Horizontal and vertical gene transfer drive sediment antibiotic resistome in an urban lagoon system

Rapid urbanization has resulted in pervasive occurrence of antibiotic resistance genes (ARGs) in urban aquatic ecosystems. However, limited information is available concerning the ARG profiles and the forces responsible for their assembly in urban landscape lagoon systems. Here, we employed high-throughput quantitative PCR (HT-qPCR) to characterize the spatial variations of ARGs in surface and core sediments of Yundang Lagoon, China. The results indicated that the average richness and absolute abundance of ARGs were 11 and 53 times higher in the lagoon sediments as compared to pristine reference Tibetan lake sediments, highlighting the role of anthropogenic activities in ARG pollution. Co-occurrence network analysis indicated that various anaerobic prokaryotic genera belonging to Alpha-, Deltaproteobacteria, Bacteroidetes, Euryarchaeota, Firmicutes and Synergistetes were the potential hosts of ARGs. The partial least squares-path modeling (PLS-PM) analysis revealed positive and negative indirect effects of physicochemical factors and heavy metals on the lagoon ARG profiles, via biotic factors, respectively. The horizontal (mediated by mobile genetic elements) and vertical (mediated by prokaryotic communities) gene transfer may directly contribute the most to drive the abundance and composition of ARGs, respectively. Furthermore, the neutral community model demonstrated that the assembly of sediment ARG communities was jointly governed by deterministic and stochastic processes. Overall, this study provides novel insights into the diversity and distribution of ARGs in the benthic habitat of urban lagoon systems and underlying mechanisms for the spread and proliferation of ARGs.     

两种粒径纳米银对Nitrosomonas europaea的毒性效应

为明晰不同粒径纳米银（AgNPs）对欧洲亚硝化毛杆菌（Nitrosomonas europaea）的毒性效应,采用室内培养方式,探究10nm和50nm的AgNPs对N.europaea生长、氮转化能力、细胞结构、活性氧生成和功能基因表达的影响.结果表明,AgNPs暴露抑制N.europaea生长,随着暴露时间的延长,细菌生长抑制率增加,在4h达到最大值;培养基中NH₄⁺向NO₂^-转化速率减缓,N.europaea的铵态氮转化能力降低;扫描电镜（SEM）图像显示AgNPs造成部分细菌表面塌陷且有孔洞,细胞膜受损严重;透射电镜（TEM）图像显示AgNPs造成细菌内部核物质消融,细胞质膜界限模糊;流式细胞仪（FCM）检测发现AgNPs增加细胞内活性氧的生成;qRT-PCR技术对AgNPs暴露后N.europaea功能基因amoA、hao、merA表达进行测定,发现AgNPs抑制N.europaea功能基因的转录表达.综上所述,AgNPs通过与细胞膜相互作用和产生氧化应激损伤N.europaea,抑制amoA和merA的表达,进而影响铵态氮转化过程,且小粒径AgNPs的毒性强于大粒径.     

南岳古镇景观基因的居民感知特征及影响因素

以南岳古镇为研究对象,在识别景观基因的基础上,从建筑特征、形态布局和参考环境三个尺度,物质形态、功能作用和文化意义三个维度,以及颜色、形状、范围和建造年代四个形态要素等角度进行了问卷和访谈调查.结果发现,南岳大庙、环境尺度、物质形态和形状因素感知度最高,方形布局、布局尺度、物质形态和文化意义感知度最低;年龄、职业、教育程度、居住时间是影响古镇景观基因居民感知的因素,性别只在景观基因尺度有影响.     

基于QMEC分析的青藏高原不同类型冰川前缘地土壤微生物功能潜力

微生物通过多种功能代谢过程主导着因气候变暖裸露的冰川前缘地土壤元素的地球化学循环.以青藏高原的海洋型冰川、亚大陆型冰川和极大陆型冰川的前缘地土壤为研究对象,分析不同类型冰川前缘地土壤的微生物功能特征.依次选择玉龙冰川、天山乌鲁木齐1号冰川和老虎沟12号冰川作为三类冰川的典型代表,采用高通量功能基因芯片(QMEC)检测土壤微生物的功能基因特征.结果表明,在三类冰川前缘地土壤中,半纤维素降解基因和还原型乙酰辅酶A途径相关的碳固定基因丰度最高,三者主要的氮功能基因和氨化作用有关,磷、硫功能基因则主要与有机磷矿化过程和硫氧化过程相关.其中,水热条件较好的海洋型冰川的微生物功能基因的种类与丰度最高,其次为环境较为干燥的极大陆型冰川.三类冰川前缘地土壤的微生物功能基因结构的显著差异,证实了地理环境差异对微生物功能特征的影响,也为不同类型冰川前缘地土壤微生物的功能及其介导的元素地球化学循环研究提供了基础.     

噬菌体编码的抗生素抗性基因研究进展

噬菌体作为地球上丰度最高的生物体,对于全球生态系统的微生物群落组成与动态,生物地球化学循环和细菌进化等都具有重要作用,但噬菌体对抗生素抗性的贡献还所知甚少.通过宏基因组测序和定量PCR等技术,发现了海洋,河流,土壤,动物肠道等环境的噬菌体基因组中存在多种耐药基因(antibiotic resistance genes,ARGs).因此,噬菌体及其介导的转导作用可能对ARGs的富集扩散发挥着重要作用.本文综述了不同环境介质的噬菌体基因组中ARGs的分布特征以及噬菌体介导的ARGs水平转移的研究进展,同时展望了为阐明噬菌体对抗生素抗性贡献需要解决的科学问题.本文将为了解噬菌体在ARGs传播扩散中的作用以及扩展对可移动抗性组的认知奠定基础.     

Public views about editing genes in wildlife for conservation

Developments in CRISPR-based gene-editing technologies have generated a growing number of proposals to edit genes in wildlife to meet conservation goals. As these proposals have attracted greater attention, controversies have emerged among scientists and stakeholder groups over potential consequences and ethical implications of gene editing. Responsible governance cannot occur without consulting broader publics, yet little effort has been made to systematically assess public understandings and beliefs in relation to this new area of applied genetic engineering. We analyzed data from a survey of U.S. adults (n = 1600), collected by YouGov, and that examined respondents’ concerns about gene editing in animal and plant wildlife and how those concerns are shaped by cultural dispositions toward science and beliefs about the appropriateness of intervening in nature at the genetic level. On average, respondents perceived more risk than benefit in using these tools. Over 70% agreed that gene editing in wildlife could be “easily used for the wrong purposes.” When evaluating the moral acceptability of gene editing in wildlife, respondents evaluated applications to improve survival in endangered wildlife as more morally acceptable than applications to decrease abundance in a population or eliminate a population. Belief in the authority of scientific knowledge was positively related to favorable views of the benefits, risks, and moral acceptability of editing genes in wildlife. The belief that editing genes in wildlife inappropriately intervenes in nature predicted relatively more concern about risks and moral acceptability and skepticism about benefits. Given high levels of concern and skepticism about gene editing in wildlife for conservation among the U.S. public, a take-it-slow approach to making decisions about when or whether to use these tools is advisable. Early opinions, including those uncovered in this study, are likely to be provisional. Thus, consulting the public should be an ongoing process.     

Conservation practitioners’ understanding of how to manage evolutionary processes

Both academics and practitioners consider a lack of knowledge about evolutionary theory to be a general barrier to effectively managing genetic diversity. However, it is challenging to judge practitioners’ level of understanding and how this influences their management decisions. Knowledge built through experience may be difficult for practitioners to articulate, but could nonetheless result in appropriate management strategies. To date, researchers have assessed only the explicit (formal) knowledge practitioners have of evolutionary concepts. To explore practitioners’ understanding of evolutionary concepts, it is necessary to consider how they might apply explicit and implicit knowledge to their management decisions. Using an online survey, we asked Australian practitioners to respond to 2 common management scenarios in which there is strong evidence that managing genetic diversity can improve outcomes: managing small, isolated populations and sourcing seeds for restoration projects. In describing their approach to these scenarios, practitioners demonstrated a stronger understanding of the effective management of genetic diversity than the definitions of the relevant concepts. However, their management of genetic diversity within small populations was closer to best practice than for restoration projects. Moreover, the risks practitioners described in implementing best practice management were more likely to affect their approach to restoration than translocation projects. These findings provide evidence that strategies to build the capacity of practitioners to manage genetic diversity should focus on realistic management scenarios. Given that practitioners recognize the importance of adapting their practices and the strong evidence for the benefits of actively managing genetic diversity, there is hope that better engagement by evolutionary biologists with practitioners could facilitate significant shifts toward evolutionarily enlightened management.     

Targeted gene flow for conservation

Anthropogenic threats often impose strong selection on affected populations, causing rapid evolutionary responses. Unfortunately, these adaptive responses are rarely harnessed for conservation. We suggest that conservation managers pay close attention to adaptive processes and geographic variation, with an eye to using them for conservation goals. Translocating pre‐adapted individuals into recipient populations is currently considered a potentially important management tool in the face of climate change. Targeted gene flow, which involves moving individuals with favorable traits to areas where these traits would have a conservation benefit, could have a much broader application in conservation. Across a species’ range there may be long‐standing geographic variation in traits or variation may have rapidly developed in response to a threatening process. Targeted gene flow could be used to promote natural resistance to threats to increase species resilience. We suggest that targeted gene flow is a currently underappreciated strategy in conservation that has applications ranging from the management of invasive species and their impacts to controlling the impact and virulence of pathogens.     

广州河涌水体中食蚊鱼肝脏性激素相关基因的表达水平研究

应用食蚊鱼细胞色素P450芳香化酶基因(CYP19α)、卵黄蛋白原基因(VTGα)和雌/雄激素受体基因(ERα/ARα)m RNA转录水平为指标,评价广州海珠涌和黄埔涌食蚊鱼受环境激素物质干扰产生雌/雄性化效应的现状。结果显示,海珠涌宝岗大道段(BG)、洪德路段(HD)和黄埔涌赤岗路段(CG)、苗艺路段(MY)采样点雌鱼性腺CYP19αm RNA表达水平显著降低。雌鱼肝脏VTGαm RNA的表达水平在夏冬两季CG点都显著升高,但在BG、HD和MY点的表达水平在冬季则显著下降;夏冬两季雌鱼雄激素受体ARαm RNA表达水平在各点都显著升高。雄鱼性腺CYP19αm RNA表达水平在各点都无明显差异,但CG点在夏季显著升高,而MY点在冬季则显著下降;雄鱼肝脏VTGα和雌激素受体ERαm RNA表达水平分别在各点都显著升高,但夏季MY点和冬季HD、MY各点无明显差异。结果表明,雌性食蚊鱼的VTGα和CYP19α基因受到不同程度的抑制,ERα较对照REF明显升高,表现出雄激素效应;雄性食蚊鱼VTGα和ERα转录水平较对照REF显著升高,CYP19α基因无显著性差异,表现出雌激素效应。生活在广州海珠涌和黄埔涌中的食蚊鱼受雌/雄激素物质干扰明显,表明河涌中环境激素污染严重。     

悬浮物对褐牙鲆抗氧化酶活性及相关基因表达的影响

为探究褐牙鲆(Paralichthys olivaceus)幼鱼抗氧化系统酶活力及相关基因表达在悬浮物胁迫下的变化情况,设计了浓度为5 000、10 000 mg·L-1悬浮物水体对褐牙鲆(14.53 cm±1.58 cm)肌肉、肝脏、鳃及血液总超氧化物歧化酶(T-SOD)、谷胱甘肽转移酶(GST)、过氧化氢酶(CAT)酶活力及SOD2、GST、CAT的mRNA转录水平表达变化情况。结果显示:在悬浮物胁迫24 h或者48 h时,4种组织3种酶活力具有升高的趋势(P0.05);4种组织的T-SOD酶活力在96 h均高于对照组(P0.05),肌肉、鳃丝及血液中SOD2基因相对表达量96 h实验组低于对照组(P0.05);肌肉中CAT酶活力呈现先升高再降低趋势,鳃中CAT基因相对表达量呈现先降低、再升高、再降低的趋势;肝脏、鳃、血液中GST酶活力在悬浮物胁迫下呈现升高趋势,4种组织GST基因相对表达量在12~24 h时呈现升高趋势。研究表明:悬浮物对褐牙鲆抗氧化酶活力及相关基因的表达具有一定的影响,血液中3种酶活力变化幅度最大,鳃中3种基因相对表达水平变化幅度最大,这与血液及鳃参与呼吸作用过程有关;抗氧化酶活性及基因相对表达变化趋势并不完全一致。本研究可为揭示褐牙鲆应对悬浮物胁迫的耐受机制及褐牙鲆耐悬浮物品种选育提供基础数据。