Worm Breeder's Gazette 9(2): 34

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.

Evidence for a Second Transposon in C. elegans

A. Levitt and S. Emmons

At the last worm meeting we reported the finding of a repetitive 
element in C.  elegans that had strain number differences reminiscent 
of those found for the transposon Tc1.  This new element was found in 
an experiment in which we looked for larger variants of Tc1, hoping to 
find a sequence that might be to Tc1 what the autonomous Ac element is 
to the non-autonomous Ds element in maize.
Subsequent experiments in which we cloned several of the elements 
from Bergerac and Bristol phage libraries suggested that this is not 
the case.  The new element, tentatively named Tc2, is not physically 
associated with Tc1 except in the single case in which we picked it up.
Restriction maps of five of the members of the family do not reveal 
any simple pattern among them; e.g., they do not appear to be simple 
deletion variants of one 'master' form.
We are currently pursuing a line of evidence which may enable us to 
prove conclusively that Tc2 is actively transposing in the germline of 
Bristol/Bergerac recombinants.  A number of such recombinants were 
kindly sent to us by Ikue Mori and Don Moerman in Robert Waterston's 
lab at Washington University.  These recombinants have either retained 
or lost a single well-mapped locus which confers germline 
transposition activity on Tc1 (as assayed by reversion of unc-22(
st136::Tc1)).  While doing Southern blot experiments to see if Tc1 
activity correlates with a member of the Tc2 family, we noticed three 
cases in which recombinant strains contained Tc2 bands which are not 
present in either Bergerac or Bristol.  It is possible that these 
bands represent new insertions into germline DNA.
We are now cloning one of these bands in hopes of isolating an 
active version of Tc2.  We will demonstrate that it is a new insertion 
(if it is) by using its flanking sequence to pull out its empty site 
from a parent strain.