Phylogenetic diversity of Mesorhizobium in chickpea

Crop domestication, in general, has reduced genetic diversity in cultivated gene pool of chickpea (Cicer arietinum) as compared with wild species (C. reticulatum, C. bijugum). To explore impact of domestication on symbiosis, 10 accessions of chickpeas, including 4 accessions of C. arietinum, and 3 accessions of each of C. reticulatum and C. bijugum species, were selected and DNAs were extracted from their nodules. To distinguish chickpea symbiont, preliminary sequences analysis was attempted with 9 genes (16S rRNA, atpD, dnaJ, glnA, gyrB, nifH, nifK, nodD and recA) of which 3 genes (gyrB, nifK and nodD) were selected based on sufficient sequence diversity for further phylogenetic analysis. Phylogenetic analysis and sequence diversity for 3 genes demonstrated that sequences from C. reticulatum were more diverse. Nodule occupancy by dominant symbiont also indicated that C. reticulatum (60%) could have more various symbionts than cultivated chickpea (80%). The study demonstrated that wild chickpeas (C. reticulatum) could be used for selecting more diverse symbionts in the field conditions and it implies that chickpea domestication affected symbiosis negatively in addition to reducing genetic diversity.     

Does Iris Change Over Time?

Iris as a biometric identifier is assumed to be stable over a period of time. However, some researchers have observed that for long time lapse, the genuine match score distribution shifts towards the impostor score distribution and the performance of iris recognition reduces. The main purpose of this study is to determine if the shift in genuine scores can be attributed to aging or not. The experiments are performed on the two publicly available iris aging databases namely, ND-Iris-Template-Aging-2008–2010 and ND-TimeLapseIris-2012 using a commercial matcher, VeriEye. While existing results are correct about increase in false rejection over time, we observe that it is primarily due to the presence of other covariates such as blur, noise, occlusion, and pupil dilation. This claim is substantiated with quality score comparison of the gallery and probe pairs.     

Equilibrium and kinetic studies of protein cooperativity using urea-induced folding/unfolding of a Ubq-UIM fusion protein

Understanding the origins of cooperativity in proteins remains an important topic in protein folding. This study describes experimental folding/unfolding equilibrium and kinetic studies of the engineered protein Ubq-UIM, consisting of ubiquitin (Ubq) fused to the sequence of the ubiquitin interacting motif (UIM) via a short linker. Urea-induced folding/unfolding profiles of Ubq-UIM were monitored by far-UV circular dichroism and fluorescence spectroscopies and compared to those of the isolated Ubq domain. It was found that the equilibrium data for Ubq-UIM is inconsistent with a two-state model. Analysis of the kinetics of folding shows similarity in the folding transition state ensemble between Ubq and Ubq-UIM, suggesting that formation of Ubq domain is independent of UIM. The major contribution to the stabilization of Ubq-UIM, relative to Ubq, was found to be in the rates of unfolding. Moreover, it was found that the kinetic m-values for Ubq-UIM unfolding, monitored by different probes (far-UV circular dichroism and fluorescence spectroscopies), are different; thereby, further supporting deviations from a two-state behavior. A thermodynamic linkage model that involves four states was found to be applicable to the urea-induced unfolding of Ubq-UIM, which is in agreement with the previous temperature-induced unfolding study. The applicability of the model was further supported by site-directed variants of Ubq-UIM that have altered stabilities of Ubq/UIM interface and/or stabilities of individual Ubq- and UIM-domains. All variants show increased cooperativity and one variant, E43N_Ubq-UIM, appears to behave very close to an equilibrium two-state.     

Transgenic potato overproducing L-ascorbic acid resisted an increase in methylglyoxal under salinity stress via maintaining higher reduced glutathione level and glyoxalase enzyme activity

Salt-tolerance was studied in transgenic potato. It was conferred by overexpression of ascorbate pathway enzyme (d-galacturonic acid reductase, GalUR). As genetic engineering of the GalUR gene in potato enhances its ascorbic acid content (l-AsA), and subsequently plants suffered minimal oxidative stress-induced damage, we now report on the comprehensive aptness of this engineering approach for enhanced salt tolerance in transgenic potato (Solanum tuberosum L. cv. Taedong Valley). Potatoes overexpressing GalUR grew and tuberized in continuous presence of 200 mM of NaCl. The transgenic plants maintained a higher reduced to oxidized glutathione (GSH:GSSG) ratio together with enhanced activity of glutathione dependent antioxidative and glyoxalase enzymes under salinity stress. The transgenics resisted an increase in methylglyoxal that increased radically in untransformed control plants under salinity stress. This is the first report of genetic engineering of ascorbate pathway gene in maintaining higher level of GSH homeostasis along with higher glyoxalase activity inhibiting the accumulation in methylglyoxal (a potent cytotoxic compound) under salt stress. These results suggested the engineering of ascorbate pathway enzymes as a major step towards developing salinity tolerant crop plants.     

Contribution of Ih to LTP, place cells, and grid cells

The brain's grid and place cells, which contribute to spatial representations of the external environment, are thought to be modulated by the hyperpolarization-activated cation current (I(h)). Giocomo et al. and Hussaini et al. now provide new insights into these cells' unique activity patterns by studying transgenic mice lacking I(h).     

Chronic melatonin administration mitigates behavioral dysfunction induced by γ-irradiation

Melatonin, a ‘hormone of darkness,’ has been reported to play a role in a wide variety of physiological responses including reproduction, circadian homeostasis, sleep, retinal neuromodulation, and vasomotor responses. Our recent studies reported a prophylactic effect of exogenous melatonin against radiation-induced neurocognitive changes. However, there is no reported evidence for a mitigating effect of chronic melatonin administration against radiation-induced behavioral alterations. In the present study, C57BL/6 mice were given either whole day chronic melatonin administration (CMA) or chronic night-time melatonin administration (CNMA) by a low dose of melatonin in drinking water for a period of 2 weeks and 1 month following exposure to 6 Gy of γ-radiation. Various behavioral endpoints, such as locomotor activities, gross behavioral traits, basal anxiety level, and depressive tendencies were scored at different time points. Radiation exposure significantly impaired gross behavioral traits as observed in the open field exploratory paradigms and forced swim test. Both the CMA and CNMA significantly ameliorated the radiation-induced changes in exploratory tendencies, risk-taking behavior and gross behavior traits, such as rearing and grooming. Melatonin administration afforded anxiolytic function against radiation in terms of center exploration tendencies. The radiation-induced augmentation of immobility time in the forced swim test, indices of depression-like behavior was also inhibited by chronic melatonin administration. The results demonstrated the mitigating effect of chronic melatonin administration on radiation-induced affective disorders in mice.     

The role of MOF in the ionizing radiation response is conserved in Drosophila melanogaster

In Drosophila, males absent on the first (MOF) acetylates histone H4 at lysine 16 (H4K16ac). This acetylation mark is highly enriched on the male X chromosome and is required for dosage compensation in Drosophila but not utilized for such in mammals. Recently, we and others reported that mammalian MOF, through H4K16ac, has a critical role at multiple stages in the DNA damage response (DDR) and double-strand break repair pathways. The goal of this study was to test whether mof is similarly required for the response to ionizing radiation (IR) in Drosophila. We report that Drosophila mof mutations in males and females, as well as mof knockdown in SL-2 cells, reduce post-irradiation survival. MOF depletion in SL-2 cells also results in an elevated frequency of metaphases with chromosomal aberrations, suggesting that MOF is involved in DDR. Mutation in Drosophila mof also results in a defective mitotic checkpoint, enhanced apoptosis, and a defective p53 response post-irradiation. In addition, IR exposure enhanced H4K16ac levels in Drosophila as it also does in mammals. These results are the first to demonstrate a requirement for MOF in the whole animal IR response and suggest that the role of MOF in the response to IR is conserved between Drosophila and mammals.