title: Cytoskeleton of the unfertilized sea urchin egg.
abstract: Unfertilized Paracentrotus lividus egg cytoskeleton is prepared by mild, nonionic detergent extraction at 4 degrees C in buffer systems containing either 2-methyl-2,4-pentanediol (hexylene glycol) or glycerol. These extractions allow the isolation of cytomatrices that maintain the egg form and are 70-80 micron in diameter. DNase inhibition assays show that actin is in polymerized form in these cytomatrices. Ultrastructural observations reveal that the cytoskeletons are made up essentially of 2 categories of filaments, 7-8-nm and 2-4-nm in diameter, respectively. After heavy meromyosin labelling, short, radiating actin filaments are seen in the cortical region, while longer actin filaments are found in the internal region of these cytomatrices. The 2-4-nm filaments of still unknown biochemical nature are organized in a meshwork. In contrast to results found with fertilized eggs, bundles of actin filaments and microtubules are absent; 8-13-nm filaments are not detected.
mesh_terms: D000199:Actins / Q000032:analysis; D000818:Animals; D003599:Cytoskeleton / Q000648:ultrastructure*; D005260:Female; D008854:Microscopy, Electron; D010063:Ovum / Q000166:cytology / Q000648:ultrastructure*; D012617:Sea Urchins
chemical_list: D000199:Actins