Dance of the Yeast Genome

Courtesy of University of California, San Francisco

The science of yeast genetics was still in its infancy some 30 years ago, and one of its thorniest problems wouldn't go away: How do diploid yeast cells transform themselves into haploid cells, so that they can mate and reproduce through meiosis? A young University of Oregon researcher named Ira Herskowitz proposed that a cassette of DNA dropped out, only to be replaced by a copy of another cassette of DNA, and that this event altered the very cell type. "It was such a simple yet beautiful solution," says yeast geneticist Brenda Andrews, University of Toronto. "And his drawings [known in the field as 'Iragrams'] were always just as beautiful." The cassette model of mating-type interaction (the image above was shown during Herskowitz' first presentation on the subject), has since become a pillar of modern yeast genetics.

--Sam Jaffe

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