Born into a prominent Jewish family in Pisa, Pontecorvo was the eldest of six children. (Two of his brothers were the particle physicist Bruno and the film-maker Gillo.) He studied at the University of Pisa, and worked in the Agricultural Research Institute at Florence. Then, in 1938, the rise of Mussolini and the gathering clouds of war in mainland Europe forced Pontecorvo to emigrate to Edinburgh. There he joined the American geneticist H. J. Muller, who had established a group that met regularly in the Institute of Animal Genetics to discuss gene structure and function. Max Born, the well-known theoretical physicist, was a regular participant in these discussions. In 1941, Ponte became a lecturer in zoology at Glasgow University, where he began his work on the fungus Aspergillus nidulans. Four years later he was made head of the newly created genetics department.
Among Pontecorvo's contributions to genetics, two in particular stand out. First, he discovered the parasexual cycle in fungi. In this process, haploid nuclei (which contain one of each chromosome) can fuse to become diploid (containing two copies of each chromosome). In cultured cells of other species, such as man or mouse, diploid cells fuse to give cells with greater numbers of chromosomes. Subsequently, the extra chromosomes may be lost. The consequences are similar to what happens in sexual reproduction, crossing-over and recombination of genes; J. B. S. Haldane has called this an “alternative to sex”. Pontecorvo realized that the phenomenon could be used to figure out the arrangement of genes on chromosomes. He and his colleagues Alan Roper and Ted Forbes developed methods of genetic analysis that were forerunners of modern cell genetics.
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