Activation of Sea Urchin Eggs by Inositol Phosphates is Independent of External Calcium
Overview
Authors
Affiliations
We investigated the contribution of external calcium ions to inositol phosphate-induced exocytosis in sea urchin eggs. We show that: (a) inositol phosphates activate eggs of the sea urchin species Lytechinus pictus and Lytechinus variegatus independently of external calcium ions; (b) the magnitude and duration of the inositol phosphate induced calcium changes are independent of external calcium; (c) in calcium-free seawater, increasing the volume of inositol trisphosphate solution injected decreased the extent of egg activation; (d) eggs in calcium-free sea water are more easily damaged by microinjection; microinjection of larger volumes increased leakage from eggs pre-loaded with fluorescent dye. We conclude that inositol phosphates do not require external calcium ions to activate sea urchin eggs. This is entirely consistent with their role as internal messengers at fertilization. The increased damage caused to eggs in calcium-free seawater injected with large volumes may allow the EGTA present in the seawater to enter the egg and chelate any calcium released by the inositol phosphates. This may explain the discrepancy between this and earlier reports.
Zebrafish Tric-b is required for skeletal development and bone cells differentiation.
Tonelli F, Leoni L, Daponte V, Gioia R, Cotti S, Fiedler I Front Endocrinol (Lausanne). 2023; 14:1002914.
PMID: 36755921 PMC: 9899828. DOI: 10.3389/fendo.2023.1002914.
The Role of Phospholipase D in Regulated Exocytosis.
Rogasevskaia T, Coorssen J J Biol Chem. 2015; 290(48):28683-96.
PMID: 26433011 PMC: 4661384. DOI: 10.1074/jbc.M115.681429.
Calcium pathway machinery at fertilization in echinoderms.
Ramos I, Wessel G Cell Calcium. 2012; 53(1):16-23.
PMID: 23218671 PMC: 4778076. DOI: 10.1016/j.ceca.2012.11.011.
Defining signal transduction by inositol phosphates.
Shears S, Ganapathi S, Gokhale N, Schenk T, Wang H, Weaver J Subcell Biochem. 2012; 59:389-412.
PMID: 22374098 PMC: 3925325. DOI: 10.1007/978-94-007-3015-1_13.
A new approach to the molecular analysis of docking, priming, and regulated membrane fusion.
Rogasevskaia T, Coorssen J J Chem Biol. 2012; 4(3):117-36.
PMID: 22315653 PMC: 3124629. DOI: 10.1007/s12154-011-0056-8.