The existence of inositol 1,4,5-trisphosphate and ryanodine receptors in mature bovine oocytes

Development ◽  
1995 ◽  
Vol 121 (8) ◽  
pp. 2645-2654 ◽  
Author(s):  
C. Yue ◽  
K.L. White ◽  
W.A. Reed ◽  
T.D. Bunch
Keyword(s):  
Ryanodine Receptors ◽  
Inhibitory Effect ◽  
Ruthenium Red ◽  
Calcium Oscillations ◽  
Ip3 Receptor ◽  
Cyclic Adp Ribose ◽  
Inositol 1,4,5 Trisphosphate ◽  
Bovine Oocytes ◽  
Continuous Injection

Intracellular Ca2+ (Ca2+i) transients during fertilization are critical to the activation of eggs in all species studied. Activation of both the inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) and ryanodine receptor (RYR) are responsible for the calcium oscillations during fertilization in sea urchin eggs. Using in vitro matured bovine oocytes loaded with Fura-2 AM ester as Ca2+i indicator, we addressed whether IP3Rs and RYRs coexist in mammalian eggs. Our results indicate that microinjection of 50–250 nM IP3 or 10–20 mM caffeine, 100–200 microM ryanodine and 4–8 microM cyclic ADP-ribose all induced Ca2+i release. The Ca2+i release induced by 250 nM IP3 could only be inhibited by prior injection of 1 mg/ml heparin which was overcome by continuous injection of IP3 to 1 microM. Prior injection of either 50 microM ruthenium red, 50 microM procaine or 1 % vehicle medium (VM) did not affect the Ca2+i release induced by IP3. Prior injection of heparin or VM did not affect the Ca2+i release induced by 10–20 mM caffeine or 200 microM ryanodine, but prior injection of 50 microM ruthenium red or procaine completely inhibited the effect of 10–20 mM caffeine. In addition, continuous injection of caffeine up to 40 mM overcame the inhibitory effect of ruthenium red or procaine. The same 50 microM concentration of ruthenium red or procaine only partially blocked the effect of 200 microM ryanodine, but 200 microM ruthenium red or procaine completely blocked the effect of 200 microM ryanodine.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals NAADP mobilizes Ca2+ from a thapsigargin-sensitive store in the nuclear envelope by activating ryanodine receptors

2003 ◽  
Vol 163 (2) ◽  
pp. 271-282 ◽  
Author(s):  
Julia V. Gerasimenko ◽  
Yoshio Maruyama ◽  
Kojiro Yano ◽  
Nick J. Dolman ◽  
Alexei V. Tepikin ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Ryanodine Receptors ◽  
Ruthenium Red ◽  
Receptor Blockade ◽  
Ip3 Receptors ◽  
Ip3 Receptor ◽  
Transient Rise ◽  
Cyclic Adp Ribose ◽  
Inositol 1,4,5 Trisphosphate ◽  
Acidic Organelles

Ca2+ release from the envelope of isolated pancreatic acinar nuclei could be activated by nicotinic acid adenine dinucleotide phosphate (NAADP) as well as by inositol 1,4,5-trisphosphate (IP3) and cyclic ADP-ribose (cADPR). Each of these agents reduced the Ca2+ concentration inside the nuclear envelope, and this was associated with a transient rise in the nucleoplasmic Ca2+ concentration. NAADP released Ca2+ from the same thapsigargin-sensitive pool as IP3. The NAADP action was specific because, for example, nicotineamide adenine dinucleotide phosphate was ineffective. The Ca2+ release was unaffected by procedures interfering with acidic organelles (bafilomycin, brefeldin, and nigericin). Ryanodine blocked the Ca2+-releasing effects of NAADP, cADPR, and caffeine, but not IP3. Ruthenium red also blocked the NAADP-elicited Ca2+ release. IP3 receptor blockade did not inhibit the Ca2+ release elicited by NAADP or cADPR. The nuclear envelope contains ryanodine and IP3 receptors that can be activated separately and independently; the ryanodine receptors by either NAADP or cADPR, and the IP3 receptors by IP3.

Regulation of Ca2+-release-activated Ca2+ current (Icrac) by ryanodine receptors in inositol 1,4,5-trisphosphate-receptor-deficient DT40 cells

2001 ◽  
Vol 360 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Kirill KISELYOV ◽  
Dong Min SHIN ◽  
Nikolay SHCHEYNIKOV ◽  
Tomohiro KUROSAKI ◽  
Shmuel MUALLEM
Keyword(s):  
Time Course ◽  
Ryanodine Receptors ◽  
Cell Types ◽  
Ruthenium Red ◽  
General Mechanism ◽  
Inward Rectification ◽  
Wild Type ◽  
Ip3 Receptor ◽  
Inositol 1,4,5 Trisphosphate ◽  
Dt40 Cells

Persistence of capacitative Ca2+ influx in inositol 1,4,5-trisphosphate (IP3) receptor (IP3R)-deficient DT40 cells (DT40IP3R-/−) raises the question of whether gating of Ca2+-release activated Ca2+ current (Icrac) by conformational coupling to Ca2+-release channels is a general mechanism of gating of these channels. In the present work we examined the properties and mechanism of activation of Icrac Ca2+ current in wild-type and DT40IP3R-/− cells. In both cell types passive depletion of internal Ca2+ stores by infusion of EGTA activated a Ca2+ current with similar characteristics and time course. The current was highly Ca2+-selective and showed strong inward rectification, all typical of Icrac. The activator of ryanodine receptor (RyR), cADP-ribose (cADPR), facilitated activation of Icrac, and the inhibitors of the RyRs, 8-N-cADPR, ryanodine and Ruthenium Red, all inhibited Icrac activation in DT40IP3R-/− cells, even after complete depletion of intracellular Ca2+ stores by ionomycin. Wild-type and DT40IP3R-/− cells express RyR isoforms 1 and 3. RyR levels were adapted in DT40IP3R-/− cells to a lower RyR3/RyR1 ratio than in wild-type cells. These results suggest that IP3Rs and RyRs can efficiently gate Icrac in DT40 cells and explain the persistence of Icrac gating by internal stores in the absence of IP3Rs.

201 ROLE OF THE NITRIC OXIDE SYSTEM IN EFFECTS OF PROLACTIN AND GROWTH HORMONE ON METAPHASE-II CHROMOSOMES IN BOVINE OOCYTES AGING IN VITRO

2016 ◽  
Vol 28 (2) ◽  
pp. 231
Author(s):  
I. Lebedeva ◽  
G. Singina ◽  
E. Shedova ◽  
A. Lopukhov ◽  
N. Zinovieva
Keyword(s):  
Nitric Oxide ◽  
Growth Hormone ◽  
Cumulus Cells ◽  
Total Activity ◽  
Inhibitory Effect ◽  
Pituitary Hormones ◽  
Oxide System ◽  
Nos Inhibitors ◽  
Bovine Oocytes

Aging of mammalian oocytes is the time-dependent process of cytological and molecular transformations leading to a decline in the ovum quality and developmental capacity. We have previously shown that 2 related pituitary hormones, prolactin (PRL) and growth hormone (GH), may decelerate abnormal changes in the morphology of metaphase II (MII) chromosomes in bovine cumulus-enclosed oocytes (CEO) aging in vitro. The goal of the present research was to examine the involvement of different isoforms of nitric oxide synthase (NOS) in the actions of PRL and GH on MII chromosomes in aging bovine oocytes. Bovine CEO were matured for 20 h in TCM 199 containing 10% FCS, 10 μg mL–1 porcine FSH, and 10 μg mL–1 ovine LH. After IVM, CEO or denuded oocytes (DO) were cultured for 24 h in the aging medium of TCM 199 supplemented with 10% FCS (control). In experimental groups, the medium contained either 50 ng mL–1 bovine PRL or 10 ng mL–1 bovine GH and/or NOS inhibitors. The following inhibitors were applied: (1) N-propyl-l-arginine (NPLA; an inhibitor of neuronal NOS (nNOS), 5 μM) and (2) L-NAME (an effective inhibitor of both endothelial NOS (eNOS) and nNOS, 20 μM). Destructive changes of MII chromosomes in oocytes were assessed by the following morphological signs: decondensation, partial adherence, chromosome clumping into a single mass, and fragmentation. The total activity of NOS in oocytes was determined by NADPH-diaphorase staining. The data from 4–5 replicates were analysed by ANOVA. During CEO aging in the control medium, the rate of MII oocytes with destructive changes of chromosomes rose from 16.8 ± 2.1% to 58.5 ± 1.4% (P < 0.001), whereas both PRL and GH reduced this rate up to 42.0 ± 1.3% and 46.5 ± 1.6%, respectively (P < 0.001). The nNOS inhibitor NPLA abolished (P < 0.001) the inhibitory effect of PRL on abnormal modifications of chromosomes in CEO but did not affect the frequency of these modifications in the control or GH-treated groups. In the absence of the hormones, L-NAME (the eNOS+nNOS inhibitor) decreased the rate of aging CEOs with chromosome abnormalities from 58.5 ± 1.4% to 41.2 ± 2.5% (P < 0.001), acting unidirectionally with PRL and GH. Meanwhile, L-NAME enhanced (P < 0.05) the suppressing effect of PRL on destructive changes of MII chromosomes but did not influence the similar effect of GH. At the same time the chromosome morphology in senescent DOs was unaffected by the hormones or NOS inhibitors. Furthermore, the total activity of NOS in oocytes separated of cumulus after 24 h of aging was similar in the control and experimental groups. Thus, the inhibitory effect of GH on abnormal modifications of MII chromosomes in aging bovine oocytes may be related to a reduction of the eNOS activity in cumulus cells, whereas the respective effect of PRL is likely to be achieved by both inactivation of eNOS and activation of nNOS. This research was supported by RFBR (No. 13–04–01888).

scholarly journals Defective sperm head decondensation undermines the success of ICSI in the bovine

Reproduction ◽  
2017 ◽  
Vol 154 (3) ◽  
pp. 307-318 ◽  
Author(s):  
Luis Águila ◽  
Ricardo Felmer ◽  
María Elena Arias ◽  
Felipe Navarrete ◽  
David Martin-Hidalgo ◽  
...  
Keyword(s):  
Calcium Oscillations ◽  
Sperm Head ◽  
Oocyte Activation ◽  
Bovine Sperm ◽  
Bovine Oocytes ◽  
Mouse Eggs ◽  
Do So ◽  
Nuclear Decondensation

The efficiency of intracytoplasmic sperm injection (ICSI) in the bovine is low compared to other species. It is unknown whether defective oocyte activation and/or sperm head decondensation limit the success of this technique in this species. To elucidate where the main obstacle lies, we used homologous and heterologous ICSI and parthenogenetic activation procedures. We also evaluated whetherin vitromaturation negatively impacted the early stages of activation after ICSI. Here we showed that injected bovine sperm are resistant to nuclear decondensation by bovine oocytes and this is only partly overcome by exogenous activation. Remarkably, when we used heterologous ICSI,in vivo-matured mouse eggs were capable of mounting calcium oscillations and displaying normal PN formation following injection of bovine sperm, althoughin vitro-matured mouse oocytes were unable to do so. Together, our data demonstrate that bovine sperm are especially resistant to nuclear decondensation byin vitro-matured oocytes and this deficiency cannot be simply overcome by exogenous activation protocols, even by inducing physiological calcium oscillations. Therefore, the inability of a suboptimal ooplasmic environment to induce sperm head decondensation limits the success of ICSI in the bovine. Studies aimed to improve the cytoplasmic milieu ofin vitro-matured oocytes and to replicate the molecular changes associated within vivocapacitation and acrosome reaction will deepen our understanding of the mechanism of fertilization and improve the success of ICSI in this species.

Cyclopiazonic acid induces accelerated progress of meiosis in pig oocytes

Zygote ◽  
1997 ◽  
Vol 5 (3) ◽  
pp. 193-205 ◽  
Author(s):  
Jaroslav Petr ◽  
Jirří Rozinek ◽  
František Jílek
Keyword(s):  
Intracellular Calcium ◽  
Oocyte Maturation ◽  
Ryanodine Receptors ◽  
Cyclopiazonic Acid ◽  
Cumulus Cells ◽  
Ruthenium Red ◽  
Sensitive Period ◽  
Calcium Deposits ◽  
Transient Elevation

SummaryIn mammalian oocytes, calcium plays an important role in the regulation of meiotic maturation. In our study, we used the mycotoxin cyclopiazonic acid (CPA), an inhibitor of calcium-dependent ATPases, to mobilise intracellular calcium deposits during in vitro maturation of pig oocytes. The CPA treatment of maturing oocytes significantly accelerated the progress of their maturation. Oocytes entered the CPA-sensitive period after 21 h of in vitro culture. A very short (5 min) exposure to CPA (100 mM) is sufficient to accelerate maturation and it seems that accelerated maturation can be triggered by a transient elevation of intracellular calcium levels. The effect of CPA is not mediated through the cumulus cells, because maturation is accelerated by CPA treatment even in oocytes devoid of cumulus cells. Culture of oocytes with the calcium channel blocker verapamil (concentrations ranging from 0.01 to 0.04 mM) blocked the progress of oocyte maturation beyond the stage of metaphase I. This block can be overcome by the mobilisation of intracellular calcium deposits after CPA treatment (100 nM). The microinjection of heparin (20 pl, 50.1 mg/;ml), the inhibitor of inositol triphosphate receptors, before CPA treatment prevented the acceleration of oocyte maturation. This indicates that CPA mobilises the release of calcium deposits through inositol trisphosphate receptors. On the other hand, the microinjection of procaine (20 pl, 200 nM) or the microinjection of ruthenium red (20 pl, 50 mM), both inhibitors of ryanodine receptors, did not prevent accelerated maturation in CPA-treated oocytes. If present in pig oocytes, ryanodine receptors evidently play no part in the liberation of calcium from intracellular stores after CPA treatment.

Participation of inositol trisphosphate and ryanodine receptors in Bufo arenarum oocyte activation

Zygote ◽  
2010 ◽  
Vol 19 (2) ◽  
pp. 171-180 ◽  
Author(s):  
M.T. Ajmat ◽  
F. Bonilla ◽  
L. Zelarayán ◽  
M.I. Bühler
Keyword(s):  
Calcium Release ◽  
Ryanodine Receptors ◽  
Inhibitory Effect ◽  
Ruthenium Red ◽  
Activation Process ◽  
Dependent Manner ◽  
Oocyte Activation ◽  
Relative Contribution ◽  
Morphological Criteria ◽  
Bufo Arenarum

SummaryCalcium is considered the most important second messenger at fertilization. Transient release from intracellular stores is modulated through both agonist-gated channels, IP3Rs and RyRs, which can be found individually or together depending on the oocyte species. Using the four commonly used compounds (thimerosal, caffeine, heparin and ruthenium red), we investigated the existence and interdependence of both IP3Rs and RyRs in mature Bufo arenarum oocytes. We found that caffeine, a well known specific RyRs agonist, was able to trigger oocyte activation in a dose-dependent manner. Microinjection of 10 mM caffeine showed 100% of oocytes exhibiting characteristic morphological criteria of egg activation. Ruthenium red, the specific RyR blocker, was able to inhibit oocyte activation induced either by sperm or caffeine. Our present findings provide the first reported evidence of the existence of RyR in frogs. We further explored the relationship between IP3Rs and RyRs in B. arenarum oocytes by exposing them to the agonists of one class after injecting a blocker of the other class of receptor. We found that thimerosal overcame the inhibitory effect of RyR on oocyte activation, indicating that IP3Rs function as independent receptors. In contrast, previous injection of heparin delayed caffeine-induced calcium release, revealing a relative dependence of RyRs on functional IP3Rs, probably through a CICR mechanism. Both receptors play a role in Ca2+ release mechanisms although their relative contribution to the activation process is unclear.

scholarly journals Agonist-dependent Phosphorylation of the Inositol 1,4,5-Trisphosphate Receptor

1999 ◽  
Vol 113 (6) ◽  
pp. 851-872 ◽  
Author(s):  
Andrew P. LeBeau ◽  
David I. Yule ◽  
Guy E. Groblewski ◽  
James Sneyd
Keyword(s):  
Acinar Cells ◽  
Calcium Oscillations ◽  
Pancreatic Acinar Cells ◽  
Ip3 Receptors ◽  
Ip3 Receptor ◽  
Open Probability ◽  
Probability Curve ◽  
Long Period ◽  
Inositol 1,4,5 Trisphosphate ◽  
S Period

The properties of inositol 1,4,5-trisphosphate (IP3)-dependent intracellular calcium oscillations in pancreatic acinar cells depend crucially on the agonist used to stimulate them. Acetylcholine or carbachol (CCh) cause high-frequency (10–12-s period) calcium oscillations that are superimposed on a raised baseline, while cholecystokinin (CCK) causes long-period (&gt;100-s period) baseline spiking. We show that physiological concentrations of CCK induce rapid phosphorylation of the IP3 receptor, which is not true of physiological concentrations of CCh. Based on this and other experimental data, we construct a mathematical model of agonist-specific intracellular calcium oscillations in pancreatic acinar cells. Model simulations agree with previous experimental work on the rates of activation and inactivation of the IP3 receptor by calcium (DuFour, J.-F., I.M. Arias, and T.J. Turner. 1997. J. Biol. Chem. 272:2675–2681), and reproduce both short-period, raised baseline oscillations, and long-period baseline spiking. The steady state open probability curve of the model IP3 receptor is an increasing function of calcium concentration, as found for type-III IP3 receptors by Hagar et al. (Hagar, R.E., A.D. Burgstahler, M.H. Nathanson, and B.E. Ehrlich. 1998. Nature. 396:81–84). We use the model to predict the effect of the removal of external calcium, and this prediction is confirmed experimentally. We also predict that, for type-III IP3 receptors, the steady state open probability curve will shift to lower calcium concentrations as the background IP3 concentration increases. We conclude that the differences between CCh- and CCK-induced calcium oscillations in pancreatic acinar cells can be explained by two principal mechanisms: (a) CCK causes more phosphorylation of the IP3 receptor than does CCh, and the phosphorylated receptor cannot pass calcium current; and (b) the rate of calcium ATPase pumping and the rate of calcium influx from the outside the cell are greater in the presence of CCh than in the presence of CCK.

cGMP abolishes agonist-induced [Ca2+]ioscillations in human bladder epithelial cells

2001 ◽  
Vol 281 (6) ◽  
pp. F1067-F1074 ◽  
Author(s):  
H. Y. Kwan ◽  
Y. Huang ◽  
S. K. Kong ◽  
X. Yao
Keyword(s):  
Epithelial Cells ◽  
Prolonged Exposure ◽  
Specific Inhibitor ◽  
Cytosolic Calcium ◽  
Inhibitory Effect ◽  
Calcium Oscillations ◽  
Protein Kinase G ◽  
Human Bladder ◽  
Inositol 1,4,5 Trisphosphate ◽  
Intracellular Ca

First published August 9, 2001; 10.1152/ajprenal.00031.2001.—Cytosolic calcium oscillations may permit cells to respond to information provided by increases in intracellular Ca2+ concentration ([Ca2+]i ) while avoiding prolonged exposure to constantly elevated [Ca2+]i. In this study, we demonstrated that agonists could induce Ca2+oscillations in human bladder epithelial cells. Application of 10 μM acetylcholine or 200 nM bradykinin triggered an initial Ca2+ transient that was followed by periodic [Ca2+]i oscillations. The oscillations did not depend on extracellular Ca2+. 8-Bromoguanosine 3′,5′-cyclic monophosphate abolished acetylcholine- or bradykinin-induced oscillations. Elevation of cellular cGMP by dipyridamole, an inhibitor of cGMP-specific phosphodiesterase, also terminated the [Ca2+]i oscillations. The inhibitory effect of cGMP could be reversed by KT-5823, a highly specific inhibitor of protein kinase G (PKG), suggesting that the action of cGMP was mediated by PKG. Comparison of the effect of cGMP with that of xestospongin C, an inhibitor of the inositol 1,4,5-trisphosphate (IP3) receptor, revealed similarities between the action of cGMP and xestospongin C. Therefore, it is likely that cGMP and PKG may target a signal transduction step(s) linked to IP3 receptor-mediated Ca2+ release.

Regulation of mouse egg activation: presence of ryanodine receptors and effects of microinjected ryanodine and cyclic ADP ribose on uninseminated and inseminated eggs

Development ◽  
1995 ◽  
Vol 121 (7) ◽  
pp. 2233-2244 ◽  
Author(s):  
T. Ayabe ◽  
G.S. Kopf ◽  
R.M. Schultz
Keyword(s):  
Ryanodine Receptor ◽  
Ryanodine Receptors ◽  
Meiotic Spindle ◽  
Egg Activation ◽  
Dependent Manner ◽  
Cyclic Adp Ribose ◽  
Inositol 1,4,5 Trisphosphate ◽  
Mouse Egg

Sperm-induced activation of mammalian eggs is associated with a transient increase in Ca2+ concentrations thought to be derived from inositol 1,4,5-trisphosphate-sensitive and -insensitive intracellular stores. Whereas the importance of inositol 1,4,5-trisphosphate-sensitive Ca2+ stores has been evaluated, the identity and role of inositol 1,4,5-trisphosphate-insensitive stores are poorly understood. To explore the role of the ryanodine-sensitive Ca2+ store, we first used reverse transcription-polymerase chain reaction to identify transcripts of the ryanodine receptor in eggs and determined that transcripts for the type 2 and 3 receptor were present. Immunoprecipitation of radioiodinated egg extracts with an antibody that recognizes both type 2 and 3 receptors detected specifically a band of Mr = 520,000. Immunolocalization of the receptor(s) using laser-scanning confocal microscopy revealed that the receptor(s) was uniformly distributed in the cortex of the germinal vesicle-intact oocyte, but became asymmetrically localized to the cortex in a region apposed to the meiotic spindle in the metaphase II-arrested egg; this asymmetrical localization developed by metaphase I. The role of the ryanodine receptor in mouse egg activation was examined by determining the effects of microinjected ryanodine or cyclic ADP ribose on endpoints of egg activation in either uninseminated or inseminated eggs. Ryanodine induced the conversion of the zona pellucida glycoprotein ZP2 to its postfertilization form ZP2f in a biphasic concentration-dependent manner; nanomolar concentrations stimulated this conversion, whereas micromolar concentrations had no stimulatory effect. Cyclic ADP ribose also promoted the ZP2 conversion, but with a hyperbolic concentration dependence. Neither of these compounds induced cell cycle resumption. Inhibiting the inositol 1,4,5-trisphosphate-sensitive Ca2+ store did not inhibit the ryanodine-induced ZP2 conversion and, reciprocally, inhibiting the ryanodine-sensitive Ca2+ store did not inhibit the inositol 1,4,5-trisphosphate-induced ZP2 conversion. Last, treatment of eggs under conditions that would block the release of Ca2+ from the ryanodine-sensitive store had no effect on any event of egg activation following fertilization. Results of these experiments suggest that although ryanodine receptors are present and functional, release of Ca2+ from this store is not essential for sperm-induced egg activation.

Involvement of inositol 1,4,5-trisphosphate-mediated Ca2+ release in early and late events of mouse egg activation

Development ◽  
1994 ◽  
Vol 120 (7) ◽  
pp. 1851-1859 ◽  
Author(s):  
Z. Xu ◽  
G.S. Kopf ◽  
R.M. Schultz
Keyword(s):  
Inhibitory Effect ◽  
Egg Activation ◽  
Dependent Manner ◽  
Ip3 Receptor ◽  
Concentration Dependent Manner ◽  
Post Translational Modifications ◽  
Inositol 1,4,5 Trisphosphate ◽  
Mammalian Eggs ◽  
Mouse Egg

Sperm-induced activation of mammalian eggs is associated with a transient increase in the concentration of intracellular Ca2+. The role of inositol 1,4,5-trisphosphate (IP3)-mediated release of Ca2+ from intracellular stores during mouse egg activation was examined in the present study by determining the effects of microinjected monoclonal antibody (mAb) 18A10, which binds to the IP3 receptor and inhibits IP3-induced Ca2+ release, on endpoints of egg activation following insemination. The antibody inhibited in a concentration-dependent manner the ZP2 to ZP2f conversion that is involved in the zona pellucida block to polyspermy, as well as the ZP2 to ZP2f conversion promoted by microinjected IP3 in non-inseminated eggs. As anticipated, inseminated eggs that had been microinjected with the antibody were polyspermic. In addition, the antibody inhibited the fertilization-associated decrease in H1 kinase activity and pronucleus formation, and the concentration dependence for inhibition of these events was similar to that observed for inhibiting the ZP2 to ZP2f conversion. Last, the antibody inhibited the fertilization-induced recruitment of maternal mRNAs and post-translational modifications of proteins. In each case, eggs microinjected with the mAb 4C11, which also binds to the IP3 receptor but does not inhibit IP3-induced Ca2+ release, had no inhibitory effect on fertilization and egg activation. Results of these studies suggest that IP3-mediated Ca2+ release is essential for both early and late events of mouse egg activation.

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