探讨rDNA ITS区作为果蝇Drosophila nasuta分子系统发育研究的价值  

A Study of ITS Sequence as a Molecular Marker in the Phylogeny of Drosophila nasuta Subgroup

作　　者：俞海菁[1] 林飞栈[2] 张亚平[1] 朱定良[3] 庚镇城[3] 

机构地区：[1]中国科学院昆明动物研究所细胞及分子进化开放实验室,昆明650223 [2]台湾中央研究院动物研究所 [3]上海复旦大学遗传研究所,上海200433

出　　处：《Acta Genetica Sinica》2000年第1期18-25,共8页

基　　金：国家自然科学基金;中国科学院昆明动物研究所细胞与分子进化开放实验室基金

摘　　要：测定了果蝇ｎａｓｕｔａ亚群７个分类元和外群Ｄ ．ｉｍｍｉｇｒａｎｓ的核糖体基因转录间隔区 （ＩＴＳ， ｉｎｔｅｒｔｒａｎｓｃｒｉｂｅｄ ｓｐａｃｅｒ），包含５．８ＳｒＤＮＡ和２Ｓ ｒＤＮＡ长约１．１ｋｂ的ＤＮＡ片段序列。结 果表明：Ｄ．ｐａｌｌｉｄｉｆｒｏｎｓ、Ｔａｘｏｎ　Ｌ Ｔｕｏｎ　Ｊ享有共同的序列；Ｄ．ａｌｂｏｍｉｃａｎｓ则与Ｄ．ｓ． ｎｅｏｎａｓｕｔａ共享１个序列。序列之间存在少量的插入缺失和碱基替代。其中插入和缺失主要发 生内外群之间，内群中只有Ｄ．ｎｉｖｅｉｆｒｏｎｓ发生１个碱基的插入和１２个碱基的缺失以及Ｄ．ｓ． ｓｕｌｆｕｒｉｇａｓｔｅｒ序列中１个碱基的缺失；而在包括外群在内的碱基替代中，共有５５次转换，６５次 颠换，转换／颠换值与动物线粒体基因组十分不同。采用简约法和邻接法构建这７个分类元 的系统发育关系。发现 Ｄ．ｎｉｖｅｉｆｒｏｎｓ位于树的基部，与其他物种有较远的亲缘关系；Ｄ． ａｌｂｏｍｉｃａｎｓ、Ｄ． ｓ． ｎｅｏｎａｓｕｔａ、Ｄ． ｐａｌｌｉｄｉｆｒｏｎｓｓ、Ｔａｘｏｎ　Ｉ、Ｔａｘｏｎ Ｊ最接近，它们是亲缘关系最近的种类。讨论了Ｄ．ｓ．ｓｕｌｆｕｒｉｇａｓｔｅｒ和Ｄ ．ｓ． ｎｅｏｎａｓｕｔａ相互接?A total of 1.1kb including whole ITS (intertranscribed spacer), part of 5.8S rDNA and 2S rDNA were sequenced. The results reveal that D. pallidifrons, Taxon I and Taxon J share the same sequence, and D. albomicans and D. s. neonasuta have the other same one. Among the sequences, there were a handful of insertions, deletions and substitutions. Insertions and deletions occur mainly between outgroup and ingroups, yet only 1 insertion and 12 deletions were detected in D. niveifrons, and I deletion was found in D. s. suglfurigasterr. Among all the sustitutions in outgroup and ingroups, totally 55 transitions and 65 transvertions were detected. The value of transition transvertion is quite different to that of mitochondrial genome. We applied parsimony and NJ methods to reconstruct the phylogenetic relationships of the 7 taxa. They show that D. niveifrons is on the basis of the trees, which suggests that it be less related to the rest; D. albomicans, D. s. neonasuta, D. pallidifrons, Taxon I and Taxon J are more related. We suggested that more related topology of D. s. sulfurigaster and D. s. neonasuta due to the specific evolution of ITS, yet not meaning their real relationships. Sequence variations and phylogeny analysis reveal that the ITS may be not an informative marker to nasuta subgroup. However, sencondary structure analysis by using PCFOLD 4.0 reveals that the structure of the ITS is quite conservative, the stem-1oop of ITS 3'-end may be an important structure of rDNA splicing.

关 键 词：果蝇nasuta亚群 核糖体DNA 系统发育树 

分 类 号：Q953[生物学—动物学]