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Fleischmann Z, Cote-L'Heureux A, Franco M, Oreshkov S, Annis S, Khrapko M, Aidlen D, Popadin K, Woods DC, Tilly JL, Khrapko K. Reanalysis of mtDNA mutations of human primordial germ cells (PGCs) reveals NUMT contamination and suggests that selection in PGCs may be positive. Mitochondrion 2024; 74:101817. [PMID: 37914096 DOI: 10.1016/j.mito.2023.10.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 10/19/2023] [Accepted: 10/28/2023] [Indexed: 11/03/2023]
Abstract
The resilience of the mitochondrial genome (mtDNA) to a high mutational pressure depends, in part, on negative purifying selection in the germline. A paradigm in the field has been that such selection, at least in part, takes place in primordial germ cells (PGCs). Specifically, Floros et al. (Nature Cell Biology 20: 144-51) reported an increase in the synonymity of mtDNA mutations (a sign of purifying selection) between early-stage and late-stage PGCs. We re-analyzed Floros' et al. data and determined that their mutational dataset was significantly contaminated with single nucleotide variants (SNVs) derived from a nuclear sequence of mtDNA origin (NUMT) located on chromosome 5. Contamination was caused by co-amplification of the NUMT sequence by cross-specific PCR primers. Importantly, when we removed NUMT-derived SNVs, the evidence of purifying selection was abolished. In addition to bulk PGCs, Floros et al. reported the analysis of single-cell late-stage PGCs, which were amplified with different sets of PCR primers that cannot amplify the NUMT sequence. Accordingly, there were no NUMT-derived SNVs among single PGC mutations. Interestingly, single PGC mutations show adecreaseof synonymity with increased intracellular mutant fraction. More specifically, nonsynonymous mutations show faster intracellular genetic drift towards higher mutant fraction than synonymous ones. This pattern is incompatible with predominantly negative selection. This suggests that germline selection of mtDNA mutations is a complex phenomenon and that the part of this process that takes place in PGCs may be predominantly positive. However counterintuitive, positive germline selection of detrimental mtDNA mutations has been reported previously andpotentially may be evolutionarily advantageous.
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Affiliation(s)
- Zoë Fleischmann
- Department of Biology, Northeastern University, Boston, MA, USA
| | | | - Melissa Franco
- Department of Biology, Northeastern University, Boston, MA, USA
| | - Sergey Oreshkov
- Center for Mitochondrial Functional Genomics, Institute of Living Systems, Immanuel Kant Baltic Federal University, 236040 Kaliningrad, Russia
| | - Sofia Annis
- Department of Biology, Northeastern University, Boston, MA, USA
| | - Mark Khrapko
- Department of Biology, Northeastern University, Boston, MA, USA
| | - Dylan Aidlen
- Department of Biology, Northeastern University, Boston, MA, USA
| | - Konstantin Popadin
- School of Life Sciences, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland; Center for Mitochondrial Functional Genomics, Institute of Living Systems, Immanuel Kant Baltic Federal University, 236040 Kaliningrad, Russia
| | - Dori C Woods
- Department of Biology, Northeastern University, Boston, MA, USA
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Singhi A, Chen T, Madison R, Bhardwaj N, Jin D, Fleischmann Z, Newberg J, Moore J, Frampton G, Hegde P, Fabrizio D, He J, Schrock A, Ebot E, Sokol E. 1300P Exploration of a novel HRD signature (HRDsig) as a biomarker of first line FOLFIRINOX benefit in metastatic pancreatic cancer. Ann Oncol 2022. [DOI: 10.1016/j.annonc.2022.07.1432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Alberico H, Fleischmann Z, Bobbitt T, Takai Y, Ishihara O, Seki H, Anderson RA, Telfer EE, Woods DC, Tilly JL. Workflow Optimization for Identification of Female Germline or Oogonial Stem Cells in Human Ovarian Cortex Using Single-Cell RNA Sequence Analysis. Stem Cells 2022; 40:523-536. [PMID: 35263439 PMCID: PMC9199849 DOI: 10.1093/stmcls/sxac015] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 02/15/2022] [Indexed: 11/16/2022]
Abstract
In 2004, the identification of female germline or oogonial stem cells (OSCs) that can support post-natal oogenesis in ovaries of adult mice sparked a major paradigm shift in reproductive biology. Although these findings have been independently verified, and further extended to include identification of OSCs in adult ovaries of many species ranging from pigs and cows to non-human primates and humans, a recent study rooted in single-cell RNA sequence analysis (scRNA-seq) of adult human ovarian cortical tissue claimed that OSCs do not exist, and that other groups working with OSCs following isolation by magnetic-assisted or fluorescence-activated cell sorting have mistaken perivascular cells (PVCs) for germ cells. Here we report that rare germ lineage cells with a gene expression profile matched to OSCs but distinct from that of other cells, including oocytes and PVCs, can be identified in adult human ovarian cortical tissue by scRNA-seq after optimization of analytical workflow parameters. Deeper cell-by-cell expression profiling also uncovered evidence of germ cells undergoing meiosis-I in adult human ovaries. Lastly, we show that, if not properly controlled for, PVCs can be inadvertently isolated during flow cytometry protocols designed to sort OSCs because of inherently high cellular autofluorescence. However, human PVCs and human germ cells segregate into distinct clusters following scRNA-seq due to non-overlapping gene expression profiles, which would preclude the mistaken identification and use of PVCs as OSCs during functional characterization studies.
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Affiliation(s)
- Hannah Alberico
- Laboratory of Aging and Infertility Research, Department of Biology, Northeastern University, Boston, MA 02115, USA
| | - Zoë Fleischmann
- Laboratory of Aging and Infertility Research, Department of Biology, Northeastern University, Boston, MA 02115, USA
| | - Tyler Bobbitt
- Laboratory of Aging and Infertility Research, Department of Biology, Northeastern University, Boston, MA 02115, USA
| | - Yasushi Takai
- Department of Obstetrics and Gynecology, Saitama Medical Center, Saitama Medical University, Saitama 350-0495, Japan
| | - Osamu Ishihara
- Department of Obstetrics and Gynecology, Saitama Medical Center, Saitama Medical University, Saitama 350-0495, Japan
| | - Hiroyuki Seki
- Department of Obstetrics and Gynecology, Saitama Medical Center, Saitama Medical University, Saitama 350-0495, Japan
| | - Richard A Anderson
- MRC Centre for Reproductive Health, Queens Medical Research Institute, University of Edinburgh, Edinburgh EH14 1DJ, UK
| | - Evelyn E Telfer
- Institute of Cell Biology, University of Edinburgh, Edinburgh EH14 1DJ, UK
| | - Dori C Woods
- Laboratory of Aging and Infertility Research, Department of Biology, Northeastern University, Boston, MA 02115, USA
| | - Jonathan L Tilly
- Laboratory of Aging and Infertility Research, Department of Biology, Northeastern University, Boston, MA 02115, USA
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Annis S, Fleischmann Z, Logan R, Mullin-Bernstein Z, Franco M, Saürich J, Tilly JL, Woods DC, Khrapko K. LUCS: a high-resolution nucleic acid sequencing tool for accurate long-read analysis of individual DNA molecules. Aging (Albany NY) 2020; 12:7603-7613. [PMID: 32345770 PMCID: PMC7202536 DOI: 10.18632/aging.103171] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 04/21/2020] [Indexed: 12/26/2022]
Abstract
Nucleic acid sequence analyses are fundamental to all aspects of biological research, spanning aging, mitochondrial DNA (mtDNA) and cancer, as well as microbial and viral evolution. Over the past several years, significant improvements in DNA sequencing, including consensus sequence analysis, have proven invaluable for high-throughput studies. However, all current DNA sequencing platforms have limited utility for studies of complex mixtures or of individual long molecules, the latter of which is crucial to understanding evolution and consequences of single nucleotide variants and their combinations. Here we report a new technology termed LUCS (Long-molecule UMI-driven Consensus Sequencing), in which reads from third-generation sequencing are aggregated by unique molecular identifiers (UMIs) specific for each individual DNA molecule. This enables in-silico reconstruction of highly accurate consensus reads of each DNA molecule independent of other molecules in the sample. Additionally, use of two UMIs enables detection of artificial recombinants (chimeras). As proof of concept, we show that application of LUCS to assessment of mitochondrial genomes in complex mixtures from single cells was associated with an error rate of 1X10-4 errors/nucleotide. Thus, LUCS represents a major step forward in DNA sequencing that offers high-throughput capacity and high-accuracy reads in studies of long DNA templates and nucleotide variants in heterogenous samples.
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Affiliation(s)
- Sofia Annis
- Department of Biology, Laboratory of Aging and Infertility Research, Northeastern University, Boston, MA 02115, USA
| | - Zoë Fleischmann
- Department of Biology, Laboratory of Aging and Infertility Research, Northeastern University, Boston, MA 02115, USA
| | - Robert Logan
- Department of Biology, Laboratory of Aging and Infertility Research, Northeastern University, Boston, MA 02115, USA
| | - Zachary Mullin-Bernstein
- Department of Biology, Laboratory of Aging and Infertility Research, Northeastern University, Boston, MA 02115, USA
| | - Melissa Franco
- Department of Biology, Laboratory of Aging and Infertility Research, Northeastern University, Boston, MA 02115, USA
| | - Josefin Saürich
- Department of Biology, Laboratory of Aging and Infertility Research, Northeastern University, Boston, MA 02115, USA.,On leave under a Student Exchange Program from the Institut für Pflanzengenetik, Leibniz Universität Hannover, Hannover D-30419, Germany
| | - Jonathan L Tilly
- Department of Biology, Laboratory of Aging and Infertility Research, Northeastern University, Boston, MA 02115, USA
| | - Dori C Woods
- Department of Biology, Laboratory of Aging and Infertility Research, Northeastern University, Boston, MA 02115, USA
| | - Konstantin Khrapko
- Department of Biology, Laboratory of Aging and Infertility Research, Northeastern University, Boston, MA 02115, USA
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