V genes in rodents from whole genome sequencing data

We studied the V exons of 14 rodent species obtained from whole genome sequencing (WGS) datasets. Compared to other mammals, we found an increase in the number of immunoglobulin (IG) V genes in the heavy (IGH) and kappa chain (IGK) loci. We provide evidence for a reduction genes in lambda chain (IGL) locus, disappearing entirely in one of the species(Dipodomys ordii). We show relationships amongst the V genes of the T-cell receptors (TR) found in primates, possessing ortholog sequences between them. As compared with other mammals, there is an increase in the number of TRAV genes within rodents. Such an increase within this locus is caused by duplication events involving a few putative V genes. This duplication phenomenon does not occur in the TRBV locus. In those species that underwent an expansion of TRAV genes, we found that they also have a correspondingly larger number of MHC Class I genes. The results suggest that selective pressures have conditioned the expansion of V genomic repertoire the TRA, IGK and IGH loci during the diversification process of rodents.