Worm Breeder's Gazette 9(2): 43
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.
An altered Tc1 hybridization pattern using the restriction enzymes EcoRI and HindIII in the N2 strain BC313 (Rec-1) was reported by Rattray and Rose in the last Newsletter. Several explanations for the altered band pattern were suggested: EMS mutagenesis, conversion events involving Tc1(Eco) and Tc1(Hin), or Tc1 mobility. We have examined 14 N2 strains carrying EMS-induced mutations. Of these, only the Rec-1 progenitor strain, CB51 (Unc-13), showed an altered hybridization pattern. In addition, the Tc1 pattern of BC313 was found to differ from N2 with 11 different enzymes. Subsequent comparison of BC313 with CB51 also showed different Tc1 patterns with each enzyme tested. These observations suggest that it is unlikely that the altered Tc1 pattern was the result of EMS mutagenesis or gene conversion events. The transposition of Tc1 in the genome would be expected to produce DNA rearrangements. We have isolated 18 different Tc1s and their unique flanking DNA from wild type N2 to search for such rearrangements. After removal of the Tc1 by EcoRV digestion, the remaining single copy DNA was used to probe Southern blots containing N2, BC313, and CB51 DNA. Of the 9 probes tested to date, one probe showed an additional band in the CB51 strain. We are investigating the nature of this DNA modification as well as continuing to search for other rearrangements. Although other explanations have not been ruled out, we favor the hypothesis that Tc1 has undergone a small number of transposition events in these two strains.