Temperature Incubation Influences Gonadal Gene Expression during Leopard Gecko Development

SIMPLE SUMMARY: Environmental sex determination is a modality of sex determination related to external factors and that has implicated determinants such as climatic conditions, which act on the embryo after fertilization and deposition of the egg. For reptiles, the temperature is the main element for sex determination; this factor affects laid eggs in different ways. Details remain to be elucidated concerning the temporal gene expression and the functions of their protein products. Therefore, the aim of the present work was to determine the genetic determinants differentially represented during the embryonic development of a model species already known in temperature-dependent sex determination, the leopard gecko Eublepharis macularius. Following this investigation, new data were acquired on genes expressed in the sexual differentiation of E. macularius. In addition, new genes potentially involved in the mechanisms of tissue and metabolic sexual differentiation of the embryo of this species have been identified. This study could bring new useful information in order to correctly interpret the regulatory pathway underlying the determination of sex in vertebrates. ABSTRACT: During development, sexual differentiation results in physiological, anatomical and metabolic differences that implicate not only the gonads but also other body structures. Sex in Leopard geckos is determined by egg incubation temperature. Based on the premise that the developmental decision of gender does not depend on a single gene, we performed an analysis on E. macularius to gain insights into the genes that may be involved in gonads’ sexual differentiation during the thermosensitive period. All the genes were identified as differentially expressed at stage 30 during the labile phase of sex differentiation. In this way, the expression of genes known to be involved in gonadal sexual differentiation, such as WNT4, SOX9, DMRT1, Erα, Erβ, GnRH, P450 aromatase, PRL and PRL-R, was investigated. Other genes putatively involved in sex differentiation were sought by differential display. Our findings indicate that embryo exposure to a sex-determining temperature induces differential expression of several genes that are involved not only in gonadal differentiation, but also in several biological pathways (ALDOC, FREM1, BBIP1, CA5A, NADH5, L1 non-LTR retrotransposons, PKM). Our data perfectly fit within the new studies conducted in developmental biology, which indicate that in the developing embryo, in addition to gonadal differentiation, sex-specific tissue and metabolic polarization take place in all organisms.