Effects of the TAU Mutation on Circadian Organization

Chronobiology is the scientific discipline which considers biological phenomena in relation to time, which assumes itself biological identity. Many physiological processes are cyclically regulated by intrinsic clocks and many pathological events show a circadian time-related occurrence. Even the pituitary–thyroid axis is under the control of a central clock, and the hormones of the pituitary–thyroid axis exhibit circadian, ultradian and circannual rhythmicity. This review, after describing briefly the essential principles of chronobiology, will be focused on the results of personal experiences and of other studies on this issue, paying particular attention to those regarding the thyroid implications, appearing in the literature as reviews, metanalyses, original and observational studies until 28 February 2021 and acquired from two databases (Scopus and PubMed). The first input to biological rhythms is given by a central clock located in the suprachiasmatic nucleus (SCN), which dictates the timing from its hypothalamic site to satellite clocks that contribute in a hierarchical way to regulate the physiological rhythmicity. Disruption of the rhythmic organization can favor the onset of important disorders, including thyroid diseases. Several studies on the interrelationship between thyroid function and circadian rhythmicity demonstrated that thyroid dysfunctions may affect negatively circadian organization, disrupting TSH rhythm. Conversely, alterations of clock machinery may cause important perturbations at the cellular level, which may favor thyroid dysfunctions and also cancer.

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Circadian organization of locomotor activity in the Turkish hamster (Mesocricetus brandti)

Behavioral and Neural Biology ◽

10.1016/s0163-1047(83)91520-0 ◽

1983 ◽

Vol 37 (2) ◽

pp. 362-366 ◽

Cited By ~ 4

Author(s):

H. Elliott Albers ◽

Dennis S. Carter ◽

Janet M. Darrow ◽

Bruce D. Goldman

Keyword(s):

Locomotor Activity ◽

Circadian Organization ◽

Turkish Hamster

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Multiphotoreceptor and multioscillator system in avian circadian organization

Microscopy Research and Technique ◽

10.1002/jemt.1067 ◽

2001 ◽

Vol 53 (1) ◽

pp. 43-47 ◽

Cited By ~ 15

Author(s):

Tadashi Oishi ◽

Mikaru Yamao ◽

Chieko Kondo ◽

Yuka Haida ◽

Atsuko Masuda ◽

...

Keyword(s):

Circadian Organization

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Circadian organization of chitin in some insect skeletons

Journal of Cell Science ◽

10.1242/jcs.s3-106.76.315 ◽

1965 ◽

Vol s3-106 (76) ◽

pp. 315-325

Author(s):

A. C. NEVILLE

Keyword(s):

Circadian Clock ◽

General Feature ◽

Periplaneta Americana ◽

Constant Darkness ◽

Actual Rate ◽

Rate Of Increase ◽

Parallel Fibres ◽

Astronomical Clock ◽

Circadian Organization ◽

Water Bugs

A circadian clock is shown to be involved in the control of macromolecular orientation of chitin by cells secreting and organizing insect endocuticle. Daily organization of locust endocuticle into alternating lamellate and non-lamellate layers persists in constant temperature (36° C) and constant darkness for at least 2 weeks; the freerunning period is then about 23 h, so that after a number of days the circadian clock is 180° out of phase with the astronomical clock, with which it is normally phased. The rhythm is almost independent of temperature, with a Q10 of 1.04, as contrasted with a Q10 of 2.0 for the actual rate of increase of endocuticular thickness. Locust epidermal cells differ in response to specific imposed environmental conditions according to their location in the integument. In some cells, constant low temperature uncouples chitin lamellogenesis from the circadian clock, provided that illumination (light or dark) is constant also: the result is continuously lamellate endocuticle. In other cells constant light acts as an uncoupling factor, provided that temperature (high or low) is constant also: the result in this case is continuously non-lamellate endocuticle. The circadian rhythm of chitin lamellogenesis persists in a cave cricket (Dolichopoda linderi). A similar circadian lamellogenesis rhythm occurs in the endocuticle of nymphs and adults of the cockroach Periplaneta americana. A crossed-fibre multiple-ply endocuticle in the legs and wings of giant toe-biter water bugs (Belosto-matidae) also displays circadian organization, the chitin macromolecules in any one layer lying in parallel fibres, at an angle of approximately 6o° to those in the next layer. It is suggested that daily organization of the skeleton may be a general feature of arthropods. Examples include the phenomena of timing of chitin lamellogenesis; chitin crossed-fibrillar organization; degree of fluorescence of the rubber-like protein resilin; and mineralization of crayfish gastroliths.

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Relationship between circadian period and body size in the tau-mutant golden hamster

Canadian Journal of Physiology and Pharmacology ◽

10.1139/cjpp-2013-0276 ◽

2014 ◽

Vol 92 (1) ◽

pp. 27-33

Author(s):

Roberto Refinetti

Keyword(s):

Body Size ◽

Single Gene ◽

Pleiotropic Effect ◽

Circadian Period ◽

Golden Syrian Hamster ◽

Casein Kinase 1 ◽

Reduced Body ◽

Short Period ◽

Casein Kinase 1 Epsilon ◽

Tau Mutation

The tau mutation in the golden (Syrian) hamster is a single gene mutation that drastically affects the speed of the circadian clock, in such a way that homozygous mutants have an endogenous circadian period of 20 h (compared with 24 h for wild-type hamsters). While studying the circadian system of tau-mutant hamsters during the past 25 years, several authors have noted an apparent relationship between circadian period and body size in these animals. This study, based on 181 hamsters from 24 litters, confirmed previous observations that a shorter circadian period is associated with smaller body size, documented a sex difference in this association, and evaluated several mechanisms that might explain the phenomenon (such as different organ sizes, body composition, and metabolic rate). The obtained evidence suggests that the reduced body size of short-period hamsters is likely a pleiotropic effect of the tau allele (an allele of the casein kinase 1 epsilon gene) rather than a consequence of the shortened circadian period.

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