Gilles Foucault1, Marie‐Noëlle Raymond1, J. Pudles1
1Laboratoire de Structure et Réactivité des Protéines C.N.R.S., U.A. 1131, Université Paris XI, Orsay, France.
Tóm tắt
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.
