1
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Marroquín-Flores RA, Paitz RT, Bowden RM. Temperature fluctuations and estrone sulfate affect gene expression via different mechanisms to promote female development in a species with temperature-dependent sex determination. J Exp Biol 2022; 225:276050. [PMID: 35860927 DOI: 10.1242/jeb.244211] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 07/18/2022] [Indexed: 11/20/2022]
Abstract
Variation in developmental conditions can affect a variety of embryonic processes and shape a number of phenotypic characteristics that can affect offspring throughout their lives. This is particularly true of oviparous species where development typically occurs outside of the female, and studies have shown that traits such as survival and behavior can be altered by both temperature and exposure to steroid hormones during development. In species with temperature-dependent sex determination (TSD), the fate of gonadal development can be affected by temperature and by maternal estrogens present in the egg at oviposition and there is evidence that these factors can affect gene expression patterns. Here, we explore how thermal fluctuations and exposure to an estrogen metabolite, estrone sulfate, affect the expression of several genes known to be involved in sexual differentiation; Kdm6b, Dmrt1, Sox9, FoxL2, and Cyp19A1. We found that most of the genes responded to both temperature and estrone sulfate exposure, but that the responses to these factors was not identical in that estrone sulfate effects occur downstream of temperature effects. Our findings demonstrate that conjugated hormones such as estrone sulfate are capable of influencing temperature dependent pathways to potentially alter how embryos respond to temperature and highlight the importance of studying the interaction of maternal hormone and temperature effects.
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Affiliation(s)
| | - Ryan T Paitz
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Rachel M Bowden
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
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2
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Paitz RT, Dugas MB. Steroid levels in frog eggs: Manipulations, developmental changes, and implications for maternal steroid effects. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2022; 337:293-302. [PMID: 34905660 DOI: 10.1002/jez.2566] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 11/21/2021] [Accepted: 11/23/2021] [Indexed: 06/14/2023]
Abstract
Exposure to maternally derived steroids during embryonic development can elicit phenotypic effects in the resulting offspring. Studies of maternal steroid effects, especially rich in mammals and birds, have offered exciting insights into the evolution of maternal effects in vertebrates. To extend this literature, we quantified levels of steroids in the eggs of four neotropical dendrobatid frogs that lay terrestrial clutches, a reproductive strategy that has evolved multiple times in amphibians. Building on our observational results, we then manipulated levels of pregnenolone and progesterone in eggs of one species and examined how this affected steroid levels during development. Eggs of all four species had detectable steroids levels, with progestogens being more abundant than androgens and glucocorticoids. Estrogens could not be detected. Immersion of frog eggs in a solution containing pregnenolone and progesterone resulted in elevated levels of both steroids early in development, but levels declined and were similar to those in unmanipulated eggs by the end of development. Treated eggs also exhibited a transient increase in levels of steroids that can be produced from pregnenolone and progesterone. Overall, our findings demonstrate that frog eggs contain steroids similar to what has been observed in other egg-laying vertebrates. During development, steroid levels are dynamic, further suggesting developing embryos regulate exposure to maternal steroids. These results set the stage for investigating the causes and consequences of maternal steroid effects in frogs.
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Affiliation(s)
- Ryan T Paitz
- School of Biological Sciences, Illinois State University, Normal, Illinois, USA
| | - Matthew B Dugas
- School of Biological Sciences, Illinois State University, Normal, Illinois, USA
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3
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Kottmann JS, Tveiten H, Miest JJ, Tomkiewicz J. Sex steroid dynamics and mRNA transcript profiles of growth- and development-related genes during embryogenesis following induced follicular maturation in European eel. Gen Comp Endocrinol 2021; 311:113854. [PMID: 34265345 DOI: 10.1016/j.ygcen.2021.113854] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 07/07/2021] [Accepted: 07/09/2021] [Indexed: 12/24/2022]
Abstract
Hormones and mRNA transcripts of maternal origin deposited in the egg may affect early embryonic development in oviparous species. These hormones include steroids, such as estradiol-17β (E2), testosterone (T), 11-ketotestosterone (11-kt), 17α,20ß-dihydroxy-4-pregnen-3-one (DHP), and cortisol, which also play an important role in fish reproduction. In European eel, Anguilla anguilla, which does not reproduce naturally in captivity, vitellogenesis in female broodstock is commonly induced by administration of salmon or carp pituitary extract (PE) as an exogenous source of gonadotropins, while follicular maturation is stimulated by a priming dose of PE followed by provision of DHP as a maturation inducing hormone. In this regard, the main purpose of the present study was to evaluate effects of induced follicular maturation on reproductive success in European eel, focusing on maternal transfer and dynamics of steroids and mRNA transcripts of growth- and development-related genes throughout embryogenesis. The results showed that maternal blood plasma concentrations of E2, T and DHP were reflected in the unfertilized eggs. Moreover, a negative relationship between concentrations of E2 and DHP in eggs and embryos and quality parameters measured as fertilization success, cleavage abnormalities, embryonic survival, and hatch success was found. Concomitant mRNA transcript abundance analysis including genes involved in stress response (hsp70, hsp90), somatotropic axis (gh, igf1, igf2a, igf2b), lipid (cpt1a, cpt1b, pigf5) and thyroid metabolism (dio1, dio2, dio3, thrαb, thrβa, thrβb) varied among unfertilized egg batches. For the majority of genes, mRNA abundance increased during the maternal-to-zygotic transition in connection to activation of the transcription of the embryos own genome. mRNA abundance of dio1, cpt1a and cpt1b throughout embryogenesis was related to embryonic developmental competence. Notably, mRNA abundance of dio3 was positively associated with E2 concentrations, while the mRNA abundance of thrαb was negatively related to T concentrations in the unfertilized eggs, which may suggest an interaction between the thyroid and steroid hormone systems. Altogether, maternal plasma concentrations of E2 and DHP were reflected in the eggs, with high concentrations of these steroids in the eggs being negatively associated with embryonic developmental competence. Additionally, high transcript levels of two of the investigated genes (dio1, cpt1b) were positively associated with embryonic developmental competence. This study reveals maternal transfer of steroids and mRNA transcripts to the eggs, which may be significant contributors to the variability in embryonic survival observed in European eel captive reproduction.
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Affiliation(s)
- Johanna S Kottmann
- National Institute of Aquatic Resources, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
| | - Helge Tveiten
- UiT Arctic University of Norway, 9019 Tromsø, Norway
| | - Joanna J Miest
- School of Science, University of Greenwich, Chatham Maritime, Kent ME4 4TB, United Kingdom
| | - Jonna Tomkiewicz
- National Institute of Aquatic Resources, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
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4
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Paitz RT, Cagney E. In ovo metabolism of progesterone to 5β-pregnanedione in chicken eggs: Implications for how yolk progesterone influences embryonic development. Gen Comp Endocrinol 2019; 282:113221. [PMID: 31301283 DOI: 10.1016/j.ygcen.2019.113221] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 07/09/2019] [Accepted: 07/09/2019] [Indexed: 01/30/2023]
Abstract
Progesterone has received substantial attention for the essential role it plays in establishing and maintaining pregnancy in placental vertebrates. Despite the prevalence of progesterone during development, relatively little is known about how embryos respond to progesterone. This is true of placental vertebrates as well as egg-laying vertebrates where levels of progesterone in the yolk tend to be higher than most other steroids in the yolk. Bird eggs provide an opportunity to investigate the effects of progesterone on embryonic development because progesterone can be easily manipulated without any confounding effects on maternal physiology. To understand how progesterone might influence embryonic development, it is important to characterize the metabolic fate of progesterone given its potential to be converted to a wide range of steroids. We investigated the metabolic fate of tritiated progesterone over the first four days of development using chicken eggs (Gallus gallus) and identified 5β-pregnanedione as the primary metabolite during this period. After only one day of development, 5β-pregnanedione could be detected within the yolk. Levels of 5β-pregnanedione in both the yolk and albumen tended to rise early in development but conjugated metabolites began to accumulate towards the end of our sampling period. Additionally, in vitro assays using embryo homogenates collected after 72 h of development demonstrated that embryos were capable of carrying out the conversion of progesterone to 5β-pregnanedione. Overall these results have important implications for deciphering the mechanisms through which yolk progesterone might influence embryonic development. Effects could arise via progesterone receptors or receptors capable of binding 5β-pregnanedione but we found no evidence that progesterone is serving as a precursor for androgen or estrogen production.
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Affiliation(s)
- Ryan T Paitz
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA.
| | - Erin Cagney
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
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5
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Steroid receptors and their regulation in avian extraembryonic membranes provide a novel substrate for hormone mediated maternal effects. Sci Rep 2019; 9:11501. [PMID: 31395925 PMCID: PMC6687743 DOI: 10.1038/s41598-019-48001-x] [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] [Received: 09/19/2018] [Accepted: 07/03/2019] [Indexed: 01/12/2023] Open
Abstract
Exposure of the vertebrate embryo to maternal hormones can have long-lasting effects on its phenotype, which has been studied extensively by experimentally manipulating maternal steroids, mostly androgens, in bird eggs. Yet, there is a severe lack of understanding of how and when these effects are actually mediated, hampering both underlying proximate and ultimate explanations. Here we report a novel finding that the embryo expresses androgen receptor (AR) and estrogen receptor (ERα) mRNA in its extraembryonic membranes (EMs) as early as before its own hormone production starts, suggesting a novel substrate for action of maternal hormones on the offspring. We also report the first experimental evidence for steroid receptor regulation in the avian embryo in response to yolk steroid levels: the level of AR is dependent on yolk androgen levels only in the EMs but not in body tissues, suggesting embryonic adaptation to maternal hormones. The results also solve the problem of uptake of lipophilic steroids from the yolk, why they affect multiple traits, and how they could mediate maternal effects without affecting embryonic sexual differentiation.
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6
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Kumar N, van Faassen M, Kema I, Gahr M, Groothuis TGG. Early embryonic modification of maternal hormones differs systematically among embryos of different laying order: A study in birds. Gen Comp Endocrinol 2018; 269:53-59. [PMID: 30110617 DOI: 10.1016/j.ygcen.2018.08.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 08/07/2018] [Accepted: 08/07/2018] [Indexed: 12/17/2022]
Abstract
Vertebrate embryos are exposed to maternal hormones that can profoundly affect their later phenotype. Although it is known that the embryo can metabolize these maternal hormones, the metabolic outcomes, their quantitative dynamics and timing are poorly understood. Moreover, it is unknown whether embryos can adjust their metabolic activity to, for example, hormones or other maternal signals. We studied the dynamics of maternal steroids in fertilized and unfertilized rock pigeon eggs during early incubation. Embryos of this species are naturally exposed to different amounts of maternal steroids in the egg according to their laying position, which provides a natural context to study differential embryonic regulation of the maternal signals. We used mass spectrometric analyses to map changes in the androgen and estrogen pathways of conversion. We show that the active hormones are heavily metabolized only in fertilized eggs, with a corresponding increase in supposedly less potent metabolites already within one-fourth of total incubation period. Interestingly, the rate of androgen metabolism was different between embryos in different laying positions. The results also warrant a re-interpretation of the timing of hormone mediated maternal effects and the role of the supposedly biologically inactive metabolites. Furthermore, the results also provide a potential solution as to how the embryo can prevent maternal steroids in the egg from interfering with its sexual differentiation processes as we show that the embryo can metabolize most of the maternal steroids before sexual differentiation starts.
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Affiliation(s)
- Neeraj Kumar
- Behavioural Biology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, the Netherlands; Behavioural Neurobiology, Max Planck Institute for Ornithology, Seewiesen, Germany.
| | - Martijn van Faassen
- Laboratory Medicine, University Medical Center Groningen, University of Groningen, the Netherlands
| | - Ido Kema
- Laboratory Medicine, University Medical Center Groningen, University of Groningen, the Netherlands
| | - Manfred Gahr
- Behavioural Neurobiology, Max Planck Institute for Ornithology, Seewiesen, Germany
| | - Ton G G Groothuis
- Behavioural Biology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, the Netherlands
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7
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Bowden RM, Paitz RT. Temperature fluctuations and maternal estrogens as critical factors for understanding temperature-dependent sex determination in nature. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2018; 329:177-184. [PMID: 29806743 PMCID: PMC6141314 DOI: 10.1002/jez.2183] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 04/29/2018] [Accepted: 05/02/2018] [Indexed: 12/25/2022]
Abstract
Vertebrates with temperature-dependent sex determination (TSD) have justifiably received a lot of attention when it comes to the potential effects of climate change. Freshwater turtles have long been used to characterize the physiological and genetic mechanisms underlying TSD and provide a great system to investigate how changing climatic conditions will affect vertebrates with TSD. Unfortunately, most of what we know about the mechanisms underlying TSD comes from laboratory conditions that do not accurately mimic natural conditions (i.e., constant incubation temperatures and supraphysiological steroid manipulations). In this paper, we review recent advances in our understanding of how TSD operates in nature that arose from studies using more natural fluctuating incubation temperatures and natural variation in maternal estrogens within the yolk. By incorporating more natural conditions into laboratory studies, we are better able to use these studies to predict how changing climatic conditions will affect species with TSD.
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Affiliation(s)
- Rachel M. Bowden
- School of Biological Sciences, Illinois State University, Normal, IL 61790-4120
| | - Ryan T. Paitz
- School of Biological Sciences, Illinois State University, Normal, IL 61790-4120
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8
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Della Costa NS, Navarro JL, Busso JM, Marin RH, Martella MB. Distribution and concentration of maternal progesterone in the yolk of Greater Rhea eggs (Rhea americana). JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2018; 327:143-148. [PMID: 29356448 DOI: 10.1002/jez.2073] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 04/04/2017] [Accepted: 04/05/2017] [Indexed: 01/28/2023]
Abstract
Progesterone is the most concentrated maternal yolk steroid characterized to date in birds; however, no information about it is available in ratite eggs. We collected freshly laid eggs from zoo-housed Greater Rhea females (Rhea americana) bred under similar rearing conditions during two breeding seasons to characterize concentration and distribution of maternal yolk progesterone. After high-performance liquid chromatography analysis, yolk hormone was measured using a commercial electrochemiluminescence immunoassay. Progesterone concentrations were found to vary significantly among the yolk layers, supporting a follicular origin for this steroid in Greater Rhea eggs. Additionally, highly similar mean absolute yolk progesterone concentrations were detected between 2013 and 2015 breeding seasons (1,332.98 ± 82.59 and 1,313.59 ± 85.19 ng/g, respectively). These values are also comparable to those found in some domestic carinate species. Findings suggest that at population level, when rearing conditions are similar, mean absolute yolk maternal progesterone concentrations also appear bounded. Future research on the factors and mechanisms that regulate progesterone deposition in Greater Rhea eggs is needed to better understand whether its levels depend on different rearing conditions.
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Affiliation(s)
- Natalia Soledad Della Costa
- Instituto de Diversidad y Ecología Animal (IDEA, CONICET-UNC) and Centro de Zoología Aplicada, Facultad de Ciencias Exactas Físicas y Naturales, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Joaquín Luis Navarro
- Instituto de Diversidad y Ecología Animal (IDEA, CONICET-UNC) and Centro de Zoología Aplicada, Facultad de Ciencias Exactas Físicas y Naturales, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Juan Manuel Busso
- Instituto de Investigaciones Biológicas y Tecnológicas, Instituto de Ciencia y Tecnología de los Alimentos (IIBYT, CONICET-UNC), Córdoba, Argentina
| | - Raúl Héctor Marin
- Instituto de Investigaciones Biológicas y Tecnológicas, Instituto de Ciencia y Tecnología de los Alimentos (IIBYT, CONICET-UNC), Córdoba, Argentina.,Cátedra de Química Biológica, Facultad de Ciencias Exactas, Físicas y Naturales, Universidad Nacional de Córdoba
| | - Mónica Beatriz Martella
- Instituto de Diversidad y Ecología Animal (IDEA, CONICET-UNC) and Centro de Zoología Aplicada, Facultad de Ciencias Exactas Físicas y Naturales, Universidad Nacional de Córdoba, Córdoba, Argentina
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9
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Murray CM, Merchant M, Easter M, Padilla S, Garrigós DB, Sasa Marin M, Guyer C. Detection of a synthetic sex steroid in the American crocodile (Crocodylus acutus): Evidence for a novel environmental androgen. CHEMOSPHERE 2017; 180:125-129. [PMID: 28399454 DOI: 10.1016/j.chemosphere.2017.04.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 04/03/2017] [Accepted: 04/04/2017] [Indexed: 06/07/2023]
Abstract
Endocrine-disrupting contaminants (EDC's) are well known to alter sexual differentiation among vertebrates via estrogenic effects during development, particularly in organisms characterized by temperature-dependent sex determination. However, substances producing androgenic effects typically lack potency when tested in laboratory settings and are virtually unstudied in field settings. Here, we assay levels of a synthetic androgen, 17α-methyltestosterone (MT), in a heavily male-biased population of American crocodiles in the Tempisque River Basin of Costa Rica based on the recent hypothesis that this chemical is an EDC in developing crocodilian embryos. The presence of MT was documented in all field-collected samples of egg yolk and in plasma of all age classes in among population of crocodiles. Hatchlings exhibited higher plasma MT concentrations (102.1 ± 82.8 ng/mL) than juveniles (33.8 ± 51.5) and adults (25.9 ± 20.8 ng/mL). Among populations, crocodiles captured in the Tempisque River (62.9 ± 73.7 ng/mL) were higher in MT concentration than those from Tarcoles (13.3 ± 11.4 ng/mL) and negative controls (0.001 ± 0.0002 ng/mL). A mechanism for the bio-transport of MT and its subsequent effects is proposed.
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Affiliation(s)
- Christopher M Murray
- Department of Biology, Tennessee Technological University, PO Box 5063, Cookeville, TN 38505, USA.
| | - Mark Merchant
- Department of Chemistry, McNeese State University, Lake Charles, LA, USA.
| | | | - Sergio Padilla
- Palo Verde Biological Station, Organization for Tropical Studies, Guanacaste, Costa Rica.
| | - Davinia B Garrigós
- Biodiversity and Evolutionary Biology "Cavanilles" Institute, University of Valencia, Valencia, Spain.
| | - Mahmood Sasa Marin
- Palo Verde Biological Station, Organization for Tropical Studies, Guanacaste, Costa Rica; Instituto Clodomiro Picado, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa Rica.
| | - Craig Guyer
- Department of Biological Sciences, Auburn University, 331 Funchess Hall, Auburn, AL 36849, USA.
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10
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Paitz RT, Bukhari SA, Bell AM. Stickleback embryos use ATP-binding cassette transporters as a buffer against exposure to maternally derived cortisol. Proc Biol Sci 2016; 283:20152838. [PMID: 26984623 DOI: 10.1098/rspb.2015.2838] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Offspring from females that experience stressful conditions during reproduction often exhibit altered phenotypes and many of these effects are thought to arise owing to increased exposure to maternal glucocorticoids. While embryos of placental vertebrates are known to regulate exposure to maternal glucocorticoids via placental steroid metabolism, much less is known about how and whether egg-laying vertebrates can control their steroid environment during embryonic development. We tested the hypothesis that threespine stickleback (Gasterosteus aculeatus) embryos can regulate exposure to maternal steroids via active efflux of maternal steroids from the egg. Embryos rapidly (within 72 h) cleared intact steroids, but blocking ATP-binding cassette (ABC) transporters inhibited cortisol clearance. Remarkably, this efflux of cortisol was sufficient to prevent a transcriptional response of embryos to exogenous cortisol. Taken together, these findings suggest that, much like their placental counterparts, developing fish embryos can actively regulate their exposure to maternal cortisol. These findings highlight the fact that even in egg-laying vertebrates, the realized exposure to maternal steroids is mediated by both maternal and embryonic processes and this has important implications for understanding how maternal stress influences offspring development.
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Affiliation(s)
- Ryan T Paitz
- School of Integrative Biology, University of Illinois, Urbana, IL 61801, USA School of Biological Sciences, Illinois State University, Campus Box 4120, Normal, IL 61790, USA
| | - Syed Abbas Bukhari
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, IL 61801, USA Illinois Informatics Institute, University of Illinois, Urbana, IL 61801, USA
| | - Alison M Bell
- School of Integrative Biology, University of Illinois, Urbana, IL 61801, USA Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, IL 61801, USA
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11
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Schmaltz G, Quinn JS, Schoech SJ. Maternal corticosterone deposition in avian yolk: Influence of laying order and group size in a joint-nesting, cooperatively breeding species. Gen Comp Endocrinol 2016; 232:145-50. [PMID: 27118704 DOI: 10.1016/j.ygcen.2016.04.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Revised: 03/04/2016] [Accepted: 04/22/2016] [Indexed: 11/23/2022]
Abstract
Glucocorticoid hormones play a key role in day-to-day adjustments to fluctuating metabolic needs. These hormones also mediate physiological and behavioral responses to stressful events, allowing individuals to cope with stressors. Various environmental insults, such as a food shortages, predation attempts, and agonistic encounters often elevate plasma glucocorticoid levels in vertebrates. Because exposure to maternally-derived (via circulation or egg) glucocorticoids may be detrimental to the developing embryo, maternal stress can have negative carryover effects on offspring fitness. We examined corticosterone, the primary avian glucocorticoid, concentrations in egg yolk in a plural-breeding, joint-nesting species, the smooth-billed ani (Crotophaga ani), in which females compete among themselves to lay eggs in the final incubated clutch. We investigated whether yolk corticosterone levels varied with laying order and group size. Because egg-laying competition leads to physiological and social stress that is intensified with group size and laying order, we predicted that yolk corticosterone levels should increase from the early to the late egg-laying period and from single female to multi-female groups. In this two-year field study, we found that yolk corticosterone levels of late-laid eggs within the communal clutch were higher in multi-female groups than in single female groups. Results from this study suggest that laying females experience higher levels of stress in multi-female groups and that this maternal stress influences yolk corticosterone concentrations. This study identifies a novel cost of group-living in plural-breeding cooperatively breeding birds, namely an increase in yolk corticosterone levels with group size that may result in detrimental effects on offspring development.
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Affiliation(s)
- Gregory Schmaltz
- McMaster University, Department of Biology, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada; University of the Fraser Valley, Department of Biology, 33844 King Road, Abbotsford, BC V2S 7M8, Canada.
| | - James S Quinn
- McMaster University, Department of Biology, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada
| | - Stephan J Schoech
- University of Memphis, Department of Biological Sciences, 3774 Walker Avenue, Memphis, TN 38152-3560, USA
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12
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Paitz RT, Mommer BC, Suhr E, Bell AM. Changes in the concentrations of four maternal steroids during embryonic development in the threespined stickleback (Gasterosteus aculeatus). JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL GENETICS AND PHYSIOLOGY 2015; 323:422-9. [PMID: 26036752 PMCID: PMC5977982 DOI: 10.1002/jez.1937] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 03/12/2015] [Accepted: 04/09/2015] [Indexed: 11/07/2022]
Abstract
Embryonic exposure to steroids often leads to long-term phenotypic effects. It has been hypothesized that mothers may be able to create a steroid environment that adjusts the phenotypes of offspring to current environmental conditions. Complicating this hypothesis is the potential for developing embryos to modulate their early endocrine environment. This study utilized the threespined stickleback (Gasterosteus aculeatus) to characterize the early endocrine environment within eggs by measuring four steroids (progesterone, testosterone, estradiol, and cortisol) of maternal origin. We then examined how the concentrations of these four steroids changed over the first 12 days post fertilization (dpf). Progesterone, testosterone, estradiol, and cortisol of maternal origin could be detected within unfertilized eggs and levels of all four steroids declined in the first 3 days following fertilization. While levels of progesterone, testosterone, and estradiol remained low after the initial decline, levels of cortisol rose again by 8 dpf. These results demonstrate that G. aculeatus embryos begin development in the presence of a number of maternal steroids but levels begin to change quickly following fertilization. This suggests that embryonic processes change the early endocrine environment and hence influence the ability of maternal steroids to affect development. With these findings, G. aculeatus becomes an intriguing system in which to study how selection may act on both maternal and embryonic processes to shape the evolutionary consequence of steroid-mediated maternal effects.
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Affiliation(s)
- Ryan Thomas Paitz
- School of Integrative Biology, Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois
- School of Biological Sciences, Illinois State University, Normal, Illinois
| | - Brett Christian Mommer
- School of Integrative Biology, Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois
- GIGA Neurosciences, University of Liege, Liège, Belgium
| | - Elissa Suhr
- School of Integrative Biology, Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois
| | - Alison Marie Bell
- School of Integrative Biology, Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois
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13
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Paitz RT, Bowden RM. The in ovo conversion of oestrone to oestrone sulfate is rapid and subject to inhibition by Bisphenol A. Biol Lett 2015; 11:20140946. [PMID: 25904318 PMCID: PMC4424608 DOI: 10.1098/rsbl.2014.0946] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 03/31/2015] [Indexed: 01/06/2023] Open
Abstract
Vertebrate embryos develop in the presence of maternally derived steroids. While these steroids can influence development, embryonic enzymes are thought to buffer some steroid sensitive processes, such as gonadal differentiation, from the effects of maternal steroids. Many of these same enzymes may also buffer the embryo from chemicals present in the environment, but this may alter their capacity to metabolize maternal steroids. Here, we characterized the ability of red-eared slider (Trachemys scripta) embryos to metabolize oestrone immediately following oviposition and tested whether a prevalent environmental chemical, Bisphenol A (BPA), would affect the in ovo conversion of oestrone to oestrone sulfate. We found that tritiated oestrone applied at the time of oviposition is mostly converted to oestrone sulfate within 6 h. However, when BPA is present, that conversion is inhibited, resulting in elevated oestrone levels. Our finding of rapid in ovo metabolism of steroids suggests that maternally derived enzymes are present in the egg and can alter embryonic exposure to exogenous chemicals. The disruption of this metabolism by BPA demonstrates how environmental chemicals might change embryonic exposure to endogenous substances within the egg. Taken together, these findings highlight the dynamic nature of the early endocrine environment in developing vertebrates.
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Affiliation(s)
- Ryan T Paitz
- School of Biological Sciences, Illinois State University, Campus Box 4120, Normal, IL 61790-4120, USA
| | - Rachel M Bowden
- School of Biological Sciences, Illinois State University, Campus Box 4120, Normal, IL 61790-4120, USA
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Paitz RT, Casto JM. The decline in yolk progesterone concentrations during incubation is dependent on embryonic development in the European starling. Gen Comp Endocrinol 2012; 176:415-9. [PMID: 22210246 DOI: 10.1016/j.ygcen.2011.12.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Accepted: 12/12/2011] [Indexed: 11/18/2022]
Abstract
Oviparous amniotes, particularly birds, have become model systems in which to study how mothers may utilize steroids to adaptively adjust offspring development. Although there is now ample evidence that maternally derived steroids in the egg at oviposition can influence offspring phenotype, very little is known about how these steroids elicit such effects. Of the major avian steroid hormones found in yolk, progesterone is by far the most abundant at oviposition, but has received little research attention to date. In this study, we examine the metabolism of [(3)H]-progesterone injected into freshly laid European starling eggs throughout the first 5 days of development by characterization of radioactivity within the egg homogenate. We also introduce a technique that utilizes a focal, freeze/thaw cycle to prevent embryonic development and allows us to assess the role of the embryo in metabolizing progesterone during early incubation. Two major findings result. First is that [(3)H]-progesterone is metabolized in eggs possessing a developing embryo, but not in eggs with disrupted embryonic development. Second is that the change in the distribution of radioactivity within eggs possessing an embryo is the result of metabolism of [(3)H]-progesterone to a more polar form that is subsequently conjugated. Together, these data suggest live embryos are necessary for metabolism of progesterone during early incubation, underscoring the potentially important contribution of embryos to functional modulation or mediation of maternal yolk steroid effects.
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Affiliation(s)
- Ryan T Paitz
- School of Biological Sciences, Campus Box 4120, Illinois State University, Normal, IL 61790-4120, USA.
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15
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Paitz RT, Sawa AR, Bowden RM. Characterizing the metabolism and movement of yolk estradiol during embryonic development in the red-eared slider (Trachemys scripta). Gen Comp Endocrinol 2012; 176:507-12. [PMID: 22033221 DOI: 10.1016/j.ygcen.2011.10.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Accepted: 10/12/2011] [Indexed: 11/17/2022]
Abstract
Eggs of oviparous amniotes can contain substantial quantities of several steroids at the time of oviposition. These maternally derived steroids appear to affect the phenotype of developing offspring, but not all steroid sensitive traits are affected by maternal steroids, and little is known about how these effects may arise. In this study, we applied tritiated estradiol to the eggs of red-eared sliders (Trachemys scripta) at the time of oviposition and characterized the subsequent metabolism and movement throughout embryonic development. Results indicate that very early in development, estradiol is converted to a variety of water-soluble estrogen sulfates that reside in the yolk and extraembryonic fluids until late in development. Within the final stages of development, we observe a significant decline in the total amount of metabolites present in the yolk and extraembryonic fluids and a significant increase in the amount of metabolites present in the embryo. While estradiol metabolism occurs during the early stages of development, the later stages appear to be the most dynamic with regards to the movement of estradiol metabolites. Our findings have important implications for studies investigating the effect of maternally derived steroids on offspring development.
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Affiliation(s)
- Ryan T Paitz
- School of Biological Sciences, Campus Box 4120, Illinois State University, Normal, IL 61790-4120, USA.
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Uller T, Helanterä H. From the origin of sex-determining factors to the evolution of sex-determining systems. QUARTERLY REVIEW OF BIOLOGY 2011; 86:163-80. [PMID: 21954700 DOI: 10.1086/661118] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Sex determination is typically classified as either genotypic or environmental. However, this dichotomy obscures the developmental origin and evolutionary modification of determinants of sex, and therefore hinders an understanding of the processes that generates diversity in sex-determining systems. Recent research on reptiles and fish emphasizes that sex determination is a multifactorial regulatory process that is best understood as a threshold dichotomy rather than as the result of genetically inherited triggers of development. Here we critically assess the relationship between the developmental origin of sex-determining factors and evolutionary transitions in sex-determining systems. Our perspective emphasizes the importance of both genetic and nongenetic causes in evolution of sex determination and may help to generate predictions with respect to the evolutionary patterns of sex-determining systems and the underlying diversity of developmental and genetic regulatory networks.
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Affiliation(s)
- Tobias Uller
- Edward Grey Institute, Department of Zoology, University of Oxford Oxford OX1 3PS United Kingdom.
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Paitz RT, Bowden RM. Biological activity of oestradiol sulphate in an oviparous amniote: implications for maternal steroid effects. Proc Biol Sci 2011; 278:2005-10. [PMID: 21106590 PMCID: PMC3107646 DOI: 10.1098/rspb.2010.2128] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Accepted: 11/05/2010] [Indexed: 11/12/2022] Open
Abstract
Understanding the many factors that underlie phenotypic variation is of profound importance to evolutionary biologists. The embryonic endocrine environment is one such factor that has received much attention. In placental amniotes, the dynamic interaction of maternal and embryonic steroid production and metabolism is critical to regulating the endocrine environment. Less is known about how embryos of oviparous amniotes regulate their endocrine environment because most studies have focused on relating initial steroid levels in the yolk at oviposition to offspring phenotype. We tested the hypothesis that embryos of oviparous amniotes regulate their endocrine environment by conjugating maternal steroids and subsequently using the metabolites as precursors for steroid production later in development. Using the red-eared slider turtle (Trachemys scripta), we first characterized the conjugation of exogenous oestradiol to either oestradiol glucuronide or oestradiol sulphate (E(2)-S) in ovo during the first 15 days of development. Results show that oestradiol is primarily conjugated to E(2)-S. We then examined whether E(2)-S influenced sex determination and report that E(2)-S increases the production of female offspring. These data demonstrate that oviparous amniotes can both sulphonate steroids and respond to sulphonated steroids during embryonic development in a manner similar to placental amniotes.
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Affiliation(s)
- Ryan T Paitz
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA.
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Paitz RT, Bowden RM, Casto JM. Embryonic modulation of maternal steroids in European starlings (Sturnus vulgaris). Proc Biol Sci 2010; 278:99-106. [PMID: 20667883 DOI: 10.1098/rspb.2010.0813] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In birds, maternally derived yolk steroids are a proposed mechanism by which females can adjust individual offspring phenotype to prevailing conditions. However, when interests of mother and offspring differ, parent-offspring conflict will arise and embryonic interests, not those of the mother, should drive offspring response to maternal steroids in eggs. Because of this potential conflict, we investigated the ability of developing bird embryos to process maternally derived yolk steroids. We examined how progesterone, testosterone and oestradiol levels changed in both the yolk/albumen (YA) and the embryo of European starling eggs during the first 10 days of development. Next, we injected tritiated testosterone into eggs at oviposition to characterize potential metabolic pathways during development. Ether extractions separated organic and aqueous metabolites in both the embryo and YA homogenate, after which major steroid metabolites were identified. Results indicate that the concentrations of all three steroids declined during development in the YA homogenate. Exogenous testosterone was primarily metabolized to an aqueous form of etiocholanolone that remained in the YA. These results clearly demonstrate that embryos can modulate their local steroid environment, setting up the potential for parent-offspring conflict. Embryonic regulation must be considered when addressing the evolutionary consequences of maternal steroids in eggs.
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Affiliation(s)
- Ryan T Paitz
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA.
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