Calcium-dependent exocytosis in an in vitro secretory granule plasma membrane preparation from sea urchin eggs and the effects of some inhibitors of cytoskeletal function

1983 ◽  
Vol 218 (1213) ◽  
pp. 397-413 ◽  
Keyword(s):  
Plasma Membrane ◽  
Secretory Granule ◽  
Regulatory Protein ◽  
Calcium Sensitivity ◽  
Magnesium Concentration ◽  
Cortical Granule ◽  
Cortical Granules ◽  
Calcium Dependent ◽  
Cortical Granule Exocytosis

Egg cortical granules remain attached to the egg plasma membrane when the egg is ruptured. We present evidence that demonstrates that, when the cytoplasmic face of the egg plasma membrane is exposed to micromolar calcium concentrations, an exocytosis of the cortical granules occurs which corresponds to the cortical granule exocytosis seen when the egg is fertilized. The calcium sensitivity of the preparation is decreased by an increase in magnesium concentration and increased by a decrease in magnesium concentration. Exocytosis is inhibited by trifluoperazine (half inhibition at 6 μm), a drug that inhibits the action of the calciumdependent regulatory protein calmodulin. Colchicine, vinblastine, nocodazole, cytochalasin B, phalloidin N -ethylmaleimide-modified myosin subfragment 1, and antibody to actin are without effect on this in vitro exocytosis at concentrations that far exceed those required to disrupt microtubules and microfilaments. Conditions are such that penetration to the exocytotic site is optimal. It is unlikely, therefore, that either actin or tubulin participate intimately in exocytosis. Our data also exclude on quantitative grounds several other mechanisms postulated to account for the fusion of the secretory granule with the plasma membrane.

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.

Cortical Granule Exocytosis and Fertilization Coat Elevation is Reduced in Aging Sea Urchin Eggs

2000 ◽  
Vol 6 (S2) ◽  
pp. 966-967
Author(s):  
Amitabha Chakrabarti ◽  
Heide Schatten
Keyword(s):  
Plasma Membrane ◽  
Sea Urchin ◽  
Sea Water ◽  
Secretory Granules ◽  
Cortical Granule ◽  
Cortical Granules ◽  
Lytechinus Pictus ◽  
Sea Urchin Eggs ◽  
Cortical Granule Exocytosis ◽  
Granule Secretion

Cortical granules are specialized Golgi-derived membrane-bound secretory granules that are located beneath the plasma membrane in unfertilized sea urchin eggs. Upon fertilization cortical granules discharge in a reaction induced by calcium and release their contents between the plasma membrane and a thin vitelline layer that lines the plasma membrane. Microvilli at the plasma membrane elongate incorporting cortical granule membranes during elongation. The vitelline layer elevates and becomes the egg's fertilization coat that hardens and serves as physical block to polyspermy. While we do not understand the precise mechanisms that participate in cortical granule discharge it is believed that actin plays a role in this process. Because actin and calcium metabolism is affected in aging cells we investigated if cortical granule secretion is affected in aging sea urchin eggs.Lytechinus pictus eggs were obtained by intracoelomic injection of 0.5M KCI to release the eggs into sea water at 23°C.

359 MORPHOLOGIC AND BIOCHEMISTRY ALTERATIONS ON BOVINE OOCYTE MATURATION IN VITRO WITH NITRIC OXIDE AND ITS IMPACT ON EMBRYO DEVELOPMENT

2010 ◽  
Vol 22 (1) ◽  
pp. 336 ◽  
Author(s):  
K. S. Viana ◽  
M. C. C. Bussiere ◽  
C. S. Paes de Carvalho ◽  
B. L. Dias ◽  
M. R. Faes ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Plasma Membrane ◽  
Embryo Development ◽  
Oocyte Maturation ◽  
Control Group ◽  
Cortical Granule ◽  
Bovine Oocyte ◽  
Cortical Granules ◽  
Maturation In Vitro

The aim of this study was to evaluate morphologic and biochemistry alterations caused by the addition of sodium nitroprusside (SNP), a NO donor, on bovine oocyte maturation in vitro. Bovine ovaries were collected at a local abattoir. COC were cultured in TCM-199 with 10% FCS, 0.5 μg mL-1 FSH, 5.0 μg mL-1 LH, and antibiotics. Analysis of variance was conducted and the means were compared by t-test at a level of 5%. Experimental design: (1) evaluation of the oocyte plasma membrane viability and integrity using Annexin V/propidium iodide (PI) and Hoechst 33342/PI staining, respectively; (2) microtubule and microfilament organization, and migration of cortical granules by immunofluorescence; (3) oocyte glutathione content and concentration of NO3-/NO2-using the method of Griess (Ricart-Jane D et al. 2002 Nitric Oxide 6, 178-185) and (4) embryo development. In Experiment 1, the addition of 1 mM SNP caused cellular death in the majority of the oocytes [100%, AnnexinV/PI (+) and 80.7% Hoescht/IP (+)] differing from the control group and the 0.01 mM SNP (P < 0.05). In Experiment 2, the microtubule staining was observed in the cytoplasm in both control group and 0.01 mM SNP; however, the group treated with 1 mM of SNP exhibited clear defects in spindle and chromatin arrangements (P < 0.05). No alterations in microfilaments disposition was observed in the control group and 0.01 mM SNP. However, after the addition of 1 mM, the microfilaments arranged into clusters, and not below of the cortex. Oocytes treated with 1 mM SNP (68.2%) showed total cortical granule migration to the periphery of the ooplasm and were similar to the control group (72.2%) (P > 0.05). Nevertheless, in the group treated with 0.01 mM SNP the total cortical granule migration was greater (86.8%, P < 0.05). In Experiment 3, the glutathione content of oocytes cultured in the presence of 1 mM SNP was lower (4.4p mol) when compared to the control group (5.4p mol) and 0.01 mM SNP (5.5 pmol) (P > 0.05). The concentration of NO in the medium were similar to both control group (6.0 ± 3.0 μM) and treated with 0.01 mM SNP (15.8 ± 1.9 μM), however, the treatment with 1 mM SNP increased 10 times (59.9 ± 12.0 μM; P < 0.05) this concentration. In Experiment 4, cleavage rates and embryo development were similar for groups control and 0.01 mM SNP (P > 0.05). Even so, in the group treated with 0.01 mM there was a greater blastocyst cell number when compared to the control group (256.8 ± 52.5 and 196.9 ± 54.0, respectively-P < 0.05). These results indicate that: (1) the addition of 0.01 mM SNP increased the quality of the oocyte maturation, leading to a higher percentage of cortical granules migration and blastocyst cell numbers, in a different pathway from that of glutathione; (2) the addition of 1 mM of SNP caused a cytotoxic effect, leading to cellular death with loss of viability and integrity of plasma membrane, absence of nuclear maturation/organization of cytoskeleton and reduction of the glutathione content, although with no intervention in the migration of cortical granules.

scholarly journals Isolation and characterization of plasma membrane-associated cortical granules from sea urchin eggs

1977 ◽  
Vol 75 (3) ◽  
pp. 899-914 ◽  
Author(s):  
NK Detering ◽  
GL Decker ◽  
ED Schmell ◽  
WJ Lennarz
Keyword(s):  
Plasma Membrane ◽  
Specific Radioactivity ◽  
Surface Glycoprotein ◽  
Soluble Form ◽  
Cortical Granule ◽  
Initial Surface ◽  
Cortical Granules ◽  
Isolation And Characterization

Cortical granules, which are specialized secretory organelles found in ova of many organisms, have been isolated from the eggs of the sea urchins Arbacia punctulata and Strongylocentrtus pupuratus by a simple, rapid procedure. Electron micropscope examination of cortical granules prepared by this procedure reveals that they are tightly attached to large segments of the plasma membrane and its associated vitelline layer. Further evidence that he cortical granules were associated with these cell surface layers was obtained by (125)I-labeling techniques. The cortical granule preparations were found to be rich in proteoesterase, which was purified 32-fold over that detected in a crude homogenate. Similarly, the specific radioactivity of a (125)I-labeled, surface glycoprotein was increased 40-fold. These facts, coupled with electron microscope observations, indicate the isolation procedure yields a preparation in which both the cortical granules and the plasma membrane-vitelline layer are purified to the same extent. Gel electrophoresis of the membrane-associated cortical granule preparation reveals the presence of at least eight polypeptides. The major polypeptide, which is a glycotprotein of apparent mol wt of 100,000, contains most of the radioactivity introduced by (125)I-labeling of the intact eggs. Lysis of the cortical granules is observed under hypotonic conditions, or under isotonic conditions if Ca(2+) ion is present. When lysis is under isotonic conditions is induced by addition of Ca(2+) ion, the electron-dense contents of the granules remain insoluble. In contrast, hypotonic lysis results in release of the contents of the granule in a soluble form. However, in both cases the (125)I-labeled glycoprotein remains insoluble, presumably because it is a component of either the plasma membrane or the vitelline layer. All these findings indicate that, using this purified preparation, it should be possible to carry out in vitro studies to better define some of the initial, surface-related events observed in vivo upon fertilization.

scholarly journals Evidence for involvement of metalloendoproteases in a step in sea urchin gamete fusion.

1988 ◽  
Vol 107 (2) ◽  
pp. 539-544 ◽  
Author(s):  
J L Roe ◽  
H A Farach ◽  
W J Strittmatter ◽  
W J Lennarz
Keyword(s):  
Plasma Membrane ◽  
Membrane Fusion ◽  
Sea Urchin ◽  
Acrosome Reaction ◽  
Fusion Process ◽  
Cortical Granule ◽  
Cortical Granules ◽  
Gamete Fusion ◽  
Cortical Granule Exocytosis ◽  
Cytoplasmic Continuity

Membrane fusion events are required in three steps in sea urchin fertilization: the acrosome reaction in sperm, fusion of the plasma membrane of acrosome-reacted sperm with the plasma membrane of the egg, and exocytosis of the contents of the egg cortical granules. We recently reported the involvement of a Zn2+-dependent metalloendoprotease in the acrosome reaction (Farach, H. C., D. I. Mundy, W. J. Strittmatter, and W. J. Lennarz. 1987. J. Biol. Chem. 262:5483-5487). In the current study, we investigated the possible involvement of metalloendoproteases in the two other fusion events of fertilization. The use of inhibitors of metalloendoproteases provided evidence that at least one of the fusion events subsequent to the acrosome reaction requires such enzymes. These inhibitors did not block the binding of sperm to egg or the process of cortical granule exocytosis. However, sperm-egg fusion, assayed by the ability of the bound sperm to establish cytoplasmic continuity with the egg, was inhibited by metalloendoprotease substrate. Thus, in addition to the acrosome reaction, an event in the gamete fusion process requires a metalloendoprotease.

Cortical granule exocytosis is triggered by different thresholds of calcium during fertilisation in sea urchin eggs

Zygote ◽  
1998 ◽  
Vol 6 (1) ◽  
pp. 55-63 ◽  
Author(s):  
John C. Matese ◽  
David R. McClay
Keyword(s):  
Plasma Membrane ◽  
Sea Urchin ◽  
Calcium Release ◽  
Threshold Concentration ◽  
Calcium Wave ◽  
Cortical Granule ◽  
Cortical Granules ◽  
Granule Exocytosis ◽  
Sea Urchin Eggs ◽  
Cortical Granule Exocytosis

SummaryIn sea urchin eggs, fertilisation is followed by a calcium wave, cortical granule exocytosis and fertilisation envelope elevation. Both the calcium wave and cortical granule exocytosis sweep across the egg in a wave initiated at the point of sperm entry. Using differential interference contrast (DIC) microscopy combined with laser scanning confocal microscopy, populations of cortical granules undergoing calcium-induced exocytosis were observed in living urchin eggs. Calcium imaging using the indicator Calcium Green-dextran was combined with an image subtraction technique for visual isolation of individual exocytotic events. Relative fluorescence levels of the calcium indicator during the fertilisation wave were compared with cortical fusion events. In localised regions of the egg, there is a 6s delay between the detection of calcium release and fusion of cortical granules. The rate of calcium accumulation was altered experimentally to ask whether this delay was necessary to achieve a threshold concentration of calcium to trigger fusion, or was a time-dependent activation of the cortical granule fusion apparatus after the ‘triggering’ event. Calcium release rate was attenuated by blocking inositol 1,4,5-triphospate (InsP3)-gated channels with heparin. Heparin extended the time necessary to achieve a minimum concentration of calcium at the sites of cortical granule exocytosis. The data are consistent with the conclusion that much of the delay observed normally is necessary to reach threshold concentration of calcium. Cortical granules then fuse with the plasma membrane. Further, once the minimum threshold calcium concentration is reached, cortical granule fusion with the plasma membrane occurs in a pattern suggesting that cortical granules are non-uniform in their calcium sensitivity threshold.

scholarly journals Pleiotropic effects of alpha-SNAP M105I mutation on oocyte biology: ultrastructural and cellular changes that adversely affect female fertility in mice

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Matilde de Paola ◽  
María Paz Miró ◽  
Marcelo Ratto ◽  
Luis Federico Bátiz ◽  
Marcela Alejandra Michaut
Keyword(s):  
Ultrastructural Level ◽  
Fertilization Rate ◽  
Fertilization Success ◽  
Female Fertility ◽  
Cortical Granule ◽  
Cortical Granules ◽  
Negative Effects ◽  
Cortical Granule Exocytosis ◽  
Oval Shape

AbstractAfter sperm-oocyte fusion, cortical granules (CGs) located in oocyte cortex undergo exocytosis and their content is released into the perivitelline space to avoid polyspermy. Thus, cortical granule exocytosis (CGE) is a key process for fertilization success. We have demonstrated that alpha-SNAP -and its functional partner NSF- mediate fusion of CGs with the plasma membrane in mouse oocytes. Here, we examined at cellular and ultrastructural level oocytes from hyh (hydrocephalus with hop gait) mice, which present a missense mutation in the Napa gene that results in the substitution of methionine for isoleucine at position 105 (M105I) of alpha-SNAP. Mutated alpha-SNAP was mislocalized in hyh oocytes while NSF expression increased during oocyte maturation. Staining of CGs showed that 9.8% of hyh oocytes had abnormal localization of CGs and oval shape. Functional tests showed that CGE was impaired in hyh oocytes. Interestingly, in vitro fertilization assays showed a decreased fertilization rate for hyh oocytes. Furthermore, fertilized hyh oocytes presented an increased polyspermy rate compared to wild type ones. At ultrastructural level, hyh oocytes showed small mitochondria and a striking accumulation and secretion of degradative structures. Our findings demonstrate the negative effects of alpha-SNAP M105 mutation on oocyte biology and further confirm the relevance of alpha-SNAP in female fertility.

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.

scholarly journals Selective Ca2+-dependent interaction of calmodulin with the head domain of synapsin 1

1991 ◽  
Vol 275 (1) ◽  
pp. 93-97 ◽  
Author(s):  
N V Hayes ◽  
A F Bennett ◽  
A J Baines
Keyword(s):  
Regulatory Protein ◽  
Critical Element ◽  
Nerve Terminals ◽  
Calcium Dependent ◽  
Calmodulin Binding ◽  
Head Domain ◽  
N Terminus ◽  
Dependent Interaction ◽  
Synapsin 1

The calcium-dependent regulatory protein calmodulin is a critical element in the machinery regulating exocytosis at nerve terminals. Okabe & Sobue [(1987) FEBS Lett. 213, 184-188] showed that calmodulin interacts with one of the proteins intimately connected with the neuronal exocytotic process, i.e. synapsin 1. We have investigated the site at which calmodulin interacts with synapsin 1. We find that it is possible to generate chemically cross-linked Ca2(+)-dependent complexes between synapsin 1 and calmodulin in vitro, and have used covalent cross-linking in conjunction with calmodulin affinity chromatography to identify fragments of synapsin 1 that interact with calmodulin. Ca2(+)-dependent calmodulin binding is restricted to the ‘head’ domain (residues 1-453 in bovine synapsin 1). Within this domain the binding site is located in a unique 11 kDa Staphylococcus aureus V8 proteinase generated fragment. This fragment does not contain the site for cyclic-AMP-dependent phosphorylation and therefore does not represent the N-terminus of the protein.

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