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The activity and copy number of mitochondrial DNA in ovine oocytes throughout oogenesis in vivo and during oocyte maturation in vitro.

ABSTRACT: Mitochondria are responsible for the production of ATP, which drives cellular metabolic and biosynthetic processes. This is the first study to quantify the mtDNA copy number across all stages of oogenesis in a large monovulatory species, it includes assessment of the activity of mitochondria in germinal vesicle (GV) and metaphase II (MII) oocytes through JC1 staining. Primordial to early antral follicles (n = 249) were isolated from the sheep ovarian cortex following digestion at 37°C for 1 h and all oocytes were disaggregated from their somatic cells. Germinal vesicle oocytes (n = 133) were aspirated from 3- to 5-mm diameter antral follicles, and mature MII oocytes (n = 71) were generated following in vitro maturation (IVM). The mtDNA copy number in each oocyte was quantified using real-time PCR and showed a progressive, but variable increase in the amount of mtDNA in oocytes from primordial follicles (605 ± 205, n = 8) to mature MII oocytes (744 633 ± 115 799, n = 13; P < 0.05). Mitochondrial activity (P > 0.05) was not altered during meiotic progression from GV to MII during IVM. The observed increase in the mtDNA copy number across oogenesis reflects the changing ATP demands needed to orchestrate cytoskeletal and cytoplasmic reorganization during oocyte growth and maturation and the need to fuel the resumption of meiosis in mature oocytes following the pre-ovulatory gonadotrophin surge.

SUBMITTER: Cotterill M

PROVIDER: S-EPMC3690804 | biostudies-literature | 2013 Jul

REPOSITORIES: biostudies-literature

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The activity and copy number of mitochondrial DNA in ovine oocytes throughout oogenesis in vivo and during oocyte maturation in vitro.

Cotterill Matthew M Harris Sarah E SE Collado Fernandez Esther E Lu Jianping J Huntriss John D JD Campbell Bruce K BK Picton Helen M HM

Molecular human reproduction 20130305 7

Mitochondria are responsible for the production of ATP, which drives cellular metabolic and biosynthetic processes. This is the first study to quantify the mtDNA copy number across all stages of oogenesis in a large monovulatory species, it includes assessment of the activity of mitochondria in germinal vesicle (GV) and metaphase II (MII) oocytes through JC1 staining. Primordial to early antral follicles (n = 249) were isolated from the sheep ovarian cortex following digestion at 37°C for 1 h an ...[more]

PMID: 23468533

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Project description:BackgroundHeavy metal cadmium (Cd) is a widespread environmental contaminant with a potential toxicity that might negatively affect female reproduction and fertility. It has been reported that Cd exposure impaired the quality of oocytes and led to a defective maturation and fertilization, through oxidative stress induction. Resveratrol (Res) is a natural polyphenol with strong antioxidant properties that exhibited protective role in preventing oocyte redox homeostasis disruption and quality decline. Here, we explored whether the addition of Res to in vitro maturation (IVM) medium might act as a protection against Cd-induced toxicity on ovine oocyte maturation and fertilization. Firstly, we evaluated the effect of supplementing IVM medium with two different Res concentrations (1 and 2 μmol/L) on nuclear maturation and fertilization of oocytes matured under CdCl2 (2 μmol/L) exposure. Therefore, the concentration of 1 μmol/L Res was selected to analyse the effects of this compound on intracellular ROS levels, mitochondrial (mt) distribution and activity, chromatin configuration, cytoskeleton morphology, cortical granules (CGs) distribution and mRNA expression of genes associated with cellular response to oxidative stress (i.e. SIRT1, SOD 1, GPX1, GSR, CAT) in Cd-exposed in vitro matured oocytes.ResultsWe found that 1 μmol/L Res restored the reduced oocyte meiotic competence induced by Cd exposure as well as, Res sustained oocyte ability to be normally fertilized and decreased polyspermic fertilization at both tested concentrations. Moreover, we demonstrated that 1 μmol/L Res mitigated Cd-induced alterations of oocyte cytoplasmic maturation by reducing reactive oxygen species (ROS) accumulation, preventing mt dysfunction, maintaining the correct meiotic spindle and cortical F-actin assembly and the normal cortical granule distribution as well as up-regulating SIRT1, SOD1 and GPX1 genes.ConclusionsTaken together, our findings highlighted the beneficial influence exerted by Res in preventing Cd-induced disturbance of nuclear and cytoplasmic maturation and subsequent fertilization in ovine oocytes. Res treatment may help to establish defence strategies counteracting Cd-induced toxicity on the female gamete.

Dataset Information

The activity and copy number of mitochondrial DNA in ovine oocytes throughout oogenesis in vivo and during oocyte maturation in vitro.

Publications

The activity and copy number of mitochondrial DNA in ovine oocytes throughout oogenesis in vivo and during oocyte maturation in vitro.

Similar Datasets

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