CLONING AND SEQUENC ING DM DOMA IN OF THE DM RT GENE FROM THE CHINESE GIANT SALAMANDER, ANDRIAS DAV ID IANUS

The Dmrt genes constitute a new gene family related to sex-determination, which encoded putative transcription factorswith a conserved DM domain that initiates genetic process in early development through itsDNA binding ability. So far, the Dmrt genes have been discovered in awide range of animal species, such as fish, amphibian, reptiles, birds, and mammals, which evidently revealed the evolutionary conservation of Dmrt gene family. Amphibians is a key in the evolu-tion during the aquatic and the terrestrial, the research of Dmrt gens in Andrias davidianus, which was a very important group in phylogenic evolution, has not been reported. In order to confirm the evolutionary conservation ofDmrt gen family in Andrias davidianus, degenerate PCR primers, designed from a highly conserved region of aligned multiple sequences, was successfully used for the amplification of the DM domain of the Dmrt gene from the Chinese giant salamander (Andrias davidianus). A DNA fragmentwith about 140 bp in length was obtained by PCR using A. davidianus genomic DNA as template. The DNA was cloned and its nucleotideswere determined by sequencing. Homology searching against databases confirmed its identity as Dmrt gene fragment from the A. davidianus. The sequence comparison analysis showed that the Andrias Dmrt shared high sequence similaritywith Dmrt genes from M acaca mulatta (91%), Oryzias latipes (92%), Ho-mo sapiens (92%), M us musculus (89%), Bos taurus (91%) and Xenopus tropicalis (84%), but its amino acid se-quence remained at a similar level with other Dmrts (91%). The Arginine of location 19, 34, 36 and 45 was replaced with cysteine, Glutamine, Tryptophane and Glutamine respectively. The results further indicated that Dmrt genes were highly conserved in phylogeny and the strong evolutionary conservation of this gene family suggested thatDmrt genesmight be importance in developmental process.