Circadian gene expression patterns of melanopsin and pinopsin in the chick pineal gland.
The directly light-sensitive chick pineal gland contains at least two photopigments. Pinopsin seems to mediate the acute inhibitory effect of light on melatonin synthesis, whereas melanopsin may act by phase-shifting the intrapineal circadian clock. In the present study we have investigated, by means of quantitative RT-PCR, the daily rhythm of photopigment gene expression as monitored by mRNA levels. Under a 12-h light/12-h dark cycle, the mRNA levels of both pigments were 5-fold higher in the transitional phase from light to dark than at night, both in vivo and in vitro. Under constant darkness in vivo and in vitro, the peak of pinopsin mRNA levels was attenuated, whereas that of melanopsin was not. Thus, whereas the daily rhythm of pinopsin gene expression is dually regulated by light plus the intrapineal circadian oscillator, that of melanopsin appears to depend solely on the oscillator.
Holthues
Heike
H
Department of Anatomy, Johannes Gutenberg University, 55099 Mainz, Germany. holthues@uni-mainz.de
Engel
Lydia
L
Spessert
Rainer
R
Vollrath
Lutz
L
D000221:Adaptation, Ocular / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D030161:Avian Proteins; D002478:Cells, Cultured; D002645:Chickens; D002940:Circadian Rhythm / Q000502:physiology* / Q000528:radiation effects; D005786:Gene Expression Regulation / Q000502:physiology* / Q000528:radiation effects*; D008027:Light; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D017440:Photoperiod; D010870:Pineal Gland / Q000378:metabolism* / Q000528:radiation effects*; D017299:Rod Opsins / Q000378:metabolism*; D000099210:Melanopsin
D030161:Avian Proteins; D009419:Nerve Tissue Proteins; D017299:Rod Opsins; D000099210:Melanopsin; C090139:OPNP protein, chicken