Worm Breeder's Gazette 8(2): 16
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.
Arguments that dysgenic elements are 'selfish DNA' which propagate in a population by colonizing virgin genomes via sex (1) suggest that such elements may be uncommon in self-fertilizing species. We have therefore undertaken to look for dysgenesis and/or dysgenic elements in male/female rhabditid species. We have obtained Panagrellus redivivus strains from R. Pulak, Manitoba (RP strain); P. Sternberg, MIT (PS strain); and the stock center (SC strain). Matings between these strains reveal a dramatic unidirectional effect: the brood size of RP male x PS female is less than 1/20th of that seen in the reciprocal cross or in intrastrain crosses of either parent. The 'missing' progeny from the anomalous cross appear to result from embryonic lethality, since the gravid PS females contain degenerating embryos. The few progeny which escape this lethality are generally healthy and behave like an RP strain in subsequent backcrosses. (The SC strain behaves like RP in these crosses.) Two recessive mutants (1 Unc, 1 Dpy) have been recovered as F3's from RP male x PS female crosses; the frequency at which these mutants were recovered seems to indicate a mutation frequency higher than the spontaneous rate. These observations differ from Drosophila dysgenesis in that lethality is observed in the first generation. This could be accounted for if dysgenic elements are mobile in both somatic and germline cells in the embryo. We are looking for such an element by screening a genomic RP clone library with total genomic RP and PS DNA's, which should enable us to find clones which contain repetitive elements that differ in copy number between these strains. We would be interested in obtaining other Panagrellus strains or any wild male/female C. elegans-like strain. In the course of this work we have generated a C. elegans N2 clone bank in lambda EMBL/4, which has advantages over lambda1059(2) and may be useful to someone.