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 Elements, Candidates for an Adequate Transposon Tagging System in C. elegans

Yves de Chastonay, Christopher Link, Fritz Mller and Heinz Tobler

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.