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Starfish oocytes that are extracted from the ovaries are arrested at the prophase of the first meiotic division. At this stage of maturation, they are characterized by a large nucleus called the germinal vesicle. Meiosis resumption (maturation) can be induced in vitro by adding the hormone 1-methyladenine (1-MA) to the seawater in which the oocytes are(More)
NAADP participates in the response of starfish oocytes to sperm by triggering the fertilization potential (FP) through the activation of a Ca2+ current which depolarizes the membrane to the threshold of activation of the voltage-gated Ca2+ channels. The aim of this study was to investigate whether this Ca2+ influx is linked to the onset of the concomitant(More)
During the reinitiation of the meiotic cycle (maturation) induced by the hormone 1-methyladenine (1-MA), starfish oocytes undergo structural and biochemical changes in preparation for successful fertilization. Previous work has shown that the sensitivity of internal Ca(2+) stores to InsP(3) increases during maturation of the oocytes. Since Astropecten(More)
The resumption of the meiotic cycle (maturation) induced by 1-methyladenine in prophase-arrested starfish oocytes is indicated by the breakdown of the germinal vesicle and is characterized by the increased sensitivity of the Ca2+ stores to inositol 1,4,5-trisphosphate (InsP3) to InsP3 starting at the animal hemisphere (where the germinal vesicle was(More)
Ca2+ signaling plays a crucial role in virtually all cellular processes, from the origin of new life at fertilization to the end of life when cells die. Both the influx of external Ca2+ through Ca2+-permeable channels and its release from intracellular stores are essential to the signaling function. Intracellular Ca2+ is influenced by mitogenic factors(More)
Cyclic ADP-ribose (cADPr) is a second messenger that regulates intracellular free [Ca2+] ([Ca2+]i) in a variety of cell types, including immature oocytes from the starfish Astropecten auranciacus. In this study, we employed confocal laser scanning microscopy and voltage clamp techniques to investigate the source of the cADPr-elicited Ca2+ wave originating(More)
Cofilin is a small protein that belongs to the family of actin-depolymerizing factors (ADF). The main cellular function of cofilin is to change cytoskeletal dynamics and thus to modulate cell motility and cytokinesis. We have recently demonstrated that the actin cytoskeleton is involved in the modulation of Ca(2+) signalling in starfish oocytes. To extend(More)
Nicotinic acid adenine dinucleotide phosphate (NAADP) is involved in the Ca2+ response observed at fertilization in several species, including starfish. In this study, we have employed Ca2+ imaging and the single-electrode voltage-clamp technique to investigate whether the NAADP-mediated Ca2+ entry discovered in our laboratory in starfish oocytes was(More)
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