PIGMENTATION IN THE ORANGE TUNICATE, ECTEINASCIDIA TURBINATA.

Some chemical properties of the orange pigment from eggs and embryos and the mantle tissue of adult Ecteinascidia turbinata, as well as ultrastructural characteristics of pigment masses in the mantle, have been examined. The diffuse egg and embryo pigment has solubility and absorbence characteristics of carotenoids, which are solubilized within yolk platelets. The granular mantle pigment, however, is not carotenoid. It is soluble only in organic-aqueous systems, stable to boiling and gross changes in pH, and absorbs strongly in the UV region with a single major peak at 360 nm. Mantle pigment is found in pigment bodies which ultrastructurally are composed of apparently straight and continuous tubular subunits, approximately 500 to 600 Å in diameter, and oriented parallel to the long axis of the body. The pigment bodies are not localized in obvious cells but found within large areas of fibrillar material that are bound by cytoplasmic membranes and occasionally contain an apparently degenerate nucleus. It may be that mantle pigment is derived from pigment cells of the blood which lose their typical cellular appearance as they become permanent features of the mantle tissue.