[Single copy and repetitive DNA sequences of Echinodermata. I. Arrangement of DNA sequences of different multiplicity].

Arrangement of repetitive and single copy DNA sequences in the DNA of 8 Echinodermata species (sea urchins, starfishes and sea-cucumber) has been studied. Comparison of the reassociation kinetics of short and long DNA fragments assayed by hydroxyapatite binding indicates that the pattern of DNA sequence organization of all these species is similar to the so called Xenopus pattern found in genomes of most animals and plants. Interspecies differences consist mainly in the quantities of sequences of various repetition degrees and their interspersion with each other and with single copy sequences. Measurements of the size of S1 nuclease resistant reassociated repetitive sequences show variability in the relative quantities of long and short repetitive sequences of different species. Difference in the arrangement of single copy and repetitive sequences between Echinodermata species are not related to their evolutionary proximity.