Black W C, Roehrdanz R L
Department of Microbiology, Colorado State University, Fort Collins 80523, USA.
Mol Biol Evol. 1998 Dec;15(12):1772-85. doi: 10.1093/oxfordjournals.molbev.a025903.
The entire mitochondrial genome was sequenced in a prostriate tick, Ixodes hexagonus, and a metastriate tick, Rhipicephalus sanguineus. Both genomes encode 22 tRNAs, 13 proteins, and two ribosomal RNAs. Prostriate ticks are basal members of Ixodidae and have the same gene order as Limulus polyphemus. In contrast, in R. sanguineus, a block of genes encoding NADH dehydrogenase subunit 1 (ND1), tRNA(Leu)(UUR), tRNA(Leu)(CUN), 16S rDNA, tRNA(Val), 12S rDNA, the control region, and the tRNA(Ile) and tRNA(Gln) have translocated to a position between the tRNA(Glu) and tRNA(Phe) genes. The tRNA(Cys) gene has translocated between the control region and the tRNA(Met) gene, and the tRNA(Leu)(CUN) gene has translocated between the tRNA(Ser)(UCN) gene and the control region. Furthermore, the control region is duplicated, and both copies undergo concerted evolution. Primers that flank these rearrangements confirm that this gene order is conserved in all metastriate ticks examined. Correspondence analysis of amino acid and codon use in the two ticks and in nine other arthropod mitochondrial genomes indicate a strong bias in R. sanguineus towards amino acids encoded by AT-rich codons.
对一种硬蜱科前气门亚目蜱（六角硬蜱）和一种后气门亚目蜱（血红扇头蜱）的整个线粒体基因组进行了测序。两种基因组都编码22种转运RNA、13种蛋白质和两种核糖体RNA。前气门亚目蜱是硬蜱科的基部成员，其基因排列顺序与美洲鲎相同。相比之下，在血红扇头蜱中，编码NADH脱氢酶亚基1（ND1）、亮氨酰-tRNA（UUR）、亮氨酰-tRNA（CUN）、16S核糖体DNA、缬氨酰-tRNA、12S核糖体DNA、控制区以及异亮氨酰-tRNA和谷氨酰胺-tRNA的一组基因已经转移到了谷氨酸-tRNA和苯丙氨酸-tRNA基因之间的位置。半胱氨酰-tRNA基因转移到了控制区和甲硫氨酰-tRNA基因之间，亮氨酰-tRNA（CUN）基因转移到了丝氨酰-tRNA（UCN）基因和控制区之间。此外，控制区发生了重复，且两个拷贝经历协同进化。位于这些重排两侧的引物证实，这种基因排列顺序在所检测的所有后气门亚目蜱中都是保守的。对这两种蜱以及其他九个节肢动物线粒体基因组中氨基酸和密码子使用情况的对应分析表明，血红扇头蜱对由富含AT的密码子编码的氨基酸存在强烈偏好。
