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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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2
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Bury S, Kratochvíl L, Starostová Z. Scaling of erythrocyte shape and nucleus size among squamate reptiles: reanalysis points to constrained, proportional rather than adaptive changes. ROYAL SOCIETY OPEN SCIENCE 2023; 10:221513. [PMID: 37122952 PMCID: PMC10130710 DOI: 10.1098/rsos.221513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 04/04/2023] [Indexed: 05/03/2023]
Abstract
Small erythrocytes might be beneficial for blood rheology, as they contribute less to blood viscosity than large erythrocytes. We predicted that rheological disadvantages of larger erythrocytes could be alleviated by relatively smaller nucleus size in larger cells allowing higher flexibility and by more elongated shape. Across squamate reptiles, we found that species with larger erythrocytes tend to have smaller ratio of nucleus size to cell size (N : C ratio), but that larger erythrocytes tend to be rounder, not more elongated. Nevertheless, we document that in fact nucleus area changes with erythrocyte area more or less linearly, which is also true for the relationship between cell length and cell width. These linear relationships suggest that nucleus size and cell size, and cell width and cell length, might be constrained to largely proportional mutual changes. The shifts in widely used N : C ratio and elongation ratio (cell length/cell width) with cell size might be misleading, as they do not reflect adaptive or maladaptive changes of erythrocytes, but rather mathematically trivial scaling of the ratios of two variables with a linear relationship with non-zero intercepts. We warn that ratio scaling without analyses of underlying patterns of evolutionary changes can lead to misinterpretation of evolutionary processes.
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Affiliation(s)
- Stanisław Bury
- Department of Comparative Anatomy, Institute of Zoology and Biomedical Research, Jagiellonian University, Gronostajowa 9, 30-387 Kraków, Poland
| | - Lukáš Kratochvíl
- Department of Ecology, Faculty of Science, Charles University, Viničná 7, 12844 Prague, Czech Republic
| | - Zuzana Starostová
- Department of Zoology, Faculty of Science, Charles University, Viničná 7, 12844 Prague, Czech Republic
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3
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van de Pol ILE, Hermaniuk A, Verberk WCEP. Interacting Effects of Cell Size and Temperature on Gene Expression, Growth, Development and Swimming Performance in Larval Zebrafish. Front Physiol 2021; 12:738804. [PMID: 34950046 PMCID: PMC8691434 DOI: 10.3389/fphys.2021.738804] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 11/12/2021] [Indexed: 11/13/2022] Open
Abstract
Cell size may be important in understanding the thermal biology of ectotherms, as the regulation and consequences of cell size appear to be temperature dependent. Using a recently developed model system of triploid zebrafish (which have around 1.5-fold larger cells than their diploid counterparts) we examine the effects of cell size on gene expression, growth, development and swimming performance in zebrafish larvae at different temperatures. Both temperature and ploidy affected the expression of genes related to metabolic processes (citrate synthase and lactate dehydrogenase), growth and swimming performance. Temperature also increased development rate, but there was no effect of ploidy level. We did find interactive effects between ploidy and temperature for gene expression, body size and swimming performance, confirming that the consequences of cell size are temperature dependent. Triploids with larger cells performed best at cool conditions, while diploids performed better at warmer conditions. These results suggest different selection pressures on ectotherms and their cell size in cold and warm habitats.
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Affiliation(s)
- Iris Louise Eleonora van de Pol
- Department of Animal Ecology and Physiology, Radboud Institute for Biological and Environmental Sciences, Radboud University, Nijmegen, Netherlands
| | - Adam Hermaniuk
- Department of Evolutionary and Physiological Ecology, Faculty of Biology, University of Białystok, Białystok, 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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Glazier DS. Genome Size Covaries More Positively with Propagule Size than Adult Size: New Insights into an Old Problem. BIOLOGY 2021; 10:270. [PMID: 33810583 PMCID: PMC8067107 DOI: 10.3390/biology10040270] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 03/18/2021] [Accepted: 03/23/2021] [Indexed: 12/17/2022]
Abstract
The body size and (or) complexity of organisms is not uniformly related to the amount of genetic material (DNA) contained in each of their cell nuclei ('genome size'). This surprising mismatch between the physical structure of organisms and their underlying genetic information appears to relate to variable accumulation of repetitive DNA sequences, but why this variation has evolved is little understood. Here, I show that genome size correlates more positively with egg size than adult size in crustaceans. I explain this and comparable patterns observed in other kinds of animals and plants as resulting from genome size relating strongly to cell size in most organisms, which should also apply to single-celled eggs and other reproductive propagules with relatively few cells that are pivotal first steps in their lives. However, since body size results from growth in cell size or number or both, it relates to genome size in diverse ways. Relationships between genome size and body size should be especially weak in large organisms whose size relates more to cell multiplication than to cell enlargement, as is generally observed. The ubiquitous single-cell 'bottleneck' of life cycles may affect both genome size and composition, and via both informational (genotypic) and non-informational (nucleotypic) effects, many other properties of multicellular organisms (e.g., rates of growth and metabolism) that have both theoretical and practical significance.
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6
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Verberk WC, Atkinson D, Hoefnagel KN, Hirst AG, Horne CR, Siepel H. Shrinking body sizes in response to warming: explanations for the temperature-size rule with special emphasis on the role of oxygen. Biol Rev Camb Philos Soc 2021; 96:247-268. [PMID: 32959989 PMCID: PMC7821163 DOI: 10.1111/brv.12653] [Citation(s) in RCA: 99] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 08/28/2020] [Accepted: 08/28/2020] [Indexed: 01/04/2023]
Abstract
Body size is central to ecology at levels ranging from organismal fecundity to the functioning of communities and ecosystems. Understanding temperature-induced variations in body size is therefore of fundamental and applied interest, yet thermal responses of body size remain poorly understood. Temperature-size (T-S) responses tend to be negative (e.g. smaller body size at maturity when reared under warmer conditions), which has been termed the temperature-size rule (TSR). Explanations emphasize either physiological mechanisms (e.g. limitation of oxygen or other resources and temperature-dependent resource allocation) or the adaptive value of either a large body size (e.g. to increase fecundity) or a short development time (e.g. in response to increased mortality in warm conditions). Oxygen limitation could act as a proximate factor, but we suggest it more likely constitutes a selective pressure to reduce body size in the warm: risks of oxygen limitation will be reduced as a consequence of evolution eliminating genotypes more prone to oxygen limitation. Thus, T-S responses can be explained by the 'Ghost of Oxygen-limitation Past', whereby the resulting (evolved) T-S responses safeguard sufficient oxygen provisioning under warmer conditions, reflecting the balance between oxygen supply and demands experienced by ancestors. T-S responses vary considerably across species, but some of this variation is predictable. Body-size reductions with warming are stronger in aquatic taxa than in terrestrial taxa. We discuss whether larger aquatic taxa may especially face greater risks of oxygen limitation as they grow, which may be manifested at the cellular level, the level of the gills and the whole-organism level. In contrast to aquatic species, terrestrial ectotherms may be less prone to oxygen limitation and prioritize early maturity over large size, likely because overwintering is more challenging, with concomitant stronger end-of season time constraints. Mechanisms related to time constraints and oxygen limitation are not mutually exclusive explanations for the TSR. Rather, these and other mechanisms may operate in tandem. But their relative importance may vary depending on the ecology and physiology of the species in question, explaining not only the general tendency of negative T-S responses but also variation in T-S responses among animals differing in mode of respiration (e.g. water breathers versus air breathers), genome size, voltinism and thermally associated behaviour (e.g. heliotherms).
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Affiliation(s)
- Wilco C.E.P. Verberk
- Department of Animal Ecology and Physiology, Institute for Water and Wetland ResearchRadboud UniversityHeyendaalseweg 1356525 AJNijmegenThe Netherlands
| | - David Atkinson
- Department of Evolution, Ecology and BehaviourUniversity of LiverpoolLiverpoolL69 7ZBU.K.
| | - K. Natan Hoefnagel
- Department of Animal Ecology and Physiology, Institute for Water and Wetland ResearchRadboud UniversityHeyendaalseweg 1356525 AJNijmegenThe Netherlands
- Faculty of Science and Engineering, Ocean Ecosystems — Energy and Sustainability Research Institute GroningenUniversity of GroningenNijenborgh 79747 AGGroningenThe Netherlands
| | - Andrew G. Hirst
- School of Environmental SciencesUniversity of LiverpoolLiverpoolL69 3GPU.K.
- Centre for Ocean Life, DTU AquaTechnical University of DenmarkLyngbyDenmark
| | - Curtis R. Horne
- School of Environmental SciencesUniversity of LiverpoolLiverpoolL69 3GPU.K.
| | - Henk Siepel
- Department of Animal Ecology and Physiology, Institute for Water and Wetland ResearchRadboud UniversityHeyendaalseweg 1356525 AJNijmegenThe Netherlands
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Hermaniuk A, van de Pol ILE, Verberk WCEP. Are acute and acclimated thermal effects on metabolic rate modulated by cell size? A comparison between diploid and triploid zebrafish larvae. J Exp Biol 2021; 224:jeb227124. [PMID: 33257437 DOI: 10.1242/jeb.227124] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 11/19/2020] [Indexed: 12/13/2022]
Abstract
Being composed of small cells may carry energetic costs related to maintaining ionic gradients across cell membranes as well as benefits related to diffusive oxygen uptake. Here, we test the hypothesis that these costs and benefits of cell size in ectotherms are temperature dependent. To study the consequences of cell size for whole-organism metabolic rate, we compared diploid and triploid zebrafish larvae differing in cell size. A fully factorial design was applied combining three different rearing and test temperatures that allowed us to distinguish acute from acclimated thermal effects. Individual oxygen consumption rates of diploid and triploid larvae across declining levels of oxygen availability were measured. We found that both acute and acclimated thermal effects affected the metabolic response. In comparison with triploids, diploids responded more strongly to acute temperatures, especially when reared at the highest temperature. These observations support the hypothesis that animals composed of smaller cells (i.e. diploids) are less vulnerable to oxygen limitation in warm aquatic habitats. Furthermore, we found slightly improved hypoxia tolerance in diploids. By contrast, warm-reared triploids had higher metabolic rates when they were tested at acute cold temperature, suggesting that being composed of larger cells may provide metabolic advantages in the cold. We offer two mechanisms as a potential explanation of this result, related to homeoviscous adaptation of membrane function and the mitigation of developmental noise. Our results suggest that being composed of larger cells provides metabolic advantages in cold water, while being composed of smaller cells provides metabolic advantages in warm water.
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Affiliation(s)
- Adam Hermaniuk
- Department of Evolutionary and Physiological Ecology, Faculty of Biology, University of Białystok, Ciołkowskiego 1J, 15-245 Białystok, Poland
| | - Iris L E van de Pol
- Department of Animal Ecology and Physiology, Institute for Water and Wetland Research, Radboud University, 6525 AJ Nijmegen, The Netherlands
| | - Wilco C E P Verberk
- Department of Animal Ecology and Physiology, Institute for Water and Wetland Research, Radboud University, 6525 AJ Nijmegen, The Netherlands
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Antoł A, Labecka AM, Horváthová T, Sikorska A, Szabla N, Bauchinger U, Kozłowski J, Czarnoleski M. Effects of thermal and oxygen conditions during development on cell size in the common rough woodlice Porcellio scaber. Ecol Evol 2020; 10:9552-9566. [PMID: 32953083 PMCID: PMC7487255 DOI: 10.1002/ece3.6683] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 07/10/2020] [Accepted: 07/27/2020] [Indexed: 01/18/2023] Open
Abstract
During development, cells may adjust their size to balance between the tissue metabolic demand and the oxygen and resource supply: Small cells may effectively absorb oxygen and nutrients, but the relatively large area of the plasma membrane requires costly maintenance. Consequently, warm and hypoxic environments should favor ectotherms with small cells to meet increased metabolic demand by oxygen supply. To test these predictions, we compared cell size (hindgut epithelium, hepatopancreas B cells, ommatidia) in common rough woodlice (Porcellio scaber) that were developed under four developmental conditions designated by two temperatures (15 or 22°C) and two air O2 concentrations (10% or 22%). To test whether small-cell woodlice cope better under increased metabolic demand, the CO2 production of each woodlouse was measured under cold, normoxic conditions and under warm, hypoxic conditions, and the magnitude of metabolic increase (MMI) was calculated. Cell sizes were highly intercorrelated, indicative of organism-wide mechanisms of cell cycle control. Cell size differences among woodlice were largely linked with body size changes (larger cells in larger woodlice) and to a lesser degree with oxygen conditions (development of smaller cells under hypoxia), but not with temperature. Developmental conditions did not affect MMI, and contrary to predictions, large woodlice with large cells showed higher MMI than small woodlice with small cells. We also observed complex patterns of sexual difference in the size of hepatopancreatic cells and the size and number of ommatidia, which are indicative of sex differences in reproductive biology. We conclude that existing theories about the adaptiveness of cell size do not satisfactorily explain the patterns in cell size and metabolic performance observed here in P. scaber. Thus, future studies addressing physiological effects of cell size variance should simultaneously consider different organismal elements that can be involved in sustaining the metabolic demands of tissue, such as the characteristics of gas-exchange organs and O2-binding proteins.
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Affiliation(s)
- Andrzej Antoł
- Institute of Environmental SciencesJagiellonian UniversityKrakówPoland
| | | | - Terézia Horváthová
- Institute of Environmental SciencesJagiellonian UniversityKrakówPoland
- Institute of Soil BiologyBiology Centre CASČeské BudějoviceCzech Republic
| | - Anna Sikorska
- Institute of Environmental SciencesJagiellonian UniversityKrakówPoland
| | - Natalia Szabla
- Institute of Environmental SciencesJagiellonian UniversityKrakówPoland
| | - Ulf Bauchinger
- Institute of Environmental SciencesJagiellonian UniversityKrakówPoland
- Nencki Institute of Experimental BiologyPolish Academy of SciencesWarsawPoland
| | - Jan Kozłowski
- Institute of Environmental SciencesJagiellonian UniversityKrakówPoland
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9
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Li Q, Zhu X, Xiong W, Zhu Y, Zhang J, Djiba PK, Lv X, Luo Y. Effects of temperature on metabolic scaling in black carp. PeerJ 2020; 8:e9242. [PMID: 32518735 PMCID: PMC7261118 DOI: 10.7717/peerj.9242] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 05/05/2020] [Indexed: 01/23/2023] Open
Abstract
The surface area (SA) of organs and cells may vary with temperature, which changes the SA exchange limitation on metabolic flows as well as the influence of temperature on metabolic scaling. The effect of SA change can intensify (when the effect is the same as that of temperature) or compensate for (when the effect is the opposite of that of temperature) the negative effects of temperature on metabolic scaling, which can result in multiple patterns of metabolic scaling with temperature among species. The present study aimed to examine whether metabolic scaling in black carp changes with temperature and to identify the link between metabolic scaling and SA at the organ and cellular levels at different temperatures. The resting metabolic rate (RMR), gill surface area (GSA) and red blood cell (RBC) size of black carp with different body masses were measured at 10 °C and 25 °C, and the scaling exponents of these parameters were compared. The results showed that both body mass and temperature independently affected the RMR, GSA and RBC size of black carp. A consistent scaling exponent of RMR (0.764, 95% CI [0.718-0.809]) was obtained for both temperatures. The RMR at 25 °C was 2.7 times higher than that at 10 °C. At both temperatures, the GSA scaled consistently with body mass by an exponent of 0.802 (95% CI [0.759-0.846]), while RBC size scaled consistently with body mass by an exponent of 0.042 (95% CI [0.010-0.075]). The constant GSA scaling can explain the constant metabolic scaling as temperature increases, as metabolism may be constrained by fluxes across surfaces. The GSA at 10 °C was 1.2 times higher than that at 25 °C, which suggests that the constraints of GSA on the metabolism of black carp is induced by the higher temperature. The RBC size at 10 °C was 1.1 times higher than that at 25 °C. The smaller RBC size (a larger surface-to-volume ratio) at higher temperature suggests an enhanced oxygen supply and a reduced surface boundary limit on b R, which offset the negative effect of temperature on b R.
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Affiliation(s)
- Qian Li
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, School of Life Sciences, Southwest University, Chongqing, China
| | - Xiaoling Zhu
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, School of Life Sciences, Southwest University, Chongqing, China
| | - Wei Xiong
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, School of Life Sciences, Southwest University, Chongqing, China
| | - Yanqiu Zhu
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, School of Life Sciences, Southwest University, Chongqing, China
| | - Jianghui Zhang
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, School of Life Sciences, Southwest University, Chongqing, China
| | - Pathe Karim Djiba
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, School of Life Sciences, Southwest University, Chongqing, China
| | - Xiao Lv
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, School of Life Sciences, Southwest University, Chongqing, China
| | - Yiping Luo
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, School of Life Sciences, Southwest University, Chongqing, China
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van de Pol ILE, Flik G, Verberk WCEP. Triploidy in zebrafish larvae: Effects on gene expression, cell size and cell number, growth, development and swimming performance. PLoS One 2020; 15:e0229468. [PMID: 32119699 PMCID: PMC7051096 DOI: 10.1371/journal.pone.0229468] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 02/06/2020] [Indexed: 12/14/2022] Open
Abstract
There is renewed interest in the regulation and consequences of cell size adaptations in studies on understanding the ecophysiology of ectotherms. Here we test if induction of triploidy, which increases cell size in zebrafish (Danio rerio), makes for a good model system to study consequences of cell size. Ideally, diploid and triploid zebrafish should differ in cell size, but should otherwise be comparable in order to be suitable as a model. We induced triploidy by cold shock and compared diploid and triploid zebrafish larvae under standard rearing conditions for differences in genome size, cell size and cell number, development, growth and swimming performance and expression of housekeeping genes and hsp70.1. Triploid zebrafish have larger but fewer cells, and the increase in cell size matched the increase in genome size (+ 50%). Under standard conditions, patterns in gene expression, ontogenetic development and larval growth were near identical between triploids and diploids. However, under demanding conditions (i.e. the maximum swimming velocity during an escape response), triploid larvae performed poorer than their diploid counterparts, especially after repeated stimuli to induce swimming. This result is consistent with the idea that larger cells have less capacity to generate energy, which becomes manifest during repeated physical exertion resulting in increased fatigue. Triploidy induction in zebrafish appears a valid method to increase specifically cell size and this provides a model system to test for consequences of cell size adaptation for the energy budget and swimming performance of this ectothermic vertebrate.
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Affiliation(s)
- Iris L. E. van de Pol
- Department of Animal Ecology and Physiology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
- * E-mail:
| | - Gert Flik
- Department of Animal Ecology and Physiology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
| | - Wilco C. E. P. Verberk
- Department of Animal Ecology and Physiology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands
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11
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Bury S, Bury A, Sadowska ET, Cichoń M, Bauchinger U. More than just the numbers-contrasting response of snake erythrocytes to thermal acclimation. Naturwissenschaften 2019; 106:24. [PMID: 31069520 DOI: 10.1007/s00114-019-1617-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 01/29/2019] [Accepted: 04/11/2019] [Indexed: 11/29/2022]
Abstract
Acclimation to lower temperatures decreases energy expenditure in ectotherms but increases oxygen consumption in most endotherms, when dropped below thermoneutrality. Such differences should be met by adjustments in oxygen transport through blood. Changes in hematological variables in correspondence to that in metabolic rates are, however, not fully understood, particularly in non-avian reptiles. We investigated the effect of thermal acclimation on a snake model, the grass snakes (Natrix natrix). After 6 months of acclimation to either 18 °C or 32 °C hematocrit, hemoglobin concentration, erythrocyte number, and size were assessed. All variables revealed significantly lower values under warm compared to cold ambient temperature. Our data suggest that non-avian reptiles, similarly as birds, reduce erythrocyte fraction under energy-demanding temperatures. Due to low deformability of nucleated erythrocytes in sauropsids, such reduced fraction may be important in decreasing blood viscosity to optimize blood flow. Novel findings on flexible erythrocyte size provide an important contribution to this optimization process.
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Affiliation(s)
- Stanisław Bury
- Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387, Cracow, Poland.
| | - Agata Bury
- Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387, Cracow, Poland
| | - Edyta T Sadowska
- Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387, Cracow, Poland
| | - Mariusz Cichoń
- Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387, Cracow, Poland
| | - Ulf Bauchinger
- Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387, Cracow, Poland
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12
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Benfey TJ, Devlin RH. Ploidy Has Minimal Effect on Hypoxia Tolerance at High Temperature in Rainbow Trout (Oncorhynchus mykiss). Physiol Biochem Zool 2019; 91:1091-1101. [PMID: 30285539 DOI: 10.1086/700218] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Polyploidy is an important driver of evolutionary change (generally via tetraploidy) and also serves a practical role in aquaculture and fisheries management (via triploidy). Fundamental changes in cell size and number that accompany polyploidy are predicted to affect cellular and whole-animal physiology due to constraints placed on surface-mediated processes at the cellular level, potentially altering environmental tolerances and optima. The aim of this study was to determine whether the documented reduction in thermal tolerance of aquatic polyploids is a result of their being less hypoxia tolerant. This was assessed by holding diploid and triploid rainbow trout for 1 h above their thermal optima in separate trials at eight temperatures between 20° and 27°C and then rapidly reducing the oxygen tension (Po2) of the water and determining the nonlethal Po2 at which fish lost equilibrium. As expected, there was a highly significant ([Formula: see text]) effect of temperature on Po2 at loss of equilibrium. Although there was also a significant ([Formula: see text]) effect of ploidy on Po2 at loss of equilibrium, with triploid values higher than diploid, post hoc analyses showed no significant effect of ploidy at any specific temperature. Oxygen availability alone therefore does not appear to play a major role in determining the thermal tolerance of polyploids.
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Hermaniuk A, Rybacki M, Taylor JRE. Metabolic Rate of Diploid and Triploid Edible Frog Pelophylax esculentus Correlates Inversely with Cell Size in Tadpoles but Not in Frogs. Physiol Biochem Zool 2017; 90:230-239. [DOI: 10.1086/689408] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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