Role for androgens in determination of ovarian fate in the common snapping turtle, Chelydra serpentina

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    Abstract

    Sex steroids are involved in sex determination in almost all vertebrates, including species with temperature-dependent sex determination (TSD). It is well established that aromatase and estrogens are involved in ovary determination in TSD species. In contrast, the role of non-aromatizable androgens in TSD is less clear. In this study, we used dihydrotestosterone (DHT) and an antagonist of the mammalian androgen receptor (flutamide) to examine the impact of androgens on sex determination in the snapping turtle. We incubated eggs at a male-producing temperature and treated embryos with drug delivery vehicle (5 L ethanol), DHT in vehicle, or flutamide in vehicle during the sex-determining period. We then measured expression of markers for ovarian and testicular development and genes involved in steroidogenesis. A subset of embryos and hatchlings were collected for histological analysis of gonad differentiation and sex determination. DHT and flutamide both induced ovarian development: 100% of vehicle-treated hatchlings had testes, while 60% of DHT-treated and 32% flutamide-treated hatchlings had ovaries. DHT and flutamide treatments also had feminizing effects on gene expression patterns and the structure of embryonic gonads. DHT treatment increased expression of FoxL2, androgen receptor, aromatase and several steroidogenic genes. Flutamide produced a similar, but weaker, pattern of gene expression. Genes involved in testis development (Sox9 and Amh) were influenced by flutamide treatment. Our findings support the hypothesis that androgens and the androgen receptor are involved in ovary determination in the common snapping turtle.

    Original languageEnglish (US)
    Pages (from-to)7-16
    Number of pages10
    JournalGeneral and Comparative Endocrinology
    Volume281
    DOIs
    StatePublished - Sep 15 2019

    Bibliographical note

    Funding Information:
    Support for this work came from Grant 5R21HD049486 from the National Institute of Child Health and Human Development and National Science Foundation award IBN IOS-0923300 and IOS-1558034 to T. Rhen, and NSF EPSCoR Doctoral Dissertation Award #EPS-0814442 to A. Schroeder. The Office of Research Development and Compliance at the University of North Dakota also provided support through a Faculty Research Seed Money Grant to T. Rhen. Additional support was provided through the Esther Wadsworth Hall Wheeler Research Award to A. Schroeder. The authors wish to thank Heath Legge, Laurel Wessman, Ruby Fagerlie, and June Levin for their assistance with this work. We also wish to thank the Minnesota Department of Natural Resources for providing special permits for collection of snapping turtle eggs.

    Funding Information:
    Support for this work came from Grant 5R21HD049486 from the National Institute of Child Health and Human Development and National Science Foundation award IBN IOS-0923300 and IOS-1558034 to T. Rhen, and NSF EPSCoR Doctoral Dissertation Award #EPS-0814442 to A. Schroeder. The Office of Research Development and Compliance at the University of North Dakota also provided support through a Faculty Research Seed Money Grant to T. Rhen. Additional support was provided through the Esther Wadsworth Hall Wheeler Research Award to A. Schroeder. The authors wish to thank Heath Legge, Laurel Wessman, Ruby Fagerlie, and June Levin for their assistance with this work. We also wish to thank the Minnesota Department of Natural Resources for providing special permits for collection of snapping turtle eggs.

    Publisher Copyright:
    © 2019 Elsevier Inc.

    Keywords

    • Androgens
    • Dihydrotestosterone
    • Flutamide
    • Ovary
    • Temperature-dependent sex determination

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