Fish community response to the longitudinal environmental gradient in Czech deep-valley reservoirs: Implications for ecological monitoring and management

Ecological quality assessment of non-natural water bodies is, in contrast to natural systems, less developed and requires determining biological indicators that reliably reflect environmental conditions and anthropogenic pressures. This study was motivated to propose fish indicators appropriate for assessment of reservoir ecosystems in central Europe. We analysed changes in water quality, total biomass and the taxonomic, trophic and size composition of fish communities along the longitudinal axes of four elongated, deep-valley reservoirs. Due to high nutrient inputs from their catchments, the reservoirs exhibited pronounced within-system gradients in primary productivity and water transparency. Although fish communities were similar among the reservoirs and dominated by few native species, the community structure and biomass systematically changed along the longitudinal axes of the reservoirs. The biomass and proportion of planktivores/benthivores in the fish community were highest at eutrophic sites near the river inflow and declined substantially towards deep, more oligotrophic sites close to the dam. The biomass and proportion of piscivores significantly increased downstream within the reservoirs alongside improving water quality. At species level, perch Perca fluviatilis and bream Abramis brama responded most sensitively, although in opposite directions, to the longitudinal environmental gradient. The major longitudinal changes in fish community characteristics were found to be consistent between pelagic and benthic habitats. The results of this study suggest that fish communities are appropriate indicators of eutrophication and can be used for ecological quality assessment of non-natural lentic water bodies, such as reservoirs. Moreover, our results underline the necessity to consider within-system gradients in water quality and the fish community when planning sampling programmes for deep-valley reservoirs.     

Calcium exchanges in Anodonta cygnea: barriers and driving gradients

Electrical potential differences between the haemolymph and the extrapallial fluid, and between the haemolymph and the mantle cavity fluid, and ionic concentrations of calcium in the haemolymph and in extrapallial fluid were measured in vivo in Anodonta cygnea. The electrochemical potential of ionic calcium in the haemolymph is clearly above the electrochemical potential of ionic calcium in the environment and is very nearly in equilibrium with that of the extrapallial fluid. Simultaneous measurements of carbon dioxide partial pressure and pH in the extrapallial fluid showed that in this compartment ionic calcium is clearly above saturation. It is proposed that calcium deposition is regulated through the secretion of the organic matrix and by controlling the pH and the carbon dioxide partial pressure of the extrapallial fluid. An estimation of the minimum positive balance of calcium required to sustain shell growth together with the electrophysiological characterization of the mantle cavity epithelium showed that this tissue is not the route of entry of calcium into the animal.Abbreviations BW body weight - DW dry weight - E_EPF-S chemical potential difference - EPF extrapallial fluid - G_tot total conductance - I_sc short-circuit current - K_sp solubility product - MCE mantle cavity epithelium - MCF mantle cavity fluid - OME outer mantle epithelium - PCO₂ partial pressure of carbon dioxide - PVC Poly(vinyl chloride) - S shell - SEM standard error of mean - V _ic intracellular electrical potential - V _oc open-circuit voltage     

Ordination of epiphytic bryophyte communities in a wet-temperate coniferous forest,South-Coastal British Columbia

Three coniferous tree species (Pseudotsuga menziesii, Tsuga heterophylla, and Thuja plicata) at Capilano Canyon, British Columbia, were studied for their epiphytic communities. Quantitative data were obtained for fourteen bryophyte species by sampling at heights of 0.5 m, 1 m and 2 m above ground level. Scapania bolanderi is an abundant and widely distributed species; Dicranum fuscescens, Bazzania denudata, Lepidozia reptans and Hypnum circinale are also common. An environmentally uniform study area was chosen to minimize the effects of factors other than bark and elevation on the distribution of epiphytes. In general, tree species are similar in terms of their epiphytic assemblages, but ordination methods using quantitative data exposed compositional variation that may be explained by differences in microclimate and bark-type. In this respect, the results point the way to further studies to examine epiphyte associations in closer detail, and to relate these associations to specific factors in the microenvironment.Nomenclature for vascular plants follows Hitchcock & Cronquist (1973); bryophyte nomenclature follows Schofield (1976) for mosses and Stotler & Crandall-Stotler (1977) for hepatics.We thank Dr. W. B. Schofield for aiding in bryophyte identification.     

Consensus Brain-derived Protein,Extraction Protocol for the Study of Human and Murine Brain Proteome Using Both 2D-DIGE and Mini 2DE Immunoblotting

Two-dimensional gel electrophoresis (2DE) is a powerful tool to uncover proteome modifications potentially related to different physiological or pathological conditions. Basically, this technique is based on the separation of proteins according to their isoelectric point in a first step, and secondly according to their molecular weights by SDS polyacrylamide gel electrophoresis (SDS-PAGE). In this report an optimized sample preparation protocol for little amount of human post-mortem and mouse brain tissue is described. This method enables to perform both two-dimensional fluorescence difference gel electrophoresis (2D-DIGE) and mini 2DE immunoblotting. The combination of these approaches allows one to not only find new proteins and/or protein modifications in their expression thanks to its compatibility with mass spectrometry detection, but also a new insight into markers validation. Thus, mini-2DE coupled to western blotting permits to identify and validate post-translational modifications, proteins catabolism and provides a qualitative comparison among different conditions and/or treatments. Herein, we provide a method to study components of protein aggregates found in AD and Lewy body dementia such as the amyloid-beta peptide and the alpha-synuclein. Our method can thus be adapted for the analysis of the proteome and insoluble proteins extract from human brain tissue and mice models too. In parallel, it may provide useful information for the study of molecular and cellular pathways involved in neurodegenerative diseases as well as potential novel biomarkers and therapeutic targets.     

A computationally efficient method for evaluating the gradient of 2D NOESY intensities

Summary A computationally efficient method for calculating the derivative of NOE intensities with respect to any parameter is presented. This method is based on an integral expression representing the gradient. We will derive this expression from first principles using standard perturbation expansion techniques, and show it to be equivalent to an analytical expression [Yip, P. and Case, D.A. (1989) J. Magn. Reson., 83, 643] Implementation of this method in a refinement scheme (NOE-MD) is also briefly mentioned.     

La flore probable : un mode d’expression des gradients écologiques en France

The application of the criterion of fidelity of plants to plants over four millions botanical observations in France is considered to characterize the ecology of 215,000 phytosociological surveys. Among those discriminant plants, some are missing of the surveys, but they can have a certain probability of occurrence: these plants are called “probable plants” and they represent the “probable flora” of a territory. The study of their geographical distribution shows ecological gradients of flora across France in a better way than only considering the botanical observations. In fact, this method mitigates the discontinuities of taxa observations whose absence may be due to historical and/or anthropogenic factors.