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Lirakis M, Nolte V, Schlötterer C. Pool-GWAS on reproductive dormancy in Drosophila simulans suggests a polygenic architecture. G3 GENES|GENOMES|GENETICS 2022; 12:6523974. [PMID: 35137042 PMCID: PMC8895979 DOI: 10.1093/g3journal/jkac027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 12/29/2021] [Indexed: 11/29/2022]
Abstract
The genetic basis of adaptation to different environments has been of long-standing interest to evolutionary biologists. Dormancy is a well-studied adaptation to facilitate overwintering. In Drosophila melanogaster, a moderate number of genes with large effects have been described, which suggests a simple genetic basis of dormancy. On the other hand, genome-wide scans for dormancy suggest a polygenic architecture in insects. In D. melanogaster, the analysis of the genetic architecture of dormancy is complicated by the presence of cosmopolitan inversions. Here, we performed a genome-wide scan to characterize the genetic basis of this ecologically extremely important trait in the sibling species of D. melanogaster, D. simulans that lacks cosmopolitan inversions. We performed Pool-GWAS in a South African D. simulans population for dormancy incidence at 2 temperature regimes (10 and 12°C, LD 10:14). We identified several genes with SNPs that showed a significant association with dormancy (P-value < 1e-13), but the overall modest response suggests that dormancy is a polygenic trait with many loci of small effect. Our results shed light on controversies on reproductive dormancy in Drosophila and have important implications for the characterization of the genetic basis of this trait.
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Affiliation(s)
- Manolis Lirakis
- Institut für Populationsgenetik, Vetmeduni Vienna, 1210 Wien, Austria
- Vienna Graduate School of Population Genetics, Vetmeduni Vienna, 1210 Wien, Austria
| | - Viola Nolte
- Institut für Populationsgenetik, Vetmeduni Vienna, 1210 Wien, Austria
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2
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Dobler R, Charette M, Kaplan K, Turnell BR, Reinhardt K. Divergent natural selection alters male sperm competition success in
Drosophila melanogaster. Ecol Evol 2022; 12:e8567. [PMID: 35222953 PMCID: PMC8848461 DOI: 10.1002/ece3.8567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Revised: 12/18/2021] [Accepted: 12/30/2021] [Indexed: 11/20/2022] Open
Abstract
Sexually selected traits may also be subject to non‐sexual selection. If optimal trait values depend on environmental conditions, then “narrow sense” (i.e., non‐sexual) natural selection can lead to local adaptation, with fitness in a certain environment being highest among individuals selected under that environment. Such adaptation can, in turn, drive ecological speciation via sexual selection. To date, most research on the effect of narrow‐sense natural selection on sexually selected traits has focused on precopulatory measures like mating success. However, postcopulatory traits, such as sperm function, can also be under non‐sexual selection, and have the potential to contribute to population divergence between different environments. Here, we investigate the effects of narrow‐sense natural selection on male postcopulatory success in Drosophila melanogaster. We chose two extreme environments, low oxygen (10%, hypoxic) or high CO2 (5%, hypercapnic) to detect small effects. We measured the sperm defensive (P1) and offensive (P2) capabilities of selected and control males in the corresponding selection environment and under control conditions. Overall, selection under hypoxia decreased both P1 and P2, while selection under hypercapnia had no effect. Surprisingly, P1 for both selected and control males was higher under both ambient hypoxia and ambient hypercapnia, compared to control conditions, while P2 was lower under hypoxia. We found limited evidence for local adaptation: the positive environmental effect of hypoxia on P1 was greater in hypoxia‐selected males than in controls. We discuss the implications of our findings for the evolution of postcopulatory traits in response to non‐sexual and sexual selection.
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Affiliation(s)
- Ralph Dobler
- Animal Evolutionary Ecology Institute of Evolution and Ecology Eberhard Karls University of Tubingen Tübingen Germany
- Applied Zoology Institute of Zoology Technische Universität Dresden Dresden Germany
| | - Marc Charette
- Department of Biology University of Ottawa Ottawa Ontario Canada
| | - Katrin Kaplan
- Animal Evolutionary Ecology Institute of Evolution and Ecology Eberhard Karls University of Tubingen Tübingen Germany
| | - Biz R. Turnell
- Applied Zoology Institute of Zoology Technische Universität Dresden Dresden Germany
| | - Klaus Reinhardt
- Animal Evolutionary Ecology Institute of Evolution and Ecology Eberhard Karls University of Tubingen Tübingen Germany
- Applied Zoology Institute of Zoology Technische Universität Dresden Dresden Germany
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3
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Baleba SBS. Water immersion tolerance by larval instars of stable fly, Stomoxys calcitrans, L1758 (Diptera: Muscidae) impairs the fitness performance of their subsequent stages. BMC Ecol Evol 2021; 21:78. [PMID: 33947327 PMCID: PMC8097882 DOI: 10.1186/s12862-021-01810-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 04/27/2021] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND In holometabolous insects, environmental factors experienced in pre-imaginal life stages affect the life-history traits within that stage and can also influence subsequent life stages. Here, I assessed tolerance to water immersion by the larval instars of the stable fly, Stomoxys calcitrans L. (Diptera: Muscidae) and its impact on the life-history traits of their subsequent life stages. RESULTS After submerging the three larval instars of S. calcitrans in distilled water, I found that the first instar larvae remained active for longer as compared to the second and third instar larvae. Also, the first instar larvae took a longer period to recover from the stress-induced immobility when removed from the water and returned to ambient temperature. When I followed the development of individuals of each larval instar that survived from water immersion, I found that their developmental time, weight, pupation percentage, adult emergence percentage and adult weight were negatively affected by this stressor. However, the weight of S. calcitrans adults developed from immersed first larval instar individuals was not affected by water immersion whereas their counterparts developed from immersed second and third larval instars had lower body weight. This suggests that in S. calcitrans, water immersion stress at the earlier stage is less detrimental than that experienced at late stages. CONCLUSION This study provides a comparative overview of the fitness consequences associated with water immersion stress during S. calcitrans larval ontogeny. The results prove that the fitness shift induced by water immersion in S. calcitrans is stage-specific. My results illustrate the importance of considering each larval instar when assessing the impact of environmental factors on holometabolous insect performance as these may be decoupled by metamorphosis.
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Affiliation(s)
- Steve B S Baleba
- International Centre of Insect Physiology and Ecology (icipe), P.O. Box 30772-00100, Nairobi, Kenya.
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, 07745, Jena, Germany.
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4
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Harrison JF, Waters JS, Biddulph TA, Kovacevic A, Klok CJ, Socha JJ. Developmental plasticity and stability in the tracheal networks supplying Drosophila flight muscle in response to rearing oxygen level. JOURNAL OF INSECT PHYSIOLOGY 2018; 106:189-198. [PMID: 28927826 DOI: 10.1016/j.jinsphys.2017.09.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 08/16/2017] [Accepted: 09/09/2017] [Indexed: 06/07/2023]
Abstract
While it is clear that the insect tracheal system can respond in a compensatory manner to both hypoxia and hyperoxia, there is substantial variation in how different parts of the system respond. However, the response of tracheal structures, from the tracheoles to the largest tracheal trunks, have not been studied within one species. In this study, we examined the effect of larval/pupal rearing in hypoxia, normoxia, and hyperoxia (10, 21 or 40kPa oxygen) on body size and the tracheal supply to the flight muscles of Drosophila melanogaster, using synchrotron radiation micro-computed tomography (SR-µCT) to assess flight muscle volumes and the major tracheal trunks, and confocal microscopy to assess the tracheoles. Hypoxic rearing decreased thorax length whereas hyperoxic-rearing decreased flight muscle volumes, suggestive of negative effects of both extremes. Tomography at the broad organismal scale revealed no evidence for enlargement of the major tracheae in response to lower rearing oxygen levels, although tracheal size scaled with muscle volume. However, using confocal imaging, we found a strong inverse relationship between tracheole density within the flight muscles and rearing oxygen level, and shorter tracheolar branch lengths in hypoxic-reared animals. Although prior studies of larger tracheae in other insects indicate that axial diffusing capacity should be constant with sequential generations of branching, this pattern was not found in the fine tracheolar networks, perhaps due to the increasing importance of radial diffusion in this regime. Overall, D. melanogaster responded to rearing oxygen level with compensatory morphological changes in the small tracheae and tracheoles, but retained stability in most of the other structural components of the tracheal supply to the flight muscles.
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Affiliation(s)
- Jon F Harrison
- School of Life Sciences, Arizona State University, PO Box 874501, Tempe, AZ 85287-4501, USA.
| | - James S Waters
- School of Life Sciences, Arizona State University, PO Box 874501, Tempe, AZ 85287-4501, USA; Department of Biology, Providence College, Providence, RI 02918, USA
| | - Taylor A Biddulph
- School of Life Sciences, Arizona State University, PO Box 874501, Tempe, AZ 85287-4501, USA
| | - Aleksandra Kovacevic
- School of Life Sciences, Arizona State University, PO Box 874501, Tempe, AZ 85287-4501, USA; School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - C Jaco Klok
- School of Life Sciences, Arizona State University, PO Box 874501, Tempe, AZ 85287-4501, USA; Sable Systems International, 3840 N. Commerce St., North Las Vegas, NV 89032, USA
| | - John J Socha
- Department of Biomedical Engineering and Mechanics, Virginia Tech, 332 Norris Hall, Blacksburg, VA 24061, USA
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5
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VandenBrooks JM, Gstrein G, Harmon J, Friedman J, Olsen M, Ward A, Parker G. Supply and demand: How does variation in atmospheric oxygen during development affect insect tracheal and mitochondrial networks? JOURNAL OF INSECT PHYSIOLOGY 2018; 106:217-223. [PMID: 29122550 DOI: 10.1016/j.jinsphys.2017.11.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 10/24/2017] [Accepted: 11/06/2017] [Indexed: 06/07/2023]
Abstract
Atmospheric oxygen is one of the most important atmospheric component for all terrestrial organisms. Variation in atmospheric oxygen has wide ranging effects on animal physiology, development, and evolution. This variation in oxygen has the potential to affect both respiratory systems (the supply side) and mitochondrial networks (the demand side) in animals. Insect respiratory systems supplying oxygen to tissues in the gas phase through blind ended tracheal systems are particularly susceptible to this variation. While the large conducting tracheae have previously been shown to respond developmentally to changes in rearing oxygen, the effect of oxygen on the tracheolar network has been relatively unexplored, especially in adult insects. Similarly, mitochondrial networks that meet energy demand in insects and other animals are dynamic and their enzyme activities have been shown to vary in the presence of oxygen. These two systems together should be under selective pressure to meet the aerobic metabolic requirements of insects. To test this hypothesis, we reared Mito-YFP Drosophila under three different oxygen concentrations hypoxia (12%), normoxia (21%), and hyperoxia (31%) and imaged their tracheolar and mitochondrial networks within their flight muscle using confocal microscopy. In terms of oxygen supply, hypoxia increased mean (mid-length) tracheolar diameters, tracheolar tip diameters, the number of tracheoles per main branch and affected tracheal branching patterns, while the opposite was observed in hyperoxia. In terms of oxygen demand, hypoxia increased mitochondrial investment and mitochondrial to tracheolar volume ratios; while the opposite was observed in hyperoxia. Generally, hypoxia had a stronger effect on both systems than hyperoxia. These results show that insects are capable of developmentally changing investment in both their supply and demand networks to increase overall fitness.
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Affiliation(s)
| | - Gregory Gstrein
- College of Veterinary Medicine, Midwestern University, Glendale, AZ 85308, USA
| | - Jason Harmon
- Arizona College of Osteopathic Medicine, Midwestern University, Glendale, AZ 85308, USA
| | - Jessica Friedman
- College of Veterinary Medicine, Midwestern University, Glendale, AZ 85308, USA
| | - Matthew Olsen
- College of Veterinary Medicine, Midwestern University, Glendale, AZ 85308, USA
| | - Anna Ward
- College of Veterinary Medicine, Midwestern University, Glendale, AZ 85308, USA
| | - Gregory Parker
- Department of Physiology, Midwestern University, Glendale, AZ 85308, USA
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6
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Harrison JF, Greenlee KJ, Verberk WCEP. Functional Hypoxia in Insects: Definition, Assessment, and Consequences for Physiology, Ecology, and Evolution. ANNUAL REVIEW OF ENTOMOLOGY 2018; 63:303-325. [PMID: 28992421 DOI: 10.1146/annurev-ento-020117-043145] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Insects can experience functional hypoxia, a situation in which O2 supply is inadequate to meet oxygen demand. Assessing when functional hypoxia occurs is complex, because responses are graded, age and tissue dependent, and compensatory. Here, we compare information gained from metabolomics and transcriptional approaches and by manipulation of the partial pressure of oxygen. Functional hypoxia produces graded damage, including damaged macromolecules and inflammation. Insects respond by compensatory physiological and morphological changes in the tracheal system, metabolic reorganization, and suppression of activity, feeding, and growth. There is evidence for functional hypoxia in eggs, near the end of juvenile instars, and during molting. Functional hypoxia is more likely in species with lower O2 availability or transport capacities and when O2 need is great. Functional hypoxia occurs normally during insect development and is a factor in mediating life-history trade-offs.
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Affiliation(s)
- Jon F Harrison
- School of Life Sciences, Arizona State University, Tempe, Arizona 85287-4501;
| | - Kendra J Greenlee
- Department of Biological Sciences, North Dakota State University, Fargo, North Dakota 58108-6050;
| | - Wilco C E P Verberk
- Department of Animal Ecology and Ecophysiology, Radboud University, Nijmegen, Netherlands;
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7
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Dobler R, Reinhardt K. Heritability, evolvability, phenotypic plasticity and temporal variation in sperm-competition success of Drosophila melanogaster. J Evol Biol 2016; 29:929-41. [PMID: 26990919 DOI: 10.1111/jeb.12858] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 03/07/2016] [Accepted: 03/08/2016] [Indexed: 11/28/2022]
Abstract
Sperm-competition success (SCS) is seen as centrally important for evolutionary change: superior fathers sire superior sons and thereby inherit the traits that make them superior. Additional hypotheses, that phenotypic plasticity in SCS and sperm ageing explain variation in paternity, are less considered. Even though various alleles have individually been shown to be correlated with variation in SCS, few studies have addressed the heritability, or evolvability, of overall SCS. Those studies that have addressed found low or no heritability and have not examined evolvability. They have further not excluded phenotypic plasticity, and temporal effects on SCS, despite their known dramatic effects on sperm function. In Drosophila melanogaster, we found that both standard components of sperm competition, sperm defence and sperm offence, showed nonsignificant heritability across several offspring cohorts. Instead, our analysis revealed, for the first time, the existence of phenotypic plasticity in SCS across an extreme environment (5% CO2 ), and an influence of sperm ageing. Evolvability of SCS was substantial for sperm defence but weak for sperm offence. Our results suggest that the paradigm of explaining evolution by sperm competition is more complex and will benefit from further experimental work on the heritability or evolvability of SCS, measuring phenotypic plasticity, and separating the effects of sperm competition and sperm ageing.
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Affiliation(s)
- R Dobler
- Department of Biology, Applied Zoology, TU Dresden, Dresden, Germany.,University of Tübingen, Institute of Evolution and Ecology, Tübingen, Germany
| | - K Reinhardt
- Department of Biology, Applied Zoology, TU Dresden, Dresden, Germany.,University of Tübingen, Institute of Evolution and Ecology, Tübingen, Germany
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8
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Bosco G, Clamer M, Messulam E, Dare C, Yang Z, Zordan M, Reggiani C, Hu Q, Megighian A. Effects of oxygen concentration and pressure on Drosophila melanogaster: oxidative stress, mitochondrial activity, and survivorship. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2015; 88:222-234. [PMID: 25529352 DOI: 10.1002/arch.21217] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Organisms are known to be equipped with an adaptive plasticity as the phenotype of traits in response to the imposed environmental challenges as they grow and develop. In this study, the effects of extreme changes in oxygen availability and atmospheric pressure on physiological phenotypes of Drosophila melanogaster were investigated to explore adaptation mechanisms. The changes in citrate synthase activity (CSA), lifespan, and behavioral function in different atmospheric conditions were evaluated. In the CAS test, hyperoxia significantly increased CSA; both hypoxia and hyperbaric conditions caused a significant decrease in CSA. In the survivorship test, all changed atmospheric conditions caused a significant reduction in lifespan. The lifespan reduced more after hypoxia exposure than after hyperbaria exposure. In behavioral function test, when mechanical agitation was conducted, bang-sensitive flies showed a stereotypical sequence of initial muscle spasm, paralysis, and recovery. The percentage of individuals that displayed paralysis or seizure was measured on the following day and after 2 weeks from each exposure. The majority of flies showed seizure behavior 15 days after exposure, especially after 3 h of exposure. The percentage of individuals that did not undergo paralysis or seizure and was able to move in the vial, was also tested. The number of flies that moved and raised the higher level of the vial decreased after exposure. Animal's speed decreased significantly 15 days after exposure to extreme environmental conditions. In summary, the alteration of oxygen availability and atmospheric pressure may lead to significant changes in mitochondria mass, lifespan, and behavioral function in D. melanogaster.
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Affiliation(s)
- Gerardo Bosco
- Department of Biomedical Science, University of Padua, Padua, Italy; Hyperbaric Center Association Hyperbaric Technicians ATIP, Padua, Italy
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9
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Wang Y, Zuber R, Oehl K, Norum M, Moussian B. Report on D
rosophila melanogaster
larvae without functional tracheae. J Zool (1987) 2015. [DOI: 10.1111/jzo.12226] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Y. Wang
- Animal Genetics; Interfaculty Institute for Cell Biology; University of Tübingen; Tübingen Germany
| | - R. Zuber
- Animal Genetics; Interfaculty Institute for Cell Biology; University of Tübingen; Tübingen Germany
| | - K. Oehl
- Animal Genetics; Interfaculty Institute for Cell Biology; University of Tübingen; Tübingen Germany
| | - M. Norum
- Institute of Biomedicine; University of Göteborg; Göteborg Sweden
| | - B. Moussian
- Animal Genetics; Interfaculty Institute for Cell Biology; University of Tübingen; Tübingen Germany
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10
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Gershman SN, Toumishey E, Rundle HD. Time flies: Time of day and social environment affect cuticular hydrocarbon sexual displays in Drosophila serrata. Proc Biol Sci 2014; 281:20140821. [PMID: 25143030 PMCID: PMC4150315 DOI: 10.1098/rspb.2014.0821] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2014] [Accepted: 07/23/2014] [Indexed: 11/12/2022] Open
Abstract
Recent work on Drosophila cuticular hydrocarbons (CHCs) challenges a historical assumption that CHCs in flies are largely invariant. Here, we examine the effect of time of day and social environment on a suite of sexually selected CHCs in Drosophila serrata. We demonstrate that males become more attractive to females during the time of day that flies are most active and when most matings occur, but females become less attractive to males during the same time of day. These opposing temporal changes may reflect differences in selection among the sexes. To evaluate the effect of social environment on male CHC attractiveness, we manipulated male opportunity for mating: male flies were housed either alone, with five females, with five males or with five males and five females. We found that males had the most attractive CHCs when with females, and less attractive CHCs when with competitor males. Social environment mediated how male CHC attractiveness cycled: males housed with females and/or other males showed temporal changes in CHC attractiveness, whereas males housed alone did not. In total, our results demonstrate temporal patterning of male CHCs that is dependent on social environment, and suggest that such changes may be beneficial to males.
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Affiliation(s)
- Susan N Gershman
- Department of Biology, University of Ottawa, 30 Marie-Curie Priv., Ottawa, Ontario, Canada K1N 6N5 Department of Evolution, Ecology and Organismal Biology, The Ohio State University at Marion, 1465 Mount Vernon Avenue, Marion, OH 43302, USA
| | - Ethan Toumishey
- Department of Biology, University of Ottawa, 30 Marie-Curie Priv., Ottawa, Ontario, Canada K1N 6N5
| | - Howard D Rundle
- Department of Biology, University of Ottawa, 30 Marie-Curie Priv., Ottawa, Ontario, Canada K1N 6N5
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11
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Milton SL, Dawson-Scully K. Alleviating brain stress: what alternative animal models have revealed about therapeutic targets for hypoxia and anoxia. FUTURE NEUROLOGY 2013; 8:287-301. [PMID: 25264428 DOI: 10.2217/fnl.13.12] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
While the mammalian brain is highly dependent on oxygen, and can withstand only a few minutes without air, there are both vertebrate and invertebrate examples of anoxia tolerance. One example is the freshwater turtle, which can withstand days without oxygen, thus providing a vertebrate model with which to examine the physiology of anoxia tolerance without the pathology seen in mammalian ischemia/reperfusion studies. Insect models such as Drosophila melanogaster have additional advantages, such as short lifespans, low cost and well-described genetics. These models of anoxia tolerance share two common themes that enable survival without oxygen: entrance into a state of deep hypometabolism, and the suppression of cellular injury during anoxia and upon restoration of oxygen. The study of such models of anoxia tolerance, adapted through millions of years of evolution, may thus suggest protective pathways that could serve as therapeutic targets for diseases characterized by oxygen deprivation and ischemic/reperfusion injuries.
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Affiliation(s)
- Sarah L Milton
- Department of Biological Sciences, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431, USA
| | - Ken Dawson-Scully
- Department of Biological Sciences, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431, USA
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12
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Harrison JF, Cease AJ, Vandenbrooks JM, Albert T, Davidowitz G. Caterpillars selected for large body size and short development time are more susceptible to oxygen-related stress. Ecol Evol 2013; 3:1305-16. [PMID: 23762517 PMCID: PMC3678485 DOI: 10.1002/ece3.551] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 02/25/2013] [Accepted: 02/28/2013] [Indexed: 12/03/2022] Open
Abstract
Recent studies suggest that higher growth rates may be associated with reduced capacities for stress tolerance and increased accumulated damage due to reactive oxygen species. We tested the response of Manduca sexta (Sphingidae) lines selected for large or small body size and short development time to hypoxia (10 kPa) and hyperoxia (25, 33, and 40 kPa); both hypoxia and hyperoxia reduce reproduction and oxygen levels over 33 kPa have been shown to increase oxidative damage in insects. Under normoxic (21 kPa) conditions, individuals from the large-selected (big-fast) line were larger and had faster growth rates, slightly longer developmental times, and reduced survival rates compared to individuals from a line selected for small size (small-fast) or an unselected control line. Individuals from the big-fast line exhibited greater negative responses to hyperoxia with greater reductions in juvenile and adult mass, growth rate, and survival than the other two lines. Hypoxia generally negatively affected survival and growth/size, but the lines responded similarly. These results are mostly consistent with the hypothesis that simultaneous acquisition of large body sizes and short development times leads to reduced capacities for coping with stressful conditions including oxidative damage. This result is of particular importance in that natural selection tends to decrease development time and increase body size.
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Affiliation(s)
- Jon F Harrison
- School of Life Sciences, Arizona State University Tempe, Arizona, 85287-4501
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