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瘤背石磺线粒体基因组全序列分析   总被引:1,自引:0,他引:1  
采用LA-PCR技术对瘤背石磺线粒体基因组全序列进行了测定和分析。结果表明,瘤背石磺线粒体基因组序列全长13 957 bp,由22个tRNA、2个rRNA、13个蛋白编码基因和19个长度为2~138 bp的非编码区组成。4个蛋白质编码基因和8个tRNA基因从L链编码,其余基因均从H链编码。蛋白质基因的起始密码子,除ND2为TTG以外,均为典型的起始密码子ATN。COⅢCytb基因使用了不完全终止密码子T,其余基因均使用典型的TAA或TAG。预测了22个tRNA基因的二级结构,发现tRNASer缺少DHU臂,tRNASer和tRNAThr的反密码子环上有9个碱基,而不是通常的7个碱基。最长的非编码区含有类似于tRNA的二级结构。基于线粒体基因组编码的13个蛋白质的氨基酸序列,用NJ、MP、ME和UPGMA法构建系统进化树。分析6种软体动物之间的亲缘关系,结果与传统的系统分类基本一致。研究初步确定瘤背石磺与平疣桑椹石磺的亲缘关系比与凯尔特石磺的亲缘关系近。  相似文献   

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The freshwater characiform fish Prochilodus lineatus is a detritivorous species that has its native distribution area in South America but has been imported to China for aquaculture purposes. This is the first time that it is being reported in Vietnam, both from aquaculture and captured from a river channel. According to local authorities, the species is becoming increasingly important in local aquaculture and its spread can be expected. Keeping in mind the high biomass production in the rivers of its native distribution area, a successful establishment of P. lineatus into Vietnamese fresh waters may exert serious impacts on the local ecosystems.  相似文献   

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Four levels of fish oil and macroporous cation strong acid-resin volume ratios, 1:1, 2:1, 3:1, and 4:1, were used to determine the optimum ratio in terms of the quality of refined oil or fraction-1. Fraction-1 (freely flown oil or refined oil) and fraction-2 (oil retained in the column) were analyzed regarding their quality based on free fatty acid, refractive index, colour, fatty acid profile and sensory evaluation. The results showed that resin refining process significantly improved the fish oilÆs chemical, physical and sensory quality characteristics. The omega-3 fatty acid content in the refined oil fraction was maintained and the level in fraction-2 was significantly higher than the level in fraction-1. Sensory evaluation indicated that the fraction-1 was significantly better than fraction-2. The fish oil and resin volume ratio of 1:1 was found to be the best due to improvement in sensory and chemical characteristics.  相似文献   

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No abstract available for this article.  相似文献   

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  1. About 5–10% of the world's land surface is currently wetland but possibly >70% is already destroyed or impaired. Conservation of these unique ecosystems lags progress in other realms, reflected in high rates of biodiversity loss. Wetlands provide a range of critically important ecosystem services including fresh water, nutrient cycling, food and fibre production, carbon fixation and storage, flood mitigation and water storage; water treatment and purification and habitats for biodiversity. There is increasing recognition that these services provide real economic values.
  2. Wetlands are affected by numerous threats including habitat loss and degradation, climate change, pollution, invasive species, overharvesting and disease. The most serious impact is from habitat loss and degradation caused by upstream water resource developments and conversion to agriculture, industry and transport, and urban development.
  3. The status of the distribution and extent of the world's wetlands remains poorly known, varying among countries. Wetland loss has varied internationally, with generally higher impacts in the Northern Hemisphere, with its long history of conversion to urban centres, ports and agriculture and yet there are increasing losses occurring in developing continents in the south.
  4. Wetland conservation needs to focus primarily on identification of priority areas for biodiversity conservation and legal protection, including Ramsar‐listing. Identification of wetland biodiversity hotspots for conservation should be an imperative, with associated Ramsar‐listing. There also needs to be effective protection of flow regimes. Mitigation of other deleterious processes, pollution, overharvesting, invasive species and disease, also remains particularly important.
  5. Conservation of wetlands remains especially challenging, given the importance of fresh water for human communities, industry and agriculture. Without effective conservation actions, mitigation of threats, rigorous risk assessment and acknowledgement of the value of wetland ecosystem services, wetland conservation will continue to lag behind conservation in other realms in protecting the Earth's biodiversity.
Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

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Abstract– The eight papers resulting from the Ecological Genetics session of the symposium Ecology of Stream Fish: State of the Art and Future Prospects (Luarca, Spain, April 1998) describe the use of molecular genetic markers to investigate questions of population distinctness, interbreeding, and adaptation in five salmonid species. Widely contrasting ecological distinctions described in four species indigenous to western North America [steelhead (rainbow) trout, sockeye salmon, pink salmon and bull trout] reflect past natural and human-induced activities, serving to guide future management and conservation actions through optimizing adaptive opportunities, and preventing genetic losses through localized extinctions. Studies of brown trout contrast widespread introgressions from exogenous hatchery introductions that threaten the integrity of native Spanish populations with a reduced threat based on use of indigenous fish in Portuguese hatcheries. A 9-year study of natural progeny of two genetically distinct Swedish brown trout populations introduced to a previously trout-free area identifies apparent local adaptations as a model to guide other translocations.  相似文献   

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Abstract. Extracellular hacmolytic activities of Aeromonas salmonicida ssp. salmonicida to salmon red blood cells were shown to be due to different forms of the membrane-active enzyme glyccrophospholipidrcholcstcrol acyltransferase (GCAT). About 10% of the total haemolytic activity was due to a high molecular mass complex of LPS and GCAT (mol. mass >1000kDa), containing 35–50% neutral sugars and 1.5–2.0% protein. Some haemolytic activity (30–40% of total), corresponding to 50–70kDa by gel filtration, also contained GCAT-activity and may represent aggregated forms of GCAT. However, about 50% or more of the haemolytie activity was due to a protein of 26kDa free GCAT. Rabbit antibodies to GCAT neutralized the hacmolytic activity of both GCAT and GCAT-LPS. A transposon-produccd serinc protease negative mutant of the same A. salmonicida strain showed reduced haemolytic activity. The mutant produced a 38-kDa GCAT proform of low hacmolytic activity. The proform was processed by autogenous scrinc protease to a highly hacmolytic 26-kDa molecule with pl 6.3, similar to GCAT of the parent strain. The weakly haemolytic GCAT-LPS analogue of the mutant strain did not contain detectable amounts of the 26-kDa molecule and was not activated by proteases.  相似文献   

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