Temporal-spatial characterization of chicken clock genes: circadian expression in retina, pineal gland, and peripheral tissues.
The molecular core of the vertebrate circadian clock is a set of clock genes, whose products interact to control circadian changes in physiology. These clock genes are expressed in all tissues known to possess an endogenous self-sustaining clock, and many are also found in peripheral tissues. In the present study, the expression patterns of two clock genes, cBmal1 and cMOP4, were examined in the chicken, a useful model for analysis of the avian circadian system. In two tissues which contain endogenous clocks--the pineal gland and retina--circadian fluctuations of both cBmal1 and cMOP4 mRNAs were observed to be synchronous; highest levels occurred at Zeitgeber time 12. Expression of these genes is also rhythmic in several peripheral tissues; however, the phases of these rhythms differ from those in the pineal gland and retina: in the liver the peaks of cMOP4 and cBmal1 mRNAs are delayed 4-8 h and in the heart they are advanced by 4 h, relative to those in the pineal gland and retina. These results provide the first temporal characterization of cBmal1 and cMOP4 mRNAs in avian tissues: their presence in avian peripheral tissues indicates they may influence temporal features of daily rhythms in biochemical, physiological, and behavioral functions at these sites.
Chong
Nelson W
NW
Division of Cardiology, Department of Medicine, Glenfield General Hospital, Clinical Sciences Wing, University of Leicester, Leicester LE3 9QP, UK. nc69@le.ac.uk
Chaurasia
Shyam S
SS
Haque
Rashidul
R
Klein
David C
DC
Iuvone
P Michael
PM
D056930:ARNTL Transcription Factors; D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D001683:Biological Clocks / Q000502:physiology; D015152:Blotting, Northern; D002645:Chickens; D002940:Circadian Rhythm / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology*; D008297:Male; D008969:Molecular Sequence Data; D009928:Organ Specificity; D017440:Photoperiod; D010870:Pineal Gland / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D012160:Retina / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000235:genetics*
D056930:ARNTL Transcription Factors; D051792:Basic Helix-Loop-Helix Proteins; D012333:RNA, Messenger; D014157:Transcription Factors