Daily expression of a clock gene in the brain and pituitary of the Malabar grouper (Epinephelus malabaricus)

The negative feedback model for gene regulation of the circadian mechanism is described for the fruitfly, Drosophila melanogaster . The conservation of function of clock molecules is illustrated by comparison with the mammalian circadian system, and the apparent swapping of roles between various canonical clock gene components is highlighted. The role of clock gene duplications and divergence of function is introduced via the timeless gene. The impressive similarities in clock gene regulation between flies and mammals could suggest that variation between more closely related species within insects might be minimal. However, this is not borne out because the expression of clock molecules in the brain of the giant silk moth, Antheraea pernyi , is not easy to reconcile with the negative feedback roles of the period and timeless genes. Variation in clock gene sequences between and within fly species is examined and the role of co-evolution between and within clock molecules is described, particularly with reference to adaptive functions of the circadian phenotype.

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Circadian influences on dopamine circuits of the brain: regulation of striatal rhythms of clock gene expression and implications for psychopathology and disease

F1000Research ◽

10.12688/f1000research.9180.1 ◽

2016 ◽

Vol 5 ◽

pp. 2062 ◽

Cited By ~ 23

Author(s):

Michael Verwey ◽

Sabine Dhir ◽

Shimon Amir

Keyword(s):

Gene Expression ◽

Circadian Rhythms ◽

Circadian Clock ◽

Clock Gene ◽

Dorsal Striatum ◽

Brain Regions ◽

Physiological Importance ◽

Clock Gene Expression ◽

Dopamine Circuits ◽

The Brain

Circadian clock proteins form an autoregulatory feedback loop that is central to the endogenous generation and transmission of daily rhythms in behavior and physiology. Increasingly, circadian rhythms in clock gene expression are being reported in diverse tissues and brain regions that lie outside of the suprachiasmatic nucleus (SCN), the master circadian clock in mammals. For many of these extra-SCN rhythms, however, the region-specific implications are still emerging. In order to gain important insights into the potential behavioral, physiological, and psychological relevance of these daily oscillations, researchers have begun to focus on describing the neurochemical, hormonal, metabolic, and epigenetic contributions to the regulation of these rhythms. This review will highlight important sites and sources of circadian control within dopaminergic and striatal circuitries of the brain and will discuss potential implications for psychopathology and disease. For example, rhythms in clock gene expression in the dorsal striatum are sensitive to changes in dopamine release, which has potential implications for Parkinson’s disease and drug addiction. Rhythms in the ventral striatum and limbic forebrain are sensitive to psychological and physical stressors, which may have implications for major depressive disorder. Collectively, a rich circadian tapestry has emerged that forces us to expand traditional views and to reconsider the psychopathological, behavioral, and physiological importance of these region-specific rhythms in brain areas that are not immediately linked with the regulation of circadian rhythms.

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Comparison of expression patterns of six canonical clock genes of follicular phase and luteal phase in Small-tailed Han sheep

Archives Animal Breeding ◽

10.5194/aab-64-457-2021 ◽

2021 ◽

Vol 64 (2) ◽

pp. 457-466

Author(s):

Qi Han ◽

Xiaoyun He ◽

Ran Di ◽

Mingxing Chu

Keyword(s):

Gene Expression ◽

Estrous Cycle ◽

Luteal Phase ◽

Clock Gene ◽

Clock Genes ◽

Expression Patterns ◽

Mrna Levels ◽

Clock Gene Expression ◽

The Relationship ◽

The Brain

Abstract. The circadian rhythm is a biological rhythm that is closely related to the rhythmic expression of a series of clock genes. Results from several studies have indicated that clock genes are associated with the estrous cycle in female animals. Until now, the relationship between estrus cycle transition and clock gene expression in reproductive-axis-related tissues has remained unknown in Small-tailed Han (STH) sheep. This study was conducted to analyze the expression patterns of six canonical clock genes (Clock, BMAL1, Per1, Per2, Cry1, and Cry2) in the follicle phase and luteal phase of STH sheep. We found that all six genes were expressed in the brain, cerebellum, hypothalamus, pituitary, ovary, uterus, and oviduct in follicle and luteal phases. The results indicated that Clock expression was significantly higher in the cerebellum, hypothalamus, and uterus of the luteal phase than that of the follicle phase, whereas BMAL1 expression was significantly higher in the hypothalamus of the luteal phase than that of the follicle phase. Per1 expression was significantly higher in the brain, cerebellum, hypothalamus, and pituitary of the luteal phase than that of the follicle phase, and Per2 expression was significantly higher in the hypothalamus, pituitary, and uterus of the luteal phase than that of the follicle phase. Cry1 expression was significantly higher in the brain, cerebellum, and hypothalamus of the luteal phase than that of the follicle phase, whereas Cry2 expression was significantly higher in the pituitary of the luteal phase than that of the follicle phase. The clock gene expression in all tissues was different between follicle and luteal phases, but all clock gene mRNA levels were found to exhibit higher expression among seven tissues in the luteal phase. Our results suggest that estrous cycles may be associated with clock gene expression in the STH sheep. This is the first study to systematically analyze the expression patterns of clock genes of different estrous cycle in ewes, which could form a basis for further studies to develop the relationship between clock genes and the estrous cycle.

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Entrainment of circadian clocks in mammals by arousal and food

Essays in Biochemistry ◽

10.1042/bse0490119 ◽

2011 ◽

Vol 49 ◽

pp. 119-136 ◽

Cited By ~ 51

Author(s):

Ralph E Mistlberger ◽

Michael C Antle

Keyword(s):

Clock Gene ◽

Gene Mutations ◽

Circadian System ◽

Neural Pathways ◽

Suprachiasmatic Nuclei ◽

Social Stimuli ◽

Clock Gene Expression ◽

Circadian Oscillators ◽

External Time ◽

The Brain

Circadian rhythms in mammals are regulated by a system of endogenous circadian oscillators (clock cells) in the brain and in most peripheral organs and tissues. One group of clock cells in the hypothalamic SCN (suprachiasmatic nuclei) functions as a pacemaker for co-ordinating the timing of oscillators elsewhere in the brain and body. This master clock can be reset and entrained by daily LD (light–dark) cycles and thereby also serves to interface internal with external time, ensuring an appropriate alignment of behavioural and physiological rhythms with the solar day. Two features of the mammalian circadian system provide flexibility in circadian programming to exploit temporal regularities of social stimuli or food availability. One feature is the sensitivity of the SCN pacemaker to behavioural arousal stimulated during the usual sleep period, which can reset its phase and modulate its response to LD stimuli. Neural pathways from the brainstem and thalamus mediate these effects by releasing neurochemicals that inhibit retinal inputs to the SCN clock or that alter clock-gene expression in SCN clock cells. A second feature is the sensitivity of circadian oscillators outside of the SCN to stimuli associated with food intake, which enables animals to uncouple rhythms of behaviour and physiology from LD cycles and align these with predictable daily mealtimes. The location of oscillators necessary for food-entrained behavioural rhythms is not yet certain. Persistence of these rhythms in mice with clock-gene mutations that disable the SCN pacemaker suggests diversity in the molecular basis of light- and food-entrainable clocks.

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Circadian rhythms in behavior and clock gene expressions in the brain of mice lacking histidine decarboxylase

Molecular Brain Research ◽

10.1016/j.molbrainres.2004.02.015 ◽

2004 ◽

Vol 124 (2) ◽

pp. 178-187 ◽

Cited By ~ 51

Author(s):

Hiroshi Abe ◽

Sato Honma ◽

Hiroshi Ohtsu ◽

Ken-ichi Honma

Keyword(s):

Circadian Rhythms ◽

Clock Gene ◽

Histidine Decarboxylase ◽

Gene Expressions ◽

The Brain

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Food-entrained circadian rhythms are sustained in arrhythmic Clk/Clk mutant mice

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00023.2003 ◽

2003 ◽

Vol 285 (1) ◽

pp. R57-R67 ◽

Cited By ~ 74

Author(s):

SiNae Pitts ◽

Elizabeth Perone ◽

Rae Silver

Keyword(s):

Circadian Rhythms ◽

Clock Gene ◽

Wheel Running ◽

Mutant Mice ◽

Circadian Oscillators ◽

Daily Food ◽

Food Anticipatory Activity ◽

Anticipatory Activity ◽

The Brain ◽

Clock Protein

Daily scheduled feeding is a potent time cue that elicits anticipatory activity in rodents. This food-anticipatory activity (FAA) is controlled by a food-entrainable oscillator (FEO) that is distinct from light-entrained oscillators of the suprachiasmatic nucleus (SCN). Circadian rhythms within the SCN depend on transcription-translation feedback loops in which CLOCK protein is a key positive regulator. The Clock gene is expressed in rhythmic tissues throughout the brain and periphery, implicating its widespread involvement in the functioning of circadian oscillators. To examine whether CLOCK protein is also necessary for the FEO, the effect of daily food restriction was studied in homozygous Clock mutant ( Clk/Clk) mice. The results show that Clk/Clk mutant mice exhibit FAA, even when their circadian wheel-running behavior is arrhythmic. As in wild-type controls, FAA in Clk/Clk mutants persists after temporal feeding cues are removed for several cycles, indicating that the FEO is a circadian timer. This is the first demonstration that the Clock gene is not necessary for the expression of a circadian, food-entrained behavior and suggests that the FEO is mediated by a molecular mechanism distinct from that of the SCN.

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