Inter-sexual differences in T-cell-mediated immunity of black-headed gull chicks (<Emphasis Type="Italic">Larus ridibundus</Emphasis>) depend on the hatching order

Hatching asynchrony in avian species leads to age and size differences between nestlings within a brood, handicapping last-hatched chicks in the sibling rivalry. Starvation due to this competitive disadvantage has been regarded as the primary cause of an increase in mortality with hatching order. However, for gulls it has also been suggested that disease is the cause of mortality for last-hatched chicks, possibly through reduced immunocompetence and thereby an enhanced susceptibility to infection. In addition, the male-biased mortality reported for several gull species may be related to a higher vulnerability to diseases in males compared to females. To determine the potential influence of the immune system on these mortality patterns, we investigated the T-cell-mediated immunity (CMI) of black-headed gull chicks in relation to hatching order and sex. We found a significant decrease in the CMI with hatching order. This result may be causally related to systematic changes in maternal yolk steroids and carotenoids within the laying sequence. For second-laid eggs, male CMI was significantly lower than female CMI. This is possibly linked to higher plasma levels of testosterone in male embryos which might have an immunosuppressive effect. If so, this effect is masked in eggs of either high (first egg) or low (last egg) quality. Chicks with low CMI showed enhanced mortality rates. Thus the differences in immune response are likely to contribute to the observed mortality patterns. However, hatching order significantly affected mortality independently of CMI, suggesting that competitive disadvantage due to hatching asynchrony is also important.Communicated by M. Webster     

A pipeline of tweets: environmental movements’ use of Twitter in response to the Keystone XL pipeline

Social movements often amalgamate otherwise diffuse public political interests. In recent years, social media use has allowed both groups and individuals to engage with political issues both online and offline. How do organizations use Twitter to mobilize networked publics? To what extent do groups promote both ‘connective action’ online and traditional activism offline? How do their strategies differ according to whether they seek to promote or combat the status quo? And how do they balance encouraging and reinforcing individualized expression through group messaging? The ways pro-Keystone XL pipeline and anti-Keystone XL groups differed in their Keystone-related action on Twitter from January 2010 until October 2014 are analyzed. Boolean searching and Natural Language processing are used to analyze more than three million tweets. The results demonstrate that the frames within Twitter conversations have significant implications for how communities understand, develop, and mobilize around environmental issues.     

Elite cues,media coverage,and public concern: an integrated path analysis of public opinion on climate change, 2001–2013

To analyze the factors affecting US public concern about the threat of climate change between January 2002 and December 2013, data from 74 separate surveys are used to construct quarterly measures of public concern over global climate change. Five factors should account for changes in levels of concern: extreme weather events, public access to accurate scientific information, media coverage, elite cues, and movement/countermovement advocacy. Structural equation modeling indicates that elite cues, movement advocacy efforts, weather, and structural economic factors influence the level of public concern about climate change. While media coverage exerts an important influence, it is itself largely a function of elite cues and economic factors. Promulgation to the public of scientific information on climate change has no effect. Information-based science advocacy has had only a minor effect on public concern, while political mobilization by elites and advocacy groups is critical in influencing climate change concern.     

“引江济太”过程中塑化剂类污染物的输入特征和环境健康风险评价

为了解\"引江济太\"过程中塑化剂类污染物对贡湖的输入特征,于2013年8月对14个采样点的7种邻苯二甲酸酯类化合物(PAEs)的浓度进行采样分析,并通过美国环保署(USEPA)推荐的方法,对其环境风险进行评价.结果表明:各采样点邻苯二甲酸二丁酯(DBP)和邻苯二甲酸二环己酯(DCHP)均有检出,除采样点10、11和12外,邻苯二甲酸二乙酯(DEP)也有检出,其余4种均未检出,长江引水经望虞河进入贡湖后,DEP、DBP和DCHP浓度均有不同程度的降低,且其最高浓度均出现在望虞河长江引水处(采样点1),说明在引水过程中长江水对望虞河有明显的PAEs输入,而贡湖锡东水厂DEP浓度高于贡湖其他采样点,南泉水厂DBP和DCHP浓度高于贡湖其他采样点,金墅湾水厂PAEs浓度总体处于较低水平.环境健康风险评价结果显示:DEP的最大非致癌风险值为3.91×10-8 a-1,未超过国际组织规定范围,而DBP的最大非致癌风险值为1.17×10-5 a-1,超过英国皇家协会RS规定的1×10-6 a-1,但均对人体无明显非致癌危害.     

枯草芽孢杆菌漆酶与阴离子型聚丙烯酰胺微观作用机理

阴离子型聚丙烯酰胺（HPAM）常用于煤泥水的澄清处理,产生大量的含聚污水将对选煤厂周边环境造成不利影响. 为探究漆酶降解HPAM的微观作用机理,采用对接模拟了HPAM及其脱氨产物聚丙烯酸（PAA）结构模型与枯草芽孢杆菌漆酶（Lac）的结合,根据-CDOCKER_ Energyscore打分最高原则筛选出Lac的最适底物,然后对该最适复合物分别进行基于亲和力虚拟突变和不同温度下的分子动力学（MD）模拟. 结合模式分析表明,Lac对HPAM-3享有最高亲和力,且其结合最好,因此HPAM-3是该酶的最适底物;HPAM比PAA易被Lac降解;Lac可容纳一定碳链长度的HPAM和PAA. 相互作用分析表明,Lac-HPAM-3亲和力最大主要原因是盐桥;TYR133通过形成氢键以稳定Lac-HPAM-2、Lac-HPAM-3和Lac-HPAM-4,而ARG487通过形成疏水以稳定所有的酶-底物复合物. 基于亲和力虚拟突变分析表明,TYR118、TYR133、ARG487和LYS135是Lac降解HPAM-3的关键残基;LYS135和ARG487分别通过形成盐桥和疏水来最大限度地影响酶同底物的亲和力. MD分析表明,Lac-HPAM-3在298 K时总相互作用能、酶骨架RMSD及所有残基RMSF皆最低,因此该复合物在298 K时结合稳定性最佳;308 K时由于酶骨架RMSD最大,导致底物偏离最初对接位置,因此Lac-HPAM-3在308 K时结合稳定性最差. 这些数据为揭示HPAM酶降解过程奠定基础,为将来突变试验来改造酶提供位点支持.     

砷对绿藻的毒性效应及氧化还原条件的影响

选择绿藻中耐毒品种莱茵衣藻(Chlamydomonas reinhardtii)为研究对象,分析三价砷加入对其体系氧化还原条件的影响,研究代表性绿藻莱茵衣藻C. reinhardtii对水体三价砷毒性的响应.结果表明,光照或黑暗条件下莱茵衣藻C. reinhardtii的生长都会使pH升高,氧化还原电位(Eh)减小.根据pH-Eh分析可知,水体三价砷As(Ⅲ)大部分以H2AsO3-存在,H2AsO3-加入后pH升高和Eh减小趋势更为明显,并随其浓度增大,Eh会出现缓慢上升趋势.同时,pH与Eh变化也会影响砷对藻类的毒效应,当pH值为10.0-10.5,Eh为-143- -136 mV时,三价砷浓度增大对藻类生长速率没有明显影响,但当pH值为9.5-10.1,Eh为-156- -143 mV时,三价砷浓度增大会明显降低了藻类生长速率.     

An Evaluation of Selenium Concentrations in Water, Sediment, Invertebrates, and Fish from the Republican River Basin: 1997–1999

The Republican River Basin of Colorado,Nebraska, and Kansas lies in a valley which contains PierreShale as part of its geological substrata. Selenium is anindigenous constituent in the shale and is readily leached intosurrounding groundwater. The Basin is heavily irrigated throughthe pumping of groundwater, some of which is selenium-contaminated, onto fields in agricultural production. Water,sediment, benthic invertebrates, and/or fish were collected from46 sites in the Basin and were analyzed for selenium to determinethe potential for food-chain bioaccumulation, dietary toxicity,and reproductive effects of selenium in biota. Resultingselenium concentrations were compared to published guidelines orbiological effects thresholds. Water from 38% of the sites (n = 18) contained selenium concentrations exceeding 5 g L^-1, which is reported to be a high hazard for selenium accumulation into the planktonic food chain. An additional 12 sites (26% of the sites) contained selenium in water between 3–5 g L^-1, constituting a moderate hazard. Selenium concentrations in sedimentindicated little to no hazard for selenium accumulation fromsediments into the benthic food chain. Ninety-five percent ofbenthic invertebrates collected exhibited selenium concentrationsexceeding 3 g g^-1, a level reported as potentially lethal to fish and birds that consume them. Seventy-five percent of fish collected in 1997, 90% in 1998, and 64% in 1999 exceeded 4 g g^-1selenium, indicating a high potential for toxicity andreproductive effects. However, examination of weight profilesof various species of collected individual fish suggestedsuccessful recruitment in spite of selenium concentrations thatexceeded published biological effects thresholds for health andreproductive success. This finding suggested that universalapplication of published guidelines for selenium may beinappropriate or at least may need refinement for systems similarto the Republican River Basin. Additional research is needed todetermine the true impact of selenium on fish and wildliferesources in the Basin.     

Using environmental stressor information to predict the ecological status of Maryland non-tidal streams as measured by biological indicators

In Maryland, U.S., an interim framework has recentlybeen developed for using biologically based thresholds, or `biocriteria', to assess the health of nontidal streams statewide at watershed scales. The evaluation of impairment is based on indices of biological integrity from the Maryland Biological Stream Survey (MBSS). We applied logistic regression to quantify how the biotic integrity of streams at a local scale is affected by cumulative effects resulting from catchment land uses, point sources, and nearby transmission line rights-of-way. Indicators for land use were developed from the remote sensing National Land Cover Data and applied at different scales. We determined that the risk of local impairment in nontidal streams rapidly increases with increased urban land use in the catchment area. The average likelihood of failing biocriteria doubled with every 10% points increment in urban land, thus an increase in urban land use from 0 to 20% quadruples the risk of impairment. For the basins evaluated in this study, catchments with more than 40–50% urban land use had greater than 80% probability of failing biocriteria, on average. Inclusion of rights-of-way and point sources in the model did not significantly improve the fit for this data set, most likely because of their low numbers. The overall results indicate that our predictive modeling approach can help pinpoint stream ecosystems experiencing or vulnerable to degradation.     

2种典型碳纳米管低浓度暴露诱发锦鲫组织损伤与肝脏氧化损伤效应研究

采用半静态染毒方法,研究了单壁碳纳米管（SWCNT）和羟基化多壁碳纳米管（MCWNT-OH）对锦鲫抗氧化防御系统的影响。 结果表明,锦鲫经28d不同质量浓度的SWCNT和MWCNT-OH（0,10,100和1000μg/L）暴露后,暴露组14d鳃组织切片检查发现出现鳃动脉瘤、鳃细胞水肿、畸形生长等病理症状;然而在2种碳纳米管低浓度暴露下,锦鲫的肝脏切片没有观察到损伤,高浓度时肝脏有轻微空泡损伤。暴露期间锦鲫没有死亡,随着暴露天数的增加,2种碳纳米管都能对SOD和CAT酶产生抑制作用,高浓度组抑制明显,肝脏抗氧化系统受到损伤。指出,虽然碳纳米管的毒性较低,但其长期暴露对鱼类的影响仍需进一步关注。     

Review of the effects of in-stream pipeline crossing construction on aquatic ecosystems and examination of Canadian methodologies for impact assessment

Pipeline crossing construction alters river and stream channels, hence may have detrimental effects on aquatic ecosystems. This review examines the effects of crossing construction on fish and fish habitat in rivers and streams, and recommends an approach to monitoring and assessment of impacts associated with these activities. Pipeline crossing construction is shown to not only compromise the integrity of the physical and chemical nature of fish habitat, but also to affect biological habitat (e.g., benthic invertebrates and invertebrate drift), and fish behavior and physiology. Indicators of effect include: water quality (total suspended solids TSS), physical habitat (substrate particle size, channel morphology), benthic invertebrate community structure and drift (abundance, species composition, diversity, standing crop), and fish behavior and physiology (hierarchy, feeding, respiration rate, loss of equilibrium, blood hematocrit and leukocrit levels, heart rate and stroke volume). The Before-After-Control-Impact (BACI) approach, which is often applied in Environmental Effects Monitoring (EEM), is recommended as a basis for impact assessment, as is consideration of site-specific sensitivities, assessment of significance, and cumulative effects.