SEQUENCE AND GENE ORGANIZATION OF THE CHICKEN MITOCHONDRIAL GENOME - A NOVEL GENE ORDER IN HIGHER VERTEBRATES
SEQUENCE AND GENE ORGANIZATION OF THE CHICKEN MITOCHONDRIAL GENOME - A NOVEL GENE ORDER IN HIGHER VERTEBRATES
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DOI：
10.1016/0022-2836(90)90225-b
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发表时间：
1990-04-20
影响因子：
5.6
通讯作者：
MORAIS, R
中科院分区：
文献类型：
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作者：
DESJARDINS, P;MORAIS, R
白来窝鸡的16775碱基对线粒体基因组已经被克隆并测序。鸟类基因组编码与其他脊椎动物线粒体dna相同的一组基因（13个蛋白质，2个rrna和22个trna），并且以非常相似的经济方式组织。很少有基因间核苷酸，蛋白质或tRNA基因之间有几个重叠的例子。蛋白质基因与哺乳动物和两栖动物的对应基因高度相似，并根据相同的变异遗传密码进行翻译。尽管有这些高度保守的特征，鸡线粒体基因组显示出两个显著的特征。首先，它展示了一种新的基因顺序，相邻的tRNAGlu和ND6基因位于分子的位移环区域附近，就在相邻的tRNAPro、tRNAThr和细胞色素b基因之前，这些基因在其他脊椎动物线粒体基因组中与位移环区域相邻。这种不寻常的基因顺序在加利形鸟类中是保守的。其次，在鸡基因组中没有光链复制起源，相当于迄今为止在所有脊椎动物线粒体基因组中发现的tRNACys和tRNAAsn基因之间的保守序列。这些观察结果表明，在脊椎动物物种的进化过程中，镓形线粒体基因组与哺乳动物和两栖动物的线粒体基因组有所不同。这些意想不到的特征为在更高的分类水平上研究系统发育关系提供了有用的标记。
The 16,775 base-pair mitochondrial genome of the white Leghorn chicken has been cloned and sequenced. The avian genome encodes the same set of genes (13 proteins, 2 rRNAs and 22 tRNAs) as do other vertebrate mitochondrial DNAs and is organized in a very similar economical fashion. There are very few intergenic nucleotides and several instances of overlaps between protein or tRNA genes. The protein genes are highly similar to their mammalian and amphibian counterparts and are translated according to the same variant genetic code. Despite these highly conserved features, the chicken mitochondrial genome displays two distinctive characteristics. First, it exhibits a novel gene order, the contiguous tRNAGlu and ND6 genes are located immediately adjacent to the displacement loop region of the molecule, just ahead of the contiguous tRNAPro, tRNAThr and cytochrome b genes, which border the displacement loop region in other vertebrate mitochondrial genomes. This unusual gene order is conserved among the galliform birds. Second, a light-strand replication origin, equivalent to the conserved sequence found between the tRNACys and tRNAAsn genes in all vertebrate mitochondrial genomes sequenced thus far, is absent in the chicken genome. These observations indicate that galliform mitochondrial genomes departed from their mammalian and amphibian counterparts during the course of evolution of vertebrate species. These unexpected characteristics represent useful markers for investigating phylogenetic relationships at a higher taxonomic level.