星虫胶原蛋白的纯化及其性质的初步分析

本实验研究了水生环节动物星虫胶原蛋白的提取及纯化方法.SDS-PAGE电泳分析结果显示,所提取的胶原蛋白纯度较高.通过粘度测定分析星虫胶原蛋白的变性温度约35℃.酶解性质的研究表明,纯化的星虫胶原蛋白可被胰蛋白酶、胃蛋白酶和蛋白酶K水解.     

Sipunculus nudus Linnaeus, 1766 (Sipuncula): cosmopolitan or a group of pseudo‐cryptic species? An integrated molecular and morphological approach

Sipunculan taxonomy relies on a limited set of external morphological and internal anatomical characters. In addition, this marine group is characterized by an unusual large number of putatively cosmopolitan species. However, this ‘cosmopolitan’ status could be an artifact of their conserved morphology and the small number of unambiguous taxonomic characters available for delimiting species. Species delimitation can therefore be aided by molecular techniques. We investigated the case of the widespread and common species Sipunculus nudus Linnaeus, 1766 to determine its systematic validity. We analysed the morphology of multiple specimens of S. nudus collected from 11 localities around the world and undertook phylogenetic analyses using molecular sequence data from four genes (28S rRNA, 16S rRNA, histone H3 and cytochrome c oxidase subunit I). High levels of genetic differentiation are present between distantly related populations of the putative species S. nudus. Five distinct lineages were identified by phylogenetic analyses, three of which – the best‐represented populations – can be distinguished morphologically. Our phylogenetic and morphological analyses thus do not favor the cosmopolitan status of S. nudus, suggesting instead that it constitutes a complex of morphologically similar but distinguishable species.