Immunoglobulins, MHC and T Cell receptors genes in Cetaceans

Cetaceans correspond to mammals that have returned to the marine environment. Adaptive changes are very significant with the conversion of the limbs into flippers. It is studied the changes that have occurred in immunoglobulins, MHC class I and II and T cell receptors genes. Constant regions of immunoglobulins are similar to those of the rest of mammals. An exception is the IgD gene, which is composed of three CH domains but CH1 similar to CH1 of immunoglobulin M. In the IGHV locus, it exist a decrease in the number of VH genes with the absence of genes within Clan I. The number of V λ genes is greater than that of V κ . In the genes for T lymphocyte receptors, it exists a decrease in the number of V α genes with loss of significant clades and subclades. In V β and V γ , there is also the loss of clades. These declines of V α , V β and V γ are not present Artiodactyla, and they are specific to Cetaceans. In MHC present tree evolutive lines of class I genes. These species have DQ, DR, DO and DM genes, but they are no present DP genes.