title: Exogenous estradiol alters gonadal growth and timing of temperature sex determination in gonads of sea turtle.
abstract: Temperature sex determining species offer a model for investigating how environmental cues become integrated to the regulation of patterning genes and growth, among bipotential gonads. Manipulation of steroid hormones has revealed the important role of aromatase in the regulation of the estrogen levels involved in temperature-dependent sex determination. Estradiol treatment counteracts the effect of male-promoting temperature, but the resulting ovarian developmental pattern differs from that manifested with the female-promoting temperature. Hypoplastic gonads have been reported among estradiol-treated turtles; however the estradiol effect on gonadal size has not been examined. Here we focused on the sea turtle Lepidochelys olivacea, which develops hypoplastic gonads with estradiol treatment. We studied the effect of estradiol on cell proliferation and on candidate genes involved in ovarian pattern. We found this effect is organ specific, causing a dramatic reduction in gonadal cell proliferation during the temperature-sensitive period. Although the incipient gonads resembled tiny ovaries, remodeling of the medullary cords and down-regulation of testicular factor Sox9 were considerably delayed. Contrastingly, with ovarian promoting temperature as a cue, exogenous estradiol induced the up-regulation of the ovary factor FoxL2, prior to the expression of aromatase. The strong expression of estrogen receptor alpha at the time of treatment suggests that it mediates estradiol effects. Overall results indicate that estradiol levels required for gonadal growth and to establish the female genetic network are delicately regulated by temperature.
authors.affiliation: Departamento de Embriología, Facultad de Medicina. Universidad Nacional Autónoma de México, Mexico City, Mexico. Electronic address: roveazdih@yahoo.com.mx.
authors.forename: Verónica
authors.initials: V
authors.lastname: Díaz-Hernández
authors.affiliation: Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas. Universidad Nacional Autónoma de México, Mexico City, Mexico. Electronic address: alemarmol@biomedicas.unam.mx.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Marmolejo-Valencia
authors.affiliation: Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas; Universidad Nacional Autónoma de México. Ciudad Universitaria, CP. 04510, México DF, Mexico City, Mexico. Electronic address: merchant@unam.mx.
authors.forename: Horacio
authors.initials: H
authors.lastname: Merchant-Larios
mesh_terms: D000818:Animals; D001141:Aromatase / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D004625:Embryo, Nonmammalian / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D005455:Fluorescent Antibody Technique; D051858:Forkhead Transcription Factors / Q000378:metabolism; D005629:Frozen Sections; D006066:Gonads / Q000187:drug effects / Q000254:growth & development* / Q000502:physiology* / Q000648:ultrastructure; D008297:Male; D008954:Models, Biological; D009928:Organ Specificity / Q000187:drug effects; D010053:Ovary / Q000187:drug effects / Q000502:physiology; D019849:Sex Determination Processes / Q000187:drug effects*; D012733:Sex Differentiation / Q000187:drug effects; D013696:Temperature; D013737:Testis / Q000187:drug effects / Q000502:physiology; D013997:Time Factors; D014426:Turtles / Q000502:physiology*
chemical_list: D051858:Forkhead Transcription Factors; D004958:Estradiol; D001141:Aromatase
keywords: Aromatase; Estradiol; FoxL2; Gonadal growth; Sex determination; Turtle