The chromosomal region constituting the major histocompatibility comple (Mhc) has undergone complex evolution which is often difficult to decipher. An important aid in the elucidation of the Mhc evolution is the presence of Alu elements (repeats) which serve as markers for tracing chromosomal rearrangements. As the first step toward the stablishment of sets of evolutionary markers for the Mhc, Alu elements present in selected Mhc haplotypes of different prosimians species will be identified.
Restriction fragments of lambda phage clones from the libraries of thos mentioned species will be hybridized with Alu-specific probes, Alu elements will be amplified by the polymerase chain reaction (PCR), and the amplification products subsequently sequenced. Assignments of the Alu elements obtained to the different specific-families will be done and then, putative duplication times of the different DRB genes stablished. Finally, comparison of Alu content in prosimians and primates will help to decipher the evolutionary mechanisms driving the actual composition and differential localisation of the Mhc-DRB genes.