Meiotic spindle assembly in cytoplasmic extracts of Spisula solidissima oocytes

1993 ◽  
Vol 51 ◽  
pp. 180-181
Author(s):  
Robert E. Palazzo ◽  
Eugeni Vaisberg ◽  
Richard W. Cole ◽  
Conly L. Rieder
Keyword(s):  
Polarized Light ◽  
Germinal Vesicle ◽  
Spindle Assembly ◽  
Meiotic Spindle ◽  
Spisula Solidissima ◽  
Animal Cells ◽  
Parthenogenetic Activation ◽  
Unique System ◽  
Tubulin Antibodies

Critical for karyokinesis in animal cells, is the assembly of a spindle-chromosome-aster complex which serves as the force-generation system for chromosome segregation. Spisula solidissima oocytes offer a unique system for the study of spindle assembly since they can be obtained in large quantities, are naturally synchronized in the cell cycle and can be induced to assemble meiotic spindles within 15 min after parthenogenetic activation. Oocytes contain a large nucleus [germinal vesicle (GV)] and are arrested at the G2/M border of meiosis I. No centrosomes or asters have been observed in oocytes at this stage by either electron microscopy or fluorescence microscopy using anti-tubulin antibodies. Observation of live oocytes with polarized light microscopy revealed that within 4-6 min after parthenogenetic activation, asters appeared and invaded the GV as it breaks down (GVBD). 15 min after activation a complete bipolar meiotic spindle was observed.As a first step towards the development of an in vitro biochemical reconstitution system for the study of spindle assembly, concentrated lysates were prepared at various times following parthenogenetic activation and analyzed by phase-contrast microscopy.

Overheating is detrimental to meiotic spindles within in vitro matured human oocytes

Zygote ◽  
2004 ◽  
Vol 12 (1) ◽  
pp. 65-70 ◽  
Author(s):  
Xiao-Fang Sun ◽  
Wei-Hua Wang ◽  
David L. Keefe
Keyword(s):  
High Temperature ◽  
Light Microscope ◽  
Polarized Light ◽  
Germinal Vesicle ◽  
Meiotic Spindle ◽  
Human Oocytes ◽  
Living State ◽  
Meiotic Spindles ◽  
Metaphase I

The present study was designed to examine the effects of overheating on meiotic spindle morphology within in vitro matured human oocytes using a polarized light microscope (Polscope). Immature human oocytes at either germinal vesicle or metaphase I stage were cultured in vitro for 24–36 h until they reached metaphase II (M-II) stage. After maturation, oocytes at M-II stage were imaged in the living state with the Polscope at 37, 38, 39 and 40 °C for up to 20 min. After heating, oocytes were returned to 37 °C and then imaged for another 20 min at 37 °C. The microtubules in the spindles were quantified by their maximum retardance, which represents the amount of microtubules. Spindles were intact at 37 °C during 40 min of examination and their maximum retardance (1.72–1.79) did not change significantly during imaging. More microtubules were formed in the spindles heated to 38 °C and the maximum retardance was increased from 1.77 before heating to 1.95 at 20 min after heating. By contrast, spindles started to disassemble when the temperature was increased to 39 °C for 10 min (maximum retardance was reduced from 1.76 to 1.65) or 40 °C for 1 min (maximum retardance was reduced from 1.75 to 1.5). At the end of heating (20 min), fewer microtubules were present in the spindles and the maximum retardance was reduced to 0.8 and 0.78 in the oocytes heated to 39 °C and 40 °C, respectively. Heating to 40 °C also induced spindles to relocate in the cytoplasm in some oocytes. After the temperature was returned to 37 °C, microtubules were repolymerized to form spindles, but the spindles were not reconstituted completely compared with the spindles imaged before heating. These results indicate that spindles in human eggs are sensitive to high temperature. Moreover, maintenance of an in vitro manipulation temperature of 37 °C is crucial for normal spindle morphology.

scholarly journals Dynamic Changes of pStat3 are Involved in Meiotic Spindle Assembly in Mouse Oocytes

2020 ◽  
Author(s):  
Seiki Haraguchi ◽  
Mitsumi Ikeda ◽  
Satoshi Akagi ◽  
Yuji Hirao
Keyword(s):  
Oocyte Maturation ◽  
Spindle Assembly ◽  
Meiotic Spindle ◽  
Dual Function ◽  
Dependent Manner ◽  
Vitro Fertilization ◽  
Spindle Poles ◽  
Activation Of Transcription ◽  
Transcription 3

The signal transducer and activator of transcription 3 (Stat3) is activated in response to the phosphorylation of Y705 (pStat3) and has the dual function of signal transduction and activation of transcription. Our previous study suggested that pStat3 is functional during oocyte maturation when transcription is silenced. Therefore, we speculated that pStat3 may have another function. Immunocytochemical analysis revealed that pStat3 emerges at the microtubule asters and spindle and then localizes at the spindle poles concomitant with a Pericentrin during mouse oocyte maturation. When we examined conditionally knocked out Stat3−/− oocytes, we detected Stat3 and pStat3 proteins. The localization of the pStat3 was the same as that of Stat3+/+ oocytes, and the oocyte maturation proceeded normally, suggesting that pStat3 was still functioning. The oocytes were treated either with the Stat3 specific inhibitors, Stattic and BP-1-102, or anti-pStat3 antibody injection. This caused significant abnormal spindle assembly and chromosome mis-location in a dose-dependent manner, in which the pStat3 was either negative or localized improperly. Moreover, development of pre-implantation stage embryos derived from inhibitor-treated oocytes was also hampered significantly after in vitro fertilization. These findings indicate a novel function of pStat3 involved in spindle assembly.

scholarly journals Acentrosomal spindle assembly and stability in C. elegans oocytes requires a kinesin-12 non-motor microtubule interaction domain

2021 ◽  
Author(s):  
Ian Daniel Wolff ◽  
Jeremy Alden Hollis ◽  
Sarah Marie Wignall
Keyword(s):  
Adaptor Protein ◽  
Direct Interaction ◽  
Spindle Assembly ◽  
Meiotic Spindle ◽  
Interaction Domain ◽  
Microtubule Binding ◽  
C Elegans ◽  
Insight Into

During the meiotic divisions in oocytes, microtubules are sorted and organized by motor proteins to generate a bipolar spindle in the absence of centrosomes. In most organisms, kinesin-5 family members crosslink and slide microtubules to generate outward force that promotes acentrosomal spindle bipolarity. However, the mechanistic basis for how other kinesin families act on acentrosomal spindles has not been explored. We investigated this question in C. elegans oocytes, where kinesin-5 is not required to generate outward force. Instead, the kinesin-12 family motor KLP-18 performs this function. KLP-18 acts with adaptor protein MESP-1 (meiotic spindle 1) to sort microtubule minus ends to the periphery of a microtubule array, where they coalesce into spindle poles. If either of these proteins is depleted, outward sorting of microtubules is lost and minus ends converge to form a monoaster. Here we use a combination of in vitro biochemical assays and in vivo mutant analysis to provide insight into the mechanism by which these proteins collaborate to promote acentrosomal spindle assembly. We identify a microtubule binding site on the C-terminal stalk of KLP-18 and demonstrate that a direct interaction between the KLP-18 stalk and MESP-1 activates non-motor microtubule binding. We also provide evidence that this C-terminal domain is required for KLP-18 activity during spindle assembly and show that KLP-18 is continuously required to maintain spindle bipolarity. This study thus provides new insight into the construction and maintenance of the oocyte acentrosomal spindle as well as into kinesin-12 mechanism and regulation.

79 DEVELOPMENTAL COMPETENCE OF OVINE OOCYTES VITRIFIED AT GERMINAL VESICLE STAGE: IN VITRO FERTILIZATION, PARTHENOGENETIC ACTIVATION, AND SOMATIC CELL NUCLEAR TRANSFER

2011 ◽  
Vol 23 (1) ◽  
pp. 145
Author(s):  
A. R. Moawad ◽  
I. Choi ◽  
J. Zhu ◽  
K. H. S. Campbell
Keyword(s):  
Somatic Cell ◽  
Somatic Cell Nuclear Transfer ◽  
Nuclear Transfer ◽  
Germinal Vesicle ◽  
Developmental Competence ◽  
Control Groups ◽  
High Frequencies ◽  
Parthenogenetic Activation ◽  
And Control

Oocyte cryopreservation represents an important development in the field of assisted reproductive technologies. This study investigated the effects of vitrification on spindle morphology following subsequent in vitro maturation (IVM), cleavage, and development following IVF and parthenogenetic activation. The developmental competence of ovine oocytes vitrified at the germinal vesicle (GV) stage, matured, and used as cytoplast recipients for somatic cell nuclear transfer (SCNT) was also determined. Cumulus–oocyte complexes obtained at slaughter were divided into 3 groups: 1) untreated (control), 2) toxicity (exposed to vitrification solutions without freezing), and 3) vitrified (2008 Reprod. Fertil. Dev. 20, 122). At 24 hpm (hours post onset of maturation), oocytes were subjected to 1) immunostaining, 2) IVF, or 3) activation by 2 different protocols [calcium ionophore, cycloheximide, and cytochalasin B (CA+CHX/CB), or strontium and CB (Sr/CB)]. The SCNT was performed as previously described (2010 Reprod. Fertil. Dev. 22, 1000–1014). Presumptive zygotes were cultured in vitro for 7 days. No significant differences (P > 0.05; chi-square) were observed in the frequencies of oocytes with normal spindle configuration between vitrified, toxicity, and control groups (50.0, 54.9, and 70.4%, respectively). Cleavage 24, 48 hpi, and morula development (5 days pi) were significantly decreased (P < 0.01) in the vitrified group (17.3, 42.9, and 36.4%) compared with toxicity (47.0, 85.3, and 60.7%) and control (68.9, 89.7, and 62.6%) groups. Blastocyst development significantly decreased (P < 0.01) in the vitrified group (12.3%) compared with toxicity (42.7%) and control (40.4%) groups. Based on cleaved embryos, no significant difference was observed between vitrified and control groups (29.4 v. 45.1%). Post-activation, cleavage 24 hpa (hours post-activation, 6.2 v. 3.8%) and 48 hpa (28.4 v. 27.5%) was significantly lower (P < 0.05) in vitrified oocytes activated by (CA+CHX/CB and Sr/CB) than other groups. No blastocyst developed from vitrified oocytes activated by CA+CHX/CB; however, 3.8% developed from Sr/CB oocytes. This was significantly (P < 0.05) lower than toxicity and control (20.0 and 27.3%) groups. Following SCNT, high frequencies of enucleation (99%) and fusion (98%) were achieved in vitrified and control groups. Cleavage 24 and 48 hpa significantly decreased (P < 0.05) in the vitrified group (31.0 and 48.0%) compared with the control (55.1 and 85.0%). No significant differences were observed in morula (38.0 v. 46.7%) and blastocyst (13.0 v. 23.4%) development. The proportion of cleaved embryos that developed to blastocyst stages was similar in both groups (27.0%). No significant differences (t-test) were observed in total cell numbers, apoptotic nuclei, and proportion of diploid embryos. In conclusion, ovine oocytes vitrified at GV stage can be matured, fertilized, and develop in vitro with high developmental potential. Strontium can be used effectively for activation of vitrified/thawed ovine oocytes. Vitrified/thawed ovine oocytes were used successfully for the first time as recipient cytoplasts for SCNT and produced high frequencies of good-quality blastocyst stage embryos.

Microtubule and microfilament organization in immature, in vitro matured and in vitro fertilized prepubertal goat oocytes

Zygote ◽  
2005 ◽  
Vol 13 (2) ◽  
pp. 155-165 ◽  
Author(s):  
Esther Velilla ◽  
Elisabet Rodríguez-Gonzalez ◽  
Francesca Vidal ◽  
Maria-Teresa Paramio
Keyword(s):  
Laser Scanning ◽  
Polar Body ◽  
Germinal Vesicle ◽  
Fluorescein Isothiocyanate ◽  
Confocal Laser Scanning Microscope ◽  
Meiotic Spindle ◽  
Confocal Laser ◽  
Cortical Region ◽  
Microtubule Networks

The aim of our study was to analyse the cytoskeletal organization of prepubertal goat oocytes. Microtubule and microfilament organization during in vitro maturation of prepubertal and adult goat oocytes and presumptive zygotes of in vitro matured–in vitro fertilized (IVM-IVF) prepubertal goat oocytes were analysed. Oocytes were matured in M-199 with hormones and serum and inseminated with frozen-thawed spermatozoa. Oocytes and presumptive zygotes were treated with anti-α-tubulin antibody and fluorescein isothiocyanate (FITC)-labelled goat anti-mouse antibody to stain the microtubules. Microfilaments were localized by means of phalloidin 5 μg/ml conjugated with fluorescein isothiocyanate (FITC-phalloidin). DNA was stained with propidium iodide. Stained oocytes were observed under a confocal laser scanning microscope. At the germinal vesicle nuclear stage, microfilaments were distributed at the cortex of the oocytes. After in vitro maturation, 91.7% of metaphase II (MII) oocytes from adult goats displayed microfilaments in the cortex and within the polar body and were characterized by the presence of a microfilament thickening at the cortical region over the meiotic spindle. In prepubertal goat MII oocytes only 5.7% of oocytes displayed microfilaments at the cortex and within the polar body. After insemination, most of the zygotes displayed microfilaments distributed at the cortex. An undefined microtubular network was observed in adult and prepubertal goat oocytes at the germinal vesicle stage. After in vitro maturation, 100% of MII oocytes from adult goats displayed microtubules on the meiotic spindle and within the polar body. This pattern of distribution was observed in 71.6% of prepubertal goat oocytes. Undefined microtubule networks were present in most of the zygotes analysed. In conclusion, cytoskeletal differences were found between prepubertal and adult goat MII oocytes. Furthermore, most of the zygotes from IVM-IVF prepubertal goat oocytes displayed cytoskeletal anomalies.

scholarly journals Spindle assembly in the absence of chromosomes in mouse oocytes

Reproduction ◽  
2007 ◽  
Vol 134 (6) ◽  
pp. 731-738 ◽  
Author(s):  
Ji-Wen Yang ◽  
Zi-Li Lei ◽  
Yi-Liang Miao ◽  
Jun-Cheng Huang ◽  
Li-Hong Shi ◽  
...  
Keyword(s):  
Germinal Vesicle ◽  
Spindle Assembly ◽  
Meiotic Maturation ◽  
Bipolar Spindle ◽  
Microtubule Organizing Centers ◽  
Mouse Oocytes ◽  
Inactive Form ◽  
Different Shapes ◽  
Metaphase I

This study was carried out to investigate the contributions of chromosomes to spindle assembly in mouse oocytes. We generated two groups of cytoplasts (holo- and hemi-cytoplasts) by enucleation of germinal vesicle (GV), metaphase I (MI), and metaphase II (MII) oocytes using micromanipulation technology. After in vitro culture for 18 h, spindles with different shapes (bi-, mono-, or multipolar) formed in most of these cytoplasts except in hemi-GV cytoplasts. Two or more spindles were observed in most of holo-GV, holo-MI, and holo-MII cytoplasts (76.1, 77.0, and 83.7% respectively). However, the proportions of hemi-MI and hemi-MII cytoplasts with multiple sets of spindles decreased to 17.6 and 20.7% respectively. A single bipolar spindle was observed in each sham-operated oocyte generated by removing different volumes of cytoplasm from the oocytes and keeping nuclei intact. Localization of γ-tubulin showed that microtubule organizing centers (MTOCs) were dispersed at each pole of the multiple sets of spindles formed in holo-cytoplasts. However, most of the MTOCs aggregated at the two poles of the bipolar spindle in sham-operated oocytes. Our results demonstrate that chromosomes are not essential for initiating spindle assembly but for directing distinct MTOCs to aggregate to form a bipolar spindle. Some factors of undetermined nature may pre-exist in an inactive form in GV-stage ooplasm, serving as initiators of spindle assembly upon their activation. Moreover, GV materials released into the cytoplasm may facilitate spindle assembly in normal meiotic maturation.

scholarly journals Dynamic Changes in pStat3 Are Involved in Meiotic Spindle Assembly in Mouse Oocytes

2020 ◽  
Vol 21 (4) ◽  
pp. 1220
Author(s):  
Seiki Haraguchi ◽  
Mitsumi Ikeda ◽  
Satoshi Akagi ◽  
Yuji Hirao
Keyword(s):  
Oocyte Maturation ◽  
Spindle Assembly ◽  
Meiotic Spindle ◽  
Dual Function ◽  
Dependent Manner ◽  
Vitro Fertilization ◽  
Mouse Oocytes ◽  
Spindle Poles ◽  
Transcription 3

The signal transducer and activator of transcription 3 (Stat3) is activated upon phosphorylation at Y705 (pStat3) and serves the dual function of signal transduction and transcription activation. Our previous study suggested that pStat3 is functional during oocyte maturation when transcription is silenced. Therefore, we speculated that pStat3 serves other functions. Immunocytochemical analysis revealed that pStat3 emerges at microtubule asters and spindle and is subsequently localized at the spindle poles along with pericentrin during mouse oocyte maturation. Both Stat3 and pStat3 proteins were detected in conditionally knocked out Stat3−/− mouse oocytes. pStat3 localization was the same in Stat3+/+ and Stat3−/− oocytes, and oocyte maturation proceeded normally, suggesting that pStat3 was still functional. Furthermore, the treatment of oocytes with the Stat3-specific inhibitors stattic and BP-1-102 or anti-pStat3 antibody led to significantly abnormal spindle assembly and chromosome mislocation in a dose-dependent manner, and pStat3 was either absent or improperly localized in these oocytes. Moreover, the development of pre-implantation stage embryos derived from inhibitor-treated oocytes was significantly hampered following in vitro fertilization. These findings indicate a novel function of pStat3 in spindle assembly.

Sign in / Sign up

Export Citation Format

Share Document