REARRANGEMENT HYPERMUTATION/GENE CONVERSION - WHEN, WHERE AND WHY/

Diversification strategies for immunoglobulins vary widely in differen t species. Here, Jean-Claude Weill and Claude-Agnes Reynaud argue that V(D)J recombination arose as a means for achieving allelic exclusion rather than diversity, and postulate that the choice of a diversificat ion strategy is selected along with a specific site of B-cell differen tiation. They propose that somatic mutation and gene conversion repres ent analogous molecular strategies occurring in specific chromatin acc essibility contexts.