The Sense of time: Evidence for its Molecular Basis in the Eukaryotic Gene-Action System

Ehret, Charles F.

doi:10.1016/b978-0-12-005215-8.50009-7

Cited by 48 publications

(17 citation statements)

References 47 publications

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“…Humans show consistent and repeatable between-individual differences in their average level of circadian behaviours, such as awakening time, rest onset or rest duration, defining different chronotypes [1,2]. Chronotypes reflect the behavioural manifestation of an individual's underlying molecular clock, have fundamental implications for wellbeing and health and have been frequently linked to fitness ([3] and see review by Adan et al .…”

Section: Introductionmentioning

confidence: 99%

Repeatability of circadian behavioural variation revealed in free-ranging marine fish

Alós¹,

Martorell-Barceló²,

Campos-Candela³

2017

R. Soc. open sci.

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Repeatable between-individual differences in the behavioural manifestation of underlying circadian rhythms determine chronotypes in humans and terrestrial animals. Here, we have repeatedly measured three circadian behaviours, awakening time, rest onset and rest duration, in the free-ranging pearly razorfish, Xyrithchys novacula, facilitated by acoustic tracking technology and hidden Markov models. In addition, daily travelled distance, a standard measure of daily activity as fish personality trait, was repeatedly assessed using a State-Space Model. We have decomposed the variance of these four behavioural traits using linear mixed models and estimated repeatability scores (R) while controlling for environmental co-variates: year of experimentation, spatial location of the activity, fish size and gender and their interactions. Between- and within-individual variance decomposition revealed significant Rs in all traits suggesting high predictability of individual circadian behavioural variation and the existence of chronotypes. The decomposition of the correlations among chronotypes and the personality trait studied here into between- and within-individual correlations did not reveal any significant correlation at between-individual level. We therefore propose circadian behavioural variation as an independent axis of the fish personality, and the study of chronotypes and their consequences as a novel dimension in understanding within-species fish behavioural diversity.

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Section: Introductionmentioning

confidence: 99%

Repeatability of circadian behavioural variation revealed in free-ranging marine fish

Alós¹,

Martorell-Barceló²,

Campos-Candela³

2017

R. Soc. open sci.

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“…Originally, the term chronotype had covered this broad range of processes. It was described by Charles Ehret [144] as the 'temporal phenotype' of an organism, a 24-h map of the phases of the peaks of various rhythms. Obviously, some of these rhythms are independent of one another, while others are not.…”

Section: (B) Chronotypementioning

confidence: 99%

Two sides of a coin: ecological and chronobiological perspectives of timing in the wild

Helm

Visser

Schwartz

et al. 2017

Phil. Trans. R. Soc. B

132

199

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Most processes within organisms, and most interactions between organisms and their environment, have distinct time profiles. The temporal coordination of such processes is crucial across levels of biological organization, but disciplines differ widely in their approaches to study timing. Such differences are accentuated between ecologists, who are centrally concerned with a holistic view of an organism in relation to its external environment, and chronobiologists, who emphasize internal timekeeping within an organism and the mechanisms of its adjustment to the environment. We argue that ecological and chronobiological perspectives are complementary, and that studies at the intersection will enable both fields to jointly overcome obstacles that currently hinder progress. However, to achieve this integration, we first have to cross some conceptual barriers, clarifying prohibitively inaccessible terminologies. We critically assess main assumptions and concepts in either field, as well as their common interests. Both approaches intersect in their need to understand the extent and regulation of temporal plasticity, and in the concept of 'chronotype', i.e. the characteristic temporal properties of individuals which are the targets of natural and sexual selection. We then highlight promising developments, point out open questions, acknowledge difficulties and propose directions for further integration of ecological and chronobiological perspectives through Wild Clock research.

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“…INTRODUCTION Zeitgebers give us time, but do not force it on ushumans come in different chronotypes (a term coined by Ehret, 1974) that behave differently with respect to external zeitgebers, be they watches, sunrises, or social cues.…”

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confidence: 99%

Chronotypes and rhythm stability in mice

Wicht

Korf

Ackermann

et al. 2013

Chronobiology International

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Humans come in different chronotypes: The phase of their sleep-wake cycle with respect to the phase of the external, sidereal cycle of night and day differs. Colloquially, the early chronotypes are addressed as "larks," the late ones as "owls." The human chronotype can be quantified in hours and minutes of local time by determining the median of the sleep phase. Demographically, early and late human chronotypes differ with respect to the stability of their rhythms and the prevalence of several widespread diseases and risk factors, such as depression, nicotine abuse, and others. Inbred mice are widely used in chronobiological research as model organisms, but up to now there was no way to chronotype them. We have developed a method to chronotype mice in hours and fractions of hours by measuring the median of activity (MoA) and have shown that different mouse strains have significantly different MoAs and, thus, chronotypes. We have further developed methods to estimate the stability of the behavioral rhythms and found that "late" mice have relatively instable rhythms. Our methods permit the use of inbred mice for investigations into the molecular and genetic background of the chronotype and the prevalence of risks and diseases that are associated with it.

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The Sense of time: Evidence for its Molecular Basis in the Eukaryotic Gene-Action System

Cited by 48 publications

References 47 publications

Repeatability of circadian behavioural variation revealed in free-ranging marine fish

Repeatability of circadian behavioural variation revealed in free-ranging marine fish

Two sides of a coin: ecological and chronobiological perspectives of timing in the wild

Chronotypes and rhythm stability in mice

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