Compatible intracellular ion composition of the host improves carbon assimilation by Zooxanthellae in mutualistic symbioses

Cytosymbiotic algae within the host's plasma are exposed to completely different ionic conditions than microalgae living in the sea. The altered ionic gradients, in particular, could be the reason for higher in hospite carbon assimilation levels. To study the effect of varying extracellular ionic conditions on isolated zooxanthellae, their photosynthetic capacity in pure seawater was compared to that in a test medium in which the concentrations of the major inorganic ions, the pH and the osmolality were adjusted to the conditions measured in the host cytoplasm. In this test medium the ratio between oxygen evolution and carbon fixation was 1.2:1.0; in contrast, zooxanthellae in the hyperionic seawater medium showed a comparatively higher oxygen production (2.6:1.0). These results are attributed to a higher energy demand for ion regulation of the isolated algae in the hyperionic medium. Isolated cytosymbionts in seawater need more energy both for the readjustment to the original intracellular ion concentration within the host cell and also for the maintenance of a much steeper gradient during incubation under hyperionic conditions outside the host. The particular intracellular ion concentration of the host cells could have been a decisive evolutionary factor for the very successful establishment of the mutualistic symbioses between anthozoans and dinoflagellates more than 200 million years ago.     

The effect of metapleural gland secretion on the growth of a mutualistic bacterium on the cuticle of leaf-cutting ants

In Acromyrmex octospinosus leaf-cutting ants the metapleural glands produce an array of antibiotic compounds that serve as a general defence against unwanted microbes on the cuticle. Leaf-cutting ants also grow mutualistic Pseudonocardiaceae bacteria on their cuticle that produce antibiotics controlling a microfungal parasite of their fungus gardens. Interaction between this bacterium and gland secretion therefore seems unavoidable. We document the typical development of bacterial growth on the cuticle of young major workers, show that growth starts a few days after eclosion, and that the maximal cover is reached after 2–3 weeks and gradually declines when workers mature. Experimental closure of the metapleural glands had no effect on the initial exponential growth phase of the bacterium, but significantly reduced the cover during the decline phase. The age-dependent abundance of the bacterium and its partial dependence on metapleural gland secretion support the hypothesis that the abundance of this mutualist is actively regulated.     

现阶段中国农地利用专业化的主要限制因素

中国农地利用专业化发展缓慢,落后于西方发达国家,成为其农产品国际竞争力不足的一个重要影响因素。对其原因,目前学术界仍存争议,尚无令人信服的结论。论文利用1991—2013年全国、省域,以及2001—2013年县域（杭嘉湖地区）3个尺度的种植面积数据,采用赫芬达尔专业化指数（SHHI）,并结合关联政策的资料分析,重点检验主粮生产对农地利用专业化的主控性和限制性,探讨现阶段中国农地利用专业化的主要限制因素。结果显示：1）现阶段中国农地利用专业化水平受主粮播种面积占比的控制,全国和省域尺度上,无论时间维度还是空间维度,两变量均在5%以下显著性水平上呈正相关关系;县域尺度上,两变量在空间维度上呈显著高度正相关,时间维度上76%的区县呈显著正相关。2）粮食生产保护政策约束了粮食作物的退出,压缩了非粮作物的增长空间,限制了农地利用专业化的发展。结果表明,国家对粮食（尤其是主粮）生产的保护是现阶段中国农地利用专业化的主要限制因素。因此,论文提出转变“粮食安全”观、优化农业生产布局等促进农地利用专业化的政策建议。     

Effect of heavy metals on soil nematode communities in the vicinity of a metallurgical factory

The influence of Cu and Zn on soil nematode communities was examined along a pollution gradient with increasing distance from a metallurgical factory. Total and available heavy metal contents were used to study the effects of heavy metals on nematode abundance, trophic groups and ecological indices. The results demonstrated significant correlations between the number of total nematodes, bacterivores, plant-parasites and the total and available heavy metals. Bacterivores and plant-parasites were the dominant trophic groups. Significant differences in different sampling sites were found only in the number of bacterivores（P〈0.01）. The Shannon-Weaver diversity index（W）, trophic diversity index（TD）, evenness index（J＇） and dominance index（λ） were found to be sensitive to soil pH and C/N ratios. Significant correlations were found between the total nematodes （TNEM）, some genera （A crobeloides, Aphelenchoides, Cephalobus, Ditylenchus, Mesorhabditis, Tetylenchus and Tylenchus） and distance from the factory.     

Confirmation of combinational effects of calcium with other metals in a paper recycling mill effluent on nematode lifespan with toxicity identification evaluation method

We used toxicity identification evaluation (TIE) method to confirm the combinational e ects of identified toxic metals in a paper recycling mill e uent in inducing the decreased lifespan in nematode Caenorhabditis elegans. Exposure to Ca + Al caused more severely decreased lifespan than that exposed to Ca, or Al; and exposure to Ca + Fe induced more severely decreased lifespan than that exposed to Ca, or Fe. Exposure to Ca+Al+Fe caused more severely decreased lifespan than that exposed to Ca, or Ca+Fe. Moreover, the baseline toxicity on lifespan was doubled by doubling the concentration of combined metals (Ca+Al+Fe) in spiking test in original e uent (oe), and lifespan defects in oe+Ca+Al+Fe exposed nematodes were more severe than that in Ca+Al+Fe exposed nematode. Therefore, Ca+Al+Fe exposure may largely explain the formation of decreased lifespan induced by the examined industrial e uent. Furthermore, the observed reduction of lifespan induced by the combination of high level of Ca with other metals may be at least partially independent of the insulin-like pathway.     

Toxicity evaluation in a paper recycling mill effluent by coupling bioindicator of aging with the toxicity identification evaluation method in nematode Caenorhabditis elegans

Toxicity identification evaluation (TIE) can be used to determine the specific toxicant(s) in industrial effluents.In the current study,the authors have attempted to combine the advantages of the model organism,Caenorhabditis elegans,with the virtues of the TIE technique,to evaluate and identify the toxicity on aging from a paper recycling mill effluent.The results indicate that only the toxicities from mixed cellulose (MC) filtration and EDTA treatment are similar to the baseline aging toxicity,suggesting ...     

Toxicity evaluation in a paper recycling mill e uent by coupling bioindicator of aging with the toxicity identification evaluation method in nematode Caenorhabditis elegans

Toxicity identification evaluation (TIE) can be used to determine the specific toxicant(s) in industrial e uents. In the current study, the authors have attempted to combine the advantages of the model organism, Caenorhabditis elegans, with the virtues of the TIE technique, to evaluate and identify the toxicity on aging from a paper recycling mill e uent. The results indicate that only the toxicities from mixed cellulose (MC) filtration and EDTA treatment are similar to the baseline aging toxicity, suggesting that the suspect toxicants inducing aging toxicity may largely be the heavy metal substances in this industrial e uent. Examination of the accumulation of intestinal autofluorescence in adult animals further confirms that the short lifespans are actually due to accelerated aging. In addition, exposure to fractions of EDTA manipulations cannot result in severe defects of reproduction and locomotion behaviors in C. elegans. Moreover, high levels of Ca, Al, and Fe in the e uent may account for the severe toxicity on aging of exposed nematodes, by TIE assay. The study here provides a new method for evaluating environmental risk and identifying toxicant(s) from the industrial e uent using C. elegans.     

我国防灾减灾领域学科发展及其专业设置——从学位管理制度谈起

我国高校在防灾减灾类人才培养中存在一些现实困境,如:灾害学的学科地位较低、防灾减灾类学科及专业设置不灵活、学校管理制度及其相关条例的约束等。从我国学位管理制度谈起,通过比较分析国内外高校专业设置与交叉学科发展情况,探讨我国防灾减灾领域学科发展及专业设置对防灾减灾人才培养造成的影响,并提出三点建议:一是加大我国学位管理制度的改革,确保落实高校办学自主权;二是对灾害科学的研究走向系统化、社会化,发展国内高等学校防灾减灾类专业本科教育;三是防灾减灾类专业课程设置从横向和纵向上都要体现综合和交叉的学科属性。     

Integrated control of the root-knot nematode, Meloidogyne incognita, on black-pepper plantations in the amazonian region

In the Amazonian region, so-called foot-rot disease, caused by a fungus Nectria, occurs widely on black-peppers, Piper nigrum L., the roots of which are also heavily infested by the root-knot nematode, Meloidogyne incognita. Factorial experiments were conducted in this region during 1976–1978 to attempt to find out the effect of nematicide treatment, mulching with Imperata cylindrica, and non-host cover plantings, on the growth of black-peppers as well as on nematode population levels. Temic or Furadan treatment resulted in better plant growth and a reduced nematode population in the first year. Mulching resulted in exceedingly high plant growth, even though higher nematode populations were also observed. Under mulching conditions, soil temperatures at 5-cm depth seldom rose beyond 30°C throughout the year. Cover plantings of non-hosts, which had been selected by earlier inoculation tests, indicated remarkable retardation of plant growth of black-peppers, evidently due to the competition, and this also reduced the nematode population. Macroptilium atropurpureum (siratro) gave the smallest growth retardation of black-peppers. From these results, a combination of three procedures, i.e. Temic or Furadan treatment, mulching with grass straw, and cover-planting of non-hosts such as siratro, is recommended on black-pepper plantations for better plant growth and eventually better yield of black-peppers in the fields infested by root-knot nematodes.     

辽河口海域浮游动物多样性及对河口环境的指示

于2013年8月（夏）、10月（秋）和2014年5月（春）在辽河口海域开展浮游动物多样性监测,研究了浮游动物种类组成和数量分布的时空变化特征,探讨了浮游动物多样性与河口盐度变化、富营养化等的关系。结果表明:辽河口海域浮游动物种类的季节更替明显,从夏季到秋季更替率为40.91%;从秋季到春季更替率为35.29%;夏季第一优势种为小拟哲水蚤（Paracalanus parvus）,春、秋季为双毛纺锤水蚤（Acartia bifilosa）。夏季浮游动物种（类）数明显高于春、秋季,由夏季阶段性浮游动物类群数增加所致,而桡足类的种类数季节间差异很小。春季浮游动物数量显著高于夏、秋季,其数量高达（6.4±1.3）×104 ind./m3,秋季数量最低为（5.5±0.6）×103 ind./m3。夏季多样性指数和均匀度指数高于春、秋季。浮游动物多样性的平面分布与盐度呈显著正相关,与无机氮和磷酸盐浓度显著负相关。河口指示性种类火腿伪镖水蚤（Pseudodiaptomus poplesia）的数量的平面分布与盐度呈显著负相关,与无机氮、磷酸盐浓度显著正相关。本研究能够为我国河口海域的生态监测和管理等提供参考依据。     

Characterization of dissolved organic matter fractions and its relationship with the disinfection by-product formation

Dissolved organic matter(DOM) has been identified as precursor for disinfection by-products(DBPs) formation during chlorination. Recently,it has been demonstrated that the characteristics of DOM influence the DBPs formation mechanism. A study was,therefore,initiated to investigate the effects of DOM fractions on DBPs formation mechanism. In the chlorination process,organic acids are dominant precursors of total thihalomethanes(TTHM) because of the νC-O and unsaturated structures. Furthermore,the TTHM format...     

泥沙腐殖质荧光特性及其与双酚A和类固醇吸附的关系

用批处理的方法测定了泥沙碱性可提取腐殖质对双酚A(BPA)和两种典型类固醇(17β-雌二醇(E2)和17α-乙炔基雌二醇(EE2))的吸附规律,分析了泥沙碱性可提取腐殖质的荧光光谱特征;探讨了腐殖质荧光光谱特征与BPA、E2和EE2吸附的关系.结果表明,泥沙碱性可提取腐殖质占泥沙总有机碳含量的9.3%～27.1%,BPA、E2和EE2三种物质的标化分配系数logKoc(hs)值变化范围分别为:3.14～4.09、3.47～4.33和3.65～4.32,其平均值大小顺序为EE2＞E2＞BPA,与3种物质辛醇水分配系数大小顺序一致.不同泥沙碱性可提取腐殖质的荧光光谱都有2个特征峰,其位置分别在Ex/Em=(310～330nm)/(390～400 nm)(α)和Ex/Em=(250～260nm)/(400～450nm)(α');2个特征峰峰强度比值(Iα'/Iα)变化范围为0.46～1.64;而且,泥沙中富里酸的荧光光谱与碱性可提取腐殖质的类似.腐殖质荧光光谱特征峰α由相对稳定、高分子量的芳香性类富里酸物质产生,随着芳香性类富里酸物质含量的增加Iα'/Iα值减小,因此,BPA、E2和EE2三种物质的logKoc(hs)与Iα'/Iα值间存在线性关系.     

三北防护林工程区植被覆盖变化与影响因子分析

利用1982~2006年间GIMMS AVHRR NDVI植被覆盖数据和气象站点气候数据,分析了三北防护林工程区25a来植被覆盖的时空变化特征及其与气温、降水变化的相关性,并在此基础上通过采用残差分析法探讨了人类活动对研究区植被覆盖变化影响的空间格局.结果表明:研究区25a的年植被变化量增加幅度略大于减少幅度,植被覆盖整体呈缓慢上升趋势,其中Ⅰ区和Ⅳ区NDVI值上升最明显(P<0.001),Ⅱ区则呈微弱下降趋势,而四大建设区植被覆盖度有不同程度提高;研究区植被和气温、降水整体呈正相关关系,17.74%的地区植被与气温呈负相关,而6.84%的地区呈正相关,10.60%的地区植被与降水呈负相关,19.53%的地区则呈正相关,植被与降水正相关面积明显大于植被与气温正相关面积,说明降水是研究区植被生长的关键因子;研究区植被残差年际变化显著正相关面积大于显著负相关面积,人类活动对植被建设作用要强于破坏作用,三北防护林建设工程带来的生态效益正在呈现.     

表面活性剂修饰氧化铋形貌及其超声降解性能研究

本实验分别用阴离子表面活性剂十二烷基硫酸钠(SDS)和十二烷基苯磺酸钠(SDBS)、阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)以及两种表面活性剂耦合进行修饰氧化铋形貌,并对修饰后的样品进行XRD、EDS、XPS、SEM等表征分析;同时探讨了表面活性剂修饰后的氧化铋在超声作用下对直接大红的最佳投加量和降解性能.结果表明:催化剂的最佳投加量为75 mg,最佳降解性能的样品为阴阳离子表面活性剂耦合修饰的氧化铋;当催化剂投加量为75 mg、初始浓度为10 mg·L-1、超声频率为45 k Hz、功率为100 W时,表面活性剂SDBS与CTAB在比例为1∶1耦合时修饰的氧化铋在20 min内对直接大红的总去除率达到99.4%,比空白实验提高16倍多.     

东苕溪蓝藻时空分布及其与环境因子关系研究

研究了东苕溪(太湖主要入湖河流)秋季和春季浮游植物的空间分布格局,监测了东苕溪18个采样点的浮游植物叶绿素a含量、细胞密度及种类组成等指标,分析了影响蓝藻时空分布差异的环境因子.结果表明:调查期间,共观察到浮游植物8门60属132种,其中,蓝藻门9属14种,蓝藻细胞密度占浮游植物细胞密度的平均比例为60.3%,蓝藻细胞密度自东苕溪下游至上游呈减小趋势,最高值出现在东苕溪下游距南太湖湖口3km以内.在秋季,东苕溪下游以铜绿微囊藻(Microcystis aeruginosa)为优势种,春季为水华鱼腥藻(Anabaena flos-aquae);丝状蓝藻(小席藻)是上游的优势代表种.东苕溪下游蓝藻的绝对优势与特殊的水动力条件、高浓度的营养盐有关.相关性分析表明,蓝藻细胞密度与水深(p<0.01)、总氮(p<0.01)和溶解性总碳(p<0.05)呈显著正相关.     

万山群岛海域网采浮游植物与环境因子的关系

根据2014年5月万山群岛海域生态环境调查数据,利用聚类分析和冗余分析等方法分析了网采浮游植物群落分布特征,探讨了珠江口盐度锋面生境对浮游植物群落的影响。结果表明:共发现网采浮游植物93种,硅藻门种类占73.1%。在冲淡水和外海水汇聚形成盐度锋面的混合区,水温、化学耗氧量、溶解氧、pH、叶绿素a和N:P均高,网采浮游植物丰度也最高,平均丰度为5.96×108/m3,数值达到其他两个区域平均丰度的4000倍以上,小个体硅藻中肋骨条藻丰度比例大于90.2%。在低盐区硅藻门丰度仍占80.6%,大个体硅藻门种类如锤状中鼓藻、巨圆筛藻、哈德半盘藻和美丽漂流藻等丰度呈上升趋势。在高盐区甲藻门丰度增至40.7%,形成硅藻门和甲藻门丰度联合占优势的群落结构,大个体甲藻门种类如短角角藻、纺锤角藻、大角角藻和夜光藻等丰度呈上升趋势。由于盐度变化大,网采浮游植物种类多样,且以广盐种种类和丰度占优势。万山群岛海域的水体营养特征使小型硅藻中肋骨条藻优势特别突出,而种类多样并且单一种类占主导优势的网采浮游植物群落特征,支撑了海域的高初级生产力。     

良渚聚落时空分布特征及其与环境变化的关系

良渚聚落是长江下游早期人类活动最重要的场所之一,是中华文明的重要源头。目前已广泛运用考古手段探索良渚聚落的人地关系,但大尺度分析聚落整体分布特征还相对薄弱。基于良渚聚落的相关资料,运用GIS空间分析技术,对聚落数据进行核密度、标准差椭圆、泰森多边形分析,揭示良渚聚落空间演变特征。结果表明：（1）良渚聚落一到四期总体呈现“南密北疏”的分布格局;由核密度可知其由多模式变为单核心模式;由标准差椭圆可知良渚聚落重心逐步向北迁移,同时椭圆形状在第四期发生重大变化;由泰森多边形可知聚落规模呈现一、二期最高等级领地数量相同,南北齐头并进发展,三、四期北部最高等级领地比南部多,出现群星环绕的局面。（2）良渚聚落的减少或增加与气候密切相关,同时气候变化带来的自然灾害如洪涝等进一步影响聚落的发展,而自然灾害的进一步加剧,有可能导致聚落群间的战争等一系列社会经济变化,最终导致良渚聚落逐渐衰落直至灭亡。