scholarly journals Inositol trisphosphate induces calcium release from nonmitochondrial stores i sea urchin egg homogenates.

1985 ◽  
Vol 260 (26) ◽  
pp. 13947-13954 ◽  
Author(s):  
D L Clapper ◽  
H C Lee
Keyword(s):  
Sea Urchin ◽  
Calcium Release ◽  
Inositol Trisphosphate ◽  
Sea Urchin Egg

scholarly journals The part played by inositol trisphosphate and calcium in the propagation of the fertilization wave in sea urchin eggs.

1986 ◽  
Vol 103 (6) ◽  
pp. 2333-2342 ◽  
Author(s):  
K Swann ◽  
M Whitaker
Keyword(s):  
Sea Urchin ◽  
Calcium Ions ◽  
Calcium Concentration ◽  
Calcium Release ◽  
Inositol Trisphosphate ◽  
Lytechinus Pictus ◽  
Sea Urchin Egg ◽  
Sperm Entry ◽  
Fertilization Membrane

Sea urchin egg activation at fertilization is progressive, beginning at the point of sperm entry and moving across the egg with a velocity of 5 microns/s. This activation wave (Kacser, H., 1955, J. Exp. Biol., 32:451-467) has been suggested to be the result of a progressive release of calcium from a store within the egg cytoplasm (Jaffe, L. F., 1983, Dev. Biol., 99:265-276). The progressive release of calcium may be due to the production of inositol trisphosphate (InsP3), a second messenger. We show here that a wave of calcium release crosses the Lytechinus pictus egg; the peak of the wave travels with a velocity of 5 microns/s; microinjection of InsP3 causes the release of calcium within the egg; calcium release (as judged by fertilization envelope elevation) is abolished by prior injection of the calcium chelator EGTA; neomycin, an inhibitor of InsP3 production, does not prevent the release of calcium in response to InsP3 but does abolish the wave of calcium release; the egg cytoplasm rapidly buffers microinjected calcium; the calcium concentration required to cause fertilization membrane elevation when microinjected is very similar to that required to stimulate the production of InsP3 in vitro; and the progressive fertilization membrane elevation seen after microinjection of calcium buffers appears to be due to diffusion of the buffer across the egg cytoplasm rather than to the induction of the activation wave. We conclude that InsP3 diffuses through the egg cytoplasm much more readily than calcium ions and that calcium-stimulated production of InsP3 and InsP3-induced calcium release from an internal store can account for the progressive release of calcium at fertilization.

scholarly journals Nicotinic acid-adenine dinucleotide phosphate mobilizes Ca2+ from a thapsigargin-insensitive pool

1996 ◽  
Vol 315 (3) ◽  
pp. 721-725 ◽  
Author(s):  
Armando A. GENAZZANI ◽  
Antony GALIONE
Keyword(s):  
Nicotinic Acid ◽  
Sea Urchin ◽  
Cross Talk ◽  
Inositol Trisphosphate ◽  
Sea Urchin Eggs ◽  
Bivalent Cations ◽  
Sea Urchin Egg ◽  
Different Characteristics ◽  
Degree Of Overlap

Nicotinic acid–adenine dinucleotide phosphate (NAADP) is a novel intracellular Ca2+ releasing agent recently described in sea-urchin eggs and egg homogenates. Ca2+ release by NAADP is independent of that induced by either inositol trisphosphate (InsP3) or cyclic adenosine dinucleotide phosphate (cADPR). We now report that in sea urchin egg homogenates, NAADP releases Ca2+ from a Ca2+ pool that is distinct from those that are sensitive to InsP3 and cADPR. This organelle has distinct Ca2+ uptake characteristics: it is insensitive to thapsigargin and cyclopiazoic acid, but maintenance of the pool shows some requirement for ATP. Although the different Ca2+ pools have different characteristics, there appears to be some degree of overlap or cross-talk between the NAADP- and cADPR/InsP3-sensitive Ca2+ pools. Ca2+-induced Ca2+ release is unlikely to account for the apparent overlap between stores, since NAADP-induced Ca2+ release, in contrast with that stimulated by cADPR, is not potentiated by bivalent cations.

Psammechinus miliaris egg homogenate as a model to investigate Ca2+-release mechanisms

1999 ◽  
Vol 79 (2) ◽  
pp. 323-326 ◽  
Author(s):  
Armando A. Genazzani ◽  
Heather L. Wilson ◽  
Antony Galione
Keyword(s):  
Sea Urchin ◽  
Calcium Release ◽  
Lytechinus Pictus ◽  
Release Mechanisms ◽  
Psammechinus Miliaris ◽  
Sea Urchin Egg ◽  
Cyclic Adp Ribose ◽  
The Usa ◽  
Release Model ◽  
Convenient Model

The sea urchin egg has proved a reliable and robust system for measuring intracellular calcium release in response to three independent mechanisms: inositol 1,4,5 trisphosphate, cyclic ADP-ribose and the recently identified molecule, nicotinic acid adenine dinucleotide phosphate (NAADP). These calcium release mechanisms have been studied in homogenates of Lytechinus pictus and Spongylocentrotus purpuratus, which are two sea urchin species located off the west coast of the USA. A new calcium-release model from a species of sea urchin present off the coasts of Britain, Psammechinus miliaris is characterized and described. Although the Ca2+-release characteristics in this species do not differ from those of the other two sea urchin species, it may provide a more economical and convenient model for European scientists.

scholarly journals Cortical localization of a calcium release channel in sea urchin eggs.

1992 ◽  
Vol 116 (5) ◽  
pp. 1111-1121 ◽  
Author(s):  
S M McPherson ◽  
P S McPherson ◽  
L Mathews ◽  
K P Campbell ◽  
F J Longo
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Ryanodine Receptor ◽  
Sea Urchin ◽  
Calcium Release ◽  
Staining Pattern ◽  
Cortical Granule ◽  
Calcium Release Channel ◽  
Release Channel ◽  
Sea Urchin Eggs ◽  
Sea Urchin Egg

We have used an antibody against the ryanodine receptor/calcium release channel of skeletal muscle sarcoplasmic reticulum to localize a calcium release channel in sea urchin eggs. The calcium release channel is present in less than 20% of immature oocytes, where it does not demonstrate a specific cytoplasmic localization, while it is confined to the cortex of all mature eggs examined. This is in contrast to the cortical and subcortical localization of calsequestrin in mature and immature eggs. Immunolocalization of the calcium release channel reveals a cortical reticulum or honeycomb staining network that surrounds cortical granules and is associated with the plasma membrane. The network consists of some immunoreactive electron-dense material coating small vesicles and elongate cisternae of the endoplasmic reticulum. The fluorescent reticular staining pattern is lost when egg cortices are treated with agents known to affect sarcoplasmic reticulum calcium release and induce cortical granule exocytosis (ryanodine, calcium, A-23187, and caffeine). An approximately 380-kD protein of sea urchin egg cortices is identified by immunoblot analysis with the ryanodine receptor antibody. These results demonstrate: (a) the presence of a ryanodine-sensitive calcium release channel that is located within the sea urchin egg cortex; (b) an altered calcium release channel staining pattern as a result of treatments that initiate the cortical granule reaction; and (c) a spatial and functional dichotomy of the ER which may be important in serving different roles in the mobilization of calcium at fertilization.

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