6 resultados para microbial source tracking, E. coli, SNP, CRISPR, faecal contamination, bacteriophage

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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由于含油污水灌溉、原油储存运输和石油冶炼过程中导致的泄漏事故等原因,石油类物质已经成为环境中的主要污染物之一。石油烃污染物对土壤微生物遗传多样性和群落结构的影响在国外已有一些报道,但有关于石油烃污染对稻田土壤微生物生态系统的影响一直以来一直没有一个全面和系统的认识。本论文首次采用传统微生物培养方法、常规生化分析方法与PC树DGGE现代分子生态学研究方法相结合的手段系统评价了长期石油污水灌溉对中国最大的石油类污水灌区-沈抚灌区的稻田土壤微生物种群数量、细菌群落组成、多样性及代谢活性的影响。结果表明,总石油烃(Total Petloleum hydrocarbon/TPH)在灌区干渠和支渠中的积累和分布趋势大体上是上游地区较严重,下游地区较轻,并且与土壤中有机质含量呈显著正相关。在目前的污染程度下,石油污水能够刺激土壤好氧异养细菌(Aerobic heterotrophic bacteria/AHB)和真菌的生长,其数量与TPH含量呈显著正相关。细菌基因多样性与TPH含量呈显著负相关,细菌群落中的优势菌群为变形细菌β-亚群和γ-亚群的菌种。土壤脱氢酶、过氧化氢酶、多酚氧化酶活性和土壤底物诱导呼吸(substrate-induced respiration/SIR)与土壤中TPH含量呈显著正相关,而土壤脉酶活性则与之呈显著负相关。实验室110天不同浓度石油烃胁迫模拟试验结果表明,当石油烃胁迫浓度低于1000mgk扩时可以被定义为轻度污染,土壤中AHB大量增殖,细菌多样性和群落结构可在处理第30天和第50天得到恢复;当石油烃胁迫浓度为5000mg·kg~(-1)-10000mg·kg~(-1)时可以被定义为中度污染,AHB数量显著增加,放线菌和真菌数量显著降低,土壤细菌多样性在培养前巧天显著降低,至培养结束时有逐渐恢复的趋势,细菌群落结构发生明显改变,土壤脱氢酶、多酚氧化酶、脉酶的活性及土壤SIR受到一定程度的抑制,但能够显著刺激土壤过氧化氢酶活性的提高。当石油烃胁迫浓度为10000mg·kg~(-1)-50000mg·kg~(-1)时可以被定义为重度污染,对AHB生长的刺激作用更为显著,土壤细菌多样性在培养前15天显著降低并不可恢复,群落组成与对照差异很大,所有土壤酶和SIR均受到严重抑制。从沈抚灌区上游地区旱田土壤、灌渠底泥和实验室高浓度石油烃胁迫土壤中筛选出了4株TPH生物降解率在60%以上的高效石油烃降解菌并鉴定其归属,这些菌株均能够利用正构烷烃、单环和多环芳烃及环烷烃。

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Advances in genome technology have facilitated a new understanding of the historical and genetic processes crucial to rapid phenotypic evolution under domestication(1,2). To understand the process of dog diversification better, we conducted an extensive genome-wide survey of more than 48,000 single nucleotide polymorphisms in dogs and their wild progenitor, the grey wolf. Here we show that dog breeds share a higher proportion of multi-locus haplotypes unique to grey wolves from the Middle East, indicating that they are a dominant source of genetic diversity for dogs rather than wolves from east Asia, as suggested by mitochondrial DNA sequence data(3). Furthermore, we find a surprising correspondence between genetic and phenotypic/functional breed groupings but there are exceptions that suggest phenotypic diversification depended in part on the repeated crossing of individuals with novel phenotypes. Our results show that Middle Eastern wolves were a critical source of genome diversity, although interbreeding with local wolf populations clearly occurred elsewhere in the early history of specific lineages. More recently, the evolution of modern dog breeds seems to have been an iterative process that drew on a limited genetic toolkit to create remarkable phenotypic diversity.

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Cetaceans produce sound signals frequently. Usually, acoustic localization of cetaceans was made by cable hydrophone arrays and multichannel recording systems. In this study, a simple and relatively inexpensive towed acoustic system consisting of two miniature stereo acoustic data-loggers is described for localization and tracking of finless porpoises in a mobile survey. Among 204 porpoises detected acoustically, 34 individuals (similar to 17%) were localized, and 4 of the 34 localized individuals were tracked. The accuracy of the localization is considered to be fairly high, as the upper bounds of relative distance errors were less than 41% within 173 m. With the location information, source levels of finless porpoise clicks were estimated to range from 180 to 209 dB re 1 mu Pa pp at 1 m with an average of 197 dB (N=34), which is over 20 dB higher than that estimated previously from animals in enclosed waters. For the four tracked porpoises, two-dimensional swimming trajectories relative to the moving survey boat, absolute swimming speed, and absolute heading direction are deduced by assuming the animal movements are straight and at constant speed in the segment between two consecutive locations.

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The aerobic degradation of hexachlorobenzene (HCB) by an acclimated microbial community which isolated from a contaminated site and acclimated in our laboratory was investigated. The enriched microbial community was capable of biodegrading HCB when cultivated in minimal salts medium and supplied HCB as the sole carbon source. The efficiencies of microbial community in the degradation of HCB under different pH and temperatures were examined. The phylogenetic analysis for the nearly complete sequences of 16S rDNA demonstrated that the bacteria assemblage in the microbial community was dominated by Azospirillum and Alcaligenes groups.

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Microcystins are a kind of cyclic hepatoxins produced by many species of cyanobacteria. The toxic effects of microcystins on animals and plants have been well studied. However, the reports about the effects of microcystins on microbial cells are very limited. In present paper, Escherichia coli was undertaken to determine the effect of microcystin-RR. These results suggested that microcystin-RR could prolong the growth of E. coli when exposed to high concentrations of microcystin-RR and cause the accumulation of ROS and induce the oxidant stress for a short time. The antioxidant system protects E. coli from oxidative damage.

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SIMP (source of immunodominant MHC-associated peptides) plays a key rote in N-linked glycosylation with the active site of oligosaccharyltransferase, being the source of MHC-peptides in the MHC I presentation pathway. In the present study, the SIMP gene has been cloned from grass carp Ctenopharyngodon idella by rapid amplification of cDNA ends (RACE). The full length of the cDNA sequence is 4384 bp, including a 1117 bp 5' UTR (untranslated region), a 2418 bp open reading frame, and a 849 bp 3' UTR. The deduced amino acids of the grass carp SIMP (gcSIMP) are a highly conserved protein with a STT3 domain and 11 transmembrane regions. The gcSIMP spans over more than 24,212 bp in length, containing 16 exons and 15 introns. Most encoding exons, except the first and the 15th, have the same length as those in human and mouse. The gcSIMP promoter contains many putative transcription factor binding sites, such as Oct-1, GCN4, YY1, Sp1, Palpha, TBP, GATA-1, C/EBP beta, and five C/EBP alpha binding sites. The mRNA expression of gcSIMP in different organs was examined by real-time PCR. The gcSIMP was distributed in all the organs examined, with the highest level in brain, followed by the level in the heart, liver, gill, trunk kidney, muscle, head kidney, thymus, and the lowest level in spleen. Furthermore, the recombinant gcSIMP has been constructed successfully and expressed in Escherichia coli by using pQE-40 vector, and the polyclonal antibody for rabbit has been successfully obtained, which was verified to be specific. Identification of gcSIMP will help to explore the function in fish innate immunity. (c) 2007 Elsevier Ltd. All rights reserved.