995 resultados para 209-1274


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There are a lot of evidence that show hvdrocarbones cause some defect in reproduction and growth of bivalves. Bivalves are filter-feeder, thus accumulate more hydrocarbones in their tissue. In this study adult pearl producing oysters (Pinctada fucata) are used for all experimens. Samples of oysters, water and sediment from four natural beds; Nakhiloo (clean), Hendurabi (semipolluted), Lavan 1 (semipolluted) and Lavan 2 (polluted) were gatherd for 13 succesive months. Temperature, salinity, pH, oxygen and turbidity were recorded in each sampling. Oysters were kept in laboratory for adapation and then their length (DVM) were measured. Hemolymph samples were collected by insuline syring. Sediments and soft tissues of oysters were dissolved in carbon tetrachloride and when heated to extract oil hydrocarbones. UV, GC and IR were used to assay oil hydrocarbones. Accumulation of hydrocabones in soft tissue were as follows : Kakhiloo

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依据历年馆藏的鱼类标本和资料,采用多元逐步回归与多项式逐步回归的分析方法,系统分析了滇中6个高原湖泊鱼类的物种丰度、特有种以及属的数目与7个主要湖泊环境因子之间的关系。分析结果显示,控制湖泊鱼类物种丰度、特有种数和属数的关键湖泊环境因子是湖泊面积和湖岸线长度;其中与湖泊面积呈显著正相关,而与湖岸线长度呈负相关。分析不停留于这一常规的横向比较,而是从历史生物地理学的角度,更深入一步揭示了滇中6个湖泊鱼类多样性的演化实质上是受湖泊的发育阶段所控制的。

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2003 年1 月, 在广西壮族自治区天峨县红水河水系地下河采集到一批盲鱼标本。经鉴定, 为高原鳅 属Triplophysa 一未经发表的新种。新种天峨高原鳅Triplophysa tianeensis sp1nov1 与个旧盲高原鳅T. gejiuensis 、 石林盲高原鳅T. shilinensis 、阿庐高原鳅T. aluensis 和南丹高原鳅T. nandanensis 相似; 本新种腹鳍末端不达 肛门, 尾鳍分枝鳍条16 , 可进一步与个旧盲高原鳅和石林盲高原鳅(腹鳍末端达到肛门, 尾鳍分枝鳍条14~ 15) 相区别; 本新种背鳍起点位于体之中点、腹鳍起点之后, 肛门紧靠臀鳍起点, 可进一步与阿庐高原鳅(背 鳍起点靠近吻端、位于腹鳍起点之前, 肛门距臀鳍起点仍有一段距离) 相区别。本新种与同分布于红水河水系 的南丹高原鳅Triplophysa nandanensis Lan et al1 较为相似; 但二者区别明显: 新种背鳍分枝鳍条7 、胸鳍分枝鳍 条9 、腹鳍分枝鳍条6 、背鳍外缘平截、背鳍起点位于腹鳍起点之后, 后者背鳍分枝鳍条8 、胸鳍分枝鳍条10~ 11 、腹鳍分枝鳍条7 、背鳍外缘凹入、背鳍起点位于腹鳍起点之前; 此外, 新种的穴居特征更为显著: 眼极度 退化、头长为眼径1618~3218 (2510) 倍、部分个体无色素斑且各鳍无斑点, 而南丹高原鳅眼小、头长为眼径 417~910 (715) 倍、体和头背侧密布云状斑且各鳍均具点状斑。

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《胞内共生与细胞研究》( 《Endocytobiosis and Cell Research》)是由国际胞内共生学会(International Society of Endocytobiology, ISE)主办的期刊, 它主要发表有关内共生物(endosy mbioses)和真核细胞的起源、发展、分化、进化和系统发育的研究论文. 在胞内共生和真核细胞的起源进化研究领域享有声誉. 去年该杂志发表了我国学者李靖炎先生的长篇论著“The primitive nucleus model and the origin of the cell nucleus(原始细胞核的模型与细胞核的起源)”(见1999, 13(1-3):1-86). 国外一家 SCI 收录的专业性刊物为中国学者发表一篇长达86页的 Review, 实不多见, 是我国学者在此领域的殊荣。

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Fishing communities that have exploited the resource for generations constitute the main stakeholder groups in the fisheries of Lake Victoria. Several studies have examined Uganda's Lake Victoria fishing communities and characterised key stakeholders at community level over the last decade (SEDAWOG 1999a and b; Geheb 1997; FeSEP 1997; Kitakule 1991). The communities are made up of scattered settlements at the shores and on islands. The categories of people living in these communities include fishers who consist primarily of large numbers of male youths who provide labour to boat and gear owners. There are resident and non-resident fish traders who after securing their supplies at the beaches, depart for their market destinations. In addition, there are fish processors, mostly operating traditional and improved smoking kilns. Many other people, dealing in provisions and supplies also stay at the beaches, their activities depending on the level of fish catch. The fishing communities of Lake Victoria, Uganda, include auxiliary livelihood activities such as boat building, net repairing and transportation; bait supply and beachside kiosks, video halls and retail shop business. Other economic activities are brick making, charcoal burning/wood trade, farming and livestock keeping.

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The artisanal fish preservation methods in Uganda are characterized by extreme operating conditions. Consequently, vital nutritional components diminish in value and quantity which renders fish consumer nutritionally insecure. To establish the magnitude of nutritional loss, duplicate samples of Mukene Rastrineobola argentea were collected from Kiyindi landing site on L. Victoria and Moone landing site on L. Kyoga. Each set of duplicate samples was divided into five portions and kept on ice. For each preservation method a portion was processed into respective products at Food Bioscience and Agri-Business Laboratories aside from the control (fresh) sample. Both preserved and control samples were analysed for nutrient loss at Department of Chemistry, Makerere University using AOAC methods. The composition of fatty acids was determined by methanolysis gas chromatography and Mass spectrophotometry of the resultant methyl esters. The results indicate that nutrients of all preserved samples did not vary significantly from the control except for some fatty acids. The Eicosapentaenoic acid (EPA) in fresh samples declined from 6.72% to 1.08% in deep-fried samples constituting 83.93% nutrient loss. The sum ratio w3:w6 as well as EPA: DHA (Docosahexaenoic) ratio in fried samples also varied significantly (p<0.5) lower than 0.668 and 0.20 for the average of either preservation methods and experts recommended ratio respectively. Further research has been recommended to ascertain the causative factor, since Mukene frying is being promoted in the Great lakes region as alternative method to sun-drying. In conclusion, regular consumers of fried Mukene do not benefit much from the nutritional and health attributes of Omega 3 and 6.

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Aquatic macro-invertebrates encompass all those organisms that be seen with unaided eyes. Most macro-invertebrates are categorised as semi-aquatic in that they are aquatic in early stages, but live as terrestrial organisms as adults, while others like gastropods, bivalves, Oligochaetae, Hirudinae and ostracods are exclusively aquatic. Some of them such as mayflies lay eggs in water and subsequent stages also live in water until adulthood when they emerge to live a terrestrial life. In others, eggs are laid near the water, while some like members of Tendipedidae (midges) lay their eggs on the leaves of aquatic macrophytes and after hatching their larvae creep into water