Is recombination confined to structural genes on the eukaryotic genome?

Abstract

THE size of the eukaryotic genome increases with the evolutionary complexity of the organism, although this relation is somewhat obscured by large differences in the haploid DNA content of closely related species. Yet the total number of genes is believed to be fairly constant, suggesting that genes of higher eukaryotes correspond to much larger DNA segments than in microorganisms1. In that case, only a small fraction of each gene would code for the ultimate gene product, the remainder being ‘spacer’ DNA with still ill-defined functions. The sequence coding for the gene product will be hereafter designated as the structural gene. The complex organisation of chromatine in higher organisms raises the problem of its possible influence on the distribution of recombination events. I shall present here evidence suggesting that they may well be restricted to small regions of the genome, possibly corresponding to the structural genes.