Ganesh S, Choudhary B, Raman R
Department of Zoology, Banaras Hindu University, Varanasi, India.
Cytogenet Cell Genet. 1998;80(1-4):89-93. doi: 10.1159/000014962.
A 590-bp long zinc finger domain DNA fragment has been isolated by polymerase chain reaction from the lizard, Calotes versicolor, employing the primers used for amplifying the zinc finger domain of the human Y-chromosomal gene, ZFY. Cloned in pUC18, the fragment, called CvZfa, was sequenced and its expression during development was studied. At the nucleotide and amino acid level CvZfa shows respectively 83% and 90% identity with the human ZFY, but its extent of homology is greater with the ZFX of human (86% at nucleotide and 92% at amino acid level) and the ZFY-like genes of turtle and chick. Similarly its homology with the mouse Zfx and Zfa is much greater than that with Zfy-1 and Zfy-2. It appears that the mammalian ZFX (Zfx) evolved from reptilian ancestors with a considerable degree of conservation, but the ZFX to ZFY divergence within the class mammalia was more rapid. The CvZfa transcripts were seen in all the embryonic stages from which RNA was analysed. The whole mount in situ hybridization with the posteriorly placed mesonephros and the gonadal primordia of 10 to 25 day old embryos showed signal selectively in mesonephros of the 20 and 25 day embryos. There was no signal in the genital ridge. Thus CvZfa may not have a direct role in gonadogenesis of C. versicolor, but the possibility of its inductive role in the formation of adreno-gonadal axis through mesonephros cannot be discounted.
通过聚合酶链反应，利用用于扩增人类Y染色体基因ZFY锌指结构域的引物，从变色树蜥中分离出一段590个碱基对长的锌指结构域DNA片段。该片段克隆于pUC18中，命名为CvZfa，进行了测序并研究了其在发育过程中的表达。在核苷酸和氨基酸水平上，CvZfa与人类ZFY分别具有83%和90%的同一性，但其与人类ZFX（核苷酸水平为86%，氨基酸水平为92%）以及龟和鸡的ZFY样基因的同源程度更高。同样，它与小鼠Zfx和Zfa的同源性远高于与Zfy - 1和Zfy - 2的同源性。看来哺乳动物ZFX（Zfx）从爬行动物祖先进化而来，具有相当程度的保守性，但在哺乳纲内ZFX到ZFY的分化更为迅速。在所有分析RNA的胚胎阶段都能看到CvZfa转录本。对10至25日龄胚胎后置的中肾和性腺原基进行的全胚胎原位杂交显示，在20日和25日胚胎的中肾中有选择性信号。生殖嵴中没有信号。因此，CvZfa可能在变色树蜥的性腺发生中没有直接作用，但不能排除其通过中肾在肾上腺 - 性腺轴形成中起诱导作用的可能性。
