A1 Refereed original research article in a scientific journal

From maternal glucocorticoid and thyroid hormones to epigenetic regulation of offspring gene expression: An experimental study in a wild bird species




AuthorsHukkanen Mikaela, Hsu Bin-Yan, Cossin-Sevrin Nina, Crombecque Mélanie, Delaunay Axelle, Hollmen Lotta, Kaukonen Riina, Konki Mikko, Lund Riikka, Marciau Coline, Stier Antoine, Ruuskanen Suvi

PublisherJohn Wiley and Sons Inc

Publication year2023

JournalEvolutionary Applications

Journal name in sourceEvolutionary Applications

Volume16

Issue10

First page 1753

Last page1769

eISSN1752-4571

DOIhttps://doi.org/10.1111/eva.13598

Web address https://doi.org/10.1111/eva.13598

Self-archived copy’s web addresshttps://research.utu.fi/converis/portal/detail/Publication/181495037


Abstract

Offspring phenotype at birth is determined by its genotype and the prenatal environment including exposure to maternal hormones. Variation in both maternal glucocorticoids and thyroid hormones can affect offspring phenotype, but the underlying molecular mechanisms, especially those contributing to long-lasting effects, remain unclear. Epigenetic changes (such as DNA methylation) have been postulated as mediators of long-lasting effects of early-life environment. In this study, we determined the effects of elevated prenatal glucocorticoid and thyroid hormones on handling stress response (breath rate) as well as DNA methylation and gene expression of glucocorticoid receptor (GR) and thyroid hormone receptor (THR) in great tits (Parus major). Eggs were injected before incubation onset with corticosterone (the main avian glucocorticoid) and/or thyroid hormones (thyroxine and triiodothyronine) to simulate variation in maternal hormone deposition. Breath rate during handling and gene expression of GR and THR were evaluated 14 days after hatching. Methylation status of GR and THR genes was analyzed from the longitudinal blood cells sampled 7 and 14 days after hatching, as well as the following autumn. Elevated prenatal corticosterone level significantly increased the breath rate during handling, indicating an enhanced metabolic stress response. Prenatal corticosterone manipulation had CpG-site-specific effects on DNA methylation at the GR putative promoter region, while it did not significantly affect GR gene expression. GR expression was negatively associated with earlier hatching date and chick size. THR methylation or expression did not exhibit any significant relationship with the hormonal treatments or the examined covariates, suggesting that TH signaling may be more robust due to its crucial role in development. This study provides some support to the hypothesis suggesting that maternal corticosterone may influence offspring metabolic stress response via epigenetic alterations, yet their possible adaptive role in optimizing offspring phenotype to the prevailing conditions, context-dependency, and the underlying molecular interplay needs further research.


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