EXTRACTION OF DNA FROM MUCILAGINOUS TISSUES OF A SEA SLUG (ELYSIA-CHLOROTICA)

Efforts to study the cellular and molecular biology of the symbiotic a ssociation between opisthobranch molluscs and algal chloroplasts have been hampered by the copious amounts of mucus produced by the animals. We report for the first time a procedure for isolating total DNA free of contaminating mucilaginous compounds from the mollusc Elysia chlor otica Gould that harbors photosynthetically active chloroplasts from t he siphonaceous alga, Vaucheria litorea C. Agardh. This method involve s an initial extraction of fresh or freeze-dried Elysia tissue in abso lute ethanol and differential processing of the resultant two-phase pe llet. Final purification by CsCl-gradient centrifugation produces high molecular weight DNA suitable for molecular analysis.