1
|
Morla J, Salin K, Lassus R, Favre-Marinet J, Sentis A, Daufresne M. Multigenerational exposure to temperature influences mitochondrial oxygen fluxes in the Medaka fish (Oryzias latipes). Acta Physiol (Oxf) 2024; 240:e14194. [PMID: 38924292 DOI: 10.1111/apha.14194] [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: 09/06/2023] [Revised: 05/08/2024] [Accepted: 06/18/2024] [Indexed: 06/28/2024]
Abstract
AIM Thermal sensitivity of cellular metabolism is crucial for animal physiology and survival under climate change. Despite recent efforts, effects of multigenerational exposure to temperature on the metabolic functioning remain poorly understood. We aimed at determining whether multigenerational exposure to temperature modulate the mitochondrial respiratory response of Medaka fish. METHODS We conducted a multigenerational exposure with Medaka fish reared multiple generations at 20 and 30°C (COLD and WARM fish, respectively). We then measured the oxygen consumption of tail muscle at two assay temperatures (20 and 30°C). Mitochondrial function was determined as the respiration supporting ATP synthesis (OXPHOS) and the respiration required to offset proton leak (LEAK(Omy)) in a full factorial design (COLD-20°C; COLD-30°C; WARM-20°C; WARM-30°C). RESULTS We found that higher OXPHOS and LEAK fluxes at 30°C compared to 20°C assay temperature. At each assay temperature, WARM fish had lower tissue oxygen fluxes than COLD fish. Interestingly, we did not find significant differences in respiratory flux when mitochondria were assessed at the rearing temperature of the fish (i.e., COLD-20°C vs. WARM -30°C). CONCLUSION The lower OXPHOS and LEAK capacities in warm fish are likely the result of the multigenerational exposure to warm temperature. This is consistent with a modulatory response of mitochondrial capacity to compensate for potential detrimental effects of warming on metabolism. Finally, the absence of significant differences in respiratory fluxes between COLD-20°C and WARM-30°C fish likely reflects an optimal respiration flux when organisms adapt to their thermal conditions.
Collapse
Affiliation(s)
- Julie Morla
- INRAE, Aix-Marseille University, UMR RECOVER, Aix-en-Provence, France
| | - Karine Salin
- Départment of Environment and Resources, IFREMER, Unité de Physiologie Fonctionnelle des Organismes Marins-LEMAR UMR 6530, BP70, Plouzané, France
| | - Rémy Lassus
- INRAE, Aix-Marseille University, UMR RECOVER, Aix-en-Provence, France
| | | | - Arnaud Sentis
- INRAE, Aix-Marseille University, UMR RECOVER, Aix-en-Provence, France
| | - Martin Daufresne
- INRAE, Aix-Marseille University, UMR RECOVER, Aix-en-Provence, France
| |
Collapse
|
2
|
Blanchard A, Aminot M, Gould N, Léger A, Pichaud N. Flies on the rise: acclimation effect on mitochondrial oxidation capacity at normal and high temperatures in Drosophila melanogaster. J Exp Biol 2024; 227:jeb247706. [PMID: 38841909 DOI: 10.1242/jeb.247706] [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: 03/07/2024] [Accepted: 05/28/2024] [Indexed: 06/07/2024]
Abstract
Increased average temperatures and extreme thermal events (such as heatwaves) brought forth by climate change impose important constraints on aerobic metabolism. Notably, mitochondrial metabolism, which is affected by both long- and short-term temperature changes, has been put forward as an important determinant for thermal tolerance of organisms. This study examined the influence of phenotypic plasticity on metabolic and physiological parameters in Drosophila melanogaster and the link between mitochondrial function and their upper thermal limits. We showed that D. melanogaster acclimated to 15°C have a 0.65°C lower critical thermal maximum (CTmax) compared with those acclimated to 24°C. Drosophila melanogaster acclimated to 15°C exhibited a higher proportion of shorter saturated and monounsaturated fatty acids, concomitant with lower proportions of polyunsaturated fatty acids. No mitochondrial quantitative changes (fractional area and number) were detected between acclimation groups, but changes of mitochondrial oxidation capacities were observed. Specifically, in both 15°C- and 24°C-acclimated flies, complex I-induced respiration was increased when measured between 15 and 24°C, but drastically declined when measured at 40°C. When succinate and glycerol-3-phosphate were added, this decrease was however compensated for in flies acclimated to 24°C, suggesting an important impact of acclimation on mitochondrial function related to thermal tolerance. Our study reveals that the use of oxidative substrates at high temperatures is influenced by acclimation temperature and strongly related to upper thermal tolerance as a difference of 0.65°C in CTmax translates into significant mitochondrial changes.
Collapse
Affiliation(s)
- Arianne Blanchard
- New Brunswick Centre for Precision Medicine, Moncton, NB E1C8X3, Canada
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB E1A 3E9, Canada
| | - Mélanie Aminot
- New Brunswick Centre for Precision Medicine, Moncton, NB E1C8X3, Canada
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB E1A 3E9, Canada
| | - Nathalie Gould
- New Brunswick Centre for Precision Medicine, Moncton, NB E1C8X3, Canada
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB E1A 3E9, Canada
| | - Adèle Léger
- New Brunswick Centre for Precision Medicine, Moncton, NB E1C8X3, Canada
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB E1A 3E9, Canada
| | - Nicolas Pichaud
- New Brunswick Centre for Precision Medicine, Moncton, NB E1C8X3, Canada
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB E1A 3E9, Canada
| |
Collapse
|
3
|
Léger A, Cormier SB, Blanchard A, Menail HA, Pichaud N. Investigating the thermal sensitivity of key enzymes involved in the energetic metabolism of three insect species. J Exp Biol 2024; 227:jeb247221. [PMID: 38680096 DOI: 10.1242/jeb.247221] [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: 12/19/2023] [Accepted: 04/16/2024] [Indexed: 05/01/2024]
Abstract
The metabolic responses of insects to high temperatures have been linked to their mitochondrial substrate oxidation capacity. However, the mechanism behind this mitochondrial flexibility is not well understood. Here, we used three insect species with different thermal tolerances (the honey bee, Apis mellifera; the fruit fly, Drosophila melanogaster; and the potato beetle, Leptinotarsa decemlineata) to characterize the thermal sensitivity of different metabolic enzymes. Specifically, we measured activity of enzymes involved in glycolysis (hexokinase, HK; pyruvate kinase, PK; and lactate dehydrogenase, LDH), pyruvate oxidation and the tricarboxylic acid cycle (pyruvate dehydrogenase, PDH; citrate synthase, CS; malate dehydrogenase, MDH; and aspartate aminotransferase, AAT), and the electron transport system (Complex I, CI; Complex II, CII; mitochondrial glycerol-3-phosphate dehydrogenase, mG3PDH; proline dehydrogenase, ProDH; and Complex IV, CIV), as well as that of ATP synthase (CV) at 18, 24, 30, 36, 42 and 45°C. Our results show that at high temperature, all three species have significantly increased activity of enzymes linked to FADH2 oxidation, specifically CII and mG3PDH. In fruit flies and honey bees, this coincides with a significant decrease of PDH and CS activity, respectively, that would limit NADH production. This is in line with the switch from NADH-linked substrates to FADH2-linked substrates previously observed with mitochondrial oxygen consumption. Thus, we demonstrate that even though the three insect species have a different metabolic regulation, a similar response to high temperature involving CII and mG3PDH is observed, denoting the importance of these proteins for thermal tolerance in insects.
Collapse
Affiliation(s)
- Adèle Léger
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, CanadaE1A 3E9
- New Brunswick Centre for Precision Medicine (NBCPM), Moncton, NB, CanadaE1C 8X3
| | - Simon B Cormier
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, CanadaE1A 3E9
- New Brunswick Centre for Precision Medicine (NBCPM), Moncton, NB, CanadaE1C 8X3
| | - Arianne Blanchard
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, CanadaE1A 3E9
- New Brunswick Centre for Precision Medicine (NBCPM), Moncton, NB, CanadaE1C 8X3
| | - Hichem A Menail
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, CanadaE1A 3E9
- New Brunswick Centre for Precision Medicine (NBCPM), Moncton, NB, CanadaE1C 8X3
| | - Nicolas Pichaud
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, CanadaE1A 3E9
- New Brunswick Centre for Precision Medicine (NBCPM), Moncton, NB, CanadaE1C 8X3
| |
Collapse
|
4
|
Pelletier D, Blier PU, Vézina F, Dufresne F, Paquin F, Christen F, Guillemette M. Under pressure-exploring partner changes, physiological responses and telomere dynamics in northern gannets across varying breeding conditions. PeerJ 2023; 11:e16457. [PMID: 38054014 PMCID: PMC10695113 DOI: 10.7717/peerj.16457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 10/23/2023] [Indexed: 12/07/2023] Open
Abstract
Background Life history theory predicts trade-offs between reproduction and survival in species like the northern gannet (Morus bassanus). During breeding, demanding foraging conditions lead them to expand their foraging range and diversify their diet, increasing the risk of reproductive failure. Changing partners may enhance breeding success but lead to more physiological costs. Methods To investigate the physiological costs of reproduction upon partner changes, we measured and compared 21 biomarkers related to telomere dynamics, oxidative stress, inflammation, hematology, nutritional status, and muscle damage. We used a longitudinal approach with gannets (n = 38) over three contrasting years (2017, 2018 and 2019). Results Our results suggest that annual breeding conditions exert a greater influence on physiological changes than partnership status. Individuals that changed partner experienced greater short-term stress than retained partners. This transient increase in stress was marked by short-term increases in oxidative lipid damage, lower antioxidant capacity, signs of inflammation, and greater weight loss than individuals that retained partners. During favorable conditions, individuals that changed mates had stabilized telomere length, decreased antioxidant capacity, glucose concentration, and muscle damage, along with increased oxygen transport capacity. Conversely, unfavorable breeding conditions led to increased telomere attrition, stabilized antioxidant capacity, decreased inflammation susceptibility, diminished oxygen transport capacity, and increased muscle damage. In the cases where partners were retained, distinct physiological changes were observed depending on the year's conditions, yet the telomere dynamics remained consistent across both partnership status categories. During the favorable year, there was an increase in unsaturated fatty acids and oxygen transport capacity in the blood, coupled with a reduction in inflammation potential and protein catabolism. In contrast, during the unfavorable year in the retained mates, we observed an increase in oxidative DNA damage, antioxidant capacity, weight loss, but a decrease in inflammation susceptibility as observed in changed mates. Discussion Our study shows that behavioral flexibility such as mate switching can help seabirds cope with the challenges of food scarcity during reproduction, but these coping strategies may have a negative impact on physiological status at the individual level. In addition, the marked reduction in telomere length observed during harsh conditions, coupled with the stabilization of telomere length in favorable conditions, highlights the long-term physiological impact of annual breeding conditions on seabirds. These findings underscore the effect on their potential survival and fitness, emphasizing that the influence of annual breeding conditions is greater than that of partnership status.
Collapse
Affiliation(s)
- David Pelletier
- Department of Biology, Université du Québec à Rimouski, Rimouski, Québec, Canada
- Department of Biology, Cégep de Rimouski, Rimouski, Québec, Canada
| | - Pierre U. Blier
- Department of Biology, Université du Québec à Rimouski, Rimouski, Québec, Canada
| | - François Vézina
- Department of Biology, Université du Québec à Rimouski, Rimouski, Québec, Canada
| | - France Dufresne
- Department of Biology, Université du Québec à Rimouski, Rimouski, Québec, Canada
| | - Frédérique Paquin
- Department of Biology, Université du Québec à Rimouski, Rimouski, Québec, Canada
| | - Felix Christen
- Department of Biology, Université du Québec à Rimouski, Rimouski, Québec, Canada
| | - Magella Guillemette
- Department of Biology, Université du Québec à Rimouski, Rimouski, Québec, Canada
| |
Collapse
|
5
|
Cominassi L, Ressel KN, Brooking AA, Marbacher P, Ransdell-Green EC, O'Brien KM. Metabolic rate increases with acclimation temperature and is associated with mitochondrial function in some tissues of threespine stickleback. J Exp Biol 2022; 225:jeb244659. [PMID: 36268761 PMCID: PMC9687547 DOI: 10.1242/jeb.244659] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 10/07/2022] [Indexed: 11/20/2022]
Abstract
The metabolic rate (ṀO2) of eurythermal fishes changes in response to temperature, yet it is unclear how changes in mitochondrial function contribute to changes in ṀO2. We hypothesized that ṀO2 would increase with acclimation temperature in the threespine stickleback (Gasterosteus aculeatus) in parallel with metabolic remodeling at the cellular level but that changes in metabolism in some tissues, such as liver, would contribute more to changes in ṀO2 than others. Threespine stickleback were acclimated to 5, 12 and 20°C for 7 to 21 weeks. At each temperature, standard and maximum metabolic rate (SMR and MMR, respectively), and absolute aerobic scope (AAS) were quantified, along with mitochondrial respiration rates in liver, oxidative skeletal and cardiac muscles, and the maximal activity of citrate synthase (CS) and lactate dehydrogenase (LDH) in liver, and oxidative and glycolytic skeletal muscles. SMR, MMR and AAS increased with acclimation temperature, along with rates of mitochondrial phosphorylating respiration in all tissues. Low SMR and MMR at 5°C were associated with low or undetectable rates of mitochondrial complex II activity and a greater reliance on complex I activity in liver, oxidative skeletal muscle and heart. SMR was positively correlated with cytochrome c oxidase (CCO) activity in liver and oxidative muscle, but not mitochondrial proton leak, whereas MMR was positively correlated with CCO activity in liver. Overall, the results suggest that changes in ṀO2 in response to temperature are driven by changes in some aspects of mitochondrial function in some, but not all, tissues of threespine stickleback.
Collapse
Affiliation(s)
- Louise Cominassi
- University of Alaska Fairbanks, Institute of Arctic Biology, PO Box 757000 Fairbanks, AK 99775, USA
| | - Kirsten N. Ressel
- University of Alaska Fairbanks, Institute of Arctic Biology, PO Box 757000 Fairbanks, AK 99775, USA
| | - Allison A. Brooking
- University of Alaska Fairbanks, Institute of Arctic Biology, PO Box 757000 Fairbanks, AK 99775, USA
| | - Patrick Marbacher
- University of Alaska Fairbanks, Institute of Arctic Biology, PO Box 757000 Fairbanks, AK 99775, USA
| | | | - Kristin M. O'Brien
- University of Alaska Fairbanks, Institute of Arctic Biology, PO Box 757000 Fairbanks, AK 99775, USA
| |
Collapse
|
6
|
Cormier SB, Léger A, Boudreau LH, Pichaud N. Overwintering in North American domesticated honeybees (Apis mellifera) causes mitochondrial reprogramming while enhancing cellular immunity. J Exp Biol 2022; 225:276355. [PMID: 35938391 DOI: 10.1242/jeb.244440] [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: 04/19/2022] [Accepted: 07/26/2022] [Indexed: 11/20/2022]
Abstract
Many factors negatively impact domesticated honeybee (Apis mellifera) health causing a global decrease in their population year after year with major losses occurring during winter, and the cause remains thus far unknown. Here, we monitored for 12 months North American colonies of honeybees enduring important temperature variations throughout the year, to assess the metabolism and immune system of honeybees of summer and winter individuals. Our results show that in flight muscle, mitochondrial respiration via complex I during winter is drastically reduced compared to summer. However, the capacity for succinate and glycerol-3-phosphate (G3P) oxidation by mitochondria is increased during winter, resulting in higher mitochondrial oxygen consumption when complex I substrates, succinate and G3P were assessed altogether. Pyruvate kinase, lactate dehydrogenase, aspartate aminotransferase, citrate synthase and malate dehydrogenase tend to have reduced activity levels in winter unlike hexokinase, NADH dehydrogenase and pyruvate dehydrogenase. Transcript abundance of highly important immunity proteins like Vitellogenin and Defensin-1 were also increased in winter bees, and a stronger phagocytic response as well as a better hemocyte viability was observed during winter. Thus, a reorganization of substrate utilization favoring succinate and G3P while negatively affecting complex I of the ETS is occurring during winter. We suggest that this might be due to complex I transitioning to a dormant conformation through post-translational modification. Winter bees also have an increased response for antibacterial elimination in honeybees. Overall, this study highlights previously unknown cellular mechanisms between summer and winter honeybees that further our knowledge about this important species.
Collapse
Affiliation(s)
- Simon B Cormier
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, E1A3E9, Canada.,New Brunswick Centre for Precision Medicine (NBCPM), Moncton, NB, E1C8X3, Canada
| | - Adèle Léger
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, E1A3E9, Canada.,New Brunswick Centre for Precision Medicine (NBCPM), Moncton, NB, E1C8X3, Canada
| | - Luc H Boudreau
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, E1A3E9, Canada.,New Brunswick Centre for Precision Medicine (NBCPM), Moncton, NB, E1C8X3, Canada
| | - Nicolas Pichaud
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, E1A3E9, Canada.,New Brunswick Centre for Precision Medicine (NBCPM), Moncton, NB, E1C8X3, Canada
| |
Collapse
|
7
|
Menail HA, Cormier SB, Ben Youssef M, Jørgensen LB, Vickruck JL, Morin P, Boudreau LH, Pichaud N. Flexible Thermal Sensitivity of Mitochondrial Oxygen Consumption and Substrate Oxidation in Flying Insect Species. Front Physiol 2022; 13:897174. [PMID: 35547573 PMCID: PMC9081799 DOI: 10.3389/fphys.2022.897174] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 04/06/2022] [Indexed: 12/26/2022] Open
Abstract
Mitochondria have been suggested to be paramount for temperature adaptation in insects. Considering the large range of environments colonized by this taxon, we hypothesized that species surviving large temperature changes would be those with the most flexible mitochondria. We thus investigated the responses of mitochondrial oxidative phosphorylation (OXPHOS) to temperature in three flying insects: the honeybee (Apis mellifera carnica), the fruit fly (Drosophila melanogaster) and the Colorado potato beetle (Leptinotarsa decemlineata). Specifically, we measured oxygen consumption in permeabilized flight muscles of these species at 6, 12, 18, 24, 30, 36, 42 and 45°C, sequentially using complex I substrates, proline, succinate, and glycerol-3-phosphate (G3P). Complex I respiration rates (CI-OXPHOS) were very sensitive to temperature in honeybees and fruit flies with high oxygen consumption at mid-range temperatures but a sharp decline at high temperatures. Proline oxidation triggers a major increase in respiration only in potato beetles, following the same pattern as CI-OXPHOS for honeybees and fruit flies. Moreover, both succinate and G3P oxidation allowed an important increase in respiration at high temperatures in honeybees and fruit flies (and to a lesser extent in potato beetles). However, when reaching 45°C, this G3P-induced respiration rate dropped dramatically in fruit flies. These results demonstrate that mitochondrial functions are more resilient to high temperatures in honeybees compared to fruit flies. They also indicate an important but species-specific mitochondrial flexibility for substrate oxidation to sustain high oxygen consumption levels at high temperatures and suggest previously unknown adaptive mechanisms of flying insects’ mitochondria to temperature.
Collapse
Affiliation(s)
- Hichem A Menail
- New Brunswick Centre for Precision Medicine, Moncton, NB, Canada.,Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, Canada
| | - Simon B Cormier
- New Brunswick Centre for Precision Medicine, Moncton, NB, Canada.,Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, Canada
| | - Mariem Ben Youssef
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, Canada
| | | | - Jess L Vickruck
- Fredericton Research and Development Centre, Agriculture and Agri-Food Canada, Fredericton, NB, Canada
| | - Pier Morin
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, Canada
| | - Luc H Boudreau
- New Brunswick Centre for Precision Medicine, Moncton, NB, Canada.,Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, Canada
| | - Nicolas Pichaud
- New Brunswick Centre for Precision Medicine, Moncton, NB, Canada.,Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, Canada
| |
Collapse
|
8
|
Ressel KN, Cominassi L, Sarrimanolis J, O’Brien KM. Aerobic scope is not maintained at low temperature and is associated with cardiac aerobic capacity in the three-spined stickleback Gasterosteus aculeatus. JOURNAL OF FISH BIOLOGY 2022; 100:444-453. [PMID: 34816430 PMCID: PMC8881366 DOI: 10.1111/jfb.14955] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 10/17/2021] [Accepted: 11/19/2021] [Indexed: 06/13/2023]
Abstract
Metabolic thermal plasticity is central to the survival of fishes in a changing environment. The eurythermal three-spined stickleback Gasterosteus aculeatus displays thermal plasticity at the cellular level with an increase in the activity of key metabolic enzymes in response to cold acclimation. Nonetheless, it is unknown if these changes are sufficient to completely compensate for the depressive effects of cold temperature on whole organismal metabolic rate (ṀO2 ). The authors hypothesized that as a cold-tolerant, eurythermal fish, absolute aerobic scope (AAS), the difference between the maximum metabolic rate (MMR) and standard metabolic rate (SMR), would be maintained in G. aculeatus following acclimation to a range of temperatures that span its habitat temperatures. To test this hypothesis, G. aculeatus were acclimated to 5, 12 and 20°C for 20-32 weeks, and SMR, MMR and aerobic scope (AS) were quantified at each acclimation temperature. The maximal activity of citrate synthase (CS), a marker enzyme of aerobic metabolism, was also quantified in heart ventricles to determine if cardiac aerobic capacity is associated with AS at these temperatures. SMR increased with acclimation temperature and was significantly different among all three temperature groups. MMR was similar between animals at 5 and 12°C and between animals at 12 and 20°C but was 2.6-fold lower in fish at 5°C compared with those at 20°C, resulting in a lower AAS in fish at 5°C compared with those at 12 and 20°C. Correlated with a higher AAS in animals acclimated to 12 and 20°C was a larger relative ventricular mass and higher CS activity per 100 g body mass compared with animals at 5°C. Together, the results indicate that despite their eurythermal nature, AS is not maintained at low temperature but is associated with cardiac aerobic metabolic capacity.
Collapse
Affiliation(s)
- Kirsten N. Ressel
- University of Alaska, Fairbanks, Institute of Arctic Biology, Fairbanks, Alaska, U.S.A
| | - Louise Cominassi
- University of Alaska, Fairbanks, Institute of Arctic Biology, Fairbanks, Alaska, U.S.A
| | - Jon Sarrimanolis
- University of Alaska, Fairbanks, Institute of Arctic Biology, Fairbanks, Alaska, U.S.A
| | - Kristin M. O’Brien
- University of Alaska, Fairbanks, Institute of Arctic Biology, Fairbanks, Alaska, U.S.A
| |
Collapse
|
9
|
Erić P, Patenković A, Erić K, Tanasković M, Davidović S, Rakić M, Savić Veselinović M, Stamenković-Radak M, Jelić M. Temperature-Specific and Sex-Specific Fitness Effects of Sympatric Mitochondrial and Mito-Nuclear Variation in Drosophila obscura. INSECTS 2022; 13:insects13020139. [PMID: 35206713 PMCID: PMC8880146 DOI: 10.3390/insects13020139] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 01/20/2022] [Accepted: 01/22/2022] [Indexed: 12/28/2022]
Abstract
Simple Summary Does variation in the mitochondrial DNA sequence influence the survival and reproduction of an individual? What is the purpose of genetic variation of the mitochondrial DNA between individuals from the same population? As a simple laboratory model, Drosophila species can give us the answer to this question. Creating experimental lines with different combinations of mitochondrial and nuclear genomic DNA and testing how successful these lines were in surviving in different experimental set-ups enables us to deduce the effect that both genomes have on fitness. This study on D. obscura experimentally validates theoretical models that explain the persistence of mitochondrial DNA variation within populations. Our results shed light on the various mechanisms that maintain this type of variation. Finally, by conducting the experiments on two experimental temperatures, we have shown that environmental variations can support mitochondrial DNA variation within populations. Abstract The adaptive significance of sympatric mitochondrial (mtDNA) variation and the role of selective mechanisms that maintain it are debated to this day. Isofemale lines of Drosophila obscura collected from four populations were backcrossed within populations to construct experimental lines, with all combinations of mtDNA Cyt b haplotypes and nuclear genetic backgrounds (nuDNA). Individuals of both sexes from these lines were then subjected to four fitness assays (desiccation resistance, developmental time, egg-to-adult viability and sex ratio) on two experimental temperatures to examine the role of temperature fluctuations and sex-specific selection, as well as the part that interactions between the two genomes play in shaping mtDNA variation. The results varied across populations and fitness components. In the majority of comparisons, they show that sympatric mitochondrial variants affect fitness. However, their effect should be examined in light of interactions with nuDNA, as mito-nuclear genotype was even more influential on fitness across all components. We found both sex-specific and temperature-specific differences in mitochondrial and mito-nuclear genotype ranks in all fitness components. The effect of temperature-specific selection was found to be more prominent, especially in desiccation resistance. From the results of different components tested, we can also infer that temperature-specific mito-nuclear interactions rather than sex-specific selection on mito-nuclear genotypes have a more substantial role in preserving mtDNA variation in this model species.
Collapse
Affiliation(s)
- Pavle Erić
- Department of Genetics of Populations and Ecogenotoxicology, Institute for Biological Research “Siniša Stanković”–National Institute of the Republic of Serbia, University of Belgrade, Bulevar Despota Stefana 142, 11060 Belgrade, Serbia; (A.P.); (K.E.); (M.T.); (S.D.); (M.R.)
- Correspondence: ; Tel.: +381-112-078-334
| | - Aleksandra Patenković
- Department of Genetics of Populations and Ecogenotoxicology, Institute for Biological Research “Siniša Stanković”–National Institute of the Republic of Serbia, University of Belgrade, Bulevar Despota Stefana 142, 11060 Belgrade, Serbia; (A.P.); (K.E.); (M.T.); (S.D.); (M.R.)
| | - Katarina Erić
- Department of Genetics of Populations and Ecogenotoxicology, Institute for Biological Research “Siniša Stanković”–National Institute of the Republic of Serbia, University of Belgrade, Bulevar Despota Stefana 142, 11060 Belgrade, Serbia; (A.P.); (K.E.); (M.T.); (S.D.); (M.R.)
| | - Marija Tanasković
- Department of Genetics of Populations and Ecogenotoxicology, Institute for Biological Research “Siniša Stanković”–National Institute of the Republic of Serbia, University of Belgrade, Bulevar Despota Stefana 142, 11060 Belgrade, Serbia; (A.P.); (K.E.); (M.T.); (S.D.); (M.R.)
| | - Slobodan Davidović
- Department of Genetics of Populations and Ecogenotoxicology, Institute for Biological Research “Siniša Stanković”–National Institute of the Republic of Serbia, University of Belgrade, Bulevar Despota Stefana 142, 11060 Belgrade, Serbia; (A.P.); (K.E.); (M.T.); (S.D.); (M.R.)
| | - Mina Rakić
- Department of Genetics of Populations and Ecogenotoxicology, Institute for Biological Research “Siniša Stanković”–National Institute of the Republic of Serbia, University of Belgrade, Bulevar Despota Stefana 142, 11060 Belgrade, Serbia; (A.P.); (K.E.); (M.T.); (S.D.); (M.R.)
- Faculty of Biology, University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia; (M.S.V.); (M.S.-R.); (M.J.)
| | - Marija Savić Veselinović
- Faculty of Biology, University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia; (M.S.V.); (M.S.-R.); (M.J.)
| | - Marina Stamenković-Radak
- Faculty of Biology, University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia; (M.S.V.); (M.S.-R.); (M.J.)
| | - Mihailo Jelić
- Faculty of Biology, University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia; (M.S.V.); (M.S.-R.); (M.J.)
| |
Collapse
|
10
|
Michaelsen J, Fago A, Bundgaard A. High temperature impairs mitochondrial function in rainbow trout cardiac mitochondria. J Exp Biol 2021; 224:jeb.242382. [DOI: 10.1242/jeb.242382] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 03/18/2021] [Indexed: 12/17/2022]
Abstract
ABSTRACT
Mitochondria provide cellular energy through oxidative phosphorylation, and thus temperature-induced constraints on mitochondrial function may be crucial to animal aerobic scope and thermal tolerance. Here, we report the effect of temperature in the range 5–30°C on respiration rates of isolated cardiac mitochondria from rainbow trout (Oncorhynchus mykiss) studied by high-resolution respirometry and spectrophotometric enzyme activity assays. Arrhenius breakpoint temperature analysis indicated that mitochondrial respiration rates under phosphorylating and fully uncoupled conditions increased exponentially up to 20°C, but stopped increasing at higher temperatures. In contrast, respiration rates measured under non-phosphorylating leak conditions continued to increase up to 30°C. The decrease in the ratio between phosphorylating and uncoupled respiration at high temperature indicated that phosphorylation was gradually impaired with increasing temperature, possibly because of the steadily increasing proton leak across the membrane. In addition, we found that complex I (NADH dehydrogenase) activity decreased above 20°C, similarly to mitochondrial respiration, and that complex I was unstable in the presence of detergents, suggesting that it may be particularly sensitive to changes in its interaction with membrane phospholipids. In contrast, complex II (succinate dehydrogenase) maintained activity at temperatures above 20°C, although succinate oxidation was insufficient to compensate for the loss of complex I activity in intact mitochondria. Together, these results indicate that the temperature-induced decrease in cardiac mitochondrial function coincides with the temperature at which trout aerobic scope peaks, and is largely due to impaired phosphorylation and complex I activity.
Collapse
Affiliation(s)
- Jakob Michaelsen
- Department of Biology, Aarhus University, 8000 Aarhus C, Denmark
| | - Angela Fago
- Department of Biology, Aarhus University, 8000 Aarhus C, Denmark
| | - Amanda Bundgaard
- Department of Biology, Aarhus University, 8000 Aarhus C, Denmark
| |
Collapse
|
11
|
Martin KE, Currie S, Pichaud N. Mitochondrial physiology and responses to elevated hydrogen sulphide in two isogenic lineages of an amphibious mangrove fish. J Exp Biol 2021; 224:jeb.241216. [PMID: 33688059 DOI: 10.1242/jeb.241216] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 03/01/2021] [Indexed: 12/14/2022]
Abstract
Hydrogen sulphide (H2S) is toxic and can act as a selective pressure on aquatic organisms, facilitating a wide range of adaptations for life in sulphidic environments. Mangrove rivulus (Kryptolebias marmoratus) inhabit mangrove swamps and have developed high tolerance to environmental H2S. They are hermaphroditic and can self-fertilize, producing distinct isogenic lineages with different sensitivity to H2S. Here, we tested the hypothesis that observed differences in responses to H2S are the result of differences in mitochondrial functions. For this purpose, we performed two experimental series, testing (1) the overall mitochondrial oxidizing capacities and (2) the kinetics of apparent H2S mitochondrial oxidation and inhibition in two distinct lineages of mangrove rivulus, originally collected from Belize and Honduras. We used permeabilized livers from both lineages, measured mitochondrial oxidation, and monitored changes during gradual increases of sulphide. Ultimately, we determined that each lineage has a distinct strategy for coping with elevated H2S, indicating divergences in mitochondrial function and metabolism. The Honduras lineage has higher anaerobic capacity substantiated by higher lactate dehydrogenase activity and higher apparent H2S oxidation rates, likely enabling them to tolerate H2S by escaping aquatic H2S in a terrestrial environment. However, Belize fish have increased cytochrome c oxidase and citrate synthase activities as well as increased succinate contribution to mitochondrial respiration, allowing them to tolerate higher levels of aquatic H2S without inhibition of mitochondrial oxygen consumption. Our study reveals distinct physiological strategies in genetic lineages of a single species, indicating possible genetic and/or functional adaptations to sulphidic environments at the mitochondrial level.
Collapse
Affiliation(s)
- Keri E Martin
- Department of Biology, Mount Allison University, Sackville, NB, Canada, E4L 1E4
| | - Suzanne Currie
- Department of Biology, Acadia University, Wolfville, NS, Canada, B4P 2R6
| | - Nicolas Pichaud
- Department of Chemistry and Biochemistry, University of Moncton, Moncton, NB, Canada, E1A 3E9
| |
Collapse
|
12
|
Ekström A, Sundell E, Morgenroth D, McArley T, Gårdmark A, Huss M, Sandblom E. Cardiorespiratory adjustments to chronic environmental warming improve hypoxia tolerance in European perch ( Perca fluviatilis). J Exp Biol 2021; 224:jeb.241554. [PMID: 33568442 DOI: 10.1242/jeb.241554] [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: 12/02/2020] [Accepted: 02/01/2021] [Indexed: 11/20/2022]
Abstract
Aquatic hypoxia will become increasingly prevalent in the future as a result of eutrophication combined with climate warming. While short-term warming typically constrains fish hypoxia tolerance, many fishes cope with warming by adjusting physiological traits through thermal acclimation. Yet, little is known about how such adjustments affect tolerance to hypoxia. We examined European perch (Perca fluviatilis) from the Biotest enclosure (23°C, Biotest population), a unique ∼1 km2 ecosystem artificially warmed by cooling water from a nuclear power plant, and an adjacent reference site (16-18°C, reference population). Specifically, we evaluated how acute and chronic warming affect routine oxygen consumption rate (Ṁ O2,routine) and cardiovascular performance in acute hypoxia, alongside assessment of the thermal acclimation of the aerobic contribution to hypoxia tolerance (critical O2 tension for Ṁ O2,routine: P crit) and absolute hypoxia tolerance (O2 tension at loss of equilibrium; P LOE). Chronic adjustments (possibly across lifetime or generations) alleviated energetic costs of warming in Biotest perch by depressing Ṁ O2,routine and cardiac output, and by increasing blood O2 carrying capacity relative to reference perch acutely warmed to 23°C. These adjustments were associated with improved maintenance of cardiovascular function and Ṁ O2,routine in hypoxia (i.e. reduced P crit). However, while P crit was only partially thermally compensated in Biotest perch, they had superior absolute hypoxia tolerance (i.e. lowest P LOE) relative to reference perch irrespective of temperature. We show that European perch can thermally adjust physiological traits to safeguard and even improve hypoxia tolerance during chronic environmental warming. This points to cautious optimism that eurythermal fish species may be resilient to the imposition of impaired hypoxia tolerance with climate warming.
Collapse
Affiliation(s)
- Andreas Ekström
- Department of Biological and Environmental Sciences, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Erika Sundell
- Department of Biological and Environmental Sciences, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Daniel Morgenroth
- Department of Biological and Environmental Sciences, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Tristan McArley
- Department of Biological and Environmental Sciences, University of Gothenburg, 405 30 Gothenburg, Sweden
| | - Anna Gårdmark
- Department of Aquatic Resources, Swedish University of Agricultural Sciences, 742 42 Öregrund, Sweden
| | - Magnus Huss
- Department of Aquatic Resources, Swedish University of Agricultural Sciences, 742 42 Öregrund, Sweden
| | - Erik Sandblom
- Department of Biological and Environmental Sciences, University of Gothenburg, 405 30 Gothenburg, Sweden
| |
Collapse
|
13
|
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
|
14
|
Gerber L, Clow KA, Gamperl AK. Acclimation to warm temperatures has important implications for mitochondrial function in Atlantic salmon ( Salmo salar). J Exp Biol 2021; 224:jeb236257. [PMID: 33288533 DOI: 10.1242/jeb.236257] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Accepted: 12/01/2020] [Indexed: 12/16/2022]
Abstract
In fish, the capacity of thermal acclimation to preserve cardiac mitochondrial function under future warming scenarios is important to understand given the central roles that cardiac energy metabolism and performance play in this taxa's thermal tolerance. We acclimated Atlantic salmon to 12 and 20°C (for >2 months), and investigated the effects of acute and chronic warming on cardiac mitochondrial respiration and reactive oxygen species (ROS) production (release rate) using high-resolution fluorespirometry. Further, we compared the sensitivity of mitochondrial respiration to nitric oxide (i.e. the NO IC50), and assessed the mitochondrial response to anoxia-reoxygenation (AR). Acute exposure to 20°C increased maximal mitochondrial respiration by ∼55%; however, the mitochondria's complex I respiratory control ratio was 17% lower and ROS production was increased by ≥60%. Acclimation to 20°C: (1) preserved mitochondrial coupling and aerobic capacity; (2) decreased the mitochondria's ROS production by ∼30%; (3) increased the mitochondria's NO IC50 by ∼23%; and (4) improved mitochondrial membrane integrity at 20°C. AR did not affect mitochondrial function at 12°C, but acute exposure to 20°C and AR depressed maximal mitochondrial respiration (by ∼9%) and coupling (by ∼16%) without impacting ROS production. Finally, warm acclimation did not improve the capacity of mitochondria to recover from AR, indicating that there was no 'cross-tolerance' between these challenges. Our findings provide compelling evidence that thermal plasticity of cardiac mitochondrial function contributes to the Atlantic salmon's capability to survive at ≥20°C for prolonged periods, but call into question whether this plasticity may allow them to withstand high temperatures when combined with other stressors.
Collapse
Affiliation(s)
- Lucie Gerber
- Department of Ocean Sciences, Memorial University, St. John's, NL A1C 5S7, Canada
| | - Kathy A Clow
- Department of Ocean Sciences, Memorial University, St. John's, NL A1C 5S7, Canada
| | - Anthony K Gamperl
- Department of Ocean Sciences, Memorial University, St. John's, NL A1C 5S7, Canada
| |
Collapse
|
15
|
Gerber L, Clow KA, Mark FC, Gamperl AK. Improved mitochondrial function in salmon (Salmo salar) following high temperature acclimation suggests that there are cracks in the proverbial 'ceiling'. Sci Rep 2020; 10:21636. [PMID: 33303856 PMCID: PMC7729908 DOI: 10.1038/s41598-020-78519-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 11/22/2020] [Indexed: 11/09/2022] Open
Abstract
Mitochondrial function can provide key insights into how fish will respond to climate change, due to its important role in heart performance, energy metabolism and oxidative stress. However, whether warm acclimation can maintain or improve the energetic status of the fish heart when exposed to short-term heat stress is not well understood. We acclimated Atlantic salmon, a highly aerobic eurythermal species, to 12 and 20 °C, then measured cardiac mitochondrial functionality and integrity at 20 °C and at 24, 26 and 28 °C (this species' critical thermal maximum ± 2 °C). Acclimation to 20 °C vs. 12 °C enhanced many aspects of mitochondrial respiratory capacity and efficiency up to 24 °C, and preserved outer mitochondrial membrane integrity up to 26 °C. Further, reactive oxygen species (ROS) production was dramatically decreased at all temperatures. These data suggest that salmon acclimated to 'normal' maximum summer temperatures are capable of surviving all but the most extreme ocean heat waves, and that there is no 'tradeoff' in heart mitochondrial function when Atlantic salmon are acclimated to high temperatures (i.e., increased oxidative phosphorylation does not result in heightened ROS production). This study suggests that fish species may show quite different acclimatory responses when exposed to prolonged high temperatures, and thus, susceptibility to climate warming.
Collapse
Affiliation(s)
- Lucie Gerber
- Department of Ocean Sciences, Memorial University, St. John's, NL, Canada.
| | - Kathy A Clow
- Department of Ocean Sciences, Memorial University, St. John's, NL, Canada
| | - Felix C Mark
- Section Integrative Ecophysiology, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Anthony K Gamperl
- Department of Ocean Sciences, Memorial University, St. John's, NL, Canada
| |
Collapse
|
16
|
Pichaud N, Ekström A, Breton S, Sundström F, Rowinski P, Blier PU, Sandblom E. Adjustments of cardiac mitochondrial phenotype in a warmer thermal habitat is associated with oxidative stress in European perch, Perca fluviatilis. Sci Rep 2020; 10:17697. [PMID: 33077851 PMCID: PMC7572411 DOI: 10.1038/s41598-020-74788-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 09/18/2020] [Indexed: 12/18/2022] Open
Abstract
Mitochondria are playing key roles in setting the thermal limits of fish, but how these organelles participate in selection mechanisms during extreme thermal events associated with climate warming in natural populations is unclear. Here, we investigated the thermal effects on mitochondrial metabolism, oxidative stress, and mitochondrial gene expression in cardiac tissues of European perch (Perca fluviatilis) collected from an artificially heated ecosystem, the "Biotest enclosure", and an adjacent reference area in the Baltic sea with normal temperatures (~ 23 °C and ~ 16 °C, respectively, at the time of capture in summer). Fish were sampled one month after a heat wave that caused the Biotest temperatures to peak at ~ 31.5 °C, causing significant mortality. When assayed at 23 °C, Biotest perch maintained high mitochondrial capacities, while reference perch displayed depressed mitochondrial functions relative to measurements at 16 °C. Moreover, mitochondrial gene expression of nd4 (mitochondrial subunit of complex I) was higher in Biotest fish, likely explaining the increased respiration rates observed in this population. Nonetheless, cardiac tissue from Biotest perch displayed higher levels of oxidative damage, which may have resulted from their chronically warm habitat, as well as the extreme temperatures encountered during the preceding summer heat wave. We conclude that eurythermal fish such as perch are able to adjust and maintain mitochondrial capacities of highly aerobic organs such as the heart when exposed to a warming environment as predicted with climate change. However, this might come at the expense of exacerbated oxidative stress, potentially threatening performance in nature.
Collapse
Affiliation(s)
- Nicolas Pichaud
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, E1A 3E9, Canada. .,Department of Biological and Environmental Sciences, University of Gothenburg, 405 30, Gothenburg, Sweden. .,Department of Biology, Université du Québec à Rimouski, Rimouski, QC, G5L 3A1, Canada.
| | - Andreas Ekström
- Department of Biological and Environmental Sciences, University of Gothenburg, 405 30, Gothenburg, Sweden
| | - Sophie Breton
- Department of Biological Sciences, Université de Montréal, Montréal, QC, H2V 2S9, Canada
| | - Fredrik Sundström
- Department of Ecology and Genetics, Uppsala University, 752 36, Uppsala, Sweden
| | - Piotr Rowinski
- Department of Ecology and Genetics, Uppsala University, 752 36, Uppsala, Sweden
| | - Pierre U Blier
- Department of Biology, Université du Québec à Rimouski, Rimouski, QC, G5L 3A1, Canada
| | - Erik Sandblom
- Department of Biological and Environmental Sciences, University of Gothenburg, 405 30, Gothenburg, Sweden
| |
Collapse
|
17
|
Immonen E, Berger D, Sayadi A, Liljestrand‐Rönn J, Arnqvist G. An experimental test of temperature-dependent selection on mitochondrial haplotypes in Callosobruchus maculatus seed beetles. Ecol Evol 2020; 10:11387-11398. [PMID: 33144972 PMCID: PMC7593184 DOI: 10.1002/ece3.6775] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/11/2020] [Accepted: 08/12/2020] [Indexed: 01/05/2023] Open
Abstract
Mitochondrial DNA (mtDNA) consists of few but vital maternally inherited genes that interact closely with nuclear genes to produce cellular energy. How important mtDNA polymorphism is for adaptation is still unclear. The assumption in population genetic studies is often that segregating mtDNA variation is selectively neutral. This contrasts with empirical observations of mtDNA haplotypes affecting fitness-related traits and thermal sensitivity, and latitudinal clines in mtDNA haplotype frequencies. Here, we experimentally test whether ambient temperature affects selection on mtDNA variation, and whether such thermal effects are influenced by intergenomic epistasis due to interactions between mitochondrial and nuclear genes, using replicated experimental evolution in Callosobruchus maculatus seed beetle populations seeded with a mixture of different mtDNA haplotypes. We also test for sex-specific consequences of mtDNA evolution on reproductive success, given that mtDNA mutations can have sexually antagonistic fitness effects. Our results demonstrate natural selection on mtDNA haplotypes, with some support for thermal environment influencing mtDNA evolution through mitonuclear epistasis. The changes in male and female reproductive fitness were both aligned with changes in mtDNA haplotype frequencies, suggesting that natural selection on mtDNA is sexually concordant in stressful thermal environments. We discuss the implications of our findings for the evolution of mtDNA.
Collapse
Affiliation(s)
- Elina Immonen
- Department of Ecology and Evolution/Evolutionary BiologyUppsala UniversityUppsalaSweden
| | - David Berger
- Department of Ecology and Evolution/Animal EcologyUppsala UniversityUppsalaSweden
| | - Ahmed Sayadi
- Department of Ecology and Evolution/Animal EcologyUppsala UniversityUppsalaSweden
| | | | - Göran Arnqvist
- Department of Ecology and Evolution/Animal EcologyUppsala UniversityUppsalaSweden
| |
Collapse
|
18
|
Simard C, Lebel A, Allain EP, Touaibia M, Hebert-Chatelain E, Pichaud N. Metabolic Characterization and Consequences of Mitochondrial Pyruvate Carrier Deficiency in Drosophila melanogaster. Metabolites 2020; 10:metabo10090363. [PMID: 32899962 PMCID: PMC7570025 DOI: 10.3390/metabo10090363] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 08/24/2020] [Accepted: 09/03/2020] [Indexed: 01/31/2023] Open
Abstract
In insect, pyruvate is generally the predominant oxidative substrate for mitochondria. This metabolite is transported inside mitochondria via the mitochondrial pyruvate carrier (MPC), but whether and how this transporter controls mitochondrial oxidative capacities in insects is still relatively unknown. Here, we characterize the importance of pyruvate transport as a metabolic control point for mitochondrial substrate oxidation in two genotypes of an insect model, Drosophila melanogaster, differently expressing MPC1, an essential protein for the MPC function. We evaluated the kinetics of pyruvate oxidation, mitochondrial oxygen consumption, metabolic profile, activities of metabolic enzymes, and climbing abilities of wild-type (WT) flies and flies harboring a deficiency in MPC1 (MPC1def). We hypothesized that MPC1 deficiency would cause a metabolic reprogramming that would favor the oxidation of alternative substrates. Our results show that the MPC1def flies display significantly reduced climbing capacity, pyruvate-induced oxygen consumption, and enzymatic activities of pyruvate kinase, alanine aminotransferase, and citrate synthase. Moreover, increased proline oxidation capacity was detected in MPC1def flies, which was associated with generally lower levels of several metabolites, and particularly those involved in amino acid catabolism such as ornithine, citrulline, and arginosuccinate. This study therefore reveals the flexibility of mitochondrial substrate oxidation allowing Drosophila to maintain cellular homeostasis.
Collapse
Affiliation(s)
- Chloé Simard
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB E1A 3E9, Canada; (C.S.); (A.L.); (M.T.)
| | - Andréa Lebel
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB E1A 3E9, Canada; (C.S.); (A.L.); (M.T.)
| | | | - Mohamed Touaibia
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB E1A 3E9, Canada; (C.S.); (A.L.); (M.T.)
| | - Etienne Hebert-Chatelain
- Department of Biology, Université de Moncton, Moncton, NB E1A 3E9, Canada;
- Canada Research Chair in Mitochondrial Signaling and Physiopathology, Moncton, NB E1A 3E9, Canada
| | - Nicolas Pichaud
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB E1A 3E9, Canada; (C.S.); (A.L.); (M.T.)
- Correspondence:
| |
Collapse
|
19
|
Chang CH, Zhou XW, Wang YC, Lee TH. Differential effects of hypothermal stress on lactate metabolism in fresh water- and seawater-acclimated milkfish, Chanos chanos. Comp Biochem Physiol A Mol Integr Physiol 2020; 248:110744. [PMID: 32569829 DOI: 10.1016/j.cbpa.2020.110744] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 06/01/2020] [Accepted: 06/08/2020] [Indexed: 10/24/2022]
Abstract
The milkfish Chanos chanos, an economically important cultured marine species in Southeast Asia, exhibits stenothermal and euryhaline characteristics and huge mortality usually occurs during extreme cold weather in winter. Under conditions beyond optimal temperatures, ectothermic species experience an increase in anaerobic glycolysis. To better understand the hypothermal acclimation response of this tropical species, the lactate metabolic profiles of freshwater (FW)- and seawater (SW)-acclimated milkfish were compared under control (optimal temperature; 28 °C) and hypothermal treatment (18 °C) conditions. In this study, the lactate dehydrogenase (LDH) isoform genes, ldha and ldhb, were identified in milkfish livers and muscles, respectively. The LDH is a bidirectional enzyme that triggered the conversion of pyruvate to lactate via anaerobic glycolysis as LDH exhibits the reductase activity (LDH-R), while via the reverse direction as LDH exhibits the oxidase activity (LDH-O). The hypothermal stress significantly upregulated the LDH-R activity in the muscles and the monocarboxylate transporter activity in both muscles and livers, of SW- and FW-acclimated milkfish. The levels of blood lactate, however, decreased in SW-acclimated milkfish. Under hypothermal stress, anaerobic metabolism increased in the muscles of both FW and SW individuals, whereas the liver of SW-acclimated milkfish showed better acute phase capacity to utilize blood lactate than FW-acclimated milkfish. Taken together, in the present study, the major functions of the bidirectional enzyme LDH were identified according to its LDH-O and LDH-R activities. Furthermore, environmental salinities were found to affect the acute anaerobic metabolic strategies of euryhaline teleosts under hypothermal stress and were correlated with their hypothermal tolerance ability.
Collapse
Affiliation(s)
- Chia-Hao Chang
- Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan; The iEGG and Animal Biotechnology Center, National Chung Hsing University, Taichung 402, Taiwan
| | - Xiu-Wei Zhou
- Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan
| | - Yu-Chun Wang
- Planning and Information Division, Fisheries Research Institute, Keelung 202, Taiwan
| | - Tsung-Han Lee
- Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan; The iEGG and Animal Biotechnology Center, National Chung Hsing University, Taichung 402, Taiwan.
| |
Collapse
|
20
|
Illing B, Downie A, Beghin M, Rummer J. Critical thermal maxima of early life stages of three tropical fishes: Effects of rearing temperature and experimental heating rate. J Therm Biol 2020; 90:102582. [DOI: 10.1016/j.jtherbio.2020.102582] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 03/20/2020] [Accepted: 03/31/2020] [Indexed: 01/26/2023]
|
21
|
Jarrold MD, Chakravarti LJ, Gibbin EM, Christen F, Massamba-N'Siala G, Blier PU, Calosi P. Life-history trade-offs and limitations associated with phenotypic adaptation under future ocean warming and elevated salinity. Philos Trans R Soc Lond B Biol Sci 2020; 374:20180428. [PMID: 30966961 DOI: 10.1098/rstb.2018.0428] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Little is known about the life-history trade-offs and limitations, and the physiological mechanisms that are associated with phenotypic adaptation to future ocean conditions. To address this knowledge gap, we investigated the within- and trans-generation life-history responses and aerobic capacity of a marine polychaete, Ophryotrocha labronica, to elevated temperature and elevated temperature combined with elevated salinity for its entire lifespan. In addition, transplants between treatments were carried out at both the egg mass and juvenile stage to identify the potential influence of developmental effects. Within-generation, life-history trade-offs caused by the timing of transplant were only detected under elevated temperature combined with elevated salinity conditions. Polychaetes transplanted at the egg mass stage grew slower and had lower activities of energy metabolism enzymes but reached a larger maximum body size and lived longer when compared with those transplanted as juveniles. Trans-generation exposure to both elevated temperature and elevated temperature and salinity conditions restored 20 and 21% of lifespan fecundity, respectively. Trans-generation exposure to elevated temperature conditions also resulted in a trade-off between juvenile growth rates and lifespan fecundity, with slower growers showing greater fecundity. Overall, our results suggest that future ocean conditions may select for slower growers. Furthermore, our results indicate that life-history trade-offs and limitations will be more prevalent with the shift of multiple global change drivers, and thus there will be greater constraints on adaptive potential. This article is part of the theme issue 'The role of plasticity in phenotypic adaptation to rapid environmental change'.
Collapse
Affiliation(s)
- Michael D Jarrold
- 1 Département de Biologie Chimie et Géographie, Université du Québec à Rimouski , 300 Allée des Ursulines, Rimouski, Quebec, Canada G5L 3A1.,2 College of Science and Engineering, James Cook University , Townsville, Queensland 4811 , Australia
| | - Leela J Chakravarti
- 1 Département de Biologie Chimie et Géographie, Université du Québec à Rimouski , 300 Allée des Ursulines, Rimouski, Quebec, Canada G5L 3A1.,2 College of Science and Engineering, James Cook University , Townsville, Queensland 4811 , Australia
| | - Emma M Gibbin
- 1 Département de Biologie Chimie et Géographie, Université du Québec à Rimouski , 300 Allée des Ursulines, Rimouski, Quebec, Canada G5L 3A1.,3 Laboratory for Biological Geochemistry, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne , Lausanne , Switzerland
| | - Felix Christen
- 1 Département de Biologie Chimie et Géographie, Université du Québec à Rimouski , 300 Allée des Ursulines, Rimouski, Quebec, Canada G5L 3A1
| | - Gloria Massamba-N'Siala
- 1 Département de Biologie Chimie et Géographie, Université du Québec à Rimouski , 300 Allée des Ursulines, Rimouski, Quebec, Canada G5L 3A1.,4 Centre d'Écologie Fonctionnelle et Evolutive (CEFE-CNRS) , UMR 5175, Montpellier Cedex 5 , France
| | - Pierre U Blier
- 1 Département de Biologie Chimie et Géographie, Université du Québec à Rimouski , 300 Allée des Ursulines, Rimouski, Quebec, Canada G5L 3A1
| | - Piero Calosi
- 1 Département de Biologie Chimie et Géographie, Université du Québec à Rimouski , 300 Allée des Ursulines, Rimouski, Quebec, Canada G5L 3A1
| |
Collapse
|
22
|
Isei MO, Kamunde C. Effects of copper and temperature on heart mitochondrial hydrogen peroxide production. Free Radic Biol Med 2020; 147:114-128. [PMID: 31825803 DOI: 10.1016/j.freeradbiomed.2019.12.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 12/05/2019] [Accepted: 12/05/2019] [Indexed: 11/19/2022]
Abstract
High energy demand for continuous mechanical work and large number of mitochondria predispose the heart to excessive reactive oxygen species (ROS) production that may precipitate oxidative stress and heart failure. While mitochondria have been proposed as a unifying cellular target and driver of adverse effects induced by diverse stressful states, there is limited understanding of how heart mitochondrial ROS homeostasis is affected by combinations of stress factors. Thus, we probed the effect of copper (Cu) and thermal stress on ROS (as hydrogen peroxide, H2O2) emission and elucidated the effects of Cu on ROS production sites in rainbow trout heart mitochondria using the Amplex UltraRed-horseradish peroxidase detection system optimized for our model. Mitochondria oxidizing malate-glutamate or succinate were incubated at 4, 11 (control) and 23 °C and exposed to a range (1-100 μM) of Cu concentrations. We found that the rates and patterns of H2O2 emission depended on substrate type, Cu concentration and temperature. In mitochondria oxidizing malate-glutamate, Cu increased the rate of H2O2 emission with a spike at 1 μM while temperature had no effect. In contrast, both temperature and Cu increased the rate of H2O2 emission in mitochondria oxidizing succinate with a prominent spike at 25 μM Cu. The rates of H2O2 emission at the three temperatures during the spike imposed by 25 μM Cu were of the order 11 > 23 > 4 °C. Interestingly, 5 μM Cu supressed H2O2 emission in mitochondria oxidizing succinate or malate-glutamate suggesting a common mechanism of action independent of substrate type. In the absence of Cu, the site-specific capacities of H2O2 emission were: complex III outer ubiquinone binding site (site IIIQo) > complex II flavin site (site IIF) ≥ complex I flavin site (site IF) > complex I ubiquinone-binding site (site IQ). Rotenone marginally increased succinate-driven H2O2 emission suggesting either the absence of reverse electron transport (RET)-driven ROS production at site IQ or masking of the expected rotenone response (reduction) by H2O2 produced from other sites. Cu acted at multiple sites in the electron transport system resulting in different site-specific H2O2 emission responses depending on the concentration. Specifically, site IF H2O2 emission was suppressed by Cu concentration-dependently while H2O2 emission by site IIF was inhibited and stimulated by low and high concentrations of Cu, respectively. Additionally, emission from site IIIQo was stimulated by low and inhibited by high Cu concentrations. Overall, our study unveiled distinctive effects and sites of modulation of mitochondrial ROS production by Cu with implications for cardiac redox signaling networks and development of mitochondria-targeted Cu-based drugs.
Collapse
Affiliation(s)
- Michael O Isei
- Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PE, C1A 4P3, Canada
| | - Collins Kamunde
- Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PE, C1A 4P3, Canada.
| |
Collapse
|
23
|
Christen F, Dufresne F, Leduc G, Dupont-Cyr BA, Vandenberg GW, Le François NR, Tardif JC, Lamarre SG, Blier PU. Thermal tolerance and fish heart integrity: fatty acids profiles as predictors of species resilience. CONSERVATION PHYSIOLOGY 2020; 8:coaa108. [PMID: 33408863 PMCID: PMC7771578 DOI: 10.1093/conphys/coaa108] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 10/21/2020] [Accepted: 11/20/2020] [Indexed: 05/05/2023]
Abstract
The cardiovascular system is a major limiting system in thermal adaptation, but the exact physiological mechanisms underlying responses to thermal stress are still not completely understood. Recent studies have uncovered the possible role of reactive oxygen species production rates of heart mitochondria in determining species' upper thermal limits. The present study examines the relationship between individual response to a thermal challenge test (CTmax), susceptibility to peroxidation of membrane lipids, heart fatty acid profiles and cardiac antioxidant enzyme activities in two salmonid species from different thermal habitats (Salvelinus alpinus, Salvelinus fontinalis) and their hybrids. The susceptibility to peroxidation of membranes in the heart was negatively correlated with individual thermal tolerance. The same relationship was found for arachidonic and eicosapentaenoic acid. Total H2O2 buffering activity of the heart muscle was higher for the group with high thermal resistance. These findings underline a potential general causative relationship between sensitivity to oxidative stress, specific fatty acids, antioxidant activity in the cardiac muscle and thermal tolerance in fish and likely other ectotherms. Heart fatty acid profile could be indicative of species resilience to global change, and more importantly the plasticity of this trait could predict the adaptability of fish species or populations to changes in environmental temperature.
Collapse
Affiliation(s)
- Felix Christen
- Département de Biologie, Université du Québec à Rimouski, Rimouski, Québec, G5L3A1, Canada
| | - France Dufresne
- Département de Biologie, Université du Québec à Rimouski, Rimouski, Québec, G5L3A1, Canada
| | - Gabriel Leduc
- Département de Biologie, Université du Québec à Rimouski, Rimouski, Québec, G5L3A1, Canada
| | - Bernard A Dupont-Cyr
- Département de Biologie, Université du Québec à Rimouski, Rimouski, Québec, G5L3A1, Canada
| | - Grant W Vandenberg
- Département de Sciences Animales, Université Laval, Québec, Québec, G1V 0A6, Canada
| | | | - Jean-Claude Tardif
- Montreal Heart Institute, Université de Montréal, Montréal, Québec, H1T 1C8, Canada
| | - Simon G Lamarre
- Département de Biologie, Université de Moncton, Moncton, New-Brunswick, E1A 3E9, Canada
| | - Pierre U Blier
- Département de Biologie, Université du Québec à Rimouski, Rimouski, Québec, G5L3A1, Canada
- Corresponding author: Département de Biologie, Université du Québec à Rimouski, Rimouski, Québec, G5L3A1, Canada.
| |
Collapse
|
24
|
Havird JC, Shah AA, Chicco AJ. Powerhouses in the cold: mitochondrial function during thermal acclimation in montane mayflies. Philos Trans R Soc Lond B Biol Sci 2019; 375:20190181. [PMID: 31787050 DOI: 10.1098/rstb.2019.0181] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Mitochondria provide the vast majority of cellular energy available to eukaryotes. Therefore, adjustments in mitochondrial function through genetic changes in mitochondrial or nuclear-encoded genes might underlie environmental adaptation. Environmentally induced plasticity in mitochondrial function is also common, especially in response to thermal acclimation in aquatic systems. Here, we examined mitochondrial function in mayfly larvae (Baetis and Drunella spp.) from high and low elevation mountain streams during thermal acclimation to ecologically relevant temperatures. A multi-substrate titration protocol was used to evaluate different respiratory states in isolated mitochondria, along with cytochrome oxidase and citrate synthase activities. In general, maximal mitochondrial respiratory capacity and oxidative phosphorylation coupling efficiency decreased during acclimation to higher temperatures, suggesting montane insects may be especially vulnerable to rapid climate change. Consistent with predictions of the climate variability hypothesis, mitochondria from Baetis collected at a low elevation site with highly variable daily and seasonal temperatures exhibited greater thermal tolerance than Baetis from a high elevation site with comparatively stable temperatures. However, mitochondrial phenotypes were more resilient than whole-organism phenotypes in the face of thermal stress. These results highlight the complex relationships between mitochondrial and organismal genotypes, phenotypes and environmental adaptation. This article is part of the theme issue 'Linking the mitochondrial genotype to phenotype: a complex endeavour'.
Collapse
Affiliation(s)
- Justin C Havird
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Alisha A Shah
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Adam J Chicco
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| |
Collapse
|
25
|
Pichaud N, Ekström A, Breton S, Sundström F, Rowinski P, Blier PU, Sandblom E. Cardiac mitochondrial plasticity and thermal sensitivity in a fish inhabiting an artificially heated ecosystem. Sci Rep 2019; 9:17832. [PMID: 31780821 PMCID: PMC6883045 DOI: 10.1038/s41598-019-54165-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 11/06/2019] [Indexed: 12/03/2022] Open
Abstract
Some evidence suggests that cardiac mitochondrial functions might be involved in the resilience of ectotherms such as fish to environmental warming. Here, we investigated the effects of acute and chronic changes in thermal regimes on cardiac mitochondrial plasticity and thermal sensitivity in perch (Perca fluviatilis) from an artificially heated ecosystem; the “Biotest enclosure” (~25 °C), and from an adjacent area in the Baltic Sea with normal temperatures (reference, ~16 °C). We evaluated cardiac mitochondrial respiration at assay temperatures of 16 and 25 °C, as well as activities of lactate dehydrogenase (LDH) and citrate synthase (CS) in Biotest and reference perch following 8 months laboratory-acclimation to either 16 or 25 °C. While both populations exhibited higher acute mitochondrial thermal sensitivity when acclimated to their natural habitat temperatures, this sensitivity was lost when Biotest and reference fish were acclimated to 16 and 25 °C, respectively. Moreover, reference fish displayed patterns of metabolic thermal compensation when acclimated to 25 °C, whereas no changes were observed in Biotest perch acclimated to 16 °C, suggesting that cardiac mitochondrial metabolism of Biotest fish expresses local adaptation. This study highlights the adaptive responses of cardiac mitochondria to environmental warming, which can impact on fish survival and distribution in a warming climate.
Collapse
Affiliation(s)
- Nicolas Pichaud
- Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, E1 A 3E9, Canada. .,Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, 405 30, Sweden. .,Department of Biology, Université du Québec à Rimouski, Rimouski, QC, Canada, G5L 3A1.
| | - Andreas Ekström
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, 405 30, Sweden
| | - Sophie Breton
- Department of Biological Sciences, Université de Montréal, Montréal, QC, H2V 2S9, Canada
| | - Fredrik Sundström
- Department of Ecology and Genetics, Uppsala University, Uppsala, 752 36, Sweden
| | - Piotr Rowinski
- Department of Ecology and Genetics, Uppsala University, Uppsala, 752 36, Sweden
| | - Pierre U Blier
- Department of Biology, Université du Québec à Rimouski, Rimouski, QC, Canada, G5L 3A1
| | - Erik Sandblom
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, 405 30, Sweden
| |
Collapse
|
26
|
Howald S, Cominassi L, LeBayon N, Claireaux G, Mark FC. Future ocean warming may prove beneficial for the northern population of European seabass, but ocean acidification will not. ACTA ACUST UNITED AC 2019; 222:jeb.213017. [PMID: 31624098 DOI: 10.1242/jeb.213017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 10/01/2019] [Indexed: 12/26/2022]
Abstract
The world's oceans are acidifying and warming as a result of increasing atmospheric CO2 concentrations. The thermal tolerance of fish greatly depends on the cardiovascular ability to supply the tissues with oxygen. The highly oxygen-dependent heart mitochondria thus might play a key role in shaping an organism's tolerance to temperature. The present study aimed to investigate the effects of acute and chronic warming on the respiratory capacity of European sea bass (Dicentrarchus labrax L.) heart mitochondria. We hypothesized that acute warming would impair mitochondrial respiratory capacity, but be compensated for by life-time conditioning. Increasing P CO2 may additionally cause shifts in metabolic pathways by inhibiting several enzymes of the cellular energy metabolism. Among other shifts in metabolic pathways, acute warming of heart mitochondria of cold life-conditioned fish increased leak respiration rate, suggesting a lower aerobic capacity to synthesize ATP with acute warming. However, thermal conditioning increased mitochondrial functionality, e.g. higher respiratory control ratios in heart mitochondria of warm life-conditioned compared with cold life-conditioned fish. Exposure to high P CO2 synergistically amplified the effects of acute and long-term warming, but did not result in changes by itself. This high ability to maintain mitochondrial function under ocean acidification can be explained by the fact that seabass are generally able to acclimate to a variety of environmental conditions. Improved mitochondrial energy metabolism after warm conditioning could be due to the origin of this species in the warm waters of the Mediterranean. Our results also indicate that seabass are not yet fully adapted to the colder temperatures in their northern distribution range and might benefit from warmer temperatures in these latitudes.
Collapse
Affiliation(s)
- Sarah Howald
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Integrative Ecophysiology, 27570 Bremerhaven, Germany .,Institute of Marine Ecosystem and Fisheries Science, Center for Earth System Research and Sustainability (CEN), University of Hamburg, 22767 Hamburg, Germany
| | - Louise Cominassi
- Institute of Marine Ecosystem and Fisheries Science, Center for Earth System Research and Sustainability (CEN), University of Hamburg, 22767 Hamburg, Germany
| | - Nicolas LeBayon
- Ifremer, LEMAR (UMR 6539), Laboratory of Adaptation, and Nutrition of Fish, Centre Ifremer de Bretagne, 29280 Plouzané, France
| | - Guy Claireaux
- Ifremer, LEMAR (UMR 6539), Laboratory of Adaptation, and Nutrition of Fish, Centre Ifremer de Bretagne, 29280 Plouzané, France.,Université de Bretagne Occidentale, LEMAR (UMR 6539), 29280 Plouzané, France
| | - Felix C Mark
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Integrative Ecophysiology, 27570 Bremerhaven, Germany
| |
Collapse
|
27
|
Hunter-Manseau F, Desrosiers V, Le François NR, Dufresne F, Detrich HW, Nozais C, Blier PU. From Africa to Antarctica: Exploring the Metabolism of Fish Heart Mitochondria Across a Wide Thermal Range. Front Physiol 2019; 10:1220. [PMID: 31636568 PMCID: PMC6788138 DOI: 10.3389/fphys.2019.01220] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 09/06/2019] [Indexed: 12/18/2022] Open
Abstract
The thermal sensitivity of ectotherms is largely dictated by the impact of temperature on cellular bioenergetics, particularly on mitochondrial functions. As the thermal sensitivity of bioenergetic pathways depends on the structural and kinetic properties of its component enzymes, optimization of their collective function to different thermal niches is expected to have occurred through selection. In the present study, we sought to characterize mitochondrial phenotypic adjustments to thermal niches in eight ray-finned fish species occupying a wide range of thermal habitats by comparing the activities of key mitochondrial enzymes in their hearts. We measured the activity of four enzymes that control substrate entrance into the tricarboxylic acid (TCA) cycle: pyruvate kinase (PK), pyruvate dehydrogenase complex (PDHc), carnitine palmitoyltransferase (CPT), and hydroxyacyl-CoA dehydrogenase (HOAD). We also assayed enzymes of the electron transport system (ETS): complexes I, II, I + III, and IV. Enzymes were assayed at five temperatures (5, 10, 15, 20, and 25°C). Our results showed that the activity of CPT, a gatekeeper of the fatty acid pathway, was higher in the cold-water fish than in the warmer-adapted fish relative to the ETS (complexes I and III) when measured close to the species optimal temperatures. The activity of HOAD showed a similar pattern relative to CI + III and thermal environment. By contrast, PDHc and PK did not show the similar patterns with respect to CI + III and temperature. Cold-adapted species had high CIV activities compared to those of upstream complexes (I, II, I + III) whereas the converse was true for warm-adapted species. Our findings reveal a significant variability of heart mitochondrial organization among species that can be linked to temperature adaptation. Cold-adapted fish do not appear to compensate for PDHc activity but likely adjust fatty acids oxidation through higher activities of CPT and HOAD relative to complexes I + III.
Collapse
Affiliation(s)
| | | | | | - France Dufresne
- Département de Biologie, Université du Québec à Rimouski, Rimouski, QC, Canada
| | - H. William Detrich
- Department of Marine and Environmental Sciences, Northeastern University Marine Science Center, Nahant, MA, United States
| | - Christian Nozais
- Département de Biologie, Université du Québec à Rimouski, Rimouski, QC, Canada
| | - Pierre U. Blier
- Département de Biologie, Université du Québec à Rimouski, Rimouski, QC, Canada
| |
Collapse
|
28
|
Morgenroth D, Ekström A, Hjelmstedt P, Gräns A, Axelsson M, Sandblom E. Hemodynamic responses to warming in euryhaline rainbow trout: implications of the osmo-respiratory compromise. ACTA ACUST UNITED AC 2019; 222:jeb.207522. [PMID: 31395678 DOI: 10.1242/jeb.207522] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 07/31/2019] [Indexed: 12/19/2022]
Abstract
In seawater, rainbow trout (Oncorhynchus mykiss) drink and absorb water through the gastrointestinal tract to compensate for water passively lost to the hyperosmotic environment. Concomitantly, they exhibit elevated cardiac output and a doubling of gastrointestinal blood flow to provide additional O2 to the gut and increase convective flux of absorbed ions and water. Yet, it is unknown how warming waters, which elevate tissue O2 demand and the rate of diffusion of ions and water across the gills (i.e. the osmo-respiratory compromise), affects these processes. We measured cardiovascular and blood variables of rainbow trout acclimated to freshwater and seawater during acute warming from 11 to 17°C. Relative to freshwater-acclimated trout, cardiac output was 34% and 55% higher in seawater-acclimated trout at 11 and 17°C, respectively, which allowed them to increase gastrointestinal blood flow significantly more during warming (increases of 75% in seawater vs. 31% in freshwater). These adjustments likely served to mitigate the impact of warming on osmotic balance, as changes in ionic and osmotic blood composition were minor. Furthermore, seawater-acclimated trout seemingly had a lower tissue O2 extraction, explaining why trout acclimated to freshwater and seawater often exhibit similar metabolic rates, despite a higher cardiac output in seawater. Our results highlight a novel role of gastrointestinal blood perfusion in the osmo-respiratory compromise in fish, and improve our understanding of the physiological changes euryhaline fishes must undergo when faced with interacting environmental challenges such as transient warming events.
Collapse
Affiliation(s)
- Daniel Morgenroth
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
| | - Andreas Ekström
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
| | - Per Hjelmstedt
- Department of Animal Environment and Health, Swedish University of Agricultural Sciences, 532 23 Skara, Sweden
| | - Albin Gräns
- Department of Animal Environment and Health, Swedish University of Agricultural Sciences, 532 23 Skara, Sweden
| | - Michael Axelsson
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
| | - Erik Sandblom
- Department of Biological and Environmental Sciences, University of Gothenburg, PO Box 463, 405 30 Gothenburg, Sweden
| |
Collapse
|
29
|
Makaras T, Montvydienė D, Kazlauskienė N, Stankevičiūtė M. Rapidness- and Sensitivity-Based Comparison of Behavioral and Respiratory Responses of European Perch and Rainbow Trout to Metal Mixture Exposure. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2019; 103:391-399. [PMID: 31338521 DOI: 10.1007/s00128-019-02682-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 07/13/2019] [Indexed: 06/10/2023]
Abstract
The aim of the study was to investigate acute (96-h LC50) toxicity of the complex metal (Zn, Pb, Cd, Cu, Ni and Cr) mixture (MIX) to European perch (Perca fluviatilis) and rainbow trout (Oncorhynchus mykiss), and to examine differences between locomotor and respiratory endpoints based on rapidness and sensitivity of fish responses to short-term (2 h) metal mixture exposure. MIX was prepared taking into consideration the maximum-permissible-concentrations (MPC) set for these metals in EU inland waters (Directive 2008/105/EC). The studied behavioral and respiratory responses of O. mykiss, in contrast to those of P. fluviatilis, were found to be significantly affected by the relationship between exposure duration and treatment. In O. mykiss, gill ventilation frequency (GVF) was found to be the most rapid and sensitive endpoint of all the investigated ones. However, the investigated behavioral and respiratory endpoints of P. fluviatilis showed its behavioral insensitivity to MIX exposure.
Collapse
Affiliation(s)
- Tomas Makaras
- Nature Research Centre, Akademijos St. 2, 08412, Vilnius, Lithuania.
| | | | | | | |
Collapse
|
30
|
Salem M, Al-Tobasei R, Ali A, Lourenco D, Gao G, Palti Y, Kenney B, Leeds TD. Genome-Wide Association Analysis With a 50K Transcribed Gene SNP-Chip Identifies QTL Affecting Muscle Yield in Rainbow Trout. Front Genet 2018; 9:387. [PMID: 30283492 PMCID: PMC6157414 DOI: 10.3389/fgene.2018.00387] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 08/27/2018] [Indexed: 11/13/2022] Open
Abstract
Detection of coding/functional SNPs that change the biological function of a gene may lead to identification of putative causative alleles within QTL regions and discovery of genetic markers with large effects on phenotypes. This study has two-fold objectives, first to develop, and validate a 50K transcribed gene SNP-chip using RNA-Seq data. To achieve this objective, two bioinformatics pipelines, GATK and SAMtools, were used to identify ~21K transcribed SNPs with allelic imbalances associated with important aquaculture production traits including body weight, muscle yield, muscle fat content, shear force, and whiteness in addition to resistance/susceptibility to bacterial cold-water disease (BCWD). SNPs ere identified from pooled RNA-Seq data collected from ~620 fish, representing 98 families from growth- and 54 families from BCWD-selected lines with divergent phenotypes. In addition, ~29K transcribed SNPs without allelic-imbalances were strategically added to build a 50K Affymetrix SNP-chip. SNPs selected included two SNPs per gene from 14K genes and ~5K non-synonymous SNPs. The SNP-chip was used to genotype 1728 fish. The average SNP calling-rate for samples passing quality control (QC; 1,641 fish) was ≥ 98.5%. The second objective of this study was to test the feasibility of using the new SNP-chip in GWA (Genome-wide association) analysis to identify QTL explaining muscle yield variance. GWA study on 878 fish (representing 197 families from 2 consecutive generations) with muscle yield phenotypes and genotyped for 35K polymorphic markers (passing QC) identified several QTL regions explaining together up to 28.40% of the additive genetic variance for muscle yield in this rainbow trout population. The most significant QTLs were on chromosomes 14 and 16 with 12.71 and 10.49% of the genetic variance, respectively. Many of the annotated genes in the QTL regions were previously reported as important regulators of muscle development and cell signaling. No major QTLs were identified in a previous GWA study using a 57K genomic SNP chip on the same fish population. These results indicate improved detection power of the transcribed gene SNP-chip in the target trait and population, allowing identification of large-effect QTLs for important traits in rainbow trout.
Collapse
Affiliation(s)
- Mohamed Salem
- Department of Biology and Molecular Biosciences Program, Middle Tennessee State University, Murfreesboro, TN, United States.,Computational Science Program, Middle Tennessee State University, Murfreesboro, TN, United States
| | - Rafet Al-Tobasei
- Computational Science Program, Middle Tennessee State University, Murfreesboro, TN, United States.,Department of Biostatistics, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Ali Ali
- Department of Biology and Molecular Biosciences Program, Middle Tennessee State University, Murfreesboro, TN, United States
| | - Daniela Lourenco
- Department of Animal and Dairy Science, University of Georgia, Athens, GA, United States
| | - Guangtu Gao
- National Center for Cool and Cold Water Aquaculture, USDA Agricultural Research Service, Kearneysville, WV, United States
| | - Yniv Palti
- National Center for Cool and Cold Water Aquaculture, USDA Agricultural Research Service, Kearneysville, WV, United States
| | - Brett Kenney
- Division of Animal and Nutritional Science, West Virginia University, Morgantown, WV, United States
| | - Timothy D Leeds
- National Center for Cool and Cold Water Aquaculture, USDA Agricultural Research Service, Kearneysville, WV, United States
| |
Collapse
|
31
|
O'Brien KM, Rix AS, Egginton S, Farrell AP, Crockett EL, Schlauch K, Woolsey R, Hoffman M, Merriman S. Cardiac mitochondrial metabolism may contribute to differences in thermal tolerance of red- and white-blooded Antarctic notothenioid fishes. J Exp Biol 2018; 221:jeb177816. [PMID: 29895681 PMCID: PMC6104818 DOI: 10.1242/jeb.177816] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 06/04/2018] [Indexed: 12/18/2022]
Abstract
Studies in temperate fishes provide evidence that cardiac mitochondrial function and the capacity to fuel cardiac work contribute to thermal tolerance. Here, we tested the hypothesis that decreased cardiac aerobic metabolic capacity contributes to the lower thermal tolerance of the haemoglobinless Antarctic icefish, Chaenocephalus aceratus, compared with that of the red-blooded Antarctic species, Notothenia coriiceps. Maximal activities of citrate synthase (CS) and lactate dehydrogenase (LDH), respiration rates of isolated mitochondria, adenylate levels and changes in mitochondrial protein expression were quantified from hearts of animals held at ambient temperature or exposed to their critical thermal maximum (CTmax). Compared with C. aceratus, activity of CS, ATP concentration and energy charge were higher in hearts of N. coriiceps at ambient temperature and CTmax While state 3 mitochondrial respiration rates were not impaired by exposure to CTmax in either species, state 4 rates, indicative of proton leakage, increased following exposure to CTmax in C. aceratus but not N. coriiceps The interactive effect of temperature and species resulted in an increase in antioxidants and aerobic metabolic enzymes in N. coriiceps but not in C. aceratus Together, our results support the hypothesis that the lower aerobic metabolic capacity of C. aceratus hearts contributes to its low thermal tolerance.
Collapse
Affiliation(s)
- Kristin M O'Brien
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - Anna S Rix
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - Stuart Egginton
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Anthony P Farrell
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
| | | | - Karen Schlauch
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV 89557, USA
| | - Rebekah Woolsey
- Nevada Proteomics Center, University of Nevada, Reno, NV 89557, USA
| | - Megan Hoffman
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - Sean Merriman
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| |
Collapse
|
32
|
Muñoz NJ, Farrell AP, Heath JW, Neff BD. Hematocrit Is Associated with Thermal Tolerance and Modulated by Developmental Temperature in Juvenile Chinook Salmon. Physiol Biochem Zool 2018; 91:757-762. [DOI: 10.1086/695556] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
|
33
|
Brijs J, Sandblom E, Sundh H, Gräns A, Hinchcliffe J, Ekström A, Sundell K, Olsson C, Axelsson M, Pichaud N. Increased mitochondrial coupling and anaerobic capacity minimizes aerobic costs of trout in the sea. Sci Rep 2017; 7:45778. [PMID: 28361996 PMCID: PMC5374462 DOI: 10.1038/srep45778] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 03/01/2017] [Indexed: 12/16/2022] Open
Abstract
Anadromy is a distinctive life-history strategy in fishes that has evolved independently many times. In an evolutionary context, the benefits of anadromy for a species or population must outweigh the costs and risks associated with the habitat switch. The migration of fish across the freshwater-ocean boundary coincides with potentially energetically costly osmoregulatory modifications occurring at numerous levels of biological organization. By integrating whole animal and sub-cellular metabolic measurements, this study presents significant findings demonstrating how an anadromous salmonid (i.e. rainbow trout, Oncorhynchus mykiss) is able to transform from a hyper- to hypo-osmoregulatory state without incurring significant increases in whole animal oxygen consumption rate. Instead, underlying metabolic mechanisms that fuel the osmoregulatory machinery at the organ level (i.e. intestine) are modulated, as mitochondrial coupling and anaerobic metabolism are increased to satisfy the elevated energetic demands. This may have positive implications for the relative fitness of the migrating individual, as aerobic capacity may be maintained for locomotion (i.e. foraging and predator avoidance) and growth. Furthermore, the ability to modulate mitochondrial metabolism in order to maintain osmotic balance suggests that mitochondria of anadromous fish may have been a key target for natural selection, driving species adaptations to different aquatic environments.
Collapse
Affiliation(s)
- Jeroen Brijs
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Erik Sandblom
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Henrik Sundh
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Albin Gräns
- Department of Animal Environment and Health, Swedish University of Agricultural Sciences, Skara, Sweden
| | - James Hinchcliffe
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Andreas Ekström
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Kristina Sundell
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Catharina Olsson
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Michael Axelsson
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Nicolas Pichaud
- Département de chimie et biochimie, Université de Moncton, Moncton, NB, Canada
| |
Collapse
|
34
|
Pichaud N, Ekström A, Hellgren K, Sandblom E. Dynamic changes in cardiac mitochondrial metabolism during warm acclimation in rainbow trout. ACTA ACUST UNITED AC 2017; 220:1674-1683. [PMID: 28202582 DOI: 10.1242/jeb.152421] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2016] [Accepted: 02/13/2017] [Indexed: 01/06/2023]
Abstract
Although the mitochondrial metabolism responses to warm acclimation have been widely studied in fish, the time course of this process is less understood. Here, we characterized the changes of rainbow trout (Oncorhynchus mykiss) cardiac mitochondrial metabolism during acute warming from 10 to 16°C, and during the subsequent warm acclimation for 39 days. We repeatedly measured mitochondrial oxygen consumption in cardiac permeabilized fibers and the functional integrity of mitochondria (i.e. mitochondrial coupling and cytochrome c effect) at two assay temperatures (10 and 16°C), as well as the activities of citrate synthase (CS) and lactate dehydrogenase (LDH) at room temperature. LDH and CS activities significantly increased between day 0 (10°C acclimated fish) and day 1 (acute warming to 16°C) while mitochondrial oxygen consumption measured at respective in vivo temperatures did not change. Enzymatic activities and mitochondrial oxygen consumption rates significantly decreased by day 2, and remained stable during warm acclimation (days 2-39). The decrease in rates of oxygen between day 0 and day 1 coincided with an increased cytochrome c effect and a decreased mitochondrial coupling, suggesting a structural/functional impairment of mitochondria during acute warming. We suggest that after 2 days of warm acclimation, a new homeostasis is reached, which may involve the removal of dysfunctional mitochondria. Interestingly, from day 2 onwards, there was a lack of differences in mitochondrial oxygen consumption rates between the assay temperatures, suggesting that warm acclimation reduces the acute thermal sensitivity of mitochondria. This study provides significant knowledge on the thermal sensitivity of cardiac mitochondria that is essential to delineate the contribution of cellular processes to warm acclimation.
Collapse
Affiliation(s)
- Nicolas Pichaud
- Department of Chemistry and Biochemistry, University of Moncton, Moncton, New Brunswick, Canada E1A 3E9 .,Department of Biological and Environmental Sciences, University of Gothenburg, SE-405 30 Gothenburg, Sweden
| | - Andreas Ekström
- Department of Biological and Environmental Sciences, University of Gothenburg, SE-405 30 Gothenburg, Sweden
| | - Kim Hellgren
- Department of Biological and Environmental Sciences, University of Gothenburg, SE-405 30 Gothenburg, Sweden
| | - Erik Sandblom
- Department of Biological and Environmental Sciences, University of Gothenburg, SE-405 30 Gothenburg, Sweden
| |
Collapse
|
35
|
|