Telomere-Related Gene Networks in the Ovary Shift Across Environmental Factors

The ovary is key to linking environmental factors with the timing and quality of offspring development. Focused on free-living female tree swallows (Tachycineta bicolor), we measured temporal variation in ovarian expression of genes involved in the regulation of telomere length. Using qPCR, we quantified mRNA abundance of shelterin proteins (TERF1, TERF2, TERF2IP, TPP1, POT1), telomerase (TERT), antioxidants (SOD1, PRDX-1, GPX), and glucocorticoid receptors (MR, GR). We asked how they differ across breeding stages and social environments, and then we assessed effects on gene co-expression, which reflects coordinated changes across this network of interacting genes. We hypothesized that maintenance of telomeres is upregulated and more strongly coregulated in the lead up to reproduction, i.e., before egg-laying and following a social challenge. We did not find a main effect of environmental context on mRNA abundance, but we did detect subtle differences in gene co-expression networks. Females exhibited stronger coregulation among shelterin proteins and stronger crosstalk with glucocorticoid receptors during incubation. In response to a conspecific challenger, coregulation of antioxidants with shelterin and glucocorticoid receptors was weaker or more negatively correlated, suggesting semi-independent social modulation of these telomere regulatory networks. While the consequences of these transcriptional differences require more research, our results suggest that the environment could contribute to protection of the ovary, including its telomeres.