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41.
N Lübcker J Dabrowski TA Zengeya PJ Oberholster G Hall S Woodborne 《African Journal of Aquatic Science》2016,41(4):399-411
The alien invasive silver carp Hypophthalmichthys molitrix established a self-sustaining feral population in an oligotrophic impoundment, Flag Boshielo Dam, in South Africa. The ability of this population to persist in a dam with low algal biomass (median annual suspended chlorophyll a = 0.08 µg l?1), and limited access to rivers considered large enough for successful spawning, has implications for their invasive potential in other systems. Stomach content and stable isotope analysis were used to assess the trophic ecology of H. molitrix, which was then compared with indigenous Mozambique tilapia Oreochromis mossambicus, on a seasonal basis during 2011. Hypophthalmichthys molitrix are generalist filter feeders, with a diet consisting primarily of sediment, vegetative detritus, dinoflagellates and diatoms. The dominance of sediments in their stomachs suggests occasional benthic scavenging. However, H. molitrix occupied a higher trophic level (TL = 2.8) than expected, suggesting that this population subsidised their diet with an unidentified dietary constituent, characterised by enriched nitrogen values. Although the stomach contents indicated dietary overlap between H. molitrix and O. mossambicus, stable isotopes revealed fine-scale resource partitioning, despite both species occupying the same trophic level. Nonetheless, the persistence of this feral H. molitrix population in an oligotrophic impoundment highlights their phenotypic plasticity. 相似文献
42.
Carolyn TA Herzig Ray W Waters Cynthia L Baldwin Janice C Telfer 《BMC evolutionary biology》2010,10(1):181
Background
The scavenger receptor cysteine rich (SRCR) domain is an ancient and conserved protein domain. CD163 and WC1 molecules are classed together as group B SRCR superfamily members, along with Spα, CD5 and CD6, all of which are expressed by immune system cells. There are three known types of CD163 molecules in mammals, CD163A (M130, coded for by CD163), CD163b (M160, coded for by CD163L1) and CD163c-α (CD163L1 or SCART), while their nearest relative, WC1, is encoded by a multigene family so far identified in the artiodactyl species of cattle, sheep, and pigs. 相似文献43.
TA Nichols Bruce Pulford A Christy Wyckoff Crystal Meyerett Brady Michel Kevin Gertig Edward A Hoover Jean E Jewell Glenn C Telling Mark D Zabel 《朊病毒》2009,3(3):171-183
Chronic wasting disease (CWD) is the only known transmissible spongiform encephalopathy affecting free-ranging wildlife. Although the exact mode of natural transmission remains unknown, substantial evidence suggests that prions can persist in the environment, implicating components thereof as potential prion reservoirs and transmission vehicles.1–4 CWD-positive animals may contribute to environmental prion load via decomposing carcasses and biological materials including saliva, blood, urine and feces.5–7 Sensitivity limitations of conventional assays hamper evaluation of environmental prion loads in soil and water. Here we show the ability of serial protein misfolding cyclic amplification (sPMCA) to amplify a 1.3 × 10−7 dilution of CWD-infected brain homogenate spiked into water samples, equivalent to approximately 5 × 107 protease resistant cervid prion protein (PrPCWD) monomers. We also detected PrPCWD in one of two environmental water samples from a CWD endemic area collected at a time of increased water runoff from melting winter snow pack, as well as in water samples obtained concurrently from the flocculation stage of water processing by the municipal water treatment facility. Bioassays indicated that the PrPCWD detected was below infectious levels. These data demonstrate detection of very low levels of PrPCWD in the environment by sPMCA and suggest persistence and accumulation of prions in the environment that may promote CWD transmission.Key words: prions, chronic wasting disease, water, environment, serial protein misfolding cyclic amplification 相似文献
44.
Freshwater crayfish invasions have been studied around the world, but less so in Africa, a continent devoid of native freshwater crayfish. The present study reviews historical and current information on alien freshwater crayfish species introduced into South Africa and aims to indicate which areas are at risk from invasion. As is the case elsewhere, South Africans have shown a keen interest in both farming and keeping freshwater crayfish as pets, which has resulted in Cherax cainii, Cherax destructor, Cherax quadricarinatus and Procambarus clarkii being introduced to the country. There is evidence of successful establishment in the wild for C. quadricarinatus and P. clarkii in different parts of the country. Species distribution models suggest that the eastern part of the country and parts of the Eastern and Western Cape are at higher risk of invasion. At present, illegal translocations represent the most likely pathway of crayfish spread in South Africa. A continued risk of invasion by freshwater crayfish species in South Africa is highlighted, which reinforces the need for more research, as well as for strong mitigation measures, such as stronger policing of existing regulations, management or eradication where feasible and public education. 相似文献
45.
Bons N Lehmann S Nishida N Mestre-Frances N Dormont D Belli P Delacourte A Grassi J Brown P 《Comptes rendus biologies》2002,325(1):67-74
Eleven Microcebus murinus (lemur) primates were intracerebrally or orally infected by bovine spongiform encephalopathy (BSE) or macaque-adapted BSE (MBSE) brain homogenates. In many BSE and MBSE infected lemurs, but not in animals inoculated with normal bovine brain, persistent behavioral changes occurred as early as 3 months, and neurological signs as early as 13 months after infection. Immunohistochemical examination of animals sacrificed during the incubation period revealed an abnormal accumulation of 'prion' protein (PrP) in the intestinal wall, intestinal nervous plexus, mesenteric lymph nodes and spleen, and in the clinical stage, also in the brain. In MBSE-inoculated animals, proteinase K resistance of the PrP (PrPres) was confirmed by Western blot in the spleen and the brain. Obvious signs of neurodegeneration were observed in all infected animals characterized by hyperaggregated and paired-helical filaments-immunoreactive Tau proteins, beta 42-amyloid plaques and astrogliosis. Additionally, PrPres was present in the ganglion cells of the retina in diseased animals after either intracerebrally or oral infection by the BSE or MBSE agent. These results show that the microcebe is susceptible to the BSE infectious agent via intracerebral and oral routes with comparatively short incubation periods compared to simians, and could be a useful animal model to study the pathophysiology of disease transmission in primates. 相似文献
46.
MARTINA VYSKOILOV MARKTA ONDRAKOV ANDREA IMKOV JEAN‐FRANOIS MARTIN 《Molecular ecology resources》2007,7(4):701-704
Fourteen polymorphic microsatellites were isolated from Neogobius kessleri, a benthic fish of Ponto‐Caspian origin which has been recently introduced into the Middle and Upper Danube River. Number of alleles and heterozygosity per locus in a sample of 32 fish individuals ranged from two to four and from 0.13 to 0.75, respectively. These primers will be useful in determining the population structure of N. kessleri. In addition, successful cross‐amplification was obtained for four related species, N. melanostomus, N. fluviatilis, N. gymnotrachelus and Proterorhinus marmoratus. These microsatellite loci may be useful for the evaluation of the origin of non‐native goby populations. 相似文献
47.
Bas Brinkhof Helena TA van Tol Marian JA Groot Koerkamp Frank M Riemers Sascha G IJzer Kaveh Mashayekhi Henk P Haagsman Bernard AJ Roelen 《BMC genomics》2015,16(1)
Background
Genes and signalling pathways involved in pluripotency have been studied extensively in mouse and human pre-implantation embryos and embryonic stem (ES) cells. The unsuccessful attempts to generate ES cell lines from other species including cattle suggests that other genes and pathways are involved in maintaining pluripotency in these species. To investigate which genes are involved in bovine pluripotency, expression profiles were generated from morula, blastocyst, trophectoderm and inner cell mass (ICM) samples using microarray analysis. As MAPK inhibition can increase the NANOG/GATA6 ratio in the inner cell mass, additionally blastocysts were cultured in the presence of a MAPK inhibitor and changes in gene expression in the inner cell mass were analysed.Results
Between morula and blastocyst 3,774 genes were differentially expressed and the largest differences were found in blastocyst up-regulated genes. Gene ontology (GO) analysis shows lipid metabolic process as the term most enriched with genes expressed at higher levels in blastocysts. Genes with higher expression levels in morulae were enriched in the RNA processing GO term. Of the 497 differentially expressed genes comparing ICM and TE, the expression of NANOG, SOX2 and POU5F1 was increased in the ICM confirming their evolutionary preserved role in pluripotency. Several genes implicated to be involved in differentiation or fate determination were also expressed at higher levels in the ICM. Genes expressed at higher levels in the ICM were enriched in the RNA splicing and regulation of gene expression GO term. Although NANOG expression was elevated upon MAPK inhibition, SOX2 and POU5F1 expression showed little increase. Expression of other genes in the MAPK pathway including DUSP4 and SPRY4, or influenced by MAPK inhibition such as IFNT, was down-regulated.Conclusion
The data obtained from the microarray studies provide further insight in gene expression during bovine embryonic development. They show an expression profile in pluripotent cells that indicates a pluripotent, epiblast-like state. The inability to culture ICM cells as stem cells in the presence of an inhibitor of MAPK activity together with the reported data indicates that MAPK inhibition alone is not sufficient to maintain a pluripotent character in bovine cells.Electronic supplementary material
The online version of this article (doi:10.1186/s12864-015-1448-x) contains supplementary material, which is available to authorized users. 相似文献48.
Rushton JP Bons TA Vernon PA Cvorović J 《Proceedings. Biological sciences / The Royal Society》2007,274(1619):1773-1777
We carried out two studies to test the hypothesis that genetic and environmental influences explain population group differences in general mental ability just as they do individual differences within a group. We estimated the heritability and environmentality of scores on the diagrammatic puzzles of the Raven's Coloured and/or Standard Progressive Matrices (CPM/SPM) from two independent twin samples and correlated these estimates with group differences on the same items. In Study 1, 199 pairs of 5- to 7-year-old monozygotic (MZ) and dizygotic (DZ) twins reared together provided estimates of heritability and environmentality for 36 puzzles from the CPM. These estimates correlated with the differences between the twins and 94 Serbian Roma (both rs=0.32; Ns=36; ps<0.05). In Study 2, 152 pairs of adult MZ and DZ twins reared apart provided estimates of heritability and environmentality for 58 puzzles from the SPM. These estimates correlated with the differences among 11 diverse samples including (i) the reared-apart twins, (ii) another sample of Serbian Roma, and (iii) East Asian, White, South Asian, Coloured and Black high school and university students in South Africa. In 55 comparisons, group differences were more pronounced on the more heritable and on the more environmental items (mean rs=0.40 and 0.47, respectively; Ns=58; ps<0.05). After controlling for measurement reliability and variance in item pass rates, the heritabilities still correlated with the group differences, although the environmentalities did not. Puzzles found relatively difficult (or easy) by the twins were those found relatively difficult (or easy) by the others (mean r=0.87). These results suggest that population group differences are part of the normal variation expected within a universal human cognition. 相似文献
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