Worm Breeder's Gazette 11(4): 36
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.
emb-5 is a maternally expressed gene and is required for achieving the correct timing of E cell division at gastruIation. The second E cell division occurs prematurely at the 26-cell temperature-sensitive emb-5 mutants, while in the wiId-type it takes place at the 44-cell stage (1, 2). As previously reported (WBG 11/1:39), we have identified the two Tc1s linked to the emb-5 gene in Bergerac BO. The genomic phage clones isolated by Tc1 flanking probes have been assigned on the physical map by Drs. J. Sulston and A. Coulson and found to be separated by about 400 kb. Based on both genetic and physical map data, we estimated that one of the two Tc1s is about 40 kb or one cosmid length to the right of emb-5.We have succeeded in transforming the ts emb-5 mutant hc61 first by injecting a mixture of three cosmids, C16B3, C38D4, and W05E6 and then by a single C38D4 cosmid (Figure 1). Transformants were usually sick but still produced a few viable embryos at nonpermissive temperature. So far the search for RFLPs in emb-5 mutants and putative intragenic revertants of hc61 with C38D4 as a probe has not been successful. Probably, these strains have small polymorphisms or point mutations. There are at least 8 different mRNAs transcribed from the C38D4 genomic region. However, we observed no differences in size or amount of any of these transcripts between the wild-type and the mutants tested. We are trying to rescue hc61 with DNAs subcloned from C38D4 and are also engaged in research to identify mutation sites. [See Figure 1]