Comparative Genetics of Complex Loci

Investigators of complex loci or pseudoalleles have attempted to analyze the structure and functions of the gene by the use of multiple allelic series. In the past decade a number of studies have presented stimulating findings and interpretations on the biochemical, topological, and physiological properties of genes. The historical background which led to these new discoveries is summarized and the basic problems involved are sketched. All of the present examples in Drosophila melanogaster are individually considered for their unique features as well as their similarities. The problem of the universality of pseudo-allelism is considered, with numerous examples of complexity in gene regions chosen from a wide variety of cellular forms. Special attention is also given to the interpretations of blood groups. In the microorganisms the contributions from viruses, bacteria, and the fungi are contrasted with the findings in the higher organisms. The major differences and basic similarities are pointed out in a comparative analysis of the various theories used to interpret the gene concept.