The P.I. proposes to explore the role of steady free cytosolic calcium ion gradients in establishing pattern during early development. Such gradients have never been directly demonstrated. Nevertheless, a slowly growing but substantial body of indirect evidence indicates both their existence, their direction and their significance; while recent technical advances should now make it possible to directly detect and measure such gradients. The methods which are proposed to accomplish this involve the use of chemically modified aequorins and a so-called imaging photon detector as well as a conventional photon counting system. The living systems proposed for their exploration include the fucoid (brown algal) egg, the medaka fish egg, the sea urchin egg, the ascidian egg and the cellular slime mold, Dictyostelium. Where gradients can be measured, their developmental role will then be explored. This will be done by means intended to modify (or even suppress) calcium gradients and/or developmental pattern. These means will include the use of calcium buffer injections and imposed calcium ionophore gradients as well as lithium ions and other pattern-modifying agents as well as pattern mutants. The fundamental insights that may be gained in these studies should ultimately relate to those aspects of health which depend upon growth and development.
| Speksnijder, J E (1992) The repetitive calcium waves in the fertilized ascidian egg are initiated near the vegetal pole by a cortical pacemaker. Dev Biol 153:259-71 |
| Speksnijder, J E; Sardet, C; Jaffe, L F (1990) Periodic calcium waves cross ascidian eggs after fertilization. Dev Biol 142:246-9 |
| Speksnijder, J E; Sardet, C; Jaffe, L F (1990) The activation wave of calcium in the ascidian egg and its role in ooplasmic segregation. J Cell Biol 110:1589-98 |
| Speksnijder, J E; Corson, D W; Sardet, C et al. (1989) Free calcium pulses following fertilization in the ascidian egg. Dev Biol 135:182-90 |
