Worm Breeder's Gazette 10(1): 94
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.
Temperature-sensitive maternal mutations in the emb-1 gene cause defects in the migration and fusion of pronuclei and in the pseudocleavage of a fertilized egg. The gene function is required within a short period around fertilization. We are isolating and characterizing revertants of emb-1 mutations to investigate emb-1 gene function and to analyze events around fertilization. With EMS mutagenesis we have independently isolated 4 revertants from emb-1( hc57) III, which can grow at the nonpermissive temperature of 25 C. Two of them were shown to be dominant mutations and mapped to linkage group I and II. Two others were semidominant and mapped to linkage group III. The former two revertants were further characterized to show that maternal expression of the mutations was necessary and sufficient for the suppression of emb-1(hc57). Cytological observation has revealed that these revertants in the hc57 background exhibited weak pseudocleavage and lacked male pronuclear migration at 25 C. This suggests that the restoration of the emb-1 gene function is incomplete and that normal pseudocleavage and male pronuclear migration are not absolutely necessary for the development of C. elegans. DAPI staining of the hc57 mutant detected more stained materials in the female pronucleus than in the male pronucleus and no polar bodies in fertilized eggs. With rhodamine-phalloidin staining, we found that the hc57 mutant exhibited rapid aggregation of microfilaments after fertilization at 25 C we are looking into a possible defect in meiosis after fertilization.