水稻品种灌浆期耐热性的综合评判

建立了一种对水稻品种的灌浆期耐热性进行综合评判的方法.选取籽粒充实度、秕粒率、饱粒密度、垩白米率、垩白度等5个与水稻灌浆期耐热性强弱密切相关的性状,以参评品种这5个性状的耐热系数为指标,应用主成分分析法将5个彼此相关的单项指标转化为2个累计贡献率达到85%以上的相互独立的综合指标,根据每一品种的5个单项性状的耐热系数和综合指标的标准化特征向量求出每一品种2个综合指标的得分.计算每一品种2个综合指标得分的隶属函数值,并以综合指标的贡献率来确定2个综合指标的权重,在此基础上进行加权求和,从而得到每一品种灌浆期耐热性的综合评判值（D值）.采用系统聚类分析方法对各品种的综合评判值（D值）进行数量分类,同时结合生产实际的要求,可把每一品种划归为不同的耐性等级.外部独立样本组的统计检验以及实践验证的结果表明,所建立的综合评判方法具有理想的效果,可以对不同品种灌浆期综合耐热性能的强弱作出客观、准确的评判.     

Dynamic lipidomic insights into the adaptive responses of Saccharomyces cerevisiae to the repeated vacuum fermentation

Vacuum fermentation is utilized in a wide range of life science industries and biomedical R&D. Little is known, however, on the effects of the vacuum on the yeast, and in particular, on the yeast lipidome that plays a central role in maintaining cell membrane and other vital (yeast) cell functions. The present study evaluated the adaptive responses of Saccharomyces cerevisiae to repeated vacuum fermentation by lipidomic analysis. We employed gas chromatography coupled to time-of-flight mass spectrometry (GC-TOF-MS) and liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI/MS(n)) to quantify a total of 13 intermediate sterols and 139 phospholipid species of yeast cells. Principal components analysis found that the PI (phosphatidylinositol) 26:0, PI 28:0, PE (phosphatidylethanolamine) 32:1, and PE 34:1 were potential biomarkers to distinguish the vacuum fermentation process. Quantitative analysis showed that vacuum fermentation increased the synthesis of PI and the PC (phosphatidylcholine) species with short saturated acyl chains. The synthesis of PC via CDP-choline and turnover of PC were enhanced, instead of formation via methylation of PE. Additionally, increased PI at the expense of PE and PG (phosphatidylglycerol) was associated with enhancement of ethanol productivity. Vacuum fermentation caused eburicol accumulation, suggesting that vacuum can activate the branch of the ergosterol biosynthesis pathway. Eburicol decrease and PI increase contributed to recovery of cellular activities with oxygenating treatment. Ethanol productivity was increased by sixfold in vacuum-treated cells. These observations may allow the development of future mechanistic approaches to optimization of yeast fermentation under vacuum for bioindustry and life science applications. In particular, our findings on changes in lipid molecular species and the ergosterol biosynthesis pathway elucidate the defense responses of yeast cell membranes during the repeated vacuum fermentation, which by extension, provided an important lead insight on how best to protect the cell membranes from the extreme long-term stress conditions.     

紫杉二烯人工酵母的代谢组学分析

为了更深入地从代谢角度研究萜类合成人工酵母的内在差异,以紫杉二烯人工酵母为例,利用代谢组学的方法对其发酵指数中期胞内代谢物的变化进行了测定。结果表明,与对照菌W303-1A相比,紫杉二烯的生产会对胞内糖酵解、三羧酸循环中间物及一些氨基酸的含量产生不同程度的影响,进而对其生长产生一定抑制作用。其中柠檬酸因紫杉二烯功能模块的引入下降明显,降幅达90%以上,因此可以作为后续功能酵母研究的标志性代谢物。紫杉二烯人工酵母细胞代谢组的研究可以为萜类化合物异源合成的优化提供更多的信息和帮助。     

7-脱氢胆甾醇合成功能模块与底盘细胞的适配性

利用合成生物技术生产7-脱氢胆甾醇的挑战性在于获得合成功能模块与底盘细胞的适配关系。从更换不同调控强度的启动子和不同改造的酵母底盘两方面,对二者的适配性进行研究,以增加7-脱氢胆甾醇产量:过表达酵母固醇合成途径中的内源基因tHMGR和ERG1,敲除非必需基因ERG6和ERG5以抑制酵母固醇向麦角固醇的转化,得到改造后的酵母底盘SyBE_000956;利用由强到弱依次为TDH3p、PGK1p和TDH1p的启动子,引入人源C-24还原酶基因DHCR24,构建3种强度的外源功能模块,并分别导入3种底盘中,得到9种人工合成细胞。结果表明,TDH3p调控的功能模块与底盘细胞SyBE_000956具备较好的适配性,实现7-脱氢胆甾醇产量的提高。为后续的适配性研究提供了理性设计的依据。     

Systems‐level quantification of division timing reveals a common genetic architecture controlling asynchrony and fate asymmetry

Coordination of cell division timing is crucial for proper cell fate specification and tissue growth. However, the differential regulation of cell division timing across or within cell types during metazoan development remains poorly understood. To elucidate the systems‐level genetic architecture coordinating division timing, we performed a high‐content screening for genes whose depletion produced a significant reduction in the a synchrony of d ivision between s ister cells (ADS) compared to that of wild‐type during Caenorhabditis elegans embryogenesis. We quantified division timing using 3D time‐lapse imaging followed by computer‐aided lineage analysis. A total of 822 genes were selected for perturbation based on their conservation and known roles in development. Surprisingly, we find that cell fate determinants are not only essential for establishing fate asymmetry, but also are imperative for setting the ADS regardless of cellular context, indicating a common genetic architecture used by both cellular processes. The fate determinants demonstrate either coupled or separate regulation between the two processes. The temporal coordination appears to facilitate cell migration during fate specification or tissue growth. Our quantitative dataset with cellular resolution provides a resource for future analyses of the genetic control of spatial and temporal coordination during metazoan development.     

Amplification loop cascade for increasing caspase activity induced by docetaxel

The hierarchy of events accompanying induction of apoptosis by the microtubule inhibitor docetaxel was investigated in HL-60 human leukemia cells. Treatment of HL-60 cells with docetaxel resulted in the production of reactive oxygen species (ROS), activation of caspase-3 (-like) protease, c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) activation, bcl-2 phosphorylation and apoptosis. Docetaxel elicited ROS production from NADPH oxidase as demonstrated by specific oxidase inhibitor diphenylene iodonium (DPI). ROS mediated the caspase-3 activation and apoptosis in HL-60 cells. The caspase inhibitor acetyl-Asp-Glu-Val-Asp-aldehyde (Ac-DEVD-CHO) effectively inhibited JNK/SAPK activation, bcl-2 phosphorylation and partially attenuated the ROS production induced by docetaxel. Docetaxel-induced bcl-2 phosphorylation was completely blocked by expression of dominant negative JNK or the JNK/SAPK inhibitor SP600125. Overexpression of bcl-2 partially prevented docetaxel-mediated ROS production and subsequent caspase-3 activation, thereby inhibiting apoptotic cell death. It is thus conferred that such sequent events as ROS production, caspase activation, JNK/SAPK activation, bcl-2 phosphorylation and the further generation of ROS should be parts of an amplification loop to increase caspase activity, thereby facilitating the apoptotic cell death process.     

南方红豆杉细胞培养合成紫杉醇诱导子浓度的优化

本文利用短期诱导实验考察了几种诱导子的最优诱导浓度,结果表明,在南方红豆杉细胞培养体系中分别加入１．０ｍｍｏｌ／Ｌ硝酸铈铵、０．０１ｍｍｏｌ／Ｌ硝酸银、０．１ｍｇ／Ｌ花生四烯酸、０．１ｍｇ／Ｌ水杨酸以及１０．０ｍｇ／Ｌ甲基苯莉酮酸最有利于紫杉醇产量的提高。     

Negative supercoils regulate meiotic crossover patterns in budding yeast

Interference exists ubiquitously in many biological processes. Crossover interference patterns meiotic crossovers, which are required for faithful chromosome segregation and evolutionary adaption. However, what the interference signal is and how it is generated and regulated is unknown. We show that yeast top2 alleles which cannot bind or cleave DNA accumulate a higher level of negative supercoils and show weaker interference. However, top2 alleles which cannot religate the cleaved DNA or release the religated DNA accumulate less negative supercoils and show stronger interference. Moreover, the level of negative supercoils is negatively correlated with crossover interference strength. Furthermore, negative supercoils preferentially enrich at crossover-associated Zip3 regions before the formation of meiotic DNA double-strand breaks, and regions with more negative supercoils tend to have more Zip3. Additionally, the strength of crossover interference and homeostasis change coordinately in mutants. These findings suggest that the accumulation and relief of negative supercoils pattern meiotic crossovers.