Mitochondrial DNA replication is initiated at blastocyst formation in equine embryos

Hendriks, W. Karen, Colleoni, Silvia, Galli, Cesare, Paris, Damien B.B.P., Colenbrander, Ben, and Stout, Tom A.E. (2019) Mitochondrial DNA replication is initiated at blastocyst formation in equine embryos. Reproduction, Fertility and Development, 31 (3). pp. 570-578.

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Abstract

Intracytoplasmic sperm injection is the technique of choice for equine IVF and, in a research setting, 18–36% of injected oocytes develop to blastocysts. However, blastocyst development in clinical programs is lower, presumably due to a combination of variable oocyte quality (e.g. from old mares), suboptimal culture conditions and marginal fertility of some stallions. Furthermore, mitochondrial constitution appears to be critical to developmental competence, and both maternal aging and in vitro embryo production (IVEP) negatively affect mitochondrial number and function in murine and bovine embryos. The present study examined the onset of mitochondrial (mt) DNA replication in equine embryos and investigated whether IVEP affects the timing of this important event, or the expression of genes required for mtDNA replication (i.e. mitochondrial transcription factor (TFAM), mtDNA polymerase γ subunit B (mtPOLB) and single-stranded DNA binding protein (SSB)). We also investigated whether developmental arrest was associated with low mtDNA copy number. mtDNA copy number increased (P < 0.01) between the early and expanded blastocyst stages both in vivo and in vitro, whereas the mtDNA : total DNA ratio was higher in in vitro-produced embryos (P = 0.041). Mitochondrial replication was preceded by an increase in TFAM but, unexpectedly, not mtPOLB or SSB expression. There was no association between embryonic arrest and lower mtDNA copy numbers.

Item ID: 54214
Item Type: Article (Research - C1)
ISSN: 1448-5990
Keywords: assisted reproductive technology, blastocyst, embryo development, oocyte, gene expression, in vitro fertilisation, IVF, reproduction, RNA, horse
Copyright Information: Copyright © CSIRO 2019
Date Deposited: 03 Jan 2019 01:22
FoR Codes: 07 AGRICULTURAL AND VETERINARY SCIENCES > 0702 Animal Production > 070206 Animal Reproduction @ 25%
06 BIOLOGICAL SCIENCES > 0608 Zoology > 060803 Animal Developmental and Reproductive Biology @ 50%
06 BIOLOGICAL SCIENCES > 0604 Genetics > 060405 Gene Expression (incl Microarray and other genome-wide approaches) @ 25%
SEO Codes: 83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8303 Livestock Raising > 830306 Horses @ 50%
97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 25%
97 EXPANDING KNOWLEDGE > 970107 Expanding Knowledge in the Agricultural and Veterinary Sciences @ 25%
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