Platypus TCRm Provides Insight into the Origins and Evolution of a Uniquely Mammalian TCR Locus

Platypus TCRμ provides insight into the origins and evolution of a uniquely mammalian TCR locus.

TCRμ is an unconventional TCR that was first discovered in marsupials and appears to be absent from placental mammals and nonmammals. In this study, we show that TCRμ is also present in the duckbill platypus, an egg-laying monotreme, consistent with TCRμ being ancient and present in the last common ancestor of all extant mammals. As in marsupials, platypus TCRμ is expressed in a form containing...

O-44: Characterisation of Monotreme CaseinsReveals Lineage Specific Expansion of an AncestralCasein Locus in Mammals

Background: One important reproductive characteristic of Mammals is the production of milk to nurse the neonate. In order to better understand the evolution of milk we have investigated gene expression in milk cells from monotremes which are the most ancient representative of the mammalian lineage. Materials and Methods: Using a milk cell cDNA sequencing approach we characterise milk protein se...

A Model for the Evolution of the Mammalian T-cell Receptor α/δ and μ Loci Based on Evidence from the Duckbill Platypus

The specific recognition of antigen by T cells is critical to the generation of adaptive immune responses in vertebrates. T cells recognize antigen using a somatically diversified T-cell receptor (TCR). All jawed vertebrates use four TCR chains called α, β, γ, and δ, which are expressed as either a αβ or γδ heterodimer. Nonplacental mammals (monotremes and marsupials) are unusual in that their ...

A second TCRδ locus in Galliformes uses antibody-like V domains: insight into the evolution of TCRδ and TCRμ genes in tetrapods.

Analyses of the available avian genomes revealed the presence of a second TCRδ locus in the Galliformes. This second TCRδ locus is nonsyntenic to the conventional TCRα/δ and is unusual in that the V genes are more related to IgH V genes (VH) than to TCR V genes. The second TCRδ is not found in another avian lineage, the passerine zebra finch. Rather the finch's conventional TCRα/δ locus contain...

A Second TCRd Locus in Galliformes Uses Antibody-like V Domains: Insight into the Evolution of TCRd and TCRm Genes in Tetrapods