GSE116989
Transcriptome Analyses of Heart and Liver Reveal Novel Pathways for Regulating Songbird Migration
Most migrating passerine birds undertake their long biannual voyages during the night. During these times of the year birds are in a continuous state of severe sleep restriction, yet curiously they perform as well, or better, on tests of physical and cognitive performance than during non-migrating times of the year. This inherent physiological protection, a component of the endogenous circannual program regulating this crucial life history stage, disappears when birds are forced to stay awake at other times of the year, demonstrating that these protective changes are only associated with the nocturnal migratory state. The goal of the current  study was to identify the physiological mechanisms that confer protection against the usually negative consequences of sleep loss while simultaneously allowing for the increased metabolic and cardiovascular output required for migration. To that end, we performed an RNA-seq analysis of heart and Liver collected from birds at different times of day under different migratory states and analyzed these data using differential expression, Ingenuity Pathway Analysis and Weighted Gene Co-expression Network Analysis. We identified numerous changes in gene expression networks implicating the involvement of multiple systems and pathways. These pathways regulate many aspects of metabolism, immune function, extracellular matrix wound repair, and protection of multiple organ systems in the body. Consequently, the circannual program controlling the appearance of the migratory phenotype involves the complex regulation of diverse gene networks associated with the physical demands of migration. Overall design: Examination of transcriptome in two tissues from white-throated sparrows (heart & liver), at two time points (ZT6 & ZT18), under two phenotypic conditions (migratory and non-migratory), with n=5/group, sequenced to ~40 million reads/sample, 100bp, single-end reads for quantification