Involvement of androgen receptor gene in male gonad differentiation in Indian garden lizard, Calotes versicolor

The Indian garden lizard, Calotes versicolor, shows neither cytologically distinguishable sex chromosomes nor temperature dependent sex determination. However, previous studies on the administration of androgens to embryos during early development have shown reversal towards male sex. We have cloned and sequenced a cDNA fragment of the androgen receptor (AR) gene (CvAR) and characterized its expression. CvAR shares much homology with AR gene of other vertebrates at the nucleotide and amino acid levels indicating their evolutionary conservation. Whole mount RNA in situ hybridization (WRISH) and semi-quantitative RT-PCR analyses of its expression in the genital ridge of individual embryos from different stages of development, demonstrate its initiation by day 10 which is later than CvSox9 but occurs dimorphically only in those embryonic gonads which express CvSox9, a male specific marker. It suggests that AR expression may be crucial in the male sex determination pathway in C. versicolor.