森林凋落物的微生物分解

森林凋落物的分解是森林生态系统中物质循环和能量流动的一个重要环节,而微生物在这一过程中起着重要作用。本文系统介绍了森林凋落物微生物分解的过程及其生态学意义,并从参与凋落物分解的微生物多样性、凋落物分解过程中的微生物数量动态及群落演替、影响微生物分解的因素及微生物分解酶学等方面综述了森林凋落物的微生物分解研究概况,探讨了未来研究的方向。     

转反义Wx基因水稻颖果中与淀粉合成和积累相关酶活性的变化

将反义Wx基因转入水稻,导致Wx蛋白不同程度减少,颖果中的直链淀粉含量不同程度下降,总淀粉含量显著降低,直链淀粉与总淀粉的比值极显著降低。在水稻颖果发育过程中,ADPG-PPase、GBSS、SSS和SBE的活性在灌浆前期迅速升高,达最大值后很快下降,在灌浆中后期下降趋缓。Wx蛋白减少后的转基因水稻颖果中的GBSS活性明显下降,下降幅度与直链淀粉含量相一致,而且活性高峰期比其亲本有所提前。转基因水稻颖果中ADPG-PPase和SSS的活性在颖果发育的前中期,SBE则在中后期高于相应的亲本。     

高压静电场对植物生物学效应的研究进展

本文系统阐述了高压静电场对植物的生物学效应。主要包括高压静电场对种子和植株的影响,对愈伤组织及果蔬保鲜的影响也进行了探讨。然后着重从酶活性、膜通透性、胞内水分子状态、遗传变异、物质代谢五个方面分析了高压静电场对植物影响的机理。同时对从机理方面研究高压静电场的生物学效应及高压静电场的应用进行了讨论和展望。     

Temperature-independent diel variation in soil respiration observed from a temperate deciduous forest

The response of soil respiration (R_s) to temperature depends largely on the temporal and spatial scales of interest and how other environmental factors interact with this response. They are often represented by empirical exponential equations in many ecosystem analyses because of the difficulties in separating covarying environmental responses and in observing below ground processes. The objective of this study was to quantify a soil temperature‐independent component in R_s by examining the diel variation of an R_s time series measured in a temperate deciduous forest located at Oak Ridge, TN, USA between March and December 2003. By fitting 2 hourly, continuous automatic chamber measurements of CO₂ efflux at the soil surface to a Q₁₀ function to obtain the temperature‐dependent respiration (R_t) and plotting the diel cycles of R_t, R_s, and their difference (R_i), we found that an obvious temperature‐independent component exists in R_s during the growing season. The diel cycle of this component has a distinct day/night pattern and agrees well with diel variations in photosynthetically active radiation (PAR) and air temperature. Elevated canopy CO₂ concentration resulted in similar patterns in the diel cycle of the temperature‐independent component but with different daily average rates in different stages of growing season. We speculate that photosynthesis of the stand is one of the main contributors to this temperature‐independent respiration component although more experiments are needed to draw a firm conclusion. We also found that despite its relatively small magnitude compared with the temperature‐dependent component, the diel variation in the temperature‐independent component can lead to significantly different estimates of the temperature sensitivity of soil respiration in the study forest. As a result, the common practice of using fitted temperature‐dependent function from night‐time measurements to extrapolate soil respiration during the daytime may underestimate daytime soil respiration.     

Relationship between body size and homing ability in the genus Osmia (Hymenoptera; Megachilidae)

Abstract 1. The maximum homing ability of female bees, that is, their capacity to return to the nest after being displaced a certain distance, is considered to be an estimate of their maximum foraging distance. 2. The present study provides data on homing ability and body weight for Osmia lignaria and combines them with data for five other congenerics, O. rufa, O. cornuta, O. pedicornis, O. cornifrons, and O. emarginata for analysis. These species are important pollinators of spring‐flowering plants, and some have been developed as commercial crop pollinators. 3. It is shown that homing ability is positively and linearly related to body weight (r² = 0.81; P = 0.01). 4. These results should be of use in selecting Osmia species as potential crop pollinators and establishing adequate buffer distances around genetically modified crops.     

魏氏拟尾柱虫休眠包囊及其细胞器超微结构的观察

为研究纤毛虫休眠状态下细胞的分化及其胞器的特征,本文以透射电镜术显示,魏氏拟尾柱虫（Ｐａｒａｕｒｏｓｔｙｌａｗｅｉｓｓｅｉ）休眠包囊中,颗粒层壁内有小泡,表膜位置偶见小泡样结构,大部分线粒体以多个相互聚集在一起,自噬泡将线粒体等胞器包裹在内经历消化过程,细胞内膜系统十分发达。作者推测,颗粒层及表厝小泡可能是休眠细胞经由表膜进行物质交换的结构,自噬泡消化现象可能是细胞中物质和能量来源的主要途径。     

应用大规模测序技术和生物信息学研究造血干/祖细胞的基因表达及新基因 的识别和克隆

从新生儿脐血和成人骨髓中分选出造血干/祖细胞(HSC/HPC),构建成cDNA文库,对其进行大规模表达序列标签(EST)测序,通过生物信息学等手段分析基因表达谱,并进行新基因的全长cDNA克隆。在所测的10512条可分析E ST序列中,有9866条来自脐血CD34+|细胞,其中4697条(47.6%)为已知基因,2603条(26.4%)为已知EST,1415条(14.3%)代表未知EST。在已知基因中,8.2%基因与造血相关,22.7%涉及细胞代谢、结构和迁移,13.0%与细胞分裂和防御相关,26.2%与RNA、蛋白质的合成相关,10.6%和细胞信号传递有关。对一些已知和未知的EST,综合测序、生物信息学等方法,进行全长克隆,已获得23个新基因的全长cDNA。 Abstract:Hematopoietic stem/progenitor cells were isolated from umbilical cord blood and adult bone marrow,and subject to cDNA library construction.The gene expression pattern in CD34+ cells and the identification and cloning of novel genes were performed by sequencing ESTs and analyzing them with the tools of bioinformatics.Among the obtained 10 512 ESTs which could be further analyzed,9,866 were from umbilical cord blood where 4 697(67.6%)were known genes,2 603(26.4%)were known ESTs and 1415(14.3%)represented novel ESTs.Within the identified genes,8.2% was involved in hematopoiesis,22.7% was associated with cell metabolism,structure and mobility,13.0% was linked to cell division and defence,26.2% was related to RNA protein synthesis and 10.6% was related with cell signal transduction.In parallel,we developed an efficient working system combining sequencing,bioinformatics,etc.and obtained 23 full-length cDNAs from both known and novel ESTs identified in this work.     

中国红豆杉属及其近缘植物的遗传变异和亲缘关系分析

采用水平式淀粉凝胶电泳技术,对中国产红豆杉属Taxus 3种1变种以及白豆杉Pseudotaxus chienii共12个居群的遗传多样性进行了检测。对7个酶系统9个酶位点的分析结果表明,红豆杉属和 白豆杉的种内遗传多样性水平较高,各类群的多态位点比率(P)为44.4％～77.8％,等位基因平均数 (A)为1．6～2．1,平均期望杂合度(He)和实际观察杂合度(Ho)分别为0.065～0.152和0.068～0.111。 根据对等位酶实验结果的分析,结果表明除云南红豆杉T．yunnanensis与红豆杉属其它几个种的遗传 一致度稍低(I=0.727～0.804)外,红豆杉属的其它几个种的遗传一致度较高(0.906～0.995),体现其 亲缘关系很近。笔者建议将红豆杉属的这几个种合并为一个种,并根据地理分布及不同生境发生的变 异在种下设地理宗。同时根据等位酶的实验分析结果,白豆杉和红豆杉属各种的比较有显著差异,支持白豆杉作为单独属Pseudotaxus的处理。     

水稻随体染色体的研究

分析了几种野生稻种及栽培稻品种随体染色体的数目,发现不同染色体组型的稻种之间随体染色体数目有一定差异,其中染色体组ＡＡ的有１～２对,随体染色体因品种或样本的来源而异,染色体组ＢＢ的有３对随体染色体,染色体组ＣＣ的有２对随体染色体,染色体组型为ＢＢＣＣ的Ｏｒｙｚａｍｉｎｕｔａ可能有４对随体染色体,而染色体组型为ＣＣＤＤ的Ｏ．ｌａｔｉｆｏｒｉａ则有２对随体染色体。在栽培稻中,不同品种之间随体染色体的数目也存在差异,一般而言,籼稻品种具有两对随体染色体,分别为第１０和第１２染色体,粳稻品种只有一时随体染色体,为第１０染色体。