POLYPLOIDS AND SEX DETERMINATION IN CAENORHABDITIS ELEGANS

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Abstract
Tetraploid stocks of Caenorhabditis elegans var. Bristol carrying autosomal and X-linked markers have been produced. Tetraploid hermaphrodites fall into two categories: those that give about 1% male self-progeny and those that give 25 to 40% male self-progeny, The former are basically 4A;4X—four sets of autosomes and four sex chromosomes—and the latter are 4A;3X. Males are 4A;2X. (Diploid hermaphrodites are 2A;2X; males are 2A;IX.) Triploids wsre produced by crossing tetraploid hermaphrodites and diploid males. Triploids of composition 3A;3X are hermaphrodites; 3A;2X animals are fertile males. Different X-chromosome duplications were added to a 3A;2X chromosome constitution to increase the X-to-autosome ratio. Based on the resulting sexual phenotypes, we conclude that there exists on the C. elegans X chromosome at least three (and perhaps many mare) dose-sensitive sites that act cumulatively in determining sex.