| Citation | Almost single handed, Dr. Hodgkin has discovered how sex is determined in the nematode Caenorhabditis elegans. By genetic methods he has defined a series of autosomal genes which determine whether the nematode will be male (XO) or hermaphrodite (XX). This led to his model for the function of these genes: how they respond to the primary sex determining signal - X chromosome dosage - and then act in a regulatory cascade to control sexual phenotype in both somatic and germ-line tissues. A germ-line-specific modulation, acting at a defined step in the cascade, leads to a transient spermatogenesis in larval XX animals, thereby explaining why these are hermaphrodite rather than female (in most nematode species XX animals are females). Dr. Hodgkin and coworkers have now cloned several of the genes in the cascade. The logic of this pathway is one of the most thoroughly understood systems of developmental gene regulation in any animal. He has made other valuable contributions to nematode genetics - in particular, to the understanding of meiosis, dosage compensation, genetic suppression, determination of cell lineage and behaviour. He is one of the world's leading developmental geneticists. |