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Szabla N, Maria Labecka A, Antoł A, Sobczyk Ł, Angilletta MJ, Czarnoleski M. Evolution and development of Drosophila melanogaster under different thermal conditions affected cell sizes and sensitivity to paralyzing hypoxia. JOURNAL OF INSECT PHYSIOLOGY 2024; 157:104671. [PMID: 38972633 DOI: 10.1016/j.jinsphys.2024.104671] [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: 04/15/2024] [Revised: 06/29/2024] [Accepted: 07/04/2024] [Indexed: 07/09/2024]
Abstract
Environmental gradients cause evolutionary and developmental changes in the cellular composition of organisms, but the physiological consequences of these effects are not well understood. Here, we studied experimental populations of Drosophila melanogaster that had evolved in one of three selective regimes: constant 16 °C, constant 25 °C, or intergenerational shifts between 16 °C and 25 °C. Genotypes from each population were reared at three developmental temperatures (16 °C, 20.5 °C, and 25 °C). As adults, we measured thorax length and cell sizes in the Malpighian tubules and wing epithelia of flies from each combination of evolutionary and developmental temperatures. We also exposed flies from these treatments to a short period of nearly complete oxygen deprivation to measure hypoxia tolerance. For genotypes from any selective regime, development at a higher temperature resulted in smaller flies with smaller cells, regardless of the tissue. At every developmental temperature, genotypes from the warm selective regime had smaller bodies and smaller wing cells but had larger tubule cells than did genotypes from the cold selective regime. Genotypes from the fluctuating selective regime were similar in size to those from the cold selective regime, but their cells of either tissue were the smallest among the three regimes. Evolutionary and developmental treatments interactively affected a fly's sensitivity to short-term paralyzing hypoxia. Genotypes from the cold selective regime were less sensitive to hypoxia after developing at a higher temperature. Genotypes from the other selective regimes were more sensitive to hypoxia after developing at a higher temperature. Our results show that thermal conditions can trigger evolutionary and developmental shifts in cell size, coupled with changes in body size and hypoxia tolerance. These patterns suggest links between the cellular composition of the body, levels of hypoxia within cells, and the energetic cost of tissue maintenance. However, the patterns can be only partially explained by existing theories about the role of cell size in tissue oxygenation and metabolic performance.
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Affiliation(s)
- Natalia Szabla
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland
| | - Anna Maria Labecka
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland
| | - Andrzej Antoł
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland; MR Consulting Sp. z o.o. Środowiskowa sp.k., Szosa Chełmińska 177-181, 87-100 Toruń, Poland
| | - Łukasz Sobczyk
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland
| | | | - Marcin Czarnoleski
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
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Privalova V, Sobczyk Ł, Szlachcic E, Labecka AM, Czarnoleski M. Heat tolerance in Drosophila melanogaster is influenced by oxygen conditions and mutations in cell size control pathways. Philos Trans R Soc Lond B Biol Sci 2024; 379:20220490. [PMID: 38186282 PMCID: PMC10772611 DOI: 10.1098/rstb.2022.0490] [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: 06/30/2023] [Accepted: 10/17/2023] [Indexed: 01/09/2024] Open
Abstract
Understanding metabolic performance limitations is key to explaining the past, present and future of life. We investigated whether heat tolerance in actively flying Drosophila melanogaster is modified by individual differences in cell size and the amount of oxygen in the environment. We used two mutants with loss-of-function mutations in cell size control associated with the target of rapamycin (TOR)/insulin pathways, showing reduced (mutant rictorΔ2) or increased (mutant Mnt1) cell size in different body tissues compared to controls. Flies were exposed to a steady increase in temperature under normoxia and hypoxia until they collapsed. The upper critical temperature decreased in response to each mutation type as well as under hypoxia. Females, which have larger cells than males, had lower heat tolerance than males. Altogether, mutations in cell cycle control pathways, differences in cell size and differences in oxygen availability affected heat tolerance, but existing theories on the roles of cell size and tissue oxygenation in metabolic performance can only partially explain our results. A better understanding of how the cellular composition of the body affects metabolism may depend on the development of research models that help separate various interfering physiological parameters from the exclusive influence of cell size. This article is part of the theme issue 'The evolutionary significance of variation in metabolic rates'.
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Affiliation(s)
- Valeriya Privalova
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland
| | - Łukasz Sobczyk
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland
| | - Ewa Szlachcic
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland
| | - Anna Maria Labecka
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland
| | - Marcin Czarnoleski
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland
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Czarnoleski M, Szlachcic E, Privalova V, Maria Labecka A, Sikorska A, Sobczyk Ł, VandenBrooks J, Angilletta MJ. Oxygen and temperature affect cell sizes differently among tissues and between sexes of Drosophila melanogaster. JOURNAL OF INSECT PHYSIOLOGY 2023; 150:104559. [PMID: 37640139 DOI: 10.1016/j.jinsphys.2023.104559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 08/24/2023] [Accepted: 08/25/2023] [Indexed: 08/31/2023]
Abstract
Spatio-temporal gradients in thermal and oxygen conditions trigger evolutionary and developmental responses in ectotherms' body size and cell size, which are commonly interpreted as adaptive. However, the evidence for cell-size responses is fragmentary, as cell size is typically assessed in single tissues. In a laboratory experiment, we raised genotypes of Drosophila melanogaster at all combinations of two temperatures (16 °C or 25 °C) and two oxygen levels (10% or 22%) and measured body size and the sizes of cells in different tissues. For each sex, we measured epidermal cells in a wing and a leg and ommatidial cells of an eye. For males, we also measured epithelial cells of a Malpighian tubule and muscle cells of a flight muscle. On average, females emerged at a larger body size than did males, having larger cells in all tissues. Flies of either sex emerged at a smaller body size when raised under warm or hypoxic conditions. Development at 25 °C resulted in smaller cells in most tissues. Development under hypoxia resulted in smaller cells in some tissues, especially among females. Altogether, our results show thermal and oxygen conditions trigger shifts in adult size, coupled with the systemic orchestration of cell sizes throughout the body of a fly. The nature of these patterns supports a model in which an ectotherm adjusts its life-history traits and cellular composition to prevent severe hypoxia at the cellular level. However, our results revealed some inconsistencies linked to sex, cell type, and environmental parameters, which suggest caution in translating information obtained for single type of cells to the organism as a whole.
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Affiliation(s)
- Marcin Czarnoleski
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
| | - Ewa Szlachcic
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
| | - Valeriya Privalova
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
| | - Anna Maria Labecka
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
| | - Anna Sikorska
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
| | - Łukasz Sobczyk
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
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Szlachcic E, Dańko MJ, Czarnoleski M. Rapamycin supplementation of Drosophila melanogaster larvae results in less viable adults with smaller cells. ROYAL SOCIETY OPEN SCIENCE 2023; 10:230080. [PMID: 37351490 PMCID: PMC10282583 DOI: 10.1098/rsos.230080] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 05/30/2023] [Indexed: 06/24/2023]
Abstract
The intrinsic sources of mortality relate to the ability to meet the metabolic demands of tissue maintenance and repair, ultimately shaping ageing patterns. Anti-ageing mechanisms compete for resources with other functions, including those involved in maintaining functional plasma membranes. Consequently, organisms with smaller cells and more plasma membranes should devote more resources to membrane maintenance, leading to accelerated intrinsic mortality and ageing. To investigate this unexplored trade-off, we reared Drosophila melanogaster larvae on food with or without rapamycin (a TOR pathway inhibitor) to produce small- and large-celled adult flies, respectively, and measured their mortality rates. Males showed higher mortality than females. As expected, small-celled flies (rapamycin) showed higher mortality than their large-celled counterparts (control), but only in early adulthood. Contrary to predictions, the median lifespan was similar between the groups. Rapamycin administered to adults prolongs life; thus, the known direct physiological effects of rapamycin cannot explain our results. Instead, we invoke indirect effects of rapamycin, manifested as reduced cell size, as a driver of increased early mortality. We conclude that cell size differences between organisms and the associated burdens of plasma membrane maintenance costs may be important but overlooked factors influencing mortality patterns in nature.
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Affiliation(s)
- Ewa Szlachcic
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Kraków, Poland
| | - Maciej J. Dańko
- Max Planck Institute for Demographic Research, Rostock, Germany
| | - Marcin Czarnoleski
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Kraków, Poland
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Privalova V, Labecka AM, Szlachcic E, Sikorska A, Czarnoleski M. Systemic changes in cell size throughout the body of Drosophila melanogaster associated with mutations in molecular cell cycle regulators. Sci Rep 2023; 13:7565. [PMID: 37160985 PMCID: PMC10169805 DOI: 10.1038/s41598-023-34674-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 05/05/2023] [Indexed: 05/11/2023] Open
Abstract
Along with different life strategies, organisms have evolved dramatic cellular composition differences. Understanding the molecular basis and fitness effects of these differences is key to elucidating the fundamental characteristics of life. TOR/insulin pathways are key regulators of cell size, but whether their activity determines cell size in a systemic or tissue-specific manner awaits exploration. To that end, we measured cells in four tissues in genetically modified Drosophila melanogaster (rictorΔ2 and Mnt1) and corresponding controls. While rictorΔ2 flies lacked the Rictor protein in TOR complex 2, downregulating the functions of this element in TOR/insulin pathways, Mnt1 flies lacked the transcriptional regulator protein Mnt, weakening the suppression of downstream signalling from TOR/insulin pathways. rictorΔ2 flies had smaller epidermal (leg and wing) and ommatidial cells and Mnt1 flies had larger cells in these tissues than the controls. Females had consistently larger cells than males in the three tissue types. In contrast, dorsal longitudinal flight muscle cells (measured only in males) were not altered by mutations. We suggest that mutations in cell cycle control pathways drive the evolution of systemic changes in cell size throughout the body, but additional mechanisms shape the cellular composition of some tissues independent of these mutations.
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Affiliation(s)
- Valeriya Privalova
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland
| | - Anna Maria Labecka
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland
| | - Ewa Szlachcic
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland
| | - Anna Sikorska
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland
| | - Marcin Czarnoleski
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387, Kraków, Poland.
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Szlachcic E, Labecka AM, Privalova V, Sikorska A, Czarnoleski M. Systemic orchestration of cell size throughout the body: influence of sex and rapamycin exposure in Drosophila melanogaster. Biol Lett 2023; 19:20220611. [PMID: 36946132 PMCID: PMC10031402 DOI: 10.1098/rsbl.2022.0611] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023] Open
Abstract
Along with differences in life histories, metazoans have also evolved vast differences in cellularity, involving changes in the molecular pathways controlling the cell cycle. The extent to which the signalling network systemically determines cellular composition throughout the body and whether tissue cellularity is organized locally to match tissue-specific functions are unclear. We cultured genetic lines of Drosophila melanogaster on food with and without rapamycin to manipulate the activity of target of rapamycin (TOR)/insulin pathways and evaluate cell-size changes in five types of adult cells: wing and leg epidermal cells, ommatidial cells, indirect flight muscle cells and Malpighian tubule epithelial cells. Rapamycin blocks TOR multiprotein complex 1, reducing cell growth, but this effect has been studied in single cell types. As adults, rapamycin-treated flies had smaller bodies and consistently smaller cells in all tissues. Regardless, females eclosed with larger bodies and larger cells in all tissues than males. Thus, differences in TOR activity and sex were associated with the orchestration of cell size throughout the body, leading to differences in body size. We postulate that the activity of TOR/insulin pathways and their effects on cellularity should be considered when investigating the origin of ecological and evolutionary patterns in life histories.
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Affiliation(s)
- Ewa Szlachcic
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland
| | - Anna Maria Labecka
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland
| | - Valeriya Privalova
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland
| | - Anna Sikorska
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland
| | - Marcin Czarnoleski
- Life History Evolution Group, Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland
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Thermal and Oxygen Flight Sensitivity in Ageing Drosophila melanogaster Flies: Links to Rapamycin-Induced Cell Size Changes. BIOLOGY 2021; 10:biology10090861. [PMID: 34571738 PMCID: PMC8464818 DOI: 10.3390/biology10090861] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/29/2021] [Accepted: 08/31/2021] [Indexed: 12/03/2022]
Abstract
Simple Summary Cold-blooded organisms can become physiologically challenged when performing highly oxygen-demanding activities (e.g., flight) across different thermal and oxygen environmental conditions. We explored whether this challenge decreases if an organism is built of smaller cells. This is because small cells create a large cell surface, which is costly, but can ease the delivery of oxygen to cells’ power plants, called mitochondria. We developed fruit flies in either standard food or food with rapamycin (a human drug altering the cell cycle and ageing), which produced flies with either large cells (no supplementation) or small cells (rapamycin supplementation). We measured the maximum speed at which flies were flapping their wings in warm and hot conditions, combined with either normal or reduced air oxygen concentrations. Flight intensity increased with temperature, and it was reduced by poor oxygen conditions, indicating limitations of flying insects by oxygen supply. Nevertheless, flies with small cells showed lower limitations, only slowing down their wing flapping in low oxygen in the hot environment. Our study suggests that small cells in a body can help cold-blooded organisms maintain demanding activities (e.g., flight), even in poor oxygen conditions, but this advantage can depend on body temperature. Abstract Ectotherms can become physiologically challenged when performing oxygen-demanding activities (e.g., flight) across differing environmental conditions, specifically temperature and oxygen levels. Achieving a balance between oxygen supply and demand can also depend on the cellular composition of organs, which either evolves or changes plastically in nature; however, this hypothesis has rarely been examined, especially in tracheated flying insects. The relatively large cell membrane area of small cells should increase the rates of oxygen and nutrient fluxes in cells; however, it does also increase the costs of cell membrane maintenance. To address the effects of cell size on flying insects, we measured the wing-beat frequency in two cell-size phenotypes of Drosophila melanogaster when flies were exposed to two temperatures (warm/hot) combined with two oxygen conditions (normoxia/hypoxia). The cell-size phenotypes were induced by rearing 15 isolines on either standard food (large cells) or rapamycin-enriched food (small cells). Rapamycin supplementation (downregulation of TOR activity) produced smaller flies with smaller wing epidermal cells. Flies generally flapped their wings at a slower rate in cooler (warm treatment) and less-oxygenated (hypoxia) conditions, but the small-cell-phenotype flies were less prone to oxygen limitation than the large-cell-phenotype flies and did not respond to the different oxygen conditions under the warm treatment. We suggest that ectotherms with small-cell life strategies can maintain physiologically demanding activities (e.g., flight) when challenged by oxygen-poor conditions, but this advantage may depend on the correspondence among body temperatures, acclimation temperatures and physiological thermal limits.
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