Isolation of heavy satellite deoxyribonucleic acid from sea-urchin spermatozoa

Two different methods were used to isolate high-molecular-weight heavy satellite DNA from the spermatozoa of the sea-urchin Lytechinus variegratus. Purification of satellite rDNA (ribosomal DNA) by selective denaturation of the spermatozoal DNA followed by a separation of the native and denatured DNA in an aqueous mixture of poly(ethylene glycol)/dextran is affected by the molecular weight of the spermatozoal DNA. Enrichment of satellite rDNA by selective precipitation of main-band DNA by poly-L-lysine is cumbersome but more suitable.