The Ino80 chromatin-remodeling complex restores chromatin structure during UV DNA damage repair

Chromatin structure is modulated during deoxyribonucleic acid excision repair, but how this is achieved is unclear. Loss of the yeast Ino80 chromatin-remodeling complex (Ino80-C) moderately sensitizes cells to ultraviolet (UV) light. In this paper, we show that INO80 acts in the same genetic pathway as nucleotide excision repair (NER) and that the Ino80-C contributes to efficient UV photoproduct removal in a region of high nucleosome occupancy. Moreover, Ino80 interacts with the early NER damage recognition complex Rad4-Rad23 and is recruited to chromatin by Rad4 in a UV damage-dependent manner. Using a modified chromatin immunoprecipitation assay, we find that chromatin disruption during UV lesion repair is normal, whereas the restoration of nucleosome structure is defective in ino80 mutant cells. Collectively, our work suggests that Ino80 is recruited to sites of UV lesion repair through interactions with the NER apparatus and is required for the restoration of chromatin structure after repair.     

Effects of damming on population sustainability of Chinese sturgeon, <Emphasis Type="Italic">Acipenser sinensis</Emphasis>: evaluation of optimal conservation measures

The numbers of spawning sites for Chinese sturgeon have been drastically reduced since the construction of the Gezhouba Dam across the Yangtze River. This dam has blocked migration of Chinese sturgeon to their historic spawning ground causing a significant decline of the Chinese sturgeon population. We conducted a VORTEX population viability analysis to estimate the sustainability of the population and to quantify the efficiency of current and alternative conservation procedures. The model predicted the observed decline of Chinese sturgeon, resulting from the effect of the Gezhouba Dam. These simulations demonstrated the potential interest of two conservation measures: increasing spawning area and reducing predation on sturgeon eggs. The simulations also demonstrated that the actual restocking program is not sufficient to sustain sturgeon population as the artificial reproduction program induce the loss of more wild mature adults that the recruitment expected by the artificial reproduction.     

Life history of the riverine cyprinid Henicorhynchus siamensis (Sauvage, 1881) in a small reservoir

The riverine species, Henicorhynchus siamensis (Sauvage 1881), is an important source of protein and an economical fish for the rural population of inland Indochina. Investigated in the present study were the reproductive feeding aspects and growth of H. siamensis living in a lake system. The gonadosomatic index peaked in August, which was delayed compared to river fish, and individuals took 1.5 years to attain the length of 50% maturity (about 200 mm). Stomach contents were dominated by phytoplankton and showed considerable seasonal variation. Asymptotic length of H. siamensis was 264.2 mm, with a 0.75 year^?1 growth coefficient and slower growth during the winter. The role of the flood pulse as a major influence on the life history of the fish is also discussed.     

To what extent are the dietary compositions of three abundant,co‐occurring labrid species different and related to latitude,habitat, body size and season?

This study demonstrated that the dietary composition of each of three abundant reef-associated labrid species in temperate Western Australia differed significantly with latitude and changed with increasing body size and almost invariably differed among those species when they co-occurred. These results were derived from comparisons and multivariate analyses of volumetric dietary data, obtained from the foregut contents of Coris auricularis, Notolabrus parilus and Ophthalmolepis lineolatus from the Jurien Bay Marine Park (JBMP) and waters off Perth, 250 km to the south. Latitudinal differences in the dietary compositions of each species in exposed reefs typically reflected greater contributions by large crustaceans, bivalve molluscs, echinoids and annelids to the diets in the waters off Perth than in the JBMP, whereas the reverse was true for gastropods and small crustaceans. The diet of each species exhibited similar, but not identical, quantitative changes with increasing body size, with the contributions of small crustaceans declining and those of large crustaceans and echinoids increasing, while that of gastropods underwent little change. Within the JBMP, the dietary compositions of both C. auricularis and N. parilus were similar in exposed and sheltered reefs and the same was true for N. parilus in the sheltered reefs and interspersed areas of seagrass. The latter similarity demonstrated that, in both of those divergent habitat types, N. parilus feeds on prey associated with either the sand or the macrophytes that cover and lie between the reefs. Although the main dietary components of each species were the same, i.e. gastropods, small crustaceans (mainly amphipods and isopods), large crustaceans (particularly penaeids and brachyuran crabs) and echinoids, their contributions varied among those species, which accounts for the significant interspecific differences in diet. Coris auricularis had the most distinct diet, due mainly to an ingestion of greater volumes of small crustaceans, e.g. amphipods and isopods, and lesser volumes of large crustaceans, e.g. brachyuran crabs, which was associated with a relatively narrower mouth and smaller teeth and the absence of prominent canines at the rear of the jaw. The above intra and interspecific differences in dietary composition would reduce, on the south-west coast of Australia, the potential for competition for food among and within these three abundant labrids, each of which belongs to different genera within the Julidine clade.     

Lysosomal positioning coordinates cellular nutrient responses

mTOR (mammalian target of rapamycin) signalling and macroautophagy (henceforth autophagy) regulate numerous pathological and physiological processes, including cellular responses to altered nutrient levels. However, the mechanisms regulating mTOR and autophagy remain incompletely understood. Lysosomes are dynamic intracellular organelles intimately involved both in the activation of mTOR complex 1 (mTORC1) signalling and in degrading autophagic substrates. Here we report that lysosomal positioning coordinates anabolic and catabolic responses with changes in nutrient availability by orchestrating early plasma-membrane signalling events, mTORC1 signalling and autophagy. Activation of mTORC1 by nutrients correlates with its presence on peripheral lysosomes that are physically close to the upstream signalling modules, whereas starvation causes perinuclear clustering of lysosomes, driven by changes in intracellular pH. Lysosomal positioning regulates mTORC1 signalling, which in turn influences autophagosome formation. Lysosome positioning also influences autophagosome-lysosome fusion rates, and thus controls autophagic flux by acting at both the initiation and termination stages of the process. Our findings provide a physiological role for the dynamic state of lysosomal positioning in cells as a coordinator of mTORC1 signalling with autophagic flux.     

Mutations in BICD2 Cause Dominant Congenital Spinal Muscular Atrophy and Hereditary Spastic Paraplegia

Dominant congenital spinal muscular atrophy (DCSMA) is a disorder of developing anterior horn cells and shows lower-limb predominance and clinical overlap with hereditary spastic paraplegia (HSP), a lower-limb-predominant disorder of corticospinal motor neurons. We have identified four mutations in bicaudal D homolog 2 (Drosophila) (BICD2) in six kindreds affected by DCSMA, DCSMA with upper motor neuron features, or HSP. BICD2 encodes BICD2, a key adaptor protein that interacts with the dynein-dynactin motor complex, which facilitates trafficking of cellular cargos that are critical to motor neuron development and maintenance. We demonstrate that mutations resulting in amino acid substitutions in two binding regions of BICD2 increase its binding affinity for the cytoplasmic dynein-dynactin complex, which might result in the perturbation of BICD2-dynein-dynactin-mediated trafficking, and impair neurite outgrowth. These findings provide insight into the mechanism underlying both the static and the slowly progressive clinical features and the motor neuron pathology that characterize BICD2-associated diseases, and underscore the importance of the dynein-dynactin transport pathway in the development and survival of both lower and upper motor neurons.