Regulation of Seasonal Changes in Gene Expression via Adiponectin Signaling in a Migratory Bird Species

Restricted (Penn State Only)
Author:
Giossi, Joseph Thomas
Graduate Program:
Physiology
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
March 16, 2017
Committee Members:
  • Paul Bartell, Thesis Advisor
  • Kevin Harvatine, Committee Member
  • Joshua Lambert, Committee Member
  • Ramesh Ramachandran, Committee Member
Keywords:
  • clock
  • adiponectin
  • biological clock
  • sparrow
  • migration
Abstract:
Prior to migration, birds undergo a period hyperphagia, which serves to increase fat stores for energy-intensive flights. During migration, birds switch from a diurnal to a nocturnal activity cycle, which reduces stress associated with migration (e.g. thermal, dehydration, and predation). While it is widely understood that seasonal changes in behaviors are regulated by circadian and circannual changes in the biological clock, the mechanisms linking changes in the biological clock to changes in behavior remains unknown. My aim was to elucidate the effects of adiponectin on changes in clock and metabolic gene expression between the migrating and non-migrating states. Skeletal muscle tissue was harvested from White Throated Sparrows (Zonotrichia albicollis) and cultured in an organotypic culture system. Following treatment with adiponectin or vehicle at either ZT0 or 12, western blots and quantitative polymerase chain reaction (qPCR) were used to determine changes in adiponectin signaling and gene expression, respectively. Western blots displayed adiponectin-induced changes in abundance of pERK and AMPK. Several changes in adiponectin-induced gene expression for CLOCK, per3, casein kinase 2, FABPpm, HFABP, PPARα and PPARγ were noted. Changes in gene expression were notably different depending on migratory status and time of treatment. Our data suggest that adiponectin signaling can induce changes in expression of biological clock and metabolic genes, and that the pathways eliciting these changes may be different between the migrating and non-migrating life stages of birds.