Suppression of chromosome condensation during meiotic maturation induces parthenogenetic development of mouse oocytes

Development ◽  
1988 ◽  
Vol 104 (1) ◽  
pp. 97-103 ◽  
Author(s):  
H.J. Clarke ◽  
J. Rossant ◽  
Y. Masui
Keyword(s):  
Protein Synthesis ◽  
Blastocyst Stage ◽  
Chromosome Condensation ◽  
Meiotic Maturation ◽  
Dibutyryl Cyclic Amp ◽  
Developmental Arrest ◽  
Mouse Oocytes ◽  
Parthenogenetic Development ◽  
No Activation ◽  
Metaphase I

Mouse oocytes at metaphase I were treated with puromycin, which caused the chromosomes to become decondensed within an interphase nucleus. When the oocytes were allowed to resume protein synthesis, they returned to metaphase within 8–10 h and neither synthesized DNA nor cleaved, indicating that they had not been parthenogenetically activated by the puromycin treatment. However, when dibutyryl cyclic AMP was added to the medium after protein synthesis resumed, the oocytes remained in interphase. These oocytes maintained in interphase began DNA synthesis beginning 20 h after puromycin withdrawal, even though no activation stimulus had been given to them. After transfer to the oviducts of foster mothers, the oocytes could develop to the blastocyst stage. These results indicate that oocytes whose chromosomes were decondensed by puromycin treatment at metaphase I could begin parthenogenetic development in the absence of an activating stimulus, provided that they were prevented from returning to metaphase. In contrast, when the puromycin-treated oocytes were allowed to return to metaphase, they became developmentally arrested at the end of maturation. This suggests that the mechanism responsible for the developmental arrest of mature oocytes at metaphase II depends on cytoplasmic conditions that cause chromosome condensation to the metaphase state.

Meiotic maturation of mouse oocytes in vitro: association of newly synthesized proteins with condensing chromosomes

1976 ◽  
Vol 20 (3) ◽  
pp. 549-568 ◽  
Author(s):  
P.M. Wassarman ◽  
G.E. Letourneau
Keyword(s):  
Protein Synthesis ◽  
Mammalian Species ◽  
Germinal Vesicle ◽  
Chromosome Condensation ◽  
Intracellular Distribution ◽  
Meiotic Maturation ◽  
Meiotic Progression ◽  
Mouse Oocytes

The nature, intracellular distribution, and role of proteins synthesized during meiotic maturation of mouse oocytes in vitro have been examined. Proteins synthesized during the initial stages of maturation are concentrated within the nucleus (germinal vesicle) and become intimately associated with the condensing chromosomes. Inhibition of protein synthesis during this period does not prevent germinal vesicle dissolution or chromosome condensation, but meiotic progression is blocked reversibly at the circular bivalent stage. A protein is synthesized during meiotic maturation of the mouse oocyte which exhibits several of the characteristics of the very lysine-rich histone, FI; this and other histones are phosphorylated during the initial stages of maturation. These results are discussed in relation to studies of meiotic maturation of oocytes from non-mammalian species and chromosome condensation in both oocytes and mitotic cells.

Meiotic maturation of mouse oocytes in vitro: protein synthesis in nucleate and anucleate oocyte fragments

1978 ◽  
Vol 30 (1) ◽  
pp. 251-264
Author(s):  
R.M. Schultz ◽  
G.E. Letourneau ◽  
P.M. Wassarman
Keyword(s):  
Protein Synthesis ◽  
Meiotic Prophase ◽  
Cytochalasin B ◽  
Meiotic Maturation ◽  
In Vitro Protein Synthesis ◽  
Mammalian Oocyte ◽  
Mouse Oocytes ◽  
Meiotic Competence ◽  
Vitro Protein

Nucleate and anucleate fragments of mouse oocytes have been isolated following treatment of fully grown oocytes with cytochalasin B. The nucleate oocyte fragments resume meiosis in vitro, progressing from dictyate of the first meiotic prophase to metaphase II (‘meiotic maturation’), and exhibit all of the changes in protein synthesis normally associated with meiotic maturation of mouse oocytes. The anucleate oocyte fragments also undergo certain of the changes in protein synthesis associated with meiotic maturation, despite the absence of nuclear progression. These results suggest that the acquisition of meiotic competence (i.e. the ability to undergo meiotic maturation) during growth of the mammalian oocyte is due to changes in the quality, rather than the quantity, of cytoplasm and that the reprogramming of protein synthesis during meiotic maturation is directed by RNA templates already present in the cytoplasm. The behaviour of anucleate oocyte fragments is discussed in terms of the proposed role for nucleoplasm in the initiation of changes in protein synthesis during meiotic maturation of mouse oocytes.

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.

Meiotic maturation of mouse oocytes in vitro: inhibition of maturation at specific stages of nuclear progression

1976 ◽  
Vol 22 (3) ◽  
pp. 531-545
Author(s):  
P.M. Wassarman ◽  
W.J. Josefowicz ◽  
G.E. Letourneau
Keyword(s):  
Cyclic Amp ◽  
Cytochalasin B ◽  
Polar Body ◽  
Germinal Vesicle ◽  
Meiotic Maturation ◽  
Dibutyryl Cyclic Amp ◽  
Germinal Vesicle Breakdown ◽  
Mouse Oocytes ◽  
First Polar Body

In vitro studies of meiotic maturation of mouse oocytes have been carried out in the presence of several drugs. The individual steps of nuclear progression, including dissolution of the nuclear (germinal vesicle) membrane, condensation of dictyate chromatin into compact bivalents, formation of the first metaphase spindle, and extrusion of the first polar body, are each susceptible to one or more of these drugs. Germinal vesicle breakdown, the initial morphological feature characteristic of meiotic maturation, is inhibited by dibutyryl cyclic AMP. However, even in the presence of dibutyryl cyclic AMP, the nuclear membrane becomes extremely convoluted and condensation of chromatin is initiated but aborts at a stage short of compact bivalents. Germinal vesicle breakdown and chromatin condensation take place in an apparently normal manner in the presence of puromycin, Colcemid, or cytochalasin B. Nuclear progression is blocked at the circular bivalent stage when oocytes are cultured continuously in the presence of puromycin or Colcemid, whereas oocytes cultured in the presence of cytochalasin B proceed to the first meiotic metaphase, form an apparently normal spindle, and arrest. Emission of a polar body is inhibited by all of these drugs. The inhibitory effects of these drugs on meiotic maturation are reversible to varying degrees dependent upon the duration of exposure to the drug and upon the nature of the drug. These studies suggest that dissolution of the mouse oocyte's germinal vesicle and condensation of chromatin are not dependent upon concomitant protein synthesis or upon microtubules. On the other hand, the complete condensation of chromatin into compact bivalents apparently requires breakdown of the germinal vesicle. Failure of homologous chromosomes to separate after normal alignment on the meiotic spindle in the presence of cytochalasin B suggest that microfilaments may be involved in nuclear progression at this stage of maturation. Cytokinesis, in the form of polar body formation, is blocked when any one of the earlier events of maturation fails to take place.

Immunofluorescent anti-tubulin staining of spindles during meiotic maturation of mouse oocytes in vitro

1978 ◽  
Vol 29 (1) ◽  
pp. 171-188
Author(s):  
P.M. Wassarman ◽  
K. Fujiwara
Keyword(s):  
Polar Body ◽  
Immunofluorescent Staining ◽  
Meiotic Maturation ◽  
Cytoplasmic Bridge ◽  
Specific Staining ◽  
Mouse Oocytes ◽  
Maturation In Vitro ◽  
Reproducible Manner ◽  
Metaphase I

Immunofluorescent anti-tubulin staining has been used to follow nuclear progression from dictyate to metaphase II during meiotic maturation of mouse oocytes in vitro. Antibody directed against tubulin isolated from sea-urchin eggs decorates the metaphase I and metaphase II spindles, as well as the cytoplasmic bridge, midbody, and polar body of the maturing mouse oocytes. Changes in the tubulin-specific staining pattern during meiotic maturation in vitro take place in a highly reproducible manner. Oocytes exposed continuously to cytochalasin B arrest at metaphase I and display a spindle which by immunofluorescent staining is virtually indistinguishable from the spindle of untreated oocytes.

Progression of mouse oocytes from metaphase I to metaphase II is inhibited by fusion with G2 cells

Zygote ◽  
2000 ◽  
Vol 8 (2) ◽  
pp. 145-151 ◽  
Author(s):  
Joanna Grabarek ◽  
Magdalena Zernicka-Goetz
Keyword(s):  
Chromosome Condensation ◽  
Factor Activity ◽  
Premature Chromosome Condensation ◽  
Mouse Oocytes ◽  
M Phase ◽  
G2 Cells ◽  
Cytostatic Factor ◽  
Metaphase Ii Oocytes ◽  
Metaphase I

We show that in contrast to metaphase II oocytes, metaphase I oocytes cannot be activated by fusion with the zygote. Fusion of metaphase I oocytes with G2 zygotes was followed by premature chromosome condensation, with 60% of the hybrids becoming arrested at metaphase I, the remainder progressing and arresting at metaphase II. Hybrids of metaphase I oocytes and M-phase zygotes underwent accelerated maturation, but all arrested at metaphase II. In both cases the arrest could be overcome by treatment with the parthenogenetic activators ethanol and cycloheximide. We discuss these findings in relation to the possibility that the metaphase I oocyte contains cytostatic factor activity that is activated by its zygotic partner. Alternatively, the G2 zygote may provide an inhibitor of anaphase, normally never present in the metaphase I oocyte and which is absent from the M-phase zygote.

Tamoxifen-induced alterations in meiotic maturation and cytogenetic abnormalities in mouse oocytes and 1-cell zygotes

Zygote ◽  
2001 ◽  
Vol 9 (2) ◽  
pp. 97-104 ◽  
Author(s):  
Steve N. London ◽  
John B. Mailhes
Keyword(s):  
Calcium Antagonist ◽  
Tamoxifen Treatment ◽  
Meiotic Maturation ◽  
Oral Gavage ◽  
Camp Phosphodiesterase ◽  
Cytogenetic Abnormalities ◽  
Female Mice ◽  
Mouse Oocytes ◽  
Oocyte Meiotic Maturation ◽  
Metaphase I

Alterations in the rate of oocyte meiotic maturation (OM) and the timing of the metaphase-anaphase transition may predispose oocytes to premature centromere separation (PCS) and aneuploidy. Tamoxifen has the potential for perturbing the rate of OM since it can function as a calcium antagonist by binding to calmodulin and inhibiting the formation of a calcium-calmodulin complex which is needed for activating calmodulin-dependent cAMP phosphodiesterase and initiating OM. The objective of this study was to test the hypothesis that tamoxifen alters the rate of OM and predisposes oocytes to PCS and aneuploidy. Different does of tamoxifen were administered by oral gavage to female mice preovulation. Metaphase II oocyte and 1-cell zygote chromosomes were C-banded and cytogenetically analysed. Tamoxifen treatment resulted in a modest, but significant (p < 0.05), increase in oocytes with PCS. Similar frequencies of hyperploidy and oocytes with unpaired, single chromatids (SC) were found. Metaphase I, diploid and premature anaphase (PA) oocytes were not detected. Hyperploidy, polyploidy, PCS, PA and SC were not detected in zygotes. These data indicate that the levels of tamoxifen-induced PCS found in mouse oocytes did not predispose zygotes to aneuploidy. Tamoxifen did, however, reduce the proportion of females exhibiting oestrus.

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