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Evolution of antibody diversity in bony vertebrates


Par Cyril - Posté le 17 avril 2014

TitreEvolution of antibody diversity in bony vertebrates
Type de publicationMiscellaneous
Nouvelles publications2001
AuteursRoman T, Lecointre G, Charlemagne J
RésuméThis paper is a rapid description of,the different systems which, in I,osteichthyan vertebrates, led to. antibody diversity. Two in major groups can therefore be distinguished. In the first one, diversity is., mainly obtained by the combinatorial recombination of a large number of the genomic DNA segments that encode the V, (D) and J regions of variable domains of immunoglobulin (Ig) chains. This grout, p includes man, mouse, amphibians and actinopterygians. In the second group, combinatorial diversity cannot operates efficiently, due to the loss of the majority of the genomic V segments. Diversity is thus. obtained by alter native strategies, like gene conversion or somatic hypermutation that, to a lesser extend, also operate in the first group. This second group includes chicken, rabbit, sheep, ox and pig. These two groups obviously have nothing to do with phylogeny. The phylogenetic disparity of the second group suggests that their immunity systems evolved independently I in each domesticated species. As a working hypothesis, we propose that the situation of the second group could be a side effect of artificial selection. All these species are domesticated farm animals which have been selected to improve some phenotypic characters, A possible effect of this selection would be a drastic loss of V genes. This loss of combinatorial diversity was then compensated by alternative strategies of antibody diversification. This hypothesis may help, to elucidate a complex situation and could easily be tested, by analyzing the Ig repertoires in the wild and comparing them to the ones found in,species of the, second group.