1
|
Casagrande S, Dzialo M, Trost L, Malkoc K, Sadowska ET, Hau M, Pierce B, McWilliams S, Bauchinger U. Mitochondrial metabolism in blood more reliably predicts whole-animal energy needs compared to other tissues. iScience 2023; 26:108321. [PMID: 38025793 PMCID: PMC10679813 DOI: 10.1016/j.isci.2023.108321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 09/18/2023] [Accepted: 10/20/2023] [Indexed: 12/01/2023] Open
Abstract
Understanding energy metabolism in free-ranging animals is crucial for ecological studies. In birds, red blood cells (RBCs) offer a minimally invasive method to estimate metabolic rate (MR). In this study with European starlings Sturnus vulgaris, we examined how RBC oxygen consumption relates to oxygen use in key tissues (brain, liver, heart, and pectoral muscle) and versus the whole organism measured at basal levels. The pectoral muscle accounted for 34%-42% of organismal MR, while the heart and liver, despite their high mass-specific metabolic rate, each contributed 2.5%-3.0% to organismal MR. Despite its low contribution to organismal MR (0.03%-0.04%), RBC MR best predicted organismal MR (r = 0.70). Oxygen consumption of the brain and pectoralis was also associated with whole-organism MR, unlike that of heart and liver. Overall, our findings demonstrate that the metabolism of a systemic tissue like blood is a superior proxy for organismal energy metabolism than that of other tissues.
Collapse
Affiliation(s)
- Stefania Casagrande
- Max Planck Institute for Biological Intelligence, Evolutionary Physiology Group, 82319 Seewiesen, Germany
| | - Maciej Dzialo
- Jagiellonian University, Institute of Environmental Sciences, 30-387 Kraków, Poland
| | - Lisa Trost
- Max Planck Institute for Biological Intelligence, Department for Behavioral Neurobiology, 82319 Seewiesen, Germany
| | - Kasja Malkoc
- Max Planck Institute for Biological Intelligence, Evolutionary Physiology Group, 82319 Seewiesen, Germany
| | | | - Michaela Hau
- Max Planck Institute for Biological Intelligence, Evolutionary Physiology Group, 82319 Seewiesen, Germany
- University of Konstanz, Department of Biology, 78464 Konstanz, Germany
| | - Barbara Pierce
- Sacred Heart University, Department of Biology, Fairfield, CT 06825, USA
| | - Scott McWilliams
- University of Rhode Island, Department of Natural Resources Science, Kingston, RI 02881, USA
| | - Ulf Bauchinger
- Jagiellonian University, Institute of Environmental Sciences, 30-387 Kraków, Poland
- Nencki Institute of Experimental Biology, PAS, 02-093 Warsaw, Poland
| |
Collapse
|
2
|
Lubawy J, Chowański SP, Colinet H, Słocińska M. Mitochondrial metabolism and oxidative stress in the tropical cockroach under fluctuating thermal regimes. J Exp Biol 2023; 226:jeb246287. [PMID: 37589559 DOI: 10.1242/jeb.246287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 08/08/2023] [Indexed: 08/18/2023]
Abstract
The cockroach Gromphadorhina coquereliana can survive at low temperatures under extensive periods of cold stress. To assess energy management and insect adaptation in response to cold, we measured mitochondrial activity and oxidative stress in muscle and fat body tissues from G. coquereliana under a fluctuating thermal regime (FTR; stressed at 4°C for 3 h on 3 consecutive days, with or without 24 h recovery). Compared with our earlier work showing that a single exposure to cold significantly affects mitochondrial parameters, here, repeated exposure to cold triggered an acclimatory response, resulting in unchanged mitochondrial bioenergetics. Immediately after cold exposure, we observed an increase in the overall pool of ATP and a decrease in typical antioxidant enzyme activity. We also observed decreased activity of uncoupling protein 4 in muscle mitochondria. After 24 h of recovery, we observed an increase in expression of antioxidant enzymes in muscles and the fat body and a significant increase in the expression of UCP4 and HSP70 in the latter. This indicates that processes related to energy conversion and disturbance under cold stress may trigger different protective mechanisms in these tissues, and that these mechanisms must be activated to restore insect homeostasis. The mitochondrial parameters and enzymatic assays suggest that mitochondria are not affected during FTR but oxidative stress markers are decreased, and a 24 h recovery period allows for the restoration of redox and energy homeostasis, especially in the fat body. This confirms the crucial role of the fat body in intermediary metabolism and energy management in insects and in the response to repeated thermal stress.
Collapse
Affiliation(s)
- Jan Lubawy
- Department of Animal Physiology and Developmental Biology, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University, 61-614 Poznań, Poland
| | - Szymon P Chowański
- Department of Animal Physiology and Developmental Biology, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University, 61-614 Poznań, Poland
| | - Hervé Colinet
- ECOBIO - UMR 6553, Université de Rennes 1, CNRS, Rennes 35042, France
| | - Małgorzata Słocińska
- Department of Animal Physiology and Developmental Biology, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University, 61-614 Poznań, Poland
| |
Collapse
|
3
|
Lebenzon JE, Overgaard J, Jørgensen LB. Chilled, starved or frozen: Insect mitochondrial adaptations to overcome the cold. CURRENT OPINION IN INSECT SCIENCE 2023:101076. [PMID: 37331596 DOI: 10.1016/j.cois.2023.101076] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 06/13/2023] [Accepted: 06/13/2023] [Indexed: 06/20/2023]
Abstract
Physiological adaptations to tackle cold exposure are crucial for insects living in temperate and arctic environments and here we review how cold adaptation is manifested in terms of mitochondrial function. Cold challenges are diverse, and different insect species have evolved metabolic and mitochondrial adaptations to: i) energize homeostatic regulation at low temperature, ii) stretch energy reserves during prolonged cold exposure, and iii) preserve structural organization of organelles following extracellular freezing. While the literature is still sparse, our review suggests that cold-adapted insects preserve ATP production at low temperatures by maintaining preferred mitochondrial substrate oxidation, which is otherwise challenged in cold-sensitive species. Chronic cold exposure and metabolic depression during dormancy is linked to reduced mitochondrial metabolism and may involve mitochondrial degradation. Finally, adaptation to extracellular freezing could be associated with superior structural integrity of the mitochondrial inner membrane following freezing which is linked to cellular and organismal survival.
Collapse
Affiliation(s)
- Jacqueline E Lebenzon
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
| | - Johannes Overgaard
- Section for Zoophysiology, Department of Biology, Aarhus University, 8000 Aarhus C, Denmark.
| | | |
Collapse
|
4
|
Sokolova IM. Ectotherm mitochondrial economy and responses to global warming. Acta Physiol (Oxf) 2023; 237:e13950. [PMID: 36790303 DOI: 10.1111/apha.13950] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 01/24/2023] [Accepted: 02/10/2023] [Indexed: 02/16/2023]
Abstract
Temperature is a key abiotic factor affecting ecology, biogeography, and evolution of species. Alterations of energy metabolism play an important role in adaptations and plastic responses to temperature shifts on different time scales. Mitochondrial metabolism affects cellular bioenergetics and redox balance making these organelles an important determinant of organismal performances such as growth, locomotion, or development. Here I analyze the impacts of environmental temperature on the mitochondrial functions (including oxidative phosphorylation, proton leak, production of reactive oxygen species(ROS), and ATP synthesis) of ectotherms and discuss the mechanisms underlying negative shifts in the mitochondrial energy economy caused by supraoptimal temperatures. Owing to the differences in the thermal sensitivity of different mitochondrial processes, elevated temperatures (beyond the species- and population-specific optimal range) cause reallocation of the electron flux and the protonmotive force (Δp) in a way that decreases ATP synthesis efficiency, elevates the relative cost of the mitochondrial maintenance, causes excessive production of ROS and raises energy cost for antioxidant defense. These shifts in the mitochondrial energy economy might have negative consequences for the organismal fitness traits such as the thermal tolerance or growth. Correlation between the thermal sensitivity indices of the mitochondria and the whole organism indicate that these traits experience similar selective pressures but further investigations are needed to establish whether there is a cause-effect relationship between the mitochondrial failure and loss of organismal performance during temperature change.
Collapse
Affiliation(s)
- Inna M Sokolova
- Department of Marine Biology, Institute of Biological Sciences, University of Rostock, Rostock, Germany
- Department of Maritime Systems, Interdisciplinary Faculty, University of Rostock, Rostock, Germany
| |
Collapse
|
5
|
Zhu W, Zhao C, Zhao T, Chang L, Chen Q, Liu J, Li C, Xie F, Jiang J. Rising floor and dropping ceiling: organ heterogeneity in response to cold acclimation of the largest extant amphibian. Proc Biol Sci 2022; 289:20221394. [PMID: 36196548 PMCID: PMC9532983 DOI: 10.1098/rspb.2022.1394] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Low temperature imposes strong selective pressure on ectotherms. To maximize their overall fitness under cold conditions, the ectotherms may either try to maintain their physiological activities through metabolic compensation or enter into metabolic depression; however, some species adopt both strategies to cope with different degrees of cold. Nevertheless, how these two seemingly opposite strategies are coordinated has rarely been elucidated. Here, we investigated the molecular strategy underlying the cold acclimation of Andrias davidianus, the largest extant amphibian, using multi-organ metabolomics and transcriptomics. The results showed remarkable organ heterogeneity in response to cold. While most organs showed transcriptional upregulation of metabolic processes, the heart exhibited downregulation. This heterogeneity explained the adaptive reorganization in resource allocation, which compensates for metabolic maintenance by compromising growth. Importantly, the cardiac function might constitute a ‘ceiling’ to constrain the space for compensation, especially under colder conditions. Additionally, the opposite transcriptional regulation of oxidative phosphorylation and other pathways might also shape the overall metabolic capacity under cold conditions. The heterogeneity in cold responses may have directed a shift in cold adaptive strategy from compensation to depression with a drop in temperature. These results provide a novel insight into the regulatory mechanisms underlying cold survival strategies of ectotherms.
Collapse
Affiliation(s)
- Wei Zhu
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chendgu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, People's Republic of China.,University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Chunlin Zhao
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chendgu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, People's Republic of China
| | - Tian Zhao
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chendgu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, People's Republic of China
| | - Liming Chang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chendgu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, People's Republic of China.,University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Qiheng Chen
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chendgu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, People's Republic of China.,University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Jiongyu Liu
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chendgu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, People's Republic of China
| | - Cheng Li
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chendgu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, People's Republic of China
| | - Feng Xie
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chendgu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, People's Republic of China
| | - Jianping Jiang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chendgu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, People's Republic of China.,University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| |
Collapse
|
6
|
Udino E, George JM, McKenzie M, Pessato A, Crino OL, Buchanan KL, Mariette MM. Prenatal acoustic programming of mitochondrial function for high temperatures in an arid-adapted bird. Proc Biol Sci 2021; 288:20211893. [PMID: 34875198 PMCID: PMC8651415 DOI: 10.1098/rspb.2021.1893] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 11/15/2021] [Indexed: 12/16/2022] Open
Abstract
Sound is an essential source of information in many taxa and can notably be used by embryos to programme their phenotypes for postnatal environments. While underlying mechanisms are mostly unknown, there is growing evidence for the involvement of mitochondria-main source of cellular energy (i.e. ATP)-in developmental programming processes. Here, we tested whether prenatal sound programmes mitochondrial metabolism. In the arid-adapted zebra finch, prenatal exposure to 'heat-calls'-produced by parents incubating at high temperatures-adaptively alters nestling growth in the heat. We measured red blood cell mitochondrial function, in nestlings exposed prenatally to heat- or control-calls, and reared in contrasting thermal environments. Exposure to high temperatures always reduced mitochondrial ATP production efficiency. However, as expected to reduce heat production, prenatal exposure to heat-calls improved mitochondrial efficiency under mild heat conditions. In addition, when exposed to an acute heat-challenge, LEAK respiration was higher in heat-call nestlings, and mitochondrial efficiency low across temperatures. Consistent with its role in reducing oxidative damage, LEAK under extreme heat was also higher in fast growing nestlings. Our study therefore provides the first demonstration of mitochondrial acoustic sensitivity, and brings us closer to understanding the underpinning of acoustic developmental programming and avian strategies for heat adaptation.
Collapse
Affiliation(s)
- Eve Udino
- School of Life and Environmental Sciences, Deakin University, Waurn Ponds, Victoria 3288, Australia
| | - Julia M. George
- Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA
| | - Matthew McKenzie
- School of Life and Environmental Sciences, Deakin University, Waurn Ponds, Victoria 3288, Australia
| | - Anaïs Pessato
- School of Life and Environmental Sciences, Deakin University, Waurn Ponds, Victoria 3288, Australia
| | - Ondi L. Crino
- School of Life and Environmental Sciences, Deakin University, Waurn Ponds, Victoria 3288, Australia
| | - Katherine L. Buchanan
- School of Life and Environmental Sciences, Deakin University, Waurn Ponds, Victoria 3288, Australia
| | - Mylene M. Mariette
- School of Life and Environmental Sciences, Deakin University, Waurn Ponds, Victoria 3288, Australia
- Estación Biológica de Doñana EBD-CSIC, Seville, 41092, Spain
| |
Collapse
|
7
|
Jørgensen LB, Overgaard J, Hunter-Manseau F, Pichaud N. Dramatic changes in mitochondrial substrate use at critically high temperatures: a comparative study using Drosophila. J Exp Biol 2021; 224:jeb.240960. [PMID: 33563650 DOI: 10.1242/jeb.240960] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 01/21/2021] [Indexed: 12/17/2022]
Abstract
Ectotherm thermal tolerance is critical to species distribution, but at present the physiological underpinnings of heat tolerance remain poorly understood. Mitochondrial function is perturbed at critically high temperatures in some ectotherms, including insects, suggesting that heat tolerance of these animals is linked to failure of oxidative phosphorylation (OXPHOS) and/or ATP production. To test this hypothesis, we measured mitochondrial oxygen consumption rate in six Drosophila species with different heat tolerance using high-resolution respirometry. Using a substrate-uncoupler-inhibitor titration protocol, we examined specific steps of the electron transport system to study how temperatures below, bracketing and above organismal heat limits affect mitochondrial function and substrate oxidation. At benign temperatures (19 and 30°C), complex I-supported respiration (CI-OXPHOS) was the most significant contributor to maximal OXPHOS. At higher temperatures (34, 38, 42 and 46°C), CI-OXPHOS decreased considerably, ultimately to very low levels at 42 and 46°C. The enzymatic catalytic capacity of complex I was intact across all temperatures and accordingly the decreased CI-OXPHOS is unlikely to be caused directly by hyperthermic denaturation/inactivation of complex I. Despite the reduction in CI-OXPHOS, maximal OXPHOS capacity was maintained in all species, through oxidation of alternative substrates - proline, succinate and, particularly, glycerol-3-phosphate - suggesting important mitochondrial flexibility at temperatures exceeding the organismal heat limit. Interestingly, this failure of CI-OXPHOS and compensatory oxidation of alternative substrates occurred at temperatures that correlated with species heat tolerance, such that heat-tolerant species could defend 'normal' mitochondrial function at higher temperatures than sensitive species. Future studies should investigate why CI-OXPHOS is perturbed and how this potentially affects ATP production rates.
Collapse
Affiliation(s)
| | - Johannes Overgaard
- Zoophysiology, Department of Biology, Aarhus University, 8000 Aarhus C, Denmark
| | - Florence Hunter-Manseau
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, Canada, E1A 3E9
| | - Nicolas Pichaud
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, Canada, E1A 3E9
| |
Collapse
|
8
|
Koch RE, Buchanan KL, Casagrande S, Crino O, Dowling DK, Hill GE, Hood WR, McKenzie M, Mariette MM, Noble DWA, Pavlova A, Seebacher F, Sunnucks P, Udino E, White CR, Salin K, Stier A. Integrating Mitochondrial Aerobic Metabolism into Ecology and Evolution. Trends Ecol Evol 2021; 36:321-332. [PMID: 33436278 DOI: 10.1016/j.tree.2020.12.006] [Citation(s) in RCA: 71] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 12/09/2020] [Accepted: 12/11/2020] [Indexed: 12/17/2022]
Abstract
Biologists have long appreciated the critical role that energy turnover plays in understanding variation in performance and fitness among individuals. Whole-organism metabolic studies have provided key insights into fundamental ecological and evolutionary processes. However, constraints operating at subcellular levels, such as those operating within the mitochondria, can also play important roles in optimizing metabolism over different energetic demands and time scales. Herein, we explore how mitochondrial aerobic metabolism influences different aspects of organismal performance, such as through changing adenosine triphosphate (ATP) and reactive oxygen species (ROS) production. We consider how such insights have advanced our understanding of the mechanisms underpinning key ecological and evolutionary processes, from variation in life-history traits to adaptation to changing thermal conditions, and we highlight key areas for future research.
Collapse
Affiliation(s)
- Rebecca E Koch
- Monash University, School of Biological Sciences, Clayton, VIC, 3800, Australia.
| | - Katherine L Buchanan
- Deakin University, School of Life and Environmental Sciences, Waurn Ponds, VIC, 3228, Australia
| | - Stefania Casagrande
- Max Planck Institute for Ornithology, Evolutionary Physiology Group, Seewiesen, Eberhard-Gwinner-Str. Haus 5, 82319, Seewiesen, Germany
| | - Ondi Crino
- Deakin University, School of Life and Environmental Sciences, Waurn Ponds, VIC, 3228, Australia
| | - Damian K Dowling
- Monash University, School of Biological Sciences, Clayton, VIC, 3800, Australia
| | - Geoffrey E Hill
- Auburn University, Department of Biological Sciences, Auburn, AL, 36849, USA
| | - Wendy R Hood
- Auburn University, Department of Biological Sciences, Auburn, AL, 36849, USA
| | - Matthew McKenzie
- Deakin University, School of Life and Environmental Sciences, Waurn Ponds, VIC, 3228, Australia
| | - Mylene M Mariette
- Deakin University, School of Life and Environmental Sciences, Waurn Ponds, VIC, 3228, Australia
| | - Daniel W A Noble
- The Australian National University, Division of Ecology and Evolution, Research School of Biology, Canberra, ACT, 2600, Australia
| | - Alexandra Pavlova
- Monash University, School of Biological Sciences, Clayton, VIC, 3800, Australia
| | - Frank Seebacher
- University of Sydney, School of Life and Environmental Sciences, Sydney, NSW, 2006, Australia
| | - Paul Sunnucks
- Monash University, School of Biological Sciences, Clayton, VIC, 3800, Australia
| | - Eve Udino
- Deakin University, School of Life and Environmental Sciences, Waurn Ponds, VIC, 3228, Australia
| | - Craig R White
- Monash University, School of Biological Sciences, Clayton, VIC, 3800, Australia
| | - Karine Salin
- Université de Brest, Ifremer, CNRS, IRD, Laboratory of Environmental Marine Sciences, Plouzané, 29280, France
| | - Antoine Stier
- University of Turku, Department of Biology, Turku, Finland; University of Glasgow, Institute of Biodiversity, Animal Health and Comparative Medicine, Glasgow, UK
| |
Collapse
|
9
|
Milani L, Ghiselli F. Faraway, so close. The comparative method and the potential of non-model animals in mitochondrial research. Philos Trans R Soc Lond B Biol Sci 2019; 375:20190186. [PMID: 31787048 DOI: 10.1098/rstb.2019.0186] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Inference from model organisms has been the engine for many discoveries in life science, but indiscriminate generalization leads to oversimplifications and misconceptions. Model organisms and inductive reasoning are irreplaceable: there is no other way to tackle the complexity of living systems. At the same time, it is not advisable to infer general patterns from a restricted number of species, which are very far from being representative of the diversity of life. Not all models are equal. Some organisms are suitable to find similarities across species, other highly specialized organisms can be used to focus on differences. In this opinion piece, we discuss the dominance of the mechanistic/reductionist approach in life sciences and make a case for an enhanced application of the comparative approach to study processes in all their various forms across different organisms. We also enlist some rising animal models in mitochondrial research, to exemplify how non-model organisms can be chosen in a comparative framework. These taxa often do not possess implemented tools and dedicated methods/resources. However, because of specific features, they have the potential to address still unanswered biological questions. Finally, we discuss future perspectives and caveats of the comparative method in the age of 'big data'. This article is part of the theme issue 'Linking the mitochondrial genotype to phenotype: a complex endeavour'.
Collapse
Affiliation(s)
- Liliana Milani
- Department of Biological, Geological, and Environmental Sciences, University of Bologna, Bologna, Italy
| | - Fabrizio Ghiselli
- Department of Biological, Geological, and Environmental Sciences, University of Bologna, Bologna, Italy
| |
Collapse
|
10
|
Ghiselli F, Milani L. Linking the mitochondrial genotype to phenotype: a complex endeavour. Philos Trans R Soc Lond B Biol Sci 2019; 375:20190169. [PMID: 31787041 DOI: 10.1098/rstb.2019.0169] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Finding causal links between genotype and phenotype is a major issue in biology, even more in mitochondrial biology. First of all, mitochondria form complex networks, undergoing fission and fusion and we do not know how such dynamics influence the distribution of mtDNA variants across the mitochondrial network and how they affect the phenotype. Second, the non-Mendelian inheritance of mitochondrial genes can have sex-specific effects and the mechanism of mitochondrial inheritance is still poorly understood, so it is not clear how selection and/or drift act on mtDNA genetic variation in each generation. Third, we still do not know how mtDNA expression is regulated; there is growing evidence for a convoluted mechanism that includes RNA editing, mRNA stability/turnover, post-transcriptional and post-translational modifications. Fourth, mitochondrial activity differs across species as a result of several interacting processes such as drift, adaptation, genotype-by-environment interactions, mitonuclear coevolution and epistasis. This issue will cover several aspects of mitochondrial biology along the path from genotype to phenotype, and it is subdivided into four sections focusing on mitochondrial genetic variation, on the relationship among mitochondria, germ line and sex, on the role of mitochondria in adaptation and phenotypic plasticity, and on some future perspectives in mitochondrial research. This article is part of the theme issue 'Linking the mitochondrial genotype to phenotype: a complex endeavour'.
Collapse
Affiliation(s)
- Fabrizio Ghiselli
- Department of Biological, Geological, and Environmental Sciences, University of Bologna, Bologna 40126, Italy
| | - Liliana Milani
- Department of Biological, Geological, and Environmental Sciences, University of Bologna, Bologna 40126, Italy
| |
Collapse
|