Probing Ca2+ release mechanisms using sea urchin egg homogenates

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.

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Nicotinate-adenine dinucleotide phosphate-induced Ca2+-release does not behave as a Ca2+-induced Ca2+-release system

Biochemical Journal ◽

10.1042/bj3160709 ◽

1996 ◽

Vol 316 (3) ◽

pp. 709-711 ◽

Cited By ~ 77

Author(s):

Eduardo N. CHINI ◽

Thomas P. DOUSA

Keyword(s):

Sea Urchin ◽

The Other ◽

Release Mechanism ◽

Inositol 1 ◽

Release System ◽

Release Mechanisms ◽

Sea Urchin Egg ◽

Wide Range ◽

Cyclic Adp Ribose ◽

Regulatory Impact

We investigated the dependence of nicotinate–adenine dinucleotide phosphate (NAADP)-induced Ca2+ release from intracellular stores of sea urchin egg homogenates, upon extravesicular Ca2+. In contrast to the Ca2+ release induced by inositol 1´,4´,5´trisphosphate (IP3) or cyclic ADP-ribose (cADPR), the Ca2+ release induced by NAADP was completely independent of the free extravesicular Ca2+ over a wide range of concentrations (0–0.1 mM). The Ca2+ release triggered by either cADPR or IP3 was biphasically modulated by extravesicular Ca2+, and the Ca2+ release by these agents was abolished when the extravesicular Ca2+ was removed by chelation with 2 mM EGTA. On the other hand, NAADP-triggered Ca2+ release was not influenced by EGTA. These data indicate that while both cADPR and IP3 systems behave as functional Ca2+-induced Ca2+ release mechanisms, NAADP activates a Ca2+ release mechanism which is independent of the presence of extravesicular Ca2+. Therefore, the NAADP-sensitive Ca2+ release mechanisms may have a unique regulatory impact upon intracellular Ca2+ homoeostasis.

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Assembly of unfertilized sea urchin egg tubulin at physiological temperatures.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)32654-1 ◽

1983 ◽

Vol 258 (7) ◽

pp. 4518-4525 ◽

Cited By ~ 2

Author(s):

K A Suprenant ◽

L I Rebhun

Keyword(s):

Sea Urchin ◽

Sea Urchin Egg

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A Ribonucleoprotein Which Catalyzes Thiol-Disulfide Exchange in the Sea Urchin Egg

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)96114-4 ◽

1967 ◽

Vol 242 (7) ◽

pp. 1458-1461

Author(s):

Hikoichi Sakai

Keyword(s):

Sea Urchin ◽

Disulfide Exchange ◽

Sea Urchin Egg

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Different Ca2+-releasing abilities of sperm extracts compared with tissue extracts and phospholipase C isoforms in sea urchin egg homogenate and mouse eggs

Biochemical Journal ◽

10.1042/bj3460743 ◽

2000 ◽

Vol 346 (3) ◽

pp. 743-749 ◽

Cited By ~ 32

Author(s):

Keith T. JONES ◽

Miho MATSUDA ◽

John PARRINGTON ◽

Matilda KATAN ◽

Karl SWANN

Keyword(s):

Phospholipase C ◽

Sea Urchin ◽

Tissue Extracts ◽

Sea Urchin Egg ◽

Boar Sperm ◽

Specific Activities ◽

Mammalian Eggs ◽

Mouse Eggs

A soluble phospholipase C (PLC) from boar sperm generates InsP3 and hence causes Ca2+ release when added to sea urchin egg homogenate. This PLC activity is associated with the ability of sperm extracts to cause Ca2+ oscillations in mammalian eggs following fractionation. A sperm PLC may, therefore, be responsible for causing the observed Ca2+ oscillations at fertilization. In the present study we have further characterized this boar sperm PLC activity using sea urchin egg homogenate. Consistent with a sperm PLC acting on egg PtdIns(4,5)P2, the ability of sperm extracts to release Ca2+ was blocked by preincubation with the PLC inhibitor U73122 or by the addition of neomycin to the homogenate. The Ca2+-releasing activity was also detectable in sperm from other species and in whole testis extracts. However, activity was not observed in extracts from other tissues. Moreover recombinant PLCβ1, -γ1, -γ2, -∆1, all of which had higher specific activities than boar sperm extracts, were not able to release Ca2+ in the sea urchin egg homogenate. In addition these PLCs were not able to cause Ca2+ oscillations following microinjection into mouse eggs. These results imply that the sperm PLC possesses distinct properties that allow it to hydrolyse PtdIns(4,5)P2 in eggs.

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