A genetic screen for vascular mutants in zebrafish reveals dynamic roles for Vegf/Plcg1 signaling during artery development

In this work we describe a forward genetic approach to identify mutations that affect blood vessel development in the zebrafish. By applying a haploid screening strategy in a transgenic background that allows direct visualization of blood vessels, it was possible to identify several classes of mutant vascular phenotypes. Subsequent characterization of mutant lines revealed that defects in Vascular endothelial growth factor (Vegf) signaling specifically affected artery development. Comparison of phenotypes associated with different mutations within a functional zebrafish Vegf receptor-2 ortholog (referred to as kdr-like, kdrl) revealed surprisingly varied effects on vascular development. In parallel, we identified an allelic series of mutations in phospholipase c gamma 1 (plcg1). Together with in vivo structure-function analysis, our results suggest a requirement for Plcg1 catalytic activity downstream of receptor tyrosine kinases. We further find that embryos lacking both maternal and zygotic plcg1 display more severe defects in artery differentiation but are otherwise similar to zygotic mutants. Finally, we demonstrate through mosaic analysis that plcg1 functions autonomously in endothelial cells. Together our genetic analyses suggest that Vegf/Plcg1 signaling acts at multiple time points and in different signaling contexts to mediate distinct aspects of artery development.     

Chromosomal location of a gene for resistance to septoria tritici blotch (Mycosphaerella graminicola)in the hexaploid wheat ’Synthetic 6x’

Septoria tritici blotch, caused by the fungus Mycosphaerella graminicola,is currently the major foliar disease of wheat world-wide, and new sources of resistance and knowledge about the genetics of resistance are needed to improve breeding for resistance to this disease. Sears’s ’Synthetic 6x’ hexaploid wheat, derived from a hybrid of Triticum dicoccoides and Triticum tauschii, was resistant to 12 of 13 isolates of M. graminicola tested. Chromosome 7D of ’Synthetic 6x’ was identified as carrying resistance to all 12 isolates in tests of seedlings of inter-varietal chromosome substitution lines of ’Synthetic 6x’ into ’Chinese Spring’ and to two isolates in tests of adult plants. A septoria tritici blotch resistance gene, named Stb5, was identified using the M. graminicola isolate IPO94269 and mapped on the short arm of chromosome 7D, near the centromere, in a population of single homozygous chromosome-recombinant lines for the 7D chromosome. Received: 1 February 2001 / Accepted: 17 April 2001     

Divergence in germination traits among arctic and alpine populations of <Emphasis Type="Italic">Koenigia islandica</Emphasis>: light requirements

Light is known to regulate conservative germination strategies and the formation of seed banks. Although these strategies are crucial to survival in tundra environments—especially for annuals—light requirements for germination in arctic–alpine species are seldom investigated. Furthermore, environmental differences between arctic and alpine regions are expected to lead to evolutionary divergence among conspecific populations in seed germination strategies. In this study, we report important differences in germination light requirements among six arctic and alpine populations of the annual Koenigia islandica. Light had little effect on germination of the seeds from Iqaluit (Nunavut, Canada), Yukon (Canada), and Jasper (Alberta, Canada), whereas the seeds from the most severe climates, Svalbard (Norway) and Colorado (USA), had strong light requirements. Stratification of the seeds had little influence on their germination light requirements, with the exception of the population from Dovre (Norway), in which it induced a strong light requirement. Possible adaptive explanations and some implications of these observed germination patterns are discussed.     

Prospects for manipulating the substrate specificity of ribulose bisphosphate carboxylase/oxygenase

Pierce, J. 1988. Prospects for manipulating the substrate specificity of ribulose bisphosphate carboxylase/oxygenase. - Physiol. Plant. 72: 690–698.
The idea of enhancing plant productivity by minimizing the apparently wasteful process of photorespiration has been an enduring one. Since the relative fluxes of carbon through the competing pathways of photosynthesis and photorespiration are determined by the kinetic properties of a single enzyme, ribulose bisphosphate carboxylase/oxygenase, it has been conjectured that genetic modification of this protein could provide more productive plants. Recent advances in techniques for studying ribulose bisphosphate carboxylase/oxygenase hold promise for determining whether such modifications will prove possible.     

森林生态系统健康与野生动植物资源的可持续利用

研究了森林生态系统健康与野生动植物资源之间的关系,以及人类活动对森林生态系统健康的影响,提出了以下三个论点：(1)野生动植物资源是构成森林生态系统的基本物质内容。野生动植物资源对森林生态系统具有不可估量的影响和作用。(2)野生动植物资源的减少是森林生态系统健康状况下降的“显示器”。森林生态系统健康状况的下降或衰退,会导致野生动植物资源数量或种类的减少甚至种群灭绝。(3)森林生态系统是野生动植物资源与人类活动关系的集合体和反映体。人类与野生动植物资源是对立又统一的矛盾综合体,而森林生态系统健康与否就取决于这二者的关系。如果人类对野生动植物资源在保护的基础上进行合理的利用,就能保证森林生态系统的结构的完整和功能的良好,因此森林生态系统处于健康的状态;但若人类对野生动植物资源过度利用而不加保护,那么随着野生动植物资源的逐渐衰竭,森林生态系统将逐渐失去某些功能且变得支离破碎,也就无法保持健康的状态。提出了维持森林生态系统健康并实现野生动植物资源可持续利用的解决途径：(1)实行森林的可持续经营。森林可持续经营是指长期保持森林的生产力和可再生性,以及森林生态系统的物种和生物多样性。(2)发展“接近自然的林业”。近自然林业是在服从自然规律的前提下为人类的木材及林产品利用目的而设计的容许有一点偏离自然的森林模式,以森林生态健康为目标的建设方法。     

五株纤毛虫遗传关系的ISSR分析

采用ISSR分子标记技术,尝试对四种五株纤毛虫(褶累枝虫(Epistylis plicatilis)、绿草履虫(Paramecium bursaria)、多态喇叭虫(Stentor polymorphus)、嗜热四膜虫BF1株(Tetrahymena thermophilaBF1)和嗜热四膜虫BF5株(T.ther-mophilaBF5))进行遗传关系研究。用13个ISSR引物对五株纤毛虫进行扩增,六个ISSR引物获得多态片段。根据Nei s遗传距离矩阵构建了五株纤毛虫的遗传关系树状图。UPGMA,NJ聚类图表明:两株嗜热四膜虫最先聚在一起;其次是褶累枝虫和多态喇叭虫聚在一起,然后再与嗜热四膜虫聚在一起;咽膜亚纲的绿草履虫形成独立的一枝。结果显示:①缘毛亚纲纤毛虫可能是寡膜纲中较独特的一个类群,建议提升缘毛亚纲纤毛虫的分类地位;②缘毛亚纲褶累枝虫与膜口亚纲嗜热四膜虫的亲缘关系近于咽膜亚纲绿草履虫,在寡膜纲中绿草履虫处于原始地位;③五株纤毛虫基因组中均含有微卫星DNA序列:(GTG)4(、GACA)4(、AG)8(、CAA)6和(GAA)6。     

福尔马林固定白暨豚标本DNA提取及其遗传多样性的初步研究

福尔马林固定标本是宝贵的遗传资源,但是如何有效利用其中的遗传信息一直存在问题。本文尝试从标本预处理、消化、PCR扩增各方面综合考虑和优化改进,成功提取并扩增21头福尔马林固定白暨豚标本线粒体DNA控制区410bp片段。采用了3种预处理方法尽量去除固定标本中残存的甲醛,从试验结果来看,从酒精梯度 临界点干燥处理的标本中提取的DNA在扩增时具有明显优势。通过蛋白酶K消化过程中对于酶的浓度、温浴时间的比较试验,发现随着采用大幅提高酶浓度、延长消化时间等高强度的蛋白酶消化操作后,DNA的质量和产量均得到显著提高。针对标本DNA降解严重的特点,设计特异性好且长度合适的引物以及使用巢式引物扩增,均提高了标本DNA扩增的特异性和灵敏度。通过对所测得的2l头白暨豚线粒体DNA控制区部分序列的对比,发现全部个体在该片段上的序列完全一致,说明白暨豚遗传多样性极低。     

药用前胡研究进展

介绍了中药前胡近10年来的植物资源、化学成分和药理作用的研究成果,详细阐述了其主要药用部位药理作用研究的最新进展.     

重组棉铃虫病毒的外源基因向其他生物的转移

本文报道了基因工程棉铃虫核多角体病毒(HaSNPV-AaIT)的外源蝎子毒素基因(AaIT)是否会向环境中的植物病原微生物或捕食性天敌转移的实验结果。首先,于实验室内将重组病毒HaSNPV-AaIT与棉花黄萎病病菌(VerticilliumdahliaeLleb.)进行了长达90d的混合培养,在混合培养30d,60d和90d后分别提取棉花黄萎病病菌的基因组DNA,用AaIT基因作探针进行点杂交,结果显示无阳性信号。另外,从多次施用过重组病毒的棉花田中采集了120只龟纹瓢虫和七星瓢虫,利用健康蚜虫饲养3-4d,用碱解液处理瓢虫体表后,从处理液中可以检测到病毒DNA;但瓢虫体表经碱解液和Dnase处理后,从瓢虫体内提取的基因组DNA,用PCR和斑点杂交的方法,都没有检测到AaIT的序列存在。本研究的实验结果说明,基因工程病毒的外源基因向其它生物转移的可能性极低。     

表达轮状病毒G2和G3型vp7基因重组腺病毒的免疫效果

为探索以非复制型腺病毒为表达载体的多价轮状病毒(Rotavirus,RV)基因工程疫苗的可行性,在前期工作的基础上,对表达我国G2和G3型RV流行毒株vp7基因的重组腺病毒的免疫效果进行了研究。分别用表达G2和G3型vp7基因的重组腺病毒rvAdG2VP7、rvAdG3VP7经滴鼻和灌胃两种途径免疫Balb/c小鼠,对免疫后小鼠的血清抗体、黏膜抗体和相关的细胞因子水平进行了检测和比较。结果表明,用表达G2和G3型vp7基因的重组腺病毒经滴鼻和灌胃两种途径免疫小鼠后,均可诱导机体产生较强的RV特异性免疫反应,包括体液免疫、细胞免疫和黏膜免疫,并能产生中和抗体。但免疫反应以Th2类为主,Th1类反应也占有相当的比例。本研究为新型RV基因工程疫苗的深入研究奠定了基础。