Chromosomal localization of a unique gene by non-autoradiographic in situ hybridization

During the past few years, several methods have been developed for the detection of specific nucleic acid sequences by in situ hybridization using non-radioactive labels such as fluorochromes, cytochemically detectable enzymes and electron-dense markers. These methods are preferable to autoradiography in terms of speed of performance and topological resolution. Their limited sensitivity, however, has so far restricted their use to the detection of repeated sequences. Here we report single gene detection with a procedure using 2-acetylaminofluorene (AAF)-modified probes, immunoperoxidase cytochemistry and reflection-contrast microscopy. We confirmed the autoradiographic data on the localization of the human thyroglobulin (Tg) gene to the distal end of the long arm of chromosome 8. A mixture of cosmid cHT2-derived subclones of the 3' part of the Tg gene, 22.3 kilobase pairs (kbp) in total, was used as a hybridization probe. This procedure can be used to map other unique sequences, if genomic clones are available from which clones with an appropriate amount of inserts can be isolated.     

In vitro protein synthesis and α amylase activity in F cells from hepatopancreas ofPalaemon serratus (Crustacea; Decapoda)

In crustaceans, all the steps in the assimilation of food take place in the hepatopancreas. To facilitate the study of this organ, a method for the dissociation of cell types was developed. The hepatopancreas of the prawnPalaemon serratus was mechanically dissociated and the cells separated by Percoll density-gradient centrifugation. The E and R cells had similar densities of around 1.05 g/ml. The F cells were separated into two distinct fractions with densities of 1.075 and 1.082 g/ml. The B cells sedimented at a density of 1.12 g/ml. The ratio between the two populations of F cells was found to vary during the intermolt cycle while B cells disappeared after the molt. When the density gradient fractions were incubated with³H-leucine, incorporation was highest in the F cell fractions. Measurements of -amylase activity, indicated that the two populations of F cells may be derived from the same cell type.     

Regulation of cellulose synthesis in Acetobacter xylinum by cyclic diguanylic acid

Cellulose is the most abundant renewable carbon resource on earth and is an indispensable raw material for the wood, paper, and textile industries. A model system to study the mechanism of cellulose biogenesis is the bacterium Acetobacter xylinum which produces pure cellulose as an extracellular product. It was from this organism that in vitro preparations which possessed high levels of cellulose synthase activity were first obtained in both membranous and soluble forms. We recently demonstrated that this activity is subject to a complex multi-component regulatory system, in which the synthase is directly affected by an unusual cyclic nucleotide activator enzymatically formed from GTP, and indirectly by a Ca (2+) -sensitive phosphodiesterase which degrades the activator. The cellulose synthase activator (CSA) has now been identified as bis-(3' 5')-cyclic diguanylic acid (5'G3'p5'G3'p) on the basis of mass spectroscopic data, nuclear magnetic resonance analysis and comparison with chemically synthesized material. We also report here on intermediary steps in the synthesis and degradation of this novel circular dinucleotide, which have been integrated into a model for the regulation of cellulose synthesis.     

Transplantation of human cortex with Alzheimer's disease into rat occipital cortex; a model for the study of Alzheimer disease

Summary Senile dementia of the Alzheimer type (SDAT) is a major problem in the human senescent population. As this pathology cannot be reproduced in animals, research into its development is greatly impeded. The technique of implantation of the nervous tissue has been utilized in order to establish an animal model and to test the possible existence of a transmissible agent. When human temporal cortex with Alzheimer's disease is implanted in the occipital cortex of 7-week-old rats, human cerebral tissue containing abundant tangles induces in the receiver cortex a reactive fibrous gliosis. In the processes of the astrocytes, twisted filaments are evident among bundles of normal filaments. These alterations could be induced by the metabolising of abnormal filament subunits or by some infectious agent introduced by the implant.This study is supported by grant No. 2.4517.82 of Fonds de la Recherche Fondamentale Collective of Belgium.     

上升有序加权欧氏平均算子及其在决策中的应用

提出了一种上升有序加权欧氏平均 (AOWEA)算子 ,详细研究了它的一些优良性质 ,如 :单调性、置换不变性等 .给出了一种基于AOWEA算子的多属性决策方法 .最后通过实例说明了该方法的可行性和有效性 .     

卡诺图法化简异或逻辑函数

探讨了卡诺图化简异或逻辑函数的原理，提出了化简异或逻辑函数的新方法。     

变质产品供应链中多品种的订购策略研究

针对核心企业为订货商的变质产品供应链,建立了多品种的库存模型,分析了基于三种不同订购策略的总成本函数的性质,提出了多种变质产品的近似最优订购策略.最后,通过算例对理论结果加以说明.     

城市化进程中上海植被的多样性、空间格局和动态响应(Ⅰ):上海佘山地区残存自然植被种子植物区系及其50年的动态变化特征

通过对上海余山地区残存自然植被的区系分析,研究了城市化与片断化过程中自然植物种类的变化特征.利用样线法对十座山体进行调查,共记录野生种子植物85科235属350种,地理成分分布类型上共划分为13个分布区类型和10个变型.研究发现:佘山地区山体物种数与面积之间存在显著相关;作为天目山的余脉,佘山地区植物区系与天目山植物区系存在有极强的近缘关系;相比于1950年代的植物名录,佘山地区有178种自然种子植物未被发现,以多年生草本为主.     

基于公交视角的兰州市城市交通发展策略

从城市路网结构、机动车保有量、跨河交通以及市政工程等方面对交通发展的约束进行了讨论.在此基础上,进一步从线路长度、非直线系数、线网密度、首末站点设置等方面进行了系统分析,认为兰州市公交主要存在公交线路普遍偏长、线路非直线系数过大、线网密度差异大、首末站设置不均衡等问题.据此提出了优化路网结构、发展大容量公共交通、合理规划站点、积极开发水上交通、不断提升管理水平等措施,以期对兰州城市交通的持续健康协调发展和国内其他带状河谷城市发展交通提供决策参考.     

弹性球体在冲击载荷下的应力波传播

给出了弹性球体在冲击载荷下应力波传播的解析解。该解法是利用特征函数展开法，将动力学的一般解分解为满足非齐次边界条件的准静态解和仅满足齐次边界条件的自由振动解，其中准静态解满足欧拉方程，而自由振动解满足贝塞尔(Bessel)方程。利用分离变量法，贝塞尔(Bessel)方程的解是一个由球贝塞尔函数构成的级数形式解，然后将此解和准静态解叠加，可得弹性动力学问题的解。与特征线法，积分变换法，广义射线法相比具有物理意义更加明确，数学解法更加简明的优点，同时这一解法可以推广到任意载荷下，各向同性弹性动力学中的一般球对称问题。