Temporal expression of seven clock genes in the suprachiasmatic nucleus and the pars tuberalis of the sheep: Evidence for an internal coincidence timer

G. Lincoln, S. Messager, H. Andersson, David Grey Hazlerigg

Research output: Contribution to journalArticle

169 Citations (Scopus)

Abstract

The 24-h expression of seven clock genes (Bmal1, Clock, Pert, Pert, Cry1, Cry2, and CK1epsilon) was assayed by in situ hybridization in the suprachiasmatic nucleus (SCN) and the pars tuberalis (PT) of the pituitary gland, collected every 4 h throughout 24 h, from female Soay sheep kept under long (16-h light/8-h dark) or short (8-h light/16-h dark) photoperiods. Locomotor activity was diurnal, inversely related to melatonin secretion, and prolactin levels were increased under long days. All clock genes were expressed in the ovine SCN and PT. In the SCN, there was a 24-h rhythm in Clock expression, in parallel with Bmal1, in antiphase with cycles in Per1 and Pert; there was low-amplitude oscillation of Cry1 and Cry2. The waveform of only Pert and Pert expression was affected by photoperiod, with extended elevated expression under long days. In the PT, the high-amplitude 24-h cycles in the expression of Bmal1, Clock, Per1, Pert, Cry1, and Cry2, but not CK1epsilon, were influenced by photoperiod. Perl and Pert peaked during the day, whereas Cry1 and Cry2 peaked early in the night. Hence, photoperiod via melatonin had a marked effect on the phase relationship between Per/Cry genes in the PT. This supports the conclusion that an "external coincidence model" best explains the way photoperiod affects the waveform of clock gene expression in the SCN, the central pacemaker, whereas an "internal coincidence model" best explains the way melatonin affects the phasing of clock gene expression in the PT to mediate the photoperiodic control of a summer or winter physiology.

Original languageEnglish
Pages (from-to)13890-13895
Number of pages5
JournalPNAS
Volume99
Issue number21
DOIs
Publication statusPublished - Oct 2002

Keywords

  • DECODING PHOTOPERIODIC TIME
  • CIRCADIAN EXPRESSION
  • MELATONIN RECEPTORS
  • SIBERIAN HAMSTER
  • PERIOD GENE
  • PER1
  • SENSITIZATION
  • LOCALIZATION
  • PITUITARY
  • RPER2

Cite this

Temporal expression of seven clock genes in the suprachiasmatic nucleus and the pars tuberalis of the sheep: Evidence for an internal coincidence timer. / Lincoln, G.; Messager, S.; Andersson, H.; Hazlerigg, David Grey.

In: PNAS, Vol. 99, No. 21, 10.2002, p. 13890-13895.

Research output: Contribution to journalArticle

Lincoln, G. ; Messager, S. ; Andersson, H. ; Hazlerigg, David Grey. / Temporal expression of seven clock genes in the suprachiasmatic nucleus and the pars tuberalis of the sheep: Evidence for an internal coincidence timer. In: PNAS. 2002 ; Vol. 99, No. 21. pp. 13890-13895.
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AU - Messager, S.

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AU - Hazlerigg, David Grey

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N2 - The 24-h expression of seven clock genes (Bmal1, Clock, Pert, Pert, Cry1, Cry2, and CK1epsilon) was assayed by in situ hybridization in the suprachiasmatic nucleus (SCN) and the pars tuberalis (PT) of the pituitary gland, collected every 4 h throughout 24 h, from female Soay sheep kept under long (16-h light/8-h dark) or short (8-h light/16-h dark) photoperiods. Locomotor activity was diurnal, inversely related to melatonin secretion, and prolactin levels were increased under long days. All clock genes were expressed in the ovine SCN and PT. In the SCN, there was a 24-h rhythm in Clock expression, in parallel with Bmal1, in antiphase with cycles in Per1 and Pert; there was low-amplitude oscillation of Cry1 and Cry2. The waveform of only Pert and Pert expression was affected by photoperiod, with extended elevated expression under long days. In the PT, the high-amplitude 24-h cycles in the expression of Bmal1, Clock, Per1, Pert, Cry1, and Cry2, but not CK1epsilon, were influenced by photoperiod. Perl and Pert peaked during the day, whereas Cry1 and Cry2 peaked early in the night. Hence, photoperiod via melatonin had a marked effect on the phase relationship between Per/Cry genes in the PT. This supports the conclusion that an "external coincidence model" best explains the way photoperiod affects the waveform of clock gene expression in the SCN, the central pacemaker, whereas an "internal coincidence model" best explains the way melatonin affects the phasing of clock gene expression in the PT to mediate the photoperiodic control of a summer or winter physiology.

AB - The 24-h expression of seven clock genes (Bmal1, Clock, Pert, Pert, Cry1, Cry2, and CK1epsilon) was assayed by in situ hybridization in the suprachiasmatic nucleus (SCN) and the pars tuberalis (PT) of the pituitary gland, collected every 4 h throughout 24 h, from female Soay sheep kept under long (16-h light/8-h dark) or short (8-h light/16-h dark) photoperiods. Locomotor activity was diurnal, inversely related to melatonin secretion, and prolactin levels were increased under long days. All clock genes were expressed in the ovine SCN and PT. In the SCN, there was a 24-h rhythm in Clock expression, in parallel with Bmal1, in antiphase with cycles in Per1 and Pert; there was low-amplitude oscillation of Cry1 and Cry2. The waveform of only Pert and Pert expression was affected by photoperiod, with extended elevated expression under long days. In the PT, the high-amplitude 24-h cycles in the expression of Bmal1, Clock, Per1, Pert, Cry1, and Cry2, but not CK1epsilon, were influenced by photoperiod. Perl and Pert peaked during the day, whereas Cry1 and Cry2 peaked early in the night. Hence, photoperiod via melatonin had a marked effect on the phase relationship between Per/Cry genes in the PT. This supports the conclusion that an "external coincidence model" best explains the way photoperiod affects the waveform of clock gene expression in the SCN, the central pacemaker, whereas an "internal coincidence model" best explains the way melatonin affects the phasing of clock gene expression in the PT to mediate the photoperiodic control of a summer or winter physiology.

KW - DECODING PHOTOPERIODIC TIME

KW - CIRCADIAN EXPRESSION

KW - MELATONIN RECEPTORS

KW - SIBERIAN HAMSTER

KW - PERIOD GENE

KW - PER1

KW - SENSITIZATION

KW - LOCALIZATION

KW - PITUITARY

KW - RPER2

U2 - 10.1073/pnas.212517599

DO - 10.1073/pnas.212517599

M3 - Article

VL - 99

SP - 13890

EP - 13895

JO - PNAS

JF - PNAS

SN - 0027-8424

IS - 21

ER -