爪蟾脊索在决定过程中和相邻细胞的关系

已经知道,对预定脊索的决定起重要作用的是位于它两侧的预定肌节。电子显微镜的观察指出,预定脊索和肌节细胞相互靠得很近,或者相隔一定距离,以突起相连形成腔隙。有被小窝和小泡在两类细胞的外缘常被观察到。最引人注意的是在肌节细胞近腔隙的部位或者附近,球状体的出现。它们大小不等,内含物主要是颗粒,有的松散分布,有的致密地充满整个球状体。这些颗粒的大小和电子染色与这时期胚胎细胞中的核糖体很相似。在预定脊索细胞中以及附近,未见上述结构,但是,观察到它们伸出突起包吞腔隙中物质的现象。讨论了这些球状体的出现与脊索决定之间可能存在的关系。     

利福霉素生产菌产生钝化RifSV物质的分离及性质研究

利福霉素ＳＶ（简称ＲｉｆＳＶ）生产菌──地中海拟无枝菌酸菌在生物合成ＲｉｆＳＶ过程中,产生一种能钝化自身产物（ＲｉｆＳＶ）的物质．实验证实,该物质是由谷氨酸、天冬氨酸、赖氨酸及缬氨酸等１４种常见氨基酸组成的蛋白质．分子量（ＭＷ）约２．５×１０４Ｄ,等电点（ＰＩ）为５．７—６．１．在１００℃下加热１０ｍｉｎ,其活性丧失．作用于ＲｉｆＳＶ的最适ｐＨ值范围为７．４—８．６,最适温度为２９℃,初步证实该物质是一种酶（暂称利福霉素钝化酶）     

大兴安岭林区针叶林的生长方程及火灾林木死亡率

本文用随机模拟的方法建立了北方针叶林的生长方程及其受到火灾侵害后的林木死亡率,定量地研究了火灾对这种林分变动的影响．     

大瓶螺碱性磷酸酶的分离纯化及部分性质研究

大瓶螺碱性磷酸酶的分离纯化及部分性质研究李清漪,曾和期（西南师范大学生物系,重庆６３０７１５）碱性磷酸酶（ＥＣ３．１．３．１,简称ＡＫＰ）是广泛存在于动物组织中的水解酶。对软体动物中ＡＫＰ的研究仅有少数报道［１,２］,对属于单壳贝类的水生食用螺──大...     

Effects of substrate limitation on product distribution and H2/CO2 ratio inKlebsiella pneumoniae during anaerobic fermentation of glycerol

Product formation during anaerobic degradation of glycerol byKlebsiella pneumoniae DSM 2026, under glycerol limitation and glycerol excess in continugius cultures, has been investigated. Major and minor products and by-products as well as gaseous products were measured. The results indicated a positive correlation between specific glycerol uptake and most product formation rates under glycerol limitation. The production of 1,3-propanediol, lactate, formate, acetate, succinate and the by-products of anaerobic glycerol degradation byK. pneumoniae, acetoin and 2,3-butanediol, was favoured by glycerol excess, while hydrogen generation and ethanol formation were best under glycerol limitation. It was also found that under glycerol limitation the rate of hydrogen evolution was generally higher than the CO₂ production rate while under excess glycerol the reverse was true. Hence, on the basis of the ratio of the specific rates of evolution of H₂ and CO₂ (q _{H 2}/q _{CO 2}), it is possible to infer the existence of glycerol limitation. On the basis of the carbon and available electron balances, which are independent of metabolic pathways, the data are consistent. The NADH₂ balance, which took into consideration the pathways of product formation, was also tested to check the validity of the assumed pathways and to check critically the consistency of the data. Good balances were also obtained.[     

高原鼠兔季节性繁殖中的神经内分泌调控Ⅱ．不同光制对生殖恢复期的影响

本项研究将野外捕获的成年雄性高原鼠兔（Ｏｃｈｏｔｏｎａｃｕｒｚｏｎｉａｅ）分３组进行不同光制的饲养,以检验光周期对其神经内分泌─—生殖轴功能的影响：（１）长光照组睾丸及附属性腺的重量和血浆睾酮水平均明显高于自然光组（ｐ＜０．０５）和短光照组（ｐ＜０．０１）。（２）长光照组的松果腺重量（１．５±０．１毫克,ｎ＝１５）和褪黑激素含量（８９．７±５．８微微克／松果腺）,均显著低于其它两组。（３）自然光组和短光照组性腺的显著萌发表明,在高原鼠兔季节性繁殖的年周期中,其神经内分泌─—生殖轴对春分前短光照的抑制作用具有不应期。