1
|
Choy YMM, Walter GM, Mirth CK, Sgrò CM. Within-population plastic responses to combined thermal-nutritional stress differ from those in response to single stressors, and are genetically independent across traits in both males and females. J Evol Biol 2024; 37:717-731. [PMID: 38757509 DOI: 10.1093/jeb/voae061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 03/25/2024] [Accepted: 05/16/2024] [Indexed: 05/18/2024]
Abstract
Phenotypic plasticity helps animals to buffer the effects of increasing thermal and nutritional stress created by climate change. Plastic responses to single and combined stressors can vary among genetically diverged populations. However, less is known about how plasticity in response to combined stress varies among individuals within a population or whether such variation changes across life-history traits. This is important because individual variation within populations shapes population-level responses to environmental change. Here, we used isogenic lines of Drosophila melanogaster to assess the plasticity of egg-to-adult viability and sex-specific body size for combinations of 2 temperatures (25 °C or 28 °C) and 3 diets (standard diet, low caloric diet, or low protein:carbohydrate ratio diet). Our results reveal substantial within-population genetic variation in plasticity for egg-to-adult viability and wing size in response to combined thermal-nutritional stress. This genetic variation in plasticity was a result of cross-environment genetic correlations that were often < 1 for both traits, as well as changes in the expression of genetic variation across environments for egg-to-adult viability. Cross-sex genetic correlations for body size were weaker when the sexes were reared in different conditions, suggesting that the genetic basis of traits may change with the environment. Furthermore, our results suggest that plasticity in egg-to-adult viability is genetically independent from plasticity in body size. Importantly, plasticity in response to diet and temperature individually differed from plastic shifts in response to diet and temperature in combination. By quantifying plasticity and the expression of genetic variance in response to combined stress across traits, our study reveals the complexity of animal responses to environmental change, and the need for a more nuanced understanding of the potential for populations to adapt to ongoing climate change.
Collapse
Affiliation(s)
- Yeuk Man Movis Choy
- School of Biological Sciences, Monash University, Wellington Rd, Clayton, Melbourne, Victoria, Australia
| | - Greg M Walter
- School of Biological Sciences, Monash University, Wellington Rd, Clayton, Melbourne, Victoria, Australia
| | - Christen K Mirth
- School of Biological Sciences, Monash University, Wellington Rd, Clayton, Melbourne, Victoria, Australia
| | - Carla M Sgrò
- School of Biological Sciences, Monash University, Wellington Rd, Clayton, Melbourne, Victoria, Australia
| |
Collapse
|
2
|
Li N, Flanagan BA, Edmands S. The role of mitochondria in sex- and age-specific gene expression in a species without sex chromosomes. Proc Natl Acad Sci U S A 2024; 121:e2321267121. [PMID: 38838014 PMCID: PMC11181141 DOI: 10.1073/pnas.2321267121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2023] [Accepted: 05/13/2024] [Indexed: 06/07/2024] Open
Abstract
Mitochondria perform an array of functions, many of which involve interactions with gene products encoded by the nucleus. These mitochondrial functions, particularly those involving energy production, can be expected to differ between sexes and across ages. Here, we measured mitochondrial effects on sex- and age-specific gene expression in parental and reciprocal F1 hybrids between allopatric populations of Tigriopus californicus with over 20% mitochondrial DNA divergence. Because the species lacks sex chromosomes, sex-biased mitochondrial effects are not confounded by the effects of sex chromosomes. Results revealed pervasive sex differences in mitochondrial effects, including effects on energetics and aging involving nuclear interactions throughout the genome. Using single-individual RNA sequencing, sex differences were found to explain more than 80% of the variance in gene expression. Males had higher expression of mitochondrial genes and mitochondrially targeted proteins (MTPs) involved in oxidative phosphorylation (OXPHOS), while females had elevated expression of non-OXPHOS MTPs, indicating strongly sex-dimorphic energy metabolism at the whole organism level. Comparison of reciprocal F1 hybrids allowed insights into the nature of mito-nuclear interactions, showing both mitochondrial effects on nuclear expression, and nuclear effects on mitochondrial expression. While based on a small set of crosses, sex-specific increases in mitochondrial expression with age were associated with longer life. Network analyses identified nuclear components of strong mito-nuclear interactions and found them to be sexually dimorphic. These results highlight the profound impact of mitochondria and mito-nuclear interactions on sex- and age-specific gene expression.
Collapse
Affiliation(s)
- Ning Li
- Department of Biological Sciences, University of Southern California, Los Angeles, CA90089
| | - Ben A. Flanagan
- Department of Biological Sciences, University of Southern California, Los Angeles, CA90089
| | - Suzanne Edmands
- Department of Biological Sciences, University of Southern California, Los Angeles, CA90089
| |
Collapse
|
3
|
Edmands S. Mother's Curse effects on lifespan and aging. FRONTIERS IN AGING 2024; 5:1361396. [PMID: 38523670 PMCID: PMC10957651 DOI: 10.3389/fragi.2024.1361396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/25/2023] [Accepted: 02/20/2024] [Indexed: 03/26/2024]
Abstract
The Mother's Curse hypothesis posits that mothers curse their sons with harmful mitochondria, because maternal mitochondrial inheritance makes selection blind to mitochondrial mutations that harm only males. As a result, mitochondrial function may be evolutionarily optimized for females. This is an attractive explanation for ubiquitous sex differences in lifespan and aging, given the prevalence of maternal mitochondrial inheritance and the established relationship between mitochondria and aging. This review outlines patterns expected under the hypothesis, and traits most likely to be affected, chiefly those that are sexually dimorphic and energy intensive. A survey of the literature shows that evidence for Mother's Curse is limited to a few taxonomic groups, with the strongest support coming from experimental crosses in Drosophila. Much of the evidence comes from studies of fertility, which is expected to be particularly vulnerable to male-harming mitochondrial mutations, but studies of lifespan and aging also show evidence of Mother's Curse effects. Despite some very compelling studies supporting the hypothesis, the evidence is quite patchy overall, with contradictory results even found for the same traits in the same taxa. Reasons for this scarcity of evidence are discussed, including nuclear compensation, factors opposing male-specific mutation load, effects of interspecific hybridization, context dependency and demographic effects. Mother's Curse effects may indeed contribute to sex differences, but the complexity of other contributing factors make Mother's Curse a poor general predictor of sex-specific lifespan and aging.
Collapse
Affiliation(s)
- Suzanne Edmands
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States
| |
Collapse
|
4
|
Iverson ENK. Conservation Mitonuclear Replacement: Facilitated mitochondrial adaptation for a changing world. Evol Appl 2024; 17:e13642. [PMID: 38468713 PMCID: PMC10925831 DOI: 10.1111/eva.13642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 12/29/2023] [Accepted: 01/03/2024] [Indexed: 03/13/2024] Open
Abstract
Most species will not be able to migrate fast enough to cope with climate change, nor evolve quickly enough with current levels of genetic variation. Exacerbating the problem are anthropogenic influences on adaptive potential, including the prevention of gene flow through habitat fragmentation and the erosion of genetic diversity in small, bottlenecked populations. Facilitated adaptation, or assisted evolution, offers a way to augment adaptive genetic variation via artificial selection, induced hybridization, or genetic engineering. One key source of genetic variation, particularly for climatic adaptation, are the core metabolic genes encoded by the mitochondrial genome. These genes influence environmental tolerance to heat, drought, and hypoxia, but must interact intimately and co-evolve with a suite of important nuclear genes. These coadapted mitonuclear genes form some of the important reproductive barriers between species. Mitochondrial genomes can and do introgress between species in an adaptive manner, and they may co-introgress with nuclear genes important for maintaining mitonuclear compatibility. Managers should consider the relevance of mitonuclear genetic variability in conservation decision-making, including as a tool for facilitating adaptation. I propose a novel technique dubbed Conservation Mitonuclear Replacement (CmNR), which entails replacing the core metabolic machinery of a threatened species-the mitochondrial genome and key nuclear loci-with those from a closely related species or a divergent population, which may be better-adapted to climatic changes or carry a lower genetic load. The most feasible route to CmNR is to combine CRISPR-based nuclear genetic editing with mitochondrial replacement and assisted reproductive technologies. This method preserves much of an organism's phenotype and could allow populations to persist in the wild when no other suitable conservation options exist. The technique could be particularly important on mountaintops, where rising temperatures threaten an alarming number of species with almost certain extinction in the next century.
Collapse
Affiliation(s)
- Erik N. K. Iverson
- Department of Integrative BiologyThe University of Texas at AustinAustinTexasUSA
| |
Collapse
|
5
|
Li N, Flanagan BA, Edmands S. The role of mitochondria in sex- and age-specific gene expression in a species without sex chromosomes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.08.570893. [PMID: 38106076 PMCID: PMC10723445 DOI: 10.1101/2023.12.08.570893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Mitochondria perform an array of functions, many of which involve interactions with gene products encoded by the nucleus. These mitochondrial functions, particularly those involving energy production, can be expected to differ between sexes and across ages. Here we measured mitochondrial effects on sex- and age-specific gene expression in parental and reciprocal F1 hybrids between allopatric populations of Tigriopus californicus with over 20% mitochondrial DNA divergence. Because the species lacks sex chromosomes, sex-biased mitochondrial effects are not confounded by the effects of sex chromosomes. Using single-individual RNA sequencing, sex differences were found to explain more than 80% of the variance in gene expression. Males had higher expression of mitochondrial genes and mitochondrially targeted proteins (MTPs) involved in oxidative phosphorylation (OXPHOS), while females had elevated expression of non-OXPHOS MTPs, indicating strongly sex-dimorphic energy metabolism at the whole organism level. Comparison of reciprocal F1 hybrids allowed insights into the nature of mito-nuclear interactions, showing both mitochondrial effects on nuclear expression, as well as nuclear effects on mitochondrial expression. Across both sexes, increases in mitochondrial expression with age were associated with longer life. Network analyses identified nuclear components of strong mito-nuclear interactions, and found them to be sexually dimorphic. These results highlight the profound impact of mitochondria and mito-nuclear interactions on sex- and age-specific gene expression.
Collapse
Affiliation(s)
- Ning Li
- Department of Biological Sciences, University of Southern California, 3616 Trousdale Parkway, Los Angeles, CA 90089, USA
| | | | - Suzanne Edmands
- Department of Biological Sciences, University of Southern California, 3616 Trousdale Parkway, Los Angeles, CA 90089, USA
| |
Collapse
|
6
|
Wolters JF, LaBella AL, Opulente DA, Rokas A, Hittinger CT. Mitochondrial genome diversity across the subphylum Saccharomycotina. Front Microbiol 2023; 14:1268944. [PMID: 38075892 PMCID: PMC10701893 DOI: 10.3389/fmicb.2023.1268944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 10/31/2023] [Indexed: 12/20/2023] Open
Abstract
Introduction Eukaryotic life depends on the functional elements encoded by both the nuclear genome and organellar genomes, such as those contained within the mitochondria. The content, size, and structure of the mitochondrial genome varies across organisms with potentially large implications for phenotypic variance and resulting evolutionary trajectories. Among yeasts in the subphylum Saccharomycotina, extensive differences have been observed in various species relative to the model yeast Saccharomyces cerevisiae, but mitochondrial genome sampling across many groups has been scarce, even as hundreds of nuclear genomes have become available. Methods By extracting mitochondrial assemblies from existing short-read genome sequence datasets, we have greatly expanded both the number of available genomes and the coverage across sparsely sampled clades. Results Comparison of 353 yeast mitochondrial genomes revealed that, while size and GC content were fairly consistent across species, those in the genera Metschnikowia and Saccharomyces trended larger, while several species in the order Saccharomycetales, which includes S. cerevisiae, exhibited lower GC content. Extreme examples for both size and GC content were scattered throughout the subphylum. All mitochondrial genomes shared a core set of protein-coding genes for Complexes III, IV, and V, but they varied in the presence or absence of mitochondrially-encoded canonical Complex I genes. We traced the loss of Complex I genes to a major event in the ancestor of the orders Saccharomycetales and Saccharomycodales, but we also observed several independent losses in the orders Phaffomycetales, Pichiales, and Dipodascales. In contrast to prior hypotheses based on smaller-scale datasets, comparison of evolutionary rates in protein-coding genes showed no bias towards elevated rates among aerobically fermenting (Crabtree/Warburg-positive) yeasts. Mitochondrial introns were widely distributed, but they were highly enriched in some groups. The majority of mitochondrial introns were poorly conserved within groups, but several were shared within groups, between groups, and even across taxonomic orders, which is consistent with horizontal gene transfer, likely involving homing endonucleases acting as selfish elements. Discussion As the number of available fungal nuclear genomes continues to expand, the methods described here to retrieve mitochondrial genome sequences from these datasets will prove invaluable to ensuring that studies of fungal mitochondrial genomes keep pace with their nuclear counterparts.
Collapse
Affiliation(s)
- John F. Wolters
- Laboratory of Genetics, DOE Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, Center for Genomic Science Innovation, J. F. Crow Institute for the Study of Evolution, University of Wisconsin-Madison, Madison, WI, United States
| | - Abigail L. LaBella
- Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, Charlotte, NC, United States
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, United States
| | - Dana A. Opulente
- Laboratory of Genetics, DOE Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, Center for Genomic Science Innovation, J. F. Crow Institute for the Study of Evolution, University of Wisconsin-Madison, Madison, WI, United States
- Biology Department, Villanova University, Villanova, PA, United States
| | - Antonis Rokas
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, United States
| | - Chris Todd Hittinger
- Laboratory of Genetics, DOE Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, Center for Genomic Science Innovation, J. F. Crow Institute for the Study of Evolution, University of Wisconsin-Madison, Madison, WI, United States
| |
Collapse
|
7
|
Nagarajan‐Radha V, Cordina N, Beekman M. Diet and mitonuclear haplotype interactions affect growth rate in a slime mould. Ecol Evol 2023; 13:e10508. [PMID: 37674651 PMCID: PMC10477482 DOI: 10.1002/ece3.10508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 08/12/2023] [Accepted: 08/24/2023] [Indexed: 09/08/2023] Open
Abstract
Trait expression in metazoans is strongly influenced by the balance of macronutrients (i.e. protein, carbohydrate and fat) in the diet. At the same time, an individual's genetic background seems to regulate the magnitude of phenotypic response to a particular diet. It needs to be better understood whether interactions between diet, genetic background and trait expression are found in unicellular eukaryotes. A protist-the slime mould, Physarum polycephalum can choose diets based on protein-to-carbohydrate (P:C) content to support optimal growth rate. Yet, the role of genetic background (variation in the mitochondrial and nuclear DNAs) in mediating growth rate response to dietary P:C ratios in the slime mould is unknown. Here, we studied the effects of interactions between mitochondrial and nuclear DNA haplotypes and diet (i.e. G × G × E interactions) on the growth rate of P. polycephalum. A genetic panel of six distinct strains of P. polycephalum that differ in their mitochondrial and nuclear DNA haplotypes was used to measure growth rate across five diets that varied in their P:C ratio and total calories. We first determined the strains' growth rate (total biomass and surface area) when grown on a set menu with access to a particular diet. We then assessed whether the growth rate of strains increased on a buffet menu with access to all diets. Our findings show that the growth rate of P. polycephalum is generally higher on diets containing more carbohydrates than protein and that total calories negatively affect the growth rate. Three-way interactions between mitochondrial, nuclear haplotypes and dietary P:C ratios affected the strains' surface area of growth but not biomass. Intriguingly, strains did not increase their surface area and biomass when they had access to all diets on the buffet menu. Our findings have broad implications for our understanding of the effect of mitonuclear interactions on trait expression across diverse eukaryotic lineages.
Collapse
Affiliation(s)
- Venkatesh Nagarajan‐Radha
- Behaviour, Ecology and Evolution Lab, School of Life and Environmental SciencesThe University of SydneyCamperdownNew South WalesAustralia
| | - Natalie Cordina
- Behaviour, Ecology and Evolution Lab, School of Life and Environmental SciencesThe University of SydneyCamperdownNew South WalesAustralia
| | - Madeleine Beekman
- Behaviour, Ecology and Evolution Lab, School of Life and Environmental SciencesThe University of SydneyCamperdownNew South WalesAustralia
| |
Collapse
|
8
|
Dobson AJ, Voigt S, Kumpitsch L, Langer L, Voigt E, Ibrahim R, Dowling DK, Reinhardt K. Mitonuclear interactions shape both direct and parental effects of diet on fitness and involve a SNP in mitoribosomal 16s rRNA. PLoS Biol 2023; 21:e3002218. [PMID: 37603597 PMCID: PMC10441796 DOI: 10.1371/journal.pbio.3002218] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 06/28/2023] [Indexed: 08/23/2023] Open
Abstract
Nutrition is a primary determinant of health, but responses to nutrition vary with genotype. Epistasis between mitochondrial and nuclear genomes may cause some of this variation, but which mitochondrial loci and nutrients participate in complex gene-by-gene-by-diet interactions? Furthermore, it remains unknown whether mitonuclear epistasis is involved only in the immediate responses to changes in diet, or whether mitonuclear genotype might modulate sensitivity to variation in parental nutrition, to shape intergenerational fitness responses. Here, in Drosophila melanogaster, we show that mitonuclear epistasis shapes fitness responses to variation in dietary lipids and amino acids. We also show that mitonuclear genotype modulates the parental effect of dietary lipid and amino acid variation on offspring fitness. Effect sizes for the interactions between diet, mitogenotype, and nucleogenotype were equal to or greater than the main effect of diet for some traits, suggesting that dietary impacts cannot be understood without first accounting for these interactions. Associating phenotype to mtDNA variation in a subset of populations implicated a C/T polymorphism in mt:lrRNA, which encodes the 16S rRNA of the mitochondrial ribosome. This association suggests that directionally different responses to dietary changes can result from variants on mtDNA that do not change protein coding sequence, dependent on epistatic interactions with variation in the nuclear genome.
Collapse
Affiliation(s)
- Adam J. Dobson
- School of Molecular Biosciences, University of Glasgow, Glasgow, United Kingdom
- Applied Zoology, Faculty of Biology, Technische Universität Dresden, Dresden, Germany
| | - Susanne Voigt
- Applied Zoology, Faculty of Biology, Technische Universität Dresden, Dresden, Germany
| | - Luisa Kumpitsch
- Applied Zoology, Faculty of Biology, Technische Universität Dresden, Dresden, Germany
| | - Lucas Langer
- Applied Zoology, Faculty of Biology, Technische Universität Dresden, Dresden, Germany
| | - Emmely Voigt
- Applied Zoology, Faculty of Biology, Technische Universität Dresden, Dresden, Germany
| | - Rita Ibrahim
- School of Molecular Biosciences, University of Glasgow, Glasgow, United Kingdom
| | - Damian K. Dowling
- School of Biological Sciences, Monash University, Melbourne, Australia
| | - Klaus Reinhardt
- Applied Zoology, Faculty of Biology, Technische Universität Dresden, Dresden, Germany
| |
Collapse
|
9
|
Wolters JF, LaBella AL, Opulente DA, Rokas A, Hittinger CT. Mitochondrial Genome Diversity across the Subphylum Saccharomycotina. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.28.551029. [PMID: 37577532 PMCID: PMC10418067 DOI: 10.1101/2023.07.28.551029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Eukaryotic life depends on the functional elements encoded by both the nuclear genome and organellar genomes, such as those contained within the mitochondria. The content, size, and structure of the mitochondrial genome varies across organisms with potentially large implications for phenotypic variance and resulting evolutionary trajectories. Among yeasts in the subphylum Saccharomycotina, extensive differences have been observed in various species relative to the model yeast Saccharomyces cerevisiae, but mitochondrial genome sampling across many groups has been scarce, even as hundreds of nuclear genomes have become available. By extracting mitochondrial assemblies from existing short-read genome sequence datasets, we have greatly expanded both the number of available genomes and the coverage across sparsely sampled clades. Comparison of 353 yeast mitochondrial genomes revealed that, while size and GC content were fairly consistent across species, those in the genera Metschnikowia and Saccharomyces trended larger, while several species in the order Saccharomycetales, which includes S. cerevisiae, exhibited lower GC content. Extreme examples for both size and GC content were scattered throughout the subphylum. All mitochondrial genomes shared a core set of protein-coding genes for Complexes III, IV, and V, but they varied in the presence or absence of mitochondrially-encoded canonical Complex I genes. We traced the loss of Complex I genes to a major event in the ancestor of the orders Saccharomycetales and Saccharomycodales, but we also observed several independent losses in the orders Phaffomycetales, Pichiales, and Dipodascales. In contrast to prior hypotheses based on smaller-scale datasets, comparison of evolutionary rates in protein-coding genes showed no bias towards elevated rates among aerobically fermenting (Crabtree/Warburg-positive) yeasts. Mitochondrial introns were widely distributed, but they were highly enriched in some groups. The majority of mitochondrial introns were poorly conserved within groups, but several were shared within groups, between groups, and even across taxonomic orders, which is consistent with horizontal gene transfer, likely involving homing endonucleases acting as selfish elements. As the number of available fungal nuclear genomes continues to expand, the methods described here to retrieve mitochondrial genome sequences from these datasets will prove invaluable to ensuring that studies of fungal mitochondrial genomes keep pace with their nuclear counterparts.
Collapse
Affiliation(s)
- John F. Wolters
- Laboratory of Genetics, DOE Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, Center for Genomic Science Innovation, J. F. Crow Institute for the Study of Evolution, University of Wisconsin-Madison, Madison, WI, 53726, USA
| | - Abigail L. LaBella
- Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, Charlotte NC, 28223, USA
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA; Evolutionary Studies Initiative, Vanderbilt University, Nashville, TN 37235, USA
| | - Dana A. Opulente
- Laboratory of Genetics, DOE Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, Center for Genomic Science Innovation, J. F. Crow Institute for the Study of Evolution, University of Wisconsin-Madison, Madison, WI, 53726, USA
- Biology Department Villanova University, Villanova, PA 19085, USA
| | - Antonis Rokas
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA; Evolutionary Studies Initiative, Vanderbilt University, Nashville, TN 37235, USA
| | - Chris Todd Hittinger
- Laboratory of Genetics, DOE Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, Center for Genomic Science Innovation, J. F. Crow Institute for the Study of Evolution, University of Wisconsin-Madison, Madison, WI, 53726, USA
| |
Collapse
|
10
|
Dowling DK, Wolff JN. Evolutionary genetics of the mitochondrial genome: insights from Drosophila. Genetics 2023; 224:iyad036. [PMID: 37171259 PMCID: PMC10324950 DOI: 10.1093/genetics/iyad036] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 02/05/2023] [Indexed: 05/13/2023] Open
Abstract
Mitochondria are key to energy conversion in virtually all eukaryotes. Intriguingly, despite billions of years of evolution inside the eukaryote, mitochondria have retained their own small set of genes involved in the regulation of oxidative phosphorylation (OXPHOS) and protein translation. Although there was a long-standing assumption that the genetic variation found within the mitochondria would be selectively neutral, research over the past 3 decades has challenged this assumption. This research has provided novel insight into the genetic and evolutionary forces that shape mitochondrial evolution and broader implications for evolutionary ecological processes. Many of the seminal studies in this field, from the inception of the research field to current studies, have been conducted using Drosophila flies, thus establishing the species as a model system for studies in mitochondrial evolutionary biology. In this review, we comprehensively review these studies, from those focusing on genetic processes shaping evolution within the mitochondrial genome, to those examining the evolutionary implications of interactions between genes spanning mitochondrial and nuclear genomes, and to those investigating the dynamics of mitochondrial heteroplasmy. We synthesize the contribution of these studies to shaping our understanding of the evolutionary and ecological implications of mitochondrial genetic variation.
Collapse
Affiliation(s)
- Damian K Dowling
- School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia
| | - Jonci N Wolff
- School of Biological Sciences, Monash University, Melbourne, Victoria 3800, Australia
| |
Collapse
|
11
|
Watson ET, Flanagan BA, Pascar JA, Edmands S. Mitochondrial effects on fertility and longevity in Tigriopus californicus contradict predictions of the mother's curse hypothesis. Proc Biol Sci 2022; 289:20221211. [PMID: 36382523 PMCID: PMC9667352 DOI: 10.1098/rspb.2022.1211] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 10/20/2022] [Indexed: 11/17/2022] Open
Abstract
Strict maternal inheritance of mitochondria favours the evolutionary accumulation of sex-biased fitness effects, as mitochondrial evolution occurs exclusively in female lineages. The 'mother's curse' hypothesis proposes that male-harming mutations should accumulate in mitochondrial genomes when they have neutral or beneficial effects on female fitness. Rigorous empirical tests have largely focused on Drosophila, where support for the predictions of mother's curse has been mixed. We investigated the impact of mother's curse mutations in Tigriopus californicus, a minute crustacean. Using non-recombinant backcrosses, we introgressed four divergent mitochondrial haplotypes into two nuclear backgrounds and recorded measures of fertility and longevity. We found that the phenotypic effects of mitochondrial mutations were context dependent, being influenced by the nuclear background in which they were expressed, as well as the sex of the individual and rearing temperature. Mitochondrial haplotype effects were greater for fertility than longevity, and temperature effects were greater for longevity. However, in opposition to mother's curse expectations, females had higher mitochondrial genetic variance than males for fertility and longevity, little evidence of sexual antagonism favouring females was found, and the impacts of mitonuclear mismatch harmed females but not males. Together, this indicates that selection on mitochondrial variation has not resulted in the accumulation of male mutation load in Tigriopus californicus.
Collapse
Affiliation(s)
- Eric T. Watson
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-0001, USA
| | - Ben A. Flanagan
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-0001, USA
| | - Jane A. Pascar
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-0001, USA
| | - Suzanne Edmands
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089-0001, USA
| |
Collapse
|
12
|
Weaver RJ, Rabinowitz S, Thueson K, Havird JC. Genomic Signatures of Mitonuclear Coevolution in Mammals. Mol Biol Evol 2022; 39:6775223. [PMID: 36288802 PMCID: PMC9641969 DOI: 10.1093/molbev/msac233] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mitochondrial (mt) and nuclear-encoded proteins are integrated in aerobic respiration, requiring co-functionality among gene products from fundamentally different genomes. Different evolutionary rates, inheritance mechanisms, and selection pressures set the stage for incompatibilities between interacting products of the two genomes. The mitonuclear coevolution hypothesis posits that incompatibilities may be avoided if evolution in one genome selects for complementary changes in interacting genes encoded by the other genome. Nuclear compensation, in which deleterious mtDNA changes are offset by compensatory nuclear changes, is often invoked as the primary mechanism for mitonuclear coevolution. Yet, direct evidence supporting nuclear compensation is rare. Here, we used data from 58 mammalian species representing eight orders to show strong correlations between evolutionary rates of mt and nuclear-encoded mt-targeted (N-mt) proteins, but not between mt and non-mt-targeted nuclear proteins, providing strong support for mitonuclear coevolution across mammals. N-mt genes with direct mt interactions also showed the strongest correlations. Although most N-mt genes had elevated dN/dS ratios compared to mt genes (as predicted under nuclear compensation), N-mt sites in close contact with mt proteins were not overrepresented for signs of positive selection compared to noncontact N-mt sites (contrary to predictions of nuclear compensation). Furthermore, temporal patterns of N-mt and mt amino acid substitutions did not support predictions of nuclear compensation, even in positively selected, functionally important residues with direct mitonuclear contacts. Overall, our results strongly support mitonuclear coevolution across ∼170 million years of mammalian evolution but fail to support nuclear compensation as the major mode of mitonuclear coevolution.
Collapse
Affiliation(s)
- Ryan J Weaver
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA.,Department of Natural Resource Ecology and Management, Iowa State University, Ames, IA
| | | | - Kiley Thueson
- Department of Integrative Biology, University of Texas, Austin, TX
| | - Justin C Havird
- Department of Integrative Biology, University of Texas, Austin, TX
| |
Collapse
|
13
|
Koch RE, Dowling DK. Effects of mitochondrial haplotype on pre-copulatory mating success in male fruit flies (Drosophila melanogaster). J Evol Biol 2022; 35:1396-1402. [PMID: 35988150 DOI: 10.1111/jeb.14080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 07/11/2022] [Accepted: 07/19/2022] [Indexed: 01/07/2023]
Abstract
While mitochondria have long been understood to be critical to cellular function, questions remain as to how genetic variation within mitochondria may underlie variation in general metrics of organismal function. To date, studies investigating links between mitochondrial genotype and phenotype have largely focused on differences in expression of genes and physiological and life-history traits across haplotypes. Mating display behaviours may also be sensitive to mitochondrial functionality and so may also be affected by sequence variation in mitochondrial DNA, with consequences for sexual selection and fitness. Here, we tested whether the pre-copulatory mating success of male fruit flies (Drosophila melanogaster) varies across six different mitochondrial haplotypes expressed alongside a common nuclear genetic background. We found a significant effect of mitochondrial haplotype on our measure of competitive mating success, driven largely by the relatively poor performance of males with one particular haplotype. This haplotype, termed 'Brownsville', has previously been shown to have complex and sex-specific effects, most notably including depressed fertility in males but not females. Our study extends this disproportionate effect on male reproductive success to pre-copulatory aspects of reproduction. Our results demonstrate that mutations in mitochondrial DNA can plausibly affect pre-copulatory mating success, with implications for future study into the subcellular underpinnings of such behaviours and the information they may communicate.
Collapse
Affiliation(s)
- Rebecca E Koch
- School of Biological Sciences, Monash University, Melbourne, Victoria, Australia.,Department of Biological Science, The University of Tulsa, Tulsa, Oklahoma, USA
| | - Damian K Dowling
- School of Biological Sciences, Monash University, Melbourne, Victoria, Australia
| |
Collapse
|
14
|
Jacobs HT, Ballard JWO. What physiological role(s) does the alternative oxidase perform in animals? BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2022; 1863:148556. [PMID: 35367450 DOI: 10.1016/j.bbabio.2022.148556] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 03/25/2022] [Accepted: 03/25/2022] [Indexed: 06/14/2023]
Abstract
Although the alternative oxidase, AOX, was known to be widespread in the animal kingdom by 2004, its exact physiological role in animals remains poorly understood. Here we present what evidence has accumulated thus far, indicating that it may play a role in enabling animals to resist various kinds of stress, including toxins, abnormal oxygen or nutrient levels, protein unfolding, dessication and pathogen attack. Much of our knowledge comes from studies in model organisms, where any benefits from exogenously expressed AOX may be masked by its unregulated expression, which may itself be stressful. The further question arises as to why AOX has been lost from some major crown groups, namely vertebrates, insects and cephalopods, if it plays important roles favouring the survival of other animals. We conclude by presenting some speculative ideas addressing this question, and an outline of how it might be approached experimentally.
Collapse
Affiliation(s)
- Howard T Jacobs
- Faculty of Medicine and Health Technology, FI-33014 Tampere University, Finland; Department of Environment and Genetics, La Trobe University, Melbourne, Victoria 3086, Australia.
| | - J William O Ballard
- Department of Environment and Genetics, La Trobe University, Melbourne, Victoria 3086, Australia; School of BioSciences, University of Melbourne, Parkville, Victoria 3010, Australia
| |
Collapse
|
15
|
Parakatselaki ME, Zhu CT, Rand D, Ladoukakis ED. NUMTs Can Imitate Biparental Transmission of mtDNA-A Case in Drosophila melanogaster. Genes (Basel) 2022; 13:genes13061023. [PMID: 35741785 PMCID: PMC9222939 DOI: 10.3390/genes13061023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 05/27/2022] [Accepted: 06/02/2022] [Indexed: 11/16/2022] Open
Abstract
mtDNA sequences can be incorporated into the nuclear genome and produce nuclear mitochondrial fragments (NUMTs), which resemble mtDNA in their sequence but are transmitted biparentally, like the nuclear genome. NUMTs can be mistaken as real mtDNA and may lead to the erroneous impression that mtDNA is biparentally transmitted. Here, we report a case of mtDNA heteroplasmy in a Drosophila melanogaster DGRP line, in which the one haplotype was biparentally transmitted in an autosomal manner. Given the sequence identity of this haplotype with the mtDNA, the crossing experiments led to uncertainty about whether heteroplasmy was real or an artifact due to a NUMT. More specific experiments revealed that there is a large NUMT insertion in the X chromosome of a specific DGRP line, imitating biparental inheritance of mtDNA. Our result suggests that studies on mtDNA heteroplasmy and on mtDNA inheritance should first exclude the possibility of NUMT interference in their data.
Collapse
Affiliation(s)
| | - Chen-Tseh Zhu
- Department of Ecology, Evolutionary and Organismal Biology, Brown University, Providence, RI 02912, USA; (C.-T.Z.); (D.R.)
| | - David Rand
- Department of Ecology, Evolutionary and Organismal Biology, Brown University, Providence, RI 02912, USA; (C.-T.Z.); (D.R.)
| | - Emmanuel D. Ladoukakis
- Department of Biology, University of Crete, Voutes University Campus, 70013 Iraklio, Greece;
- Correspondence: ; Tel.: +30-281-039-4067
| |
Collapse
|
16
|
Rand DM, Mossman JA, Spierer AN, Santiago JA. Mitochondria as environments for the nuclear genome in Drosophila: mitonuclear G×G×E. J Hered 2022; 113:37-47. [PMID: 34964900 PMCID: PMC8851671 DOI: 10.1093/jhered/esab066] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Accepted: 10/21/2021] [Indexed: 12/13/2022] Open
Abstract
Mitochondria evolved from a union of microbial cells belonging to distinct lineages that were likely anaerobic. The evolution of eukaryotes required a massive reorganization of the 2 genomes and eventual adaptation to aerobic environments. The nutrients and oxygen that sustain eukaryotic metabolism today are processed in mitochondria through coordinated expression of 37 mitochondrial genes and over 1000 nuclear genes. This puts mitochondria at the nexus of gene-by-gene (G×G) and gene-by-environment (G×E) interactions that sustain life. Here we use a Drosophila model of mitonuclear genetic interactions to explore the notion that mitochondria are environments for the nuclear genome, and vice versa. We construct factorial combinations of mtDNA and nuclear chromosomes to test for epistatic interactions (G×G), and expose these mitonuclear genotypes to altered dietary environments to examine G×E interactions. We use development time and genome-wide RNAseq analyses to assess the relative contributions of mtDNA, nuclear chromosomes, and environmental effects on these traits (mitonuclear G×G×E). We show that the nuclear transcriptional response to alternative mitochondrial "environments" (G×G) has significant overlap with the transcriptional response of mitonuclear genotypes to altered dietary environments. These analyses point to specific transcription factors (e.g., giant) that mediated these interactions, and identified coexpressed modules of genes that may account for the overlap in differentially expressed genes. Roughly 20% of the transcriptome includes G×G genes that are concordant with G×E genes, suggesting that mitonuclear interactions are part of an organism's environment.
Collapse
Affiliation(s)
- David M Rand
- Department of Ecology, Evolution and Organismal Biology, Brown University, 80 Waterman Street, Providence, Rhode Island 02912, USA
| | - James A Mossman
- Department of Ecology, Evolution and Organismal Biology, Brown University, 80 Waterman Street, Providence, Rhode Island 02912, USA
| | - Adam N Spierer
- Department of Ecology, Evolution and Organismal Biology, Brown University, 80 Waterman Street, Providence, Rhode Island 02912, USA
| | - John A Santiago
- Department of Molecular Biology, Cellular Biology, and Biochemistry, Brown University, 80 Waterman Street, Providence, Rhode Island 02912, USA
- Department of Pathology and Laboratory Medicine, Brown University, 80 Waterman Street, Providence, Rhode Island 02912, USA
| |
Collapse
|
17
|
Flanagan BA, Li N, Edmands S. Mitonuclear interactions alter sex-specific longevity in a species without sex chromosomes. Proc Biol Sci 2021; 288:20211813. [PMID: 34727715 PMCID: PMC8564613 DOI: 10.1098/rspb.2021.1813] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 10/11/2021] [Indexed: 12/28/2022] Open
Abstract
Impaired mitochondrial function can lead to senescence and the ageing phenotype. Theory predicts degenerative ageing phenotypes and mitochondrial pathologies may occur more frequently in males due to the matrilineal inheritance pattern of mitochondrial DNA observed in most eukaryotes. Here, we estimated the sex-specific longevity for parental and reciprocal F1 hybrid crosses for inbred lines derived from two allopatric Tigriopus californicus populations with over 20% mitochondrial DNA divergence. T. californicus lacks sex chromosomes allowing for more direct testing of mitochondrial function in sex-specific ageing. To better understand the ageing mechanism, we estimated two age-related phenotypes (mtDNA content and 8-hydroxy-20-deoxyguanosine (8-OH-dG) DNA damage) at two time points in the lifespan. Sex differences in lifespan depended on the mitochondrial and nuclear backgrounds, including differences between reciprocal F1 crosses which have different mitochondrial haplotypes on a 50 : 50 nuclear background, with nuclear contributions coming from alternative parents. Young females showed the highest mtDNA content which decreased with age, while DNA damage in males increased with age and exceed that of females 56 days after hatching. The adult sex ratio was male-biased and was attributed to complex mitonuclear interactions. Results thus demonstrate that sex differences in ageing depend on mitonuclear interactions in the absence of sex chromosomes.
Collapse
Affiliation(s)
- Ben A. Flanagan
- Department of Biological Sciences, University of Southern California, 3616 Trousdale Parkway, AHF 130, Los Angeles, CA 90089, USA
| | - Ning Li
- Department of Biological Sciences, University of Southern California, 3616 Trousdale Parkway, AHF 130, Los Angeles, CA 90089, USA
| | - Suzanne Edmands
- Department of Biological Sciences, University of Southern California, 3616 Trousdale Parkway, AHF 130, Los Angeles, CA 90089, USA
| |
Collapse
|
18
|
Mitonuclear mismatch alters nuclear gene expression in naturally introgressed Rhinolophus bats. Front Zool 2021; 18:42. [PMID: 34488775 PMCID: PMC8419968 DOI: 10.1186/s12983-021-00424-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 07/20/2021] [Indexed: 01/23/2023] Open
Abstract
Background Mitochondrial function involves the interplay between mitochondrial and nuclear genomes. Such mitonuclear interactions can be disrupted by the introgression of mitochondrial DNA between taxa or divergent populations. Previous studies of several model systems (e.g. Drosophila) indicate that the disruption of mitonuclear interactions, termed mitonuclear mismatch, can alter nuclear gene expression, yet few studies have focused on natural populations. Results Here we study a naturally introgressed population in the secondary contact zone of two subspecies of the intermediate horseshoe bat (Rhinolophus affinis), in which individuals possess either mitonuclear matched or mismatched genotypes. We generated transcriptome data for six tissue types from five mitonuclear matched and five mismatched individuals. Our results revealed strong tissue-specific effects of mitonuclear mismatch on nuclear gene expression with the largest effect seen in pectoral muscle. Moreover, consistent with the hypothesis that genes associated with the response to oxidative stress may be upregulated in mitonuclear mismatched individuals, we identified several such gene candidates, including DNASE1L3, GPx3 and HSPB6 in muscle, and ISG15 and IFI6 in heart. Conclusion Our study reveals how mitonuclear mismatch arising from introgression in natural populations is likely to have fitness consequences. Underlying the processes that maintain mitonuclear discordance is a step forward to understand the role of mitonuclear interactions in population divergence and speciation. Supplementary Information The online version contains supplementary material available at 10.1186/s12983-021-00424-x.
Collapse
|
19
|
Iverson ENK, Nix R, Abebe A, Havird JC. Thermal Responses Differ across Levels of Biological Organization. Integr Comp Biol 2021; 60:361-374. [PMID: 32483618 DOI: 10.1093/icb/icaa052] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Temperature is one of the most important environmental factors driving the genome-to-phenome relationship. Metabolic rates and related biological processes are predicted to increase with temperature due to the biophysical laws of chemical reactions. However, selection can also act on these processes across scales of biological organization, from individual enzymes to whole organisms. Although some studies have examined thermal responses across multiple scales, there is no general consensus on how these responses vary depending on the level of organization, or whether rates actually follow predicted theoretical patterns such as Arrhenius-like exponential responses or thermal performance curves (TPCs) that show peak responses. Here, we performed a meta-analysis on studies of ectotherms where biological rates were measured across the same set of temperatures, but at multiple levels of biological organization: enzyme activities, mitochondrial respiration, and/or whole-animal metabolic rates. Our final dataset consisted of 235 pairwise comparisons between levels of organization from 13 publications. Thermal responses differed drastically across levels of biological organization, sometimes showing completely opposite patterns. We developed a new effect size metric, "organizational disagreement" (OD) to quantify the difference in responses among levels of biological organization. Overall, rates at higher levels of biological organization (e.g., whole animal metabolic rates) increased more quickly with temperature than rates at lower levels, contrary to our predictions. Responses may differ across levels due to differing consequences of biochemical laws with increasing organization or due to selection for different responses. However, taxa and tissues examined generally did not affect OD. Theoretical TPCs, where rates increase to a peak value and then drop, were only rarely observed (12%), possibly because a broad range of test temperatures was rarely investigated. Exponential increases following Arrhenius predictions were more common (29%). This result suggests a classic assumption about thermal responses in biological rates is rarely observed in empirical datasets, although our results should be interpreted cautiously due to the lack of complete thermal profiles. We advocate for authors to explicitly address OD in their interpretations and to measure thermal responses across a wider, more incremental range of temperatures. These results further emphasize the complexity of connecting the genome to the phenome when environmental plasticity is incorporated: the impact of the environment on the phenotype can depend on the scale of organization considered.
Collapse
Affiliation(s)
- Erik N K Iverson
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Rachel Nix
- Hankamer School of Business, Baylor University, Waco, TX 76798, USA
| | - Ash Abebe
- Department of Mathematics & Statistics, Auburn University, Auburn, AL 36849, USA
| | - Justin C Havird
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712, USA
| |
Collapse
|
20
|
Breton S, Ghiselli F, Milani L. Mitochondrial Short-Term Plastic Responses and Long-Term Evolutionary Dynamics in Animal Species. Genome Biol Evol 2021; 13:6248094. [PMID: 33892508 PMCID: PMC8290114 DOI: 10.1093/gbe/evab084] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 04/13/2021] [Accepted: 04/20/2021] [Indexed: 12/15/2022] Open
Abstract
How do species respond or adapt to environmental changes? The answer to this depends partly on mitochondrial epigenetics and genetics, new players in promoting adaptation to both short- and long-term environmental changes. In this review, we explore how mitochondrial epigenetics and genetics mechanisms, such as mtDNA methylation, mtDNA-derived noncoding RNAs, micropeptides, mtDNA mutations, and adaptations, can contribute to animal plasticity and adaptation. We also briefly discuss the challenges in assessing mtDNA adaptive evolution. In sum, this review covers new advances in the field of mitochondrial genomics, many of which are still controversial, and discusses processes still somewhat obscure, and some of which are still quite speculative and require further robust experimentation.
Collapse
Affiliation(s)
- Sophie Breton
- Department of Biological Sciences, University of Montreal, Quebec, Canada
| | - Fabrizio Ghiselli
- Department of Biological, Geological, and Environmental Sciences, University of Bologna, Italy
| | - Liliana Milani
- Department of Biological, Geological, and Environmental Sciences, University of Bologna, Italy
| |
Collapse
|
21
|
Gonzalez S. The Role of Mitonuclear Incompatibility in Bipolar Disorder Susceptibility and Resilience Against Environmental Stressors. Front Genet 2021; 12:636294. [PMID: 33815470 PMCID: PMC8010675 DOI: 10.3389/fgene.2021.636294] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 02/22/2021] [Indexed: 12/23/2022] Open
Abstract
It has been postulated that mitochondrial dysfunction has a significant role in the underlying pathophysiology of bipolar disorder (BD). Mitochondrial functioning plays an important role in regulating synaptic transmission, brain function, and cognition. Neuronal activity is energy dependent and neurons are particularly sensitive to changes in bioenergetic fluctuations, suggesting that mitochondria regulate fundamental aspects of brain function. Vigorous evidence supports the role of mitochondrial dysfunction in the etiology of BD, including dysregulated oxidative phosphorylation, general decrease of energy, altered brain bioenergetics, co-morbidity with mitochondrial disorders, and association with genetic variants in mitochondrial DNA (mtDNA) or nuclear-encoded mitochondrial genes. Despite these advances, the underlying etiology of mitochondrial dysfunction in BD is unclear. A plausible evolutionary explanation is that mitochondrial-nuclear (mitonuclear) incompatibility leads to a desynchronization of machinery required for efficient electron transport and cellular energy production. Approximately 1,200 genes, encoded from both nuclear and mitochondrial genomes, are essential for mitochondrial function. Studies suggest that mitochondrial and nuclear genomes co-evolve, and the coordinated expression of these interacting gene products are essential for optimal organism function. Incompatibilities between mtDNA and nuclear-encoded mitochondrial genes results in inefficiency in electron flow down the respiratory chain, differential oxidative phosphorylation efficiency, increased release of free radicals, altered intracellular Ca2+ signaling, and reduction of catalytic sites and ATP production. This review explores the role of mitonuclear incompatibility in BD susceptibility and resilience against environmental stressors.
Collapse
Affiliation(s)
- Suzanne Gonzalez
- Department of Psychiatry and Behavioral Health, Department of Pharmacology, Penn State College of Medicine, Hershey, PA, United States
| |
Collapse
|
22
|
Insights into the Mitochondrial and Nuclear Genome Diversity of Two High Yielding Strains of Laying Hens. Animals (Basel) 2021; 11:ani11030825. [PMID: 33804055 PMCID: PMC8001891 DOI: 10.3390/ani11030825] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 03/05/2021] [Accepted: 03/10/2021] [Indexed: 12/06/2022] Open
Abstract
Simple Summary Mitochondria are commonly known as “the powerhouse of the cell”, influencing the fitness, lifespan and metabolism of eukaryotic organisms. In our study we examined mitochondrial and nuclear genomic diversity in two high yielding strains of laying hens. We tested if the mitochondrial genome affects functional traits such as body weight and phosphorus utilization. We discovered a surprisingly low mitochondrial genetic diversity and an unequal distribution of the haplotypes among both strains, leading to limitations of robust links to phenotypic traits. In contrast, we found similar levels of nuclear genome diversity in both strains. Our study explores the potential influence of the mitochondrial genome on phenotypic traits and thus contributes to a better understanding of the function of this organelle in laying hens. Further, we focus on its usefulness as a genetic marker, which is often underestimated in breeding approaches, given the different inheritance mechanism compared to the nuclear genome. Abstract Mitochondria are essential components of eukaryotes as they are involved in several organismic key processes such as energy production, apoptosis and cell growth. Despite their importance for the metabolism and physiology of all eukaryotic organisms, the impact of mitochondrial haplotype variation has only been studied for very few species. In this study we sequenced the mitochondrial genome of 180 individuals from two different strains of laying hens. The resulting haplotypes were combined with performance data such as body weight, feed intake and phosphorus utilization to assess their influence on the hens in five different life stages. After detecting a surprisingly low level of genetic diversity, we investigated the nuclear genetic background to estimate whether the low mitochondrial diversity is representative for the whole genetic background of the strains. Our results highlight the need for more in-depth investigation of the genetic compositions and mito-nuclear interaction in individuals to elucidate the basis of phenotypic performance differences. In addition, we raise the question of how the lack of mitochondrial variation developed, since the mitochondrial genome represents genetic information usually not considered in breeding approaches.
Collapse
|
23
|
Carnegie L, Reuter M, Fowler K, Lane N, Camus MF. Mother's curse is pervasive across a large mitonuclear Drosophila panel. Evol Lett 2021; 5:230-239. [PMID: 34136271 PMCID: PMC8190446 DOI: 10.1002/evl3.221] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 01/18/2021] [Accepted: 02/11/2021] [Indexed: 01/16/2023] Open
Abstract
The maternal inheritance of mitochondrial genomes entails a sex‐specific selective sieve, whereby mutations in mitochondrial DNA can only respond to selection acting on females. In theory, this enables male‐harming mutations to accumulate in mitochondrial genomes as long as they are neutral, beneficial, or only slightly deleterious to females. Ultimately, this bias could drive the evolution of male‐specific mitochondrial mutation loads, an idea known as mother's curse. Earlier work on this hypothesis has mainly used small Drosophila panels, in which naturally sourced mitochondrial genomes were coupled to an isogenic nuclear background. The lack of nuclear genetic variation in these designs has precluded robust generalization. Here, we test the predictions of mother's curse using a large Drosophila mitonuclear genetic panel, comprising nine isogenic nuclear genomes coupled to nine mitochondrial haplotypes, giving a total of 81 different mitonuclear genotypes. Following a predictive framework, we tested the mother's curse hypothesis by screening our panel for wing size. This trait is tightly correlated with overall body size and is sexually dimorphic in Drosophila. Moreover, growth is heavily reliant on metabolism and mitochondrial function, making wing size an ideal trait for the study of the impact of mitochondrial variation. We detect high levels of mitonuclear epistasis, and more importantly, we report that mitochondrial genetic variance is larger in male than female Drosophila for eight out of the nine nuclear genetic backgrounds used. These results demonstrate that the maternal inheritance of mitochondrial DNA does indeed modulate male life history traits in a more generalisable way than previously demonstrated.
Collapse
Affiliation(s)
- Lorcan Carnegie
- Research Department of Genetics, Evolution and Environment University College London London WC1E 6BT United Kingdom
| | - Max Reuter
- Research Department of Genetics, Evolution and Environment University College London London WC1E 6BT United Kingdom
| | - Kevin Fowler
- Research Department of Genetics, Evolution and Environment University College London London WC1E 6BT United Kingdom
| | - Nick Lane
- Research Department of Genetics, Evolution and Environment University College London London WC1E 6BT United Kingdom
| | - M Florencia Camus
- Research Department of Genetics, Evolution and Environment University College London London WC1E 6BT United Kingdom
| |
Collapse
|
24
|
Spierer AN, Yoon D, Zhu CT, Rand DM. FreeClimber: automated quantification of climbing performance in Drosophila. J Exp Biol 2021; 224:jeb229377. [PMID: 33188065 PMCID: PMC7823161 DOI: 10.1242/jeb.229377] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 11/05/2020] [Indexed: 12/26/2022]
Abstract
Negative geotaxis (climbing) performance is a useful metric for quantifying Drosophila health. Manual methods to quantify climbing performance are tedious and often biased, while many available computational methods have challenging hardware or software requirements. We present an alternative: FreeClimber. This open source, Python-based platform subtracts a video's static background to improve detection for flies moving across heterogeneous backgrounds. FreeClimber calculates a cohort's velocity as the slope of the most linear portion of a mean vertical position versus time curve. It can run from a graphical user interface for optimization or a command line interface for high-throughput and automated batch processing, improving accessibility for users with different expertise. FreeClimber outputs calculated slopes, spot locations for follow-up analyses (e.g. tracking), and several visualizations and plots. We demonstrate FreeClimber's utility in a longitudinal study for endurance exercise performance in Drosophila mitonuclear genotypes using six distinct mitochondrial haplotypes paired with a common D. melanogaster nuclear background.
Collapse
Affiliation(s)
- Adam N Spierer
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA
| | - Denise Yoon
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Chen-Tseh Zhu
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA
- Global Plant Breeding, Bayer Crop Science, Chesterfield, MO 63017, USA
| | - David M Rand
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA
| |
Collapse
|
25
|
Abstract
Temperature is a critical abiotic factor shaping the distribution and abundance of species, but the mechanisms that underpin organismal thermal limits remain poorly understood. One possible mechanism underlying these limits is the failure of mitochondrial processes, as mitochondria play a crucial role in animals as the primary site of ATP production. Conventional measures of mitochondrial performance suggest that these organelles can function at temperatures much higher than those that limit whole-organism function, suggesting that they are unlikely to set organismal thermal limits. However, this conclusion is challenged by recent data connecting sequence variation in mitochondrial genes to whole-organism thermal tolerance. Here, we review the current state of knowledge of mitochondrial responses to thermal extremes and ask whether they are consistent with a role for mitochondrial function in shaping whole-organism thermal limits. The available data are fragmentary, but it is possible to draw some conclusions. There is little evidence that failure of maximal mitochondrial oxidative capacity as assessed in vitro sets thermal limits, but there is some evidence to suggest that temperature effects on ATP synthetic capacity may be important. Several studies suggest that loss of mitochondrial coupling is associated with the thermal limits for organismal growth, although this needs to be rigorously tested. Most studies have utilized isolated mitochondrial preparations to assess the effects of temperature on these organelles, and there remain many untapped opportunities to address these questions using preparations that retain more of their biological context to better connect these subcellular processes with whole-organism thermal limits.
Collapse
Affiliation(s)
- Dillon J Chung
- National Heart Lung and Blood Institute, National Institutes of Health, 10 Center Drive, Bethesda, MD 20814, USA
| | - Patricia M Schulte
- Department of Zoology, University of British Columbia, 6270 University Blvd, Vancouver, British Columbia, Canada V6T 1Z4
| |
Collapse
|
26
|
Jacobs HT, George J, Kemppainen E. Regulation of growth in Drosophila melanogaster: the roles of mitochondrial metabolism. J Biochem 2020; 167:267-277. [PMID: 31926002 PMCID: PMC7048069 DOI: 10.1093/jb/mvaa002] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Accepted: 01/05/2020] [Indexed: 12/14/2022] Open
Abstract
Mitochondrial functions are often considered purely from the standpoint of catabolism, but in growing cells they are mainly dedicated to anabolic processes, and can have a profound impact on the rate of growth. The Drosophila larva, which increases in body mass ∼200-fold over the course of ∼3 days at 25°C, provides an excellent model to study the underlying regulatory machinery that connects mitochondrial metabolic capacity to growth. In this review, we will focus on several key aspects of this machinery: nutrient sensing, endocrine control of feeding and nutrient mobilization, metabolic signalling, protein synthesis regulation and pathways of steroid biosynthesis and activity. In all these aspects, mitochondria appear to play a crucial role.
Collapse
Affiliation(s)
- Howard T Jacobs
- Faculty of Medicine and Health Technology, FI-33014 Tampere University, Finland
| | - Jack George
- Faculty of Medicine and Health Technology, FI-33014 Tampere University, Finland
| | - Esko Kemppainen
- Faculty of Medicine and Health Technology, FI-33014 Tampere University, Finland
| |
Collapse
|
27
|
Towarnicki SG, Ballard JWO. Towards understanding the evolutionary dynamics of mtDNA. Mitochondrial DNA A DNA Mapp Seq Anal 2020; 31:355-364. [PMID: 33026269 DOI: 10.1080/24701394.2020.1830076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Historically, mtDNA was considered a selectively neutral marker that was useful for estimating the population genetic history of the maternal lineage. Over time there has been an increasing appreciation of mtDNA and mitochondria in maintaining cellular and organismal health. Beyond energy production, mtDNA and mitochondria have critical cellular roles in signalling. Here we briefly review the structure of mtDNA and the role of the mitochondrion in energy production. We then discuss the predictions that can be obtained from quaternary structure modelling and focus on mitochondrial complex I. Complex I is the primary entry point for electrons into the electron transport system is the largest respiratory complex of the chain and produces about 40% of the proton flux used to synthesize ATP. A focus of the review is Drosophila's utility as a model organism to study the selective advantage of specific mutations. However, we note that the incorporation of insights from a multitude of systems is necessary to fully understand the range of roles that mtDNA has in organismal fitness. We speculate that dietary changes can illicit stress responses that influence the selective advantage of specific mtDNA mutations and cause spatial and temporal fluctuations in the frequencies of mutations. We conclude that developing our understanding of the roles mtDNA has in determining organismal fitness will enable increased evolutionary insight and propose we can no longer assume it is evolving as a strictly neutral marker without testing this hypothesis.
Collapse
Affiliation(s)
- Samuel G Towarnicki
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia
| | - J William O Ballard
- School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia
| |
Collapse
|
28
|
Nguyen THM, Sondhi S, Ziesel A, Paliwal S, Fiumera HL. Mitochondrial-nuclear coadaptation revealed through mtDNA replacements in Saccharomyces cerevisiae. BMC Evol Biol 2020; 20:128. [PMID: 32977769 PMCID: PMC7517635 DOI: 10.1186/s12862-020-01685-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 09/07/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mitochondrial function requires numerous genetic interactions between mitochondrial- and nuclear- encoded genes. While selection for optimal mitonuclear interactions should result in coevolution between both genomes, evidence for mitonuclear coadaptation is challenging to document. Genetic models where mitonuclear interactions can be explored are needed. RESULTS We systematically exchanged mtDNAs between 15 Saccharomyces cerevisiae isolates from a variety of ecological niches to create 225 unique mitochondrial-nuclear genotypes. Analysis of phenotypic profiles confirmed that environmentally-sensitive interactions between mitochondrial and nuclear genotype contributed to growth differences. Exchanges of mtDNAs between strains of the same or different clades were just as likely to demonstrate mitonuclear epistasis although epistatic effect sizes increased with genetic distances. Strains with their original mtDNAs were more fit than strains with synthetic mitonuclear combinations when grown in media that resembled isolation habitats. CONCLUSIONS This study shows that natural variation in mitonuclear interactions contributes to fitness landscapes. Multiple examples of coadapted mitochondrial-nuclear genotypes suggest that selection for mitonuclear interactions may play a role in helping yeasts adapt to novel environments and promote coevolution.
Collapse
Affiliation(s)
- Tuc H M Nguyen
- Department of Biological Sciences, Binghamton University, Binghamton, NY, USA
| | - Sargunvir Sondhi
- Department of Biological Sciences, Binghamton University, Binghamton, NY, USA
| | - Andrew Ziesel
- Department of Biological Sciences, Binghamton University, Binghamton, NY, USA
| | - Swati Paliwal
- Department of Bioscience and Biotechnology, Banasthali Vidyapith, Rajasthan, India
| | - Heather L Fiumera
- Department of Biological Sciences, Binghamton University, Binghamton, NY, USA.
| |
Collapse
|
29
|
Keaney TA, Wong HWS, Dowling DK, Jones TM, Holman L. Sibling rivalry versus mother's curse: can kin competition facilitate a response to selection on male mitochondria? Proc Biol Sci 2020; 287:20200575. [PMID: 32605521 DOI: 10.1098/rspb.2020.0575] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Assuming that fathers never transmit mitochondrial DNA (mtDNA) to their offspring, mitochondrial mutations that affect male fitness are invisible to direct selection on males, leading to an accumulation of male-harming alleles in the mitochondrial genome (mother's curse). However, male phenotypes encoded by mtDNA can still undergo adaptation via kin selection provided that males interact with females carrying related mtDNA, such as their sisters. Here, using experiments with Drosophila melanogaster carrying standardized nuclear DNA but distinct mitochondrial DNA, we test whether the mitochondrial haplotype carried by interacting pairs of larvae affects survival to adulthood, as well as the fitness of the adults. Although mtDNA had no detectable direct or indirect genetic effect on larva-to-adult survival, the fitness of male and female adults was significantly affected by their own mtDNA and the mtDNA carried by their social partner in the larval stage. Thus, mtDNA mutations that alter the effect of male larvae on nearby female larvae (which often carry the same mutation, due to kinship) could theoretically respond to kin selection. We discuss the implications of our findings for the evolution of mitochondria and other maternally inherited endosymbionts.
Collapse
Affiliation(s)
- Thomas A Keaney
- School of Biosciences, The University of Melbourne, Vic. 3010, Australia
| | - Heidi W S Wong
- School of Biosciences, The University of Melbourne, Vic. 3010, Australia
| | - Damian K Dowling
- School of Biological Sciences, Monash University, Clayton, Vic. 3800, Australia
| | - Therésa M Jones
- School of Biosciences, The University of Melbourne, Vic. 3010, Australia
| | - Luke Holman
- School of Biosciences, The University of Melbourne, Vic. 3010, Australia
| |
Collapse
|
30
|
Development of fly tolerance to consuming a high-protein diet requires physiological, metabolic and transcriptional changes. Biogerontology 2020; 21:619-636. [PMID: 32468146 DOI: 10.1007/s10522-020-09880-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 04/24/2020] [Indexed: 12/25/2022]
Abstract
Mortality in insects consuming high-protein-and-low-carbohydrate diets resembles a type III lifespan curve with increased mortality at an early age and few survivors that live a relatively long lifespan. We selected for a Drosophila line able to live for a long time on an imbalanced high-protein-low-carbohydrate diet by carrying out five rounds of breeding to select for the most long-lived survivors. Adaptation to this diet in the selected line was studied at the biochemical, physiological and transcriptomic levels. The selected line of flies consumed less of the imbalanced food but also accumulated more storage metabolites: glycogen, triacylglycerides, and trehalose. Selected flies also had a higher activity of alanine transaminase and a higher urea content. Adaptation of the selected line on the transcriptomic level was characterized by down-regulation of genes encoding serine endopeptidases (Jon25i, Jon25ii, betaTry, and others) but up-regulation of genes encoding proteins related to the immune system, such as antimicrobial peptides, Turandot-family humoral factors, hexamerin isoforms, and vitellogenin. These sets of down- and up-regulated genes were similar to those observed in fruit flies with suppressed juvenile hormone signaling. Our data show that the physiological adaptation of fruit flies to a high-protein-low-carbohydrate diet occurs via intuitive pathways, namely a decrease in food consumption, conversion of amino acids into ketoacids to compensate for the lack of carbohydrate, and accumulation of storage metabolites to eliminate the negative effects of excess amino acids. Nevertheless, transcriptomic adaptation occurs in a counter-intuitive way likely via an influence of gut microbiota on food digestion.
Collapse
|
31
|
Salminen TS, Vale PF. Drosophila as a Model System to Investigate the Effects of Mitochondrial Variation on Innate Immunity. Front Immunol 2020; 11:521. [PMID: 32269576 PMCID: PMC7109263 DOI: 10.3389/fimmu.2020.00521] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 03/06/2020] [Indexed: 12/14/2022] Open
Abstract
Understanding why the response to infection varies between individuals remains one of the major challenges in immunology and infection biology. A substantial proportion of this heterogeneity can be explained by individual genetic differences which result in variable immune responses, and there are many examples of polymorphisms in nuclear-encoded genes that alter immunocompetence. However, how immunity is affected by genetic polymorphism in an additional genome, inherited maternally inside mitochondria (mtDNA), has been relatively understudied. Mitochondria are increasingly recognized as important mediators of innate immune responses, not only because they are the main source of energy required for costly immune responses, but also because by-products of mitochondrial metabolism, such as reactive oxygen species (ROS), may have direct microbicidal action. Yet, it is currently unclear how naturally occurring variation in mtDNA contributes to heterogeneity in infection outcomes. In this review article, we describe potential sources of variation in mitochondrial function that may arise due to mutations in vital nuclear and mitochondrial components of energy production or due to a disruption in mito-nuclear crosstalk. We then highlight how these changes in mitochondrial function can impact immune responses, focusing on their effects on ATP- and ROS-generating pathways, as well as immune signaling. Finally, we outline how being a powerful and genetically tractable model of infection, immunity and mitochondrial genetics makes the fruit fly Drosophila melanogaster ideally suited to dissect mitochondrial effects on innate immune responses to infection.
Collapse
Affiliation(s)
- Tiina S. Salminen
- School of Biological Sciences, Institute of Evolutionary Biology, The University of Edinburgh, Edinburgh, United Kingdom
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Pedro F. Vale
- School of Biological Sciences, Institute of Evolutionary Biology, The University of Edinburgh, Edinburgh, United Kingdom
| |
Collapse
|
32
|
Vaught RC, Voigt S, Dobler R, Clancy DJ, Reinhardt K, Dowling DK. Interactions between cytoplasmic and nuclear genomes confer sex-specific effects on lifespan in Drosophila melanogaster. J Evol Biol 2020; 33:694-713. [PMID: 32053259 DOI: 10.1111/jeb.13605] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 02/04/2020] [Accepted: 02/06/2020] [Indexed: 12/19/2022]
Abstract
Genetic variation outside of the cell nucleus can affect the phenotype. The cytoplasm is home to the mitochondria, and in arthropods often hosts intracellular bacteria such as Wolbachia. Although numerous studies have implicated epistatic interactions between cytoplasmic and nuclear genetic variation as mediators of phenotypic expression, two questions remain. Firstly, it remains unclear whether outcomes of cyto-nuclear interactions will manifest differently across the sexes, as might be predicted given that cytoplasmic genomes are screened by natural selection only through females as a consequence of their maternal inheritance. Secondly, the relative contribution of mitochondrial genetic variation to other cytoplasmic sources of variation, such as Wolbachia infection, in shaping phenotypic outcomes of cyto-nuclear interactions remains unknown. Here, we address these questions, creating a fully crossed set of replicated cyto-nuclear populations derived from three geographically distinct populations of Drosophila melanogaster, measuring the lifespan of males and females from each population. We observed that cyto-nuclear interactions shape lifespan and that the outcomes of these interactions differ across the sexes. Yet, we found no evidence that placing the cytoplasms from one population alongside the nuclear background of others (generating putative cyto-nuclear mismatches) leads to decreased lifespan in either sex. Although it was difficult to partition mitochondrial from Wolbachia effects, our results suggest at least some of the cytoplasmic genotypic contribution to lifespan was directly mediated by an effect of sequence variation in the mtDNA. Future work should explore the degree to which cyto-nuclear interactions result in sex differences in the expression of other components of organismal life history.
Collapse
Affiliation(s)
- Rebecca C Vaught
- School of Biological Sciences, Monash University, Clayton, VIC, Australia
| | - Susanne Voigt
- Faculty of Biology, Applied Zoology, TU Dresden, Dresden, Germany
| | - Ralph Dobler
- Faculty of Biology, Applied Zoology, TU Dresden, Dresden, Germany
| | - David J Clancy
- Division of Biomedical and Life Sciences, School of Health and Medicine, Lancaster University, Lancaster, UK
| | - Klaus Reinhardt
- Faculty of Biology, Applied Zoology, TU Dresden, Dresden, Germany
| | - Damian K Dowling
- School of Biological Sciences, Monash University, Clayton, VIC, Australia
| |
Collapse
|
33
|
Camus MF, Moore J, Reuter M. Nutritional geometry of mitochondrial genetic effects on male fertility. Biol Lett 2020; 16:20190891. [PMID: 32097597 DOI: 10.1098/rsbl.2019.0891] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Organismal fitness is partly determined by how well the nutritional intake matches sex-specific metabolic requirements. Metabolism itself is underpinned by complex genomic interactions involving products from both nuclear and mitochondrial genomes. Products from these two genomes must coordinate how nutrients are extracted, used and recycled, processes vital for fuelling reproduction. Given the complicated nature of metabolism, it is not well understood how the functioning of these two genomes is modulated by nutrients. Here we use nutritional geometry techniques on Drosophila lines that only differ in their mtDNA, with the aim to understand if there is nutrient-dependent mitochondrial genetic variance for male reproduction. We first find genetic variance for diet consumption, indicating that flies are consuming different amounts of food to meet new physiological requirements. We then find an interaction between mtDNA and diet for fitness, suggesting that the mtDNA plays a role in modulating diet-dependent fitness. Our results enhance our basic understanding of nutritional health and our chimeric genomes.
Collapse
Affiliation(s)
- M F Camus
- Research Department of Genetics, Evolution and Environment, University College, Gower Street, London WC1E 6BT, UK
| | - J Moore
- Research Department of Genetics, Evolution and Environment, University College, Gower Street, London WC1E 6BT, UK
| | - M Reuter
- Research Department of Genetics, Evolution and Environment, University College, Gower Street, London WC1E 6BT, UK
| |
Collapse
|
34
|
Montooth KL, Dhawanjewar AS, Meiklejohn CD. Temperature-Sensitive Reproduction and the Physiological and Evolutionary Potential for Mother's Curse. Integr Comp Biol 2020; 59:890-899. [PMID: 31173136 PMCID: PMC6797906 DOI: 10.1093/icb/icz091] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Strict maternal transmission of mitochondrial DNA (mtDNA) is hypothesized to permit the accumulation of mitochondrial variants that are deleterious to males but not females, a phenomenon called mother’s curse. However, direct evidence that mtDNA mutations exhibit such sexually antagonistic fitness effects is sparse. Male-specific mutational effects can occur when the physiological requirements of the mitochondria differ between the sexes. Such male-specific effects could potentially occur if sex-specific cell types or tissues have energy requirements that are differentially impacted by mutations affecting energy metabolism. Here we summarize findings from a model mitochondrial–nuclear incompatibility in the fruit fly Drosophila that demonstrates sex-biased effects, but with deleterious effects that are generally larger in females. We present new results showing that the mitochondrial–nuclear incompatibility does negatively affect male fertility, but only when males are developed at high temperatures. The temperature-dependent male sterility can be partially rescued by diet, suggesting an energetic basis. Finally, we discuss fruitful paths forward in understanding the physiological scope for sex-specific effects of mitochondrial mutations in the context of the recent discovery that many aspects of metabolism are sexually dimorphic and downstream of sex-determination pathways in Drosophila. A key parameter of these models that remains to be quantified is the fraction of mitochondrial mutations with truly male-limited fitness effects across extrinsic and intrinsic environments. Given the energy demands of reproduction in females, only a small fraction of the mitochondrial mutational spectrum may have the potential to contribute to mother’s curse in natural populations.
Collapse
Affiliation(s)
- Kristi L Montooth
- School of Biological Sciences, University of Nebraska-Lincoln, 1104 T Street, Lincoln, NE 68502, USA
| | - Abhilesh S Dhawanjewar
- School of Biological Sciences, University of Nebraska-Lincoln, 1104 T Street, Lincoln, NE 68502, USA
| | - Colin D Meiklejohn
- School of Biological Sciences, University of Nebraska-Lincoln, 1104 T Street, Lincoln, NE 68502, USA
| |
Collapse
|
35
|
Dowling DK, Adrian RE. Challenges and Prospects for Testing the Mother's Curse Hypothesis. Integr Comp Biol 2020; 59:875-889. [PMID: 31225591 DOI: 10.1093/icb/icz110] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Maternal inheritance of mitochondrial DNA (mtDNA) renders selection blind to mutations whose effects are limited to males. Evolutionary theory predicts this will lead to the accumulation of a male-specific genetic load within the mitochondrial genomes of populations; that is, a pool of mutations that negatively affects male, but not female, fitness components. This principle has been termed the Mother's Curse hypothesis. While the hypothesis has received some empirical support, its relevance to natural populations of metazoans remains unclear, and these ambiguities are compounded by the lack of a clear predictive framework for studies attempting to test Mother's Curse. Here, we seek to redress this by outlining the core predictions of the hypothesis, as well as the key features of the experimental designs that are required to enable direct testing of the predictions. Our goal is to provide a roadmap for future research seeking to elucidate the evolutionary significance of the Mother's Curse hypothesis.
Collapse
Affiliation(s)
- Damian K Dowling
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Rebecca E Adrian
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
| |
Collapse
|
36
|
Tobler M, Barts N, Greenway R. Mitochondria and the Origin of Species: Bridging Genetic and Ecological Perspectives on Speciation Processes. Integr Comp Biol 2020; 59:900-911. [PMID: 31004483 DOI: 10.1093/icb/icz025] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Mitochondria have been known to be involved in speciation through the generation of Dobzhansky-Muller incompatibilities, where functionally neutral co-evolution between mitochondrial and nuclear genomes can cause dysfunction when alleles are recombined in hybrids. We propose that adaptive mitochondrial divergence between populations can not only produce intrinsic (Dobzhansky-Muller) incompatibilities, but could also contribute to reproductive isolation through natural and sexual selection against migrants, post-mating prezygotic isolation, as well as by causing extrinsic reductions in hybrid fitness. We describe how these reproductive isolating barriers can potentially arise through adaptive divergence of mitochondrial function in the absence of mito-nuclear coevolution, a departure from more established views. While a role for mitochondria in the speciation process appears promising, we also highlight critical gaps of knowledge: (1) many systems with a potential for mitochondrially-mediated reproductive isolation lack crucial evidence directly linking reproductive isolation and mitochondrial function; (2) it often remains to be seen if mitochondrial barriers are a driver or a consequence of reproductive isolation; (3) the presence of substantial gene flow in the presence of mito-nuclear incompatibilities raises questions whether such incompatibilities are strong enough to drive speciation to completion; and (4) it remains to be tested how mitochondrial effects on reproductive isolation compare when multiple mechanisms of reproductive isolation coincide. We hope this perspective and the proposed research plans help to inform future studies of mitochondrial adaptation in a manner that links genotypic changes to phenotypic adaptations, fitness, and reproductive isolation in natural systems, helping to clarify the importance of mitochondria in the formation and maintenance of biological diversity.
Collapse
Affiliation(s)
- M Tobler
- Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - N Barts
- Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| | - R Greenway
- Division of Biology, Kansas State University, Manhattan, KS 66506, USA
| |
Collapse
|
37
|
Pozzi A, Dowling DK. The Genomic Origins of Small Mitochondrial RNAs: Are They Transcribed by the Mitochondrial DNA or by Mitochondrial Pseudogenes within the Nucleus (NUMTs)? Genome Biol Evol 2020; 11:1883-1896. [PMID: 31218347 PMCID: PMC6619488 DOI: 10.1093/gbe/evz132] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2019] [Indexed: 02/06/2023] Open
Abstract
Several studies have linked mitochondrial genetic variation to phenotypic modifications; albeit the identity of the mitochondrial polymorphisms involved remains elusive. The search for these polymorphisms led to the discovery of small noncoding RNAs, which appear to be transcribed by the mitochondrial DNA ("small mitochondrial RNAs"). This contention is, however, controversial because the nuclear genome of most animals harbors mitochondrial pseudogenes (NUMTs) of identical sequence to regions of mtDNA, which could alternatively represent the source of these RNAs. To discern the likely contributions of the mitochondrial and nuclear genome to transcribing these small mitochondrial RNAs, we leverage data from six vertebrate species exhibiting markedly different levels of NUMT sequence. We explore whether abundances of small mitochondrial RNAs are associated with levels of NUMT sequence across species, or differences in tissue-specific mtDNA content within species. Evidence for the former would support the hypothesis these RNAs are primarily transcribed by NUMT sequence, whereas evidence for the latter would provide strong evidence for the counter hypothesis that these RNAs are transcribed directly by the mtDNA. No association exists between the abundance of small mitochondrial RNAs and NUMT levels across species. Moreover, a sizable proportion of transcripts map exclusively to the mtDNA sequence, even in species with highest NUMT levels. Conversely, tissue-specific abundances of small mitochondrial RNAs are strongly associated with the mtDNA content. These results support the hypothesis that small mitochondrial RNAs are primarily transcribed by the mitochondrial genome and that this capacity is conserved across Amniota and, most likely, across most metazoan lineages.
Collapse
Affiliation(s)
- Andrea Pozzi
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Damian K Dowling
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
| |
Collapse
|
38
|
Flood PJ, Theeuwen TPJM, Schneeberger K, Keizer P, Kruijer W, Severing E, Kouklas E, Hageman JA, Wijfjes R, Calvo-Baltanas V, Becker FFM, Schnabel SK, Willems LAJ, Ligterink W, van Arkel J, Mumm R, Gualberto JM, Savage L, Kramer DM, Keurentjes JJB, van Eeuwijk F, Koornneef M, Harbinson J, Aarts MGM, Wijnker E. Reciprocal cybrids reveal how organellar genomes affect plant phenotypes. NATURE PLANTS 2020; 6:13-21. [PMID: 31932677 DOI: 10.1038/s41477-019-0575-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 11/25/2019] [Indexed: 05/21/2023]
Abstract
Assessment of the impact of variation in chloroplast and mitochondrial DNA (collectively termed the plasmotype) on plant phenotypes is challenging due to the difficulty in separating their effect from nuclear-derived variation (the nucleotype). Haploid-inducer lines can be used as efficient plasmotype donors to generate new plasmotype-nucleotype combinations (cybrids)1. We generated a panel comprising all possible cybrids of seven Arabidopsis thaliana accessions and extensively phenotyped these lines for 1,859 phenotypes under both stable and fluctuating conditions. We show that natural variation in the plasmotype results in both additive and epistatic effects across all phenotypic categories. Plasmotypes that induce more additive phenotypic changes also cause more epistatic effects, suggesting a possible common basis for both additive and epistatic effects. On average, epistatic interactions explained twice as much of the variance in phenotypes as additive plasmotype effects. The impact of plasmotypic variation was also more pronounced under fluctuating and stressful environmental conditions. Thus, the phenotypic impact of variation in plasmotypes is the outcome of multi-level nucleotype-plasmotype-environment interactions and, as such, the plasmotype is likely to serve as a reservoir of variation that is predominantly exposed under certain conditions. The production of cybrids using haploid inducers is a rapid and precise method for assessment of the phenotypic effects of natural variation in organellar genomes. It will facilitate efficient screening of unique nucleotype-plasmotype combinations to both improve our understanding of natural variation in these combinations and identify favourable combinations to enhance plant performance.
Collapse
Affiliation(s)
- Pádraic J Flood
- Laboratory of Genetics, Wageningen University & Research, Wageningen, the Netherlands.
- Horticulture and Product Physiology, Wageningen University & Research, Wageningen, the Netherlands.
- Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Cologne, Germany.
| | - Tom P J M Theeuwen
- Laboratory of Genetics, Wageningen University & Research, Wageningen, the Netherlands.
| | - Korbinian Schneeberger
- Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Paul Keizer
- Biometris, Wageningen University & Research, Wageningen, the Netherlands
| | - Willem Kruijer
- Biometris, Wageningen University & Research, Wageningen, the Netherlands
| | - Edouard Severing
- Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Evangelos Kouklas
- Laboratory of Genetics, Wageningen University & Research, Wageningen, the Netherlands
| | - Jos A Hageman
- Biometris, Wageningen University & Research, Wageningen, the Netherlands
| | - Raúl Wijfjes
- Bioinformatics Group, Wageningen, the Netherlands
| | - Vanesa Calvo-Baltanas
- Laboratory of Genetics, Wageningen University & Research, Wageningen, the Netherlands
| | - Frank F M Becker
- Laboratory of Genetics, Wageningen University & Research, Wageningen, the Netherlands
| | - Sabine K Schnabel
- Biometris, Wageningen University & Research, Wageningen, the Netherlands
| | - Leo A J Willems
- Laboratory of Plant Physiology, Wageningen University & Research, Wageningen, the Netherlands
| | - Wilco Ligterink
- Laboratory of Plant Physiology, Wageningen University & Research, Wageningen, the Netherlands
| | - Jeroen van Arkel
- Bioscience, Wageningen University & Research, Wageningen, the Netherlands
| | - Roland Mumm
- Bioscience, Wageningen University & Research, Wageningen, the Netherlands
| | - José M Gualberto
- Institut de Biologie Moléculaire des Plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Linda Savage
- MSU-DOE Plant Research Lab, Michigan State University, East Lansing, MI, USA
| | - David M Kramer
- MSU-DOE Plant Research Lab, Michigan State University, East Lansing, MI, USA
| | - Joost J B Keurentjes
- Laboratory of Genetics, Wageningen University & Research, Wageningen, the Netherlands
| | - Fred van Eeuwijk
- Biometris, Wageningen University & Research, Wageningen, the Netherlands
| | - Maarten Koornneef
- Laboratory of Genetics, Wageningen University & Research, Wageningen, the Netherlands
- Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Jeremy Harbinson
- Horticulture and Product Physiology, Wageningen University & Research, Wageningen, the Netherlands
| | - Mark G M Aarts
- Laboratory of Genetics, Wageningen University & Research, Wageningen, the Netherlands
| | - Erik Wijnker
- Laboratory of Genetics, Wageningen University & Research, Wageningen, the Netherlands.
| |
Collapse
|
39
|
Camus MF, O'Leary M, Reuter M, Lane N. Impact of mitonuclear interactions on life-history responses to diet. Philos Trans R Soc Lond B Biol Sci 2019; 375:20190416. [PMID: 31787037 DOI: 10.1098/rstb.2019.0416] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mitochondria are central to both energy metabolism and biosynthesis. Mitochondrial function could therefore influence resource allocation. Critically, mitochondrial function depends on interactions between proteins encoded by the mitochondrial and nuclear genomes. Severe incompatibilities between these genomes can have pervasive effects on both fitness and longevity. How milder deficits in mitochondrial function affect life-history trade-offs is less well understood. Here, we analyse how mitonuclear interactions affect the trade-off between fecundity and longevity in Drosophila melanogaster. We consider a panel of 10 different mitochondrial DNA haplotypes against two contrasting nuclear backgrounds (w1118 (WE) and Zim53 (ZIM)) in response to high-protein versus standard diet. We report strikingly different responses between the two nuclear backgrounds. WE females have higher fecundity and decreased longevity on high protein. ZIM females have much greater fecundity and shorter lifespan than WE flies on standard diet. High protein doubled their fecundity with no effect on longevity. Mitochondrial haplotype reflected nuclear life-history trade-offs, with a negative correlation between longevity and fecundity in WE flies and no correlation in ZIM flies. Mitonuclear interactions had substantial effects but did not reflect genetic distance between mitochondrial haplotypes. We conclude that mitonuclear interactions can have significant impact on life-history trade-offs, but their effects are not predictable by relatedness. This article is part of the theme issue 'Linking the mitochondrial genotype to phenotype: a complex endeavour'.
Collapse
Affiliation(s)
- M Florencia Camus
- Research Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
| | - Michael O'Leary
- Research Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
| | - Max Reuter
- Research Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
| | - Nick Lane
- Research Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
| |
Collapse
|
40
|
Rand DM, Mossman JA. Mitonuclear conflict and cooperation govern the integration of genotypes, phenotypes and environments. Philos Trans R Soc Lond B Biol Sci 2019; 375:20190188. [PMID: 31787039 PMCID: PMC6939372 DOI: 10.1098/rstb.2019.0188] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The mitonuclear genome is the most successful co-evolved mutualism in the history of life on Earth. The cross-talk between the mitochondrial and nuclear genomes has been shaped by conflict and cooperation for more than 1.5 billion years, yet this system has adapted to countless genomic reorganizations by each partner, and done so under changing environments that have placed dramatic biochemical and physiological pressures on evolving lineages. From putative anaerobic origins, mitochondria emerged as the defining aerobic organelle. During this transition, the two genomes resolved rules for sex determination and transmission that made uniparental inheritance the dominant, but not a universal pattern. Mitochondria are much more than energy-producing organelles and play crucial roles in nutrient and stress signalling that can alter how nuclear genes are expressed as phenotypes. All of these interactions are examples of genotype-by-environment (GxE) interactions, gene-by-gene (GxG) interactions (epistasis) or more generally context-dependent effects on the link between genotype and phenotype. We provide evidence from our own studies in Drosophila, and from those of other systems, that mitonuclear interactions—either conflicting or cooperative—are common features of GxE and GxG. We argue that mitonuclear interactions are an important model for how to better understand the pervasive context-dependent effects underlying the architecture of complex phenotypes. Future research in this area should focus on the quantitative genetic concept of effect size to place mitochondrial links to phenotype in a proper context. This article is part of the theme issue ‘Linking the mitochondrial genotype to phenotype: a complex endeavour’.
Collapse
Affiliation(s)
- David M Rand
- Department of Ecology and Evolutionary Biology, Brown University, 80 Waterman Street, Box G, Providence, RI, USA
| | - Jim A Mossman
- Department of Ecology and Evolutionary Biology, Brown University, 80 Waterman Street, Box G, Providence, RI, USA
| |
Collapse
|
41
|
Nagarajan-Radha V, Aitkenhead I, Clancy DJ, Chown SL, Dowling DK. Sex-specific effects of mitochondrial haplotype on metabolic rate in Drosophila melanogaster support predictions of the Mother's Curse hypothesis. Philos Trans R Soc Lond B Biol Sci 2019; 375:20190178. [PMID: 31787038 DOI: 10.1098/rstb.2019.0178] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Evolutionary theory proposes that maternal inheritance of mitochondria will facilitate the accumulation of mitochondrial DNA (mtDNA) mutations that are harmful to males but benign or beneficial to females. Furthermore, mtDNA haplotypes sampled from across a given species distribution are expected to differ in the number and identity of these 'male-harming' mutations they accumulate. Consequently, it is predicted that the genetic variation which delineates distinct mtDNA haplotypes of a given species should confer larger phenotypic effects on males than females (reflecting mtDNA mutations that are male-harming, but female-benign), or sexually antagonistic effects (reflecting mutations that are male-harming, but female-benefitting). These predictions have received support from recent work examining mitochondrial haplotypic effects on adult life-history traits in Drosophila melanogaster. Here, we explore whether similar signatures of male-bias or sexual antagonism extend to a key physiological trait-metabolic rate. We measured the effects of mitochondrial haplotypes on the amount of carbon dioxide produced by individual flies, controlling for mass and activity, across 13 strains of D. melanogaster that differed only in their mtDNA haplotype. The effects of mtDNA haplotype on metabolic rate were larger in males than females. Furthermore, we observed a negative intersexual correlation across the haplotypes for metabolic rate. Finally, we uncovered a male-specific negative correlation, across haplotypes, between metabolic rate and longevity. These results are consistent with the hypothesis that maternal mitochondrial inheritance has led to the accumulation of a sex-specific genetic load within the mitochondrial genome, which affects metabolic rate and that may have consequences for the evolution of sex differences in life history. This article is part of the theme issue 'Linking the mitochondrial genotype to phenotype: a complex endeavour'.
Collapse
Affiliation(s)
| | - Ian Aitkenhead
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - David J Clancy
- Division of Biomedical and Life Sciences, Faculty of Health and Medicine, Lancaster University, Lancaster, UK
| | - Steven L Chown
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Damian K Dowling
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
| |
Collapse
|
42
|
Bevers RPJ, Litovchenko M, Kapopoulou A, Braman VS, Robinson MR, Auwerx J, Hollis B, Deplancke B. Mitochondrial haplotypes affect metabolic phenotypes in the Drosophila Genetic Reference Panel. Nat Metab 2019; 1:1226-1242. [PMID: 32694676 DOI: 10.1038/s42255-019-0147-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 11/07/2019] [Indexed: 01/04/2023]
Abstract
The nature and extent of mitochondrial DNA variation in a population and how it affects traits is poorly understood. Here we resequence the mitochondrial genomes of 169 Drosophila Genetic Reference Panel lines, identifying 231 variants that stratify along 12 mitochondrial haplotypes. We identify 1,845 cases of mitonuclear allelic imbalances, thus implying that mitochondrial haplotypes are reflected in the nuclear genome. However, no major fitness effects are associated with mitonuclear imbalance, suggesting that such imbalances reflect population structure at the mitochondrial level rather than genomic incompatibilities. Although mitochondrial haplotypes have no direct impact on mitochondrial respiration, some haplotypes are associated with stress- and metabolism-related phenotypes, including food intake in males. Finally, through reciprocal swapping of mitochondrial genomes, we demonstrate that a mitochondrial haplotype associated with high food intake can rescue a low food intake phenotype. Together, our findings provide new insight into population structure at the mitochondrial level and point to the importance of incorporating mitochondrial haplotypes in genotype-phenotype relationship studies.
Collapse
Affiliation(s)
- Roel P J Bevers
- Laboratory of Systems Biology and Genetics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
- Genomics England, London, UK
| | - Maria Litovchenko
- Laboratory of Systems Biology and Genetics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Adamandia Kapopoulou
- Laboratory of Systems Biology and Genetics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Virginie S Braman
- Laboratory of Systems Biology and Genetics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Matthew R Robinson
- Complex Trait Genetics Group, Université de Lausanne, Lausanne, Switzerland
| | - Johan Auwerx
- Laboratory of Integrative Systems Physiology, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Brian Hollis
- Laboratory of Systems Biology and Genetics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Bart Deplancke
- Laboratory of Systems Biology and Genetics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
- Swiss Institute of Bioinformatics, Lausanne, Switzerland.
| |
Collapse
|
43
|
Keaney TA, Wong HWS, Dowling DK, Jones TM, Holman L. Mother’s curse and indirect genetic effects: Do males matter to mitochondrial genome evolution? J Evol Biol 2019; 33:189-201. [DOI: 10.1111/jeb.13561] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 10/07/2019] [Accepted: 10/10/2019] [Indexed: 12/11/2022]
Affiliation(s)
- Thomas A. Keaney
- School of Biosciences The University of Melbourne Melbourne Victoria Australia
| | - Heidi W. S. Wong
- School of Biosciences The University of Melbourne Melbourne Victoria Australia
| | - Damian K. Dowling
- School of Biological Sciences Monash University Clayton Victoria Australia
| | - Therésa M. Jones
- School of Biosciences The University of Melbourne Melbourne Victoria Australia
| | - Luke Holman
- School of Biosciences The University of Melbourne Melbourne Victoria Australia
| |
Collapse
|
44
|
Dong W, Dobler R, Dowling DK, Moussian B. The cuticle inward barrier in Drosophila melanogaster is shaped by mitochondrial and nuclear genotypes and a sex-specific effect of diet. PeerJ 2019; 7:e7802. [PMID: 31592352 PMCID: PMC6779114 DOI: 10.7717/peerj.7802] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2019] [Accepted: 08/31/2019] [Indexed: 01/23/2023] Open
Abstract
An important role of the insect cuticle is to prevent wetting (i.e., permeation of water) and also to prevent penetration of potentially harmful substances. This barrier function mainly depends on the hydrophobic cuticle surface composed of lipids including cuticular hydrocarbons (CHCs). We investigated to what extent the cuticle inward barrier function depends on the genotype, comprising mitochondrial and nuclear genes in the fruit fly Drosophila melanogaster, and investigated the contribution of interactions between mitochondrial and nuclear genotypes (mito-nuclear interactions) on this function. In addition, we assessed the effects of nutrition and sex on the cuticle barrier function. Based on a dye penetration assay, we find that cuticle barrier function varies across three fly lines that were captured from geographically separated regions in three continents. Testing different combinations of mito-nuclear genotypes, we show that the inward barrier efficiency is modulated by the nuclear and mitochondrial genomes independently. We also find an interaction between diet and sex. Our findings provide new insights into the regulation of cuticle inward barrier function in nature.
Collapse
Affiliation(s)
- Wei Dong
- Institute of Applied Biology, Shanxi University, Taiyuan, China.,Applied Zoology, Faculty of Biology, Technische Universität Dresden, Dresden, Germany
| | - Ralph Dobler
- Applied Zoology, Faculty of Biology, Technische Universität Dresden, Dresden, Germany
| | - Damian K Dowling
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
| | - Bernard Moussian
- Institute of Applied Biology, Shanxi University, Taiyuan, China.,Applied Zoology, Faculty of Biology, Technische Universität Dresden, Dresden, Germany.,Université Côte d'Azur, CNRS-Inserm, iBV, Parc Valrose, Nice, France
| |
Collapse
|
45
|
Mossman JA, Biancani LM, Rand DM. Mitochondrial genomic variation drives differential nuclear gene expression in discrete regions of Drosophila gene and protein interaction networks. BMC Genomics 2019; 20:691. [PMID: 31477008 PMCID: PMC6719383 DOI: 10.1186/s12864-019-6061-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Accepted: 08/26/2019] [Indexed: 12/12/2022] Open
Abstract
Background Mitochondria perform many key roles in their eukaryotic hosts, from integrating signaling pathways through to modulating whole organism phenotypes. The > 1 billion years of nuclear and mitochondrial gene co-evolution has necessitated coordinated expression of gene products from both genomes that maintain mitochondrial, and more generally, eukaryotic cellular function. How mitochondrial DNA (mtDNA) variation modifies host fitness has proved a challenging question but has profound implications for evolutionary and medical genetics. In Drosophila, we have previously shown that recently diverged mtDNA haplotypes within-species can have more impact on organismal phenotypes than older, deeply diverged haplotypes from different species. Here, we tested the effects of mtDNA haplotype variation on gene expression in Drosophila under standardized conditions. Using the Drosophila Genetic Reference Panel (DGRP), we constructed a panel of mitonuclear genotypes that consists of factorial variation in nuclear and mtDNA genomes, with mtDNAs originating in D. melanogaster (2x haplotypes) and D. simulans (2x haplotypes). Results We show that mtDNA haplotype variation unequivocally alters nuclear gene expression in both females and males, and mitonuclear interactions are pervasive modifying factors for gene expression. There was appreciable overlap between the sexes for mtDNA-sensitive genes, and considerable transcriptional variation attributed to particular mtDNA contrasts. These genes are generally found in low-connectivity gene co-expression networks, occur in gene clusters along chromosomes, are often flanked by non-coding RNA, and are under-represented among housekeeping genes. Finally, we identify the giant (gt) transcription factor motif as a putative regulatory sequence associated with mtDNA-sensitive genes. Conclusions There are predictive conditions for nuclear genes that are influenced by mtDNA variation. Electronic supplementary material The online version of this article (10.1186/s12864-019-6061-y) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Jim A Mossman
- Department of Ecology and Evolutionary Biology, Box G, Brown University, Providence, RI, 02912, USA.
| | - Leann M Biancani
- Department of Ecology and Evolutionary Biology, Box G, Brown University, Providence, RI, 02912, USA.,Present Address: Department of Biology, University of Maryland, College Park, MD, 20742, USA
| | - David M Rand
- Department of Ecology and Evolutionary Biology, Box G, Brown University, Providence, RI, 02912, USA.
| |
Collapse
|
46
|
Sujkowski A, Spierer AN, Rajagopalan T, Bazzell B, Safdar M, Imsirovic D, Arking R, Rand DM, Wessells R. Mito-nuclear interactions modify Drosophila exercise performance. Mitochondrion 2019; 47:188-205. [PMID: 30408593 PMCID: PMC7035791 DOI: 10.1016/j.mito.2018.11.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 10/19/2018] [Accepted: 11/03/2018] [Indexed: 02/08/2023]
Abstract
Endurance exercise has received increasing attention as a broadly preventative measure against age-related disease and dysfunction. Improvement of mitochondrial quality by enhancement of mitochondrial turnover is thought to be among the important molecular mechanisms underpinning the benefits of exercise. Interactions between the mitochondrial and nuclear genomes are important components of the genetic basis for variation in longevity, fitness and the incidence of disease. Here, we examine the effects of replacing the mitochondrial genome (mtDNA) of several Drosophila strains with mtDNA from other strains, or from closely related species, on exercise performance. We find that mitochondria from flies selected for longevity increase the performance of flies from a parental strain. We also find evidence that mitochondria from other strains or species alter exercise performance, with examples of both beneficial and deleterious effects. These findings suggest that both the mitochondrial and nuclear genomes, as well as interactions between the two, contribute significantly to exercise capacity.
Collapse
Affiliation(s)
- Alyson Sujkowski
- Department of Physiology, Wayne State University, Detroit, MI, United States
| | - Adam N Spierer
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, United States
| | - Thiviya Rajagopalan
- Department of Physiology, Wayne State University, Detroit, MI, United States
| | - Brian Bazzell
- Department of Physiology, Wayne State University, Detroit, MI, United States
| | - Maryam Safdar
- Department of Physiology, Wayne State University, Detroit, MI, United States
| | - Dinko Imsirovic
- Department of Physiology, Wayne State University, Detroit, MI, United States
| | - Robert Arking
- Department of Biological Sciences, Wayne State University, Detroit, MI, United States
| | - David M Rand
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, United States
| | - Robert Wessells
- Department of Physiology, Wayne State University, Detroit, MI, United States.
| |
Collapse
|
47
|
Drummond E, Short E, Clancy D. Mitonuclear gene X environment effects on lifespan and health: How common, how big? Mitochondrion 2019; 49:12-18. [PMID: 31254634 DOI: 10.1016/j.mito.2019.06.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 05/16/2019] [Accepted: 06/25/2019] [Indexed: 01/13/2023]
Abstract
Mitochondrial genetic variation can have profound effects on fitness, and the mitotype must interact with both the nuclear genes and the environment. We used Drosophila to investigate the extent to which mitotype effects on lifespan and activity are modulated by nucleotype and environmental variation. When nucleotype is varied, mitochondrial effects on lifespan persisted but were relatively small, and still male biased. Varying food as well, mitotype had substantial effects on male climbing speed, modifiable by nucleotype but less so by diet. Finally, mitotype affected fly lifespan much more in a cage environment compared with a vial, also modifiable by nucleotype and diet. The cage may represent a stressful environment. Mitochondrial genotype may affect fitness much more in conditions of stress, which may have implications for human health.
Collapse
Affiliation(s)
- Emma Drummond
- Division of Biomedical and Life Sciences, Lancaster University, Lancaster LA1 4YQ, United Kingdom
| | - Emma Short
- Division of Biomedical and Life Sciences, Lancaster University, Lancaster LA1 4YQ, United Kingdom
| | - David Clancy
- Division of Biomedical and Life Sciences, Lancaster University, Lancaster LA1 4YQ, United Kingdom.
| |
Collapse
|
48
|
Abstract
Mitochondria, a nearly ubiquitous feature of eukaryotes, are derived from an ancient symbiosis. Despite billions of years of cooperative coevolution - in what is arguably the most important mutualism in the history of life - the persistence of mitochondrial genomes also creates conditions for genetic conflict with the nucleus. Because mitochondrial genomes are present in numerous copies per cell, they are subject to both within- and among-organism levels of selection. Accordingly, 'selfish' genotypes that increase their own proliferation can rise to high frequencies even if they decrease organismal fitness. It has been argued that uniparental (often maternal) inheritance of cytoplasmic genomes evolved to curtail such selfish replication by minimizing within-individual variation and, hence, within-individual selection. However, uniparental inheritance creates conditions for cytonuclear conflict over sex determination and sex ratio, as well as conditions for sexual antagonism when mitochondrial variants increase transmission by enhancing maternal fitness but have the side-effect of being harmful to males (i.e., 'mother's curse'). Here, we review recent advances in understanding selfish replication and sexual antagonism in the evolution of mitochondrial genomes and the mechanisms that suppress selfish interactions, drawing parallels and contrasts with other organelles (plastids) and bacterial endosymbionts that arose more recently. Although cytonuclear conflict is widespread across eukaryotes, it can be cryptic due to nuclear suppression, highly variable, and lineage-specific, reflecting the diverse biology of eukaryotes and the varying architectures of their cytoplasmic genomes.
Collapse
Affiliation(s)
- Justin C Havird
- Department of Integrative Biology, The University of Texas, Austin, TX 78712, USA.
| | - Evan S Forsythe
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Alissa M Williams
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - John H Werren
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
| | - Damian K Dowling
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Daniel B Sloan
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| |
Collapse
|
49
|
Hill GE, Havird JC, Sloan DB, Burton RS, Greening C, Dowling DK. Assessing the fitness consequences of mitonuclear interactions in natural populations. Biol Rev Camb Philos Soc 2019; 94:1089-1104. [PMID: 30588726 PMCID: PMC6613652 DOI: 10.1111/brv.12493] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Revised: 11/27/2018] [Accepted: 11/30/2018] [Indexed: 12/22/2022]
Abstract
Metazoans exist only with a continuous and rich supply of chemical energy from oxidative phosphorylation in mitochondria. The oxidative phosphorylation machinery that mediates energy conservation is encoded by both mitochondrial and nuclear genes, and hence the products of these two genomes must interact closely to achieve coordinated function of core respiratory processes. It follows that selection for efficient respiration will lead to selection for compatible combinations of mitochondrial and nuclear genotypes, and this should facilitate coadaptation between mitochondrial and nuclear genomes (mitonuclear coadaptation). Herein, we outline the modes by which mitochondrial and nuclear genomes may coevolve within natural populations, and we discuss the implications of mitonuclear coadaptation for diverse fields of study in the biological sciences. We identify five themes in the study of mitonuclear interactions that provide a roadmap for both ecological and biomedical studies seeking to measure the contribution of intergenomic coadaptation to the evolution of natural populations. We also explore the wider implications of the fitness consequences of mitonuclear interactions, focusing on central debates within the fields of ecology and biomedicine.
Collapse
Affiliation(s)
- Geoffrey E. Hill
- Department of Biological Sciences, Auburn University, United States of America
| | - Justin C. Havird
- Department of Biology, Colorado State University, United States of America
| | - Daniel B. Sloan
- Department of Biology, Colorado State University, United States of America
| | - Ronald S. Burton
- Scripps Institution of Oceanography, University of California, San Diego, United States of America
| | - Chris Greening
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Damian K. Dowling
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
| |
Collapse
|
50
|
Camus MF, Dowling DK. Mitochondrial genetic effects on reproductive success: signatures of positive intrasexual, but negative intersexual pleiotropy. Proc Biol Sci 2019; 285:rspb.2018.0187. [PMID: 29794041 DOI: 10.1098/rspb.2018.0187] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 04/30/2018] [Indexed: 01/03/2023] Open
Abstract
Theory predicts that maternal inheritance of mitochondria will facilitate the accumulation of mtDNA mutations that are male biased, or even sexually antagonistic, in effect. While there are many reported cases of mtDNA mutations conferring cytoplasmic male sterility in plants, historically it was assumed such mutations would not persist in the streamlined mitochondrial genomes of bilaterian metazoans. Intriguingly, recent cases of mitochondrial variants exerting male biases in effect have come to light in bilaterians. These cases aside, it remains unknown whether the mitochondrial genetic variation affecting phenotypic expression, and in particular reproductive performance, in bilaterians is routinely composed of sex-biased or sex-specific variation. If selection consistently favours mtDNA variants that augment female fitness, but at cost to males, this could shape patterns of pleiotropy and lead to negative intersexual correlations across mtDNA haplotypes. Here, we show that genetic variation across naturally occurring mitochondrial haplotypes affects components of reproductive success in both sexes, in the fruit fly Drosophila melanogaster We find that intrasexual correlations across mitochondrial haplotypes, for components of reproductive success, are generally positive, while intersexual correlations are negative. These results accord with theoretical predictions, suggesting that maternal inheritance has led to the fixation of numerous mutations of sexually antagonistic effect.
Collapse
Affiliation(s)
- M Florencia Camus
- School of Biological Sciences, Monash University, Victoria 3800, Australia .,Research Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
| | - Damian K Dowling
- School of Biological Sciences, Monash University, Victoria 3800, Australia
| |
Collapse
|