A nerve growth factor from the venom of Chinese cobra (Naja naja atra) and its effects on male reproductive system in rats

A nerve growth factor (NGF) was isolated from the venom of Chinese cobra (Naja naja ntr a) by ion exchange chromatography, gel filtration and fast protein liquid chromatography (FPLC). The N-terminal sequence of 22 amino acid residues was identical with other NGFs previously purified from the venom of the same genus. The NGF monomer molecular weight was estimated to be 13 500 by reducing SDS-PAGE and the isoelectric point was determined to be 7.2 by isoelectric focusing electrophoresis. NGF improved the epididymal sperm motility of male rats and increased the pregnancy rate and fetus number of mated female rats. The serum levels of luteinizing hormone (LH) and follicle stimulating hormone (FSH) of male rats administrated NGF + gossypol was lower than that of male rats administrated gossypol. Histological sections of testes and epididymides showed that NGF reduced the destructive effects of gossypol on rat testes. (C) 1999 Elsevier Science Inc. All rights reserved.

生物钟基因period的分子生物学

国家自然科学基金;中国科学院基金

period基因的Thr-Gly区段在果蝇和部分双翅目昆虫中的分子进化特征

以亲缘关系极近的近缘种类群、中等距离的远缘种类群为对象，分析生物钟基因period基因的Thr-Gly区段的分子进化特征，发现Thr-Gly区段在果蝇和部分双翅目昆虫中未曾经历性选择和其他定向的正选择。Thr-Gly区段在果蝇nasuta亚群中的分子进化速率为10.4*10~-9同义替换/位点/年。

Drosophila auraria复合种Period基因Thr-Gly区段的初步研究

测定了金色果蝇复合种5个姐妹种和D. rufa的period (per)基因的Thr-Gly区段序列。该区段序列分析表明:DNA序列的碱基组成拥有果蝇其他基因的共同特点;颠换数多于转换数,两两物种间的颠换率与转换率的总比值为2-5,密码子第3位的颠换与转换的比值为2.5-5;同义替换/异义替换(Ks/Ka)值远大于10,且有的物种间根本不存在非同义突变,低的Ka值说明该复合种的per基因Thr-Gly区段在进化过程中可能承受着较强的选择压力。运用所得的核苷酸序列构建Drosophila auraria复合种的系统发育树,为澄清该类群的系统演化关系提供了新的线索。