title: Replication Errors Made During Oogenesis Lead to Detectable De Novo mtDNA Mutations in Zebrafish Oocytes with a Low mtDNA Copy Number.
abstract: Of all pathogenic mitochondrial DNA (mtDNA) mutations in humans, ∼25% is de novo, although the occurrence in oocytes has never been directly assessed. We used next-generation sequencing to detect point mutations directly in the mtDNA of 3-15 individual mature oocytes and three somatic tissues from eight zebrafish females. Various statistical and biological filters allowed reliable detection of de novo variants with heteroplasmy ≥1.5%. In total, we detected 38 de novo base substitutions, but no insertions or deletions. These 38 de novo mutations were present in 19 of 103 mature oocytes, indicating that ∼20% of the mature oocytes carry at least one de novo mutation with heteroplasmy ≥1.5%. This frequency of de novo mutations is close to that deducted from the reported error rate of polymerase gamma, the mitochondrial replication enzyme, implying that mtDNA replication errors made during oogenesis are a likely explanation. Substantial variation in the mutation prevalence among mature oocytes can be explained by the highly variable mtDNA copy number, since we previously reported that ∼20% of the primordial germ cells have a mtDNA copy number of ≤73 and would lead to detectable mutation loads. In conclusion, replication errors made during oogenesis are an important source of de novo mtDNA base substitutions and their location and heteroplasmy level determine their significance.
authors: Department of Genetics and Cell Biology, Clinical Genomics Unit, School for Oncology and Developmental Biology, Maastricht University, 6200 MD, The Netherlands.
authors: Auke B C
authors: http://orcid.org/0000-0001-5034-9743
authors: AB
authors: Otten
authors: Department of Genetics and Cell Biology, Clinical Genomics Unit, School for Oncology and Developmental Biology, Maastricht University, 6200 MD, The Netherlands.
authors: Alphons P M
authors: AP
authors: Stassen
authors: Maastricht Centre for Systems Biology, Maastricht University, 6200 MD, The Netherlands.
authors: Michiel
authors: http://orcid.org/0000-0002-4472-7119
authors: M
authors: Adriaens
authors: Maastricht Centre for Systems Biology, Maastricht University, 6200 MD, The Netherlands.
authors: Mike
authors: M
authors: Gerards
authors: Department of Genetics and Cell Biology, Clinical Genomics Unit, School for Oncology and Developmental Biology, Maastricht University, 6200 MD, The Netherlands.
authors: Richard G J
authors: RG
authors: Dohmen
authors: Department of Genetics and Cell Biology, Clinical Genomics Unit, School for Oncology and Developmental Biology, Maastricht University, 6200 MD, The Netherlands.
authors: Adriana J
authors: AJ
authors: Timmer
authors: Department of Genetics and Cell Biology, Clinical Genomics Unit, School for Oncology and Developmental Biology, Maastricht University, 6200 MD, The Netherlands.
authors: Sabina J V
authors: SJ
authors: Vanherle
authors: Department of Genetics and Cell Biology, Clinical Genomics Unit, School for Oncology and Developmental Biology, Maastricht University, 6200 MD, The Netherlands.
authors: Rick
authors: R
authors: Kamps
authors: Department of Genetics and Cell Biology, Clinical Genomics Unit, School for Oncology and Developmental Biology, Maastricht University, 6200 MD, The Netherlands.
authors: Iris B W
authors: IB
authors: Boesten
authors: Department of Genetics and Cell Biology, Clinical Genomics Unit, School for Oncology and Developmental Biology, Maastricht University, 6200 MD, The Netherlands.
authors: Jo M
authors: JM
authors: Vanoevelen
authors: Laboratory of Organogenesis and Regeneration, Interdisciplinary Cluster for Applied Genoproteomics Research, Univérsité de Liège, 4000, Belgium.
authors: Marc
authors: M
authors: Muller
authors: Department of Genetics and Cell Biology, Clinical Genomics Unit, School for Oncology and Developmental Biology, Maastricht University, 6200 MD, The Netherlands bert.smeets@maastrichtuniversity.nl.|Maastricht Centre for Systems Biology, Maastricht University, 6200 MD, The Netherlands.
authors: Hubert J M
authors: HJ
authors: Smeets
mesh_terms: D000818:Animals; D004261:DNA Replication; D004272:DNA, Mitochondrial / Q000235:genetics*; D005260:Female; D018628:Gene Dosage; D009154:Mutation; D059645:Mutation Rate; D009865:Oocytes / Q000166:cytology / Q000378:metabolism*; D009866:Oogenesis; D015027:Zebrafish
chemical_list: D004272:DNA, Mitochondrial
keywords: de novo mutations; mitochondrial DNA; next-generation sequencing; oogenesis; zebrafish