Worm Breeder's Gazette 6(1): 24
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.
In the spermatogenesis mutant B245, spermatogenesis appears to be suppressed during growth at restrictive temperature, and normal oocytes appear at the developmental age at which sperm would be made. Pulse-up experiments on worms hatched within a one hour period show that the temperature sensitive period occurs between 6 and 16 hours post-hatching (25 C age). Pulse-down experiments show the same discrete time period during which worms are fertile if shifted to permissive temperature. This tsp occurs during the late L1-early L2 somatic gonad divisions. At a given age during the tsp, the fraction of sterile worms increases exponentially with increasing time at 25 C, with sterile worms appearing after as little as 15 minutes at high temperature. A 2-hour pulse was used to determine an age curve for the temperature sensitivity and gave a bell-shaped curve between 6 and 16 hours with a peak at 12 hours. Individual worms from such an experiment examined by Feulgen staining show three classes. Worms are either fertile (approximate 160 sperm per gonad arm), sterile (0 sperm per gonad arm); or semi-sterile (160 sperm in one gonad arm, and none in the other). Either gonad arm may be sterile, although the posterior arm is more sensitive at any time. Thus, the hermaphrodite spermatogenesis pathway seems to be controlled independently for each arm of the gonad during a short period close to the time of the L1 molt. Spontaneous B245 males have been isolated, although a fertile male stock has not been obtained. Him-5 B245 and him-1 B245 strains have also been constructed, and him-5 B245 males are fertile. Males of all three types show the same phenotype: at 16 C they produce sperm normally, but when shifted to 25 C, even as adults, they produce oocytes. Mature oocytes with typical premeiotic chromosomes are found by about 24 hours after the shift up, but so appear to degenerate. In males given ten hour pulses of high temperature, the switch to oocyte production will occur only for pulses beginning 15 hours post-hatching or later. This corresponds to the time when the hermaphrodite tsp ends. After such pulses, sperm production does not resume with the shift to permissive temperature. B245 maps to linkage group III, approximately 7 map units from dpy-1. It complements tra-1 giving fertile heterozygous hermaphrodites at 25 C.