Interbasin water transfer, riverine connectivity, and spatial controls on fish biodiversity

Background

Large-scale inter-basin water transfer (IBWT) projects are commonly proposed as solutions to water distribution and supply problems. These problems are likely to intensify under future population growth and climate change scenarios. Scarce data on the distribution of freshwater fishes frequently limits the ability to assess the potential implications of an IBWT project on freshwater fish communities. Because connectivity in habitat networks is expected to be critical to species'' biogeography, consideration of changes in the relative isolation of riverine networks may provide a strategy for controlling impacts of IBWTs on freshwater fish communities.

Methods/Principal Findings

Using empirical data on the current patterns of freshwater fish biodiversity for rivers of peninsular India, we show here how the spatial changes alone under an archetypal IBWT project will (1) reduce freshwater fish biodiversity system-wide, (2) alter patterns of local species richness, (3) expand distributions of widespread species throughout peninsular rivers, and (4) decrease community richness by increasing inter-basin similarity (a mechanism for the observed decrease in biodiversity). Given the complexity of the IBWT, many paths to partial or full completion of the project are possible. We evaluate two strategies for step-wise implementation of the 11 canals, based on economic or ecological considerations. We find that for each step in the project, the impacts on freshwater fish communities are sensitive to which canal is added to the network.

Conclusions/Significance

Importantly, ecological impacts can be reduced by associating the sequence in which canals are added to characteristics of the links, except for the case when all 11 canals are implemented simultaneously (at which point the sequence of canal addition is inconsequential). By identifying the fundamental relationship between the geometry of riverine networks and freshwater fish biodiversity, our results will aid in assessing impacts of IBWT projects and balancing ecosystem and societal demands for freshwater, even in cases where biodiversity data are limited.     

Identification of human proteins that modify misfolding and proteotoxicity of pathogenic ataxin-1

Proteins with long, pathogenic polyglutamine (polyQ) sequences have an enhanced propensity to spontaneously misfold and self-assemble into insoluble protein aggregates. Here, we have identified 21 human proteins that influence polyQ-induced ataxin-1 misfolding and proteotoxicity in cell model systems. By analyzing the protein sequences of these modifiers, we discovered a recurrent presence of coiled-coil (CC) domains in ataxin-1 toxicity enhancers, while such domains were not present in suppressors. This suggests that CC domains contribute to the aggregation- and toxicity-promoting effects of modifiers in mammalian cells. We found that the ataxin-1-interacting protein MED15, computationally predicted to possess an N-terminal CC domain, enhances spontaneous ataxin-1 aggregation in cell-based assays, while no such effect was observed with the truncated protein MED15ΔCC, lacking such a domain. Studies with recombinant proteins confirmed these results and demonstrated that the N-terminal CC domain of MED15 (MED15CC) per se is sufficient to promote spontaneous ataxin-1 aggregation in vitro. Moreover, we observed that a hybrid Pum1 protein harboring the MED15CC domain promotes ataxin-1 aggregation in cell model systems. In strong contrast, wild-type Pum1 lacking a CC domain did not stimulate ataxin-1 polymerization. These results suggest that proteins with CC domains are potent enhancers of polyQ-mediated protein misfolding and aggregation in vitro and in vivo.     

Molecular phylogeny of the cyprinid tribe Labeonini (Teleostei: Cypriniformes)

The cyprinid tribe Labeonini (sensuRainboth, 1991) is a large group of freshwater fishes containing around 40 genera and 400 species. They are characterized by an amazing diversity of modifications to their lips and associated structures. In this study, a total of 34 genera and 142 species of putative members of this tribe, which represent most of the generic diversity and more than one third of the species diversity of the group, were sampled and sequenced for four nuclear genes and five mitochondrial genes (totaling 9465bp). Phylogenetic relationships and subdivision of this tribe were investigated and the placement and status of most genera are discussed. Partitioned maximum likelihood analyses were performed based on the nuclear dataset, mitochondrial dataset, combined dataset, and the dataset for each nuclear gene. Inclusion of the genera Paracrossochilus, Barbichthys, Thynnichthys, and Linichthys in the Labeonini was either confirmed or proposed for the first time. None of the genera Labeo, Garra, Bangana, Cirrhinus, and Crossocheilus are monophyletic. Taxonomic revisions of some genera were made: the generic names Gymnostomus Heckel, 1843, Ageneiogarra Garman, 1912 and Gonorhynchus McClelland, 1839 were revalidated; Akrokolioplax Zhang and Kottelat, 2006 becomes a junior synonym of Gonorhynchus; the species Osteochilus nashii was found to be a member of the barbin genus Osteochilichthys. Five historical hypotheses on the classification of the Labeonini were tested and rejected. We proposed to subdivide the tribe, which is strongly supported as monophyletic, into four subtribes: Labeoina, Garraina, Osteochilina, and Semilabeoina. The taxa included in each subtribe were listed and those taxa that need taxonomic revision were discussed.     

Synergistic interactions of Ferulic acid with Ascorbic acid: Its cardioprotective role during isoproterenol induced myocardial infarction in rats

Studies on the lipid peroxidation and antioxidant changes and their significance during myocardial injury have provided a new insight into the pathogenesis of heart disease. The heart failure subsequent to myocardial infarction may be associated with an antioxidant deficit as well as increased myocardial oxidative stress. The present study was designed to evaluate the effect of the combination of ferulic acid and ascorbic acid on antioxidant defense system and lipid peroxidation against isoproterenol (ISO)-induced myocardial infarction in rats. Induction of rats with isoproterenol (150 mg/kg body weight daily, i.p.) for 2 days resulted in a marked elevation in lipid peroxidation, serum marker enzymes (LDH, CPK, GOT, and GPT), and a significant decrease in activities of endogenous antioxidants (SOD, GPx, GST, CAT, and GSH). Pre-co-treatment with the combination of ferulic acid (20 mg/kg body weight/day) and ascorbic acid (80 mg/kg body weight/day) orally for 6 days, significantly attenuated these changes when compared to the individual treatment groups. Histopathological observations were also in correlation with the biochemical parameters. Thus, ferulic acid and ascorbic acid significantly counteracted the pronounced oxidative stress effect of ISO by the inhibition of lipid peroxidation, restoration of antioxidant status, and myocardial marker enzymes levels. In conclusion, these findings indicate the synergistic protective effect of ferulic acid and ascorbic acid on lipid peroxidation and antioxidant defense system during ISO-induced myocardial infarction and associated oxidative stress in rats.     

Global gene expression profiling and cluster analysis in Xenopus laevis

We have undertaken a large-scale microarray gene expression analysis using cDNAs corresponding to 21,000 Xenopus laevis ESTs. mRNAs from 37 samples, including embryos and adult organs, were profiled. Cluster analysis of embryos of different stages was carried out and revealed expected affinities between gastrulae and neurulae, as well as between advanced neurulae and tadpoles, while egg and feeding larvae were clearly separated. Cluster analysis of adult organs showed some unexpected tissue-relatedness, e.g. kidney is more related to endodermal than to mesodermal tissues and the brain is separated from other neuroectodermal derivatives. Cluster analysis of genes revealed major phases of co-ordinate gene expression between egg and adult stages. During the maternal-early embryonic phase, genes maintaining a rapidly dividing cell state are predominantly expressed (cell cycle regulators, chromatin proteins). Genes involved in protein biosynthesis are progressively induced from mid-embryogenesis onwards. The larval-adult phase is characterised by expression of genes involved in metabolism and terminal differentiation. Thirteen potential synexpression groups were identified, which encompass components of diverse molecular processes or supra-molecular structures, including chromatin, RNA processing and nucleolar function, cell cycle, respiratory chain/Krebs cycle, protein biosynthesis, endoplasmic reticulum, vesicle transport, synaptic vesicle, microtubule, intermediate filament, epithelial proteins and collagen. Data filtering identified genes with potential stage-, region- and organ-specific expression. The dataset was assembled in the iChip microarray database, , which allows user-defined queries. The study provides insights into the higher order of vertebrate gene expression, identifies synexpression groups and marker genes, and makes predictions for the biological role of numerous uncharacterized genes.     

Optimal analytical conditions for catalase in fresh water prawn, Macrobrachium malcolmsonii

The cytosol of hepatopancreas was prepared from the freshwater prawn Macrobrachium malcolmsonii, and optimal assay conditions, i.e., concentration of substrate, pH, and temperature, were determined to measure basal activities and kinetic constants of catalase activity. The properties of catalase were examined in M. macolmsonii, because quantitative data on catalase are limited in crustacean species. The optimal pH for catalase was 7.0. The activation energy was 3.55 Kcal/mol and energy inhibition value was 5.16 Kcal/mol. The value of energy inhibition is higher than that of energy activation. This may be due to inhibition of catalase by some substrate other than H2O2. A Km of 66.6 mM was also determined from various concentrations of substrate.     

Ecosystem Restoration of Jhum Fallows in Northeast India: Microbial C and N Along Altitudinal and Successional Gradients

Abstract To characterize the altitudinal and successional trends in microbial biomass and to understand their role in soil nutrient dynamics during the aggradation phase (vegetation recovery) of abandoned shifting cultivation systems, we determined the soil properties and microbial C and N in jhum (slash‐and‐burn) cultivation systems at different altitudes and 1‐, 7‐, and 16‐year‐old fallow agricultural lands at lower and higher altitudes in the northeastern Indian hills. Density of ground vegetation was lower in the undisturbed forest than in the jhum fallows. In general, 1‐year jhum fallow had greater herbaceous vegetation both at lower and higher altitudes. Although woody plants were observed in 7‐ and 16‐year‐old jhum fallows, their density was highest in the forest. Soil moisture, organic C, and total N also increased gradually with increasing altitude and progressive secondary succession. Soil pH showed a negative correlation with altitude (as also confounded by soil type) and fallow age. Both microbial C and N had a close correlation with altitude and fallow age. Contribution of microbial C to soil organic C was 2.0–2.6% and microbial N to total N 1.4–2.2% in jhum fields, 2.4–4.3% and 1.2–2.1%, respectively, in jhum fallows, and 2.5–2.9% and 1.6–1.9% in the forests. Microbial C and N showed a negative correlation with herbaceous plant density. Microbial biomass in the jhum fallows and forest stands had a positive relationship with woody vegetation. Along an altitudinal and/or successional gradient, microbial C and N were positively correlated with water‐holding capacity, soil moisture, organic C, and total N and negatively correlated with soil pH. Microbial C and N were positively correlated with each other. Therefore, the study suggests that the altitudinal and successional dynamics of microbial C and N are linked to, among other properties, soil organic matter and total nitrogen contents in the soil during community development after land abandonment from shifting cultivation.     

A Study on the nature of genetic divergence in rice from assam and North East Himalayas

Summary A representative group of 190 rice types collected from North-East India along with four standard varieties, three of which were indicas and one japonica, was studied to understand the nature of genetic divergence. Preliminary grouping was done by canonical analysis and the resultant 42 groups were further classified using the D² statistic.The final grouping resulted in nine divergent clusters. The three indica standards were found in three different clusters indicating the wide available variability among them. The japonica standard formed a separate group by itself. A majority of the North-East Indian types formed clusters with indicas, whereas some were intermediate and still others were closer to japonica or indica, thus indicating a series of intergrades bridging indica and japonica.Height followed by leaf area was found to be important for primary and 100-grain weight, followed by amylose content for secondary differentiation. It appears that natural selection as well as human selection might have operated for characters differentiating rice types in Assam and North Eastern Himalayas. Geographical distance was not found to be related to genetic divergence. The study suggests that O. sativa contains innumerable but divergent forms, and its classification into definite varietal groups on an arbitrary basis such as isolation barrier, sexual affinity or geographic distribution would be far from reality.