Bottlenose dolphin (Tursiops truncatus) and the other cetaceans represent the most successful mammalian colonization of the aquatic environment and have undergone a radical transformation from the original mammalian bodyplan. The discovery of two archaic whales with morphological homology between Cetacea and Artiodactyla brought conclusive anatomical support to clade Cetartiodactyla. Whales and hippos shared a common semiaquatic ancestor that branched off from other artiodactyls around 60 million years ago. One of the two branches would evolve into cetaceans, possibly beginning about 52 million years ago, with the protowhale Pakicetus, which underwent aquatic adaptation into the completely aquatic cetaceans. The only studies of antigen receptors immunity revealed that IgG are present in whales and IGHG and IGHA genes have been described in the Atlantic bottlenose dolphin. So far nothing is known about the genomic organization of dolphin T cell receptor loci. Within artiodactyls, the locus organization and expression of T cell receptor gamma (TRG) and delta (TRD) genes have been well characterized in ruminants. Here we present a evolutionary and expression analysis of Tursiops truncatus TRG and TRD genes. The surprising feature concerning TRG genes was, on the one hand, that the overall organization of the dolphin TRG locus resembles more the structure of a typical cassette of artiodactyls (IMGT®, the international ImMunoGeneTics information system®, http://www.imgt.org > Locus representation: Sheep (Ovis aries) TRG1) than the structure typical of the human locus (IMGT® > Locus representation: Human (Homo sapiens) TRG). On the other hand, equally surprising was the finding of an unusual mechanism of biases in the V-J gene rearrangement usage, which is reminiscent of that by far, the most frequently used in the human peripheral γδ T cells repertoire of productively rearranged TRGV genes. Despite the fragmented nature of the assembly, we have obtained important information on the genomics and the evolution of the TRD dolphin potential repertoire and its relationship with the expressed chains. cDNA analysis of blood and skin from four unrelated subjects, revealed sharing of in-frame TRG sequences within the same and in different individuals living in a controlled environment (kept under human care) as well as in marine environment, suggesting in dolphin the existence of a basic “public” γδ repertoire of a given TR in a range of public T cell responses. We conclude that in dolphins as in human, the gamma delta TCR repertoire is accompanied by selection for public gamma chain.
Dolphin (Tursiops truncatus) T cell receptor gamma (TRG) and delta (TRD) chains repertoire
Linguiti, G.;ANTONACCI, Rachele;CICCARESE, Salvatrice Maria
2016-01-01
Abstract
Bottlenose dolphin (Tursiops truncatus) and the other cetaceans represent the most successful mammalian colonization of the aquatic environment and have undergone a radical transformation from the original mammalian bodyplan. The discovery of two archaic whales with morphological homology between Cetacea and Artiodactyla brought conclusive anatomical support to clade Cetartiodactyla. Whales and hippos shared a common semiaquatic ancestor that branched off from other artiodactyls around 60 million years ago. One of the two branches would evolve into cetaceans, possibly beginning about 52 million years ago, with the protowhale Pakicetus, which underwent aquatic adaptation into the completely aquatic cetaceans. The only studies of antigen receptors immunity revealed that IgG are present in whales and IGHG and IGHA genes have been described in the Atlantic bottlenose dolphin. So far nothing is known about the genomic organization of dolphin T cell receptor loci. Within artiodactyls, the locus organization and expression of T cell receptor gamma (TRG) and delta (TRD) genes have been well characterized in ruminants. Here we present a evolutionary and expression analysis of Tursiops truncatus TRG and TRD genes. The surprising feature concerning TRG genes was, on the one hand, that the overall organization of the dolphin TRG locus resembles more the structure of a typical cassette of artiodactyls (IMGT®, the international ImMunoGeneTics information system®, http://www.imgt.org > Locus representation: Sheep (Ovis aries) TRG1) than the structure typical of the human locus (IMGT® > Locus representation: Human (Homo sapiens) TRG). On the other hand, equally surprising was the finding of an unusual mechanism of biases in the V-J gene rearrangement usage, which is reminiscent of that by far, the most frequently used in the human peripheral γδ T cells repertoire of productively rearranged TRGV genes. Despite the fragmented nature of the assembly, we have obtained important information on the genomics and the evolution of the TRD dolphin potential repertoire and its relationship with the expressed chains. cDNA analysis of blood and skin from four unrelated subjects, revealed sharing of in-frame TRG sequences within the same and in different individuals living in a controlled environment (kept under human care) as well as in marine environment, suggesting in dolphin the existence of a basic “public” γδ repertoire of a given TR in a range of public T cell responses. We conclude that in dolphins as in human, the gamma delta TCR repertoire is accompanied by selection for public gamma chain.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
