Developmental progression of immunoglobulin heavy chain diversity in sheep.
In order to assess the respective impacts of combinatorial rearrangement, junctional diversification, somatic hypermutation and gene conversion in the generation of immunoglobulin heavy chain variable regions diversity, the sequences of 42 variable regions from late fetal, newborn and young sheep were determined and compared to those of adult animals. At earlier stages of development, the use of germline diversity segments appears restricted, junctional variability is already established, and somatic hypermutations are scarce. The sequence diversity in adults is much higher, which we suggest results from a higher hymermutation activity and possibly from the use of a variety of diversity segments. Altogether, this pattern is very reminiscent of the situation observed in cattle, except for the length of the third complementarity determining regions (CDR3) which are shorter in sheep than in bovine. Unlike the chicken and rabbit systems, it seems that new rearrangements continue to occur in sheep for at least several months after birth.
Gontier
Etienne
E
Laboratoire d'Immunologie Moléculaire, Faculté des Sciences, EA 2224, IFR 59, Université de Poitiers, 40 Avenue du Recteur Pineau, 86022 Poitiers Cedex, France.
Ayrault
Olivier
O
Godet
Isabelle
I
Nau
François
F
Ladevèze
Véronique
V
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D022801:Complementarity Determining Regions; D015321:Gene Rearrangement; D014644:Genetic Variation; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007135:Immunoglobulin Variable Region / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D016133:Polymerase Chain Reaction; D012756:Sheep / Q000276:immunology*
D022801:Complementarity Determining Regions; D007143:Immunoglobulin Heavy Chains; D007135:Immunoglobulin Variable Region