裂殖壶菌OUC88 及10 个派生菌株18S rDNA 基因克隆和分析

用PCR方法从裂殖壶菌Schizochytrium limacinum OUC88及以其为出发菌株经紫外诱变筛选的10个菌株中扩增出18S rDNA基因序列(1751bp到1758bp)进行序列测定,以上序列已登录GenBank(HM042904-HM042914)并与已登录的裂殖壶菌属5条18S rDNA序列比对分析。结果表明,S.limacinum OUC88以及10个派生菌株间18S rDNA的遗传距离是0.000~0.013,与Schizochytrium sp.FJU-512 18S rDNA(GenBank No.AY758384)的同源性最高,为98%~99%;与S.limacinum(GenBank No.AB022107)的同源性为96%;与同属异种S.mangrovei(GenBank No.DQ100293)只有93%的同源性。并运用序列比对分析和MEGA4.0系统进化树,结果显示种内诱变产生的细微变异小于同属内不同物种之间的变异。本研究除了为裂殖壶菌这种重要的经济海洋真菌提供分子生物学资料以外,同时表明18S rDNA序列不仅在分子分类上是一个重要的标志,也可分析由突变引起的物种内细微的遗传变异。

Cloning and analysis of 18S rDNA gene from Schizochytrium limacinum OUC88 and 10 derived strains

18S rDNA genes with length between 1751bp and 1758bp (GenBank : HM042904-HM042914) were cloned from Schizochytrium limacinum OUC88 and its 10 derived strains by PCR. By sequencing and blasting withother 18S rDNA genes of Schizochytrium from GenBank database, the genetic distances of S. limacinum OUC88 and its derived strains were between zero and 0.013, and their identity was between 98% and 99% with Schizochytrium sp FJU-512 (GenBank No. AY758384), 96% with S. limacinum (GenBank No. AB022107) and 93% with S. mangrovei (GenBank No.DQ100293), respectively. By sequence analysis and the phylogenetic tree built up by MEGA4.0, the results showed that slight variation in mutation was less than in different species. These have provided molecular biology data for this important economic marine fungi. Furthmore, the results showed that the 18S rDNA sequence was not only an important sign in molecular classification, but also can be used to analyze slight genetic variation caused by mutation.