细胞分裂素生物合成基因在调节一组烟草病理相关蛋白基因表达中的作用

对一组病理相关蛋白基因在烟草 ( N icotiana tabacum cv. Wisconsin 38)中的表达情况进行了研究 ,包括 :碱性几丁质酶、β- 1 ,3-葡萄糖苷酶、渗透蛋白及伸展蛋白。RNA杂交实验表明在正常烟草植株中上述 4个基因具有发育和器官专一性的表达。在含有细胞分裂素生物合成基因的转基因烟草丛生芽中 ,这 4个基因的表达受过量合成的内源细胞分裂素和载体效应的共同调节 ,细胞分裂素降低这些基因的表达 ,而载体效应则促进它们的表达。热激处理也明显降低这 4种基因的表达水平。上述结果表明这些病理相关蛋白基因具有复杂的调控系统     

荧光假单胞菌抗噬菌体菌株的选育

本实验从荧光假单胞菌（Ｐｓｅｕｄｏｍｏｎａｓｆｌｕｏｒｅｓｃｅｎｓ）ＡＳ—３菌株的不正常发酵液中分离到一种噬菌体,将其命名为ＰＦＡＳ。ＡＳ—３菌株能利用葡萄糖发酵产生Ｄ－异维生素Ｃ的前体物质２－酮基－Ｄ－葡萄糖酸。电镜观察表明ＰＦＡＳ噬菌体呈蝌蚪形,具有直径为６６ｎｍ的六角形头部及长１１７ｎｍ的尾部。通过紫外线诱变及自然选育两种途径,配合简便有效的初筛方法,经多次分离、纯化、复筛最终在摇并发酵试验中获得６株产量稳定地高于对照敏感菌的抗噬菌体菌株,可望用于生产。     

中国沿海代表性河口地区鳗苗群体形态特征的比较研究

本文报道了１９９２—１９９４年连续３年采自海南至辽宁（包括台湾）沿海７个代表性河口地区鳗苗群体的主要形态特征比较研究结果。４项计数性状和３项度量性状,差异系数分析结果未达到亚种差异水平;判别函数显示,大多数群体间存在显著差异,这种差异应源于遗传变异。各年差异变化无规律,可能与鳗苗漂游分布的随机性有关。     

云南高黎贡山蚤类的生态区系

本文报道了１９８５年以来对我甸横断山南端高黎贡山东、西坡蚤类生态区系的调查及研究结果。共发现蚤类５科２３属４７种（亚种）。文中对该山脉蚤类在不同森林植物带的群落结构、种的多样性及均匀度,各种蚤的栖境幅度、宿主多样性进行了陈述和比较,并对蚤类的区系特征、特有种的区系划分等问题进行了讨论。     

Plant cells contain a novel member of the retinoblastoma family of growth regulatory proteins.

The product of the retinoblastoma susceptibility gene (Rb) controls the passage of mammalian cells through G1 phase. Animal virus oncoproteins interact with the Rb protein via an LXCXE motif and disrupt Rb-E2F complexes, driving cells into S-phase. Recently, we found that the RepA protein of a plant geminivirus contains an LXCXE motif that is essential for its function, a finding that predicts the existence of Rb-related proteins in plant cells. Here we report the isolation of a maize cDNA clone encoding a protein (ZmRb1) which, based on structural and functional studies, is closely related to the mammalian Rb family of growth regulatory proteins. ZmRb1 shows a high degree of amino acid conservation when compared with animal Rb members, particularly in the A/B 'pocket' domain, but ZmRb1 has a shorter N-terminal domain. ZmRb1 forms stable complexes with plant LXCXE-containing proteins, e.g. geminivirus RepA protein. Geminivirus DNA replication is reduced in plant cells transfected with plasmids encoding either ZmRb1 or human p130, a member of the Rb family. This suggests that ZmRb1 controls the G1/S transit in plant cells and is consistent with the fact that geminiviruses need an S-phase environment for DNA replication, as animal DNA tumor viruses do. Our results allow the extension of the Rb family of tumor suppressor proteins to plants and have implications on animal and plant strategies for cell growth control.     

Energy metabolism and ATP balance in animal cell cultivation using a stoichiometrically based reaction network

A metabolic reaction network is developed for the estimation of the stoichiometric production of adenosine triphosphate (ATP) in animal cell culture. By using the material balance data from fed-batch and batch cultures of hybridoma cells, the stoichiometric ATP productions are determined with estimated effective P/O ratios of 2 for NADH and 1.2 for FADH(2). A significant percentage of the ATP requirement (16-41%) in hybridoma cells is generated directly from free energy release without the participation of oxygen. The oxidative phosphorylation of NADH accounts for about 60% of the total ATP production in the fed-batch cultures and about 47% in the batch culture. The oxidative phosphorylation of FADH(2) accounts for less then 20% of the total ATP production in all cases.A fractional model is devised to analyze the contribution of each nutrient to the ATP production. Results show that a majority of the ATP is produced from glucose metabolism (60-76%). Less than 30% of the ATP is derived from glutamine, and less than 11% is derived from other essential amino acids. The analysis also shows that the glycolytic pathway generates more ATP in the batch (41%) than in the fed-batch (<27%) cultures. The TCA cycle provides 51-68% of the total ATP production. The calculated stoichiometric oxygen consumption differs among the batch and fed-batch cultures, depending on the glucose concentration. This result suggests that the relationship between the oxygen uptake rate (OUR) and cell growth may change with the culture conditions. However, the calculated respiratory quotient (RQ) is relatively constant in all cases.A linear relationship is obtained between the specific ATP production rate and the specific cell growth rate. The maximum ATP yield and the maintenance ATP requirement are determined based on this linear relationship. The biosynthetic ATP demand estimated from the dry cell weight and cell composition is significantly lower than that calculated from the maximum ATP yield, indicating that the non-growth-associated ATP demand may contain other factors than what is considered in the estimation of the biosynthetic ATP demand. (c) 1996 John Wiley & Sons, Inc.     

乙肝病毒PreSl片段与乙肝表面抗原羧端的融合表达

我们利用聚合酶链反应法（ＰＣＲ）得到了编码乙肝病毒肝细胞受体结合位点ＰｒｅＳｌ（２１￣４７）的基因片段,并将它分别融合到Ｓ基因中相应于第１７５,１８８和２２３位氨基酸残基处。所得到的融合基因插入痘苗病毒表达载体ｐＧＪＰ－５后,在哺乳动物细胞ＣＶ－１中进行了暂时表达,对融合蛋白的表达、分泌和抗原性的研究表明,３种融合基因均能表达具有Ｓ和ＰｒｅＳｌ双重抗原性的融合蛋白,但融合位点对表达水平和分泌性质有