从福尔马林保存的牙鲆中克隆的18S rDNA进行系统发育分析的可靠性

从福尔马林保存的牙鲆和活体牙鲆肌肉组织中，利用基因拼接的方法首次克隆到1205bp和1295bp的长片段序列。福尔马林保存标本与活体标本DNA序列的同源率为82％；和活体标本的18S rDNA序列相比，标本DNA的碱基缺失率为7％，碱基替换比例为11％。利用福尔马林标本的18S rDNA同源性高的区域进行系统发育分析，表明其结果是可信的。

On the rationality of phylogenetic analyses of 18S rDNA cloned from formalin-fixed Paralichthys olivaceus

Because some species of fishes have been becoming more and more difficult to be collected, many phylogenetic researchers have no other choice but adopt formalin-fixed specimens. There are many reports on molecular phylogenetic analyses based on DNA sequences from formalin-fixed specimens, but seldom researches have discussed the reliability about the DNA sequences from formalin-fixed specimens in applying phylogenetic analysis. Here the partial sequences, 1205bp and 1295bp 18S rDNA we reported, were first cloned form muscle of formalin-fixed and live Paralichthys olivaceus by using gene overlap strategy. Compared with live specimen, 80% bases of 18S rDNA sequence are identical, 7% are deleted, and 11% are replaced in formalin-fixed specimen. The DNA sequences from formalin-fixed and live specimens were used simultaneously in phylogenetic analysis based on high homology area. We think it is reliable in high-class molecular phylogenetic analysis.