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.
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.