title: Primary structure and variation of the T-cell receptor delta-chain from a marsupial, Macropus eugenii.
abstract: Although gammadelta T-cells form only a small portion of circulating T-cells in mice and humans, they are more frequent in many other types of mammals and this has lead to speculation regarding their roles and the evolutionary significance of their relative abundance. Moreover, whilst clear homologues of four types of T-cell receptor (TCR) chains (alpha, beta, delta and gamma) have been identified in vertebrates as distantly related as eutherian mammals and cartilaginous fish, there are still many gaps in our knowledge of these TCR components from various taxa. Such knowledge would further illuminate the evolution and function of these receptors and of gammadelta T-cells. Here, we report the molecular cloning of a TCR-delta chain cDNA from the tammar wallaby (Macropus eugenii) which represents the first component of the gammadelta TCR to be characterised from a marsupial. A PCR-based survey of variable (V) segment usage in tammar wallaby mammary-associated lymph node indicated that, although gammadelta T-cells may be sparse in this type of tissue, this species has at least three subfamilies of V genes that have been broadly conserved across vertebrate evolution. Two V subfamilies found in the tammar wallaby were relatively similar and may have diverged more recently, an event that probably occurred at some point in the marsupial lineage.
authors.affiliation: School of Science, Food and Horticulture, University of Western Sydney, BCRI Building, Locked Bag 1797, Penrith South DC, NSW 1797, Australia.
authors.forename: Gavan A
authors.initials: GA
authors.lastname: Harrison
authors.forename: Charlotte L
authors.initials: CL
authors.lastname: Taylor
authors.forename: Robert D
authors.initials: RD
authors.lastname: Miller
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Deane
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D017124:Conserved Sequence / Q000235:genetics; D019143:Evolution, Molecular; D006801:Humans; D008394:Marsupialia / Q000235:genetics* / Q000276:immunology*; D051379:Mice; D008969:Molecular Sequence Data; D010802:Phylogeny; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000737:chemistry* / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
chemical_list: D016692:Receptors, Antigen, T-Cell, gamma-delta