苗期玉米根叶对干旱胁迫的生理响应

采用人工控制水分的方法,研究了干旱胁迫下苗期玉米(ZeamaysL.)根系和叶片的生理指标,用以明确苗期玉米根系和叶片对干旱的生理响应。研究结果表明,苗期中度干旱胁迫处理条件下,玉米根系和叶片均表现出对干旱胁迫的生理响应,并各具特点。与对照相比,干旱胁迫使玉米根系和地上部的生物量降低,叶片中的叶绿素含量显著降低、叶片光合面积减小,根冠比增大。干旱胁迫使玉米根系比表面积增大,根系氧化活力和还原活力增强。干旱胁迫导致玉米叶片的光合功能降低,初始荧光升高,初始光系统Ⅱ(PSⅡ)的原初光能转换效率、PSⅡ潜在活性、潜在光合作用活力均受到抑制。干旱胁迫下玉米叶片和根系脂质过氧化作用增强,根系和叶片中的游离脯氨酸含量升高。     

二氧化硫体内衍生物对小鼠的显性致死作用

采用二氧化硫(SO2)衍生物亚硫酸钠和亚硫酸氢钠(二者的物质的量之比为3:1)腹腔注射的方法,研究其对雄性小鼠生殖细胞的遗传毒性.结果表明,雄鼠经SO2衍生物染毒后再与雌鼠交配,导致:(1)雌鼠受孕率下降,显性致死率增高,且均有明确的剂量-效应关系;(2)胚胎生长迟缓,活胎平均重量下降.研究得出结论:SO2及其衍生物对雄性小鼠有生殖毒性作用.表2参14     

番茄某些繁殖特性对增强UV-B辐射的响应

研究了增强UV-B辐射对大田生长的两种番茄(早熟型“同辉”和晚熟型“霞光”)某些繁殖特性(最大开花数、花粉萌发和花粉管伸长、果实产量、果实品质以及子代种子的数量和质量)的影响.结果表明,与对照相比,“同辉”开花数在高辐射下增加,“霞光”开花数在低辐射下减少;“同辉”果实产量在两种辐射下都明显增加,而“霞光”果实产量只在低辐射下增加;辐射抑制了“同辉”的花粉萌发和花粉管伸长,而只是降低了“霞光”的花粉萌发率;强辐射造成两种番茄果实番茄红素下降。经过一季的增强UV-B辐射处理,“同辉”种子数量增加,低辐射下种子明显变小;“霞光”种子数量减少,且明显变小.就开花数、果实产量和种子质量而言,早熟的“同辉”品种更具抗性,而晚熟的“霞光”更敏感.图3表1参29     

几种植物源农药对环境生物的毒性

测定了几种植物源农药对几种环境生物的急性毒性.结果表明:不同植物源农药对同一种环境生物的毒性差异很大,同一种植物源农药对不同的环境生物毒性也不同;说明并非所有的植物源农药都是安全的.表4参5     

Chemical ornaments of male lizards <Emphasis Type="Italic">Psammodromus algirus</Emphasis> may reveal their parasite load and health state to females

Evidence for parasite-mediated sexual selection has been found in many species that use visual ornaments to attract females. However, in many animals, variation in female responses to scents of parasitized males suggests that parasitic infections might also affect information conveyed by pheromones (i.e., chemical ornaments). Thus, pheromones might also function in parasite-mediated sexual selection. We show here that female lizards Psammodromus algirus responded differently to femoral gland secretions of males according to the parasite load and health of these males. Scents of healthier males elicited more tongue flicks (a chemosensory behavior) by females, suggesting that these scents were more attractive. Chemical analyses showed that parasite load and the T-cell-mediated immune response were related to the variability in the proportions of some lipids in secretions of males. Further trials testing the chemosensory responses of females to chemical standards indicated that females actually discriminated the chemicals related to males’ health from other chemicals found in secretions. We suggest that these chemical ornaments may provide reliable information on the health and degree of parasitic infection of a male.     

蒽醌类化合物对大型蚤(Daphnia magna)的急性光致毒性研究

通过测定模拟光照和无光照条件下20种蒽醌类化合物对大型(Daphnia magna)的48h半数活动抑制浓度(EC50), 研究了该类化合物的光致毒性．比较了两种助溶剂(二甲基亚砜和丙酮)对这些化合物光致毒性的影响,初步讨论了光致毒性的机理．结果表明,所研究的助溶剂不影响这些化合物对大型潘的光致毒性．蒽醌类化合物因其取代基的不同(-NH2、-OH、-Cl、-Br、-NO2)、取代基位置的不同和取代基数目的不同,而表现出对大型潘光致毒性的不同．最低未占据分子轨道能(ELUMO)和最高占据分子轨道能(EHOMO)之间的能级差,可用于初步判断蒽醌类化合物 溞大型的潜在光致毒性．     

三种典型渔药对大型溞(Daphnia magna)的急性毒性及其关键环境影响因子分析

测试了三种典型渔药三氯异氰尿酸(Trichloroisocyanuricacid,TCCA)、叔丁基对羟基茴香醚(Butylatedhydroxyanisole,BHA)、盐酸环丙沙星(Ciprofloxacinhydrochloride,CPFX)对大型(Daphniamagna)的急性毒性。结果表明,对于大型的毒性由大到小的顺序为:三氯异氰尿酸,叔丁基对羟基茴香醚,盐酸环丙沙星,48hLC50分别为0.19mg·L-1,3.15mg·L-1和135.15mg·L-1。通过三因素三水平正交试验分析了主要环境因子pH值、硬度、腐殖酸对三种渔药对大型毒性的影响,发现pH显著影响TCCA的毒性,硬度显著影响CPFX的毒性,而BHA毒性受环境因素影响不显著。     

Causasilty among wildfire,ENSO, timber harvest,and urban sprawl: The vector autoregression approach

This article demonstrates the applicability of vector autoregression (VAR) modeling in probing the causality relationships among wildfire, El Niño/Southern Oscillation (ENSO), timber harvest, and urban sprawl in the U.S. The VAR approach allows for the multi-directional, multi-faceted interactions among the variables concerned and enables us to portray the temporal impacts of ENSO, the volume of timber harvested, and urban sprawl on wildfire. The empirical analysis, though intended mainly for illustration, reveals that an individual factor may not affect wildfire activity (number of fires and area burned) when acting alone, but can significantly influence fire activity when coupled with other factors, and that wildfire activity has feedback effects on other variables. The impact of a change in ENSO, the volume of timber harvested, and urban population density on wildfire activity could last two decades with the most noticeable impact occurring in the initial 5–10 years. Though ENSO, timber harvest, and urban sprawl all Granger-cause wildfire activity, the impulse response functions show that wildfire activity is more responsive to urban population density than to the volume of timber harvested or ENSO. Thus, controlling urban sprawl represents another option for wildfire mitigation; and integrative wildfire management is essential.     

Ladybird defence alkaloids: Structural,chemotaxonomic and biosynthetic aspects (Col.: Coccinellidae)

Summary The defensive mechanisms which protect ladybird beetles (Coccinellidae) against predators are reviewed. Besides behavioural mechanisms, such as thanatosis and reflex bleeding, chemical defence mechanisms are playing a prevalent role. Indeed, ladybirds are protected not only by their smell, but also by repulsive alkaloids, most of which are considered to be of autogenous origin. In a few cases, dietarily-acquired substances are also involved. Particular emphasis is laid on the repellent alkaloids which are contained in the haemolymph of many species. The structures of 34 nitrogen-containing compounds isolated so far are presented, and their distribution within the family is discussed in the light of the most widely accepted classification of these beetles. To conclude, the mode of release of the alkaloids, their variation through the life cycle and their repellent and toxic properties are discussed, as well as the few biosynthetic data yet available.     

陆地生物配体模型（t-BLM）初探：镁离子降低铜离子对小麦根的毒性

生物配体模型(BLM)同时考虑了水中金属离子的化学形态以及阳离子与金属离子在生物配体(BL)上的竞争对其毒性的影响,能成功预测水体金属的生物毒性/有效性.最近,BLM呈现出向土壤环境中拓展的趋势,发展能预测重金属对土壤生物毒性的陆地生物配体模型(t-BLM)正成为最新的国际研究热点.论文模拟土壤溶液,以土壤溶液中的主要阳离子Mg2+为例,通过单因素浓度控制-恒pH营养液培养-陆生植物根伸长抑制试验,定量探讨了不同浓度Mg2+存在下,铜离子(Cu2+)对小麦(Triticum aestivum)根的毒性.结果表明,Mg2+浓度升高显著减弱了Cu2+对小麦根的毒性,即呈现出保护效应.证实陆地生态系统中也存在阳离子对重金属植物毒性的保护效应,支持了BLM中阳离子和重金属离子在生物配体上存在竞争结合的假设,即BLM概念适用于陆生植物.定量分析表明,小麦根生长抑制的毒性效应指标EC50(以自由铜离子活度表示)与自由镁离子活度间存在良好的相关性,线性回归方程为:pEC50(Cu2+)=-0.36(Mg2+)+6.47(r2=0.9976),Mg2+对Cu2+毒性的影响强度可以通过该方程进行预测.论文积累了重金属铜对典型陆生受试植物小麦的毒性数据,探讨了t-BLM的构建方法学,并为其发展提供了思路.联合了土壤理化性质、金属形态及生物积累和毒性效应的t-BLM,将提供一个环境风险评价和制定土壤质量标准的新工具.