THE RESPONSE OF PER1 TO LIGHT IN THE SUPRACHIASMATIC NUCLEUS OF THE DIURNAL DEGU (OCTODON DEGUS)

Abstract

Several studies suggest that the circadian systems of diurnal mammals respond differently to daytime light than those of nocturnal mammals. We hypothesized that the photosensitive “clock” gene Per1 would respond to light exposure during subjective day in the suprachiasmatic nucleus of the diurnal rodent, Octodon degus. Tissue was collected 1.5–2 h after a 30 min light pulse presented at five timepoints across the 24 h day and compared to controls maintained under conditions of constant darkness. Per1 mRNA was quantified using in situ hybridization. Results showed that the rhythmicity and photic responsiveness of Per1 in the degu resembles that of nocturnal animals. (Author correspondence: [email protected])

Key Words:

• Diurnality
• Chronotype
• Per1
• Photic
• Day-active
• Clock gene

ACKNOWLEDGMENTS

The authors would like to thank Dr. Megan Mahoney for her constant guidance and support. The authors also thank Andy Vosko, Grace Fung, Anna de Caneva, Jenna Stelzer, Aimee Roby, and Andrea King for their help with tissue collection, slicing, and in situ hybridization. Finally, they acknowledge Kathy Gimson, Julie Stewlow, and Jim Donner for their work managing the degu colony. These investigations were supported by the National Science Foundation (TML, IBN-0212322), the Reproductive Science Program T32 Training Grant (MHH, HD07048), and the College of Literature, Science and Arts at University of Michigan Grant (TML).