Worm Breeder's Gazette 10(2): 30
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 previous issue of the gazette (WBG 10-1:70), R. P. and P. A. reported suppressor mutations that act in an allele-specific manner on a spontaneous mutation of unc-54. This mutation, r293, carries a deletion of about 250 bp in the 3' noncoding portion of the gene, that includes the AAUAAA sequence but does not appear to alter the coding region. The properties of the extragenic suppressors of r293 suggested that they might be members of the class of pleiotropic suppressors identified by reversion of certain alleles of tra-2 and lin-29 (J. H., A. Papp & V. Ambros, WBG 10-1:112). Complementation tests showed that three of the five complementation groups identified by r293 suppression correspond to the known morpho-mab suppressor genes mab-1, ll five classes of r293 suppressor exhibit the characteristic morphological abnormalities of male bursa and hermaphrodite vulva. The two new complementation groups were mapped to LGI and LGIII on the basis of this phenotype, and given the names mab-15 and mab-16. Both mab-15(r860) and mab-16( r896) are able to suppress the sensitive allele of tra-2, e1209. Conversely, mab-14(mal16), which was detected as a suppressor of lin- 29(n546) but not picked up in the r293 reversion, is able to suppress r293. The isolation table below suggests that mab-1 and mab-11 are frequent mutations (and they appear to be found at approximately gene knockout frequency), but the other four are represented only by rarer mutations. The nature of the r293 mutation may indicate that suppression by the morpho-mabs acts at the level of RNA rather than protein. Molecular analysis of unc-54 transcripts in r293 and its revertants should clarify the mechanism. It is likely that the morpho-mab suppression identifies a distinct class of allele in a variety of otherwise unrelated genes, in which case it may be a useful diagnostic tool. [See Figure 1]