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。     

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     

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.     

底质中氨氮对沉水植物生长的影响

沉水植物的生长不但与水体营养盐浓度具有十分密切的关系,也受底泥中营养物质的影响,尤其是底泥中氨氮的含量对于植物生长具有重要的作用,因此研究底质中氨氮对高等沉水植物生长的影响,能够为沉水植被的重建及选种提供科学参考。作者在人工配制的7种含不同浓度铵态氮的底质条件下,通过测定苦草VallisnerianatansL.和伊乐藻Elodeanuttallii两种沉水植物的植株鲜物质量的变化、干物质量、根系的活力、过氧化物酶(POD)和过氧化氢酶(CAT)活性,以期明确这两种沉水植物与水体底质浓度之间的关系。试验结果表明,氨氮起始质量分数<50mg·kg-1和<500mg·kg-1时可以分别促进苦草和伊乐藻鲜物质量、干物质量和根系活力的增加,大于此范围则会抑制苦草VallisnerianatansL和伊乐藻Elodeanuttallii的生长。     

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.     

Differential responses of honeybee (<Emphasis Type="BoldItalic">Apis mellifera</Emphasis>) patrilines to changes in stimuli for the generalist tasks of nursing and foraging

Which task a social insect worker engages in is influenced by the worker’s age, genotype and the colony’s needs. In the honeybee, Apis mellifera, genotype influences both the age a worker switches tasks and its propensity of engaging in specialist tasks, such as water collecting, which only some workers will perform. In this study, we used colonies with natural levels of genetic diversity and manipulated colony age demography to drastically increase the stimuli for the generalist tasks of foraging and nursing, which all workers are thought to engage in at some point in their lives. We examined the representation of worker patrilines engaged in nursing and foraging before and after the perturbation. The representation of patrilines among foragers and nurses differed from that of their overall colony’s population. In the case of foraging, over- and underrepresentation of some patrilines was not simply due to differences in rates of development among patrilines. We show that replacement foragers tend to be drawn from patrilines that were overrepresented among foragers before the perturbation, suggesting that there is a genetic component to the tendency to engage in foraging. In contrast, the representation of patrilines in replacement nurses differed from that in the unperturbed nursing population. Our results show that there is a genetic influence on even the generalist tasks of foraging and nursing, and that the way patrilines in genetically diverse colonies respond to increases in task stimuli depends upon the task. The possible significance of this genetic influence on task allocation is discussed. Electronic supplementary material Supplementary material is available in the online version of this article at doi: and is accessible to authorized users.     

红豆杉细胞抗病反应的诱导及其与紫杉醇合成的关系

采用从红豆杉植株不同部位（叶、内皮、根等）分离筛选获得的各种真菌制备的激发子，对6种不同红豆杉细胞株进行诱导作用研究。结果表明，不同细胞对不同真菌制备的激发子的抗病反应有显著的区别，并建立3种-具菌互作模式：极不相容（细胞抗性强，受损小），不相容（抗性强，受损也较严重），相容（细胞抗性小，受损严重）。结果还表明，极不相容和不相容互作模式中细胞的紫杉醇产量显著高于CK，而相容互作模式的细胞不合有紫杉, 同一真菌由不同的方法制备成的不同分子量大小或不同成分的激发子，对细胞的抗病反应与紫杉醇合成的影响不同,这些结果为诱导作用机理及调控红豆杉细胞合成紫杉醇的研究具有指导意义。     

镉对稻田土壤典型微生物种的胁迫生理毒性

以水稻田土壤中典型的单种微生物为实验材料,采用纯培养方法,从个体水平上全面探讨了重金属镉胁迫对稻田土壤典型微生物的的生长、活性以及生化过程的生理毒性影响。研究表明:不同微生物纯培养对镉胁迫的敏感程度不同,G 较G-对Cd2 更为敏感,表现为世代时间缩短,最高菌浓度下降。固氮菌对Cd2 非常敏感,当Cd2 质量浓度为0.2mg·L-1时即完全抑制菌体增殖。同时,外源镉强烈的抑制作为稻田土壤中功能微生物的厌氧固氮菌及产甲烷细菌的生物活性,各菌种镉胁迫下细菌细胞内可溶性蛋白、还原糖、核酸质量浓度都在低质量浓度镉胁迫时有所增加;随着镉质量浓度的增加,细菌细胞内各种物质的质量浓度开始减小,以减慢细胞代谢速度,增强对镉胁迫的适应力;各种物质的质量浓度变化趋势为可溶性蛋白>还原糖>核酸,R.eutrophaDKC1细胞内含物质量浓度基本保持稳定。结果可在一定程度上说明镉对微生物的毒性效应,且能在早期较灵敏地指示污染的影响,作为稻田土壤环境受到污染胁迫的细胞生化指标具有一定可行性。     

Crop Failure in Dalocha, Ethiopia: A Participatory Emergency Response

This case study of an NGO's response to a food crisis due to crop failure focuses on the extent of active community participation at each stage of the project. With the current debate on the relationship between relief and development, and in particular the focus on encouraging more active community participation in relief responses, this study has relevance both in the Ethiopian context and beyond.
In this example the participation process was greatly facilitated by the prior relationship between the international NGO and the communities, and also by the high level of staff input into the project. Where resources or conditions are less favourable, as might be the case in similar responses by local NGOs or government agencies, the paper suggests that the participatory approach can be adapted or partially implemented and still result in a more effective and locally relevant operation.     

加速遗传算法及其在暴雨强度公式参数优化中的应用

提出了一般非线性自然灾害模型参数优化的一种通用的数值方法———加速遗传算法,分析了该算法控制参数的优化特性,总结出了这些参数的简便设置技术,并给出了它在暴雨强度公式参数优化中的应用实例。该方法可广泛应用于各种自然灾害模型的优化问题。