Spruyt N, Delarbre C, Gachelin G, Laudet V
CNRS UMR 319, Mécanismes du Développement et de la Cancérisation, Institut de Biologie de Lille, Institut Pasteur, 1 rue Calmette, 59021 Lille, France.
Nucleic Acids Res. 1998 Jul 1;26(13):3279-85. doi: 10.1093/nar/26.13.3279.
The complete nucleotide sequence of the mitochondrial DNA of the amphioxus Branchiostoma lanceolatum has been determined. This mitochondrial genome is small (15 076 bp) because of the short size of the two rRNA genes and the tRNA genes. In addition, this genome contains a very short non-coding region (57 bp) with no sequence reminiscent of a control region. The organisation of the coding genes, as well as of the two rRNA genes, is identical to that of the sea lamprey. Some differences in the repartition of the tRNA genes occur when compared to the lamprey. The mitochondrial codon usage of the amphioxus is reminiscent of that of urochordates since the AGA codon is read as a glycine and not as a stop codon as in vertebrates. Moreover, the base composition at the wobble positions of the codon is strongly biased toward guanine. Altogether, these data clearly emphasise the close relationships between amphioxus and vertebrates, and reinforce the notion that prochordates may be viewed as the brother group of vertebrates.
文昌鱼(Branchiostoma lanceolatum)线粒体DNA的完整核苷酸序列已被确定。由于两个rRNA基因和tRNA基因的长度较短,该线粒体基因组较小(15076 bp)。此外,该基因组包含一个非常短的非编码区(57 bp),没有与控制区相似的序列。编码基因以及两个rRNA基因的组织方式与海七鳃鳗相同。与七鳃鳗相比,tRNA基因的分布存在一些差异。文昌鱼的线粒体密码子使用情况让人联想到尾索动物,因为AGA密码子被解读为甘氨酸,而不是像在脊椎动物中那样作为终止密码子。此外,密码子摆动位置的碱基组成强烈偏向鸟嘌呤。总之,这些数据清楚地强调了文昌鱼与脊椎动物之间的密切关系,并强化了原索动物可被视为脊椎动物姐妹类群的观点。