This preliminary work will test ideas concerning the importance of recombination signal-sequence directed V(D)J joining of immunoglobulin and T-cell receptor gene segments in the evolution of immunity and self/non-self recognition. The immediate goal of the proposal is to develop conditions for microinjecting artificial recombination signal-sequence directed, DNA recombination substrates in an in vivo model system, the protochordate, Botryllus. Botryllus, a colonial tunicate which displays histocompatibility, is ideally suited for studies of the evolution of major histocompatibility complex and lymphocyte receptor recognition. Success with this project should have a major impact. Not only will this study provide information about the evolution of self/non-self recognition, potentially yielding sequence information for primordial immunoglobulin and/or T-cell receptor genes, it may also demonstrate a conserved mechanism, the generation of receptor diversity by gene rearrangement. Although this project involves a novel approach, the potential payoff in determining whether the invertebrate to vertebrate transition involves, or is accompanied by, the acquisition of gene- rearranging machinery is worth the admittedly high risk.
