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Heterogeneous distribution of “lysosomal” hydrolases in yolk platelets isolated from unfertilized sea urchin eggs by zonal centrifugation

1975; Elsevier BV; Volume: 46; Issue: 2 Linguagem: Inglês

10.1016/0012-1606(75)90116-5

1095-564X

Herbert Schuel, Walter L. Wilson, Jean R. Wilson, Robert S. Bressler,

Aquatic life and conservation

Three typical “lysosomal” glycosidases, α-L-fucosidase, N-acetyl glucosaminidase and N-acetyl galactosaminidase, were localized within the yolk platelets of unfertilized Strongylocentrotus purpuratus eggs. Homogenates of eggs were fractionated by rate-zonal centrifugation, and the isolated particles were subjected to integrated biochemical and morphological (electron microscopic) analysis. Enzymatic markers were used to determine the distribution of mitochondria (cytochrome oxidase), yolk platelets (acid nitrophenyl phosphatase), and cortical granules (β-1,3 glucanase) in the sucrose density gradient. Yolk platelets were isolated in a high state of purity, with contamination by mitochondria and cortical granules at trace levels. Enzymatic heterogeneity exists within the yolk platelet population. Acid nitrophenyl phosphatase and α-l-fucosidase activities appear to be uniformly distributed within all the yolk platelets, while N-acetyl glucosaminidase and galactosaminidase activities appear to be preferentially distributed within the slower sedimenting sub-population of yolk platelets. Another band of hexosaminidase containing particles sedimented slightly slower than the bulk of the yolk platelets, coincident with the mitochondria. The acid hydrolases packaged in the yolk platelets may participate in the mobilization of yolk material after fertilization. The yolk platelet thus appears to be a highly complex and structured “lysosome-like” storage organelle.