THE SUBCELLULAR DISTRIBUTIONS OF SOME HYDROLYTIC ENZYMES IN UNFERTILIZED EGGS OF THE SEA URCHIN, ARBACIA PUNCTULATA

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Abstract
Differential centrifugation and density gradient centrifuga-tion were applied to nuclei-free homogenates of unfertilized eggs and adult gut of the sea urchin, Arbacia punctulata. to determine the distributions of several hydrolytic enzymes and of nucleic acid and protein. Two types of large, visible granules were partially separated from egg homogenates. The first type is rich in acid phosphatase and esterase; the second is rich in sulfatase, RNAase and nucleic acid. Neither of these granule fractions is associated with the mitochondrial fraction. Acid phosphatase activity was also found to be high in a fraction containing the echinochrome granules; these could be separated from the acid phosphatase granules described above. The activities of the above enzymes were also determined in microsomal and soluble fractions of the egg, and the distribution of phosphatase and esterase were also determined in the major sub-cellular fractions of adult gut. The microsomal and soluble fractions contain high activities of the enzymes in question. The major difference between eggs and gut tissue is that large granules containing the enzymes are present in eggs but not in the gut tissue.