ACTIN ORGANIZATION IN THE SEA-URCHIN EGG CORTEX

The molecular basis of the cortical changes in actin that occur on fertilization remains to be elucidated. The discovery of two distinct assembly states of actin in the prefertilization cortex and the purification of numerous actin-associated proteins that are likely to regulate these cortical changes provide appropriate materials for future studies. One problem has been the difficulty in properly fixing the rather large sea urchin eggs for localization studies. The applications of cryofixation techniques and Lowicryl embedding methods, however, now allow the localization of the various actin-associated proteins as a function of time after fertilization. Such structural studies should provide important clues regarding the possible involvement of these proteins in the fertilization-induced changes in actin organization in the sea urchin egg cortex. © 1992 Academic Press, Inc.