title: Localization of circadian clock protein BMAL1 in the photoperiodic signal transduction machinery in Japanese quail.
abstract: The circadian clock is a fundamental property of living organisms and is involved in seasonal (photoperiodic) time measurement. Among vertebrates, birds have multiple circadian pacemakers in the eye, the pineal gland, and the suprachiasmatic nucleus (SCN), and have highly sophisticated photoperiodic mechanisms. However, because the removal of these circadian pacemakers fails to abolish the photoperiodic response, the existence of another "photoperiodic clock" has been suggested. Recent studies have revealed that the mediobasal hypothalamus (MBH) and the adjacent pars tuberalis (PT) of the pituitary gland constitute key components of the photoperiodic signal transduction machinery. In the present study, we generated a polyclonal antibody against the chicken circadian clock protein BMAL1 to examine BMAL1 distribution in the Japanese quail brain by using immunohistochemistry. BMAL1-like immunoreactivity (lir) was confirmed in the pineal gland and the medial SCN, which are critical circadian pacemakers. We also observed strong immunoreactivity in the MBH, including the ependymal cells (ECs), the infundibular nucleus (IN), the median eminence (ME), and the adjacent PT. Furthermore, semiquantitative analysis suggested that BMAL1-lir shows daily fluctuation in these regions. It is possible that circadian clocks in the photoperiodic signal transduction machinery such as the PT and the EC may be involved in the regulation of photoperiodism.
authors.affiliation: Laboratory of Animal Physiology, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Ikegami
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Katou
authors.forename: Kumiko
authors.initials: K
authors.lastname: Higashi
authors.forename: Takashi
authors.initials: T
authors.lastname: Yoshimura
mesh_terms: D056930:ARNTL Transcription Factors / Q000276:immunology / Q000378:metabolism*; D000818:Animals; D000906:Antibodies / Q000378:metabolism; D001111:Arcuate Nucleus of Hypothalamus / Q000378:metabolism; D030161:Avian Proteins / Q000276:immunology / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D002645:Chickens / Q000378:metabolism*; D003370:Coturnix / Q000378:metabolism*; D007031:Hypothalamus / Q000378:metabolism; D008297:Male; D008473:Median Eminence / Q000378:metabolism; D010507:Periodicity; D017440:Photoperiod; D010870:Pineal Gland / Q000378:metabolism; D013045:Species Specificity; D013493:Suprachiasmatic Nucleus / Q000378:metabolism; D013997:Time Factors
chemical_list: D056930:ARNTL Transcription Factors; D000906:Antibodies; D030161:Avian Proteins