Growth ofNostoc muscorum mutants in the presence of diuron (DCMU) and L-methionine-DL-sulfoximine

Summary Diuron (DCMU) is inhibitory to the photoautotrophic and photoheterotrophic growth of the N₂-fixing blue-green algaNostoc muscorum at concentrations of 1.0×10^–5 M and 2.0×10^–5 M, respectively. A mutant of this organism resistant to 5.0×10^–5 M DCMU under its photoheterotrophic growth conditions, with the ability to utilize DCMU as a carbon and nitrogen source for growth, and complete inability to grow photoautotrophically has been isolated. With the apparent defect in its photosynthetic ability, it is suggested that theDCMU ^r mutant lacks the step inhibited by 1.0×10^–5 M DCMU, and metabolizes DCMU by an existing enzyme system in the absence of such inhibition. That this enzyme may be glutamine synthetase (GS) is explained with the help of a L-methionine-DL-sulfoximine (MSO)-resistant mutant ofN. muscorum which is able to grow faster with 2.0×10^–5 DCMU and is known to contain an altered GS.Thanks are due to the Council of Scientific and Industrial Research, CSIR Complex, Govt. of India, New Delhi-110012, for appointing the author to the Scientists' Pool for undertaking researches on the physiological and genetic controls of nitrogen metabolism in blue-green algae, a part of which is presented in this literature.     

大熊猫的繁殖生态学研究

大熊猫在饲养状况下,多数雄性不具交配能力,雌性能受孕产仔的也少。通过在野外进行繁殖生态学的研究,揭示了产生这一现象的原因,为抢救这一濒危物种和保护管理提供了理论依据。     

经济增长与政治合法性的关系探析

20世纪90年代中期以来，一方面中国经济高速增长，另一方面却又面临政治合法性危机。究其原因，在于经济增长模式不同，单纯的经济增长并没有带来政治的必然合法性。政治合法性要求公正、持续、协调的经济增长。随着社会的变迁，政治合法性基础也应不断变化。在新形势下，政治合法性建设应在原有的政绩合法性基础上，构建法理型的合法性。     

Fourier analysis of vertebral shape change due to growth and selection for large and small body size

Summary Fourier analysis of videodigitised outlines of mouse vertebrae from two stocks, a pseudo-longitudinal series of mice aged 25–60 days and one selected for large or small body size over many generations shows that the shape changes due to normal growth are not similar to those produced by selection for body size.     

Cadmium-induced changes in avian renal morphology

Summary The effects of i.m. administered cadmium on growth rate and nephromorphology were studied in young pullets. The growth rate of pullets treated with 0.6 mg Cd²⁺/kg at 48-h intervals was severely retarded, reaching only 50% of normal growth by 21 days. Such a decrease in growth rate was prevented when cadmium was given with either ferric or magnesium EDTA chelate. Electron micrographs of kidney tissue from cadmium intoxicated birds revealed massive intracellular disorganisation of proximal tubular cells, showing increased vacuolation and dilated endoplasmic reticulum. Mitochondria were few and swollen with reduced cristae. Some disorganisation was noted in the group treated with MgEDTA in conjunction with cadmium, with normal morphology observed in the group treated FeEDTA plus cadmium.In general, glomerular morphology of intoxicated pullets appeared normal, except that a 25% increase in thickness of the glomerular basement membrane was evident. No such membrane thickening was observed in any of the chelate treated groups.These findings indicate that both chelates can provide certain levels of protection, in terms of growth rate and morphology, from cadmium intoxication. The possible mechanisms by which chelates offer protection have been discussed, but many questions remain unanswered.     

小麦生育期亚性状的配合力研究

本研究以６个小麦品种（系）为亲本，按Ｇｒｉｆｆｉｎｇ方法２进行完全双列杂交，对小麦生育期亚性状（抽穗期、开花期、成熟期、籽粒发育期、旗叶功能期）进行了配合力分析。结果表明：５个性状的一般配合力均方和特殊配合力均方均达到极显著，并且一般配合力的作用大于特殊配合力的作用。本文依据一般配合力效应、特殊配合力效应和特殊配合力方差，对各供试亲本在育种中的利用价值进行了评价。     

Early Stage Software Reliability Estimation with Stochastic Reward Nets

IntroductionMost software reliability growth models (SRGM) arefailure-based growth models .The“black box”approach of theSRGMrequires alarge number of failures , while these failurescannot be available until the late stages in the softwaredevelopment process .It is i mportant to be able to esti mate thereliability growth at the early stage,and this can demonstratethat the systemdesignis ontrackfor meeting requirements ,sothat appropriate planning regarding the release ti me,price andadditi…     

二维非稳态晶体生长问题的扰动分析

在晶体生长过程中,由于溶质原子的吸附作用、电磁搅拌等诸多因素的干扰,会在固液平直界面产生扰动,进而影响界面形态.研究了具有凝固平直界面的二维非稳态晶体生长过程,通过稳定流场下的温度场扰动分析,利用摄动方法将问题展开,求出零阶及一阶渐近解并进行讨论,给出解的稳定性条件.结果表明,在扰动条件下,稳定流场中的温度变化沿晶体生长方向呈指数衰减,可为晶体生长的理论研究及实验工作提供一些理论依据.     

猪生长激素基因启动子区的序列变异研究

采用聚合酶链式反应(PCR)及PCR产物直接序列分析方法，对猪生长激素基因(pGH)5’-侧翼区(启动子区)序列的遗传变异进行研究，共分析了6头临高猪、3头玉山黑猪和5头蓝塘猪．结果表明：在猪生长激素基因启动区，共有10处碱基替换，它们分别位于：72位C→T，238位G→T，343位A→G，274位A→G，721位G→C。722位T→C，723位G→C，728位C→T，784位G→C，787位G→T．2处碱基插入，依次是180位插入碱基G。416位插入碱基C．新发现了3处碱基置换，分别是721位G→C，722位T→C，723位G→C和1处碱基插入，416位插入碱基C．