Worm Breeder's Gazette 9(2): 44
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 order to identify Tc1 polymorphisms close to the sex-determining gene tra-1 III, congenic strains carrying the interval vab-7 - dpy-18 ( markers that flank tra-1) from several different high copy number strains have been constructed. The first of these, using the Bergerac strain N62, revealed several polymorphisms mapping between tra-1 and dpy-18 (see WBG 8-1: 45). However, neither of the strains DH424 and TR403 appear to contain any extra Tc1 sites in the vab-7 - dpy-18 interval. Also, unique probes derived from the two of the N62 polymorphisms were used to show that the N62 insertion sites are vacant in another Bergerac strain, RW7000. Thus, different high copy number strains may have markedly different Tc1 patterns in a given interval. Carol Trent reported at the 1985 C. elegans Meeting that a strain carrying Sma-1(e30), derived from N2 by Sydney Brenner, had considerably more than thirty copies of Tc1 (the normal N2 number). The Cambridge working stock of Sma-1(e30) (designated CB4000) has been grown continuously at 15 C for more than fifteen years, by a succession of workers at the MRC. DNA from this stock was compared with DNA from the oldest available stock of e30 (designated CB30, formerly E30), which has been stored frozen since approximately 1969. CB30, which is the ancestor of CB4000, has a Tc1 pattern (EcoRI digest) identical to N2, but CB4000 has many more copies of Tc1 (more than 100, i.e. a smear resembling that seen with DH424 or TR403). The CB4000 strain differs from CB30 in other ways: it grows poorly and has a slightly different small phenotype, males are unable to mate, the strain is slightly Him, and it has a mutator activity (twitchers and other mutants are occasionally segregated). Therefore it seems that a Tc1 mobilization event took place at some point during the maintenance of e30 as a 15 C stock, before 1975 but after the original stock, CB30, had been frozen. So, who was Prince Charming, and how did he wake up Sleeping Beauty?