| In order to identify molecular events characteristic of gene family evolution, we have studied polymorphism in the mouse beta globin cluster. A restriction fragment length polymorphism was detected in the vicinity of the Mus musculus domesticus bh0 gene. Here we demonstrate that a deletion of the majority of the bh0 gene as well as a small insertion of AT rich DNA in the Hbb;Our comparative studies have identified an unexpected deletion of a dispensable gene. We interpret the novel structure of the deletion junction and breakpoints as evidence for an illegitimate recombination and propose a mechanism to account for our observations. In addition, we have identified at least two alternative fates of a dispensable gene. Although not diverging at the characteristic accelerated rate, we suggest that the bh0 gene is to all intents and purposes a pseudogene. In contrast the partially deleted gene represents the elimination of non-essential information.;We found the partially deleted gene to be highly conserved, differing no more from the intact allele than would be expected of a functional gene. Although conservation of sequence might be interpreted as evidence for a recent deletion (with respect to the Mus species), the presence of the partially deleted bh0 gene in both commensal (M. m. musculus and M. m. domesticus) as well as the aboriginal species (M. spretus) suggests that the deletion predates the commensal/aboriginal split approximately 3-4 MY ago. |
