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Shang Wang Raymond M. Dong Christina Z. Dong Liuqin Huang Hongchen Jiang Yuli Wei Liang Feng Deng Liu Guifang Yang Chuanlun Zhang Hailiang Dong 《地学前缘(英文版)》2012,3(3):335-349
The Three Gorges Dam(TGD) of the Yangtze River.China,is one of the largest irrigation and hydroelectric engineering projects in the world.The effects of huge man-made projects like TGD on fauna and macrophyte are obvious,mainly through changes of water dynamics and flow pattern;however, it is less clear how microorganisms respond to such changes.This research was aimed to examine differences in microbial diversity at different seasons and locations(in front of and behind the TGD).In addition, differences between particle-attached and free-living communities were also examined.The community structures of total and potentially active microorganisms in the water columns behind and in front of the TGD were analyzed with the DNA- and RNA-based 16S rRNA gene phylogenetic approaches over three different seasons.Clone libraries of 16S rRNA genes were prepared after amplification from extracted DNA and.for some samples,after preparing cDNA from extracted rRNA.Differences were observed between sites at different seasons and between free-living and particle-attached communities.Both bacterial and archaeal communities were more diverse in summer than in winter, due to higher nutrient levels and warmer temperature in summer than in winter.Particle-attached microorganisms were more diverse than free-living communities,possibly because of higher nutrient levels and heterogeneous geochemical micro-environments in particles.Spatial variations in bacterial community structure were observed,i.e..the water reservoir behind the TGD(upstream) hosted more diverse bacterial populations than in front of the dam(downstream),because of diverse sources of sediments and waters from upstream to the reservoir.These results have important implications for our understanding of responses of microbial communities to environmental changes in river ecosystems affected by dam construction. 相似文献
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张志南 《中国海洋大学学报(自然科学版)》1990,(3)
记述了渤海中部在站位DA18、水深27m采到的海洋线虫一新种,渤海海线虫Thalassironus bohaiensis sp nov该新种的个体大小和De Man比值(a.b.c)与Thalassiro-nus bipartitus(Wieser,1953)十分相似,但雄性副交接刺的结构,两种有显著的差异。新种的副交接刺末端钝且内凹,在腹侧近末端有一明显的小突起,而相近种的副交接刺末端尖锐,没有任何突起。此外,新种雄性交接刺长度也与相近种有明显的差别(62—67μmvs 52μm)列表比较了新种与相近种以及该属目前已报导的其他三个种的详细形态学特征。模式标本保存在青岛海洋大学海洋生物系。 相似文献
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Prevalence of Acanthamoebae, Naegleriae and Other Free-living Amoebae in the Course of Water Treatment in Three Well Waterworks Numerous species of free-living amoebae and other protozoa had been observed in the raw water of three representative waterworks with enriched well water. They were eliminated most effectively during the water treatment procedure. Acanthamoebae and Naegleriae including thermophilic strains of these genera could not be identified in any of the clear water samples. Acanthamoebae and Vannellae isolated from different samples exhibited repeatedly intracellular infections with bacteria of the genus Cytophaga. Their role as possible hosts of different pathogenic and non pathogenic bacteria like Legionella sp., Listeria sp., and Pseudomonas sp. is confirmed by this observation. As known from earlier findings in connection with the Acanthamoeba-Legionella model, it can be assumed, that bacteria multiplying in trophozoites or being enclosed in cysts are protected against high concentrations of chlorine and other biocides. 相似文献
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