Meeting Abstract
We investigated the role of temperature in photoperiodic regulation of seasonal processes in migratory redheaded buntings (Emberiza bruniceps), which is photosensitive and responds to long photoperiods. Buntings were exposed to long photoperiod (13L:11D) for 7 or 19 days at low (22˚± 2˚C) or high (38˚± 2˚C) temperature, with a group maintained on non-inductive short photoperiod (8L: 16D). Birds showed the initiation of body fattening and testis growth under long, but not short, photoperiod. Further, we measured the expression of genes involved in thermal sensation (trpv4, trpm8, bdnf, adcyap1), lipid regulation (lpl) and epigenetic modifications (dnmt3a, dnmt3b, tet2, hat1) in the hypothalamus, in fatty acid metabolism (elovl6, scd, dgat2, srebf1, fads2) in the liver, and in fatty acid transport (cd36, fabp3), response to hypoxia (hif1α) and muscular strength (myod) in the muscle. We found both photoperiod and temperature effects on mRNA expression levels, although with gene- and/ or tissue specific differences. Hypothalamic expression of dnmt3b and tet2 genes was altered by the photoperiod, and of trpm8 by the temperature. While elovl6, dgat2, scd, srebf1 expressions were affected by photoperiod and/or temperature in the liver, cd36 and fabp3 expressions were affected by temperature in the muscle. These results show molecular changes in response to both photoperiod and temperature, and give insights how possibly temperature might modulate the photoperiod-induced seasonal responses in migratory species.
