title: Changes in the concentrations of four maternal steroids during embryonic development in the threespined stickleback (Gasterosteus aculeatus).
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.
authors.affiliation: 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.
authors.forename: Ryan Thomas
authors.initials: RT
authors.lastname: Paitz
authors.affiliation: School of Integrative Biology, Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois.|GIGA Neurosciences, University of Liege, Liège, Belgium.
authors.forename: Brett Christian
authors.initials: BC
authors.lastname: Mommer
authors.affiliation: School of Integrative Biology, Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois.
authors.forename: Elissa
authors.initials: E
authors.lastname: Suhr
authors.affiliation: School of Integrative Biology, Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois.
authors.forename: Alison Marie
authors.initials: AM
authors.lastname: Bell
mesh_terms: D000818:Animals; D004625:Embryo, Nonmammalian / Q000196:embryology*; D047108:Embryonic Development; D004703:Endocrine System / Q000196:embryology; D004958:Estradiol / Q000378:metabolism; D005260:Female; D012739:Gonadal Steroid Hormones / Q000378:metabolism*; D006854:Hydrocortisone / Q000378:metabolism; D008297:Male; D010063:Ovum / Q000737:chemistry; D011374:Progesterone / Q000378:metabolism; D023701:Smegmamorpha / Q000196:embryology / Q000378:metabolism*; D013739:Testosterone / Q000378:metabolism
chemical_list: D012739:Gonadal Steroid Hormones; D013739:Testosterone; D011374:Progesterone; D004958:Estradiol; D006854:Hydrocortisone