丹江口水库浮游植物时空动态及影响因素

2007年7月至2008年6月对丹江口水库浮游植物进行了为期一年的调查和分析,共采集到浮游植物8门、60属、110种及变种.种类组成以绿藻门、硅藻门和蓝藻门为主,其中绿藻门占优势,共计46种(42％),其次为硅藻35种(32％).藻类年平均密度为4.17×106 celVL,最高密度为6.10×107 cell/L,最低密度为5.16×103 cell/L.各季节浮游植物优势种差异显著,春季为一种颤藻(Oscillatoria sp.)和尖针杆藻(Synedra acus),夏秋两季为啮蚀隐藻(Cryptomonas erosa),冬季转为倪氏拟多甲藻(Peridiniopsis niei).空间分布上,丹江、汉江库区以及取水口3个区域浮游植物优势种为尖针杆藻,五青入库区则以倪氏拟多甲藻占优势.磷浓度是驱动丹江口水库藻类密度的主要影响因子.根据建库几十年来的对丹江口水库较为全面的4次调查资料,分析了丹江口水库的浮游植物群落演替及变化趋势.自1958年以来,50年间,整个水库浮游植物密度增加了16倍,水库富营养化程度有增加的趋势.种类组成由适应河流的固着型硅藻,经过硅藻-绿藻-蓝藻型逐渐发展为硅藻-甲藻-隐藻-蓝藻型.     

朱砂叶螨对不同农药抗药性发展趋势的研究

探讨朱砂叶螨室内种群的抗药性发展状况。实验结果表明,氧化乐果、三氯杀螨醇、双甲脒、哒螨灵对于朱砂叶螨种群,只要给予一定的选择压力,经数次用药该螨就会发展对这些杀虫(螨)剂的抗性,且随着用药次数的增加,各品系抗药性呈现上升趋势。在相同条件下,该螨对上述药剂的抗性发展速率不同,4种杀虫(螨)剂抗性发展速率由大到小依次为:氧化乐果、双甲脒、三氯杀螨醇、哒螨灵。     

基于知识图谱的植物功能性状与环境研究前沿态势分析

为系统了解国际上植物功能性状与环境的研究进展,该研究基于Web of Science数据来源,采用Web of Science数据库分析工具和Thomson Data Analysis(TDA)进行数据清理和统计分析,并利用Ucinet和Netdraw、Excel等软件进行可视化作图。结果表明:(1)近26年来,植物功能性状与环境研究论文数量呈持续稳步增长态势,尤其近9年来呈加速增长态势。(2)近9年来,研究主题主要围绕比叶面积、叶面积(指数)、光合作用(性能)、叶厚度、叶形态、叶氮含量、叶绿素、叶绿素荧光、比根长等功能指标,及光照、温度、水(水分利用效率、干旱等)、肥(氮、磷为主)、CO2等环境因子展开;化学计量学在该领域应用广泛。(3)2009—2017年间,欧美等发达国家是该领域研究的主要力量。美国发文数量和文献质量均为世界领先。中国在该领域的发文量居第二位,仅次于美国,但文献篇均被引和H指数较低。中国科学院发文量以绝对优势居第一位,但文献质量有待进一步提升。(4)该领域载文量Top10期刊8种为JCR分区Q1区、2种为Q2区。其中,Plant and Soil和Plant Ecology载文量分居第一位和第二位。(5) Top10高被引论文发表于8种期刊,其第一作者分别来自美国、荷兰、加拿大、德国和法国。     

Refuge use in sticklebacks as a function of body length and group size

A change in anti–predator strategy from hiding to grouping outside a refuge was observed in large three–spined sticklebacks. No such change in strategy was seen in small fish. The body–length dependence of this strategy change is discussed in the context of metabolic constraints.     

The relationship between foraging and shoal position in a mixed shoal of roach (Rutilus rutilus) and chub (Leuciscus cephalus): a field study

Feeding rates of mixed shoals of juvenile roach and chub were observed in a shallow stream near Cambridge (UK). Roach at the front of the shoal had significantly higher feeding rates than roach at the back and than chub in either front or back positions. Position in the shoal also had a significant effect on the kind of food consumed, with front roach feeding more on plankton and back roach more on bottom food. Altogether 36 fish from the stream were caught and marked. Half of these were deprived of food and the other half well-fed for 3 days in captivity. After release 36% of them joined their old shoal again. Individuals from the starved group occupied front positions significantly more often than well-fed fish, but after 2 days this difference disappeared.     

低出血倾向、低免疫原性葡激酶mSAK(K130T,K135R)的表达、纯化与活性测定

为了有效降低葡激酶应用的副作用,构建低出血倾向、低免疫原性葡激酶突变体,高效表达纯化后进行活性鉴定,以野生型重组葡激酶基因为模板,PCR法引入突变位点(K130T,K135R),并将该片段克隆测序鉴定后,克隆至表达载体pBV220,构建低免疫原性葡激酶突变体.表达后的蛋白用Q-SepharoseFF柱与SephacrylS-200进行纯化,纤维蛋白溶圈法进行活性测定,体外抗体中和试验与豚鼠免疫试验测定突变体蛋白的免疫原性,同时进行动物体内出血倾向观察.测序结果表明,相应位点获得突变,无非特异性突变,将突变后的片段连接pBV220导入大肠杆菌热激诱导获得了高效表达,表达产物占菌体总蛋白的40%~50%.产物主要以可溶性形式存在,经两步纯化后的蛋白的纯度可达98%以上.活性测定试验表明,该突变体的活性较野生型葡激酶稍低,体外中和抗体试验和豚鼠免疫试验证明免疫原性大为下降,豚鼠的皮肤出血以及肺部病理切片均显示该突变体蛋白引起的出血倾向明显降低.     

Impaired plasma clottability induction through fibrinogen degradation by ASP, a serine protease released from Aeromonas sobria

Aeromonas sobria infection often advances to sepsis, in which interaction of bacterial components with plasma proteins possibly causes various disorders. This bacterium releases a serine protease (ASP), a putative virulence factor, and binds to fibrinogen. To study the ASP effect on fibrinogen, we incubated fibrinogen or plasma with ASP and investigated their clotting elicited by thrombin, which converts fibrinogen to a fibrin clot. Enzymatically active ASP retarded plasma clotting in a dose-dependent manner starting at an ASP concentration of 10 nM. ASP also retarded fibrinogen clotting at 3 nM and above, which appeared to correspond to ASP cleavage of fibrinogen at the A alpha-chain. Consistent with containing serine protease activity for an ASP-specific substrate, the culture supernatant of an ASP gene-introduced strain retarded plasma and fibrinogen clotting more than that of the wild-type strain. The culture supernatant of an ASP gene-disrupted strain that releases negligible serine protease activity for the ASP-specific substrate did not affect plasma clotting. These results indicate that ASP is the main fibrinogenolytic protease released from A. sobria. Impaired plasma clottability induction through fibrinogen degradation is a new virulence activity of ASP and may contribute to hemorrhagic tendencies in sepsis caused by infection with this bacterium.     

Background colouration influences body colour segregation in mollies

When given a choice of swimming against a black background near an empty black end compartment or swimming against a white background near an empty white compartment, black morph mollies Poecilia latipinna spent significantly more time against the black background. The presence of a shoal (either white or black mollies) in the black compartment increased the preference of the test fish for the black background. However, black molly test fish spent significantly less time against a black background if a black shoal was present in the white compartment than in assays in which a white shoal was in the white compartment. In assays where test fish were given the choice between two black shoals, test fish spent significantly more time near the black shoal on the black background. Similarly, when given the choice between two white shoals, test fish spent significantly more time against the black background. The results suggest that the presence of cryptic backgrounds alter shoalmate choices in fish that assort according to body colouration.     

Fish odour triggers conspecific attraction behaviour in an aquatic invertebrate

Group living has evolved as an adaptation to predation in many animal species. In a multitude of vertebrates, the tendency to aggregate varies with the risk of predation, but experimental evidence for this is less well known in invertebrates. Here, we examine the tendency to aggregate in the freshwater amphipod Gammarus pulex in the absence and presence of predator fish odour. Without fish odour, the gammarids showed no significant tendency to aggregate. In contrast to this, in fish-conditioned water, they significantly preferred to stay close to conspecifics. Predation risk can, thus, influence gammarids social behaviour.