Molecular Cloning Of BDNF Genes Of Amphibians And Reptiles And Their Application In Phylogeny And Taxonomy

The full coding regions of BDNF genes were amplified from the genome of Tylototriton taliangensis ,Phrynocephalus hongyuanensis,Japalura splendida and Cyclophiops major,respectively by PCR with the primers designed on the sequence of human BDNF gene . The PCR products were cloned into the vector pUCIS of Esherichia coli.Sequence analysis showed that the coding regions of three reptiles are the same (741 bp) in length and these BDNF genes encode a peptide of 246 amino acid residues while that of Tylototriton taliangensis is 744 bp in length and encodes a peptide of 247 amino acid residues. There are no introns in all four genes and the length of the deduced mature BDNF(119 amino acid residues) is the same. The homology of deduced BDNF sequences is over 90% among the three reptiles. But the BDNF sequence of Tylototriton taliangensis with those of other three reptiles showed a little lower homology. Finally,the homology of BDNF gene among the reptiles and the aves is higher than that among reptiles and in other species. Both GenBank blast search and restriction enzyme map analysis reveal that the sequences of BDNF mature peptides from different species are highly conserved during evolution.Phylogeny analysis is performed with PHYLIP software package and encoding sequence of BDNF gene. The phylogeny trees have been drawn with three different methods (maximum parsimony method,genetic distance method and maximum likelihood method),respectively. The analysis outcomes are not all consistent for the reason that it is closely related to the selected methods and the conservative level of the sequences. On the other hand,DNASTAR software was utilized in the analysis of the different segments of BDNF genes. The reasonable phylogenic tree was constructed with the leading peptide encoding sequences.