泉水唇鱼的核型和带型研究

该文用上皮细胞培养方法对金沙江水系的泉水唇鱼(Semilabeo p rochilus)染色体进行了研究. 其二倍体数2n=50, 核型组成为16m+20sm+14st, NF=86. 阳性C-带位置有几种类型:(1)着丝粒区; (2)短臂异染色质化; (3)插入异染色质带. Ag-NOR、有7条, 出现在Nos. 10-13染色体短臂. 根据以上所述的特征, 推测泉水唇鱼可能是较为特化的种类。

中国家鸡的起源探讨

测定了6个家鸡品种30个个体的线粒体D-环区539bp的碱基序列,并与GenBank中的红原鸡、灰原鸡、绿原鸡、黑尾原鸡及鹌鹑的相应序列作比较分析,构建了分子系统树。结果表明,原鸡属4个种间差异较大,其中家鸡与泰国及邻近地区红原鸡关系最近,与印尼红原鸡、黑尾原鸡、灰原鸡、绿原鸡及鹌鹑的关系依次变远。提示中国家鸡可能起源于泰国及邻近地区的红原鸡。结果还显示,该地区红原鸡的两个亚种(G.g.gallus和G.g.spadiceus)间的遗传分化程度显著低于家鸡亚种内的分化程度,这两个亚种似乎可以归为同一亚种。

Adaptive evolution of a duplicated pancreatic ribonuclease gene in a leaf-eating monkey

Although the complete genome sequences of over 50 representative species have revealed the many duplicated genes in all three domains of life(1-4), the roles of gene duplication in organismal adaptation and biodiversity are poorly understood. In addition,

Episodic evolution of prolactin receptor gene in mammals: coevolution with its ligand

Divergence of proteins in signaling pathways requires ligand and receptor coevolution to maintain or improve binding affinity and/or specificity. In this paper we show a clear case of coevolution between the prolactin (PRL) gene and its receptor (prolactin receptor, PRLR) in mammals. First we observed episodic evolution of the extracellular and intracellular domains of the PRLR, which is closely consistent with that seen in PRL. Correlated evolution was demonstrated both between PRL and its receptor and between the two domains of the PRLR using Pearson's correlation coefficient. On comparing the ratio of the nonsynonymous substitution rate to synonymous substitution rate (omega=d(N)/d(S)) for each branch of the star phylogeny of mammalian PRLRs, separately for the extracellular domain (ECD) and the transmembrane domain/intracellular domain (TMD/ICD), we observed a lower omega ratio for ECD than TMD/ICD along those branches leading to pig, dog and rabbit but a higher ratio for ECD than TMD/ICD on the branches leading to primates, rodents and ruminants, on which bursts of rapid evolution were observed. These observations can be best explained by coevolution between PRL and its receptor and between the two domains of the PRLR.

人类基因同义密码子偏好的特征以及与基因GC含量的关系

对人类的728个基因，按其编码区中GC的含量分成四组（从GC < 0.43到GC > 0.58），分别考察了这四组样本对同义密码子偏好的特征，发现在全部样本中都呈现NTG（N代表四种碱其中的任一种）特爱偏爱和NCG尽量避免的特征。基因环境中GC含量与C3／G3含量（密码子第三位C和G的含量）的相关分析，以及四组本对密码子的偏好都支持以C线的密码子在编码中有特殊的优势，这种优势有利于保证翻译的准确性。还考察了各种氨基酸含量随编码区GC含量不同而变化的趋势。

A molecular model of braid-like DNA structure

The three-dimensional molecular models of DNA triple helices and triple-stranded brain-like structure were built up by molecular architecture, and their structural features and energy decomposition were examined. The results showed: (i) The base triplet is the element forming braid-like and triple helix DNA; (ii) Under specified conditions, DNA could form the triplet-stranded braid-like structure; (iii) DNA stability of the braid-like structure is less than that of the triple helix structure. (C) 1995 Academic Press Limited.

The features of synonymous codon bias and GC-content relationship in human genes

728 human genes were divided to four groups according to the GC contents of their coding sequences (from GC<0.43 to GC>0.58). Examination of synonymous-codon bias in the 4 groups show that NTG (N represents any base of T, A, C, G) is most favored and NCG

动物种质细胞的超低温冷冻保存

从目前的研究情况来看,动物种质细胞超低温保存的常用方法有程序降温法和玻璃化法。防冻剂主要分为渗透性和非渗透性。而冷冻损伤则指由于慢速降温过程中电解质深浓度变化引起的渗透性损伤和快速降温过程中形成的冰晶损伤。就不同种质细胞的冷冻保存在这些方面的研究进展做一综述,以供有关研究者参考。

云南新平哀牢山秋季夜间网捕鸟类的影响因素

2007-09-05-2007-11-05和2008-09-03-2008-11-07期间,在云南省新平县哀牢山金山丫口(23°57′N,101°30′E)对影响秋季夜间网捕鸟类组成因素进行了调查.主要利用温湿度表和定性观察对各因素进行判断.其研究结果表明,地理特点是影响夜间刚捕鸟类种类的主要因素:气象条件是影响夜间网捕鸟类种类和数量的重要因素.气象条件中的风向、风力、雾以及月相周期对夜间网捕鸟类数量和种类的影响极其显著(P<0.01).风向的影响比风力大,其中,在西南风大雾新月或者存西南风大雾残月期间,夜间网捕鸟类数量和种类最多:光也是夜间网捕鸟类的必要条件.然而,温湿度对夜间网捕鸟类数量和种类影响不显著.

欧洲鳗鲡淋巴细胞转化试验条件的建立

通过对培养时间、培养温度、刀豆蛋白A(ConA)质量浓度和鳗鲡血清质量分数4个参数的测定,确定欧洲鳗鲡(Anguilla anguilla)外周血淋巴细胞转化试验四甲基偶氮唑(MTT)法的实验条件。结果表明,在培养时间为42-90 h,培养温度分别为15.0℃、20.0℃、25.0℃和30.0℃时,细胞培养液中ConA质量浓度分别为0、10μg/mL、20μg/mL和30μg/mL,鳗鲡血清质量分数分别为0、5%、10%和15%时,淋巴细胞于20.0℃、含10μg/mL ConA,10%鳗鲡血清的RPMI

长江江豚和瓶鼻海豚的血清转铁蛋白

农业部淡水鱼类种质资源与生物技术重点开放实验室开放课题资助项目(LFB20040513)