Effects of Maturation Conditions on Spindle Morphology in Porcine MII Oocytes

Ueno, Satoshi; Kurome, Mayuko; Ueda, Hideto; Tomii, Ryo; Hiruma, K.; Nagashima, Hiroshi

doi:10.1262/jrd.16091

Cited by 26 publications

(20 citation statements)

References 22 publications

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“…To examine female meiotic spindle features more broadly we fixed, stained and imaged eggs from ten organisms representing six different phyla (Figure 3A). In addition, published images of fixed female meiotic spindles from several organisms were included in the analysis (Figure 3D; [9,25–38]).…”

Section: Resultsmentioning

confidence: 99%

A Comparative Analysis of Spindle Morphometrics across Metazoans

et al. 2015

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Summary Cell division in all eukaryotes depends on function of the spindle, a microtubule-based structure that segregates chromosomes to generate daughter cells in mitosis or haploid gametes in meiosis. Spindle size adapts to changes in cell size and shape, which vary dramatically across species and within a multicellular organism, but the nature of scaling events and their underlying mechanisms are poorly understood. Cell size variations are most pronounced in early animal development, as egg diameters range from tens of microns up to millimeters across animal phyla, and decrease several orders of magnitude during rapid reductive divisions. During early embryogenesis in the model organisms X. laevis and C. elegans, the spindle scales with cell size [1,2], a phenomenon regulated by molecules that modulate microtubule dynamics [3–6], as well as by limiting cytoplasmic volume [7,8]. However, it is not known to what extent spindle scaling is conserved across organisms and among different cell types. Here we show that in a range of metazoan phyla, mitotic spindle length decreased with cell size across a ~30 fold difference in zygote size. Maximum spindle length varied, but linear spindle scaling occurred similarly in all species once embryonic cell diameter reduced to 140 μm. In contrast, we find that the female meiotic spindle does not scale as closely to egg size, adopting a more uniform size across species that likely reflects its specialized function. Our analysis reveals that spindle morphometrics change abruptly, within one cell cycle, at the transition from meiosis to mitosis in most animals.

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Section: Resultsmentioning

confidence: 99%

A Comparative Analysis of Spindle Morphometrics across Metazoans

et al. 2015

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“…However, similar to our results in bovines, in vitro matured porcine oocytes have been reported to possess significantly shorter meiotic spindles compared with their in vivo matured counterparts (Ueno et al . ). Both in cattle and pigs in vivo matured oocytes show higher developmental ability to the blastocyst stage than those matured in vitro (Nagashima et al .…”

Section: Discussionmentioning

confidence: 97%

Cytoskeletal and mitochondrial properties of bovine oocytes obtained by Ovum Pick‐Up: the effects of follicle stimulation and in vitro maturation

Somfai

Matoba

Inaba

et al. 2015

Animal Science Journal

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Follicle stimulation by follicular stimulating hormone (FSH) is known to improve developmental competence of bovine oocytes obtained by Ovum Pick-Up (OPU); however, the exact factors in oocytes affected by this treatment have remained unclear. We compared in vitro matured (IVM) oocytes obtained at the immature stage from cows by OPU either without or with stimulation with FSH (non-stimulated and stimulated OPU, respectively) to those obtained by superstimulation and in vivo maturation in terms of cytoskeleton morphology, mitochondrial distribution, intracellular adenosine triphosphate (ATP) content and H2 O2 levels at the metaphase-II stage and intracellular Ca(2+) levels after in vitro fertilization (IVF). Confocal microscopy after immunostaining revealed reduced size of the meiotic spindle, associated with increased tendencies of microfilament degradation and insufficient mitochondrial re-distribution in non-stimulated OPU-derived IVM oocytes compared with those collected by stimulated OPU, which in turn resembled in vivo matured oocytes. However, there was no difference in mitochondrial functions between oocytes obtained by stimulated or non-stimulated OPU in terms of ATP content, cytoplasmic H2 O2 levels, base Ca(2+) levels and the frequencies and amplitudes of Ca(2+) oscillations after IVF. Larger size of metaphase spindles in oocytes obtained by stimulated OPU may reflect and potentially contribute to their high developmental competence.

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“…In vivo derived mouse oocyte spindles are compact with focussed spindle poles, consist of acetylated microtubules and are significantly smaller in area compared with IVM mouse oocytes (Sanfins et al 2003). In the pig, IVM oocyte spindle length is decreased and the morphology is more rounded in appearance compared with the in vivo oocyte (Ueno et al 2005). In the present study, GSH-depleted bovine IVM oocytes displayed spindles with less focussed and wider poles, with a concomitant increase in spindle area, whereas GSH-OEt-treated COC oocytes showed an increase in spindle length without exhibiting significant changes in spindle area or chromosome alignment.…”

Section: Discussionmentioning

confidence: 98%

Bovine in vitro oocyte maturation as a model for manipulation of the γ-glutamyl cycle and intraoocyte glutathione

Curnow

Ryan

Saunders

et al. 2008

Reprod. Fertil. Dev.

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Glutathione (GSH) is the main non-enzymatic defence against oxidative stress and is a critical intracellular component required for oocyte maturation. In the present study, several modulators of intracellular GSH were assessed for their effect on the in vitro maturation (IVM) and intracellular GSH content of bovine metaphase (MII) oocytes. Of the five GSH modulators tested, only the cell-permeable GSH donor glutathione ethyl ester (GSH-OEt) significantly increased the GSH content of IVM MII oocytes in a concentration-dependent manner without adversely affecting oocyte maturation rate. The GSH level in IVM MII oocytes was greatly influenced by the presence or absence of cumulus cells and severely restricted when oocytes were cultured in the presence of buthionine sulfoximine (BSO), an inhibitor of GSH synthesis. The addition of GSH-OEt to cumulus-denuded or BSO-treated oocytes increased the GSH content of bovine MII oocytes. Supplementation of the maturation medium with bovine serum albumin (BSA) or fetal calf serum (FCS) affected the GSH content of IVM MII oocytes, with greater levels attained under BSA culture conditions. The addition of GSH-OEt to the maturation medium increased the GSH content of IVM MII oocytes, irrespective of protein source. Spindle morphology, as assessed by immunocytochemistry and confocal microscopy, displayed distinct alterations in response to changes in oocyte GSH levels. GSH depletion caused by BSO treatment tended to widen spindle poles and significantly increased spindle area. Supplementation of the IVM medium with GSH-OEt increased spindle length, but did not significantly alter spindle area or spindle morphology. GSH-OEt represents a novel oocyte-permeable and cumulus cell-independent approach for effective elevation of mammalian oocyte GSH levels.

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Effects of Maturation Conditions on Spindle Morphology in Porcine MII Oocytes

Cited by 26 publications

References 22 publications

A Comparative Analysis of Spindle Morphometrics across Metazoans

A Comparative Analysis of Spindle Morphometrics across Metazoans

Cytoskeletal and mitochondrial properties of bovine oocytes obtained by Ovum Pick‐Up: the effects of follicle stimulation and in vitro maturation

Bovine in vitro oocyte maturation as a model for manipulation of the γ-glutamyl cycle and intraoocyte glutathione

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