The division of endosymbiotic organelles

Mitochondria and chloroplasts are essential eukaryotic organelles of endosymbiotic origin. Dynamic cellular machineries divide these organelles. The mechanisms by which mitochondria and chloroplasts divide were thought to be fundamentally different because chloroplasts use proteins derived from the ancestral prokaryotic cell division machinery, whereas mitochondria have largely evolved a division apparatus that lacks bacterial cell division components. Recent findings indicate, however, that both types of organelles universally require dynamin-related guanosine triphosphatases to divide. This mechanistic link provides fundamental insights into the molecular events driving the division, and possibly the evolution, of organelles in eukaryotes.     

甘蔗叶绿体分离及其蛋白质提取方法研究

【目的】探索甘蔗幼苗叶片完整叶绿体的分离纯化及其叶绿体蛋白质提取方法,为深入研究甘蔗叶绿体蛋白质组学奠定基础。【方法】以甘蔗品种ROC22幼苗叶片为材料,通过差速离心法制备粗叶绿体制品,分别利用蔗糖密度梯度离心和Percoll梯度离心进一步分离纯化完整叶绿体;提取叶绿体蛋白质,并进行电泳分析。【结果】两种密度梯度离心法均可获得纯度和完整率较高的叶绿体,但蔗糖密度梯度离心法具有分离时间较短、成本较低,分离的叶绿体完整率、纯度和含量高等特点,并且提取的叶绿体蛋白质电泳条带清晰,蛋白质数量多且较全。【结论】与Pecoll梯度离心法相比,蔗糖密度梯度离心法更适宜于在亚细胞水平上进行甘蔗蛋白质组学研究。     

甘蔗叶绿体分离及其蛋白质提取方法研究

【目的】探索甘蔗幼苗叶片完整叶绿体的分离纯化及其叶绿体蛋白质提取方法,为深入研究甘蔗叶绿体蛋白质组学奠定基础。【方法】以甘蔗品种ROC22幼苗叶片为材料,通过差速离心法制备粗叶绿体制品,分别利用蔗糖密度梯度离心和Percoll梯度离心进一步分离纯化完整叶绿体;提取叶绿体蛋白质,并进行电泳分析。【结果】两种密度梯度离心法均可获得纯度和完整率较高的叶绿体,但蔗糖密度梯度离心法具有分离时间较短、成本较低,分离的叶绿体完整率、纯度和含量高等特点,并且提取的叶绿体蛋白质电泳条带清晰,蛋白质数量多且较全。【结论】与Pecoll梯度离心法相比,蔗糖密度梯度离心法更适宜于在亚细胞水平上进行甘蔗蛋白质组学研究。     

A selective activity-dependent requirement for dynamin 1 in synaptic vesicle endocytosis

Dynamin 1 is a neuron-specific guanosine triphosphatase thought to be critically required for the fission reaction of synaptic vesicle endocytosis. Unexpectedly, mice lacking dynamin 1 were able to form functional synapses, even though their postnatal viability was limited. However, during spontaneous network activity, branched, tubular plasma membrane invaginations accumulated, capped by clathrin-coated pits, in synapses of dynamin 1-knockout mice. Synaptic vesicle endocytosis was severely impaired during strong exogenous stimulation but resumed efficiently when the stimulus was terminated. Thus, dynamin 1-independent mechanisms can support limited synaptic vesicle endocytosis, but dynamin 1 is needed during high levels of neuronal activity.     

Uptake of isolated chloroplasts by mammalian cells

Mouse fibroblasts (L cells) in suspension culture incorporated isolated chloroplasts of spinach and African violets and isolated mitochondria of chicken liver. The organelles resided in the cell cytoplasm and were not contained in vacuoles or digestion vesicles. Green cells divided like normal cells. Green chloroplasts were followed for five cell generations or 5 days, at which time hybrid cells were greatly outnumbered by nongreen progeny cells. The ingested chloroplasts retained their structural integrity as determined by electron microscopy of organelles and hybrid cells and by analysis of photochemical activity and DNA in chloroplasts reisolated from cells after 1 or 2 days in culture.     

Ultrastructural studies of seed coat and cotyledon during rapeseed maturation

Brassica napus L.(B. napus) is an important oil crop worldwide and it rapidly accumulates oil at late stage of seed maturation. However, little is known about the cellular mechanism of oil accumulation and seed color changes during the late stage of rapeseed development. Here, we analyzed the ultrastructure of seed coat, aleurone and cotyledon in embryos of B. napus from 25 to 70 days after flowering(DAF). The pigments, which were deposited on the cell wall of palisade cells in seed coat, determined dark black color of rapeseed. The chloroplasts degenerated into non-photosynthetic plastids which caused the green cotyledon to turn into yellow. The chloroplasts in aleurone and cotyledon cells respectively degenerated into remnants without inner and outer envelope membranes and ecoplasts with intact inner and outer envelope membranes. From 40 to 70 DAF, there were degraded chloroplasts without thylakoid, oil bodies contacting with plastids or protein bodies, big starch deposits of chloroplasts degrading into small particles then disappearing, and small endoplasmic reticulum(ER) in aleurone and cotyledon cells. Additionally, there were decreases of chlorophyll content and dramatic increases of oil content in rapeseed. These results suggested that the rapid oil accumulation was independent on the NADPH synthesized by photosynthesis of chloroplasts and probably utilized other sources of reductant, such as the oxidative pentose phosphate pathway during the late stage of rapeseed development. The triacylglycerol assembly presumably utilizes the enzymes in the plastid, cytosol or oil body of cotyledon and aleurone cells.     

受甘蔗花叶病毒侵染后甘蔗叶片及其叶绿体中ATPase活性的变化

采用ATPase活性的常规测定方法,研究了7个不同甘蔗品种感染甘蔗花叶病毒株系A(SCMV-A)后叶片及其叶绿体中Mg~(2+)-ATPase和Ca~(2+)-ATPase活性的变化.结果表明:闽糖70/611,F134,闽选703,福引79/8,福引79/9,NCo310和Co740等7个品种染病后,叶片中Ca~(2+)-ATPase和Mg~(2+)-ATPase活性均显著高于其相应的健株;叶绿体中Mg~(2+)-ATPase活性也呈现相同的趋势,而Ca~(2+)-ATPase活性则差异不显著.然而病株叶片叶绿体之外部分的Ca~(2+)-ATPase和Mg~(2+)-ATPase活性均显著高于其相应的健株.这表明SCMV—A对叶片、叶绿体及叶绿体以外部分的Mg~(2+)-ATPase和Ca~(2+)-ATPase活性均有影响.     

用焦锑酸钾技术研究玉米叶片中的钙

应用改良的焦锑酸钾沉淀技术,研究了玉米叶绿体钙的亚细胞定位和缺钙对玉米叶片细胞结构的影响,结果表明,在玉米两种叶绿体的被膜、片层结构和基质中均有锑酸钙沉淀存在,其中的基粒类囊体和基质类囊体具有较高的钙水平.研究结果还表明,缺钙会引起玉米叶片维管束鞘细胞、筛管分子、伴胞和叶肉细胞内与膜结合的钙离子释放出来,呈不规则的锑酸钙沉淀散布在细胞内,同时使细胞的内膜结构(如内质网、液泡等)遭到破坏而解体,随着缺钙程度的加深,叶绿体的片层结构开始解体.这说明钙对叶绿体的功能和维持细胞膜结构的完整性起着重要的作用.     

辐射诱发兰花叶艺突变体的叶片叶肉细胞超微结构观察

以未经辐射的全绿植株(TRIR-1)和经辐射诱发叶艺兰植株(TRIR-2)的叶肉细胞为试材,对其全绿植株叶片的正常绿色区、辐射诱变植株叶片的绿色区(TRIR-2′)和白色区(TRIR-2″)叶片叶肉细胞进行细胞超微结构观察。结果表明:(1)TRIR-1叶肉细胞中叶绿体数量最多,TRIR-2′次之,TRIR-2″中无成熟完整的叶绿体;(2)TRIR-1叶肉细胞中的线粒体呈椭圆颗粒状,TRIR-2′中的线粒体外膜破裂、线粒体溶解、嗜锇颗粒数量最多,TRIR-2″中有少量外膜完整的线粒体;(3)TRIR-2″部分叶肉细胞中无细胞器,只有少量细胞质。说明经辐射诱变叶艺兰与未经辐射植株叶肉细胞结构存在差异。     

谷子[Setaria italica(L.)Beauv.]光合特性的分析——叶片解剖和叶绿体亚显微结构的特征

为了研究谷子[Setaria italica(L·)Beauv·]的光合作用碳素同化途径,本文对该植物的叶片解剖特征和细胞亚显微结构做了观察。试验结果表明: (1) 谷子具有典型的Kranz型叶解剖特征。 (2) 谷子叶片中存在着二形叶绿体。MC叶绿体含有清晰的基粒和周质网,而VBS叶绿体没有基粒,但是有大量的淀粉粒。这两方面都显示了C_4植物的特征。本文对有关的文献做了综述,从七个方面确定谷子是C_4植物:①光合初产物以四碳二羧酸为主;②Kranz型叶解剖特征和窄的叶脉间距;③二形叶绿体和周质网;④高的~(13)C/~(12)C比值;⑤PEPC和RuBPC的活性水平,分室隔离以及光合代谢中间产物对VBS叶绿体固定COz作用的促进和抑制;⑥低光呼吸;⑦较高的光合强度。谷子光呼吸和与光呼吸有关的生理指标基本符合C_4特征,但稍高于典型C_4植物的水平,这可能和谷子是温带起源的C_4种有关。它在进化过程中所迂到的温度和光照条件对降低光呼吸作用的进化压力相对比热带环境的要小一些。谷子受现代育种技术的影响还比较少。当前应以改善植株的形态特征和扩充结实器官的容纳能力,提高经济系数作为进一步直接提高光合效率的育种基础。     

我国茶园管理机械化技术研究进展

综述了我国茶园垦殖动力和机械、茶园土肥管理机械、茶园灾害管理机械、茶树管理机械等茶园管理机械化技术现状,指出其存在问题与发展方向,并根据我国茶产业现状提出开展茶园管理机械化技术集成和推广的设想。     

不同海拔高度的烤烟淀粉合成动态研究

对云烟87在贵州毕节地区不同海拔高度、不同发育时期叶片的超微结构、淀粉含量、淀粉合成相关基因的表达进行研究。结果表明:移栽后35-50 d(移栽前期)高海拔地区烟叶淀粉含量稍高,颗粒结合型淀粉合成酶基因(GBSSI)和淀粉分支酶基因(SBE)的表达较强,但叶绿体淀粉粒超微结构无明显差异;移栽后65-95 d,淀粉含量急剧增加,叶绿体淀粉粒体积和数量均增加,GBSSI和SBE的表达也较强;移栽后95 d,高海拔地区烟叶叶绿体已充分降解,中海拔地区的开始降解,低海拔地区叶绿体仍保持完整;一定海拔范围内,在烟叶发育前期,海拔高度越高,淀粉积累越多,发育后期高海拔地区烟叶叶绿体降解充分,且GBSSI和SBE的表达减弱,说明高海拔导致淀粉含量减少。     

A circadian output in Drosophila mediated by neurofibromatosis-1 and Ras/MAPK

Output from the circadian clock controls rhythmic behavior through poorly understood mechanisms. In Drosophila, null mutations of the neurofibromatosis-1 (Nf1) gene produce abnormalities of circadian rhythms in locomotor activity. Mutant flies show normal oscillations of the clock genes period (per) and timeless (tim) and of their corresponding proteins, but altered oscillations and levels of a clock-controlled reporter. Mitogen-activated protein kinase (MAPK) activity is increased in Nf1 mutants, and the circadian phenotype is rescued by loss-of-function mutations in the Ras/MAPK pathway. Thus, Nf1 signals through Ras/MAPK in Drosophila. Immunohistochemical staining revealed a circadian oscillation of phospho-MAPK in the vicinity of nerve terminals containing pigment-dispersing factor (PDF), a secreted output from clock cells, suggesting a coupling of PDF to Ras/MAPK signaling.     

寒冷地区作业机械密封件性能的研究

在我区林区，因冬季气候寒冷，许多机械的密封件极易损坏，从而影响生产，增加维修费用。本文通过对现有密封件结构的试验分析，找出其易损坏的主要原因，并提出了结构改迸措施，从而解决了在寒冷条件下作业机械的密封件易损问题。     

葡萄落叶前叶片细胞亚显微结构的变化

电子显微镜观察结果表明，生长季山葡萄与玫瑰香叶片细胞亚显微结构无明显差异．随着秋季温度的降低，山葡萄叶绿体相互聚集，片层结构稳定，内部淀粉植减少见脂滴增加；液泡膜内陷，形成一些吞噬泡。落叶前，玫瑰香叶绿体中的淀粉粒亦减少，脂滴有增加的趋势，但片层结构清晰度明显下降，末见叶绿体聚集和吞噬泡的形成。     

银丝竹不同叶色叶绿素合成及叶结构差异

为探明银丝竹叶色差异的原因,对银丝竹不同叶色叶片的光合色素含量、 叶绿素合成前体相对含量及叶片显微和超微结构进行研究.结果表明:1)银丝竹不同叶色间的光合色素含量存在显著差异,其含量随着绿色叶片面积的下降而下降;2)银丝竹叶片出现白色性状的原因在于其叶绿素生物合成过程受阻,受阻点可能位于粪卟啉原Ⅲ至原卟啉原Ⅸ的转化过程中;3)两种叶色叶片表皮细胞无明显差异,但白色叶肉细胞中内容物明显缺失;4)绿色叶肉细胞中具有丰富而完整的叶绿体结构,而白色叶肉细胞中呈现出叶绿体膜结构模糊,无完整边界等形态,基粒类囊体片层不规则或呈空泡状,在多数细胞内可见较明显的嗜锇颗粒.本研究从生理层面初步解释了银丝竹叶色差异的原因,为进一步开展相关分子机理研究奠定了基础.     

农牧户家庭种植业生产经营行为影响因素分析——以西藏典型县(市)为例

选用全国农村固定观察点西藏地区那曲、堆龙德庆、日喀则3县(市)的204个面板数据样本,采用线性模型和混合OLS模型以及随机效应模型回归估计方法,针对影响农牧户种植业生产行为的因素进行了系统分析。研究表明,"外出打工人员数量"、"家庭劳动力数量"、"年末拥有生产性固定资产原值"、"是否拥有农业机械"等家庭禀赋因素对于家庭的总播种面积具有正向影响,理论上预测的内部因素禀赋效应成立;"粮食均价"与"是否出售"这两个因素的乘积具有显著的影响作用,实证结果证实外部因素中价格的替代效应大于收入效应。     

毛丛弯曲频率与中国美利奴生产性能及羊毛品质相关性的研究

本研究采用方差分析法对中国美利奴《新疆型》主要经济性状和部分羊毛品质与毛丛弯曲频率(每英寸内弯曲数)的相关性进行了研究,并对部分性状进行了多重比较和最小二乘分析。研究结果表明,不同毛丛弯曲频率间中国美利奴初生重、断奶重、断奶毛长、周岁重、周岁污毛量、二岁体重、二岁污毛量、二岁密度、伸直率、单位长度内鳞片数,以及肩、侧、股三个部位的毛丛弯曲频率和后代初生重无显著差异(FF_(0.01)、显著(F>F_(0.05)或比较显著(F>F_(0.10),所反应的规律性基本上是:毛丛弯曲越大,净毛量、净毛率越高,二岁毛长、周岁毛长、羊毛伸直长度越长,强度和相对强度越大;但毛丛弯曲越大,羊毛伸直长度的均匀性和细度的均匀性也越差;伸度以毛丛弯曲频率在10.5～12.5个/英寸之间者最大,但与其它各组间差异并不显著,细度没有表现出随着毛丛弯曲变大,羊毛变粗的趋势。     

水稻矮缩病毒云南、浙江分离株侵染水稻植株的细胞病理比较研究

应用超薄切片电镜技术比较观察RDV云南和浙江分离株侵染水稻植株的细胞病理。RDV云南分离株侵染的水稻叶片中,充满病毒粒体的细胞呈条带状分布,呈现出明显的侵染和增殖中心,在充满病毒粒体的细胞周围,相邻细胞有不同程度的病变,叶绿体膜系统消失,部分叶绿体中含有病毒颗粒,线粒体残体及细胞质中有分散或聚集的病毒粒体,细胞核中未见病毒粒体,离侵染中心较远的细胞中亚细胞结构较完整;RDV浙江分离株侵染的水稻叶片中,部分细胞充满病毒粒体,无明显的条带状分布,其他细胞病理特征与RDV云南分离株侵染的水稻叶片相似。RDV不同分离株侵染寄主植株的细胞病理特征无显著差异,对其致病性的差异需进一步研究。     

An ancient group I intron shared by eubacteria and chloroplasts

Introns have been found in the genomes of all major groups of organisms except eubacteria. The presence of introns in chloroplasts and mitochondria, both of which are of eubacterial origin, has been interpreted as evidence either for the recent acquisition of introns by organelles or for the loss of introns from their eubacterial progenitors. The gene for the leucine transfer RNA with a UAA anticodon [tRNALeu (UAA)] from five diverse cyanobacteria and several major groups of chloroplasts contains a single group I intron. The intron is conserved in secondary structure and primary sequence, and occupies the same position, within the UAA anticodon. The homology of the intron across chloroplasts and cyanobacteria implies that it was present in their common ancestor and that it has been maintained in their genomes for at least 1 billion years.