拟南芥下胚轴伸长与向光性的分子调控机理

下胚轴快速伸长和向光性是高等植物进行固着生活的重要适应性机制,是子叶钻出土层进行光形态发生和光合作用的必要前提。拟南芥下胚轴因其简单的生理形态结构和特异的生理功能而成为剖析植物细胞伸长和向性生长的理想模式系统。本文主要介绍光和植物激素调控拟南芥下胚轴伸长和向光性弯曲的生理基础、遗传学功能及其分子调控机理的最新进展。     

Alterations of chemical composition,construction cost and payback time in needles of Masson pine (Pinus massoniana L.) trees grown under pollution

Previous studies show that Masson pine (Pinus massoniana L.) stands grown at the industrially-polluted site have experienced unprecedented growth decline, but the causal mechanisms are poorly understood. In this study, to understand the mechanisms of growth decline of Mason pine strands under pollution stresses, we determined the reactive oxygen species levels and chemical composition of the current-year (C) and one-year-old (C + 1) needles, and calculated the needle construction costs (CC_mass) of Masson pine trees grown at an industrially-polluted site and an unpolluted remote site. Pine trees grown at the polluted site had significantly higher levels of hydroxyl radical and superoxide anion in their needles than those grown at the unpolluted site, and the former trees eventually exhibited needle early senescence. The contents of lipids, soluble phenolics and lignins in C and C + 1 needles were significantly higher at the polluted site than at the unpolluted site, but the total amounts of non-construction carbohydrates were lower in non-polluted needles than in polluted needles. Elevated levels of the reactive oxygen species and early senescence in polluted needles together led to significant increases in CC_mass and a longer payback time. We infer that the lengthened payback time and needle early senescence under pollution stress may reduce the Masson pine tree growth and consequently accelerate tree decline.     

Gene cloning,expression and characterisation of a new β-agarase,AgWH50C,producing neoagarobiose from Agarivorans gilvus WH0801

agWH50C, a novel β-agarase gene, was cloned from Agarivorans gilvus WH0801 by degenerate PCR and nested PCR. The gene agWH50C comprized a 2,223-bp, encoding a protein of 740 amino acids. Sequencing results demonstrated that AgWH50C shared 45 % sequence identity with a well characterized β-agarase, Aga50D, from Saccharophagus degradans 2–40. The mature agarase was expressed in Escherichia coli and purified by affinity chromatography. The optimum pH and temperature for AgWH50C activity were 6.0 and 30 °C. The K _m and V _max values for agarose were 12.55 mg/ml and 1.17 U/mg. Analysis of the hydrolysis products using linear ion trap mass spectrometry, Fourier transform-nuclear magnetic resonance spectrometry and thin-layer chromatography confirmed that the reaction product of AgWH50c was α-neoagarobiose alone. Therefore, our novel agarase has the potential for industrial applications to produce neoagarobiose as well as provides a key β-agarase for fermentation of agar biomass.     

突触囊泡循环障碍与帕金森病

帕金森病是人类第二大神经退行性疾病,虽然通过对帕金森病遗传家族的研究已发现不少与之相关的致病基因,然而其病因尚不清楚。在已发现的与帕金森病相关基因中,α-synuclein、LRRK2、Parkin、PINK1以及DJ-1也在调节神经元突触前囊泡的神经递质释放以及突触前囊泡循环过程中发挥重要作用。最近的一些研究表明突触前囊泡循环障碍在帕金森病发病过程中扮演重要角色。本文对上述基因在突触囊泡循环以及其突变导致帕金森病病程中的作用作一概述,并推测囊泡循环障碍在帕金森病发病过程中的作用机理,最后指出目前在该研究领域需要解决的一些问题。     

线虫全基因组RNAi筛选确定CAB-1为特异性调节致密核心囊泡分泌的因子

内分泌细胞和神经细胞通过释放激素和神经肽类物质来响应外界刺激,而这些物质的分泌,都是通过致密核心囊泡(dense core vesicle,DCV)来实现的.但是,现阶段关于DCV的生成、转运、释放的机制很大程度上是不清楚的.在本研究中,我们将线虫的排便行为和肠道分泌联系起来,并以此表型进行全基因组RNAi筛选,寻找调节DCV的新基因.我们成功筛选到了一些在肠道调节DCV生成或释放的基因.其中,CAB-1被确认为特异性调节DCV分泌的重要因子.在肠道中,cab-1突变会降低肠道DCV内容物的分泌,而在神经系统中,CAB-1的缺失也会导致DCV的标识物堆积在突触前,而突触囊泡(synaptic vesicle,SV)不受影响.     

种间转移扩增筛选仙湖苏铁微卫星位点及其遗传多样性研究

运用刺叶苏铁、葫芦苏铁、海南苏铁的SSR引物,在仙湖苏铁中进行种间转移扩增,筛选得到7对引物能扩增出清晰的特异带,其中3对引物的扩增产物具有多态性.为验证微卫星的真实性,扩增产物切胶回收后克隆测序.结果表明：重复单元的数目变化是扩增片段长度多态性的主要来源.运用筛选出的3对 SSR标记对4个仙湖苏铁野生种群进行遗传结构研究,等位基因数从2~5,杂合度从0．000~0．667,期望杂合度为0．000~0．610.种群两两遗传分化系数从0~0．382.总体上仙湖苏铁遗传多样性水平低,而种群间遗传分化显著.STRUCTURE分析结果表明,4个野生种群可被分配到3个假想的遗传簇.BOTTLENECK 分析结果表明种群近期没有遭遇瓶颈效应.     

不同互花米草治理措施对植物与大型底栖动物的影响简

治理外来入侵植物互花米草(Spartina alterniflora)对保护河口湿地鸟类栖息地及生物多样性具有重要意义。研究在崇明东滩比较了"淹水刈割"、"反复刈割"及"化学除草"三种措施对大面积互花米草的治理效果及其对大型底栖动物与土著植物芦苇(Phragmites australis)的影响。结果表明,反复刈割措施对互花米草生长具有一定的控制作用,对底栖动物群落的影响较小;使用化学除草剂清除互花米草的效果不明显,对底栖动物群落的影响亦不明显;淹水刈割措施能长期有效地清除互花米草,但长期淹水对底栖动物群落的影响较大,同时亦对芦苇生长造成一定负面影响。因此,淹水刈割可能是在河口生态系统治理大面积互花米草最有效的方法,但是在后续管理中需要采取一定的措施来减小对底栖动物及土著植物的影响。