绿臭蛙皮中与神经降压肽有关的绿臭蛙降压肽的分离及其化学和生物学特征

本文利用Sep-Pak Cu和反相HPLC从我国产绿臭蛙皮的甲醇提取物中分得一新的神经降压肽类似物:绿臭蛙降压肽。其结构为Asp-Lys-Arg-Pro-Tyr-Ile-Leu-His-Glu。此结构与神经降压肽羧端部分结构相似。但比后者多出残基His-Glu。相应的合成品与天然肽在高效液相色谱、氨基酸分析和生物测定中均表现一致。此肽对大鼠产生降血压效应,但作用比神经降压肽弱。该肽对豚鼠回肠制品有很强的和可重复的收缩活性,这一点又与两栖动物皮肤中另一神经降压肽类似物——xenopsin的相应活性有别。     

我国产绿臭蛙的皮肤中一个新的速激肽——绿臭蛙激肽的分离和结构

本文利用Sep—Pak C_(13)和HPLC,从我国产绿臭蛙的皮肤甲醇提取物中分离到一个新的14肽——绿臭蛙激肽。此肽结构经分析定为:Asp—Asp—Ala—Ser—Asp—Arg—Ala—Lys—Lys—Phe—Tyr—Gly—Leu—Met—NH_2,且为化学合成所证明。此肽是两栖动物速激肽中最长的一个,其N-端氨基酸与速激肽类其它肽的相应部分有很大区别。此外,简要讨论了纯化过程中绿臭蛙激呔亚砜的形成及其色谱峰的分裂。     

洞庭湖滨湖丘岗地鼠类群落演替

作者于1992~1995年和2002~2004年,对洞庭湖滨湖丘岗地的鼠类群落结构和生物多样性变化进行了研究.共置鼠夹2 437夹夜,捕鼠7种,共417个个体.结果表明两个时间段捕获的鼠种数不同,分别为7种和5种,捕获率分别为(12.29±7.05)%和(3.05±1.44)%(t=4.26,df=21,p<0.001);两个时间段的优势鼠种不完全相同,东方田鼠和黑线姬鼠为1992~1995年的优势鼠种,社鼠和黑线姬鼠为2002~2005年的优势鼠种;两个时间段的物种多样性指数和优势度指数差异不显著,但均匀性指数差异显著(t=5.433,p<0.05).对两个时间段的鼠类群落相似性指数进行系统聚类分析,将所有年份的群落相似性指数聚类为2类,即1992~1994年聚为一类,2002~2004年聚为一类.结果表明洞庭湖滨湖丘岗地鼠类群落经过10年的演替,已经成为完全不同的群落.     

ISOLATION, CHEMICAL AND BIOLOGICAL CHARACTERIZATION OF MARGARATENSIN, A NEUROTENSIN-RELATED PEPTIDE FROM THE SKIN OF Rana margaratae

A new neurotensin (NT)-related peptide, margaratensin, was obtained by Sep-Pak C_(18) and RP-HPLC from methanol extracts of the skin of Chinese frog Rana margaratae. The structure of the peptide has been determined to be Asp-Lys-Arg-Pro-Tyr-lle-Leu-His-Glu, which is found to be homologous to the COOH-terminal sequence of NT, but has an extra His-Glu at the COOH-terminus. The synthetic preparation was shown to be indistinguishable from the native peptide during HPLC, amino acid analysis and bioassay. Margaratensin exhibited a hypotensive effect in the rat but the response was weaker than NT. The peptide could induce a potent and reproducible contractile activity on GPI which was different from xenopsin, another NT-related peptide from amphibian skin.     

ISOLATION AND STRUCTURE OF RANAMARGARIN,A NEW TACHYKININ FROM THE SKIN OF CHINESE FROG Rana margaratae

A new tetradecapeptide, ranamargarin, has been isolated by Sep-Pak C_(18) and HPLC from methanol extracts of the skin of the Chinese frogRana margaratae. The sequence of the peptide is: Asp-Asp-Ala-Ser-Asp-Arg-Ala-Lys-Lys-Phe-Tyr-Gly-Leu-Met-NH_2. This structure has been confirmed by synthesis. The peptide is the largest among the amphibian tachykinins and its N-terminal amino acids are quite different from those of the other tachykinins. The formation of the sulfoxide and peak-splitting of ranamargarin during purification procedures are briefly discussed.