scholarly journals Mechanism for Increase in Intracellular Concentration of Free Calcium in Fertilized Sea Urchin Egg

1974 ◽  
Vol 63 (3) ◽  
pp. 374-388 ◽  
Author(s):  
Masahisa Nakamura ◽  
Ikuo Yasumasu
Keyword(s):  
Dissociation Constant ◽  
Sea Urchin ◽  
Calcium Ion ◽  
Calcium Binding ◽  
Intracellular Concentration ◽  
Sodium Ion ◽  
Free Calcium ◽  
Binding Ability ◽  
Sea Urchin Egg ◽  
Fertilized Egg

Intracellular free calcium concentration in the sea urchin egg was calculated to increase from 0.1 mM in an unfertilized egg to 1 mM in a fertilized egg 10 min after fertilization, based on measurement of the dissociation constant between free calcium and sea urchin egg homogenate. The dissociation constant between free calcium (dialyzable calcium) and homogenate of sea urchin eggs was measured by means of dialysis equilibrium. The dissociation constant of the unfertilized egg was about 10–4 M and that of the fertilized egg was about 10–3 M in three species of sea urchin, Hemicentrotus pulcherrimus, Anthocidaris crassispina, and Pseudocentrotus depressus. An increase in the dissociation constant of the unfertilized egg homogenate was observed after the addition of calcium ion at a concentration above 0.3 mM, the dissociation constant becoming the same as that observed in the fertilized egg homogenate after the administration of CaCl2 at a concentration above 1 mM. Sodium ion also caused a decrease in the calcium-binding ability of the unfertilized egg homogenate. Therefore, penetration of calcium ion or sodium ion upon fertilization might induce an increase in the dissociation constant and then intracellular concentration of free calcium would increase at fertilization. Almost all calcium-binding ability of the egg homogenate was found in the microsomal fraction, and the substance which bound calcium was thought to be protein in nature, since trypsin could decrease the level of calcium-binding substance in the homogenate of the eggs.

A study of the Ca2+ – Arsenazo III system and its application to the spectrophotometric determination of free calcium in solution

1990 ◽  
Vol 68 (11) ◽  
pp. 1932-1936 ◽  
Author(s):  
Byron Kratochvil ◽  
Xi-Wen He
Keyword(s):  
Ionic Strength ◽  
Calcium Ion ◽  
Calcium Binding ◽  
Metal Ion ◽  
Arsenazo Iii ◽  
Free Calcium ◽  
Ionic Calcium ◽  
Free Metal ◽  
Free Metal Ion

A two-wavelength method was applied to the determination of free, ionic calcium with Arsenazo III in solutions containing calcium-binding ligands. By this procedure impurities in the indicator can be corrected for, thereby allowing the use of commercial indicator preparations with purities as low as 80%. Only a 1:1 complex with a conditional log stability constant of 4.28 ± 0.13 at pH 4.6 and ionic strength 0.1 was found under the conditions studied. Key words: free metal ion determination, calcium ion speciation, spectrophotometry, arsenazo III, ion increment method for speciation.

Wave of free calcium at fertilization in the sea urchin egg visualized with fura-2

1988 ◽  
Vol 9 (3) ◽  
pp. 271-277 ◽  
Author(s):  
Mathias Hafner ◽  
Christian Petzelt ◽  
Rainer Nobiling ◽  
James B. Pawley ◽  
Douglas Kramp ◽  
...  
Keyword(s):  
Sea Urchin ◽  
Free Calcium ◽  
Fura 2 ◽  
Sea Urchin Egg

scholarly journals Calcium-binding modulator protein from the unfertilized egg of the sea urchin Arbacia punctulata.

1979 ◽  
Vol 80 (1) ◽  
pp. 211-218 ◽  
Author(s):  
J F Head ◽  
S Mader ◽  
B Kaminer
Keyword(s):  
Sea Urchin ◽  
Calcium Binding ◽  
Troponin I ◽  
Binding Protein ◽  
Bovine Brain ◽  
Calcium Binding Protein ◽  
Free Calcium ◽  
Affinity Column ◽  
Arbacia Punctulata ◽  
Peptide Map

We have purified and partly characterized a calcium-binding protein from the unfertilized egg of the sea urchin Arbacia punctulata. This protein closely resembles the calcium-binding modulator protein of bovine brain in its molecular weight, electrophoretic mobility, amino acid analysis, and peptide map. It activates bovine brain phosphodiesterase in the presence of calcium but has no effect on the phosphodiesterase of the Arbacia egg. Densitometric scanning of acrylamide gels of arbacia egg homogenates shows the modulator protein to represent 0.1% of the total protein of the egg. At 10(-4) M free calcium, the protein binds four calcium ions per 17,000-dalton molecule. We have used a column of rabbit skeletal muscle troponin-I covalently coupled to Sepharose 4B as an affinity column to selectively purify the Arbacia egg calcium-binding protein. This column has also been used to purify bovine brain modulator protein and may prove of general use in isolating similar proteins from other sources. The technique may be particularly helpful when only small quantities of starting material are available.

scholarly journals The amino acid sequence, immunofluorescence and microinjection studies on the 15kDa calcium-binding protein from sea urchin egg.

1988 ◽  
Vol 13 (6) ◽  
pp. 525-532 ◽  
Author(s):  
Hiroshi Hosoya ◽  
Takashi Takagi ◽  
Issei Mabuchi ◽  
Hisashi Iwaasa ◽  
Hikoichi Saka ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Sea Urchin ◽  
Calcium Binding ◽  
Binding Protein ◽  
Calcium Binding Protein ◽  
Sea Urchin Egg

Exocytosis reconstituted from the sea urchin egg is unaffected by calcium pretreatment of granules and plasma membrane

1988 ◽  
Vol 8 (4) ◽  
pp. 335-343 ◽  
Author(s):  
Tim Whalley ◽  
Michael Whitaker
Keyword(s):  
Plasma Membrane ◽  
Sea Urchin ◽  
Calcium Ions ◽  
Calcium Ion ◽  
Secretory Granules ◽  
Cortical Granules ◽  
Allosteric Activation ◽  
Ion Concentrations ◽  
Sea Urchin Egg ◽  
Reconstituted System

Micromolar calcium ion concentrations stimulate exocytosis in a reconstituted system made by recombining in the plasma membrane and cortical secretory granules of the sea urchin egg. The isolated cortical granules are unaffected by calcium concentrations up to 1 mM, nor do granule aggregates undergo any mutual fusion at this concentration. Both isolated plasma membrane and cortical granules can be pretreated with 1 mM Ca before reconstitution without affecting the subsequent exocytosis of the reconstituted system in response to micromolar calcium concentrations. On reconstitution, aggregated cortical granules will fuse with one another in response to micromolar calcium provided that one of their number is in contact with the plasma membrane. If exocytosis involves the generation of lipid fusogens, then these results suggest that the calcium-stimulated production of a fusogen can occur only when contiguity exists between cortical granules and plasma membrane. They also suggest that a substance involved in exocytosis can diffuse and cause piggy-back fusion of secretory granules that are in contact with the plasma membrane. Our results are also consistent with a scheme in which calcium ions cause a reversible, allosteric activation of an exocytotic protein.

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

2000 ◽  
Vol 346 (3) ◽  
pp. 743-749 ◽  
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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