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.

1.
Altschul SF, Gish W, Miller W, Myers EW, Lipman DJ: Basic local alignment search tool. J Mol Biol 215:403–410 (1990).
2.
Ashworth A, Skene B, Swift S, Lovell-Badge R: Zfa is an expressed retrotransposon derived from an alternative transcript of the Zfx gene. EMBO J 9:1529–1534 (1990).
3.
Buer M, Gu S, McLaren A: Mesonephric contribution to testis differentiation in the foetal mouse. Development 117:273–281 (1992).
4.
Bull JJ, Hills DMH, O’Steen S: Mammalian ZFY sequences exist in reptiles regardless of sex determining mechanisms. Science 242:567–569 (1988).
5.
Chomczymski P, Saachi N: Single-step method of RNA isolation by acid guanidium thiocyanate-phenol-chloroform extraction. Anal Biochem 162:156–159 (1987).
6.
Gaitonde SG, Gouder BYM: The structure and steroidogenic potential of the developing gonad interrenals in the tropical oviparous lizard, Calotes versicolor (Daud). Reprod Nutri Dev 6:915–926 (1984).
7.
Ganesh S: Molecular and developmental analyses of differentiation of sex in the reptile, Calotes versicolor. Doctoral dissertation, Banaras Hindu University, Varanasi (1996).
8.
Ganesh S, Mohanty J, Raman R: Male-biased distribution of the human Y chromosomal genes SRY and ZFY in the lizard Calotes versicolor, which lacks sex chromosomes and temperature-dependent sex determination. Chrom Res 5:413–419 (1997).
9.
Ganesh S, Raman R: Sex reversal by testosterone and not by estradiol or temperature in Calotes versicolor, the lizard lacking sex chromosomes. J Exp Zool 271:139–144 (1995).
10.
Ganesh S, Raman R: CvSox-4, the lizard homologue of human SOX4 gene, shows remarkable conservation among the amniotes. Gene 196:287–290 (1997).
11.
Koopman P, Ashworth A, Lovell-Badge R: The ZFY family in human and mice. Trend Genet 7:132–136 (1991).
12.
Lloyd SL, Sargent CA, Chalmers J, Lim E, Habeebu SSM, Affara NA: An X-linked zinc finger gene mapping to Xq21.1→q21.3 closely related to ZFX and ZFY: possible origins from a common ancestral gene. Nucl Acids Res 19:4835–4841 (1991).
13.
Luoh SW, Bain PA, Polakiewicz D, Goodheart ML, Gardner H, Jaenisch R, Page D: Zfx mutation results in small animal size and reduced germ cell number in male and female mice. Development 124:2275–2284 (1997).
14.
Martineau J, Nordqvist K, Tilmann C, Lovell-Badge R, Capel B: Male-specific cell migration into the developing gonad. Curr Biol 7:958–968 (1997).
15.
Nagamine CM, Chan K, Hake LLE, Lau YFC: The two candidate sex-determining Y genes (Zfy-1 and Zfy-2) are differentially expressed in the foetal and adult mouse tissues. Genes Dev 4:63–74 (1990).
16.
Page DC, Mosher R, Simpson EM, Fisher EM, Mardon G, Pollack J, McGillivary B, de la Chapelle A, Brown LG: The sex determining region of the human Y chromosome encodes a finger protein. Cell 51:1091–1104 (1987).
17.
Schafer AJ, Goodfellow PN: Sex determination in humans. Bioessays 18:955–963 (1996).
18.
Shimmin CL, Change BHJ, Li W-H: Contrasting rates of nucleotide substitution in the X-linked zinc finger genes. J Mol Evol 39:569–578 (1994).
19.
Sinclair AH, Berta P, Palmer MS, Hawkins JR, Griffiths BL, Smith MJ, Frischauf AM, Lovell-Badge R, Goodfellow PN: A gene from the human sex determining region encodes a protein with homology to a conserved DNA binding motif. Nature 346:240–244 (1990).
20.
Smith CA, Joss JMP: Sertoli cell differentiation and gonadogenesis in Alligator mississippiensis. J Exp Zool 270:57–70 (1994).
21.
Vallely EMA, Muller U, Ferguson MWJ, Sharpe PT: Cloning and expression analysis of two ZFY-related zinc finger genes from Alligator mississippiensis, a species with temperature dependent sex determination. Gene 119:221–228 (1992).
22.
Wilkinson DG: In situ hybridization, in Stern CD, Holland PWH (eds): Essential Developmental Biology – A Practical Approach (Oxford University Press, New York 1993).
1998
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