Ecology and diversity of freshwater shrimps in Banco National Park, Côte d’Ivoire (Banco River Basin)

Shrimps are an important component of river invertebrate assemblages in tropical freshwater where they are a controlling group in food webs. In order to determine shrimp diversity in the Banco Basin (Côte d’Ivoire, West Africa) and examine whether the patterns of species distribution were related to environmental conditions, six sites were monitored. Sampling was conducted in 2008 during February, May, September and November using a long-handled net (25-cm diameter, 2-mm mesh). For each site, we measured environmental variables (conductivity, pH, water temperature, dissolved oxygen, turbidity, current speed, and water depth and width). Three shrimp species, Macrobrachium thysi (Powell 1980), Macrobrachium dux (Lenz 1910) and Desmocaris trispinosa (Aurivillius 1898) were identified. D. trispinosa was the largest distributed (more than 50% of occurrence) and the most abundant (67% of total number of specimens caught). It was followed by M. thysi with 47% and 32% of occurrence and abundance, respectively. Canonical correspondence analysis (CCA) showed a spatial distribution of the shrimp community, significantly influenced by width, depth, conductivity, type of substrate, turbidity and dissolved oxygen. Due to the fact that the Banco River hosts an endemic species in Côte d’Ivoire (Macrobrachium thysi), the conservation of integrity of this basin was recommended

Insights into the high-energy γ-ray emission of Markarian 501 from extensive multifrequency observations in the Fermi era

We report on the γ-ray activity of the blazar Mrk 501 during the first 480 days of Fermi operation. We find that the average Large Area Telescope (LAT) γ-ray spectrum of Mrk 501 can be well described by a single power-law function with a photon index of 1.78 ± 0.03. While we observe relatively mild flux variations with the Fermi-LAT (within less than a factor of two), we detect remarkable spectral variability where the hardest observed spectral index within the LAT energy range is 1.52 ± 0.14, and the softest one is 2.51 ± 0.20. These unexpected spectral changes do not correlate with the measured flux variations above 0.3 GeV. In this paper, we also present the first results from the 4.5 month long multifrequency campaign (2009 March 15-August 1) on Mrk 501, which included the Very Long Baseline Array (VLBA), Swift, RXTE, MAGIC, and VERITAS, the F-GAMMA, GASP-WEBT, and other collaborations and instruments which provided excellent temporal and energy coverage of the source throughout the entire campaign. The extensive radio to TeV data set from this campaign provides us with the most detailed spectral energy distribution yet collected for this source during its relatively low activity. The average spectral energy distribution of Mrk 501 is well described by the standard one-zone synchrotron self-Compton (SSC) model. In the framework of this model, we find that the dominant emission region is characterized by a size ≲0.1 pc (comparable within a factor of few to the size of the partially resolved VLBA core at 15-43 GHz), and that the total jet power (≃1044 erg s-1) constitutes only a small fraction (∼10-3) of the Eddington luminosity. The energy distribution of the freshly accelerated radiating electrons required to fit the time-averaged data has a broken power-law form in the energy range 0.3 GeV-10 TeV, with spectral indices 2.2 and 2.7 below and above the break energy of 20 GeV. We argue that such a form is consistent with a scenario in which the bulk of the energy dissipation within the dominant emission zone of Mrk 501 is due to relativistic, proton-mediated shocks. We find that the ultrarelativistic electrons and mildly relativistic protons within the blazar zone, if comparable in number, are in approximate energy equipartition, with their energy dominating the jet magnetic field energy by about two orders of magnitude. © 2011. The American Astronomical Society

Freshwater snail distribution related to environmental factors in Banco National Park, an urban reserve in the Ivory Coast (West Africa)

Freshwater snails and environmental variables were studied at seven stations along the Banco River (Ivory Coast;West Africa) from March to October 2008. Two species (Physa marmorata (Physidae) and Bulinus forskalii (Planorbidae) were recorded only at one sampling site. This station which received domestic sewage from the neighbouring cities was characterized by the highest conductivity and pH and the lowest values of dissolved oxygen. Multiple stepwise regression analysis showed that snail densities were probably influenced by conductivity, dissolved oxygen, pH, and canopy cover. Also, snail dynamics showed a seasonal pattern, with peak population densities and recruitment of young generations during rainy periods. This study highlighted the impacts of sewage on snail diversity and distribution in the Banco River. Overall, this paper strengthens the viewpoint that the Banco River management should be implemented to lessen the impact of anthropogenic activities on the ecology of the Banco National Park.Key words: freshwater snails, dynamic, Banco River, Ivory Coast

A snapshot of the emerging tomato genome sequence

The genome of tomato (Solanum lycopersicum L.) is being sequenced by an international consortium of 10 countries (Korea, China, the United Kingdom, India, the Netherlands, France, Japan, Spain, Italy, and the United States) as part of the larger \u201cInternational Solanaceae Genome Project (SOL): Systems Approach to Diversity and Adaptation\u201d initiative. The tomato genome sequencing project uses an ordered bacterial artificial chromosome (BAC) approach to generate a high-quality tomato euchromatic genome sequence for use as a reference genome for the Solanaceae and euasterids. Sequence is deposited at GenBank and at the SOL Genomics Network (SGN). Currently, there are around 1000 BACs finished or in progress, representing more than a third of the projected euchromatic portion of the genome. An annotation effort is also underway by the International Tomato Annotation Group. The expected number of genes in the euchromatin is 3c40,000, based on an estimate from a preliminary annotation of 11% of finished sequence. Here, we present this first snapshot of the emerging tomato genome and its annotation, a short comparison with potato (Solanum tuberosum L.) sequence data, and the tools available for the researchers to exploit this new resource are also presented. In the future, whole-genome shotgun techniques will be combined with the BAC-by-BAC approach to cover the entire tomato genome. The high-quality reference euchromatic tomato sequence is expected to be near completion by 2010