[Genome of the pogonophore Siboglinum fiordicum: organizational characteristics and divergence with respect to the genomes of representatives of certain types of invertebrates].

DNA of Pogonophora Siboglinum fiordicum was studied. DNA was isolated from ethanol fixed animals. It contains 40.5% GC according to the melting temperature and 39.3% GC as estimated by cation-exchange chromatography. From the reassociation kinetic data with a [125I] tracer 400 nucleotide long it is clear that 70% of the genome consists of repetitive sequences. The fast component (C0t less than 0.04) constitutes 11% of the genome, the intermediate (C0t 1/2 = 1.5, repetition frequency 1600)--59%. The unique sequences comprise about 30% of the genome. Experiments where [125I]tracers of increasing length were reassociated with driver DNA fragments 300 nucleotides long point out that at least 80% of the genome contains repetitive sequences, part of them being organized in short-period interspersion patterns. The hybridization of Pogonophora [125I]DNA fragments with DNA of invertebrates of other types--Echinodermata, Ascidia, Mollusca, Annelida--did not show any measurable homology between their DNAs neither in repetitive, nor in the unique fraction.