Siverajah S, Ryce C, Morrison D A, Ellis J T
Department of Cell and Molecular Biology, University of Technology, Sydney, Westbourne St, Gore Hill, NSW 2065, Australia.
Parasitology. 2003 Jun;126(Pt 6):561-9.
The gene coding for a tubulin has been isolated by the polymerase chain reaction and sequenced from 2 isolates of Neospora caninum (Nc-Liverpool and Nc-SweB1). The data show that the gene, as in Toxoplasma gondii, is single copy and contains 3 exons and 2 introns and is identical in sequence in the 2 isolates studied. Comparison of the predicted protein sequence shows it to be identical to the a tubulin protein encoded by the T. gondii gene. The majority of the nucleotide substitutions that have occurred during the evolution of the T. gondii and N. caninum genes from their common ancestor have occurred in the third codon position. A partial coding sequence for a tubulin was also obtained from Hammondia heydorni and compared to other a tubulin sequences from Apicomplexa. The results show the sequences of the T. gondii, N. caninum and H. heydorni a tubulin genes to be similar but not identical in sequence, thereby providing new evidence that N. caninum and H. heydorni are genetically distinct species.
通过聚合酶链反应分离出编码微管蛋白的基因，并对犬新孢子虫的两个分离株（Nc-Liverpool和Nc-SweB1）进行了测序。数据表明，该基因与刚地弓形虫一样，是单拷贝的，包含3个外显子和2个内含子，在所研究的两个分离株中序列相同。预测的蛋白质序列比较表明，它与刚地弓形虫基因编码的α微管蛋白相同。从它们的共同祖先进化而来的刚地弓形虫和犬新孢子虫基因中发生的大多数核苷酸替换发生在第三密码子位置。还从海氏哈蒙德虫中获得了α微管蛋白的部分编码序列，并与来自顶复门的其他α微管蛋白序列进行了比较。结果表明，刚地弓形虫、犬新孢子虫和海氏哈蒙德虫的α微管蛋白基因序列相似但不相同，从而提供了新的证据，证明犬新孢子虫和海氏哈蒙德虫是基因不同的物种。
