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161.
Livia Handrova Vladimir Kmet 《Journal of environmental science and health. Part. B》2013,48(7):605-614
One of the major global problems in medicine is microbial resistance to antibiotics (antimicrobial resistance) and this has become an increasingly frequent research topic. This study focuses on antimicrobial resistance, phylogenetic and genetic characterization of Escherichia coli from wild birds: ten isolates from eagles (Aquila chrysaetos), nine from goshawks (Accipiter gentilis) and 24 from broilers in the Slovak Republic. Twenty-two strains with presence of int1 gene were selected and examined for the presence or absence of transposon gene (tn3), genes of antibiotic resistance and virulence factors. We detected sequence type (ST) in eagles ST 442 with genes iss, papC, iutA, cvaC, tsh, fyuA, iroN, kps, feoB, sitA, irp2, ireA for virulence factors and tetA, sul1, sul2, dfrA, aadA for antibiotic resistance; in goshawks ST 1011 with iss, papC, fyuA, iroN, feoB, sitA and qnrS1, tetA, sul1, sul2, dfrA, aadA, respectively. These ST types have been found in humans too and should be evaluated further for possible zoonotic potential and transfer of resistance genes from the environment. 相似文献
162.
以秸秆等农业废物为主要原料,添加硝化抑制剂双氰胺(dicyandiamide,DCD)进行静态好氧堆肥实验,设置相同堆肥条件不添加DCD作为空白对照,分析了堆肥过程中各个时期不同处理的pH值、NH4+-N浓度、NO3--N浓度和水溶性有机碳(WSC)理化参数的变化趋势,并应用定量聚合酶链式反应(real-time PCR)技术对参与反硝化过程的功能基因(nirK、nirS和nosZ)丰度随时间的变化情况进行了研究。结果表明,添加DCD明显地改变了堆肥过程的氮素转化,两组堆肥样品的pH值、NH4+-N浓度、NO3--N浓度有显著差异(pnirK基因的抑制效果最显著,同时nirS和nosZ基因因为理化参数的改变而受到了间接影响。 相似文献
163.
污泥臭氧氧化处理过程中活菌抗药基因丰度的消减 总被引:1,自引:0,他引:1
臭氧氧化技术是一种广泛应用的污泥减量技术,然而臭氧处理能否对污泥中的抗生素抗药基因进行有效消减还不清楚。采用单叠氮溴化丙锭(propidium monoazide,PMA)预处理结合定量PCR(qPCR)方法对污泥臭氧减量过程中不同臭氧消耗量下活性污泥活菌中的四环素、氨基糖苷和大环内酯3大类共21种抗药基因的变化进行了研究。结果表明:臭氧氧化可以有效消减活性污泥活菌中21种抗药基因的绝对丰度(每毫升污泥的抗药基因拷贝数),在臭氧消耗量0.31 g·g-1(TSS)情况下抗药基因总量降低了75.44%;尽管绝对丰度下降,污泥臭氧氧化处理过程中大量抗药基因的相对丰度(抗药基因拷贝数与细菌16S rRNA基因拷贝数的比例)逐渐增加,表明臭氧处理后污泥中耐药菌占总活菌比例可能增加,具有一定的抗性传播风险;Ⅰ型整合子是抗药基因水平转移的重要遗传元件,其绝对丰度同样随着臭氧消耗量增加而降低,而相对丰度逐渐上升。 相似文献
164.
Miloš Krist Petr Nádvorník Lenka Uvírová Stanislav Bureš 《Behavioral ecology and sociobiology》2005,59(1):6-11
Females in most bird species engage in extra-pair copulations. Although this behaviour is widespread, benefits for females of doing so are less understood. The most widely accepted hypothesis is that they improve their previous choice of social partner and gain genetic benefits for their offspring. Some evidence for this comes from studies that find that extra-pair young (EPY) have greater fitness than their half-sibs. However, this might be also caused by maternal, non-genetic effect, a possibility that remains largely untested. Here we test whether EPY are laid in larger eggs or eggs laid early in the laying sequence in the collared flycatcher (Ficedula albicollis). The size of eggs bearing EPY and within-pair young (WPY) did not differ, however, EPY were laid in early eggs and consequently hatched earlier than WPY. As hatching asynchrony is a strong determinant of offspring size and survival in many species, including collared flycatcher, our results suggest that a caution is needed when paternal genetic effects are to be inferred from comparison of naturally occurring half-sibs. 相似文献
165.
抗生素的环境残留、生态毒性及抗性基因污染 总被引:64,自引:3,他引:64
抗生素的环境污染与生态毒害问题近年来引起了极大的关注.在总结国内外相关研究基础上,对环境中几种典型抗生素(四环素、土霉素、氯四环素和磺胺类等)的污染源以及在水和土壤环境中的残留与污染水平进行了分析;对抗生素的污染生态毒性最新研究进展给予了评述;对抗生素抗性基因在环境中可能的暴露途径进行了探讨,指出应将抗生素抗性基因作为一类新的环境污染物.鉴于我国抗生素污染的严峻事实,建议应从国家层面上尽快开展有关抗生素环境污染和生态毒害机理的系统研究. 相似文献
166.
A generalized approach for producing,quantifying, and validating citizen science data from wildlife images 总被引:1,自引:0,他引:1 下载免费PDF全文
Alexandra Swanson Margaret Kosmala Chris Lintott Craig Packer 《Conservation biology》2016,30(3):520-531
Citizen science has the potential to expand the scope and scale of research in ecology and conservation, but many professional researchers remain skeptical of data produced by nonexperts. We devised an approach for producing accurate, reliable data from untrained, nonexpert volunteers. On the citizen science website www.snapshotserengeti.org , more than 28,000 volunteers classified 1.51 million images taken in a large‐scale camera‐trap survey in Serengeti National Park, Tanzania. Each image was circulated to, on average, 27 volunteers, and their classifications were aggregated using a simple plurality algorithm. We validated the aggregated answers against a data set of 3829 images verified by experts and calculated 3 certainty metrics—level of agreement among classifications (evenness), fraction of classifications supporting the aggregated answer (fraction support), and fraction of classifiers who reported “nothing here” for an image that was ultimately classified as containing an animal (fraction blank)—to measure confidence that an aggregated answer was correct. Overall, aggregated volunteer answers agreed with the expert‐verified data on 98% of images, but accuracy differed by species commonness such that rare species had higher rates of false positives and false negatives. Easily calculated analysis of variance and post‐hoc Tukey tests indicated that the certainty metrics were significant indicators of whether each image was correctly classified or classifiable. Thus, the certainty metrics can be used to identify images for expert review. Bootstrapping analyses further indicated that 90% of images were correctly classified with just 5 volunteers per image. Species classifications based on the plurality vote of multiple citizen scientists can provide a reliable foundation for large‐scale monitoring of African wildlife. 相似文献
167.
Yuan Meng Weiyi Liu Heidelore Fiedler Jinlan Zhang Xinrui Wei Xiaohui Liu Meng Peng Tingting Zhang 《Frontiers of Environmental Science & Engineering》2021,15(5):104
168.
Brian J. Olsen Russell Greenberg Robert C. Fleischer Jeffrey R. Walters 《Behavioral ecology and sociobiology》2008,63(2):285-294
Over the past two decades, the combination of molecular and field methods has revealed considerable variation in the level
of extrapair fertilizations among socially monogamous birds. Models predicting extrapair young range in scale from a single
population to multiple Orders, and there is no single, unifying theory for these reproductive tactics. We investigated proximate
explanations of extrapair fertilizations in two subspecies of the swamp sparrow, Melospiza georgiana georgiana and Melospiza georgiana nigrescens, across a range of social and environmental conditions. The presence of extrapair young was best predicted by the size of
two male plumage badges (one correlated with parental care and one with territorial aggression) relative to the badge size
of their immediate neighbors, the interaction of these two measures, mean territory size, and the maximum size of the aggression
badge among neighbors. The size of the male’s parental care badge (relative to neighbors) was negatively correlated with the
probability of lost paternity. The relative size of the aggression badge was positively correlated with the presence of extrapair
young when the parental care badge was small and negatively correlated when the badge was large. Controlling for these crown
measures, males with larger territories were less likely to suffer losses in paternity. There was no effect of breeding density,
breeding synchrony, their interaction, subspecies, or weather during the fertile period on the presence of extrapair young.
These results suggest that female preference for males that provide more parental care (or preference for genes that convey
this trait) plays a dominant role in extrapair interactions among swamp sparrows. Models based on female assessments of relative
mate quality offer a promising explanation of patterns in extrapair fertilizations among bird species. 相似文献
169.
Mahmoud Elafify Maha Al-Ashmawy Mohammed Elsherbini Amera Abd El Latif Takashi Okanda 《Journal of environmental science and health. Part. B》2020,55(3):265-272
AbstractFood contaminated with Shiga toxin-producing Escherichia coli (STEC) represents a hazardous public health problem worldwide. Therefore, the present study was performed to elucidate the virulent and antimicrobial resistance characteristics of STEC isolated from milk and dairy products marketed in Egypt. A total of 125 samples (raw market milk, bulk tank milk, Kareish cheese, white soft cheese, and small scale-produced ice cream, 25 each) were collected for determination the prevalence and antimicrobial resistance profiling of STEC. Thirty-six STEC isolates were recovered from milk and dairy products. Serological analysis illustrated that three isolates were E. coli O157:H7 and 33 isolates belonged to different serotypes. Molecular examination indicated that all isolates harboured stx1 and/or stx2 genes, 14 isolates expressed eaeA gene and 3 isolates possessed rfbE gene. Antimicrobial resistance profiling of the isolates was both phenotypically and genetically examined. Interestingly, 31 out of 36 (86.11%) isolates were multidrug-resistant and harboured the extended-spectrum β-lactamase encoding genes, namely, blaCTX-M-15, blaSHV-12 and blaCTX-M-14. Moreover, 12 isolates (33.33%) harboured plasmid-mediated quinolone resistant gene, qnrS. The overall conclusion of the current investigation indicated insufficient hygienic measures adopted during milking, handling, and processing leading to development of pathogenic and multidrug-resistant STEC. 相似文献
170.
Recent theoretical and empirical studies have shown that male dominance is often at odds with female mate preference and that
indirect (genetic) benefits of mate choice may not be related to male dominance. We tested whether female preference corresponded
to male dominance and whether mating with dominant males conveyed benefits to offspring fitness in a small freshwater fish,
the African annual killifish Nothobranchius korthausae (Cyprinodontiformes), a species without parental care. The experimental design used controlled for the effect of male age,
possibility of sperm and egg depletion, and accounted for a potential that females express their preference through maternal
effects by manipulation of egg mass during ovulation. By sequentially mating females with males of known dominance, we found
that female N. korthausae showed no mate preference in terms of egg numbers deposited with respect to male dominance or body size and no congruent
mate preference to specific males was detected. However, males sired offspring with consistently higher hatching success and
the effect was repeatable across individual females. Thus, some males provided females with indirect benefits related to additive
genetic quality (“good genes”) and expressed via increased hatching rate, but this benefit was not related to male dominance
status or body size. 相似文献