兔眼越桔花粉的超微结构和营养成分与其育性关系研究

运用透射电镜观察5个兔眼越桔品种的花粉结构并分别测定分析了花粉的营养成分,以探讨兔眼越桔花粉育性与其超微花粉结构和营养成分的关系.结果表明,兔眼越桔花粉结构中,内膜系统清晰可见,发育程度因品种而异.开花前的花粉细胞核仁较大,蛋白质合成旺盛.对花粉超微结构与营养成分间关系的比较分析表明:花粉细胞的全糖和脯氨酸含量与花粉发芽率呈正相关,兔眼越桔花粉壁的厚度、花粉细胞的蛋白质含量与花粉的萌发率无相关性,而内质网发育程度与蛋白质含量呈正相关趋势.推测兔眼越桔花粉细胞的全糖和脯氨酸含量对兔眼越桔花粉的发育及其育性具有密切的关系.     

Fixed‐effect variance and the estimation of repeatabilities and heritabilities: issues and solutions

Linear mixed‐effects models are frequently used for estimating quantitative genetic parameters, including the heritability, as well as the repeatability, of traits. Heritability acts as a filter that determines how efficiently phenotypic selection translates into evolutionary change, whereas repeatability informs us about the individual consistency of phenotypic traits. As quantities of biological interest, it is important that the denominator, the phenotypic variance in both cases, reflects the amount of phenotypic variance in the relevant ecological setting. The current practice of quantifying heritabilities and repeatabilities from mixed‐effects models frequently deprives their denominator of variance explained by fixed effects (often leading to upward bias of heritabilities and repeatabilities), and it has been suggested to omit fixed effects when estimating heritabilities in particular. We advocate an alternative option of fitting models incorporating all relevant effects, while including the variance explained by fixed effects into the estimation of the phenotypic variance. The approach is easily implemented and allows optimizing the estimation of phenotypic variance, for example by the exclusion of variance arising from experimental design effects while still including all biologically relevant sources of variation. We address the estimation and interpretation of heritabilities in situations in which potential covariates are themselves heritable traits of the organism. Furthermore, we discuss complications that arise in generalized and nonlinear mixed models with fixed effects. In these cases, the variance parameters on the data scale depend on the location of the intercept and hence on the scaling of the fixed effects. Integration over the biologically relevant range of fixed effects offers a preferred solution in those situations.     

Protochlorophyllide forms in non-greening epicotyls of dark-grown pea (Pisum sativum)

Low-temperature fluorescence emission spectra of 6.5-day-old dark-grown epicotyls of pea ( Pisum sativum ) revealed the presence of protochlorophyll(ide). The upper part of the epicotyl contained 30% of the protochlorophyll(ide) content per fresh weight found in pea leaves, whereas the lower part contained 3%. Three discrete spectral forms of protochlorophyll(ide) were clearly distinguished after Gaussian deconvolution of fluorescence excitation and emission spectra. Adding the satellite bands of the Qy_(0-0) transitions (the emission vibrational (Emv) bands with correlated amplitudes, gave the following delineation: Ex439–Em629–Emv684, Ex447–Em636–Emv700 and Ex456–Em650–Emv728. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) followed by immunodetection of whole tissue extracts of the epicotyl indicated the presence of NADPH-protochlorophyllide oxidoreductase (EC 1.3.1.33). Electron micrographs showed prolamellar bodies in at most 11 % of the plastid profiles of the epicotyl cells. These prolamellar bodies were smaller, and many of them showed less regular structure than those of the leaves. Taken together, the results indicate that the protochlorophyll(ide) in epicotyls is arranged in a different way than in leaves.     

Intracellular trafficking and degradation of unassociated proalpha2 chains of collagen type I

Procollagen I is a trimer consisting of two proalpha1(I) chains and one proalpha 2(I) chain. In certain cases of mild osteogenesis imperfecta, abnormal proalpha1(I) chains are degraded very soon after synthesis. As a consequence, the cells produce excess proalpha2(I) chains, which cannot form trimers and are not secreted. The objective of this work was to determine the intracellular fate of unassociated proalpha2(I) chains. Mov13 mouse fibroblasts, which do not synthesize proalpha1(I) mRNA, but do produce proalpha2(I) mRNA, were incubated with radioactive amino acids using pulse-chase protocols, and proteins were analyzed by gel electrophoresis, autoradiography, and Western blotting. Mov13 cells produced proalpha2(I) chains that were degraded intracellularly within 30 min. Degradation was inhibited when cells were treated with brefeldin-A, which blocks transit from endoplasmic reticulum to Golgi. Fixed cells exposed to various immunofluorescence markers and imaged by confocal laser scanning microscopy showed that proalpha2(I) chains colocalized with Golgi and lysosome markers. Degradation was inhibited and chains were secreted when cells were treated with wortmannin, which blocks trafficking to lysosomes. These results demonstrate that unassociated proalpha2(I) chains leave the endoplasmic reticulum, transit the Golgi, and enter lysosomes where they are degraded.     

应用排序分析藓类植物分类群分布与气候因素的关系

以我国21个山地藓类植物区系和气象资料为基础,应用典范对应分析(CCA)和除趋势典范对应分析(DCCA),比较了21个山地中藓类植物61个科,曲尾藓科(Dicranaceae)23个属、曲柄藓属(Campylopus)17种及曲尾藓属(Dicranum)35种分布与年均温度、>10℃积温、1月均温、7月均温、年均相对湿度、年均降雨量、年有雾天数、年有霜天数和年日照时数的关系,通过排序进行了直观的展示;同时还应用典范对应分析直观地反映了包括长白山在内的我国9个山地苔藓植物地理成分组成上的相似性及它们与气候因素间的关系.本文研究表明将DCCA和CCA应用到植物区系地理学研究上是可行的.     

体外多酶分子机器的现状和最新进展

体外多酶分子机器遵循所设计的多酶催化路径,将若干种纯化或部分纯化的酶元件进行合理的优化与适配,高效地在体外将特定的底物转化为目标化合物。体外多酶分子机器反应系统呈现元件化和模块化的特点,在设计、组装和调控方面具有较高的自由度。近年来,体外多酶分子机器在实现反应过程的精准调控和提高产品得率方面的优势逐渐体现,展示了其在生物制造领域重要的应用潜力。对体外多酶分子机器的相关研究已成为合成生物学的一个重要分支领域,日益受到广泛的关注。文中系统地综述了基于酶元件/模块的体外多酶分子机器的构建策略,以及改善该分子机器中酶元件/模块之间适配性的研究进展,并分析了该生物制造平台的发展前景与挑战。     

Organization and assembly of the TRAPPII complex

Current models suggest that TRAPP tethering complexes exist in two forms. Whereas the seven-subunit TRAPPI complex mediates ER-to-Golgi transport, TRAPPII contains three additional subunits (Trs65, Trs120 and Trs130) and is required for distinct tethering events at Golgi membranes. It is not clear how TRAPPII assembly is regulated. Here, we show that Tca17 is a fourth TRAPPII-specific component, and that Trs65 and Tca17 interact with distinct domains of Trs130 and make different contributions to complex assembly. Whereas Tca17 promotes the stable association of TRAPPII-specific subunits with the core complex, Trs65 stabilizes TRAPPII in an oligomeric form. We show that Trs85, which was previously reported to be a subunit of both TRAPPI and TRAPPII, is not associated with the TRAPPII complex in yeast. However, we find that proteins related to Trs85, Trs65 and Tca17 are part of the same TRAPP complex in mammalian cells. These findings have implications for models of TRAPP complex formation and suggest that TRAPP complexes may be organized differently in yeast and mammals.     

不同植物生长调节剂对中华猕猴桃扦插生根的影响

以中华猕猴桃"桂海4号"为试材,采用500mg·L-1、1000mg·L-1、1500mg·L-1三种不同浓度的吲哚丁酸、萘乙酸、和ABT生根粉处理插条,进行了猕猴桃扦插试验。结果表明:吲哚丁酸1500mg·L-1的扦插生根率极显著高于萘乙酸和ABT生根粉的各个处理,显著高于吲哚丁酸1000mg·L-1;吲哚丁酸对根数和根长的促进作用优于萘乙酸和ABT生根粉,ABT生根粉对于根粗的促进作用却较其它两者强;主成分分析结果表明,吲哚丁酸1500mg·L-1处理的插条生长情况最好。     

Caffeine inhibition of cytokinesis: Ultrastructure of cell plate formation/degradation

Summary Caffeine is a potent inhibitor of cell plate formation in dividing plant cells. Previous studies living cells reveal that the drug always permits the cell plate to arise and grow normally until about 80% complete, but then causes it to break down. In the present investigation we examine this formation/degradation cycle at the ultrastructure level. Our results show that during the formation phase the caffeine treated plate is indistinguishable from untreated controls. Phragmoplast microtubules arise and align in the interzone, Golgi vesicles are produced and aggregate in a line that defines the young cell plate, and considerable fusion of these vesicles occurs to form islands of plate material. However, under the influence of caffeine these islands do not fuse to form the enlarged lamellar expanses characteristic of maturing cell plates. Instead, the partially fused material reverts to small vesicles which appear to become resorbed by the cellular membrane systems. The resorption process continues leaving no evidence of the previously developing plate, although occasionally we observe a stub of fused vesicles attached to the parent wall. Following cell plate disintegration the reformed nuclei move close together and occupy the central region of the cell. These observations focus attention on the consolidation phase of cell plate formation as the one being maximally affected by caffeine.Dedicated to the memory of Professor Oswald Kiermayer