Worm Breeder's Gazette 9(2): 63
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 have continued our study of mutations affecting the long range embryonic migrations of the neurons CAN, HSN and ALM (see 1985 C. elegans Meeting Abstracts, p. 18). To date we have studied six mutations that define five loci and can be divided into two phenotypic classes (see table below). In Class-1 mutants [mig(ct41) III and mig- 2(rh17) X], the CAN, HSN, and ALM migrations are all partially defective with high penetrance. In Class-2 mutants [vab-8(e1017 and ct33) V, mig(ct73) V, and mig(7a) III], CAN migration is defective with high penetrance whereas defects in HSN and ALM migrations with much lower penetrance vary among the mutants as shown in the table. mig(ct73) V and mig(7a) III are recently acquired mutants. mig(ct73) V was isolated by us as a spontaneous mutant that appeared on an N2 stock plate. mig(7a) III was isolated by Eve Wolinsky (MIT). Both mutants were recognized by their skinny tails, a phenotype attributed to CAN misplacement in vab-8 animals (Sulston and Hodgkin, WBG vol. 5. , No. 1, p.19). mig(ct73) V complements vab-8(e1017) V, and mig(7a) III complements mig(ct41) III. CAN migration is less severely affected in mig(ct73) V and mig(7a) III than it is in vab-8 V. In most vab-8 animals, CAN migration is apparently completely abolished: the CAN nucleus is found over the nerve ring in the head (Sulston and Hodgkin, loc. cit.; B. Stern, 1985 C. elegans Meeting Abstracts). In most mig(ct73) V and mig(7a) III L1's, CAN is seen partway between its position of birth and its normal postembryonic position (Nomarski optics). Three double mutants have been constructed, characterized, and found to show additive effects of the two mutations. Double mutants carrying either of the Class-1 mutations mig(ct41) III or mig- 2(rh17) X and a vab-8 mutation appear to exhibit completely defective CAN migration, while HSN and ALM migrations are partially defective with high penetrance. A double mutant carrying both of the Class-1 mutations, like mutants, exhibits partially defective CAN, HSN, and ALM migrations, but these nuclei tend to remain closer to their positions of birth in the double mutant. [See Figure 1]