Physical mapping of T cell receptor loci (TRA, TRB, TRD and TRG) in the opossum (Monodelphis domestica).
Deakin, J. E., Parra, Z.E., Graves, J.A.M., Miller, R. D.
Abstract:
Comparative gene mapping between marsupials and eutherians provides insight into the evolution of the mammalian genome. The opossum (Monodelphis domestica) is the first marsupial to be sequenced yet surprisingly very few genes have been physically mapped in this species.
The T cell-mediated immune response plays an important role in antigen recognition in the vertebrate immune system. T cells can be grouped into two subsets, αβ and γδ, based on the expression of T cell receptor α (TRA) and β (TRB) chains, or γ (TRG) and δ (TRD) chains, respectively. Opossum orthologues of TRA, TRB and TRD loci have been previously isolated and characterized at the cDNA level. Opossum TRG sequences have been identified in the current M. domestica genome sequence assembly. Here we have isolated BAC clones containing TRA, TRB, TRD and TRG and localized them to opossum chromosomes. Opossum TRA and TRD co-localize to 1p whereas TRB and TRG map to 8q and 6q respectively. The co-localization of TRA and TRD is consistent with the TRD genes being nested within the TRA locus in the opossum genome, which is identical to the arrangement found in eutherians. These data will in assist in assigning opossum genome sequence data to chromosomes.