Worm Breeder's Gazette 7(1): 51

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.

Is the Bergerac/Bristol DNA Polymorphism a Transposon?

B. Rosenzweig, L. Liao, D. Hirsh

C.  elegans var.  Bergerac worms contain 1.7 kb of DNA adjacent to 
actin gene III that var.  Bristol worms do not.  This DNA polymorphism 
has been used as a phenotypic marker for mapping the cluster of actin 
genes I, II and III.  We were interested to know more about this 1.7 
kb of DNA.  Other polymorphisms that were also 1.7 kb larger in 
Bergerac appeared after hybridization to randomly cloned fragments of 
Bristol DNA (Emmons et al., PNAS 76, 1333 (1979)).
A DNA fragment containing the 1.7 kb insert was cloned from a lambda 
Charon-10 Bergerac recombinant DNA library.  This clone hybridized 
strongly to about 50 bands in a whole genome blot of Bergerac DNA.  
The clone hybridized less strongly to Bristol DNA and hybridization 
was to a different set of about 30 bands.
Subfragments of the cloned Bergerac DNA were used as hybridization 
probes against each other and revealed that the 1.7 kb insert is 
terminally repetitious.  The end subfragments did not hybridize to the 
middle subfragment.  The end and middle subfragments gave the same 
patterns when hybridized to whole genome blots of Bergerac and Bristol 
DNA's.  The cloned Bergerac DNA was denatured, quick-cooled and 
examined in the EM and it revealed a single-strand 1.5 kb loop with a 
double-strand stem of about 75 bp.  Therefore, the terminally 
repetitious ends contain inverted sequences.
We hybridized the 1.7 kb DNA to blots of DNAs from worms from the 
Hirsh, Ward, Riddle labs and from the stock center.  All had the same 
patterns.  Two different patterns were found after hybridization to 
the wild strains PA-1 and C12A (from Carl Johnson) but no differences 
were seen with GA-l (from Carl Johnson's backyard).  We don't know if 
this is a transposon but it seems like one.  We also don't know if 
it's transcribed.