Meeting Abstract
113.4 Tuesday, Jan. 7 11:15 Molecular mechanisms of metabolic flexibility induced by synthetic, environmental cues in the Dark-eyed Junco (Junco hyemalis) STAGER, M*; SWANSON, D.L.; CHEVIRON, Z.A.; Univ. of Illinois at Urbana-Champaign; Univ. of South Dakota; Univ. of Illinois at Urbana-Champaign stager2@illinois.edu
Phenotypic plasticity is considered a driving force in evolution; environmental variation can induce transcriptional responses that enable an organism to adapt by flexibly altering its phenotype. Although vertebrate biology is replete with examples of profound phenotypic plasticity, very little is known about the mechanisms responsible for these changes in wild animals. In order to gain insight into the fundamental mechanisms of metabolic flexibility, we evaluated the effects of two environmental cues (photoperiod and temperature) on seasonal variation in metabolic performance and correlated differences in underlying gene expression profiles in Dark-eyed Juncos (Junco hyemalis). We exposed overwintering juncos (n = 40) to a 6-week acclimation trial with (a) short or long day lengths and (b) cold (3°C) or warm (24°C) temperatures. We quantified thermogenic capacity (cold-induced summit metabolic rate) and collected pectoralis tissue for RNA-sequencing and quantifying enzyme activity. We tested for differential gene expression (n = 1894 genes among treatments) and then identified modules of highly co-regulated genes associated with thermogenic capacity (n = 19 genes). These modules were enriched for terms associated with fatty acid metabolism and muscle contraction. We also tested the connection between transcriptomic and proteomic responses (using activities of key metabolic enzymes and associated transcript abundances) and found them to be correlated, suggesting that transcriptomic responses do indeed result in phenotypic effects; however, gene expression did not predict the abundance of gene products at a 1:1 ratio. These findings show that increased metabolic performance is due to simultaneous changes in genetically independent, but interacting hierarchical pathways.
