Genotypic differences in water status,membrane integrity,ionic content,N2-fixing efficiency and dry matter of mungbean nodules under saline irrigation

A pot experiment was conducted under natural conditions of screen house to evaluate the effect of saline irrigation given at flowering stage (30–35 DAS) on nodule functioning and their tolerance in two mungbean genotypes viz. Asha and Muskan based on various physiological traits. The pots containing sandy soil (Typic Torrispamments) were saturated with Cl-dominated saline irrigation to maintain ECe of 2.5, 5.0, 7.5 dS m⁻¹ as compared to control. In both the genotypes osmotic potential (Ψs) and relative water content (RWC %) of nodules decreased significantly, while a sharp rise in proline and total soluble sugars contents were observed with the increasing level of saline irrigation after 10 and 20 days of treatment. A marked increase in hydrogen peroxide (H₂O₂), lipid peroxidation (MDA content) and relative stress injury (RSI %) was noticed in nodules which were much higher in Muskan. The decrease in Ψs of nodules was more pronounced in Asha than in Muskan, while reverse was true for RWC and proline accumulation. A sharp decline in acetylene reduction assay (ARA) for N₂-fixation, leghemoglobin content and dry matter of the nodules was observed, but was more in Muskan than in Asha. Nitrogen (N) content declined while Na⁺/K⁺ ratio and Cl⁻ content increased significantly. The genotype Asha maintained better N₂-fixing efficiency but lower Na⁺/K⁺ ratio and Cl⁻ content in nodules than Muskan. Though the nodule functioning was further deteriorated at 20 DAT in both the genotypes yet the tolerance capacity of nodules in Asha was better than in Muskan under saline conditions which is correlated with the compensatory mechanism i.e. osmoregulation in nodules.Key words: Leghemoglobin, Lipid peroxidation, Minerals, N₂-ase activity, Vigna radiata, Water relations     

Cyclooxygenase-2 dependent metabolism of 20-HETE increases adiposity and adipocyte enlargement in mesenchymal stem cell-derived adipocytes

20-Hydroxy-5,8,11,14-eicosatetraenoic acid (20-HETE), a product of the cytochrome P450 (CYP)-catalyzed ω-hydroxylation of arachidonic acid, induces oxidative stress and, in clinical studies, is associated with increased body mass index (BMI) and the metabolic syndrome. This study was designed to examine the effects of exogenous 20-HETE on mesenchymal stem cell (MSC)-derived adipocytes. The expression levels of CYP4A11 and CYP4F2 (major 20-HETE synthases in humans) in MSCs decreased during adipocyte differentiation; however, exogenous administration of 20-HETE (0.1–1 μM) increased adipogenesis in a dose-dependent manner in these cells (P < 0.05). The inability of a 20-HETE analog to reproduce these effects suggested the involvement of a metabolic product of 20-HETE in mediating its pro-adipogenic effects. A cyclooxygenase (COX)-1 selective inhibitor enhanced, whereas a COX-2 selective or a dual COX-1/2 inhibitor attenuated adipogenesis induced by 20-HETE. The COX-derived metabolite of 20-HETE, 20-OH-PGE₂, enhanced adipogenesis and lipid accumulation in MSCs. The pro-adipogenic effects of 20-HETE and 20-OH-PGE₂ resulted in the increased expression of the adipogenic regulators PPARγ and β-catenin in MSC-derived adipocytes. Taken together we show for the first time that 20-HETE-derived COX-2-dependent 20-OH-PGE₂ enhances mature inflamed adipocyte hypertrophy in MSC undergoing adipogenic differentiation.     

Clostridium perfringens epsilon toxin H149A mutant as a platform for receptor binding studies

Clostridium perfringens epsilon toxin (Etx) is a pore‐forming toxin responsible for a severe and rapidly fatal enterotoxemia of ruminants. The toxin is classified as a category B bioterrorism agent by the U.S. Government Centres for Disease Control and Prevention (CDC), making work with recombinant toxin difficult. To reduce the hazard posed by work with recombinant Etx, we have used a variant of Etx that contains a H149A mutation (Etx‐H149A), previously reported to have reduced, but not abolished, toxicity. The three‐dimensional structure of H149A prototoxin shows that the H149A mutation in domain III does not affect organisation of the putative receptor binding loops in domain I of the toxin. Surface exposed tyrosine residues in domain I of Etx‐H149A (Y16, Y20, Y29, Y30, Y36 and Y196) were mutated to alanine and mutants Y30A and Y196A showed significantly reduced binding to MDCK.2 cells relative to Etx‐H149A that correlated with their reduced cytotoxic activity. Thus, our study confirms the role of surface exposed tyrosine residues in domain I of Etx in binding to MDCK cells and the suitability of Etx‐H149A for further receptor binding studies. In contrast, binding of all of the tyrosine mutants to ACHN cells was similar to that of Etx‐H149A, suggesting that Etx can recognise different cell surface receptors. In support of this, the crystal structure of Etx‐H149A identified a glycan (β‐octyl‐glucoside) binding site in domain III of Etx‐H149A, which may be a second receptor binding site. These findings have important implications for developing strategies designed to neutralise toxin activity.     

High-fat diet exacerbates renal dysfunction in SHR: reversal by induction of HO-1-adiponectin axis

High-dietary fat intake is a major risk factor for development of metabolic and cardiovascular-renal dysfunction including obesity, coronary artery disease, hypertension, and chronic renal failure. We examined the effect of a high-fat diet on renal function and morphology in spontaneously hypertensive rats (SHR), a phenotype designed to mimic metabolic syndrome. High-fat diet induced increase (P < 0.05) in blood pressure, body weight, and renal lipid deposition in these rats. This increase in body weight was accompanied by elevations (P < 0.05) of blood glucose and low-density lipoprotein (LDL) levels, a decrease (P < 0.05) in adiponectin and increases (P < 0.05) in plasma monocyte chemotactic protein-1 (MCP-1) along with renal macrophage infiltration. These pathophysiological perturbations were attenuated (P < 0.05) by heme oxygenase-1 (HO-1) induction by treatment with cobalt protoporphyrin (CoPP). Further effects of CoPP included increased (P < 0.05) renal expression of adiponectin along with enhancement (P < 0.05) of pAKT, pAMPK, and p-eNOS in SHRs fed a high-fat diet. Prevention of such beneficial effects of CoPP by the concurrent administration of the heme-HO inhibitor stannous mesoporphyrin (SnMP) corroborates the role of HO system in mediating such effects. Taken together, our results demonstrate that high-fat diet induces a metabolic syndrome-like phenotype in hypertensive rats, which is amenable to rescue by increases in HO-1- and adiponectin-dependent pathways.     

On generalized Simes critical constants

We consider the problem treated by Simes of testing the overall null hypothesis formed by the intersection of a set of elementary null hypotheses based on ordered p‐values of the associated test statistics. The Simes test uses critical constants that do not need tabulation. Cai and Sarkar gave a method to compute generalized Simes critical constants which improve upon the power of the Simes test when more than a few hypotheses are false. The Simes constants can be viewed as the first order (requiring solution of a linear equation) and the Cai‐Sarkar constants as the second order (requiring solution of a quadratic equation) constants. We extend the method to third order (requiring solution of a cubic equation) constants, and also offer an extension to an arbitrary kth order. We show by simulation that the third order constants are more powerful than the second order constants for testing the overall null hypothesis in most cases. However, there are some drawbacks associated with these higher order constants especially for , which limits their practical usefulness.     

The state and conservation of Southeast Asian biodiversity

Southeast Asia is a region of conservation concern due to heavy losses of its native habitats. In this overview, we highlight the conservation importance of Southeast Asia by comparing its degree of species endemism and endangerment, and its rate of deforestation with other tropical regions (i.e., Meso-America, South America, and Sub-Saharan Africa). Southeast Asia contains the highest mean proportion of country-endemic bird (9%) and mammal species (11%). This region also has the highest proportion of threatened vascular plant, reptile, bird, and mammal species. Furthermore, not only is Southeast Asia’s annual deforestation rate the highest in the tropics, but it has also increased between the periods 1990–2000 and 2000–2005. This could result in projected losses of 13–85% of biodiversity in the region by 2100. Secondary habitat restoration, at least in certain countries, would allow for some amelioration of biodiversity loss and thus potentially lower the currently predicted extinction rates. Nonetheless, urgent conservation actions are needed. Conservation initiatives should include public education, sustaining livelihoods, and ways to enhance the sustainability of agriculture and increase the capacity of conservation institutions. Furthermore, these actions should be country-specific and not ignore areas heavily populated by humans, as they can also harbour high numbers of threatened species. We urge that cooperative conservation initiatives be undertaken and support (e.g., capacity-building) be given by more developed countries in the region and beyond.