342 research outputs found

    Trophic ecology of three sympatric batoid species (Dasyatis pastinaca, Raja clavata, and Raja maderensis) from the Azores, NE Atlantic

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    ABSTRACT: Describing the trophic structure and interactions of demersal elasmobranch assemblages is fundamental to understanding food web dynamics and developing ecosystem-based management approaches. Stomach content analysis (SCA) and stable isotope ratios (SIA) of carbon (δ13C) and nitrogen (δ15N) from muscle were used to examine the dietary habits and intra- and interspecific trophic ecology of three sympatric batoid species (Dasyatis pastinaca, Raja clavata, and Raja maderensis) from the Azores, Northeast Atlantic. Data were nalyzed with respect to sex and maturity stages. SCA showed that D.pastinaca feeds mostly on crustaceans, whereas R. clavata and R. maderensis prey almost exclusively on teleosts, but not on the same species. Dasyatis pastinaca displayed higher δ13C and lower δ15N values compared to R. clavata and R. maderensis. Trophic niche breadth was variable, D. pastinaca and R. clavata had the broadest and the narrowest trophic breadth, respectively. Relative trophic position categorized D. pastinaca as a mesopredator, while R. clavata and R. maderensis occupied higher trophic positions. With size, R. clavata and R. maderensis shifted from small prey such as crustaceans to larger prey such as teleosts, and they also exhibited significant increases in δ15N with size. Dietary and isotopic overlap was overall low among species, but it was higher between R. clavata and R. maderensis, suggesting more similarity in diet and habitat use between them than with D. pastinaca. This study depicts trophic interactions and functional roles of three co-existing batoid species in the Azorean food webs. In addition to presenting new information on the trophic ecology of D. pastinaca and R. clavata, the present study provides, to our knowledge, the first description of the diet composition and trophic level of the Macaronesian endemic batoid R. maderensis.info:eu-repo/semantics/publishedVersio

    BCKDH: the missing link in apicomplexan mitochondrial metabolism is required for full virulence of Toxoplasma gondii and Plasmodium berghei

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    While the apicomplexan parasites Plasmodium falciparum and Toxoplasma gondii are thought to primarily depend on glycolysis for ATP synthesis, recent studies have shown that they can fully catabolize glucose in a canonical TCA cycle. However, these parasites lack a mitochondrial isoform of pyruvate dehydrogenase and the identity of the enzyme that catalyses the conversion of pyruvate to acetyl-CoA remains enigmatic. Here we demonstrate that the mitochondrial branched chain ketoacid dehydrogenase (BCKDH) complex is the missing link, functionally replacing mitochondrial PDH in both T. gondii and P. berghei. Deletion of the E1a subunit of T. gondii and P. berghei BCKDH significantly impacted on intracellular growth and virulence of both parasites. Interestingly, disruption of the P. berghei E1a restricted parasite development to reticulocytes only and completely prevented maturation of oocysts during mosquito transmission. Overall this study highlights the importance of the molecular adaptation of BCKDH in this important class of pathogens

    Mercury exposure and short-term consequences on physiology and reproduction in Antarctic petrels

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    Mercury (Hg) is a pervasive contaminant reaching Antarctic environments through atmospheric transport and deposition. Seabirds as meso to top predators can accumulate high quantities of Hg through diet. Reproduction is one of the most sensitive endpoints of Hg toxicity in marine birds. Yet, few studies have explored Hg exposure and effects in Antarctic seabirds, where increasing environmental perturbations challenge animal populations. This study focuses on the Antarctic petrel Thalassoica antarctica from Svarthamaren, Antarctica, where the world\u27s largest breeding population is thought to be in decline. Hg and the stable isotopes of carbon (δ13C, proxy of feeding habitat) and nitrogen (δ15N, trophic position/diet) were measured in red blood cells from 266 individuals over two breeding years (2012–13, 2013–14). Our aims were to 1) quantify the influence of individual traits (size and sex) and feeding ecology (foraging location, δ13C and δ15N values) on Hg exposure, and 2) test the relationship between Hg concentrations with body condition and breeding output (hatching success and chick survival). Hg concentrations in Antarctic petrels (mean ± SD, 0.84 ± 0.25, min-max, 0.42–2.71 μg g−1 dw) were relatively low when compared to other Antarctic seabirds. Hg concentrations increased significantly with δ15N values, indicating that individuals with a higher trophic level (i.e. feeding more on fish) had higher Hg exposure. By contrast, Hg exposure was not driven by feeding habitat (inferred from both foraging location and δ13C values), suggesting that Hg transfer to predators in Antarctic waters is relatively homogeneous over a large geographical scale. Hg concentrations were not related to body condition, hatching date and short-term breeding output. At present, Hg exposure is likely not of concern for this population. Nevertheless, further studies on other fitness parameters and long-term breeding output are warranted because Hg can have long-term population-level effects without consequences on current breeding success

    Mercury exposure and short-term consequences on physiology and reproduction in Antarctic petrels

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    Mercury (Hg) is a pervasive contaminant reaching Antarctic environments through atmospheric transport and deposition. Seabirds as meso to top predators can accumulate high quantities of Hg through diet. Reproduction is one of the most sensitive endpoints of Hg toxicity in marine birds. Yet, few studies have explored Hg exposure and effects in Antarctic seabirds, where increasing environmental perturbations challenge animal populations. This study focuses on the Antarctic petrel Thalassoica antarctica from Svarthamaren, Antarctica, where the world\u27s largest breeding population is thought to be in decline. Hg and the stable isotopes of carbon (δ13C, proxy of feeding habitat) and nitrogen (δ15N, trophic position/diet) were measured in red blood cells from 266 individuals over two breeding years (2012–13, 2013–14). Our aims were to 1) quantify the influence of individual traits (size and sex) and feeding ecology (foraging location, δ13C and δ15N values) on Hg exposure, and 2) test the relationship between Hg concentrations with body condition and breeding output (hatching success and chick survival). Hg concentrations in Antarctic petrels (mean ± SD, 0.84 ± 0.25, min-max, 0.42–2.71 μg g−1 dw) were relatively low when compared to other Antarctic seabirds. Hg concentrations increased significantly with δ15N values, indicating that individuals with a higher trophic level (i.e. feeding more on fish) had higher Hg exposure. By contrast, Hg exposure was not driven by feeding habitat (inferred from both foraging location and δ13C values), suggesting that Hg transfer to predators in Antarctic waters is relatively homogeneous over a large geographical scale. Hg concentrations were not related to body condition, hatching date and short-term breeding output. At present, Hg exposure is likely not of concern for this population. Nevertheless, further studies on other fitness parameters and long-term breeding output are warranted because Hg can have long-term population-level effects without consequences on current breeding success. Blood Hg concentrations in Antarctic petrels were driven by trophic position and were not related to short-term breeding output

    Clinical outcomes of biliary drainage of malignant biliary obstruction due to colorectal cancer metastases : a systematic review

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    Background and aims: Malignant biliary obstruction is an ominous complication of metastatic colorectal cancer (mCRC). Biliary drainage is frequently performed to relieve symptoms of jaundice or enable palliative systemic therapy, but effective drainage can be difficult to accomplish. The aim of this study is to summarize literature on clinical outcomes of biliary drainage in mCRC patients with malignant biliary obstruction.& nbsp; Methods: We searched Medline and EMBASE for studies that included patients with malignant biliary obstruction secondary to mCRC, treated with endoscopic and/or percutaneous biliary drainage. We summarized available data on technical success, clinical success, adverse events, systemic therapy administration and survival after biliary drainage.& nbsp; Results: After screening 3584 references and assessing 509 full-text articles, seven cohort studies were included. In these studies, rates of technical success, clinical success and adverse events varied between 63%-94%, 42%81%, and 19%-39%, respectively. Subsequent chemotherapy was administered in 17%-56% of patients. Overall survival varied between 40 and 122 days across studies (278-365 days in patients who received subsequent chemotherapy, 42-61 days in patients who did not).& nbsp; Conclusions: Successful biliary drainage in mCRC patients can be challenging to achieve and is frequently associated with adverse events. Overall survival after biliary drainage is limited, but is significantly longer in patients treated with subsequent systemic therapy. Expected benefits of biliary drainage should be carefully weighed against its risks

    LFI 30 and 44 GHz receivers Back-End Modules

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    The 30 and 44 GHz Back End Modules (BEM) for the Planck Low Frequency Instrument are broadband receivers (20% relative bandwidth) working at room temperature. The signals coming from the Front End Module are amplified, band pass filtered and finally converted to DC by a detector diode. Each receiver has two identical branches following the differential scheme of the Planck radiometers. The BEM design is based on MMIC Low Noise Amplifiers using GaAs P-HEMT devices, microstrip filters and Schottky diode detectors. Their manufacturing development has included elegant breadboard prototypes and finally qualification and flight model units. Electrical, mechanical and environmental tests were carried out for the characterization and verification of the manufactured BEMs. A description of the 30 and 44 GHz Back End Modules of Planck-LFI radiometers is given, with details of the tests done to determine their electrical and environmental performances. The electrical performances of the 30 and 44 GHz Back End Modules: frequency response, effective bandwidth, equivalent noise temperature, 1/f noise and linearity are presented

    Confirmation de QTL et validation de marqueurs SNPs associés à la résistance du niébé à Colletotrichum capsici, agent responsable de la maladie des taches brunes

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    Le niébé (Vigna unguiculata (L.) Walp.) est une légumineuse à graine très importante et constitue la principale source de protéines végétales pour l’alimentation des populations d’Afrique Subsaharienne. Sa production au Burkina Faso est entravée par la maladie des taches brunes provoquée par un champignon, Colletotrichum capsici (Syd.) Butler et Bisby. C’est dans la perspective d’accroître la productivité du niébé que nous avons entrepris de renforcer la lutte variétale contre cet agent pathogène. L’identification de marqueurs SNPs (Single Nucleotide Polymorphism) et QTL liés à la résistance à la maladie des taches brunes a été entrepris à partir d’une population biparentale F2 issus du croisement entre la variété sensible Tiligré et celle résistante KN-1. L’analyse QTL de la résistance du niébé à C. capsici à partir de la méthode ICIM add. a permis de confirmer et de valider respectivement un QTL majeur dénommé qBBDR2.1 et 9 marqueurs SNPs convertis, lesquels ont été cartographiés sur le chromosome Vu02 du niébé. Ce QTL dominant a présenté des effets additifs élevés liés aux allèles favorables de KN-1 et des valeurs de PVE de l’ordre de 51,50% et 55,33%, respectivement aux 21ème et 28ème JAI. English title: Confirmation of QTL mapping and validation of SNPs markers associated to cowpea resistance to Colletotrichum capsici, causal agent of brown blotch disease Cowpea (Vigna unguiculata (L.)Walp.) is one of the most important grain legume crops and constitutes the main source of plant protein for people food in sub-Saharan Africa. Cowpea production in Burkina Faso is constrained by brown blotch disease caused by a fungal,  Colletotrichum capsici (Syd.) Butler and Bisby. In order to increase cowpea productivity we initiated a project to enhance host plant resistance to control the pathogen. The identification of SNP (Single Nucleotide Polymorphism) markers and QTL associated with brown blotch disease resistance was undertaken from a bi-parental F2 population resulting from a cross between the sensitive variety Tiligre and the resistant KN-1 to the disease. QTL analysis of cowpea resistance to C. capsici using the ICIM add method. Allowed to confirm and validate respectively a major QTL named qBBDR2.1 and 9 converted SNP markers, which were mapped on cowpea chromosome Vu02. This dominant QTL showed higher additive effects associated to alleles from KN-1 and PVE values of 51.50% and 55.33% respectively at 21 and 28 days after inoculatio

    Mercury content in commercial pelagic fish and its risk assessment in the Western Indian Ocean,” Sci.

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    Abstract As top predators of pelagic food webs, large fish naturally bioaccumulate mercury (Hg). Determining Hg burdens in commercialized fish is essential considering the concern about effects of contaminants on human health and the legal thresholds that are therefore set for local consumption and/or exportation. Total Hg levels were measured in the muscular tissue of 183 fish of five commercially important species from the tropical zone of the Western Indian Ocean. All individuals were measured and sexed in order to study the impregnation of Hg with size and sex within each species. Values of Hg found in this part of the Indian Ocean were comparable to Hg in muscular tissue of the same species studied in other areas. The highest Hg levels were noted in Swordfish (Xiphias gladius) caught in waters surrounding Reunion Island (3.97 ± 2.67 μg g − 1 dry weight). Following the Swordfish, in decreasing order of Hg content, were the Yellowfin Tuna (Thunnus albacares) and the Skipjack (Katsuwonus pelamis), then the Common Dolphinfish (Coryphaena hippurus) and the Wahoo (Acanthocybium solandri). In the North of the Mozambique Channel, Swordfish had higher Hg levels than Yellowfin Tunas, and Dolphinfish exhibited intermediate Hg levels. The size of a fish was a determining factor of its Hg burden, as was the species. Differences in size-normalized Hg levels were observed between the two study zones for Swordfish and Common Dolphinfish. Sex, in contrast, did not influence Hg levels suggesting that females and males have similar feeding habits. The muscular Hg levels presented here suggest that consumers of fish originating from theWestern Indian Ocean should limit themselves to one Swordfish based meal per week, or one fish meal a day if they choose to eat tuna or Common Dolphinfish
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