Seasonal and flight-related variation of galectin expression in heart, liver and flight muscles of yellow-rumped warblers (Setophaga coronata).

Galectins, a family of multifunctional glycan-binding proteins, are proposed as biomarkers of cellular stress responses. Avian migration is an energetically challenging physical stress, which represents a physiological model of muscular endurance exercises. This study assesses change in galectin gene expression profiles associated with seasonal variation in migratory state and endurance flight in yellow-rumped warblers (Setophaga coronata). Bioinformatics analysis and real-time qPCR were used to analyse the expression of galectins in flight muscle, heart and liver tissues of 15 warblers separated into three groups of winter unflown, and fall migratory flown/unflown birds. Five transcripts similar to chicken and human galectins -1, -2, -3, -4, and -8 were identified in warbler tissues. The expression of these galectins showed no seasonal changes between two experimental groups of birds maintained under unflown winter and fall conditions indicating a minor role of galectins in preparation for migration. However, endurance flight led to a significant elevation of galectin-1 and galectin-3 mRNAs in flight muscles and galectin-3 mRNA in heart tissue while no changes were observed in liver. Different changes were observed for the level of O-GlcNAcylated proteins, which were elevated in flight muscles under winter conditions. These results suggest that secreted galectin-1 and galectin-3 may be active in repair of bird muscles during and following migratory flight and serve as molecular biomarkers of recent arrival from migratory flights in field studies.