Worm Breeder's Gazette 8(3): 92

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.

Panagrellus dysgenesis

C. Link, W.B. Wood

Crosses between some Panagrellus strains lead to unidirectional 
embryonic lethality and an increased mutation frequency.  (see 
previous Newsletter).  In the hope that these phenomea result from 
something akin to hybrid dysgenesis, we have isolated a repetitive 
element which is in several-fold higher copy number in the 'P' 
equivalent strain (CIS) than in the 'M' strain.  This was accomplished 
by screening a lambdaEMBL4 clone library prepared from the 'P' strain 
with probes of total genomic DNA from the 'P' and 'M' strains.  This 
repetitive element produces different Southern patterns when probed 
against the three Panagrellus strains we have tested, and is absent 
from C.  elegans.  The element is heterogeneous in size, with the 
largest (intact?) elements being roughly 2kb in size.  When DNA from 
one of the 'dysgenic' mutants is probed with the element, at least one 
band is found that is not in either parent.
Preliminary experiments suggest that we can isolate Panagrellus 
'twitcher' mutants similar to C.  elegans   
We are presently attempting to clone the Panagrellus unc-22 homologous 
region in hopes that we can 'catch' the postulated dysgenic element by 
generating twitcher mutants from the dysgenic cross.
A plasmid (p/4.0) containing the repetitive element has been 
microinjected into C.  elegans, and a strain has been obtained which 
contains an unstable (presumably extrachromosomal) large tandem array 
of the injected DNA.  Unexpectedly, worms carrying this array have a 
variable, low-penetrance (1-10%) tail defective phenotype.  Clones 
that no longer show the tail defect phenotype have been derived from 
array-containing worms; worms from these clones no longer contain the 
array.  Surprisingly, at least some of these no-tail defect clones 
appear to retain a unit-sized, unrearranged plasmid.