New alleles are accumulating rapidly in living populations and cellular mechanisms have not been adequately sought to explain the intentional production of these changes. Homologous DNA recombination occurs in all organisms and is at the heart of genetics. Since its discovery during meiosis, these reactions were assumed to occur randomly along the length of chromosomes, and only involved with gene crossovers. It is now well known that meiotic recombination is not the random process it was originally assumed to be, and controlled by highly organized regulatory systems. In addition, a form of homologous recombination has been discovered which is responsible for creating diversity in variable genes, and was recently linked to single base-pair substitutions in immunoglobulins. New allele formation may indeed be the key to explaining the rapid production of distinct breeds, but their presence in the genome has been assumed the result of random mutations. Therefore, the ability of the cel... more
