title: Period coding of Bmal1 oscillators in the suprachiasmatic nucleus.
abstract: Circadian oscillators in the suprachiasmatic nucleus (SCN) collectively orchestrate 24 h rhythms in the body while also coding for seasonal rhythms. Although synchronization is required among SCN oscillators to provide robustness for regular timekeeping (Herzog et al., 2004), heterogeneity of period and phase distributions is needed to accommodate seasonal variations in light duration (Pittendrigh and Daan, 1976b). In the mouse SCN, the heterogeneous phase distribution has been recently found in the cycling of clock genes Period 1 and Period 2 (Per1, Per2) and has been shown to reorganize by relative day lengths (Inagaki et al., 2007). However, it is not yet clearly understood what underlies the spatial patterning of Per1 and Per2 expression (Yamaguchi et al., 2003; Foley et al., 2011) and its plasticity. We found that the period of the oscillation in Bmal1 expression, a positive-feedback component of the circadian clock, preserves the behavioral circadian period under culture and drives clustered oscillations in the mouse SCN. Pharmacological and physical isolations of SCN subregions indicate that the period of Bmal1 oscillation is subregion specific and is preserved during culture. Together with computer simulations, we show that either the intercellular coupling does not strongly influence the Bmal1 oscillation or the nature of the coupling is more complex than previously assumed. Furthermore, we have found that the region-specific periods are modulated by the light conditions that an animal is exposed to. Based on these, we suggest that the period forms the basis of seasonal coding in the SCN.
authors: Osaka Bioscience Institute, Suita, Osaka 565-0874, Japan.
authors: Jihwan
authors: J
authors: Myung
authors: Sungho
authors: S
authors: Hong
authors: Fumiyuki
authors: F
authors: Hatanaka
authors: Yoshihiro
authors: Y
authors: Nakajima
authors: Erik
authors: E
authors: De Schutter
authors: Toru
authors: T
authors: Takumi
mesh_terms: D056930:ARNTL Transcription Factors / Q000235:genetics / Q000378:metabolism*; D000200:Action Potentials / Q000187:drug effects / Q000235:genetics; D000818:Animals; D001683:Biological Clocks / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D001931:Brain Mapping; D002940:Circadian Rhythm / Q000187:drug effects / Q000235:genetics*; D016000:Cluster Analysis; D018756:GABA Antagonists / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000235:genetics; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008959:Models, Neurological; D009043:Motor Activity / Q000235:genetics; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D017711:Nonlinear Dynamics; D009924:Organ Culture Techniques; D056950:Period Circadian Proteins / Q000235:genetics / Q000378:metabolism; D017440:Photoperiod; D011724:Pyridazines / Q000494:pharmacology; D026941:Sodium Channel Blockers / Q000494:pharmacology; D012984:Software; D013223:Statistics as Topic; D013493:Suprachiasmatic Nucleus / Q000166:cytology / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D056930:ARNTL Transcription Factors; C538961:Bmal1 protein, mouse; D018756:GABA Antagonists; D008164:Luminescent Proteins; D056950:Period Circadian Proteins; D011724:Pyridazines; D026941:Sodium Channel Blockers; D013779:Tetrodotoxin; C049853:gabazine