Worm Breeder's Gazette 8(3): 88
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 some preliminary results from our attempts to identify mRNA from unc-22. Probing Northerns with various lambda clones from the unc-22 region reveals 2 transcripts. One is about 1.6kb in size and hybridizes only to our left-most clone, which only partially spans the region defined by the insertions. We assume this message is the product of a gene adjacent to unc-22. A second transcript that hybridizes to the entire set of clones spanning the insertion sites is very large--much larger in fact, than the 6.1kb unc-54 mRNA. The message is somewhat degraded but we do see a definite band. It is present in RNA prepared from mixed cultures and is at roughly 2-10% of the level of unc-54 message. Our reasons for believing that this large transcript is the product of unc-22 are threefold: (1) Tc1 insertions over a 20kb distance can disrupt unc-22 function, which is at least consistent with the large message seen. (2) We have also compared message levels for this presumed unc-22 transcript in N2 and unc-22(s32), an amber allele, and the s32 signal is greatly reduced relative to the signal from N2 (see Brown et al., Gene 20:139-144, 1982). (3) Finally, we have used single-stranded M13 clones of opposite orientation from the central region of unc-22 to probe Northerns of N2 and s32 RNA. One M13 clone hybridizes strongly to the large transcript from N2 but only weakly to RNA from s32, while the probe of opposite orientation does not hybridize to anything in either lane. From this last result we predict that unc-22 is transcribed from right to left on the genetic map. (This is a reversal from what we said at the 1984 GSA meeting). Recent sequencing results show that this direction yields the only continuous open reading frame. A preliminary computer search of DNA and protein sequence libraries using this open reading frame sequence did not reveal any homologous sequences to unc-22.