Le rôle du calcium et du potassium dans l'entrée en maturation de l'ceuf de pholade (Barnea Candida)

Fertilization and Artificial Activation in the Egg of the Surf-Clam, Spisula Solidissima

“…It has been shown (Fig. 2) that a lack of an excess of potassium in the Loeb, 1915;Dalcq, 1928b ;Pasteels, 1935). Of the parthenogenetic agents tried by Wison and Heilbrunn (1952), calcium was the only one which caused the cortex to stiffen.…”

Modulators of calcium signalling at fertilization

“…Despite this early scientific interest in fertilization, it was not until almost 60 years later that Lionel Jaffe and co-workers discovered that the sperm initiates a wave of calcium (Ca 2+ ) across the egg (as initially proposed by Dalcq in 1928 [ 2 ]) and that this signal triggers the formation of a ‘rejuvenated individual’—the newly developing embryo [ 3 , 4 ]. These first experiments documenting that Ca 2+ initiates embryonic development at fertilization were performed in eggs of medaka, a freshwater fish, and were made possible by the identification of jellyfish aequorin as a bioluminescent Ca 2+ -sensing protein [ 5 ].…”

“…The elements that unite are single cells, each usually incapable, under natural conditions, of continued existence or development-on the point of death; but by their union a rejuvenated individual is formed which constitutes a link in the eternal procession of life by virtue of its power of reproduction. [1] Despite this early scientific interest in fertilization, it was not until almost 60 years later that Lionel Jaffe and co-workers discovered that the sperm initiates a wave of calcium (Ca 2+ ) across the egg (as initially proposed by Dalcq in 1928 [2]) and that this signal triggers the formation of a 'rejuvenated individual'-the newly developing embryo [3,4]. These first experiments documenting that Ca 2+ initiates embryonic development at fertilization were performed in eggs of medaka, a freshwater fish, and were made possible by the identification of jellyfish aequorin as a bioluminescent Ca 2+ -sensing protein [5].…”

Intracellular pH change does not appear as a prerequisite for triggering activation of Barnea candida (Mollusca, Pelecypoda) oocytes

“…Fertilization or KC1-induced activation involve both an uptake of calcium and a release of protons [Dalcq, 1928;Pasteels, 1938;Allen, 1953;Schuetz, 1975;Ii and Rebhun, 1979;Finkel and Wolf, 1980;Dube and Guerrier, 1982a,b;Dube et al, 1982;Guerrier et al, 19811. H + release alone appears insufficient to trigger germinal vesicle breakdown (GVBD) since inhibiting the calcium uptake, but not the acid release, efficiently blocks this process [Guerrier et al, 1981;Dube and Guerrier, 1982al.…”