Worm Breeder's Gazette 9(2): 77
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.
sot-1 (e2123) ('sore-throat') is a zygotic embryonic lethal mutation preventing differentiation of the pharynx. At 25 C, e2123 embryos arrest at the pretzel stage and fail to form a functional pharynx. Pharyngeal cells are formed and are surrounded by a basement membrane. The only defects outside of the pharynx detected by Nomarski microscopy are lumps and dumpiness in the head, possibly caused by improper pharyngeal differentiation. Some mutant embryos hatch and die as L1's. Immunofluorescence with monoclonal antibodies shows that pharyngeal differentiation arrests at the plum to twofold stage (e.g. no expression of pharynx-specific myosin), whereas differentiation outside of the pharynx appears to proceed as in wild type embryos. sot-1 maps to a locus on LGIII between vab-7 and tra-1. It is a zygotic embryonic lethal, completely penetrant at 20 C and 25 C, wild type at 15 C. The ts period is near the end of proliferation/early morphogenesis in the embryo. Further evidence for a pharynx-specific differentiation function comes from the phenotypes of e2123/eDf2 and e1855 embryos. eDf2 is a large deficiency including sot-1. e1855 ( obtained from J. Hodgkin) fails to complement tra-1 and e2123 and is probably a small deficiency. The phenotypes of both e2123/eDf2 and e1855 embryos are very similar to that of e2123, however, the phenotype of e1855 embryos is slightly less severe than that of e2123. Also, recombination was observed between e2123 and e1855. This suggests either that e1855 has a breakpoint within sot-1, retaining some sot-1 activity, or that the failure of e1855 to complement e2123 may be due to a position effect. Attempts to obtain new alleles and to define the null phenotype are in progress.