A Comprehensive in silico DNA Sequence Analysis of Sperm Surface ADAM Genes Collected from RefSeq Database

The objective of the present study is to provide a comprehensive in silco sequence analyses of sperm-surface ADAM genes using the curated and nonredundant RefSeq database. 36 complete refseq CDS (coding sequence) of 9 members of ADAM gene family namely ADAM1,2,3,4,5,6,18,24 and 32 were obtained to investigate its evolution and differentiation within and among species. Among the 9 sperm-surface genes ADAM1 has the longest CDS length, the highest GC% and largest variation in base composition. Measurement of polymorphism and genetic diversity (e.g. Number of haplotypes, nucleotide diversity (π) and average number of nucleotide diversity) varied greatly among the sperm-surface ADAM genes. These large variations are evidence for the effect of selection pressure on these genes. The phylogenetic analysis displayed clearly the resolved relationship of sperm-surface ADAM genes and most of bootstrap support were high. Sperm-surface ADAM genes were classified into 6 clades where, ADAM1,2,3,4,5,6,18,24 and ADAM32 of B.taurus and H. sapiens categorizing to one large lineage where ADAM32 of R. norvegicus and M. musculus belonging to another separate lineage. In conclusion, the in silico analysis of the 9 sperm-surface ADAM genes showed a great deal of variation among and within this genes indicating the presence of localized signals of selection pressure on these genes. Moreover, ADAM1,4,6 and 24 have no human orthologues. More importantly, our results suggested that ADAM1,2,3,4,5,6, 18,24 and ADAM32 of B.taurus and H. sapiens were descendent form one ancient ancestor, where ADAM32 of R. norvegicus and M. musculus have another ancestor.