TY - JOUR
T1 - Functional development of the zebrafish pineal gland
T2 - Light-induced expression of period2 is required for onset of the circadian clock
AU - Ziv, L.
AU - Levkovitz, S.
AU - Toyama, R.
AU - Falcon, J.
AU - Gothilf, Yoav
PY - 2005/5
Y1 - 2005/5
N2 - In zebrafish, the pineal gland is a photoreceptive organ that contains an intrinsic circadian oscillator and exhibits rhythmic arylalkylamine-N-acetyltransferase (zfaanat2) mRNA expression. In the present study, we investigated the role of light and of a clock gene, zperiod2 (zper2), in the development of this rhythm. Analysis of zfaanat2 mRNA expression in the pineal gland of 3-day-old zebrafish embryos after exposure to different photoperiodic regimes indicated that light is required for proper development of the circadian clock-controlled rhythmic expression of zfaanat2, and that a 1-h light pulse is sufficient to initiate this rhythm. Analysis of zper2 mRNA expression in zebrafish embryos exposed to different photoperiodic regimes indicated that zper2 expression is transiently up-regulated by light but is not regulated by the circadian oscillator. To establish the association between light-induced zper2 expression and light-induced clock-controlled zfaanat2 rhythm, zPer2 knock-down experiments were performed. The zfaanat2 mRNA rhythm, induced by a 1-h light pulse, was abolished in zPer2 knock-down embryos. These experiments indicated that light-induced zper2 expression is crucial for establishment of the clock-controlled zfaanat2 rhythm in the zebrafish pineal gland.
AB - In zebrafish, the pineal gland is a photoreceptive organ that contains an intrinsic circadian oscillator and exhibits rhythmic arylalkylamine-N-acetyltransferase (zfaanat2) mRNA expression. In the present study, we investigated the role of light and of a clock gene, zperiod2 (zper2), in the development of this rhythm. Analysis of zfaanat2 mRNA expression in the pineal gland of 3-day-old zebrafish embryos after exposure to different photoperiodic regimes indicated that light is required for proper development of the circadian clock-controlled rhythmic expression of zfaanat2, and that a 1-h light pulse is sufficient to initiate this rhythm. Analysis of zper2 mRNA expression in zebrafish embryos exposed to different photoperiodic regimes indicated that zper2 expression is transiently up-regulated by light but is not regulated by the circadian oscillator. To establish the association between light-induced zper2 expression and light-induced clock-controlled zfaanat2 rhythm, zPer2 knock-down experiments were performed. The zfaanat2 mRNA rhythm, induced by a 1-h light pulse, was abolished in zPer2 knock-down embryos. These experiments indicated that light-induced zper2 expression is crucial for establishment of the clock-controlled zfaanat2 rhythm in the zebrafish pineal gland.
KW - Arylalkylamine-N-acetyltransferase
KW - In situ hybridization
KW - Melatonin
KW - Photoreceptor
UR - http://www.scopus.com/inward/record.url?scp=19044392845&partnerID=8YFLogxK
U2 - 10.1111/j.1365-2826.2005.01315.x
DO - 10.1111/j.1365-2826.2005.01315.x
M3 - ???researchoutput.researchoutputtypes.contributiontojournal.article???
AN - SCOPUS:19044392845
SN - 0953-8194
VL - 17
SP - 314
EP - 320
JO - Journal of Neuroendocrinology
JF - Journal of Neuroendocrinology
IS - 5
ER -