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Rippamonti J, Dzialowski EM. Thyroid hormone manipulation influences development of endothermy and hatching in white leghorn chickens (Gallus gallus). J Therm Biol 2023; 114:103582. [PMID: 37276745 DOI: 10.1016/j.jtherbio.2023.103582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 04/24/2023] [Accepted: 04/26/2023] [Indexed: 06/07/2023]
Abstract
Chickens experience rapid change in their physiology and metabolism during hatching. We propose that thyroid hormones play a major role in regulating the developmental changes associated with attaining endothermy. To better understand the role thyroid hormones play in hatch timing and development of thermogenic capacity and metabolic rate we manipulated plasma thyroid hormone levels in chicken embryos beginning at 80% development (day 17 of a 21-day incubation) with either a single dose of triiodo-L-thyronine (T3) or the thyroperoxidase inhibitor methimazole (MMI). Manipulation of thyroid hormones altered the timing of hatching, accelerating hatching under hyperthyroid conditions, and prolonging hatching with hypothyroid conditions. Effect sizes comparisons of morphological variables between treatment groups revealed larger heart and body masses in hyperthyroid 1-day post hatch animals. Thyroid hormone manipulation influenced the thermal neutral zone for O2 consumption and body temperature during gradual cooling from 35 to 15 °C of externally pipped embryos and 1-day post hatch chicks. Hyperthyroid EP animals had a wider thermal neutral zone during cooling when compared to control animals. At the temperatures tested, the hypothyroid animals did not exhibit a thermal neutral zone. Similar differences between treatments in the breadth of the thermal neutral zone carried through to 1-day post hatch chickens. These findings suggest that thyroid manipulations influence the timing and development of the animal's thermogenic response to cooling.
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Affiliation(s)
- Jessica Rippamonti
- Department of Biological Sciences, University of North Texas, Denton, TX, 76201, USA.
| | - Edward M Dzialowski
- Department of Biological Sciences, University of North Texas, Denton, TX, 76201, USA
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2
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Thyroid and Corticosteroid Signaling in Amphibian Metamorphosis. Cells 2022; 11:cells11101595. [PMID: 35626631 PMCID: PMC9139329 DOI: 10.3390/cells11101595] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 04/28/2022] [Accepted: 05/05/2022] [Indexed: 01/25/2023] Open
Abstract
In multicellular organisms, development is based in part on the integration of communication systems. Two neuroendocrine axes, the hypothalamic–pituitary–thyroid and the hypothalamic–pituitary–adrenal/interrenal axes, are central players in orchestrating body morphogenesis. In all vertebrates, the hypothalamic–pituitary–thyroid axis controls thyroid hormone production and release, whereas the hypothalamic–pituitary–adrenal/interrenal axis regulates the production and release of corticosteroids. One of the most salient effects of thyroid hormones and corticosteroids in post-embryonic developmental processes is their critical role in metamorphosis in anuran amphibians. Metamorphosis involves modifications to the morphological and biochemical characteristics of all larval tissues to enable the transition from one life stage to the next life stage that coincides with an ecological niche switch. This transition in amphibians is an example of a widespread phenomenon among vertebrates, where thyroid hormones and corticosteroids coordinate a post-embryonic developmental transition. The review addresses the functions and interactions of thyroid hormone and corticosteroid signaling in amphibian development (metamorphosis) as well as the developmental roles of these two pathways in vertebrate evolution.
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3
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Hsu BY, Pakanen VM, Boner W, Doligez B, Eeva T, Groothuis TGG, Korpimäki E, Laaksonen T, Lelono A, Monaghan P, Sarraude T, Thomson RL, Tolvanen J, Tschirren B, Vásquez RA, Ruuskanen S. Maternally-transferred thyroid hormones and life-history variation in birds. J Anim Ecol 2022; 91:1489-1506. [PMID: 35470435 PMCID: PMC9546341 DOI: 10.1111/1365-2656.13708] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 03/21/2022] [Indexed: 12/04/2022]
Abstract
In vertebrates, thyroid hormones (THs) play an important role in the regulation of growth, development, metabolism, photoperiodic responses and migration. Maternally transferred THs are important for normal early phase embryonic development when embryos are not able to produce endogenous THs. Previous studies have shown that variation in maternal THs within the physiological range can influence offspring phenotype. Given the essential functions of maternal THs in development and metabolism, THs may be a mediator of life‐history variation across species. We tested the hypothesis that differences in life histories are associated with differences in maternal TH transfer across species. Using birds as a model, we specifically tested whether maternally transferred yolk THs covary with migratory status, developmental mode and traits related to pace‐of‐life (e.g. basal metabolic rate, maximum life span). We collected un‐incubated eggs (n = 1–21 eggs per species, median = 7) from 34 wild and captive bird species across 17 families and six orders to measure yolk THs [both triiodothyronine (T3) and thyroxine (T4)], compiled life‐history trait data from the literature and used Bayesian phylogenetic mixed models to test our hypotheses. Our models indicated that both concentrations and total amounts of the two main forms of THs (T3 and T4) were higher in the eggs of migratory species compared to resident species, and total amounts were higher in the eggs of precocial species, which have longer prenatal developmental periods, than in those of altricial species. However, maternal yolk THs did not show clear associations with pace‐of‐life‐related traits, such as fecundity, basal metabolic rate or maximum life span. We quantified interspecific variation in maternal yolk THs in birds, and our findings suggest higher maternal TH transfer is associated with the precocial mode of development and migratory status. Whether maternal THs represent a part of the mechanism underlying the evolution of precocial development and migration or a consequence of such life histories is currently unclear. We therefore encourage further studies to explore the physiological mechanisms and evolutionary processes underlying these patterns.
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Affiliation(s)
- Bin-Yan Hsu
- Department of Biology, University of Turku, Finland
| | - Veli-Matti Pakanen
- Ecology and Genetics Research Unit, University of Oulu, Finland.,Department of Biological and Environmental Sciences, University of Gothenburg, Sweden
| | - Winnie Boner
- Institute of Biodiversity, Animal Healthy and Comparative Medicine, University of Glasgow, Scotland, United Kingdom
| | - Blandine Doligez
- Department of Biometry and Evolutionary Biology, CNRS UMR 5558, Université de Lyon 1, France
| | - Tapio Eeva
- Department of Biology, University of Turku, Finland
| | - Ton G G Groothuis
- Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, the Netherlands
| | | | | | - Asmoro Lelono
- Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, the Netherlands.,Biology Department, Natural Sciences and Mathematics Faculty, Jember University of Indonesia, Indonesia
| | - Pat Monaghan
- Institute of Biodiversity, Animal Healthy and Comparative Medicine, University of Glasgow, Scotland, United Kingdom
| | - Tom Sarraude
- Department of Biology, University of Turku, Finland.,Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, the Netherlands
| | - Robert L Thomson
- Fitzpatrick Institute of African Ornithology, DST-NRF Centre of Excellence, University of Cape Town, South Africa
| | - Jere Tolvanen
- Ecology and Genetics Research Unit, University of Oulu, Finland
| | - Barbara Tschirren
- Centre for Ecology and Conservation, University of Exeter, United Kingdom
| | - Rodrigo A Vásquez
- Instituto de Ecología y Biodiversidad, Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Suvi Ruuskanen
- Department of Biology, University of Turku, Finland.,Department of Biological and Environmental Sciences, University of Jyväskylä, Finland
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Population genetic differentiation and genomic signatures of adaptation to climate in an abundant lizard. Heredity (Edinb) 2022; 128:271-278. [PMID: 35277668 PMCID: PMC8987050 DOI: 10.1038/s41437-022-00518-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 02/15/2022] [Accepted: 02/16/2022] [Indexed: 12/18/2022] Open
Abstract
Species distributed across climatic gradients will typically experience spatial variation in selection, but gene flow can prevent such selection from causing population genetic differentiation and local adaptation. Here, we studied genomic variation of 415 individuals across 34 populations of the common wall lizard (Podarcis muralis) in central Italy. This species is highly abundant throughout this region and populations belong to a single genetic lineage, yet there is extensive phenotypic variation across climatic regimes. We used redundancy analysis to, first, quantify the effect of climate and geography on population genomic variation in this region and, second, to test if climate consistently sorts specific alleles across the landscape. Climate explained 5% of the population genomic variation across the landscape, about half of which was collinear with geography. Linear models and redundancy analyses identified loci that were significantly differentiated across climatic regimes. These loci were distributed across the genome and physically associated with genes putatively involved in thermal tolerance, regulation of temperature-dependent metabolism and reproductive activity, and body colouration. Together, these findings suggest that climate can exercise sufficient selection in lizards to promote genetic differentiation across the landscape in spite of high gene flow.
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Field A, McGlashan JK, Salmon M. Evidence for Synchronous Hatching in Marine Turtle (Caretta caretta) Embryos and Its Influence on the Timing of Nest Emergence. CHELONIAN CONSERVATION AND BIOLOGY 2021. [DOI: 10.2744/ccb-1489.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Angela Field
- Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida 33431 USA [; ]
| | - Jessica K. McGlashan
- School of Science and Health, University of Western Sydney, Locked Bag 1797, Penrith South DC, NSW 2751 Australia []
| | - Michael Salmon
- Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida 33431 USA [; ]
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6
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Rousseau K, Dufour S, Sachs LM. Interdependence of Thyroid and Corticosteroid Signaling in Vertebrate Developmental Transitions. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.735487] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Post-embryonic acute developmental processes mainly allow the transition from one life stage in a specific ecological niche to the next life stage in a different ecological niche. Metamorphosis, an emblematic type of these post-embryonic developmental processes, has occurred repeatedly and independently in various phylogenetic groups throughout metazoan evolution, such as in cnidarian, insects, molluscs, tunicates, or vertebrates. This review will focus on metamorphoses and developmental transitions in vertebrates, including typical larval metamorphosis in anuran amphibians, larval and secondary metamorphoses in teleost fishes, egg hatching in sauropsids and birth in mammals. Two neuroendocrine axes, the hypothalamic-pituitary-thyroid and the hypothalamic-pituitary-adrenal/interrenal axes, are central players in the regulation of these life transitions. The review will address the molecular and functional evolution of these axes and their interactions. Mechanisms of integration of internal and environmental cues, and activation of these neuroendocrine axes represent key questions in an “eco-evo-devo” perspective of metamorphosis. The roles played by developmental transitions in the innovation, adaptation, and plasticity of life cycles throughout vertebrates will be discussed. In the current context of global climate change and habitat destruction, the review will also address the impact of environmental factors, such as global warming and endocrine disruptors on hypothalamic-pituitary-thyroid and hypothalamic-pituitary-adrenal/interrenal axes, and regulation of developmental transitions.
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7
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Mariette MM, Clayton DF, Buchanan KL. Acoustic developmental programming: a mechanistic and evolutionary framework. Trends Ecol Evol 2021; 36:722-736. [PMID: 34052045 DOI: 10.1016/j.tree.2021.04.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Revised: 04/13/2021] [Accepted: 04/14/2021] [Indexed: 11/16/2022]
Abstract
Conditions experienced prenatally, by modulating developmental processes, have lifelong effects on individual phenotypes and fitness, ultimately influencing population dynamics. In addition to maternal biochemical cues, prenatal sound is emerging as a potent alternative source of information to direct embryonic development. Recent evidence suggests that prenatal acoustic signals can program individual phenotypes for predicted postnatal environmental conditions, which improves fitness. Across taxonomic groups, embryos have now been shown to have immediate adaptive responses to external sounds and vibrations, and direct developmental effects of sound and noise are increasingly found. Establishing the full developmental, ecological, and evolutionary impact of early soundscapes will reveal how embryos interact with the external world, and potentially transform our understanding of developmental plasticity and adaptation to changing environments.
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Affiliation(s)
- Mylene M Mariette
- Centre for Integrative Ecology, Deakin University, Geelong, VIC 3216, Australia.
| | - David F Clayton
- Department of Biological and Experimental Psychology, Queen Mary University of London, London E1 4NS, UK
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Sirsat TS, Dzialowski EM. Manipulating plasma thyroid hormone levels at hatching alters development of endothermy and ventilation in Pekin duck ( Anas platyrhynchos domestica). J Exp Biol 2020; 223:jeb237701. [PMID: 33046566 DOI: 10.1242/jeb.237701] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 10/05/2020] [Indexed: 08/25/2023]
Abstract
At hatching in precocial birds, there are rapid physiological and metabolic phenotypic changes associated with attaining endothermy. During the transition to ex ovo life, thyroid hormone levels naturally increase, peaking at hatching, and then decline. To better understand the role of the natural increase in thyroid hormone at hatching in regulating the developmental trajectory of the Pekin duck's endothermic phenotype, we examined development of O2 consumption (V̇O2 ) and ventilation (frequency, tidal volume and minute ventilation) while inhibiting the developmental increase in thyroid hormones that occurs at hatching via administration of the thyroid-peroxidase inhibitor methimazole (MMI) or accelerating the developmental increase via triiodothyronine (T3) supplementation. Animals were dosed only on day 24 of a 28-day incubation period and studied on incubation day 25, during external pipping (EP) and 1 day post-hatching (dph). On day 25, there was an increase in V̇O2 in the hyperthyroid treatment compared with the other two treatments. During the EP stage, there was a significant effect of thyroid status on V̇O2 , with hyperthyroid V̇O2 being highest and hypothyroid V̇O2 the lowest. By 1 dph, the supplemented T3 and control animals had similar V̇O2 responses to cooling with comparable thermal neutral zones followed by increased V̇O2 Hypothyroid 1 dph hatchlings had a lower resting V̇O2 that did not increase to the same extent as the supplemented T3 and control animals during cooling. During EP, inhibiting the rise in T3 resulted in embryos with lower ventilation frequency and tidal volume than control and supplemented T3 embryos. At 1 dph, ventilation frequency of all animals increased during cooling, but tidal volume only increased in supplemented T3 and control hatchlings. Our data support the role of the late incubation increase in T3 in regulating the systemic development of endothermic metabolic capacity and associated control of ventilation occurring at hatching of the Pekin duck.
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Affiliation(s)
- Tushar S Sirsat
- Developmental Integrative Biology Research Group, Department of Biological Sciences, 1155 Union Circle #305220, University of North Texas, Denton, TX 76203, USA
| | - Edward M Dzialowski
- Developmental Integrative Biology Research Group, Department of Biological Sciences, 1155 Union Circle #305220, University of North Texas, Denton, TX 76203, USA
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9
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Warner DA, Mitchell TS, Bodensteiner BL, Janzen FJ. Sex and Incubation Temperature Independently Affect Embryonic Development and Offspring Size in a Turtle with Temperature-Dependent Sex Determination. Physiol Biochem Zool 2020; 93:62-74. [DOI: 10.1086/706786] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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10
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Du WG, Shine R, Ma L, Sun BJ. Adaptive responses of the embryos of birds and reptiles to spatial and temporal variations in nest temperatures. Proc Biol Sci 2019; 286:20192078. [PMID: 31744441 DOI: 10.1098/rspb.2019.2078] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Natural nests of egg-laying birds and reptiles exhibit substantial thermal variation, at a range of spatial and temporal scales. Rates and trajectories of embryonic development are highly sensitive to temperature, favouring an ability of embryos to respond adaptively (i.e. match their developmental biology to local thermal regimes). Spatially, thermal variation can be significant within a single nest (top to bottom), among adjacent nests (as a function of shading, nest depth etc.), across populations that inhabit areas with different weather conditions, and across species that differ in climates occupied and/or nest characteristics. Thermal regimes also vary temporally, in ways that generate differences among nests within a single population (e.g. due to seasonal timing of laying), among populations and across species. Anthropogenic activities (e.g. habitat clearing, climate change) add to this spatial and temporal diversity in thermal regimes. We review published literature on embryonic adaptations to spatio-temporal heterogeneity in nest temperatures. Although relatively few taxa have been studied in detail, and proximate mechanisms remain unclear, our review identifies many cases in which natural selection appears to have fine-tuned embryogenesis to match local thermal regimes. Developmental rates have been reported to differ between uppermost versus lower eggs within a single nest, between eggs laid early versus late in the season, and between populations from cooler versus warmer climates. We identify gaps in our understanding of thermal adaptations of early (embryonic) phases of the life history, and suggest fruitful opportunities for future research.
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Affiliation(s)
- Wei-Guo Du
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China.,Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming 650223, People's Republic of China
| | - Richard Shine
- Department of Biological Sciences, Macquarie University, North Ryde, New South Wales 2109, Australia
| | - Liang Ma
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China
| | - Bao-Jun Sun
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China
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11
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McGlashan JK, Thompson MB, Janzen FJ, Spencer R. Environmentally induced phenotypic plasticity explains hatching synchrony in the freshwater turtle
Chrysemys picta. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2018; 329:362-372. [DOI: 10.1002/jez.2217] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 07/03/2018] [Accepted: 07/05/2018] [Indexed: 11/07/2022]
Affiliation(s)
- Jessica K. McGlashan
- School of Science and Health, University of Western Sydney Penrith South DC NSW Australia
| | - Michael B. Thompson
- School of Biological Sciences, Heydon‐Laurence Building (A08), The University of Sydney Sydney NSW Australia
| | - Fredric J. Janzen
- Department of Ecology Evolution and Organismal Biology, Iowa State University Ames Iowa
| | - Ricky‐John Spencer
- School of Science and Health, University of Western Sydney Penrith South DC NSW Australia
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12
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Thompson M, Coe BH, Andrews RM, Cristol DA, Crossley DA, Hopkins WA. Agricultural land use creates evolutionary traps for nesting turtles and is exacerbated by mercury pollution. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2018; 329:230-243. [DOI: 10.1002/jez.2198] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Revised: 05/01/2018] [Accepted: 05/07/2018] [Indexed: 11/06/2022]
Affiliation(s)
- Molly Thompson
- Department of Fish and Wildlife Conservation; Virginia Tech; Blacksburg Virginia
| | - Brittney H. Coe
- Department of Fish and Wildlife Conservation; Virginia Tech; Blacksburg Virginia
| | - Robin M. Andrews
- Department of Biological Sciences; Virginia Tech; Blacksburg Virginia
| | - Daniel A. Cristol
- Department of Biology; College of William & Mary; Williamsburg Virginia
| | - Dane A. Crossley
- Department of Biological Sciences; University of North Texas; Denton Texas
| | - William A. Hopkins
- Department of Fish and Wildlife Conservation; Virginia Tech; Blacksburg Virginia
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13
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Thyroid hormone manipulation influences development of cardiovascular regulation in embryonic Pekin duck, Anas platyrhynchos domestica. J Comp Physiol B 2018; 188:843-853. [PMID: 29948159 DOI: 10.1007/s00360-018-1166-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 05/08/2018] [Accepted: 05/22/2018] [Indexed: 12/15/2022]
Abstract
Thyroid hormones are key regulators of avian metabolism and may play a significant role in development at hatching. To better understand the role of thyroid hormones in avian development, we examined autonomic control of heart rate and blood pressure while manipulating thyroid hormone levels in the late stage embryonic Pekin duck (Anas platyrhynchos domestica). Thyroid hormone levels were manipulated on day 24 of a 28-day incubation period with the thyroperoxidase inhibitor methimazole (MMI), triiodothyronine (T3), or saline. On day 25 of incubation, autonomic tone on cardiovascular function was studied by injections of cholinergic and adrenergic receptor antagonists. Embryos from all treatment groups expressed a cholinergic and β-adrenergic tone on heart rate at this age. Cholinergic blockade with atropine produced a larger change in heart rate in the hyperthyroid animals compared with euthyroid animals. In response to β-adrenergic blockade, hyperthyroid conditions produced a larger decrease in heart rate compared with euthyroid animals, with no change in mean arterial blood pressure. In response to α-adrenergic blockade, mean arterial blood pressure decreased in the euthyroid animals and more developed hyperthyroid animals. Collectively, the data indicate that elevated levels of T3 can influence maturation of cholinergic and adrenergic receptor-mediated cardiovascular regulation in developing Pekin ducks near the end of incubation.
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14
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Ruuskanen S, Hsu BY. Maternal Thyroid Hormones: An Unexplored Mechanism Underlying Maternal Effects in an Ecological Framework. Physiol Biochem Zool 2018; 91:904-916. [DOI: 10.1086/697380] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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15
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Sun BJ, Li T, Mu Y, McGlashan JK, Georges A, Shine R, Du WG. Thyroid hormone modulates offspring sex ratio in a turtle with temperature-dependent sex determination. Proc Biol Sci 2017; 283:rspb.2016.1206. [PMID: 27798296 DOI: 10.1098/rspb.2016.1206] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 09/29/2016] [Indexed: 11/12/2022] Open
Abstract
The adaptive significance of temperature-dependent sex determination (TSD) has attracted a great deal of research, but the underlying mechanisms by which temperature determines the sex of a developing embryo remain poorly understood. Here, we manipulated the level of a thyroid hormone (TH), triiodothyronine (T3), during embryonic development (by adding excess T3 to the eggs of the red-eared slider turtle Trachemys scripta, a reptile with TSD), to test two competing hypotheses on the proximate basis for TSD: the developmental rate hypothesis versus the hormone hypothesis Exogenous TH accelerated embryonic heart rate (and hence metabolic rate), developmental rate, and rates of early post-hatching growth. More importantly, hyperthyroid conditions depressed expression of Cyp19a1 (the gene encoding for aromatase) and levels of oestradiol, and induced more male offspring. This result is contrary to the direction of sex-ratio shift predicted by the developmental rate hypothesis, but consistent with that predicted by the hormone hypothesis Our results suggest an important role for THs in regulating sex steroid hormones, and therefore, in affecting gonadal sex differentiation in TSD reptiles. Our study has implications for the conservation of TSD reptiles in the context of global change because environmental contaminants may disrupt the activity of THs, and thereby affect offspring sex in TSD reptiles.
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Affiliation(s)
- Bao-Jun Sun
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China
| | - Teng Li
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China
| | - Yi Mu
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China
| | - Jessica K McGlashan
- Science and Health Hawkesbury Institute, University of Western Sydney, New South Wales 2751, Australia
| | - Arthur Georges
- Institute for Applied Ecology, University of Canberra, Australian Capital Territory 2601, Australia
| | - Richard Shine
- School of Life and Environmental Sciences A08, University of Sydney, New South Wales 2006, Australia
| | - Wei-Guo Du
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China
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16
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Shine R, Wapstra E, Olsson M. Seasonal shifts along the oviparity–viviparity continuum in a cold‐climate lizard population. J Evol Biol 2017; 31:4-13. [DOI: 10.1111/jeb.13202] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 10/22/2017] [Indexed: 11/29/2022]
Affiliation(s)
- R. Shine
- School of Life and Environmental Sciences University of Sydney Sydney NSW Australia
| | - E. Wapstra
- School of Biological Sciences University of Tasmania Hobart Tasmania Australia
| | - M. Olsson
- Department of Biological and Environmental Sciences University of Gothenburg Gothenburg Sweden
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