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.

Transposition of Tc1 in Two Strains of Bristol

T. Starr, L.J. Harris, J.M. Babity, and A.M. Rose

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.