1. Division of Biomodelling, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
2. Functional Genomics Subunit, Centre for Developmental Biology, RIKEN, 2-3-3 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047, Japan
3. Department of Applied Biochemistry, Faculty of Agriculture, Utsunomiya University, 350 Mine-machi, Utsunomiya, 321-8505, Japan
4. Division of Genetics and Genomics, Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Roslin, Midlothian EH25 9PS, UK
5. Laboratory of Comparative Biochemistry, Graduate School of Applied Biological Sciences, Gifu University, Gifu 501-1193, Japan
6. Department of Medical Genome Sciences, Graduate School of Frontier Sciences, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
7. Division of Biofunctions Development, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
8. Avian Bioscience Research Centre, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
9. Laboratory for Systems Biology, Centre for Developmental Biology, RIKEN, 2-3-3 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047, Japan
10. Institute for Advanced Research, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
11. These authors contributed equally to this work.

Correspondence to: Takashi Yoshimura^1,8,10 Correspondence and requests for materials should be addressed to T.Yo. (Email: takashiy@agr.nagoya-u.ac.jp).

Abstract

Molecular mechanisms regulating animal seasonal breeding in response to changing photoperiod are not well understood. Rapid induction of gene expression of thyroid-hormone-activating enzyme (type 2 deiodinase, DIO2) in the mediobasal hypothalamus (MBH) of the Japanese quail (Coturnix japonica) is the earliest event yet recorded in the photoperiodic signal transduction pathway. Here we show cascades of gene expression in the quail MBH associated with the initiation of photoinduced secretion of luteinizing hormone. We identified two waves of gene expression. The first was initiated about 14 h after dawn of the first long day and included increased thyrotrophin (TSH) -subunit expression in the pars tuberalis; the second occurred approximately 4 h later and included increased expression of DIO2. Intracerebroventricular (ICV) administration of TSH to short-day quail stimulated gonadal growth and expression of DIO2 which was shown to be mediated through a TSH receptor–cyclic AMP (cAMP) signalling pathway. Increased TSH in the pars tuberalis therefore seems to trigger long-day photoinduced seasonal breeding.

1. Division of Biomodelling, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
2. Functional Genomics Subunit, Centre for Developmental Biology, RIKEN, 2-3-3 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047, Japan
3. Department of Applied Biochemistry, Faculty of Agriculture, Utsunomiya University, 350 Mine-machi, Utsunomiya, 321-8505, Japan
4. Division of Genetics and Genomics, Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Roslin, Midlothian EH25 9PS, UK
5. Laboratory of Comparative Biochemistry, Graduate School of Applied Biological Sciences, Gifu University, Gifu 501-1193, Japan
6. Department of Medical Genome Sciences, Graduate School of Frontier Sciences, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
7. Division of Biofunctions Development, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
8. Avian Bioscience Research Centre, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
9. Laboratory for Systems Biology, Centre for Developmental Biology, RIKEN, 2-3-3 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047, Japan
10. Institute for Advanced Research, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan
11. These authors contributed equally to this work.

Correspondence to: Takashi Yoshimura^1,8,10 Correspondence and requests for materials should be addressed to T.Yo. (Email: takashiy@agr.nagoya-u.ac.jp).

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