Melatonin in the regulation of annual testicular events in carp Catla catla: evidence from the studies on the effects of exogenous melatonin, continuous light, and continuous darkness

The physiological significance of melatonin in the regulation of annual testicular events in a major carp Catla catla was evaluated through studies on the effects of graded dose (25, 50, or 100 µg/100 g body wt.) of melatonin exogenously administered for different durations (1, 15, or 30 days) and manipulation of the endogenous melatonin system by exposing the fish to constant darkness (DD) or constant light (LL) for 30 days. An identical experimental schedule was followed during the preparatory (February-March), pre-spawning (April-May), spawning (July-August), and post-spawning (September-October) phases of the annual cycle. Irrespective of the reproductive status of the carp, LL suppressed while DD increased the mid-day and mid-night values of melatonin compared to respective controls. Influences of exogenous melatonin varied in relation to the dose and duration of treatment and the reproductive status of the carp. However, testicular response to exogenous melatonin (at 100 µg, for 30 days) and DD in each reproductive phase was almost identical. Notably, precocious testicular maturation occurred in both DD and melatonin-injected fish during the preparatory phase and in LL carps during the pre-spawning phase. In contrast, testicular functions in both the melatonin-treated and DD fish were inhibited during the pre-spawning and spawning phases, while the testes did not respond to any treatment during the post-spawning phase. In conclusion, this study provided the first experimental evidence that melatonin plays a significant role in the regulation of annual testicular events in a sub-tropical surface-dwelling carp Catla catla, but the influence of this pineal hormone on the seasonal activity of testis varies in relation to the reproductive status of the concerned fish.     

Horizontal gene transfer in chromalveolates

Background  

Horizontal gene transfer (HGT), the non-genealogical transfer of genetic material between different organisms, is considered a potentially important mechanism of genome evolution in eukaryotes. Using phylogenomic analyses of expressed sequence tag (EST) data generated from a clonal cell line of a free living dinoflagellate alga Karenia brevis, we investigated the impact of HGT on genome evolution in unicellular chromalveolate protists.     

TFG clusters COPII‐coated transport carriers and promotes early secretory pathway organization

In mammalian cells, cargo‐laden secretory vesicles leave the endoplasmic reticulum (ER) en route to ER‐Golgi intermediate compartments (ERGIC) in a manner dependent on the COPII coat complex. We report here that COPII‐coated transport carriers traverse a submicron, TFG (Trk‐fused gene)‐enriched zone at the ER/ERGIC interface. The architecture of TFG complexes as determined by three‐dimensional electron microscopy reveals the formation of flexible, octameric cup‐like structures, which are able to self‐associate to generate larger polymers in vitro. In cells, loss of TFG function dramatically slows protein export from the ER and results in the accumulation of COPII‐coated carriers throughout the cytoplasm. Additionally, the tight association between ER and ERGIC membranes is lost in the absence of TFG. We propose that TFG functions at the ER/ERGIC interface to locally concentrate COPII‐coated transport carriers and link exit sites on the ER to ERGIC membranes. Our findings provide a new mechanism by which COPII‐coated carriers are retained near their site of formation to facilitate rapid fusion with neighboring ERGIC membranes upon uncoating, thereby promoting interorganellar cargo transport.     

Aphid-repellent pheromone E-β-farnesene is generated in transgenic Arabidopsis thaliana over-expressing farnesyl diphosphate synthase2

Background and Aims Plant-synthesized sesquiterpenes play a pivotal role in chemotactic interactions with insects. Biosynthesis of functionally diverse sesquiterpenes is dependent on the availability of a pool of the precursor farnesyldiphosphate (FDP). In Arabidopsis thaliana, FPS2, encoding cytosolic farnesyldiphosphate synthase, is implicated in the synthesis of cytosolic FDP, but it is not known whether enhanced levels of FDP have a commensurate effect on sesquiterpene-mediated defence responses. This study examined transgenic arabidopsis plants generated to over-express FPS2 in order to determine if any effects could be observed in the response of aphids, Myzus persicae.Methods Transgenic arabidopsis plants were generated to over-express FPS2 to produce FPS2 in either the cytosol or the chloroplasts. Morphochemical analyses of the transgenic plants were carried out to detremine growth responses of roots and shoots, and for GC-MS profiling of sesquiterpenes. Aphid response to hyrdo-distillate extracts and head-space volatiles from transgenic plants was assessed using a bioassay.Key Results Either over-expression of FPS2 in the cytosol or targetting of its translated product to chlorplasts resulted in stimulatory growth responses of transgenic arabidopsis at early and late developmental stages. GC-MS analysis of hydro-distillate extracts from aerial parts of the plants revealed biosynthesis of several novel sesquiterpenes, including E-β-farnesene, an alarm pheromone of aphids. Both entrapped volatiles and hydro-distillate extracts of the transgenic leaves triggered agitation in aphids, which was related to both time and dose of exposure.Conclusions Over-expression of FPS2 in the cytosol and targeting of its translated product to chloroplasts in arabidopsis led to synthesis of several novel sesquiterpenes, including E-β-farnesene, and induced alarm responses in M. persicae. The results suggest a potential for engineering aphid-resistant strains of arabidopsis.     

The histone deacetylase inhibitor butyrate improves metabolism and reduces muscle atrophy during aging

Sarcopenia, the loss of skeletal muscle mass and function during aging, is a major contributor to disability and frailty in the elderly. Previous studies found a protective effect of reduced histone deacetylase activity in models of neurogenic muscle atrophy. Because loss of muscle mass during aging is associated with loss of motor neuron innervation, we investigated the potential for the histone deacetylase (HDAC) inhibitor butyrate to modulate age‐related muscle loss. Consistent with previous studies, we found significant loss of hindlimb muscle mass in 26‐month‐old C57Bl/6 female mice fed a control diet. Butyrate treatment starting at 16 months of age wholly or partially protected against muscle atrophy in hindlimb muscles. Butyrate increased muscle fiber cross‐sectional area and prevented intramuscular fat accumulation in the old mice. In addition to the protective effect on muscle mass, butyrate reduced fat mass and improved glucose metabolism in 26‐month‐old mice as determined by a glucose tolerance test. Furthermore, butyrate increased markers of mitochondrial biogenesis in skeletal muscle and whole‐body oxygen consumption without affecting activity. The increase in mass in butyrate‐treated mice was not due to reduced ubiquitin‐mediated proteasomal degradation. However, butyrate reduced markers of oxidative stress and apoptosis and altered antioxidant enzyme activity. Our data is the first to show a beneficial effect of butyrate on muscle mass during aging and suggests HDACs contribute to age‐related muscle atrophy and may be effective targets for intervention in sarcopenia and age‐related metabolic disease.     

Experimental studies and mathematical modeling of an up-flow biofilm reactor treating mustard oil rich wastewater

Bioremediation of lipid-rich model wastewater was investigated in a packed bed biofilm reactor (anaerobic filter). A detailed study was conducted about the influence of fatty acid concentration on biomethanation of the high-fat liquid effluent of edible oil refineries. The biochemical methane potential (BMP) of the liquid waste was reported and maximum cumulative methane production at the exit of the reactor is estimated to be 785 ml CH₄ (STP)/(g VSS added). The effects of hydraulic retention time (HRT), organic loading rate (OLR) and bed porosity on the cold gas efficiency or energy efficiency of the bioconversion process were also investigated. Results revealed that the maximum cold gas efficiency of the process is 42% when the total organic load is 2.1 g COD/l at HRT of 3.33 days. Classical substrate uninhibited Monod model is used to generate the differential system equations which can predict the reactor behavior satisfactorily.     

Good to the bone: microbial community thrives within bone cavities of a bison carcass at Yellowstone National Park

The discovery of unanticipated microbial diversity in remote, often hostile environments has led to a greater appreciation of the complexity and richness of the natural world. Yellowstone National Park (YNP) has long been a focus of work on taxa that inhabit extreme environments. Here we report the finding of microbial flora that inhabit an unexpected niche: the cavities of bone remnants from a bison carcass in Norris Geyser Basin in YNP. Although bleached white on the surface, the bone cavities are bright green due to the presence of Stichococcus-like trebouxiophyte green algae. The cavities also harbour different fungi and bacteria. Stichococcus species are common lichen photobionts and the Thelebolales fungi present in the bone cavities have previously been found in association with animal remains. Scanning electron microscope analysis suggests the fungi and algae do not form lichen-like associations in the bone. Rather these taxa and the bacteria appear to be opportunists that have colonized an isolated oasis that provides nutrients and protection from desiccation and UV radiation.     

Prophylactic role of D-Saccharic acid-1,4-lactone in tertiary butyl hydroperoxide induced cytotoxicity and cell death of murine hepatocytes via mitochondria-dependent pathways

D-Saccharic acid 1,4-lactone (DSL) is a derivative of D-glucaric acid. It is a beta-glucuronidase inhibitor and possesses anticarcinogenic, detoxifying, and antioxidant properties. In the present study, the protective effects of DSL were investigated against tertiary butyl hydroperoxide (TBHP) induced cytotoxicity and cell death in vitro using murine hepatocytes. Exposure of TBHP caused a reduction in cell viability, enhanced the membrane leakage, and disturbed the intracellular antioxidant machineries in murine hepatocytes. Investigating the signaling mechanism of TBHP-induced cellular pathophysiology and protective action of DSL, we found that TBHP exposure disrupted mitochondrial membrane potential, facilitated cytochrome c release in the cytosol, and led to apoptotic cell death via mitochondria-dependent pathways. DSL counteracted these changes and maintained normalcy in hepatocytes. Combining, results suggest that DSL possesses the ability to ameliorate TBHP-induced oxidative insult, cytotoxicity, and apoptotic cell death probably due to its antioxidant activity and functioning via mitochondria-dependent pathways.     

Site-specific structural analysis of a yeast prion strain with species-specific seeding activity

Prion proteins misfold and aggregate into multiple infectious strain variants that possess unique abilities to overcome prion species barriers, yet the structural basis for the species-specific infectivities of prion strains is poorly understood. Therefore, we have investigated the site-specific structural properties of a promiscuous chimeric form of the yeast prion Sup35 from Saccharomyces cerevisiae and Candida albicans. The Sup35 chimera forms two strain variants, each of which selectively infect one species but not the other. Importantly, the N-terminal and middle domains of the Sup35 chimera (collectively referred to as Sup35NM) contain two prion recognition elements (one from each species) that regulate the nucleation of each strain. Mutations in either prion recognition element significantly bias nucleation of one strain conformation relative to the other. Here we have investigated the folding of each prion recognition element for the serine-to-arginine mutant at residue 17 of the Sup35NM chimera known to promote nucleation of C. albicans strain conformation. Using cysteine-specific labeling analysis, we find that residues in the C. albicans prion recognition element are solvent-shielded, while those outside the recognition sequence (including most of those in the S. cerevisiae recognition element) are solvent-exposed. Moreover, we find that proline mutations in the C. albicans recognition sequence disrupt the prion templating activity of this strain conformation. Our structural findings reveal that differential folding of complementary and non-complementary prion recognition elements within the prion amyloid core of the Sup35NM chimera is the structural basis for its species-specific templating activity.Key words: Sup35, amyloid, fibril, PrP, transmission barrier, species barrier