scholarly journals A circadian clock in a nonphotosynthetic prokaryote

2021 ◽  
Vol 7 (2) ◽  
pp. eabe2086
Author(s):  
Zheng Eelderink-Chen ◽  
Jasper Bosman ◽  
Francesca Sartor ◽  
Antony N. Dodd ◽  
Ákos T. Kovács ◽  
...  
Keyword(s):  
Temperature Compensation ◽  
Temporal Structure ◽  
Bacterial Biofilm ◽  
Circadian Clocks ◽  
Industrial Processes ◽  
Free Living ◽  
Considerable Potential ◽  
Free Running ◽  
Free Running Period ◽  
Constant Dark

Circadian clocks create a 24-hour temporal structure, which allows organisms to occupy a niche formed by time rather than space. They are pervasive throughout nature, yet they remain unexpectedly unexplored and uncharacterized in nonphotosynthetic bacteria. Here, we identify in Bacillus subtilis circadian rhythms sharing the canonical properties of circadian clocks: free-running period, entrainment, and temperature compensation. We show that gene expression in B. subtilis can be synchronized in 24-hour light or temperature cycles and exhibit phase-specific characteristics of entrainment. Upon release to constant dark and temperature conditions, bacterial biofilm populations have temperature-compensated free-running oscillations with a period close to 24 hours. Our work opens the field of circadian clocks in the free-living, nonphotosynthetic prokaryotes, bringing considerable potential for impact upon biomedicine, ecology, and industrial processes.

scholarly journals timrit Lengthens Circadian Period in a Temperature-Dependent Manner through Suppression of PERIOD Protein Cycling and Nuclear Localization

1999 ◽  
Vol 19 (6) ◽  
pp. 4343-4354 ◽  
Author(s):  
Akira Matsumoto ◽  
Kenji Tomioka ◽  
Yoshihiko Chiba ◽  
Teiichi Tanimura
Keyword(s):  
Nuclear Localization ◽  
Temperature Compensation ◽  
Feedback Loop ◽  
Gene Dosage ◽  
Dependent Manner ◽  
Temperature Dependent ◽  
Protein Levels ◽  
Free Running ◽  
Free Running Period ◽  
Posttranscriptional Level

ABSTRACT A fundamental feature of circadian clocks is temperature compensation of period. The free-running period of ritsu(timrit ) (a novel allele oftimeless [tim]) mutants is drastically lengthened in a temperature-dependent manner. PER and TIM protein levels become lower in timrit mutants as temperature becomes higher. This mutation reduces per mRNA but not tim mRNA abundance. PER constitutively driven by the rhodopsin1 promoter is lowered in ritmutants, indicating that timrit mainly affects the per feedback loop at a posttranscriptional level. An excess of per + gene dosage can ameliorate allrit phenotypes, including the weak nuclear localization of PER, suggesting that timrit affects circadian rhythms by reducing PER abundance and its subsequent transportation into nuclei as temperature increases.

scholarly journals Balance equations can buffer noisy and sustained environmental perturbations of circadian clocks

2010 ◽  
Vol 1 (1) ◽  
pp. 177-186 ◽  
Author(s):  
Mirela Domijan ◽  
David A. Rand
Keyword(s):  
Temperature Compensation ◽  
Regulatory Networks ◽  
Circadian Clocks ◽  
Balance Equations ◽  
New Approach ◽  
Environmental Perturbations ◽  
Environmental Fluctuations ◽  
Free Running ◽  
Temperature Levels

We present a new approach to understanding how regulatory networks such as circadian clocks might evolve robustness to environmental fluctuations. The approach is in terms of new balance equations that we derive. We use it to describe how an entrained clock can buffer the effects of daily fluctuations in light and temperature levels. We also use it to study a different approach to temperature compensation where instead of considering a free-running clock, we study temperature buffering of the phases in a light-entrained clock, which we believe is a more physiological setting.

scholarly journals Heritable circadian period length in a wild bird population

2010 ◽  
Vol 277 (1698) ◽  
pp. 3335-3342 ◽  
Author(s):  
Barbara Helm ◽  
Marcel E. Visser
Keyword(s):  
Sexual Selection ◽  
Evolutionary Ecology ◽  
Natural Populations ◽  
Parus Major ◽  
Period Length ◽  
Circadian Clocks ◽  
Short Period ◽  
High Heritability ◽  
Free Running ◽  
Free Running Period

Timing is essential, but circadian clocks, which play a crucial role in timekeeping, are almost unaddressed in evolutionary ecology. A key property of circadian clocks is their free-running period length ( τ ), i.e. the time taken for a full cycle under constant conditions. Under laboratory conditions, concordance of τ with the ambient light–dark cycle confers major fitness benefits, but little is known about period length and its implications in natural populations. We therefore studied natural variation of circadian traits in a songbird, the great tit ( Parus major ), by recording locomotor activity of 98 hand-raised, wild-derived individuals. We found, unexpectedly, that the free-running period of this diurnal species was significantly shorter than 24 h in constant dim light. We furthermore demonstrate, to our knowledge for the first time in a wild vertebrate, ample genetic variation and high heritability ( h 2 = 0.86 ± 0.24), implying that period length is potentially malleable by micro-evolutionary change. The observed, short period length may be a consequence of sexual selection, as offspring from extra-pair matings had significantly shorter free-running periods than their half-siblings from within-pair matings. These findings position circadian clocks in the ‘real world’ and underscore the value of using chronobiological approaches in evolutionary ecology. Evolutionary ecologists study variation and its fitness consequences, but often have difficulties relating behavioural variation to physiological mechanisms. The findings presented here open the possibility that properties of internal, circadian clocks affect performance in traits that are relevant to fitness and sexual selection.

Are membrane properties essential for the circadian rhythm of Gonyaulax?

1984 ◽  
Vol 247 (2) ◽  
pp. R250-R256
Author(s):  
H. G. Scholubbers ◽  
W. Taylor ◽  
L. Rensing
Keyword(s):  
Circadian Rhythm ◽  
Phase Shift ◽  
Fluorescence Polarization ◽  
The Other ◽  
Membrane Properties ◽  
Response Curves ◽  
Whole Cells ◽  
Different Temperatures ◽  
Free Running ◽  
Free Running Period

Membrane properties of whole cells of Gonyaulax polyedra were measured by fluorescence polarization. Circadian changes of fluorescence polarization exist in exponentially growing cultures. They show an amplitude larger than that of stationary cultures, indicating that a part of the change is due to or amplified by an ongoing cell cycle. Measurements of parameters of the circadian glow rhythm were analyzed for possible correlation with the membrane data. Considerable differences (Q10 = 2.5-3.0) in fluorescence polarization were found in cultures kept at different temperatures ranging from 15 to 27.5 degrees C. The free-running period length at different temperatures, on the other hand, differed only slightly (Q10 = 0.9-1.1). Stationary cultures showed higher fluorescence polarization compared with growing cultures, whereas the free-running period lengths did not differ in cultures of various densities and growth rates. Temperature steps of different sign changed the fluorescence polarization slightly in different directions. The phase shift of 4-h pulses (-5, -9, +7 degrees C) resulted in maximal phase advances of 4, 6, and 2 h, respectively. The phasing of the phase-response curves was identical in all these experiments, a finding not to be expected if the pulses act via the measured membrane properties. Pulses of drugs that change the fluorescence polarization (e.g., chlorpromazine and lidocaine) did not or only slightly phase-shift the circadian rhythm.

Gonadal hormones organize and modulate the circadian system of the rat

1981 ◽  
Vol 241 (1) ◽  
pp. R62-R66 ◽  
Author(s):  
H. E. Albers
Keyword(s):  
Testosterone Propionate ◽  
Wheel Running ◽  
Activity Rhythm ◽  
Gonadal Hormones ◽  
Circadian System ◽  
Female Rats ◽  
Constant Darkness ◽  
Before And After ◽  
Free Running ◽  
Free Running Period

The circadian wheel-running rhythms of gonadectomized adult male, female, and perinatally androgenized female rats, maintained in constant darkness, were examined before and after implantation of Silastic capsules containing cholesterol (C) or estradiol-17 beta (E). The free-running period of the activity rhythm (tau) before capsule implantation tended to be shorter in animals exposed to perinatal androgen. Administration of C did not reliably alter tau in any group. E significantly shortened tau in 100% of females injected with oil on day 3 of life. In females, injected with 3.5 micrograms testosterone propionate on day 3, and males, E shortened or lengthened tau, with the direction and magnitude of this change in tau inversely related to the length of the individual's pretreatment tau. These data indicate that the presence of perinatal androgen does not eliminate the sensitivity of the circadian system of the rat to estrogen, since estrogen alters tau in a manner that depends on its pretreatment length.

scholarly journals Genetic interactions between clock mutations in Neurospora crassa : can they help us to understand complexity?

2001 ◽  
Vol 356 (1415) ◽  
pp. 1717-1724 ◽  
Author(s):  
Louis W. Morgan ◽  
Jerry F. Feldman ◽  
Deborah Bell-Pedersen
Keyword(s):  
Coupled Oscillators ◽  
Temperature Compensation ◽  
White Collar ◽  
Circadian System ◽  
Genetic Interactions ◽  
Circadian Clocks ◽  
Metabolic Effects ◽  
Clock Model ◽  
Number Of Genes ◽  
Single Oscillator

Recent work on circadian clocks in Neurospora has primarily focused on the frequency ( frq ) and white–collar ( wc ) loci. However, a number of other genes are known that affect either the period or temperature compensation of the rhythm. These include the period (no relationship to the period gene of Drosophila ) genes and a number of genes that affect cellular metabolism. How these other loci fit into the circadian system is not known, and metabolic effects on the clock are typically not considered in single–oscillator models. Recent evidence has pointed to multiple oscillators in Neurospora , at least one of which is predicted to incorporate metabolic processes. Here, the Neurospora clock–affecting mutations will be reviewed and their genetic interactions discussed in the context of a more complex clock model involving two coupled oscillators: a FRQ/WC–based oscillator and a ‘ frq –less’ oscillator that may involve metabolic components.

Effects of aging on entrainment and rate of resynchronization of circadian locomotor activity

1992 ◽  
Vol 263 (5) ◽  
pp. R1099-R1103 ◽  
Author(s):  
P. C. Zee ◽  
R. S. Rosenberg ◽  
F. W. Turek
Keyword(s):  
Circadian Rhythm ◽  
Locomotor Activity ◽  
Activity Rhythm ◽  
Phase Advance ◽  
Middle Aged ◽  
Age Related ◽  
Free Running ◽  
Effects Of Aging ◽  
Free Running Period ◽  
Related Phase

The phase angle of entrainment of the circadian rhythm of the locomotor activity rhythm to a light-dark (LD) cycle was examined in young (2-5 mo old) and middle-aged (13-16 mo old) hamsters. An age-related phase advance in the onset of locomotor activity relative to lights off was seen during stable entrainment to a 14:10-h LD cycle. In addition, the effects of age on the rate of reentrainment of the circadian rhythm of locomotor activity were examined by subjecting young and middle-aged hamsters to either an 8-h advance or delay shift of the LD cycle. Middle-aged hamsters resynchronized more rapidly after a phase advance of the LD cycle than did young hamsters, whereas young hamsters were able to phase delay more rapidly than middle-aged hamsters. The age-related phase advance of activity onset under entrained conditions, and the alteration of responses in middle-aged hamsters reentraining to a phase-shifted LD cycle, may be due to the shortening of the free-running period of the circadian rhythm of locomotor activity with advancing age that has previously been observed in this species.

scholarly journals A circadian clock in Saccharomyces cerevisiae

2010 ◽  
Vol 107 (5) ◽  
pp. 2043-2047 ◽  
Author(s):  
Zheng Eelderink-Chen ◽  
Gabriella Mazzotta ◽  
Marcel Sturre ◽  
Jasper Bosman ◽  
Till Roenneberg ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Genetic Model ◽  
Circadian Clocks ◽  
Model Systems ◽  
Model Organisms ◽  
Biological Clocks ◽  
Experimental Systems ◽  
Fundamental Biological Process ◽  
Free Running ◽  
And Behavior

Circadian timing is a fundamental biological process, underlying cellular physiology in animals, plants, fungi, and cyanobacteria. Circadian clocks organize gene expression, metabolism, and behavior such that they occur at specific times of day. The biological clocks that orchestrate these daily changes confer a survival advantage and dominate daily behavior, for example, waking us in the morning and helping us to sleep at night. The molecular mechanism of circadian clocks has been sketched out in genetic model systems from prokaryotes to humans, revealing a combination of transcriptional and posttranscriptional pathways, but the clock mechanism is far from solved. Although Saccharomyces cerevisiae is among the most powerful genetic experimental systems and, as such, could greatly contribute to our understanding of cellular timing, it still remains absent from the repertoire of circadian model organisms. Here, we use continuous cultures of yeast, establishing conditions that reveal characteristic clock properties similar to those described in other species. Our results show that metabolism in yeast shows systematic circadian entrainment, responding to cycle length and zeitgeber (stimulus) strength, and a (heavily damped) free running rhythm. Furthermore, the clock is obvious in a standard, haploid, auxotrophic strain, opening the door for rapid progress into cellular clock mechanisms.

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