title: Dynamic changes in mitochondrial DNA, distribution and activity within cat oocytes during folliculogenesis.
abstract: Mitochondria play fundamental roles during oocyte development. The accumulation and spatial redistribution of these energy-producing organelles have been linked to the developmental competence of mammalian oocytes. Here, we assessed the copy number, distribution and activity of mitochondria within cat oocytes during folliculogenesis. In Experiment 1, oocytes were recovered from primordial (n = 152), primary (112), secondary (95), early (131), small (118), antral (86) and advanced antral (5) stages follicles, and mitochondria DNA extracted and quantified using qPCR. In Experiment 2, oocytes from pre-antral (n = 44), early antral (n = 66), small antral (n = 59), antral (n = 41) and advanced antral (n = 21) follicles were isolated and stained with CMXRos MitoTracker dye to assess mitochondrial distribution pattern and activity levels. Oocyte's mitochondria DNA (mtDNA) copy numbers gradually increased as folliculogenesis progressed, with a significant shift at the small antral stage (0.5 to <1 mm in diameter). The location of mitochondria gradually shifted from a homogeneous distribution throughout the cytoplasm in pre-antral oocytes to a pericortical concentration in the advanced antral stage. Quantification of CMXRos fluorescent intensity revealed a progressive increase in mitochondrial activity in oocytes from the pre-antral to the large antral follicles. Taken together, these findings demonstrated that cat oocytes undergo dynamic changes in mitochondrial copy number, distribution and activity during folliculogenesis. These significant modifications to this crucial cytoplasmic organelle are likely associated with the acquisition of developmental competency by cat oocytes.
authors.affiliation: Center for Species Survival, Smithsonian Conservation Biology Institute, National Zoological Park, Front Royal, VA, USA.
authors.forename: N
authors.initials: N
authors.lastname: Songsasen
authors.affiliation: Center for Species Survival, Smithsonian Conservation Biology Institute, National Zoological Park, Front Royal, VA, USA.
authors.forename: L H
authors.initials: LH
authors.lastname: Henson
authors.affiliation: Zoological Park Organization, Bangkok, Thailand.|Department of Obstetrics, Gynaecology and Reproduction, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand.
authors.forename: W
authors.initials: W
authors.lastname: Tipkantha
authors.affiliation: Center for Species Survival, Smithsonian Conservation Biology Institute, National Zoological Park, Front Royal, VA, USA.
authors.forename: C
authors.initials: C
authors.lastname: Thongkittidilok
authors.affiliation: Department of Biology, Dickinson College, Carlisle, PA, USA.
authors.forename: J H
authors.initials: JH
authors.lastname: Henson
authors.affiliation: Department of Obstetrics, Gynaecology and Reproduction, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand.
authors.forename: K
authors.initials: K
authors.lastname: Chatdarong
authors.affiliation: Center for Species Survival, Smithsonian Conservation Biology Institute, National Zoological Park, Front Royal, VA, USA.
authors.forename: P
authors.initials: P
authors.lastname: Comizzoli
mesh_terms: D000818:Animals; D002415:Cats / Q000502:physiology*; D003593:Cytoplasm; D056915:DNA Copy Number Variations; D004272:DNA, Mitochondrial / Q000235:genetics*; D047108:Embryonic Development; D005260:Female; D009865:Oocytes / Q000502:physiology*; D009866:Oogenesis / Q000235:genetics*; D006080:Ovarian Follicle / Q000502:physiology*
chemical_list: D004272:DNA, Mitochondrial
keywords: cat oocyte; follicle development; mitochondria copy number; mitochondrial distribution