title: Dimorphic DNA methylation during temperature-dependent sex determination in the sea turtle Lepidochelys olivacea.
abstract: Sex determination in vertebrates depends on the expression of a conserved network of genes. Sea turtles such as Lepidochelys olivacea have temperature-dependent sex determination. The present work analyses some of the epigenetic processes involved in this. We describe sexual dimorphism in global DNA methylation patterns between ovaries and testes of L. olivacea and show that the differences may arise from a combination of DNA methylation and demethylation events that occur during sex determination. Irrespective of incubation temperature, 5-hydroxymethylcytosine was abundant in the bipotential gonad; however, following sex determination, this modification was no longer found in pre-Sertoli cells in the testes. These changes correlate with the establishment of the sexually dimorphic DNA methylation patterns, down regulation of Sox9 gene expression in ovaries and irreversible gonadal commitment towards a male or female differentiation pathway. Thus, DNA methylation changes may be necessary for the stabilization of the gene expression networks that drive the differentiation of the bipotential gonad to form either an ovary or a testis in L. olivacea and probably among other species that manifest temperature-dependent sex determination.
authors.affiliation: Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, UNAM, México DF, México City, Mexico.
authors.forename: Daniela
authors.initials: D
authors.lastname: Venegas
authors.affiliation: Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, UNAM, México DF, México City, Mexico.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Marmolejo-Valencia
authors.affiliation: Departamento de Genética Molecular, Instituto de Fisiología Celular, UNAM, México DF, México City, Mexico.
authors.forename: Christian
authors.initials: C
authors.lastname: Valdes-Quezada
authors.affiliation: Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, UNAM, México DF, México City, Mexico; Departamento de Inmunología, Instituto de Investigaciones Biomédicas, UNAM, México DF, México City, Mexico.
authors.forename: Tzipe
authors.initials: T
authors.lastname: Govenzensky
authors.affiliation: Departamento de Genética Molecular, Instituto de Fisiología Celular, UNAM, México DF, México City, Mexico.
authors.forename: Félix
authors.initials: F
authors.lastname: Recillas-Targa
authors.affiliation: Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, UNAM, México DF, México City, Mexico. Electronic address: merchant@unam.mx.
authors.forename: Horacio
authors.initials: H
authors.lastname: Merchant-Larios
mesh_terms: D000818:Animals; D019175:DNA Methylation / Q000235:genetics*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006066:Gonads / Q000378:metabolism; D008297:Male; D019849:Sex Determination Processes / Q000235:genetics*; D013696:Temperature; D014426:Turtles / Q000502:physiology*
keywords: DNA methylation/demethylation; Gonadal development; Sea turtle; Spatiotemporal 5hmC; Temperature sex determination