巢湖沉积植硅体组合及中全新世以来的环境演变

尽管以前对眼虫进行过大量的形态发育研究和基于核糖体RNA基因的系统发育分析,但对于株系之间的关系仍然知之甚少．因其形态特征有限并且易变,很难鉴定眼虫的相似种和同种内不同的株．作者利用微卫星DNA指纹图谱,在七株眼虫中扩增了七个微卫星DNA位点,成功扩增的六个微卫星引物都得到了四到八个条带．从微卫星DNA指纹图谱计算得到的相似性系数范围从0．000到0．957．根据相似性系数得到的树状结构,七株眼虫在距离为0．9346处分为三支:E．mutabilis,E．intermedia和E．gracilis．其中,五株E．gracilis分为两组:来自日本的和美国的．不同地区的株得到不同的基因型,并初步分析了它们之间的关系．研究表明七株眼虫根据微卫星DNA指纹图谱被明显区分开．微卫星DNA指纹图谱具有很高的分辨率,是鉴定和区分原生动物相似种和同种内不同株的一种有用的新方法．

Phytolith in the sediment of the Lake Chaohu since Middle Holocene and its paleoenvironmental implications

The genetic relationships among Euglena strains remain poorly understood, despite a rich history of morphological examination and an extensive phylogenetic analysis of the ribosomal RNA genes. It is difficult to identify related species of the genus Euglena and to separate different strains of the same species because the morphological characters are variable and limited. We address this question using microsatellite DNA fingerprinting. Seven microsatellite loci were amplified from 7 Euglena strains. A total of 4-8 bands were successfully amplified for each of 6 microsatellite primer pairs. Microsatellite DNA fingerprinting and similarity values ranging from 0.000 to 0.957 among the seven strains were obtained,which were used to construct a similarity tree among them. According to the tree, at the linkage distance of 0.9346 seven strains were separated into three clusters:E. mutabilis, E. intermedia and E. gracilis consisting of Japanese and USA groups. Further,in the cluster E. gracilis, different genotypes were recognized for the strains from different geographical origins. The relationships among species and strains were analyzed preliminarily. We demonstrates that the seven strains of Euglena can be clearly separated by their microsatellite DNA fingerprinting patterns. The microsatellite DNA fingerprinting has a high resolution and is a new useful method to identify and separate similar species and intraspecific strains in free-living protozoa.