Maternal age and in vitro culture affect mitochondrial number and function in equine oocytes and embryos

Hendriks, W. Karin, Colleoni, Silvia, Galli, Cesare, Paris, Damien B.B.P., Colenbrander, Ben, Roelen, Bernard A.J., and Stout, Tom A.E. (2015) Maternal age and in vitro culture affect mitochondrial number and function in equine oocytes and embryos. Reproduction, Fertility and Development, 27 (6). pp. 957-968.

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Abstract

Advanced maternal age and in vitro embryo production (IVP) predispose to pregnancy loss in horses. We investigated whether mare age and IVP were associated with alterations in mitochondrial (mt) DNA copy number or function that could compromise oocyte and embryo development. Effects of mare age (<12 vs ≥12 years) on mtDNA copy number, ATP content and expression of genes involved in mitochondrial replication (mitochondrial transcription factor (TFAM), mtDNA polymerase γ subunit B (mtPOLB) and mitochondrial single-stranded DNA-binding protein (SSB)), energy production (ATP synthase-coupling factor 6, mitochondrial-like (ATP-synth_F6)) and oxygen free radical scavenging (glutathione peroxidase 3 (GPX3)) were investigated in oocytes before and after in vitro maturation (IVM), and in early embryos. Expression of TFAM, mtPOLB and ATP-synth-F6 declined after IVM (P < 0.05). However, maternal age did not affect oocyte ATP content or expression of genes involved in mitochondrial replication or function. Day 7 embryos from mares ≥12 years had fewer mtDNA copies (P = 0.01) and lower mtDNA : total DNA ratios (P < 0.01) than embryos from younger mares, indicating an effect not simply due to lower cell number. Day 8 IVP embryos had similar mtDNA copy numbers to Day 7 in vivo embryos, but higher mtPOLB (P = 0.013) and a tendency to reduced GPX3 expression (P = 0.09). The lower mtDNA number in embryos from older mares may compromise development, but could be an effect rather than cause of developmental retardation. The general down-regulation of genes involved in mitochondrial replication and function after IVM may compromise resulting embryos.

Item ID: 34510
Item Type: Article (Refereed Research - C1)
Keywords: horse, mitochondria, oocyte, embryo, maternal age, in vitro production, TFAM, mtPOLB, SSB, ATP-synth_F6, GPX, ATP, gene expression, mitochondrial quantity, mitochondrial replication
ISSN: 1448-5990
Date Deposited: 24 Jun 2015 04:49
FoR Codes: 07 AGRICULTURAL AND VETERINARY SCIENCES > 0702 Animal Production > 070206 Animal Reproduction @ 40%
06 BIOLOGICAL SCIENCES > 0601 Biochemistry and Cell Biology > 060103 Cell Development, Proliferation and Death @ 40%
06 BIOLOGICAL SCIENCES > 0604 Genetics > 060405 Gene Expression (incl Microarray and other genome-wide approaches) @ 20%
SEO Codes: 83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8303 Livestock Raising > 830306 Horses @ 50%
97 EXPANDING KNOWLEDGE > 970107 Expanding Knowledge in the Agricultural and Veterinary Sciences @ 30%
97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 20%
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