The rice <Emphasis Type="Italic">OsSAG12-2</Emphasis> gene codes for a functional protease that negatively regulates stress-induced cell death

Senescence is the final stage of plant development. Although expression of most of the genes is suppressed during senescence, a set of genes referred as senescence-associated genes (SAGs) is induced. Arabidopsis thaliana SAG12 (AtSAG12) is one such gene that has been mostly studied for its strict association with senescence. AtSAG12 encodes a papain-like cysteine protease, expressed predominantly in senescence-associated vacuoles. Rice genome contains multiple AtSAG12 homologues (OsSAGs). OsSAG12-1, the closest structural homologue of AtSAG12, is a negative regulator of developmental and stress-induced cell death. Proteolytic activity has not been established for any SAG12 homologues in vitro. Here, we report that OsSAG12-2, the second structural homologue of AtSAG12 from rice, codes for a functional proteolytic enzyme. The recombinant OsSAG12-2 protein produced in Escherichia coli undergoes autolysis to generate a functional protease. The matured OsSAG12-2 protein shows 27% trypsin-equivalent proteolytic activity on azocasein substrate. Dark-induced senescence activates OsSAG12-2 expression. Down-regulation of OsSAG12-2 in the transgenic artificial miRNA lines results in enhanced salt- and UV-induced cell death, even though it does not affect cell viability in the stress-free condition. Our results show that OsSAG12-2 codes for a functional protease that negatively regulates stress-induced cell death in rice.     

Desiccation stress induces developmental heterochrony in <Emphasis Type="Italic">Drosophila melanogaster</Emphasis>

Stressful environments are known to perturb developmental patterns in insects. In the purview of desiccation as a stressor, relatively little is known about the developmental consequences linked with desiccation tolerance. In this study, we have particularly focused on the exploration of the temporal profile of postembryonic development in response to desiccation exposure in Drosophila melanogaster and the associated trade-offs. We document a correlation between variations in 20-hydroxyecdysone levels and the altered timing of metamorphic events during the life cycle. Following desiccation, we observed an extension in the larval longevity whereas the duration of the pupal and adult stages was significantly shortened. Alternately, feeding of 20-hydroxyecdysone apparently led to the restoration of the normal temporal pattern of development in the desiccated group. In spite of the desiccation-responsive heterochronic shifts in development, the overall lifespan post recovery remained almost unaltered among the desiccated and undesiccated groups suggesting plasticity in developmental control. This observation reminisces ‘canalization-like’ phenomenon that buffers alterations in the overall lifespan. We thus identified a desiccation-responsive period in the lifespan of D. melanogaster during which variations in ecdysone levels are capable to alter the temporal course of development.     

Heterochromatin and the molecular mechanisms of ‘parent-of-origin’ effects in animals

Twenty five years ago it was proposed that conserved components of constitutive heterochromatin assemble heterochromatin-like complexes in euchromatin and this could provide a general mechanism for regulating heritable (cell-to-cell) changes in gene expressibility. As a special case, differences in the assembly of heterochromatin-like complexes on homologous chromosomes might also regulate the parent-of-origin-dependent gene expression observed in placental mammals. Here, the progress made in the intervening period with emphasis on the role of heterochromatin and heterochromatin-like complexes in parent-of-origin effects in animals is reviewed.     

Galectin-9: From cell biology to complex disease dynamics

Galectins is a family of non-classically secreted, β-galactoside-binding proteins that has recently received considerable attention in the spatio-temporal regulation of surface ‘signal lattice’ organization, membrane dynamics, cell-adhesion and disease therapeutics. Galectin-9 is a unique member of this family, with two non-homologous carbohydrate recognition domains joined by a linker peptide sequence of variable lengths, generating isoforms with distinct properties and functions in both physiological and pathological settings, such as during development, immune reaction, neoplastic transformations and metastasis. In this review, we summarize the latest knowledge on the structure, receptors, cellular targets, trafficking pathways and functional properties of galectin-9 and discuss how galectin-9-mediated signalling cascades can be exploited in cancers and immunotherapies.     

Brain-derived neurotrophic factor and early-life stress: Multifaceted interplay

The brain-derived neurotrophic factor (BDNF) is a key regulator of neural development and plasticity. Long-term changes in the BDNF pathway are associated with childhood adversity and adult depression symptoms. Initially, stress-induced decreases in the BDNF pathway were found in some studies, but subsequent reports indicated the relationship between stress and BDNF to be much more complex, and the concept was significantly revised. In the present mini-review, we focus on the structure and regulation of the Bbnf gene as well as on the stress–BDNF interactions under early-life adverse conditions.     

Bifunctional recombinant cellulase–xylanase (rBhcell-xyl) from the polyextremophilic bacterium <Emphasis Type="Italic">Bacillus halodurans</Emphasis> TSLV1 and its utility in valorization of renewable agro-residues

The thermostable bifunctional CMCase and xylanase encoding gene (rBhcell-xyl) from Bacillus halodurans TSLV1 has been expressed in Escherichia coli. The recombinant E. coli produced rBhcell-xyl (CMCase 2272 and 910 U L^?1 xylanase). The rBhcell-xyl is a ~62-kDa monomeric protein with temperature and pH optima of 60 °C and 6.0 with T_1/2 of 7.0 and 3.5 h at 80 °C for CMCase and xylanase, respectively. The apparent K _m values (CMC and Birchwood xylan) are 3.8 and 3.2 mg mL^?1. The catalytic efficiency (k _cat/K _m ) values of xylanase and CMCase are 657 and 171 mL mg^?1 min^?1, respectively. End-product analysis confirmed that rBhcell-xyl is a unique endo-acting enzyme with exoglucanase activity. The rBhcell-xyl is a GH5 family enzyme possessing single catalytic module and carbohydrate binding module. The action of rBhcell-xyl on corn cobs and wheat bran liberated reducing sugars, which can be fermented to bioethanol and fine biochemicals.