scholarly journals Rab3A, a possible marker of cortical granules, participates in cortical granule exocytosis in mouse eggs

2016 ◽  
Vol 347 (1) ◽  
pp. 42-51 ◽  
Author(s):  
Oscar Daniel Bello ◽  
Andrea Isabel Cappa ◽  
Matilde de Paola ◽  
María Natalia Zanetti ◽  
Mitsunori Fukuda ◽  
...  
Keyword(s):  
Cortical Granule ◽  
Cortical Granules ◽  
Granule Exocytosis ◽  
Cortical Granule Exocytosis ◽  
Mouse Eggs

scholarly journals Compensatory endocytosis occurs after cortical granule exocytosis in mouse eggs

2019 ◽  
Vol 235 (5) ◽  
pp. 4351-4360
Author(s):  
Matías D. Gómez‐Elías ◽  
Rafael A. Fissore ◽  
Patricia S. Cuasnicú ◽  
Débora J. Cohen
Keyword(s):  
Cortical Granule ◽  
Granule Exocytosis ◽  
Cortical Granule Exocytosis ◽  
Mouse Eggs

scholarly journals Poisson-distributed active fusion complexes underlie the control of the rate and extent of exocytosis by calcium.

1996 ◽  
Vol 134 (2) ◽  
pp. 329-338 ◽  
Author(s):  
S S Vogel ◽  
P S Blank ◽  
J Zimmerberg
Keyword(s):  
Poisson Process ◽  
Sea Urchin ◽  
Physiological Responses ◽  
Cortical Granule ◽  
Cortical Granules ◽  
Granule Exocytosis ◽  
Calcium Dependence ◽  
Sea Urchin Egg ◽  
High Calcium ◽  
Cortical Granule Exocytosis

We have investigated the consequences of having multiple fusion complexes on exocytotic granules, and have identified a new principle for interpreting the calcium dependence of calcium-triggered exocytosis. Strikingly different physiological responses to calcium are expected when active fusion complexes are distributed between granules in a deterministic or probabilistic manner. We have modeled these differences, and compared them with the calcium dependence of sea urchin egg cortical granule exocytosis. From the calcium dependence of cortical granule exocytosis, and from the exposure time and concentration dependence of N-ethylmaleimide inhibition, we determined that cortical granules do have spare active fusion complexes that are randomly distributed as a Poisson process among the population of granules. At high calcium concentrations, docking sites have on average nine active fusion complexes.

Weak bases partially activate Xenopus eggs and permit changes in membrane conductance whilst inhibiting cortical granule exocytosis

1987 ◽  
Vol 87 (2) ◽  
pp. 205-220
Author(s):  
M. Charbonneau ◽  
D.J. Webb
Keyword(s):  
Polar Body ◽  
Membrane Conductance ◽  
Transient Increase ◽  
Cortical Granule ◽  
Cortical Granules ◽  
Weak Base ◽  
Granule Exocytosis ◽  
Weak Bases ◽  
Prolonged Contact ◽  
Cortical Granule Exocytosis

At extracellular pH values close to their pKa values the weak bases, ammonia and procaine, elicited a series of events in non-activated Xenopus eggs, some of which resembled those normally occurring at fertilization. These included: (1) a transient increase in membrane conductance; (2) modification of the microvilli; (3) thickening of the cortical cytoplasm and displacement of the cortical granules; (4) pigment accumulation; (5) contractions and shape changes. However, these eggs did not undergo the cortical reaction nor emit the second polar body. Cortical granule exocytosis of inseminated or artificially stimulated eggs was inhibited if the eggs had been previously treated for 15 min with the weak base and subsequently rinsed. Multiple sperm-entry sites were exhibited by the inseminated eggs, suggesting polyspermy. However, such eggs did not cleave and although sperm had fused with the egg membrane, they were not incorporated. Nevertheless, a transient increase in membrane conductance was evoked, which was longer in duration and had a slightly different form from that normally accompanying fertilization. In these eggs cortical granules were intact but displaced away from the plasma membrane. Prolonged contact with the weak base rendered eggs totally unresponsive to sperm or artificial stimuli but eggs recovered when rinsed sufficiently. These effects of weak bases on unfertilized Xenopus eggs or during fertilization were completely absent at pH 7.4. Although changes in intracellular pH or Ca2+ may be involved in these phenomena, direct action by the weak base itself cannot be ruled out.

The dynamics of plasma membrane PtdIns(4,5)P2 at fertilization of mouse eggs

2002 ◽  
Vol 115 (10) ◽  
pp. 2139-2149 ◽  
Author(s):  
Guillaume Halet ◽  
Richard Tunwell ◽  
Tamas Balla ◽  
Karl Swann ◽  
John Carroll
Keyword(s):  
Plasma Membrane ◽  
De Novo ◽  
Confocal Imaging ◽  
Cortical Granule ◽  
Cortical Granules ◽  
Vegetal Cortex ◽  
Living Mouse ◽  
Cortical Granule Exocytosis ◽  
Phosphatidylinositol 4 ◽  
Mouse Eggs

A series of intracellular Ca2+ oscillations are responsible for triggering egg activation and cortical granule exocytosis at fertilization in mammals. These Ca2+ oscillations are generated by an increase in inositol 1,4,5-trisphosphate [Ins(1,4,5)P3], which results from the hydrolysis of phosphatidylinositol 4,5-bisphosphate[PtdIns(4,5)P2]. Using confocal imaging to simultaneously monitor Ca2+ and plasma membrane PtdIns(4,5)P2in single living mouse eggs we have sought to establish the relationship between the kinetics of PtdIns(4,5)P2 metabolism and the Ca2+ oscillations at fertilization. We report that there is no detectable net loss of plasma membrane PtdIns(4,5)P2either during the latent period or during the subsequent Ca2+oscillations. When phosphatidylinositol 4-kinase is inhibited with micromolar wortmannin a limited decrease in plasma membrane PtdIns(4,5)P2 is detected in half the eggs studied. Although we were unable to detect a widespread loss of PtdIns(4,5)P2, we found that fertilization triggers a net increase in plasma membrane PtdIns(4,5)P2 that is localized to the vegetal cortex. The fertilization-induced increase in PtdIns(4,5)P2 follows the increase in Ca2+, is blocked by Ca2+ buffers and can be mimicked, albeit with slower kinetics, by photoreleasing Ins(1,4,5)P3. Inhibition of Ca2+-dependent exocytosis of cortical granules, without interfering with Ca2+ transients, inhibits the PtdIns(4,5)P2 increase. The increase appears to be due to de novo synthesis since it is inhibited by micromolar wortmannin. Finally,there is no increase in PtdIns(4,5)P2 in immature oocytes that are not competent to extrude cortical granules. These studies suggest that fertilization does not deplete plasma membrane PtdIns(4,5)P2 and that one of the pathways for increasing PtdIns(4,5)P2 at fertilization is invoked by exocytosis of cortical granules.

Dynamics of cortical granule exocytosis at fertilization in living mouse eggs

1996 ◽  
Vol 270 (5) ◽  
pp. C1354-C1361 ◽  
Author(s):  
M. Tahara ◽  
K. Tasaka ◽  
N. Masumoto ◽  
A. Mammoto ◽  
Y. Ikebuchi ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Cortical Granule ◽  
Free Calcium ◽  
Cortical Granules ◽  
Acetoxymethyl Ester ◽  
Living Mouse ◽  
Cortical Granule Exocytosis ◽  
Mouse Eggs

Sperm-egg fusion induces an intracellular free calcium concentration ([Ca2+]i) increase and exocytosis of cortical granules (CGs). Recently we used an impermeable fluorescent membrane probe, 1-[4-(trimethylammonio)phenyl]-6-phenyl-1,3,5-hexatriene (TMA-DPH), to develop a method to evaluate the kinetics of exocytosis in single living cells. In this study we used digital imaging and confocal laser scanning microscopy to evaluate CG exocytosis in living mouse eggs with TMA-DPH. Time-related changes of CG exocytosis were estimated as the percent increase of TMA-DPH fluorescence. The increase of fluorescence in the egg started after sperm attachment, continued at an almost uniform rate, and ceased at 45-60 min. Whereas the [Ca2+]i increase at fertilization was transient or oscillatory, exocytosis was not always induced concomitantly with each [Ca2+]i peak. Next we used this method to determine some intracellular mediators of exocytosis in the egg. An intracellular calcium chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester, and a microfilament inhibitor, cytochalasin B, blocked sperm-induced exocytosis. A guanosine 5'-triphosphate-binding protein activator, AlF4-, induced exocytosis. These results suggest that [Ca2+]i, microfilament, and guanosine 5'-triphosphate-binding proteins may be involved in CG exocytosis. In conclusion, this method has significant advantages for studying exocytosis in living eggs.

SNAP-25 is essential for cortical granule exocytosis in mouse eggs

1998 ◽  
Vol 274 (6) ◽  
pp. C1496-C1500 ◽  
Author(s):  
Yoshihide Ikebuchi ◽  
Nobuyuki Masumoto ◽  
Tetsu Matsuoka ◽  
Takeshi Yokoi ◽  
Masahiro Tahara ◽  
...  
Keyword(s):  
Botulinum Neurotoxin ◽  
Endocrine Cells ◽  
Immunoblot Analysis ◽  
Cortical Granule ◽  
Rt Pcr ◽  
Botulinum Neurotoxin A ◽  
Granule Exocytosis ◽  
Cortical Granule Exocytosis ◽  
And Function ◽  
Mouse Eggs

Synaptosome-associated protein of 25 kDa (SNAP-25) has been shown to play an important role in Ca2+-dependent exocytosis in neurons and endocrine cells. During fertilization, sperm-egg fusion induces cytosolic Ca2+mobilization and subsequently Ca2+-dependent cortical granule (CG) exocytosis in eggs. However, it is not yet clear whether SNAP-25 is involved in this process. In this study, we determined the expression and function of SNAP-25 in mouse eggs. mRNA and SNAP-25 were detected in metaphase II (MII) mouse eggs by RT-PCR and immunoblot analysis, respectively. Next, to determine the function of SNAP-25, we evaluated the change in CG exocytosis with a membrane dye, tetramethylammonium-1,6-diphenyl-1,3,5-hexatriene, after microinjection of a botulinum neurotoxin A (BoNT/A), which selectively cleaves SNAP-25 in MII eggs. Sperm-induced CG exocytosis was significantly inhibited in the BoNT/A-treated eggs. The inhibition was attenuated by coinjection of SNAP-25. These results suggest that SNAP-25 may be involved in Ca2+-dependent CG exocytosis during fertilization in mouse eggs.

Visualization of exocytosis during sea urchin egg fertilization using confocal microscopy

1995 ◽  
Vol 108 (6) ◽  
pp. 2293-2300 ◽  
Author(s):  
M. Terasaki
Keyword(s):  
Confocal Microscopy ◽  
Sea Urchin ◽  
Sea Water ◽  
Fluorescent Labeling ◽  
Cortical Granule ◽  
Cortical Granules ◽  
Granule Exocytosis ◽  
New Methods ◽  
Cortical Granule Exocytosis ◽  
Fluorescent Dextran

A Ca2+ wave at fertilization triggers cortical granule exocytosis in sea urchin eggs. New methods for visualizing exocytosis of individual cortical granules were developed using fluorescent probes and confocal microscopy. Electron microscopy previously provided evidence that cortical granule exocytosis results in the formation of long-lived depressions in the cell surface. Fluorescent dextran or ovalbumin in the sea water seemed to label these depressions and appeared by confocal microscopy as disks. FM 1–43, a water-soluble fluorescent dye which labels membranes in contact with the sea water, seemed to label the membrane of these depressions and appeared as rings. In double-labeling experiments, the disk and ring labeling by the two types of fluorescent dyes were coincident to within 0.5 second. The fluorescent labeling is coincident with the disappearance of cortical granules by transmitted light microscopy, demonstrating that the labeling corresponds to cortical granule exocytosis. Fluorescent labeling was simultaneous with an expansion of the space occupied by the cortical granule, and labeling by the fluorescent dextran was found to take 0.1-0.2 second. These results are consistent with, and reinforce the previous electron microscopic evidence for, long-lived depressions formed by exocytosis; in addition, the new methods provide new ways to investigate cortical granule exocytosis in living eggs. The fluorescence labeling methods were used with the Ca2+ indicator Ca Green-dextran to test if Ca2+ and cortical granule exocytosis are closely related spatially and temporally. In any given region of the cortex, Ca2+ increased relatively slowly.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Activation of protein kinase Cη triggers cortical granule exocytosis in Xenopus oocytes

2002 ◽  
Vol 115 (6) ◽  
pp. 1313-1320
Author(s):  
Cameron B. Gundersen ◽  
Sirus A. Kohan ◽  
Qian Chen ◽  
Joseph Iagnemma ◽  
Joy A. Umbach
Keyword(s):  
Protein Kinase ◽  
Xenopus Oocytes ◽  
Phorbol Esters ◽  
Subcellular Fractionation ◽  
Cortical Granule ◽  
The Novel ◽  
Cortical Granules ◽  
Granule Exocytosis ◽  
The Family ◽  
Cortical Granule Exocytosis

Previous work has shown that phorbol esters or diacylglycerol trigger cortical granule exocytosis in Xenopus oocytes. We sought to identify the isoform(s) of protein kinase C (PKC) that mediate(s) this regulated secretory event. Because this process is initiated by lipid activators of PKC but is independent of calcium ions, we focused on the family of novel(calcium-independent) PKCs. Pharmacological investigations using Gö6976 and Gö6983 tended to exclude PKCδ, ϵ and μ as secretory triggers. Subcellular fractionation and immunoblot data revealed that these oocytes expressed all five members of the novel PKC family, but it was only PKCη that colocalized with cortical granules. Finally, expression of wild type or constitutively active forms of PKCδ and η strongly supported the conclusion that it is PKCη that initiates cortical granule exocytosis in these cells. These observations represent an important step in identifying the mechanism of secretory triggering in this system.

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