Worm Breeder's Gazette 11(4): 32
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.
PAT, a transposable element of Panagrellus redivivus, was identified after its insertion and thus the creation of a spontaneous mutation in the Unc-22 gene of the nematode. Copy numbers per haploid genome range from 10 to 50, depending on Panagrellus strains, and the distribution of PAT elements is rather scattered. The predominant and presumably autonomous form is about 5.6 kb long, but several internally deleted elements are also detected in the genomes. The deletions analyzed are all confined to one and the same half of the element and do not comprise repeated element sequences. Direct repeat (DR) arrangement is not as in typical retroids. Rather, an integral DR is found inside, while opposed DR halves are found to flank the elements. Organization with respect to half DRs (A and B) is alternate (A...BA..B), implying that PAT elements were not created by the insertion of separate elements into or next to one another. This DR arrangement seems to be conserved in most PAT elements. Moreover, internal PAT domains are always associated with DR sequences while the latter seem to also pre-exist as solo DRs in the genome. No exact target site duplication was found flanking the elements for which the borders were sequenced, however, a possible insertion site specificity can be deduced (i.e., A..AC). Northern blot hybridization does not indicate the presence of full length transcripts, rather excluding a retroid mode of transposition. Merely one transcript of about 900nt length is detected on blots having 10 g total RNA per track. Furthermore, the transcript maps to the preferentially deleted region of PAT elements. Within reasonable limits of speculation, this transcript could code for a transposase- like protein, unless the factors necessary for transposition were to be provided in trans. The deleted forms might therefore well depend on full length elements for transposition. Cross-hybridization to C. elegans as well as to A. Iumbricoides genomic DNA turned out to be negative under high stringency conditions. Hence, deleterious elements in combination with putatively autonomous full length elements, merely lacking border sequences, could be interesting candidates for a 'jump-starter/mutator' transposon tagging system, to be injected in the closely related nematode C. elegans.