors and high temperatures. These severe conditions not only add to the cost component of the entire process but also lead to the loss of sugars to the side reactions. Microbial pretreatments have been reported to be associated with reducing the cost factors as well as the severities of the reactions. Eight bioagents, including fungi and bacteria, were screened for their pretreatment effects on sugarcane trash. They narrowed down the C:N ratio of trash from 108:1 to a varying range of approximately 42:1 to 60:1.The maximum drop in C:N ratio of 61% was observed using Aspergillus terreus followed by Cellulomonas uda (52%) and Trichoderma reesei and Zymomonas mobilis (49%). The bioagents helped in degradation of sugarcane trash by production of cellulases, the maximum being produced by A. terreus, (12 fold) followed by C. uda (10 fold), Cellulomonas cartae (9 fold) and Bacillus macerans (8 fold). The microbial pretreatment of trash rendered the easy accessibility of sugars for enzymatic hydrolysis, which can be directed for production of alcohol.     

Heat Shock Tolerant Mutants of Rhizobium meliloti Forming Ineffective Nodules

Six heat shock tolerant mutants of Rhizobium meliloti Rmd201 were isolated through transposon Tn5 mutagenesis. The symbiotic assays of these mutants with alfalfa plants, showed four of these mutants to be affected in nitrogenase effectivity also. These four mutants could be classified into two separate complementation groups hssA and hssC through R-prime mediated merodiploid constructions. The hssC mutant Rmd1040 also showed poor interaction with phages indicating surface alterations. The results indicated possible involvement of these loci in symbiosis as well as heat shock response.     

Minerals solubilizing and mobilizing microbiomes: A sustainable approach for managing minerals’ deficiency in agricultural soil

Agriculture faces challenges to fulfil the rising food demand due to shortage of arable land and various environmental stressors. Traditional farming technologies help in fulfilling food demand but they are harmful to humans and environmental sustainability. The food production along with agro-environmental sustainability could be achieved by encouraging farmers to use agro-environmental sustainable products such as biofertilizers and biopesticides consisting of live microbes or plant extract instead of chemical-based inputs. The eco-friendly formulations play a significant role in plant growth promotion, crop yield and repairing degraded soil texture and fertility sustainably. Mineral solubilizing microbes that provide vital nutrients like phosphorus, potassium, zinc and selenium are essential for plant growth and development and could be developed as biofertilizers. These microbes could be plant associated (rhizospheric, endophytic and phyllospheric) or inhabit the bulk soil and diverse extreme habitats. Mineral solubilizing microbes from soil, extreme environments, surface and internal parts of the plant belong to diverse phyla such as Ascomycota, Actinobacteria, Basidiomycota, Bacteroidetes, Chlorobi, Cyanobacteria, Chlorophyta, Euryarchaeota, Firmicutes, Gemmatimonadetes, Mucoromycota, Proteobacteria and Tenericutes. Mineral solubilizing microbes (MSMs) directly or indirectly stimulate plant growth and development either by releasing plant growth regulators; solubilizing phosphorus, potassium, zinc, selenium and silicon; biological nitrogen fixation and production of siderophores, ammonia, hydrogen cyanide, hydrolytic enzymes and bioactive compound/secondary metabolites. Biofertilizer developed using mineral solubilizing microbes is an eco-friendly solution to the sustainable food production system in many countries worldwide. The present review deals with the biodiversity of mineral solubilizing microbes, and potential roles in crop improvement and soil well-being for agricultural sustainability.