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Wilmsen SM, Dzialowski EM. Altering developmental oxygen exposure influences thermoregulation and flight performance of Manduca sexta. J Exp Biol 2024; 227:jeb247373. [PMID: 38873724 DOI: 10.1242/jeb.247373] [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: 01/22/2024] [Accepted: 05/08/2024] [Indexed: 06/15/2024]
Abstract
Endothermic, flying insects are capable of some of the highest recorded metabolic rates. This high aerobic demand is made possible by the insect's tracheal system, which supplies the flight muscles with oxygen. Many studies focus on metabolic responses to acute changes in oxygen to test the limits of the insect flight metabolic system, with some flying insects exhibiting oxygen limitation in flight metabolism. These acute studies do not account for possible changes induced by developmental phenotypic plasticity in response to chronic changes in oxygen levels. The endothermic moth Manduca sexta is a model organism that is easy to raise and exhibits a high thorax temperature during flight (∼40°C). In this study, we examined the effects of developmental oxygen exposure during the larval, pupal and adult stages on the adult moth's aerobic performance. We measured flight critical oxygen partial pressure (Pcrit-), thorax temperature and thermoregulating metabolic rate to understand the extent of developmental plasticity as well as effects of developmental oxygen levels on endothermic capacity. We found that developing in hypoxia (10% oxygen) decreased thermoregulating thorax temperature when compared with moths raised in normoxia or hyperoxia (30% oxygen), when moths were warming up in atmospheres with 21-30% oxygen. In addition, moths raised in hypoxia had lower critical oxygen levels when flying. These results suggest that chronic developmental exposure to hypoxia affects the adult metabolic phenotype and potentially has implications for thermoregulatory and flight behavior.
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Affiliation(s)
- Sara M Wilmsen
- Department of Biological Sciences, Advanced Environmental Research Institute, University of North Texas, Denton, TX 76201, USA
| | - Edward M Dzialowski
- Department of Biological Sciences, Advanced Environmental Research Institute, University of North Texas, Denton, TX 76201, USA
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2
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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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3
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Wilmsen SM, Dzialowski EM. Changes in growth and developmental timing in Manduca sexta when exposed to altered oxygen levels. ARTHROPOD STRUCTURE & DEVELOPMENT 2023; 72:101231. [PMID: 36571898 DOI: 10.1016/j.asd.2022.101231] [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: 09/06/2022] [Revised: 11/27/2022] [Accepted: 12/04/2022] [Indexed: 06/18/2023]
Abstract
The effect of chronic oxygen exposure on growth and development of insects is an active field of research. It seeks to unravel the triggers and limitations to molting and growth across many insect groups, although even now there are gaps in our knowledge and inconsistencies that need to be addressed. The oxygen dependent induction of molting (ODIM) hypothesis states that the impetus for molting is triggered by the development of hypoxic tissue due to the rapid increase in mass coupled with the fixed nature of tracheal systems between molts. In this study, we raised Manduca sexta in three chronic oxygen treatments (10, 21, & 30% O2). We measured the mass of these insects throughout their larval development and as adults. We found that both hyperoxia and hypoxia had marked effects on size and developmental times. Hyperoxia exposure resulted in increased mass throughout development and into adulthood while increasing developmental times. Hypoxia also increased developmental time and decreased mass of adult moths. We show that pupation is a critical window for exposure to altered oxygen levels. This suggests that oxygen may play a role in affecting the timing of eclosion at the end of pupation.
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Harrison JF, Biewener A, Bernhardt JR, Burger JR, Brown JH, Coto ZN, Duell ME, Lynch M, Moffett ER, Norin T, Pettersen AK, Smith FA, Somjee U, Traniello JFA, Williams TM. White Paper: An Integrated Perspective on the Causes of Hypometric Metabolic Scaling in Animals. Integr Comp Biol 2022; 62:icac136. [PMID: 35933126 PMCID: PMC9724154 DOI: 10.1093/icb/icac136] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Revised: 04/16/2022] [Accepted: 05/19/2022] [Indexed: 11/15/2022] Open
Abstract
Larger animals studied during ontogeny, across populations, or across species, usually have lower mass-specific metabolic rates than smaller animals (hypometric scaling). This pattern is usually observed regardless of physiological state (e.g. basal, resting, field, maximally-active). The scaling of metabolism is usually highly correlated with the scaling of many life history traits, behaviors, physiological variables, and cellular/molecular properties, making determination of the causation of this pattern challenging. For across-species comparisons of resting and locomoting animals (but less so for across populations or during ontogeny), the mechanisms at the physiological and cellular level are becoming clear. Lower mass-specific metabolic rates of larger species at rest are due to a) lower contents of expensive tissues (brains, liver, kidneys), and b) slower ion leak across membranes at least partially due to membrane composition, with lower ion pump ATPase activities. Lower mass-specific costs of larger species during locomotion are due to lower costs for lower-frequency muscle activity, with slower myosin and Ca++ ATPase activities, and likely more elastic energy storage. The evolutionary explanation(s) for hypometric scaling remain(s) highly controversial. One subset of evolutionary hypotheses relies on constraints on larger animals due to changes in geometry with size; for example, lower surface-to-volume ratios of exchange surfaces may constrain nutrient or heat exchange, or lower cross-sectional areas of muscles and tendons relative to body mass ratios would make larger animals more fragile without compensation. Another subset of hypotheses suggests that hypometric scaling arises from biotic interactions and correlated selection, with larger animals experiencing less selection for mass-specific growth or neurolocomotor performance. A additional third type of explanation comes from population genetics. Larger animals with their lower effective population sizes and subsequent less effective selection relative to drift may have more deleterious mutations, reducing maximal performance and metabolic rates. Resolving the evolutionary explanation for the hypometric scaling of metabolism and associated variables is a major challenge for organismal and evolutionary biology. To aid progress, we identify some variation in terminology use that has impeded cross-field conversations on scaling. We also suggest that promising directions for the field to move forward include: 1) studies examining the linkages between ontogenetic, population-level, and cross-species allometries, 2) studies linking scaling to ecological or phylogenetic context, 3) studies that consider multiple, possibly interacting hypotheses, and 4) obtaining better field data for metabolic rates and the life history correlates of metabolic rate such as lifespan, growth rate and reproduction.
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Affiliation(s)
- Jon F Harrison
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA
| | - Andrew Biewener
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Joanna R Bernhardt
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Yale Institute for Biospheric Studies, New Haven, CT 06520, USA
| | - Joseph R Burger
- Department of Biology, University of Kentucky, Lexington, KY 40506, USA
| | - James H Brown
- Center for Evolutionary and Theoretical Immunology, The University of New Mexico, Albuquerque, NM 87131, USA
| | - Zach N Coto
- Department of Biology, Boston University, Boston, MA 02215, USA
| | - Meghan E Duell
- Department of Biology, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Michael Lynch
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85281, USA
| | - Emma R Moffett
- Department of Ecology and Evolution, University of California, Irvine, CA 92697, USA
| | - Tommy Norin
- DTU Aqua | National Institute of Aquatic Resources, Technical University of Denmark, Anker Engelunds Vej 1 Bygning 101A, 2800 Kgs. Lyngby, Denmark
| | - Amanda K Pettersen
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW 2006, Australia
| | - Felisa A Smith
- Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Ummat Somjee
- Smithsonian Tropical Research Institute, Panama City, Panama
| | | | - Terrie M Williams
- Division of Physical and Biological Sciences, University of California, Santa Cruz, CA 95064, USA
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The steroid hormone ecdysone regulates growth rate in response to oxygen availability. Sci Rep 2022; 12:4730. [PMID: 35304878 PMCID: PMC8933497 DOI: 10.1038/s41598-022-08563-9] [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: 12/06/2021] [Accepted: 03/01/2022] [Indexed: 11/10/2022] Open
Abstract
In almost all animals, physiologically low oxygen (hypoxia) during development slows growth and reduces adult body size. The developmental mechanisms that determine growth under hypoxic conditions are, however, poorly understood. Here we show that the growth and body size response to moderate hypoxia (10% O2) in Drosophila melanogaster is systemically regulated via the steroid hormone ecdysone. Hypoxia increases level of circulating ecdysone and inhibition of ecdysone synthesis ameliorates the negative effect of low oxygen on growth. We also show that the effect of ecdysone on growth under hypoxia is through suppression of the insulin/IGF-signaling pathway, via increased expression of the insulin-binding protein Imp-L2. These data indicate that growth suppression in hypoxic Drosophila larvae is accomplished by a systemic endocrine mechanism that overlaps with the mechanism that slows growth at low nutrition. This suggests the existence of growth-regulatory mechanisms that respond to general environmental perturbation rather than individual environmental factors.
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Roberts KT, Rank NE, Dahlhoff EP, Stillman JH, Williams CM. Snow modulates winter energy use and cold exposure across an elevation gradient in a montane ectotherm. GLOBAL CHANGE BIOLOGY 2021; 27:6103-6116. [PMID: 34601792 DOI: 10.1111/gcb.15912] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 09/10/2021] [Accepted: 09/16/2021] [Indexed: 06/13/2023]
Abstract
Snow insulates the soil from air temperature, decreasing winter cold stress and altering energy use for organisms that overwinter in the soil. As climate change alters snowpack and air temperatures, it is critical to account for the role of snow in modulating vulnerability to winter climate change. Along elevational gradients in snowy mountains, snow cover increases but air temperature decreases, and it is unknown how these opposing gradients impact performance and fitness of organisms overwintering in the soil. We developed experimentally validated ecophysiological models of cold and energy stress over the past decade for the montane leaf beetle Chrysomela aeneicollis, along five replicated elevational transects in the Sierra Nevada mountains in California. Cold stress peaks at mid-elevations, while high elevations are buffered by persistent snow cover, even in dry years. While protective against cold, snow increases energy stress for overwintering beetles, particularly at low elevations, potentially leading to mortality or energetic tradeoffs. Declining snowpack will predominantly impact mid-elevation populations by increasing cold exposure, while high elevation habitats may provide refugia as drier winters become more common.
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Affiliation(s)
- Kevin T Roberts
- Department of Integrative Biology, University of California, Berkeley, California, USA
| | - Nathan E Rank
- Department of Biology, Sonoma State University, Rohnert Park, California, USA
| | | | - Jonathon H Stillman
- Department of Integrative Biology, University of California, Berkeley, California, USA
- Department of Biology, San Francisco State University, San Francisco, California, USA
| | - Caroline M Williams
- Department of Integrative Biology, University of California, Berkeley, California, USA
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VandenBrooks JM, Ford CF, Harrison JF. Responses to Alteration of Atmospheric Oxygen and Social Environment Suggest Trade-Offs among Growth Rate, Life Span, and Stress Susceptibility in Giant Mealworms ( Zophobas morio). Physiol Biochem Zool 2021; 93:358-368. [PMID: 32758057 DOI: 10.1086/710726] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Growth rate, development time, and response to environmental stressors vary tremendously across organisms, suggesting trade-offs that are affected by evolutionary or ecological factors, but such trade-offs are poorly understood. Prior studies using artificially selected lines of Manduca sexta suggest that insects with high growth rates, long development time, and large body size are more sensitive to hypoxic or hyperoxic stresses, such as reactive oxygen species (ROS) production, but the mechanisms and specific life-history associations remain unclear. Here, we manipulated the social environment to differentiate the effects of size, growth rate, and development time on oxygen sensitivity of the giant mealworm, Zophobas morio. Crowding reduced growth rates but yielded larger adults as a result of supernumerary molts and longer development times. The juvenile performance (growth rate, development time, adult mass) of crowd-reared mealworms was less sensitive to variation in atmospheric oxygen than it was for individually reared animals, consistent with the hypothesis that high growth rates are associated with increased sensitivity to ROS. Life span in normoxia was extended by crowd rearing, perhaps due to the larger size and/or increased resources of the larger adults. Life spans of crowd-reared animals were more negatively affected by hypoxia or hyperoxia than life spans of individually reared animals, possibly due to the longer total stress exposure of crowd-reared animals. These data suggest that animals with high growth rates experience a negative trade-off of performance with greater sensitivity to stress during the juvenile phase, while animals with long development times or life spans experience a negative trade-off of greater susceptibility of life span to environmental stress.
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He LL, Shin SH, Wang Z, Yuan I, Weschler R, Chiou A, Koyama T, Nijhout HF, Suzuki Y. Mechanism of threshold size assessment: Metamorphosis is triggered by the TGF-beta/Activin ligand Myoglianin. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2020; 126:103452. [PMID: 32822817 DOI: 10.1016/j.ibmb.2020.103452] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 08/02/2020] [Accepted: 08/02/2020] [Indexed: 06/11/2023]
Abstract
Although the mechanisms that control growth are now well understood, the mechanism by which animals assess their body size remains one of the great puzzles in biology. The final larval instar of holometabolous insects, after which growth stops and metamorphosis begins, is specified by a threshold size. We investigated the mechanism of threshold size assessment in the tobacco hornworm, Manduca sexta. The threshold size was found to change depending on the amount of exposure to poor nutrient conditions whereas hypoxia treatment consistently led to a lower threshold size. Under these various conditions, the mass of the muscles plus integuments was correlated with the threshold size. Furthermore, the expression of myoglianin (myo) increased at the threshold size in both M. sexta and Tribolium castaneum. Knockdown of myo in T. castaneum led to larvae that underwent supernumerary larval molts and stayed in the larval stage permanently even after passing the threshold size. We propose that increasing levels of Myo produced by the growing tissues allow larvae to assess their body size and trigger metamorphosis at the threshold size.
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Affiliation(s)
- Lorrie L He
- Department of Biological Sciences, 106 Central St., Wellesley College, Wellesley, MA, 02481, USA
| | - Sara H Shin
- Department of Biological Sciences, 106 Central St., Wellesley College, Wellesley, MA, 02481, USA
| | - Zhou Wang
- Department of Biological Sciences, 106 Central St., Wellesley College, Wellesley, MA, 02481, USA
| | - Isabelle Yuan
- Department of Biological Sciences, 106 Central St., Wellesley College, Wellesley, MA, 02481, USA
| | - Ruthie Weschler
- Department of Biological Sciences, 106 Central St., Wellesley College, Wellesley, MA, 02481, USA
| | - Allison Chiou
- Department of Biological Sciences, 106 Central St., Wellesley College, Wellesley, MA, 02481, USA
| | - Takashi Koyama
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande, 6, 2780-156, Oeiras, Portugal; Department of Biology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark
| | | | - Yuichiro Suzuki
- Department of Biological Sciences, 106 Central St., Wellesley College, Wellesley, MA, 02481, USA.
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Texada MJ, Koyama T, Rewitz K. Regulation of Body Size and Growth Control. Genetics 2020; 216:269-313. [PMID: 33023929 PMCID: PMC7536854 DOI: 10.1534/genetics.120.303095] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 06/29/2020] [Indexed: 12/20/2022] Open
Abstract
The control of body and organ growth is essential for the development of adults with proper size and proportions, which is important for survival and reproduction. In animals, adult body size is determined by the rate and duration of juvenile growth, which are influenced by the environment. In nutrient-scarce environments in which more time is needed for growth, the juvenile growth period can be extended by delaying maturation, whereas juvenile development is rapidly completed in nutrient-rich conditions. This flexibility requires the integration of environmental cues with developmental signals that govern internal checkpoints to ensure that maturation does not begin until sufficient tissue growth has occurred to reach a proper adult size. The Target of Rapamycin (TOR) pathway is the primary cell-autonomous nutrient sensor, while circulating hormones such as steroids and insulin-like growth factors are the main systemic regulators of growth and maturation in animals. We discuss recent findings in Drosophila melanogaster showing that cell-autonomous environment and growth-sensing mechanisms, involving TOR and other growth-regulatory pathways, that converge on insulin and steroid relay centers are responsible for adjusting systemic growth, and development, in response to external and internal conditions. In addition to this, proper organ growth is also monitored and coordinated with whole-body growth and the timing of maturation through modulation of steroid signaling. This coordination involves interorgan communication mediated by Drosophila insulin-like peptide 8 in response to tissue growth status. Together, these multiple nutritional and developmental cues feed into neuroendocrine hubs controlling insulin and steroid signaling, serving as checkpoints at which developmental progression toward maturation can be delayed. This review focuses on these mechanisms by which external and internal conditions can modulate developmental growth and ensure proper adult body size, and highlights the conserved architecture of this system, which has made Drosophila a prime model for understanding the coordination of growth and maturation in animals.
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Affiliation(s)
| | - Takashi Koyama
- Department of Biology, University of Copenhagen, 2100, Denmark
| | - Kim Rewitz
- Department of Biology, University of Copenhagen, 2100, Denmark
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Dong Q, Wang Z, Jiang M, Sun H, Wang X, Li Y, Zhang Y, Cheng H, Chai Y, Shao T, Shi L, Wang Z. Transcriptome analysis of the response provided by Lasiopodomys mandarinus to severe hypoxia includes enhancing DNA repair and damage prevention. Front Zool 2020; 17:9. [PMID: 32256671 PMCID: PMC7106638 DOI: 10.1186/s12983-020-00356-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 03/16/2020] [Indexed: 02/08/2023] Open
Abstract
Background Severe hypoxia induces a series of stress responses in mammals; however, subterranean rodents have evolved several adaptation mechanisms of energy metabolisms and O2 utilization for hypoxia. Mammalian brains show extreme aerobic metabolism. Following hypoxia exposure, mammals usually experience irreversible brain damage and can even develop serious diseases, such as hypoxic ischemic encephalopathy and brain edema. To investigate mechanisms underlying the responses of subterranean rodents to severe hypoxia, we performed a cross-species brain transcriptomic analysis using RNA sequencing and identified differentially expressed genes (DEGs) between the subterranean rodent Lasiopodomys mandarinus and its closely related aboveground species L. brandtii under severe hypoxia (5.0% O2, 6 h) and normoxia (20.9% O2, 6 h). Results We obtained 361 million clean reads, including 69,611 unigenes in L. mandarinus and 69,360 in L. brandtii. We identified 359 and 515 DEGs by comparing the hypoxic and normoxia groups of L. mandarinus and L. brandtii, respectively. Gene Ontology (GO) analysis showed that upregulated DEGs in both species displayed similar terms in response to severe hypoxia; the main difference is that GO terms of L. brandtii were enriched in the immune system. However, in the downregulated DEGs, GO terms of L. mandarinus were enriched in cell proliferation and protein transport and those of L. brandtii were enriched in nuclease and hydrolase activities, particularly in terms of developmental functions. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that upregulated DEGs in L. mandarinus were associated with DNA repair and damage prevention as well as angiogenesis and metastasis inhibition, whereas downregulated DEGs were associated with neuronal synaptic transmission and tumor-associated metabolic pathways. In L. brandtii, upregulated KEGG pathways were enriched in the immune, endocrine, and cardiovascular systems and particularly in cancer-related pathways, whereas downregulated DEGs were associated with environmental information processing and misregulation in cancers. Conclusions L. mandarinus has evolved hypoxia adaptation by enhancing DNA repair, damage prevention, and augmenting sensing, whereas L. brandtii showed a higher risk of tumorigenesis and promoted innate immunity toward severe hypoxia. These results reveal the hypoxic mechanisms of L. mandarinus to severe hypoxia, which may provide research clues for hypoxic diseases.
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Affiliation(s)
- Qianqian Dong
- 1School of Life Sciences, Zhengzhou University, Zhengzhou, 450001 Henan Province China
| | - Zishi Wang
- 1School of Life Sciences, Zhengzhou University, Zhengzhou, 450001 Henan Province China
| | - Mengwan Jiang
- 1School of Life Sciences, Zhengzhou University, Zhengzhou, 450001 Henan Province China
| | - Hong Sun
- 2College of Physical Education (main campus), Zhengzhou University, Zhengzhou, Henan Province China
| | - Xuqin Wang
- 1School of Life Sciences, Zhengzhou University, Zhengzhou, 450001 Henan Province China
| | - Yangwei Li
- 1School of Life Sciences, Zhengzhou University, Zhengzhou, 450001 Henan Province China.,3Central Laboratory, The Affiliated Cancer Hospital of Zhengzhou University, Zhengzhou, 450008 Henan Province China
| | - Yifeng Zhang
- 1School of Life Sciences, Zhengzhou University, Zhengzhou, 450001 Henan Province China
| | - Han Cheng
- 1School of Life Sciences, Zhengzhou University, Zhengzhou, 450001 Henan Province China
| | - Yurong Chai
- 4School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, 450001 Henan Province China
| | - Tian Shao
- 1School of Life Sciences, Zhengzhou University, Zhengzhou, 450001 Henan Province China
| | - Luye Shi
- 1School of Life Sciences, Zhengzhou University, Zhengzhou, 450001 Henan Province China
| | - Zhenlong Wang
- 1School of Life Sciences, Zhengzhou University, Zhengzhou, 450001 Henan Province China
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11
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Frankino WA, Bakota E, Dworkin I, Wilkinson GS, Wolf JB, Shingleton AW. Individual Cryptic Scaling Relationships and the Evolution of Animal Form. Integr Comp Biol 2019; 59:1411-1428. [PMID: 31364716 PMCID: PMC6863759 DOI: 10.1093/icb/icz135] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Artificial selection offers a powerful tool for the exploration of how selection and development shape the evolution of morphological scaling relationships. An emerging approach models the expression and evolution of morphological scaling relationships as a function of variation among individuals in the developmental mechanisms that regulate trait growth. These models posit the existence of genotype-specific morphological scaling relationships that are unseen or "cryptic." Within-population allelic variation at growth-regulating loci determines how these individual cryptic scaling relationships are distributed, and exposure to environmental factors that affect growth determines the size phenotype expressed by each individual on their cryptic, genotype-specific scaling relationship. These models reveal that evolution of the intercept and slope of the population-level static allometry is determined, often in counterintuitive ways, largely by the shape of the distribution of these underlying individual-level scaling relationships. Here we review this modeling framework and present the wing-body size individual cryptic scaling relationships from a population of Drosophila melanogaster. To determine how these models might inform interpretation of published work on scaling relationship evolution, we review studies where artificial selection was applied to alter the parameters of population-level static allometries. Finally, motivated by our review, we outline areas in need of empirical work and describe a research program to address these topics; the approach includes describing the distribution of individual cryptic scaling relationships across populations and environments, empirical testing of the model's predictions, and determining the effects of environmental heterogeneity on realized trait distributions and how this affects allometry evolution.
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Affiliation(s)
- W Anthony Frankino
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204-5001, USA
| | - Eric Bakota
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204-5001, USA
| | - Ian Dworkin
- Department of Biology, McMaster University, Hamilton, Ontario, Canada L9H 6X9
| | - Gerald S Wilkinson
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Jason B Wolf
- Milner Centre for Evolution and Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK
| | - Alexander W Shingleton
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
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12
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A fat-tissue sensor couples growth to oxygen availability by remotely controlling insulin secretion. Nat Commun 2019; 10:1955. [PMID: 31028268 PMCID: PMC6486587 DOI: 10.1038/s41467-019-09943-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 04/10/2019] [Indexed: 12/22/2022] Open
Abstract
Organisms adapt their metabolism and growth to the availability of nutrients and oxygen, which are essential for development, yet the mechanisms by which this adaptation occurs are not fully understood. Here we describe an RNAi-based body-size screen in Drosophila to identify such mechanisms. Among the strongest hits is the fibroblast growth factor receptor homolog breathless necessary for proper development of the tracheal airway system. Breathless deficiency results in tissue hypoxia, sensed primarily in this context by the fat tissue through HIF-1a prolyl hydroxylase (Hph). The fat relays its hypoxic status through release of one or more HIF-1a-dependent humoral factors that inhibit insulin secretion from the brain, thereby restricting systemic growth. Independently of HIF-1a, Hph is also required for nutrient-dependent Target-of-rapamycin (Tor) activation. Our findings show that the fat tissue acts as the primary sensor of nutrient and oxygen levels, directing adaptation of organismal metabolism and growth to environmental conditions. The mechanisms by which organisms adapt their growth according to the availability of oxygen are incompletely understood. Here the authors identify the Drosophila fat body as a tissue regulating growth in response to oxygen sensing via a mechanism involving Hph inhibition, HIF1-a activation and insulin secretion.
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Kouyoumdjian L, Gangloff EJ, Souchet J, Cordero GA, Dupoué A, Aubret F. Transplanting gravid lizards to high elevation alters maternal and embryonic oxygen physiology, but not reproductive success or hatchling phenotype. J Exp Biol 2019; 222:jeb.206839. [DOI: 10.1242/jeb.206839] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 06/19/2019] [Indexed: 12/13/2022]
Abstract
Increased global temperatures have opened previously inhospitable habitats, such as at higher elevations. However, the reduction of oxygen partial pressure with increase in elevation represents an important physiological constraint that may limit colonization of such habitats, even if the thermal niche is appropriate. To test the mechanisms underlying the response to ecologically-relevant levels of hypoxia, we performed a translocation experiment with the common wall lizard (Podarcis muralis), a widespread European lizard amenable to establishing populations outside its natural range. We investigated the impacts of hypoxia on the oxygen physiology and reproductive output of gravid common wall lizards and the subsequent development and morphology of their offspring. Lowland females transplanted to high elevations increased their haematocrit and haemoglobin concentration within days and maintained routine metabolism compared to lizards kept at native elevations. However, transplanted lizards suffered from increased reactive oxygen metabolite production near the oviposition date, suggesting a cost of reproduction at high elevation. Transplanted females and females native to different elevations did not differ in reproductive output (clutch size, egg mass, relative clutch mass, or embryonic stage at oviposition) or in post-oviposition body condition. Developing embryos reduced heart rates and prolonged incubation times at high elevations within the native range and at extreme high elevations beyond the current range, but this reduced oxygen availability did not affect metabolic rate, hatching success, or hatchling size. These results suggest that this opportunistic colonizer is capable of successfully responding to novel environmental constraints in these important life-history stages.
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Affiliation(s)
- Laura Kouyoumdjian
- Station d'Ecologie Théorique et Expérimentale du CNRS – UMR 5321, Moulis, France
| | - Eric J. Gangloff
- Station d'Ecologie Théorique et Expérimentale du CNRS – UMR 5321, Moulis, France
| | - Jérémie Souchet
- Station d'Ecologie Théorique et Expérimentale du CNRS – UMR 5321, Moulis, France
| | - Gerardo A. Cordero
- Fachbereich Geowissenschaften, Eberhard Karls Universität Tübingen, Tübingen, Germany
| | - Andréaz Dupoué
- CNRS UPMC, UMR 7618, iEES Paris, Université Pierre et Marie Curie, Paris, France
| | - Fabien Aubret
- Station d'Ecologie Théorique et Expérimentale du CNRS – UMR 5321, Moulis, France
- School of Molecular and Life Sciences, Curtin University, 6102 WA, Australia
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Römer D, Bollazzi M, Roces F. Carbon dioxide sensing in the social context: Leaf-cutting ants prefer elevated CO 2 levels to tend their brood. JOURNAL OF INSECT PHYSIOLOGY 2018; 108:40-47. [PMID: 29778905 DOI: 10.1016/j.jinsphys.2018.05.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 05/15/2018] [Accepted: 05/17/2018] [Indexed: 06/08/2023]
Abstract
Social insects show temperature and humidity preferences inside their nests to successfully rear brood. In underground nests, ants also encounter rising CO2 concentrations with increasing depth. It is an open question whether they use CO2 as a cue to decide where to place and tend the brood. Leaf-cutting ants do show CO2 preferences for the culturing of their symbiotic fungus. We evaluated their CO2 choices for brood placement in laboratory experiments. Workers of Acromyrmex lundii in the process of relocating brood were offered a binary choice consisting of two interconnected chambers with different CO2 concentrations. Values ranged from atmospheric to high concentrations of 4% CO2. The CO2 preferences shown by workers for themselves and for brood placement were assessed by quantifying the number of workers and relocated brood in each chamber. Ants showed clear CO2 preferences for brood placement. They avoided atmospheric levels, 1% and 4% CO2, and showed a preference for levels of 3%. This is the first report of CO2 preferences for the maintenance of brood in social insects. The observed preferences for brood location were independent of the workers' own CO2 preferences, since they showed no clear-cut pattern. Workers' CO2 preferences for brood maintenance were slightly higher than those reported for fungus culturing, although brood is reared in the same chambers as the fungus in leaf-cutting ant nests. Workers' choices for brood placement in natural nests are likely the result of competing preferences for other environmental factors more crucial for brood survival, aside from those for CO2.
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Affiliation(s)
- Daniela Römer
- Department of Behavioral Physiology and Sociobiology, Biocenter, Am Hubland, University of Würzburg, 97074 Würzburg, Germany; Unidad de Entomología, Departamento de Protección Vegetal, Facultad de Agronomía, Avda. Eugenio Garzon 780, Universidad de la República, 12900 Montevideo, Uruguay.
| | - Martin Bollazzi
- Unidad de Entomología, Departamento de Protección Vegetal, Facultad de Agronomía, Avda. Eugenio Garzon 780, Universidad de la República, 12900 Montevideo, Uruguay.
| | - Flavio Roces
- Department of Behavioral Physiology and Sociobiology, Biocenter, Am Hubland, University of Würzburg, 97074 Würzburg, Germany.
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15
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Wang L, Cui S, Liu Z, Ping Y, Qiu J, Geng X. Inhibition of mitochondrial respiration under hypoxia and increased antioxidant activity after reoxygenation of Tribolium castaneum. PLoS One 2018; 13:e0199056. [PMID: 29902250 PMCID: PMC6002095 DOI: 10.1371/journal.pone.0199056] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 05/30/2018] [Indexed: 12/25/2022] Open
Abstract
Regulating the air in low-oxygen environments protects hermetically stored grains from storage pests damage. However, pests that can tolerate hypoxic stress pose a huge challenge in terms of grain storage. We used various biological approaches to determine the fundamental mechanisms of Tribolium castaneum to cope with hypoxia. Our results indicated that limiting the available oxygen to T. castaneum increased glycolysis and inhibited the Krebs cycle, and that accumulated pyruvic acid was preferentially converted to lactic acid via anaerobic metabolism. Mitochondrial aerobic respiration was markedly suppressed for beetles under hypoxia, which also might have led to mitochondrial autophagy. The enzymatic activity of citrate synthase decreased in insects under hypoxia but recovered within 12 h, which suggested that the beetles recovered from the hypoxia. Moreover, hypoxia-reperfusion resulted in severe oxidative damage to insects, and antioxidant levels increased to defend against the high level of reactive oxygen species. In conclusion, our findings show that mitochondria were the main target in T. castaneum in response to low oxygen. The beetles under hypoxia inhibited mitochondrial respiration and increased antioxidant activity after reoxygenation. Our research advances the field of pest control and makes it possible to develop more efficient strategies for hermetic storage.
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Affiliation(s)
- Lei Wang
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, PR China
| | - Sufen Cui
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, PR China
| | - Zhicheng Liu
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, PR China
| | - Yong Ping
- Bio-X institutes, Shanghai Jiao Tong University, Shanghai, PR China
| | - Jiangping Qiu
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, PR China
| | - Xueqing Geng
- School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, PR China
- * E-mail:
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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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Cordero GA, Andersson BA, Souchet J, Micheli G, Noble DW, Gangloff EJ, Uller T, Aubret F. Physiological plasticity in lizard embryos exposed to high-altitude hypoxia. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2017; 327:423-432. [DOI: 10.1002/jez.2115] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Accepted: 09/19/2017] [Indexed: 12/28/2022]
Affiliation(s)
| | | | - Jeremie Souchet
- Station d'Ecologie Théorique et Expérimentale du CNRS à Moulis; Moulis France
| | - Gaëlle Micheli
- Station d'Ecologie Théorique et Expérimentale du CNRS à Moulis; Moulis France
| | - Daniel W.A. Noble
- Ecology & Evolution Research Centre; School of Biological; Earth and Environmental Sciences; The University of New South Wales; Sydney NSW Australia
| | - Eric J. Gangloff
- Station d'Ecologie Théorique et Expérimentale du CNRS à Moulis; Moulis France
- Department of Ecology; Evolution, and Organismal Biology; Iowa State University; Ames Iowa USA
| | - Tobias Uller
- Department of Biology; Lund University; Lund Sweden
| | - Fabien Aubret
- Station d'Ecologie Théorique et Expérimentale du CNRS à Moulis; Moulis France
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Pan TCF, Hunt von Herbing I. Metabolic plasticity in development: Synergistic responses to high temperature and hypoxia in zebrafish, Danio rerio. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2017; 327:189-199. [PMID: 29356379 DOI: 10.1002/jez.2092] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 07/26/2017] [Accepted: 07/28/2017] [Indexed: 12/14/2022]
Abstract
This study investigated interactions of temperature and hypoxia on metabolic plasticity and regulation in zebrafish, Danio rerio, in the first week of development. Larval morphometry, oxygen consumption, and metabolic responses to acute changes in temperature and oxygen were measured in larvae reared under four conditions, including control (28°C and partial pressures of oxygen [PO2] of 21 kPa), high temperature (31°C), hypoxia (11 kPa), and the two stressors combined. Rearing conditions did not result in consistent morphometric changes; substantial metabolic adjustments, however, were evident. While acute temperature increase resulted in elevated oxygen consumption, with a Q10 of 2.2 ± 0.08, early-staged larvae were able to compensate to chronic temperature rise as routine metabolic rates did not differ between 28°C and 31°C chronic treatments. In contrast, larval responses to chronic and acute hypoxia were similar, with ∼30% decrease in metabolic rates from normoxic values at both temperatures. Further, prior exposure to chronic hypoxia in conjunction with acute high temperature increased Q10 by a factor of 2.5 from 2.2 ± 0.08 to 5.6 ± 0.19. Metabolic suppression by acute hypoxia was independent of any prior exposure conditions. In short, results from this study showed that zebrafish larvae exhibited surprising temperature resilience and metabolic plasticity to a 3°C temperature rise even in their first week of life. Yet exposure to a second stressor (hypoxia) resulted in elevated sensitivity to temperature change that may lead to bioenergetic imbalance due to synergetic effects of temperature and hypoxia on metabolic rates.
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Funch P, Wang T, Pertoldi C, Middelbo AB. Low Oxygen Levels Slow Embryonic Development of Limulus polyphemus. THE BIOLOGICAL BULLETIN 2016; 231:113-119. [PMID: 27820903 DOI: 10.1086/690091] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The American horseshoe crab Limulus polyphemus typically spawns in the upper intertidal zone, where the developing embryos are exposed to large variations in abiotic factors such as temperature, humidity, salinity, and oxygen, which affect the rate of development. It has been shown that embryonic development is slowed at both high and low salinities and temperatures, and that late embryos close to hatching tolerate periodic hypoxia. In this study we investigated the influence of hypoxia on both early and late embryonic development in L. polyphemus under controlled laboratory conditions. Embryos were exposed to four different oxygen levels and their developmental stage was scored every second day. Embryos developed more slowly at both 5% O2 and 10% O2 than at the 21% O2 treatment; late development was arrested when oxygen was reduced to 2%. Our study confims that L. polyphemus not only tolerates pronounced hypoxia in later embryonic developmental stages, but also in earlier, previously unexplored, developmental stages.
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Harrison JF, Manoucheh M, Klok CJ, Campbell JB. Temperature and the Ventilatory Response to Hypoxia in Gromphadorhina portentosa (Blattodea: Blaberidae). ENVIRONMENTAL ENTOMOLOGY 2016; 45:479-483. [PMID: 26721296 DOI: 10.1093/ee/nvv217] [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] [Received: 08/30/2015] [Accepted: 12/03/2015] [Indexed: 06/05/2023]
Abstract
In general, insects respond to hypoxia by increasing ventilation frequency, as seen in most other animals. Higher body temperatures usually also increase ventilation rates, likely due to increases in metabolic rates. In ectothermic air-breathing vertebrates, body temperatures and hypoxia tend to interact significantly, with an increasing responsiveness of ventilation to hypoxia at higher temperatures. Here, we tested whether the same is true in insects, using the Madagascar hissing cockroach, Gromphadorhina portentosa (Schaum) (Blattodea: Blaberidae). We equilibrated individuals to a temperature (beginning at 20 °C), and animals were exposed to step-wise decreases in PO2 (21, 15, 10, and 5 kPa, in that order), and we measured ventilation frequencies from videotapes of abdominal pumping after 15 min of exposure to the test oxygen level. We then raised the temperature by 5 °C, and the protocol was repeated, with tests run at 20, 25, 30, and 35 °C. The 20 °C animals had high initial ventilation rates, possibly due to handling stress, so these animals were excluded from subsequent analyses. Across all temperatures, ventilation increased in hypoxia, but only significantly at 5 kPa PO2 Surprisingly, there was no significant interaction between temperature and oxygen, and no significant effect of temperature on ventilation frequency from 25 to 35 °C. Plausibly, the rise in metabolic rates at higher temperatures in insects is made possible by increasing other aspects of gas exchange, such as decreasing internal PO2, or increases in tidal volume, spiracular opening (duration or amount), or removal of fluid from the tracheoles.
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Affiliation(s)
- Jon F Harrison
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501 (; ; ; ) and
| | - Milad Manoucheh
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501 (; ; ; ) and
| | - C Jaco Klok
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501 (; ; ; ) and
| | - Jacob B Campbell
- School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501 (; ; ; ) and
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21
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Abstract
We previously demonstrated that, while changes in temperature produce dramatic shifts in the time elapsed during
Drosophila melanogaster embryogenesis, the relative timing of events within embryogenesis does not change. However, it was unclear if this uniform scaling is an intrinsic property of developing embryos, or if it is specific to thermal fluctuations. To investigate this, here we characterize the embryonic response to changes in oxygen concentration, which also impact developmental rate, using time-lapse imaging, and find it fundamentally different from the temperature response. Most notably, changes in oxygen levels drive developmental heterochrony, with the timing of several morphological processes showing distinct scaling behaviors. Gut formation is severely slowed by decreases in oxygen, while head involution and syncytial development are less impacted than the rest of development, and the order of several developmental landmarks is inverted at different oxygen levels. These data reveal that the uniform scaling seen with changes in temperature is not a trivial consequence of adjusting developmental rate. The developmental rate changes produced by changing oxygen concentrations dwarf those induced by temperature, and greatly impact survival. While extreme temperatures increase early embryo mortality, mild hypoxia increases arrest and death during mid-embryogenesis and mild hyperoxia increases survival over normoxia.
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Affiliation(s)
- Steven G Kuntz
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA ; Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA, USA
| | - Michael B Eisen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA ; Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA, USA ; Department of Integrative Biology, University of California, Berkeley, CA, USA
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