A related moderately repetitive DNA family in the nematodes Ascaris lumbricoides and Panagrellus silusiae

Digestion of genomic DNA from the nematodes Panagrellus silusiae and Ascaris lumbricoides with restriction endonuclease BamH1 releases a 0.7 kilobase (kb) fragment. The 0.7 kb fragment from both nematodes was cloned onto E. coli plasmid pUC19. Using representative clones as DNA hybridization probes, it was found that (i) the BamH1 fragments cross-hybridize; (ii) a ladder-effect with multiples of 0.7 kb was evident in both species after hybridization to genomic DNA and (iii) the genomic copy number of BamH1 elements is 150 and 195 for P. silusiae and A. lumbricoides respectively. DNA sequence analysis of the inserts, AL700-1 and PS700-1, revealed nucleotide blocks with over 85% similarity. No open reading frames are present in either DNA fragment. Neither fragment hybridizes to genomic DNA from Caenorhabditis elegans. Northern blot hybridization indicated that the 0.7 kb element is transcribed into poly(A)(-)-RNA in P. silusiae; but, is not transcribed in adult Ascaris muscle. Thus, P. silusiae and A. lumbricoides share a homologous, tandemly arrayed, moderately repetitive DNA family.