17Echinochrome A, an active inhibitor of lipid peroxidation, was found to appear and accumulate in developing sea urchin embryos. Complex mutual effects of various components of extracts from sea urchin embryos were noted to take place with methyl oleate peroxidation. These effects may reveal the functional role of naphthoquinones in sea urchins. sea urchin eggs; embryos; echinochrome A; antioxidative action INTRODUCTION In addition to carotenoids and melanin, which are widespread in the animal kingdom, sea urchins produce polyhydroxynaphthoquinones, a group of pigments uncommon to animals. Echinochrome A (EA), first detected by MacMunn [ 1] in perivisceral fluid of the sea urchin, Echinus esculentus, has attracted maximum attention of biologists and chemists. Later, naphthoquinones were extracted from sea urchin tests and spines and were termed spinochromes after their place of origin. In some sea urchin species, polyhydroxynaphthoquinones are contained in oocytes [2], and in others appear de novo in embryos, preferentially when the gastrula transforms into the pluteus [3].Thus, sea urchins have a need for these substances already in the early stages of development, and naphthoquinones presumably take part in major physiological processes. Several hypotheses have been suggested regarding the functions of these substances in animals; however, none of them has thus far been duly confirmed experimentally [ 4].For the first time, we have established EA to be a highly active inhibitor of fat peroxidation [ 5]. This EA property is indicative of its probable involvement in controlling redox processes in animals in general, and lipid peroxidation in particular. This makes possible a new approach in elucidating the biological function of naphthoquinones, specific components of echinoderms.We therefore attempted to assess the possible antioxidative action of EA 0165-1269/81/0000----Q000/$02.50 18 in early stages of sea urchin development and its interaction with other antioxidants within the embryos (a-tocopherol).
MATERIALS AND METHODSThe common sea urchin, Strongylocentrotus nudus Agassis and the sand dollars, Scaphechinus mirabilis (Agassis) and Echinorachnius parma (Lamarck) were used as experimental objects.The specimens were collected in Posiet Bay, Sea of Japan, in August during intense spawning. Fertilized and washed eggs were incubated in filtered sea water at 18°C with continuous agitation. The samples were taken at different stages of embryo development, including late pluteus.Centrifuged eggs or embryo samples were weighed and homogenized with chloroform/methanol after Bligh and Dyer [ 6]. Following careful separation of lipid extracts, the chloroform-washed residues were extracted with a mixture of ethanol and concentrated hydrochloric acid (1 : 1, by vol.) and, after retention for 1 h, were filtered and washed with the same mixture. The resultant extracts were diluted with water, and the pigments extracted with chloroform. The lipid and pigment extracts were separately evaporated in vacuo and transferred to ...
