Worm Breeder's Gazette 5(1): 18a
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
We are investigating somatic loss of X-chromosomes as a means of producing mosaic worms at relatively high frequencies. We produce worms heterozygous for the X-linked muscle morphology mutant, unc-78( e1217), which are homozygous for various him's. Only one such mutant, him-2(e1065), generates spontaneous mosaics at a frequency greater than 0.1%. We are still examining two other lines and are exploring other means of inducing high-frequencies of X-linked mosaics . We have observed loss of X-chromosomes from worms irradiated by X- rays from 137Cs. The loss is seen in the F2 of irradiated worms (or the F1 or irradiated embryos). The number of males in this generation is in the range of 4-10%. The frequency of males is not distributed according to a Poisson but rather shows 'jack-pots' as might be expected from events that hit individual X chromosomes. The frequency of males in a jackpot can be as high as 40%. Most hermaphrodite siblings of these males are normal and show no increase in the frequency of male progeny. We asked whether only the irradiated chromosome was lost in an animal heterozygous for a marked irradiated X-chromosome and an unmarked unirradiated X-chromosome. Hermaphrodites marked with the X- linked marker, unc-78, were irradiated and then mated to N2 males. Wild type progeny were picked, cloned and scored for male offspring. Both wild type and unc-78 males were found at approximately equal frequency; apparently either chromosome can be lost.