Vitrified-thawed mouse oocytes can be efficiently used to determine the oocyte activation potential of human sperm

Author(s):  
Davina Bonte
Zygote ◽  
2001 ◽  
Vol 9 (1) ◽  
pp. 89-95 ◽  
Author(s):  
Osamu Okitsu ◽  
Shuji Yamano ◽  
Toshihiro Aono

The aim of this study was to investigate whether bovine spermatozoa possess so-called sperm factor in the cytosolic fraction (CF) which activates bovine oocytes, and whether bovine oocytes matured in vitro are activated by microinjection of CF extracted from spermatozoa of other species. In the first experiment, bovine and human spermatozoa were microinjected into ooplasm of bovine oocytes matured in vitro. Secondly, CF from bovine and human spermatozoa were injected into bovine oocytes. In the third, CF from human spermatozoa was injected into human unfertilised oocytes obtained 18-20 h after clinical intracytoplasmic sperm injection (ICSI). We found that microinjection of bovine spermatozoa into bovine oocytes induced oocyte activation, as shown by resumption of meiosis and formation of a female pronucleus, at a significantly higher rate than the bovine sham injection (63.0% vs 43.0%; p < 0.05). On the other hand, there was no significant difference in activation rate between the human sperm injection (35.9%) and the human sham injection (22.9%). Furthermore, microinjection of bovine sperm CF into bovine oocytes induced oocyte activation at a significantly higher rate than the human CF injection or sham injection (75.9% vs 14.8%, 20.4%; p < 0.01). Formation of a single female pronucleus and second polar body extrusion was observed in 95.1% of activated oocytes after bovine sperm CF injection. When human sperm CF was injected into human unfertilised oocytes, the activation rate was significantly higher than following sham injection (76.9% vs 44.0%; p < 0.05). These results indicate the presence of sperm factor in bovine sperm CF which activate bovine oocytes, and suggest the possibility that sperm factor has species-specificity at least between bovine and human.


Zygote ◽  
1998 ◽  
Vol 6 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Daniel Szöllösi ◽  
Renata Czołowska ◽  
Ewa Borsuk ◽  
Maria S. Szöllösi ◽  
Pascale Debey

SummaryNuclei of embryonic red blood cells (e-RBC) from 12-day mouse fetuses are arrested in Go phase of the cell cycle and have low transcriptional activity. These nuclei were transferred with help of polyethylene glycol (PEG)-mediated fusion to parthenogenetically activated mouse oocytes and heterokaryons were analysed for nuclear structure and transcriptional activity. If fusion proceeded 25–45 min after oocyte activation, e-RBC nuclei were induced to nuclear envelope breakdown and partial chromatin condensation, followed by formation of nuclei structurally identical with pronuclei. These ‘pronuclei’, similar to egg (female) pronuclei, remained transcriptionally silent over several hours of in vitro culture. If fusion was performed 1 h or later (up to 7 h) after activation, the nuclear envelope of e-RBC nuclei remained intact and nuclear remodelling was less spectacular (slight chromatin decondensation, formation of nucleolus precursor bodies). These nuclei, however, reinforced polymerase-II-dependent transcription within a few hours of in vitro culture. Our present experiments, together with our previous work, demonstrate that nuclear envelope breakdown/maintenance are critical events for nuclear remodelling in activated mouse oocytes and that somatic dormant nuclei can be stimulated to renew transcription at a time when the female pronucleus remains transcriptionally silent.


2014 ◽  
Vol 21 (2) ◽  
pp. 157-168 ◽  
Author(s):  
Jessica Escoffier ◽  
Sandra Yassine ◽  
Hoi Chang Lee ◽  
Guillaume Martinez ◽  
Julie Delaroche ◽  
...  

1993 ◽  
Vol 104 (3) ◽  
pp. 861-872 ◽  
Author(s):  
M.S. Szollosi ◽  
J.Z. Kubiak ◽  
P. Debey ◽  
H. de Pennart ◽  
D. Szollosi ◽  
...  

Mouse oocyte activation is followed by a peculiar period during which the interphase network of microtubules does not form and the chromosomes remain condensed despite the inactivation of MPF. To evaluate the role of protein phosphorylation during this period, we studied the effects of the protein kinase inhibitor 6-dimethylaminopurine (6-DMAP) on fertilization and/or parthenogenetic activation of metaphase II-arrested mouse oocytes. 6-DMAP by itself does not induce the inactivation of histone H1 kinase in metaphase II-arrested oocytes, and does not influence the dynamics of histone H1 kinase inactivation during oocyte activation. However, 6-DMAP inhibits protein phosphorylation after oocyte activation. In addition, the phosphorylated form of some proteins disappear earlier in oocytes activated in the presence of 6-DMAP than in the activated control oocytes. This is correlated with the acceleration of some post-fertilization morphological events, such as sperm chromatin decondensation and its transient recondensation, formation of the interphase network of microtubules and pronuclear formation. In addition, numerous abnormalities could be observed: (1) the spindle rotation and polar body extrusion are inhibited; (2) the exchange of protamines into histones seems to be impaired, as judged by the morphology of DNA fibrils by electron microscopy; (3) the formation of a new nuclear envelope around the sperm chromatin proceeds prematurely, while recondensation is not yet completed. These observations suggest that the 6-DMAP-sensitive kinase(s) is (are) involved in the control of post-fertilization events such as the formation of the interphase network of microtubules, the remodelling of sperm chromatin and pronucleus formation.


2009 ◽  
Vol 21 (1) ◽  
pp. 217
Author(s):  
T. Wakai ◽  
N. Zhang ◽  
R. A. Fissore

Numerous studies have demonstrated that postovulatory aging of oocytes prior to fertilization has detrimental effects on oocyte quality and developmental competence. Oocyte aging is accompanied by abnormal oocyte activation and subsequent development, suggesting a disruption of Ca2+ oscillations after fertilization. The inositol 1,4,5-trisphosphate receptor type 1 (IP3R1) in mammals is responsible for the majority of Ca2+ release during fertilization (Miyazaki S et al. 1993 Dev. Biol.). Previously, we reported that phosphorylation of IP3R1 at an MPM-2 epitope may play an important role in facilitating the induction of Ca2+ oscillations at the MII stage (Lee B et al. 2006 Development), indicating that IP3R1 phosphorylation may be a good indicator of the health of the oocyte. However, few studies have investigated the alteration of the Ca2+ signaling and IP3R1 function associated with oocyte aging. On the other hand, a previous report showed that caffeine increased MPF activity and suppressed fragmentation after parthenogenetic activation of aged oocytes (Kikuchi K et al. 2000 Biol. Reprod.). Therefore, the purpose of the present study was to examine whether and how Ca2+ oscillatory activity changes during oocyte aging and to test if caffeine prevents the negative effects of oocyte aging. MII mouse oocytes were collected 14 h after hCG injection and cultured in vitro for 8, 24 or 48 h with or without caffeine (5 or 10 mm). Oocyte quality was assessed by the occurrence of spontaneous fragmentation, monitoring of Ca2+ oscillations after exposure to 10 mm strontium chloride, Western blot analysis of IP3R1 phosphorylation and immunostaining of IP3R1. In oocytes in vitro aged for 8 h, the duration of the first Ca2+ rise was significantly decreased compared with fresh MII oocytes, although this reduction was not observed in MII oocytes treated with 5 mm caffeine. The phosphorylation of IP3R1 at the MPM-2 epitope was slightly decreased during oocyte aging in both caffeine and noncaffeine treatment. Importantly, whereas IP3R1 in MII oocytes treated for 8 h with 5 mm caffeine displayed the typical cortical cluster organization, IP3R1 in aged oocytes without caffeine became dispersed in the cytoplasm. In addition, caffeine significantly suppressed the spontaneous fragmentation that is normally observed by 48 h of in vitro culture. These results suggest that the Ca2+ oscillatory activity is compromised during oocyte aging and caffeine prevents the loss of integrity of Ca2+ signaling possibly by keeping the cortical distribution of IP3R1.


2020 ◽  
Author(s):  
Omar Farhan Ammar ◽  
Therishnee Moodley

Abstract Objectives: Ca2+ is critical for normal oocyte activation and fertilization, and any alteration to the Ca2+ homeostasis may lead to failed fertilization or even cell death. It has been shown that intracellular Ca2+ is increased in bovine and human oocytes when cultured in vitro. Additionally, ATP sensitive potassium channels have been characterised recently in human and Xenopus oocytes. Glibenclamide a KATP channel blocker was shown to protect human oocytes from Ca+2 overloading via inhibition of plasmalemmal KATP channels. This research note aims to demonstrate the effects of oxidative stress and in vitro ageing on the intracellular Ca+2 and plasmalemmal membrane potential dynamics in cryopreserved metaphase II (MII) mouse oocytes. Also, this study aims to show if glibenclamide (a KATP channel blocker ) has a role in regulating intracellular Ca+2 and plasmalemmal membrane potential through KATP channels in cryopreserved metaphase II mouse oocytes.Results: our data did not show an increase in intracellular Ca2+ in untreated cryopreserved mouse oocytes loaded with Fluo-3 AM dye. However, an increase in the plasmalemmal membrane potential was noticed (hyperpolarization). Glibenclamide has shown no significant effect on Ca2+ and plasmalemmal membrane potential.


2007 ◽  
Vol 19 (1) ◽  
pp. 302
Author(s):  
C. Kani ◽  
M. Takenaka ◽  
T. Muneto ◽  
M. Yamamoto ◽  
T. Horiuchi

In vitro spermatogenesis can be applied to generate spermatids or spermatozoa and produce a genetically modified male germ line. Intracytoplasmic injection of the spermatids or spermatozoa is an important technique for effective production of offspring. The objective of this study is to evaluate oocyte-activation capacity of bovine spermatids or spermatozoa and to determine the effective activation treatment for in vitro development of bovine oocytes injected with round spermatids. Cryopreserved testicular spermatogenic cells and cauda epididymal spermatozoa obtained from a 1-year-old Japanese bull were used. In the first experiment, we injected bovine round (ROS) and elongated (ELS) spermatids, or testicular (TES) and cauda epididymal (CES) spermatozoa into mouse oocytes to examine their oocyte-activating capacity. The presence of pronuclei within whole-mounted oocytes was observed 4 h after injection. In the second experiment, we injected similar spermatids and spermatozoa into bovine oocytes without additional activation, and examined cleavage and blastocyst development. In the third experiment, bovine oocytes injected with ROS were activated with 7% ethanol or 5 �M ionomycin for 5 min (1 � Et or 1 � Iono) immediately after injection; some were further activated repeatedly at 3 h after injection (2 � Et or 2 � Iono), and some of these were subjected to 1.9 mM 6-dimethylaminopurine (DMAP) for 3 h after the second activation (2 � Et + DMAP or 2 � Iono + DMAP). Data were analyzed by the chi-square test in all experiments. The vast majority of bovine ROS failed to activate mouse oocytes (activation rate 10%). Activation rates of mouse oocytes injected with bovine ELS, TES, and CES were 61%, 75%, and 91%, respectively. The results suggest that oocyte-activation capacity is acquired during transformation from ROS to ELS. Cleavage and blastocyst rates of bovine oocytes injected with CES (59% and 19%, respectively) were significantly higher (P &lt; 0.05) than the rates obtained with injections of TES (37% and 9%) and ROS (5% and 0%) without additional activation. However, cleavage and blastocyst rates of bovine oocytes injected with ROS in the groups of 2 � Et + DMAP (80% and 19%) and 2 � Iono + DMAP (76% and 19%) were significantly higher (P &lt; 0.05) than those in the groups of 1 � and 2 � Et (37% and 2%, 59% and 4%), 1 � and 2 � Iono (10% and 7%, 22% and 4%), or those receiving a sham injection and activated with 2 � Iono + DMAP (43% and 4%). These results demonstrate that intracytoplasmic injection of ROS with repeated Et or Iono activation followed by DMAP treatment is more efficient than single or double Et or Iono activation.


Zygote ◽  
1996 ◽  
Vol 4 (04) ◽  
pp. 269-274 ◽  
Author(s):  
Isoji Sasagawa ◽  
R. Yanagimachi

SummaryIn the mouse, mature oocytes injected with prespermatozoal cell nuclei remain unactivated. Additional stimulation is needed to trigger oocyte activation leading to embryo development. We compared various electrical stimulations, treatment with cycloheximide alone or in combination with electrical stimulation, and injection of sperm-borne oocyte-activating factor (oscillogen) in terms of their oocyte activation and embryo development rates. Of all the treatments tested, a single electrical pulse (1.0 kV / cm, 128 μs) was the simplest, yet very effective, in allowing the development of the oocytes injected with spermatid nuclei.


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