The structural organization of actin in the sea urchin egg cortex will be investigated, concentrating on the analysis of changes in cortical organizaton associated with fertilization and cytokinesis, and the control mechanisms that regulate the organization of the cortical cytoskeleton. The long-term goal of these studies is a more complete understanding of the role of the cortical cytoskeleton in the events of early development, including fertilization, cytokinesis and morphogenesis.
Four specific aims are proposed. 1) The structural organization of the unfertilized egg cortex will be examined using rapid-freezing, freeze-fracture techniques. 2) The three-dimensional organization of actin in the fertilized egg cortex will be studied by the rapid-freeze, deep-etch method. 3) The role of cortical actin in the formation of the contractile ring will be studied by investigating: a) regional changes in cortical actin organization during cytokinesis, b) the relationship between cortical actin organization and contractile ring formation in eggs exposed to hyrostatic pressure, and c) the structurla organizaton of the contractile ring. 4) The role of cortical actin in microvillar formation will be studied by examining: a) microvillar formation and cortical actin reorganization at fertilization in eggs in which cortical granule exocytosis has been inhibited with hydrostatic pressure or NH4C1; b) the effect of inverting the sequence of Ca++ and pH changes at fertilizaton on the reorganization of the cortex; and c) the role of protein synthesis in the reformation of microvillar core filament bundles in eggs denuded of microvilli by high hydrostatic pressure. These studies will provide new information on the dynamics of cortical actin organization during early development and the role of cortical actin in fertilization and cytokinesis. In addition, they will contribute to a more complete understanding of the general mechanisms that regulate actin-based non-muscle cell motility. This information will aid in understanding the initiation and control of morphogenetic movements during normal embryonic development and the mechanism of tumor cell migration during metastasis.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM028307-05
Application #
3275612
Study Section
Cellular Biology and Physiology Subcommittee 1 (CBY)
Project Start
1980-07-01
Project End
1987-11-30
Budget Start
1985-12-01
Budget End
1986-11-30
Support Year
5
Fiscal Year
1986
Total Cost
Indirect Cost
Name
Harvard University
Department
Type
Schools of Medicine
DUNS #
082359691
City
Boston
State
MA
Country
United States
Zip Code
02115
Barton, N R; Bonder, E M; Fishkind, D J et al. (1992) A novel vesicle-associated protein (VAP-1) in sea urchin eggs containing multiple RNA-binding consensus sequences. J Cell Sci 103 ( Pt 3):797-809
Coleman, T R; Fishkind, D J; Mooseker, M S et al. (1989) Contributions of the beta-subunit to spectrin structure and function. Cell Motil Cytoskeleton 12:248-63
Bonder, E M; Fishkind, D J; Cotran, N M et al. (1989) The cortical actin-membrane cytoskeleton of unfertilized sea urchin eggs: analysis of the spatial organization and relationship of filamentous actin, nonfilamentous actin, and egg spectrin. Dev Biol 134:327-41
Henson, J H; Begg, D A (1988) Filamentous actin organization in the unfertilized sea urchin egg cortex. Dev Biol 127:338-48