中国西南区扁穗牛鞭草种质遗传多样性的SRAP分析

本研究采用SRAP标记对主要来自中国西南地区(四川,重庆,贵州和云南)的43份扁穗牛鞭草种质资源的遗传多样性进行了分析。试验筛选出了11对引物组合对43份供试材料进行扩增,共获得153条带,其中多态性条带140条,多态性条带比率为91.50%,平均每对引物扩增出条带13.91,多态性条带12.73。实验数据结果表明,43份扁穗牛鞭草材料间的遗传相似系数(GS)为0.565～0.992,平均值为0.723,表现出了丰富的遗传多样性。聚类分析结果表明,各供试材料间的聚类与其地理来源以及形态特征类型具有一定的相关性。同时,主成分分析结果能够直观的反映了各种质间的遗传关系。5个扁穗牛鞭草地理类群间的分子方差分析(AMOVA)揭示了供试的扁穗牛鞭草总遗传变异的85.99%存在于类群内,仅有14.01%的变异存在于类群之间,类群间的分化系数ΦST=0.140。本研究结果为扁穗牛鞭草种质的收集、利用及育种提供了理论依据。     

应用植被措施控制非燃煤颗粒物的潜在效应

燃煤,当地扬尘,外地扬尘和机动车辆构成西安城市总悬浮颗粒物的80%,本研究回顾了在陕西控制非燃煤颗粒物源头已采取的包括绿色生态工程等措施;评价了发生在其他地区的绿色生态工程等其它措施;评价了应用植被和其它措施在其他地区的效应,由于悬浮颗粒物常常涉及到很大的范围而不是很小的范围,当我们讨论在西安的控制措施时,我们应该涉及到较大的范围,像陕西或其它地区,这样的话,我们就有可能把来龙去脉搞清楚,并使措施更得力一些;我们可用其它地区重要或经典的经历,经验作为重要或必要的参考,避免岐路,找到达到目标的捷径。     

科尔沁沙地灌丛的“虫岛”效应及其形成机理

为了了解沙地灌丛对于土壤动物是否存在聚集作用,于2008-2009年在科尔沁沙地调查了流动沙地小叶锦鸡儿和黄柳灌丛内外大型土壤动物的群落特征.结果表明:流动沙地灌丛内大型土壤动物类群数量、密度和Shannon多样性指数较灌丛外流沙地分别高125.0％ ～ 175.0％、52.8％ ～263.9％和34.6％ ～57.1％,显现出明显的“虫岛”效应,其中小叶锦鸡儿灌丛的“虫岛”效应大于黄柳灌丛;灌丛内外土壤优势动物类群虽然相同,并有少量共有类群,但灌丛下聚集了多个流沙裸地没有的大型土壤动物类群,群落功能群结构也发生明显改变;流动沙地灌丛的“虫岛”效应主要源于灌丛的小气候效应和肥岛效应,其降风滞尘、遮蔽暴晒、改善土壤质地和养分条件的作用是导致流动沙地灌丛“虫岛”效应形成的主要机理.     

鸟类的“帮手效应”

众所周知,繁殖鸟能否成功繁殖,并使后代存活取决于许多因素.繁殖鸟往往需要消耗很多的精力来进行繁殖,这对它们来说十分不利.但在部分鸟类中,存在一种常见的生殖合作形式,就是非双亲个体帮助繁殖鸟来喂养它们的后代.帮手鸟帮助它们筑巢,孵卵,觅食,喂食和保护领域等,极大提高了繁殖鸟的适合度,即所谓的"帮手效应".同时帮手鸟也获得了未来的适合度.     

人类群体遗传空间结构对应分析中的“蹄型效应”及其遗传学解释

探讨了人类群体遗传结构对应分析中“蹄型效应”的产生机制及其遗传学解释。从分析基因频率矩阵的结构特点入手,以实例验证和比较了对应分析中散点图的结构特征。发现当基因频率矩阵的结构不同时,其对应分析中散点图的分布模式不同;当基因频率矩阵中存在稀有基因时,其对应分析的散点图则呈现明显的“蹄型效应”。“蹄型效应”经常会歪曲潜在遗传结构的真实形态,其产生主要是因为对应分析中的c2距离不相似测度高估了稀有基因的作用。在人类群体遗传结构对应分析中,当出现“蹄型效应”效应时,需认真分析基因频率矩阵的结构,寻找“蹄型效应”产生原因并给出合理的遗传学解释,以免做出错误结论。     

激光诱变的生物学效应及其在动植物遗传育种上的应用

激光诱变是一种新型的育种技术,具有能量密度高,比较集中,单色性和方向性好,诱变当代即可出现遗传突变等特点。本文概述了激光诱变的一般原理和生物学效应,激光诱变后对植物形态,生理和遗传性状及动物早期胚肥发育的影响,旨在为深入研究激光诱变机制及其在动植物遗传育种上的应用提供参考。     

互花米草的两面性及其生态控制

互花米草是美国大西洋沿岸的本土植物,其高生产力、高繁殖率、高抗性和致密发达的地下部分等生物学特性使它能在沿海地区的抗风防浪、保滩护岸、促淤造陆、修复湿地和固定二氧化碳等方面发挥很好的正生态效应;然而,正是这与生俱来的生物学优势使该物种在引种地区侵占光滩,很快形成茂盛的单种优势群落,体现出很强的入侵性,从而也具有相当大的负生态效应。本文综述了互花米草的正负生态效应,分别从以下4个方面展开:抗风防浪的功效与改变景观的负作用,促淤造陆的功效与改变河口水文格局的负作用,固碳效应与释放温室气体的负作用,为一些物种提供营养与栖息地的同时对其他物种栖息环境的破坏性。研究证实,互花米草的本土化倾向已比较突出,如在超过100年引种历史的美国西部维拉帕湾、引种历史近40年的旧金山湾,以及引种历史近30年的我国大丰滩涂等。对于互花米草的生态控制,应结合各地的自然、社会、经济状况,因地制宜,如在一些生态脆弱(开发过度、缺乏大型植被、蚀退现象严重)的沿海地区,防灾减灾任务艰巨,根除互花米草须谨慎;在充分利用互花米草抗风防浪和促淤造陆后,可以适时围垦,以达到某些区域大面积减除的目标;此外,综合治理与利用相结合是较为科学的举措,既充分利用互花米草生物质(加工生产新食品、保健品、生物气等),又有效控制其种子飘落和扩繁,是一项生态工程,也是一种具有生态经济效益的利国利民之举。     

底栖有孔虫壳体微量元素地球化学指标及其“生命效应”

底栖有孔虫壳体的微量元素含量在海洋地球化学研究中有重要意义,Mg/Ca、Sr/Ca、B/Ca、Cd/Ca等是反演古海洋环境要素的有效指标。但是,有孔虫属种间、个体间甚至个体内部的壳体微量元素受到"生命效应"的影响,呈现出显著的差异。不同的样品处理方法、测试手段等因素,也会影响元素含量的测试结果。这些差异是有孔虫生物地球化学研究中的关键性问题,严重制约着元素指标的校准和应用。本文总结了近几十年来底栖有孔虫壳体主要微量元素指标的研究进展,首次系统地归纳了不同类群的微量元素含量差异,并结合有孔虫个体间以及个体内的差异信息,理清了元素指标的主要功能和关键问题,概述和分析了"生命效应"对元素指标的影响。     

肿瘤自杀基因治疗中的“旁观者效应”

肿瘤自杀基因治疗中的“旁观者效应”伍志坚（第一军医大学生物化学教研室,广州５１０５１５）关键词旁观者效应自杀基因基因治疗在肿瘤的基因治疗研究中,将“自杀基因（ｓｕｉｃｉｄｅｇｅｎｅ）”导入肿瘤细胞以激活自杀机制的策略占有重要地位。这类自杀基因包括单纯...     

基于供应链管理的CIO与CKO比较分析

通过对信息总监(chief information officer,CIO)和知识总监(chief knowledge officer, CKO)的职责比较务析,结合供应链管理(supply chain management,SCM)的需求与特点,分析在知识经济的背景下CIO和CKO在供应链管理中的作用。     

An Evaluation Model of Supply Chain Performances Using 5DBSC and LMBP Neural Network Algorithm

A high efficient Supply Chain (SC) would bring great benefits to an enterprise such as integrated resources, reduced logistics costs, improved logistics efficiency and high quality of overall level of services. So it is important to research various methods, performance indicator systems and technology for evaluating, monitoring, predicting and optimizing the performance of a SC. In this paper, the existing performance indicator systems and methods are discussed and evaluated. Various nature-inspired algorithms are reviewed and their applications for SC Performance Evaluation (PE) are discussed. Then, a model is proposed and developed using 5 Dimensional Balanced Scorecard (5DBSC) and LMBP (Levenberg-Marquardt Back Propagation) neural network for SC PE. A program is written using Matlab tool box to implement the model based on the practical values of the 14 indicators of 5DBSC of a given previous period. This model can be used to evaluate, predict and optimize the performance of a SC. The analysis results of a case study of a company show that the proposed model is valid, reliable and effective. The convergence speed is faster than that in the previous work.     

Contaminated food and uptake of heavy metals by fish: a review and a proposal for further research

Summary 1. The uptake of heavy metals via the alimentary tract can be an important factor for the metal budget of fish. 2. Concepts such as biomagnification, bioaccumulation, biotransference, or concentration factors, convey little information about the real threat originating from heavy metals in an aquatic food chain. 3. In polluted aquatic ecosystems the transfer of metals through food chains can be high enough to bring about harmful concentrations in the tissues of fish. This relationship is called the food chain effect. 4. Two kinds of ecological factors influence the food chain effect: firstly, high levels of contamination of the food, and, secondly, the reduction of species diversity. When susceptible species are eliminated, metal-tolerant food organisms may become dominant. Their tolerance may be based either on their ability to accumulate excessive amounts of metals or to exclude heavy metals from the tissues. These two strategies represent feedback mechanisms which may enhance or weaken the food chain effect. 5. It is concluded that future investigations on transference of heavy metals to fish must take into more careful consideration the specific ecological situation of a given environment.     

Effects of experimental duration and density of Japanese dace <Emphasis Type="Italic">Tribolodon hakonensis</Emphasis> on the strength of trophic cascades on benthic algae

To analyze density-mediated indirect effects through trophic cascades caused by Japanese dace Tribolodon hakonensis on the algal biomass and growth of ayu Plecoglossus altivelis altivelis, (freshwater fish belonging to Salmoniformes), I introduced zero, five, ten, and 20 dace with and without ayu into experimental pools. Ayu fed predominantly on benthic algae, whereas dace fed on both invertebrates and algae. The percentage of algae in the food content of dace was correlated with the number of dace in a pool. In the experiment lasting 8 days, trophic cascades on algae were not clear. In contrast, when the experimental duration was extended to 20 days, the number of gastropods and ephemeropteran nymphs was negatively correlated with the number of dace, consequently increasing the algal biomass and ayu growth through trophic cascades. Compared with pools with five dace, the presence of ten and 20 dace had similar gross effects on the number of algivorous invertebrates and algal biomass and greater gross effects on the ayu growth. The significant increase in ayu growth in pools with ten and 20 dace strongly suggests that small positive effects on algal growth by dace accumulated and extended to ayu during a 20-day experimental period. These results indicate the importance of analyzing interactions between the density and behavior of the top predator and the experimental duration on the intensity of trophic cascades.     

Top predator persistence in differential equation models of food chains: The effects of omnivory and external forcing of lower trophic levels

Persistence criteria are given for the highest trophic level predator in ordinary differential equation models of food chains exhibiting arbitrary omnivory and external supplementation of food source or an intermediate predator. The results are expressed in terms of inequalities involving the bounds on the intrinsic growth and interaction rates. Whether omnivory or external forcing enhances persistence is discussed, particularly for the examples of three-, four-, and five-link Lotka-Volterra food chains.     

Effect of Electroconvulsive Shock on Mitochondrial Respiratory Chain in Rat Brain

It is well described that impairment of energy production has been implicated in the pathogenesis of a number of diseases. Although several advances have occurred over the past 20 years concerning the use and administration of electroconvulsive therapy (ECT) to minimize its side effects, little progress has been made in understanding its mechanism of action. In this work, our aim was to measure the activities of mitochondrial respiratory chain complexes II and IV and succinate dehydrogenase from rat brain after acute and chronic electroconvulsive shock (ECS). Our results showed that mitochondrial respiratory chain enzymes activities were increased after acute ECS in hippocampus, striatum and cortex of rats. Besides, we also demonstrated that complex II activity was increased after chronic ECS in cortex, while hippocampus and striatum were not affected. Succinate dehydrogenase, however, was inhibited after chronic ECS in striatum, activated in cortex and not affected in hippocampus. Finally, complex IV was not affected by chronic ECS in hippocampus, striatum and cortex. Our findings demonstrated that brain metabolism is altered by ECS.     

Effects of nutrient recycling by zooplankton and fish on phytoplankton communities

In laboratory experiments we tested the hypothesis that nutrients supplied by fish and zooplankton affect the structure and dynamics of phytoplankton communities. As expected from their body size differences, fish released nutrients at lower mass-specific rates than Daphnia. On average, these consumers released nutrients at similar N:P ratios, although the ratios released by Daphnia were more variable than those released by fish. Nutrient supply by both fish and Daphnia reduced species richness and diversity of phytoplankton communities and increased algal biomass and dominance. However, nutrient recycling by fish supported a more diverse phytoplankton community than nutrient recycling by Daphnia. We conclude that nutrient recycling by zooplankton and fish have different effects on phytoplankton community structure due to differences in the quality of nutrients released. Received: 21 December 1998 / Accepted: 31 May 1999     

抗HBcAg人源性单链抗体细胞内表达及其抗病毒复制的实验研究

应用人源性抗HBcAg单链抗体细胞内表达技术,探讨抗HBV复制基因治疗的应用价值.应用噬菌体展示和基因重组技术,从HBV感染的外周血淋巴细胞克隆了人源性抗HBcAg单链抗体,并重组至逆转录病毒载体.以人肝癌细胞smmc-7721和PLC/PRF/5为靶细胞进行基因共转染,分别测定实验组细胞上清中的HBsAg和HBeAg,与对照组做比较,观察抗HBcAg单链抗体细胞内表达的抗病毒治疗作用.结果显示,在急性HBV感染的细胞株中,抑制病毒复制效率为49%～61%,在慢性病毒感染细胞,抑制率为41%～54%.实验结果表明,应用单链抗体细胞内表达技术,在抗病毒治疗研究中具有潜在的应用价值.应对HBV的4个开放阅读框架编码产物进行全面的对比研究,以发现抑制效率高、实用价值大的靶基因.     

Effect of Peroxynitrite on the Mitochondrial Respiratory Chain: Differential Susceptibility of Neurones and Astrocytes in Primary Culture

Abstract: The effect of the neurotoxic nitric oxide derivative, the peroxynitrite anion (ONOO⁻), on the activity of the mitochondrial respiratory chain complexes in cultured neurones and astrocytes was studied. A single exposure of the neurones to ONOO⁻ (initial concentrations of 0.01–2.0 m M ) caused, after a subsequent 24-h incubation, a dose-dependent decrease in succinate-cytochrome c reductase (60% at 0.5 m M ) and in cytochrome c oxidase (52% at 0.5 m M ) activities. NADH-ubiquinone-1 reductase was unaffected. In astrocytes, the activity of the mitochondrial complexes was not affected up to 2 m M ONOO⁻. Citrate synthase was unaffected in both cell types under all conditions studied. However, lactate dehydrogenase activity released to the culture medium was increased by ONOO⁻ in a dose-dependent manner (40% at 0.5 m M ONOO⁻) from the neurones but not from the astrocytes. Neuronal glutathione concentration decreased by 39% at 0.1 m M ONOO⁻, but astrocytic glutathione was not affected up to 2 m M ONOO⁻. In isolated brain mitochondria, only succinate-cytochrome c reductase activity was affected (22% decrease at 1 m M ONOO⁻). We conclude that the acute exposure of ONOO⁻ selectively damages neurones, whereas astrocytes remain unaffected. Intracellular glutathione appears to be an important factor for ameliorating ONOO⁻-mediated mitochondrial damage. This study supports the hypothesis that the neurotoxicity of nitric oxide is mediated through mitochondrial dysfunction.     

猪T细胞受体γ链基因的克隆及生物信息学分析

目的:克隆猪T细胞受体γ链(pTCR-γ)基因,用以研究猪T细胞受体分子结构与功能。方法与结果:以GenBank上登载的pTCR-γ基因为参考序列,用RT-PCR法从猪外周血淋巴细胞中克隆pTCR-γ基因。序列分析表明,pTCR-γ基因开放读框为1026bp,编码341个氨基酸残基,含有由23个氨基酸残基构成的信号肽序列;与参考序列相比,在核苷酸和推导氨基酸序列上的同源性分别为95.6%和88.8%;系统进化分析发现,该基因与绵羊、恒河猴、人、马、牛的同源性相对较高,与褐鼠、家犬、家鼠、家猫的同源性次之,而与禽类、鱼类的同源性最低;生物信息学结构预测表明猪T细胞受体γ链含2个结构域,其中1个为IG_LIKE1结构域(IGv结构域),由第14～114位共101个氨基酸残基组成;另一个为IG_LIKE2结构域(IGc结构域),由第143～238位共96个氨基酸残基组成。结论:克隆并应用生物信息学技术分析了猪T细胞受体γ链基因序列及编码蛋白的结构特征,为进一步研究γ链的结构与功能奠定了基础。