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771.
两座污水处理系统中细胞态和游离态抗生素抗性基因的丰度特征 总被引:2,自引:4,他引:2
为探究污水处理系统中抗生素抗性基因(ARGs)、特别是胞外游离态ARGs的赋存特征,本研究选取生活污水处理系统和工业废水处理系统各一座,采用荧光定量PCR对细胞态及游离态ARGs丰度变化开展研究.在生活污水处理系统M中,进水sulⅡ、tet C、bla PSE-1和erm B这4种ARGs细胞态的绝对丰度均大幅高于游离态的绝对丰度,生物处理未对抗生素抗性菌(ARBs)产生富集效应;MBR的超滤膜有效削减了水中细胞态和游离态DNA,最终ARGs的总去除率为2.54~4.95 logs.在焦化废水处理系统C中,生物处理对携带sulⅡ的ARBs产生了富集效应,但游离态sulⅡ的相对丰度和绝对丰度均有所降低;其后混凝-砂滤工艺使水中细胞态和游离态sulⅡ的绝对丰度分别出现了下降和上升,游离态sulⅡ在总sulⅡ中的比例从生物处理出水中的0.05%,上升到混凝-砂滤出水中的1.33%,并在25℃恒温避光静置5d后进一步上升至9.31%.ARBs深度去除及残留细胞裂解,使污水处理系统出水中游离ARGs在总ARGs中的比例有所上升.游离态ARGs介导ARGs在污水处理系统出水受纳环境中的传播扩散风险有待后续研究进行深入评估. 相似文献
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人体颊黏膜细胞彗星实验方法学研究 总被引:8,自引:0,他引:8
为探索一种简便、直接检测环境诱变物对人体靶细胞遗传毒性的方法,笔者以甲醛作为染毒剂,对人体口腔颊黏膜细胞彗星实验的染毒时间、染毒温度和2种用于检测交联作用的方案进行了研究。结果显示:经7 5μmol L甲醛37℃染毒30和60min后,DNA的断裂程度较染毒15min更大;而经该浓度甲醛在4,23和37℃下染毒30min后均可引起DNA的断裂,但37℃下染毒对DNA的断裂作用更大。在2种应用于检测交联作用的方案中,加大电泳条件的交联检测方案还可检测兼具交联和断裂效应的诱变物。 相似文献
774.
Effects of plant species coexistence on soil enzyme activities and soil microbial
community structure under Cd and Pb combined pollution 总被引:5,自引:1,他引:5
The relationship between plant species coexistence and soil microbial communities under heavy metal pollution has attracted much
attention in ecology. However, whether plant species coexistence could o set the impacts of heavy metal combined pollution on soil
microbial community structure and soil enzymes activities is not well studied. The modified ecological dose model and PCR-RAPD
method were used to assess the e ects of two plant species coexistence on soil microbial community and enzymes activities subjected
to Cd and Pb combined stress. The results indicated that monoculture and mixed culture would increased microbe populations under
Cd and Pb combined stress, and the order of sensitivity of microbial community responding to heavy metal stress was: actinomycetes
> bacteria > fungi. The respirations were significantly higher in planted soil than that in unplanted soil. The plant species coexistence
could enhance soil enzyme activities under Cd and Pb combined. Furthermore, planted soil would be helpful to enhance soil genetic
polymorphisms, but Cd and Pb pollution would cause a decrease on soil genetic polymorphisms. Mixed culture would increase
the ecological dose 50% (ED50) values, and the ED50 values for soil enzyme activities decreased with increasing culture time. The
dehydrogenase was most sensitive to metal addition and easily loses activity under low dose of heavy metal. However, it was di cult
to fully inhibit the phoshpatase activity, and urease responded similarly with phosphatase. 相似文献
775.
776.
环境DNA技术是近几年出现的新兴环境生态监测技术,为研究环境变量对表层沉积物中环境DNA变化的影响,通过小试实验模拟海水环境并以日本大螯蜚作为目标生物,引入4组不同的生物丰度,运用环境DNA技术研究了表层沉积物中环境DNA含量变化与周边环境变量的关系。在小试装置中养殖日本大螯蜚4 d后全部取出,之后启动实验。在实验启动后的第0、6、12、18、24、72、144、264、384小时进行取样,提取出的环境DNA片段含量通过实时荧光进行定量PCR检测。结果表明,表层沉积物中的环境DNA在源生物移除后72 h内降低至较低含量水平,与水体中的环境DNA有较为相似的变化特征。通过广义线性回归分析,发现环境DNA降解速率与水质盐度呈显著负相关(P=0.000 5),与pH呈显著正相关(P=0.04),说明表层沉积物中的环境DNA对于周边环境变化具有一定指示意义。上述结果为进一步推动环境DNA技术的应用及其对环境变量影响作用的深入研究提供参考。 相似文献
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780.
The mating frequency of queens was estimated for eight attine ant species, Myrmicocrypta ednaella, Apterostigma mayri, Cyphomyrmex costatus, C. rimosus (four lower attines), Trachymyrmex isthmicus, Serico-myrmex amabalis, Acromyrmex octospinosus and Atta colombica (four higher attines), and correlated to colony size, worker polyethism, and sex ratio. Mating frequency was calculated from
within-colony relatedness estimated by CAP-PCR DNA fingerprinting. Most queens of lower attines and T. isthmicus mated with only one male, while those of the three higher attines mated with multiple males. Mating frequency was positively
correlated with colony size. Polyethism among workers was dependent on worker age in lower attines but on body size in higher
attines, suggesting some correlation between mating frequency (i.e., within-colony gene diversity) and caste complexity. The
sex ratio was biased toward females in species where the mating frequency equaled one, but toward males in species where the
mating frequency was greater than two. Changing in nest site from ground surface to deep underground may have facilitated
the evolution of large colony size in Attini, and this may have resulted in the evolution of polyandry (a queen mates with
multiple males). With the evolution of polyandry in higher attines, Atta and Acromyrmex in particular have generated high genetic diversity within their colonies and complex social structures.
Received: 26 October 1999 / Revised: 25 May 2000 / Accepted: 24 June 2000 相似文献