We compared the period of the rhythm of plasma melatonin, driven by the hypothalamic circadian pacemaker, to in vitro periodicity in cultured peripheral fibroblasts to assess the effects on these rhythms of a polymorphism of PER3 (rs57875989), which is associated with sleep timing. In vitro circadian period was determined using luminometry of cultured fibroblasts, in which the expression of firefly luciferase was driven by the promoter of the circadian gene Arntl (Bmal1). The period of the melatonin rhythm was assessed in a 9-d forced desynchrony protocol, minimizing confounding effects of sleep-wake and light-dark cycles on circadian rhythmicity. In vitro periods (32 participants, 24.61±0.33 h, mean±sd) were longer than in vivo periods (31 participants, 24.16±0.17 h; P0.4). Analyses of replicate in vitro assessments demonstrated that circadian period was reproducible within individuals (intraclass correlation=0.62), but in vivo and in vitro period assessments did not correlate (P>0.9). In accordance with circadian entrainment theory, in vivo period correlated with the timing of melatonin (P
von Schantz M, Taporoski TP, Horimoto AR, Duarte NE, Vallada H, Krieger JE, Pedrazzoli M, Negrão AB, Pereira AC (2015) Distribution and heritability of diurnal preference (chronotype) in a rural Brazilian family-based cohort, the Baependi study., Scientific Reports 5 9214 Nature Publishing Group
Diurnal preference (chronotype) is a useful instrument for studying circadian biology in humans. It harbours trait-like dimensions relating to circadian period and sleep homeostasis, but also has ontogenetic components (morningness increases with age). We used the Morningness-Eveningness questionnaire (MEQ) in the Baependi study, a family-based cohort study based in a small town in Minas Gerais, Brazil. The population is highly admixed and has a cohesive and conservative lifestyle. 825 individuals (497 female) aged 18-89 years (average ± SD = 46.4 ± 16.3) and belonging to 112 different families participated in this study. The average MEQ score was 63.5 ± 11.2 with a significant (P
Egan KJ, von Schantz M, Negrão AB, Santos HC, Horimoto ARVR, Duarte NE, Gonçalves GC, Soler JMP, de Andrade M, Lorenzi-Filho G, Vallada H, Taporoski TP, Pedrazzoli M, Azambuja AP, de Oliveira CM, Alvim RO, Krieger JE, Pereira AC (2016) Cohort profile: the Baependi Heart Study--a family-based, highly admixed cohort study in a rural Brazilian town, BMJ Open 6 (10) e011598
BMJ Publishing Group
Purpose Cardiovascular disease (CVD) is a major challenge to global health. The same epidemiological transition scenario is replayed as countries develop, but with variations based on environment, culture and ethnic mixture. The Baependi Heart Study was set up in 2005 to develop a longitudinal family-based cohort study that reflects on some of the genetic and lifestyle-related peculiarities of the Brazilian populations, in order to evaluate genetic and environmental influences on CVD risk factor traits.
Participants Probands were recruited in Baependi, a small rural town in the state of Minas Gerais, Brazil, following by first-degree and then increasingly more distant relatives. The first follow-up wave took place in 2010, and the second in 2016. At baseline, the study evaluated 1691 individuals across 95 families. Cross-sectional data have been collected for 2239 participants.
Findings to date Environmental and lifestyle factors and measures relevant to cardiovascular health have been reported. Having expanded beyond cardiovascular health outcomes, the phenotype datasets now include genetics, biochemistry, anthropometry, mental health, sleep and circadian rhythms. Many of these have yielded heritability estimates, and a shared genetic background of anxiety and depression has recently been published. In spite of universal access to electricity, the population has been found to be strongly shifted towards morningness compared with metropolitan areas.
Future plans A new follow-up, marking 10?years of the study, is ongoing in 2016, in which data are collected as in 2010 (with the exception of the neuropsychiatric protocol). In addition to this, a novel questionnaire package collecting information about intelligence, personality and spirituality is being planned. The data set on circadian rhythms and sleep will be amended through additional questionnaires, actimetry, home sleep EEG recording and dim light melatonin onset (DLMO) analysis. Finally, the anthropometric measures will be expanded by adding three-dimensional facial photography, voice recording and anatomical brain MRI.
Lazar AS, Santhi N, Hasan S, Lo JC, Johnston JD, Von Schantz M, Archer SN, Dijk DJ (2012) Circadian period and the timing of melatonin onset in men and women: predictors of sleep during the weekend and in the laboratory., J Sleep Res
Sleep complaints and irregular sleep patterns, such as curtailed sleep during workdays and longer and later sleep during weekends, are common. It is often implied that differences in circadian period and in entrained phase contribute to these patterns, but few data are available. We assessed parameters of the circadian rhythm of melatonin at baseline and in a forced desynchrony protocol in 35 participants (18 women) with no sleep disorders. Circadian period varied between 23 h 50 min and 24 h 31 min, and correlated positively (n = 31, r(s) = 0.43, P = 0.017) with the timing of the melatonin rhythm relative to habitual bedtime. The phase of the melatonin rhythm correlated with the Insomnia Severity Index (n = 35, r(s) = 0.47, P = 0.004). Self-reported time in bed during free days also correlated with the timing of the melatonin rhythm (n = 35, r(s) = 0.43, P = 0.01) as well as with the circadian period (n = 31, r(s) = 0.47, P = 0.007), such that individuals with a more delayed melatonin rhythm or a longer circadian period reported longer sleep during the weekend. The increase in time in bed during the free days correlated positively with circadian period (n = 31, r(s) = 0.54, P = 0.002). Polysomnographically assessed latency to persistent sleep (n = 34, r(s) = 0.48, P = 0.004) correlated with the timing of the melatonin rhythm when participants were sleeping at their habitual bedtimes in the laboratory. This correlation was significantly stronger in women than in men (Z = 2.38, P = 0.017). The findings show that individual differences in circadian period and phase of the melatonin rhythm associate with differences in sleep, and suggest that individuals with a long circadian period may be at risk of developing sleep problems.
Möller-Levet CS, Archer SN, Bucca G, Laing EE, Slak A, Kabiljo R, Lo JC, Santhi N, von Schantz M, Smith CP, Dijk DJ (2013) Effects of insufficient sleep on circadian rhythmicity and expression amplitude of the human blood transcriptome., Proc Natl Acad Sci U S A 110 (12) pp. E1132-E1141
Insufficient sleep and circadian rhythm disruption are associated with negative health outcomes, including obesity, cardiovascular disease, and cognitive impairment, but the mechanisms involved remain largely unexplored. Twenty-six participants were exposed to 1 wk of insufficient sleep (sleep-restriction condition 5.70 h, SEM = 0.03 sleep per 24 h) and 1 wk of sufficient sleep (control condition 8.50 h sleep, SEM = 0.11). Immediately following each condition, 10 whole-blood RNA samples were collected from each participant, while controlling for the effects of light, activity, and food, during a period of total sleep deprivation. Transcriptome analysis revealed that 711 genes were up- or down-regulated by insufficient sleep. Insufficient sleep also reduced the number of genes with a circadian expression profile from 1,855 to 1,481, reduced the circadian amplitude of these genes, and led to an increase in the number of genes that responded to subsequent total sleep deprivation from 122 to 856. Genes affected by insufficient sleep were associated with circadian rhythms (PER1, PER2, PER3, CRY2, CLOCK, NR1D1, NR1D2, RORA, DEC1, CSNK1E), sleep homeostasis (IL6, STAT3, KCNV2, CAMK2D), oxidative stress (PRDX2, PRDX5), and metabolism (SLC2A3, SLC2A5, GHRL, ABCA1). Biological processes affected included chromatin modification, gene-expression regulation, macromolecular metabolism, and inflammatory, immune and stress responses. Thus, insufficient sleep affects the human blood transcriptome, disrupts its circadian regulation, and intensifies the effects of acute total sleep deprivation. The identified biological processes may be involved with the negative effects of sleep loss on health, and highlight the interrelatedness of sleep homeostasis, circadian rhythmicity, and metabolism.
Von Schantz M, Jenkins A, Archer SN (2006) Evolutionary history of the vertebrate Period genes, Journal of Molecular Evolution 62 (6) pp. 701-707
Circadian clock genes are remarkably conserved between eucoelomates. Although Drosophila has one copy of each major component, vertebrates have two or (in the case of the Period genes) three paralogs (Per1-3). We investigated the possibility that the vertebrate Per genes arose through two genome duplications during the emergence of vertebrates. Phylogenetic trees have placed zebrafish and mammalian Per1 and 2 together in a separate branch from Per3. The positions of four coding region splice sites were conserved between Drosophila per and the human paralogs, the fifth one being unique to Drosophila. The human PER genes shared the positions of all coding region splice sites, except the first two in PER1 and PER2 (which PER3 lacks). The phases of all splice sites were conserved between all four genes with two exceptions. Analysis of all genes within 10 Mb of the human PER1-3 genes, which are located 7.8-8.8 Mb from the telomeres on chromosomes 17, 2, and 1, identified several orthologous neighbors shared by at least two PER genes. Two gene families, HES (hairy and Enhancer of Split) and KIF1 (kinesin-like protein 1), were represented in all three of these paralogons. Although no functional fourth human PER paralog exists, five representatives from the same gene families were found close to the telomer of chromosome 3. We conclude that the ancestral chordate Per gene underwent two duplication events, giving rise to Per1-3 and a lost fourth paralog. © Springer Science+Business Media, Inc. 2006.
Study Objectives: To screen the PER3 promoter for polymorphisms and investigate the phenotypic associations of these polymorphisms with diurnal preference, delayed sleep phase disorder/syndrome (DSPD/DSPS), and their effects on reporter gene expression.
Design: Interspecific comparison was used to define the approximate extent of the PER3 promoter as the region between the transcriptional start site and nucleotide position ?874. This region was screened in DNA pools using PCR and direct sequencing, which was also used to screen DNA from individual participants. The different promoter alleles were cloned into a luciferase expression vector and a deletion library created. Promoter activation was measured by chemiluminescence.
Patients or Participants: DNA samples were obtained from volunteers with defined diurnal preference (3 x 80, selected from a pool of 1,590), and DSPD patients (n = 23).
Measurements and Results: We verified three single nucleotide polymorphisms (G ?320T, C ?319A, G ?294A), and found a novel variable number tandem repeat (VNTR) polymorphism (?318 1/2 VNTR). The ?320T and ?319A alleles occurred more frequently in DSPD compared to morning (P = 0.042 for each) or evening types (P = 0.006 and 0.033). The allele combination TA2G was more prevalent in DSPD compared to morning (P = 0.033) or evening types (P = 0.002). Luciferase expression driven by the TA2G combination was greater than for the more common GC2A (P
Conclusions: Polymorphisms in the PER3 promoter could affect its expression, leading to potential differences in the observed functions of PER3.
Archer S, Viola A, Von Schantz M, Dijk D (2007) Endogenous circadian rhythm of PER3 RNA in human leucocytes: Association with sleep timing, melatonin rhythm, and PER3 genotype, SLEEP 30 pp. A54-A55 AMER ACADEMY SLEEP MEDICINE
The relationship between diurnal preference, as measured by the Horne-Ostberg questionnaire, and quantifiable personality traits was investigated in 617 participants. A hierarchical multiple regression analysis demonstrated that out of the personality variables, conscientiousness was the single biggest predictor of diurnal preference (beta=0.246), after controlling for depression, sleep disorders, shift work, age, gender, and demographic characteristics. Morningness has previously been associated with physiological parameters of the circadian clock and with polymorphisms in circadian clock genes, suggesting the possibility that conscientiousness, too, may be linked to the same parameters.
von Schantz M, Provencio I, Foster RG (2000) Recent developments in circadian photoreception: More than meets the eye, INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE 41 (7) pp. 1605-1607 ASSOC RESEARCH VISION OPHTHALMOLOGY INC
Jones KHS, Ellis J, Von Schantz M, Skene DJ, Dijk D-J, Archer SN (2007) Age-related change in the association between a polymorphism in the PER3 gene and preferred timing of sleep and waking activities, JOURNAL OF SLEEP RESEARCH 16 (1) pp. 12-16 BLACKWELL PUBLISHING
Lo JC, Groeger JA, Santhi N, Arbon EL, Lazar AS, Hasan S, Von Schantz M, Archer SN, Dijk DJ (2012) Effects of circadian phase and prior partial sleep deprivation on executive functions during total sleep deprivation are modulated by PER3 polymorphism, JOURNAL OF SLEEP RESEARCH 21 pp. 41-41 WILEY-BLACKWELL
Archer SN, Thompson S, Lucas RJ, Foster RG, von Schantz M (2000) Analysis of differentially expressed genes in the wildtype and rd mouse retina by macroarray screening., INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE 41 (4) pp. S27-S27 ASSOC RESEARCH VISION OPHTHALMOLOGY INC
von Schantz M, Szel A, van Veen T, Farber DB (1998) Cloning of a cyclic GMP phosphodiesterase gamma subunit from the ground squirrel retina, MOLECULAR BRAIN RESEARCH 54 (2) pp. 327-333 ELSEVIER SCIENCE BV
Viola AU, Archer SN, James LM, Groeger JA, Lo JCY, Skene DJ, von Schantz M, Dijk D-J (2007) PER3 polymorphism predicts sleep structure and waking performance, CURRENT BIOLOGY 17 (7) pp. 613-618 CELL PRESS
Carpen JD, Archer SN, Skene DJ, Smits M, von Schantz M (2005) A single-nucleotide polymorphism in the 5 '-untranslated region of the hPER2 gene is associated with diurnal preference, JOURNAL OF SLEEP RESEARCH 14 (3) pp. 293-297 BLACKWELL PUBLISHING
Martynhak BJ, Hogben AL, Zanos P, Georgiou P, Andreatini R, Kitchen I, Archer SN, von Schantz M, Bailey A, Van Der Veen DR (2017) Transient anhedonia phenotype and altered circadian timing of behaviour during night-time dim light exposure in Per3-/- mice, but not wildtype mice, Scientific Reports 7 40399
Nature Publishing Group
Industrialisation greatly increased human night-time exposure to artificial light, which in animal models is a known cause of depressive phenotypes. Whilst many of these phenotypes are ?direct? effects of light on affect, an ?indirect? pathway via altered sleep-wake timing has been suggested. We have previously shown that the Period3 gene, which forms part of the biological clock, is associated with altered sleep-wake patterns in response to light. Here, we show that both wild-type and Per3-/- mice showed elevated levels of circulating corticosterone and increased hippocampal Bdnf expression after 3 weeks of exposure to dim light at night, but only mice deficient for the PERIOD3 protein (Per3-/-) exhibited a transient anhedonia-like phenotype, observed as reduced sucrose preference, in weeks 2-3 of dim light at night, whereas WT mice did not. Per3-/- mice also exhibited a significantly smaller delay in behavioural timing than WT mice during weeks 1, 2 and 4 of dim light at night exposure. When treated with imipramine, neither Per3-/- nor WT mice exhibited an anhedonia-like phenotype, and neither genotypes exhibited a delay in behavioural timing in responses to dLAN. While the association between both Per3-/- phenotypes remains unclear, both are alleviated by imipramine treatment during dim night-time light.
Gao N, von Schantz M, Foster RG, Hardie J (1999) The putative brain photoperiodic photoreceptors in the vetch aphid, Megoura viciae, JOURNAL OF INSECT PHYSIOLOGY 45 (11) pp. 1011-1019 PERGAMON-ELSEVIER SCIENCE LTD
Ahuja P, Archer SN, van Veen T, von Schantz M (2003) Neuroleukin/AMF is present around cones and in various spatially restricted cell types of the mouse retina, INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE 44 pp. U459-U459 ASSOC RESEARCH VISION OPHTHALMOLOGY INC
Lazar A, Santhi N, Lo J, Slak A, Hasan S, Von Schantz M, Archer S, Dijk D-J (2012) The circadian and homeostatic regulation of sleep spindle activity: effect of the PER3 VNTR polymorphism, JOURNAL OF SLEEP RESEARCH 21 pp. 82-82 WILEY-BLACKWELL
Viola AU, Archer SN, Groeger JA, Skene DJ, Von Schantz M, Dijk DJ (2006) Polymorphism in the clock gene PER3 predicts sleep structure and EEG power spectra, JOURNAL OF SLEEP RESEARCH 15 pp. 53-53 BLACKWELL PUBLISHING
Lázár AS, Slak A, Lo JC, Santhi N, von Schantz M, Archer SN, Groeger JA, Dijk DJ (2012) Sleep, diurnal preference, health, and psychological well-being: a prospective single-allelic-variation study., Chronobiol Int 29 (2) pp. 131-146
Individual differences in sleep and diurnal preference associate with physical and mental health characteristics, but few genetic determinants of these differences have been identified. A variable number tandem repeat (VNTR) polymorphism in the PERIOD3 (PER3) gene (rs57875989) has been reported to associate with diurnal preference, i.e., preferred timing of waking and sleep. Here, the authors investigate in a prospective single-candidate genetic variant study whether allelic variation for this polymorphism associates also with reported actual sleep timing and sleep duration, as well as psychological and health measures. Six hundred and seventy-five subjects, aged 20 to 35 yrs, completed questionnaires to assess sleep and psychological and health characteristics and were genotyped for the PER3 VNTR. Homozygosity for the longer allele (PER3(5/5)) of the VNTR was associated with increased morning preference, earlier wake time and bedtime, and reduced daytime sleepiness. Separate analyses of work and rest days demonstrated that the increase in time in bed during rest days was greatest in PER3(5/5) homozygotes. PER3 genotype modified the effects of sleep timing and duration on fluid intelligence and body mass index. Genotype was not associated with physical or psychological characteristics as assessed by the SF-36 Health Questionnaire, the General Health Questionnaire, the Big Five Inventory, the Behavioral Inhibition System-Behavioral Activation System scales, and the Positive and Negative Affect Scale, even though these measures varied significantly with diurnal preference as assessed by the Morningness-Eveningness Questionnaire. Whereas diurnal preference also predicts mental health and psychological characteristics, as well as sleep timing, the PER3 VNTR specifically affects measures of sleep timing and may also modify the effects of sleep on health outcome measures.
von Schantz M, Lucas RJ, Foster RG (1999) Circadian oscillation of photopigment transcript levels in the mouse retina, MOLECULAR BRAIN RESEARCH 72 (1) pp. 108-114 ELSEVIER SCIENCE BV
Lockley SW, Skene DJ, Thapan K, English J, Ribeiro D, Haimov I, Hampton S, Middleton B, von Schantz M, Arendt J (1998) Extraocular light exposure does not suppress plasma melatonin in humans, JOURNAL OF CLINICAL ENDOCRINOLOGY & METABOLISM 83 (9) pp. 3369-3372
Groeger JA, Lo JC, Santhi N, Arbon EL, Lazar A, Hasan S, Von Schantz M, Archer SN, Dijk DJ (2012) 'Trait-like' susceptibility to sleep loss varies with circadian phase and the task used to index vulnerable-resilient sleep-deprived performance, JOURNAL OF SLEEP RESEARCH 21 pp. 36-37 WILEY-BLACKWELL
Von Schantz M, Archer SN (2006) Genetic aspects of delayed sleep phase syndrome (DSPS), JOURNAL OF SLEEP RESEARCH 15 pp. 5-5 BLACKWELL PUBLISHING
Archer SN, Laing EE, Moller-Levet CS, van der Veen DR, Bucca G, Lazar AS, Lo JCY, Santhi N, Slak A, Kabiljo R, von Schantz M, Smith CP, Dijk DJ (2014) Mistimed sleep disrupts the circadian regulation of the human transcriptome, JOURNAL OF SLEEP RESEARCH 23 pp. 15-15 WILEY-BLACKWELL
The aim of this study was to analyse the circadian behavioural responses of mice carrying a functional knockout of the Per3 gene (P e r 3 - / -) to different light: dark (L: D) cycles. Male adult wild-type (WT) and P e r 3 - / - mice were kept under 12-hour light: 12-hour dark conditions (12L: 12D) and then transferred to either a short or long photoperiod and subsequently released into total darkness. All mice were exposed to both conditions, and behavioural activity data were acquired through running wheel activity and analysed for circadian characteristics during these conditions. We observed that, during the transition from 12L: 12D to 16L: 8D, P e r 3 - / - mice take approximately one additional day to synchronise to the new L: D cycle compared to WT mice. Under these long photoperiod conditions, P e r 3 - / - mice were more active in the light phase. Our results suggest that P e r 3 - / - mice are less sensitive to light. The data presented here provides further evidence that Per3 is involved in the suppression of behavioural activity in direct response to light. © 2014 D. S. Pereira et al.
Groeger JA, Viola AU, Lo JCY, von Schantz M, Archer SN, Dijk D-J (2008) Early morning executive functioning during sleep deprivation is compromised by a PERIOD3 polymorphism, SLEEP 31 (8) pp. 1159-1167 AMER ACAD SLEEP MEDICINE
von Schantz M, Archer SN (2003) Clocks, genes and sleep, JOURNAL OF THE ROYAL SOCIETY OF MEDICINE 96 (10) pp. 486-489 ROYAL SOC MEDICINE PRESS LTD
Groeger J, Lo J, Viola A, Von Schantz M, Archer S, Dijk D (2007) PER3 polymorphism predictssusceptibility to sleep deprivation-induced impairment of early morning executive performance, SLEEP 30 pp. A54-A54 AMER ACADEMY SLEEP MEDICINE
von Schantz M, Skene DJ (2015) Telling biological time from a blood sample - current capabilities and future potential, In: Annals of Clinical Biochestry SAGE
Circadian rhythms, near-24 h oscillations that reflect homeostatic control by an internal timing system rather than the influence of external factors, are an important and sometimes underappreciated aspect of human physiology and biochemistry. Over the past few decades, the pineal gland hormone melatonin has been established both as a robust marker of circadian phase in plasma or saliva, and as a chronobiotic drug administered to reset the timing of the circadian oscillator. Recent work by our own and other laboratories has sought to systematically investigate whole categories of molecular components in blood samples in a hypothesis-free fashion by employing metabolomic methodologies to study low-molecular-weight compounds and transcriptomic methodologies to study gene expression in white blood cells, respectively. A number of components have been pinpointed that show a rhythmic circadian variation or are affected by imposed factors such as sleep deprivation. Although melatonin, a robust and reliable circadian phase marker, will be a hard act to follow, these lines of research suggest numerous potential leads for useful new markers of biological timing.
Study Objectives: Individual sleep timing differs and is governed partly by
circadian oscillators, which may be assessed by hormonal markers, or by clock
gene expression. Clock gene expression oscillates in peripheral tissues, including
leukocytes. The study objective was to determine whether the endogenous phase
of these rhythms, assessed in the absence of the sleep-wake and light-dark
cycle, correlates with habitual sleep-wake timing.
Design: Observational, cross-sectional.
Setting: Home environment and Clinical Research Center.
Participants: 24 healthy subjects aged 25.0 ± 3.5 (SD) years.
Measurements: Actigraphy and sleep diaries were used to characterize sleep
timing. Circadian rhythm phase and amplitude of plasma melatonin, cortisol, and
BMAL1, PER2, and PER3 expression were assessed during a constant routine.
Results: Circadian oscillations were more robust for PER3 than for BMAL1 or PER2.
Average peak timings were 6:05 for PER3, 8:06 for PER2, 15:06 for BMAL1, 4:20 for
melatonin, and 10:49 for cortisol. Individual sleep-wake timing correlated with the
phases of melatonin and cortisol. Individual PER3 rhythms correlated significantly
with sleep-wake timing and the timing of melatonin and cortisol, but those of PER2
and BMAL1 did not reach significance. The correlation between sleep timing and
PER3 expression was stronger in individuals homozygous for the variant of the
PER3 polymorphism that is associated with morningness.
Conclusions: Individual phase differences in PER3 expression during a constant
routine correlate with sleep timing during entrainment. PER3 expression in
leukocytes represents a useful molecular marker of the circadian processes
governing sleep-wake timing.
Archer SN, Laing EE, Möller-Levet CS, van der Veen DR, Bucca G, Lazar AS, Santhi N, Slak A, Kabiljo R, von Schantz M, Smith CP, Dijk DJ (2014) Mistimed sleep disrupts circadian regulation of the human transcriptome., Proc Natl Acad Sci U S A
Circadian organization of the mammalian transcriptome is achieved by rhythmic recruitment of key modifiers of chromatin structure and transcriptional and translational processes. These rhythmic processes, together with posttranslational modification, constitute circadian oscillators in the brain and peripheral tissues, which drive rhythms in physiology and behavior, including the sleep-wake cycle. In humans, sleep is normally timed to occur during the biological night, when body temperature is low and melatonin is synthesized. Desynchrony of sleep-wake timing and other circadian rhythms, such as occurs in shift work and jet lag, is associated with disruption of rhythmicity in physiology and endocrinology. However, to what extent mistimed sleep affects the molecular regulators of circadian rhythmicity remains to be established. Here, we show that mistimed sleep leads to a reduction of rhythmic transcripts in the human blood transcriptome from 6.4% at baseline to 1.0% during forced desynchrony of sleep and centrally driven circadian rhythms. Transcripts affected are key regulators of gene expression, including those associated with chromatin modification (methylases and acetylases), transcription (RNA polymerase II), translation (ribosomal proteins, initiation, and elongation factors), temperature-regulated transcription (cold inducible RNA-binding proteins), and core clock genes including CLOCK and ARNTL (BMAL1). We also estimated the separate contribution of sleep and circadian rhythmicity and found that the sleep-wake cycle coordinates the timing of transcription and translation in particular. The data show that mistimed sleep affects molecular processes at the core of circadian rhythm generation and imply that appropriate timing of sleep contributes significantly to the overall temporal organization of the human transcriptome.
von Schantz M, Archer SN, Ahuja P, van Veen T (2002) Identification of transcripts enriched in the inner retina by differential macroarray hybridization, INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE 43 pp. U321-U321 ASSOC RESEARCH VISION OPHTHALMOLOGY INC
Egan K, Campos Santos H, Beijamini F, Duarte N, Horimoto A, Taporoski T, Vallada H, Negrão A, Krieger J, Pedrazzoli M, Knutson K, Pereira A, von Schantz M (2017) Amerindian (but not African or European) ancestry is significantly associated with diurnal preference within an admixed Brazilian population, Chronobiology International: the journal of biological and medical rhythm research 34 (2) pp. 269-272
Taylor & Francis
Significant questions remain unanswered regarding the genetic versus environmental contributions to racial/ethnic differences in sleep and circadian rhythms. We addressed this question by investigating the association between diurnal preference, using the Morningness-Eveningness questionnaire (MEQ), and genetic ancestry within the Baependi Heart Study cohort, a highly admixed Brazilian population based in a rural town. Analysis was performed using measures of ancestry, using the Admixture program, and MEQ from 1,453 individuals. We found an association between the degree of Amerindian (but not European of African) ancestry and morningness, equating to 0.16 units for each additional percent of Amerindian ancestry, after adjustment for age, sex, education, and residential zone. To our knowledge, this is the first published report identifying an association between genetic ancestry and MEQ, and above all, the first one based on ancestral contributions within individuals living in the same community. This previously unknown ancestral dimension of diurnal preference suggests a stratification between racial/ethnic groups in an as yet unknown number of genetic polymorphisms.
Jenkins A, Archer SN, von Schantz M (2005) Expansion during primate radiation of a variable number tandem repeat in the coding region of the circadian clock gene Period3, JOURNAL OF BIOLOGICAL RHYTHMS 20 (5) pp. 470-472 SAGE PUBLICATIONS LTD
Dijk DJ, von Schantz M (2005) Timing and consolidation of human sleep, wakefulness, and performance by a symphony of oscillators, JOURNAL OF BIOLOGICAL RHYTHMS 20 (4) pp. 279-290 SAGE PUBLICATIONS INC
Lo JC, Groeger JA, Santhi N, Arbon EL, Lazar AS, Hasan S, von Schantz M, Archer SN, Dijk DJ (2012) Effects of partial and acute total sleep deprivation on performance across cognitive domains, individuals and circadian phase., PLoS One 7 (9)
Cognitive performance deteriorates during extended wakefulness and circadian phase misalignment, and some individuals are more affected than others. Whether performance is affected similarly across cognitive domains, or whether cognitive processes involving Executive Functions are more sensitive to sleep and circadian misalignment than Alertness and Sustained Attention, is a matter of debate.
Robilliard DL, Archer SN, Arendt J, Lockley SW, Hack LM, English J, Leger D, Smits MG, Williams A, Skene DJ, von Schantz M (2002) The 3111 Clock gene polymorphism is not associated with sleep and circadian rhythmicity in phenotypically characterized human subjects, JOURNAL OF SLEEP RESEARCH 11 (4) pp. 305-312 BLACKWELL PUBLISHING LTD
Archer SN, Lucas RJ, Thompson S, Foster RG, von Schantz M (2002) Identification of a novel retinal kinase with promoter elements affected by circadian clock proteins, INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE 43 pp. U308-U308 ASSOC RESEARCH VISION OPHTHALMOLOGY INC
von Schantz M, Jenkins A, Archer SN (2006) Evolutionary history of the vertebrate Period genes, JOURNAL OF MOLECULAR EVOLUTION 62 (6) pp. 701-707 SPRINGER
Archer SN, Ahuja P, Caffe R, Mikol C, Foster RG, van Veen T, von Schantz M (2004) Absence of phosphoglucose isomerase-1 in retinal photoreceptor, pigment epithelium and Muller cells, EUROPEAN JOURNAL OF NEUROSCIENCE 19 (11) pp. 2923-2930 BLACKWELL PUBLISHING LTD
Nadkarni NA, Weale ME, von Schantz M, Thomas MG (2005) Evolution of a length polymorphism in the human PER3 gene, a component of the circadian system, JOURNAL OF BIOLOGICAL RHYTHMS 20 (6) pp. 490-499 SAGE PUBLICATIONS INC
Taporoski TP, Negrao AB, Horimoto ARVR, Duarte NE, Alvim RO, de Oliveira CM, Krieger JE, von Schantz M, Vallada H, Pereira AC (2015) Shared Genetic Factors of Anxiety and Depression Symptoms in a Brazilian Family-Based Cohort, the Baependi Heart Study, PLOS ONE 10 (12) ARTN e0144255 PUBLIC LIBRARY SCIENCE
Freedman MS, Lucas RJ, Soni B, von Schantz M, Munoz M, David-Gray Z, Foster R (1999) Regulation of mammalian circadian behavior by non-rod, non-cone, ocular photoreceptors, SCIENCE 284 (5413) pp. 502-504 AMER ASSOC ADVANCEMENT SCIENCE
Beijamini F, Knutson K, Lorenzi-Filho G, Egan K, Taporoski T, De Paula L, Negrão A, Horimoto A, Duarte N, Vallada H, Krieger J, Pedrazzoli M, Pereira A, von Schantz M (2016) Timing and quality of sleep in a rural Brazilian family-based cohort, the Baependi Heart Study, Scientific Reports 6 39283 pp. 1-9
Nature Publishing Group
Sleep is modulated by several factors, including sex, age, and chronotype. It has been hypothesised that contemporary urban populations are under pressure towards shorter sleep duration and poorer sleep quality. Baependi is a small town in Brazil that provides a window of opportunity to study the influence of sleep patterns in a highly admixed rural population with a conservative lifestyle. We evaluated sleep characteristics, excessive daytime sleepiness, and chronotype using the Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale and Morningness-Eveningness Questionnaire questionnaires, respectively. The sample consisted of 1,334 subjects from the Baependi Heart study (41.5% male; age: 46.5±16.2 y, range: 18?89 years). Average self-reported sleep duration was 07:07±01:31 (bedtime 22:32±01:27, wake up time: 06:17±01:25 hh:min), sleep quality score was 4.9+3.2, chronotype was 63.6±10.8 and daytime sleepiness was 7.4±4.8. Despite a shift towards morningness in the population, chronotype remained associated with reported actual sleep timing. Age and sex modulated the ontogeny of sleep and chronotype, increasing age was associated with earlier sleep time and shorter sleep duration. Women slept longer and later, and reported poorer sleep quality than men (p
Our own species has a diurnal activity pattern and an average circadian period of 24.2 hours. Exact determination of circadian period requires expensive and intrusive protocols, and investigators are therefore using chronotype questionnaires as a proxy quantitative measure. Both measures show a normal distribution suggestive of a polygenic trait. The genetic components of the 24-hour feedback loop that generates circadian rhythms within our cells have been mapped in detail, identifying a number of candidate genes which have been investigated for genetic polymorphisms relating to the phenotypic variance. Key in this mechanism is the inhibitory complex containing period and cryptochrome proteins and interacting protein kinases and ubiquitin ligases, and the stability of this complex is recognized as the major determinant of circadian periodicity. The identification of the causative mutations in familial circadian rhythms sleep disorders has shed additional light into this mechanism. Mutations in the negative feedback protein-encoding genes PER2 and CRY2 as well as the CSNK1D gene encoding casein kinase I delta have been shown to cause advanced sleep phase disorder, and a mutation in the CRY1 gene delayed sleep phase disorder. The candidate gene approach has also yielded a number of genetic associations with chronotype as determined by questionnaires. More recently, genome-wide association studies (GWAS) of chronotype have both confirmed associations with the candidate clock gene PER2 and identified a serious of novel genes associated with variability in circadian rhythmicity, which have yet to be explored. Whilst considerable progress has thus been made with mapping the phenotypic diversity in human circadian rhythms and the genomic variability that causes it, studies to date have been mostly focused on individuals of European descent, and there is a strong need for research on other populations.
Beale A, Pedrazzoli M, Gonçalves B, Beijamini F, Duarte N, Egan K, Knutson K, von Schantz M, Roden L (2017) Comparison between an African town and a neighbouring village shows delayed, but not decreased, sleep during the early stages of urbanisation, Scientific Reports 7 5697
NATURE PUBLISHING GROUP
The well-established negative health outcomes of sleep deprivation, and the suggestion that
availability of electricity may enable later bed times without compensating sleep extension in the
morning, have stimulated interest in studying communities whose sleep pattern may resemble a preindustrial
state. Here, we describe sleep and activity in two neighbouring communities, one urban
(Milange) and one rural (Tengua), in a region of Mozambique where urbanisation is an ongoing process.
The two communities differ in the amount and timing of daily activity and of light exposure, with later
bedtimes (H1 h) associated with more evening and less daytime light exposure seen in the town of
Milange. In contrast to previous reports comparing communities with and without electricity, sleep
duration did not differ between Milange (7.28 h) and Tengua (7.23 h). Notably, calculated sleep quality
was significantly poorer in rural Tengua than in Milange, and poor sleep quality was associated with
a number of attributes more characteristic of rural areas, including more intense physical labour and
less comfortable sleeping arrangements. Thus, whilst our data support the hypothesis that access to
electricity delays sleep timing, the higher sleep quality in the urban population also suggests that some
aspects of industrialisation are beneficial to sleep.
Henslee Erin, Crosby Priya, Kitcatt Stephen, Parry Jack S. W., Bernardini Andrea, Abdallat Rula G., Braun Gabriella, Fatoyinbo Henry O., Harrison Esther J., Edgar Rachel S., Hoettges Kai, Reddy Akhilesh B., Jabr Rita, von Schantz Malcolm, O?Neill John S., Labeed Fatima (2017) Rhythmic potassium transport regulates the circadian clock in human red blood cells, Nature Communications 8 1978(2017)
Nature Publishing Group
Circadian rhythms organize many aspects of cell biology and physiology to a daily temporal program that depends on clock gene expression cycles in most mammalian cell types. However, circadian rhythms are also observed in isolated mammalian red blood cells (RBCs), which lack nuclei, suggesting the existence of post-translational cellular clock mechanisms in these cells. By using electrophysiological and pharmacological approaches, we show that human RBCs display circadian regulation of membrane conductance and cytoplasmic conductivity that depends on the cycling of cytoplasmic K+ levels. Using pharmacological intervention and ion replacement, we show that inhibition of K+ transport abolishes RBC electrophysiological rhythms. Our results suggest that in the absence of conventional transcription cycles, RBCs maintain a circadian rhythm in membrane electrophysiology through dynamic regulation of K+ transport.
Later chronotype (i.e. evening preference) and later timing of sleep have been associated with greater
morbidity, including higher rates of metabolic dysfunction and cardiovascular disease. However, no one has
examined whether chronotype is associated with mortality risk to date. Our objective was to test the
hypothesis that being an evening type is associated with increased mortality in a large cohort study, the UK
Biobank. Our analysis included 433,268 adults aged 38-73 at the time of enrolment and an average 6.5-
year follow-up. The primary exposure was chronotype, as assessed through a single self-reported question
defining participants as definite morning types, moderate morning types, moderate evening types, or
definite evening types. The primary outcomes were all-cause mortality and mortality due to cardiovascular
disease (CVD). Prevalent disease was also compared among the chronotype groups. Analyses were
adjusted for age, sex, ethnicity, smoking, body mass index, sleep duration, socioeconomic status and
comorbidities. Greater eveningness, particularly being a definite evening type, was significantly associated
with a higher prevalence of all comorbidities. Comparing definite evening type to definite morning type, the
associations were strongest for psychological disorders (OR 1.94, 95% CI 1.86 to 2.02, p=<.001 followed="">
by diabetes (OR 1.30, 95% CI 1.24 to 1.36, p=<.001 neurological="" disorders="" ci="" to="">
1.30, p=<.001 gastrointestinal="" abdominal="" disorders="" ci="" to="" p="<.001)," and="">
respiratory disorders (OR 1.22, 95% CI 1.18 to 1.26, p=<.001 the="" total="" number="" of="" deaths="" was="" out="">
of which 2,127 were due to CVD. Greater eveningness, based on chronotype as an ordinal variable, was
associated with a small increased risk of all-cause mortality (HR 1.02, 95% CI 1.004 to 1.05, p=.017) and
CVD mortality (HR 1.04, 95% CI 1.00 to 1.09, p=.06). Compared to definite morning types, definite evening
types had significantly increased risk of all-cause mortality (HR 1.10, 95% CI 1.02 to 1.18, p=.012). This
first report of increased mortality in evening types is consistent with previous reports of increased levels of
cardiometabolic risk factors in this group. Mortality risk in evening types may be due to behavioural,
psychological, and physiological risk factors, many of which may be attributable to chronic misalignment
between internal physiological timing and externally imposed timing of work and social activities. These
findings suggest the need for researching possible interventions aimed at either modifying circadian
rhythms in individuals or at allowing evening types greater working hour flexibility.
Circadian rhythms and sleep are two separate but intimately related processes. Circadian rhythms are generated through the precisely controlled, cyclic expression of a number of genes designated clock genes. Genetic variability in these genes has been associated with a number of phenotypic differences in circadian, but also in sleep parameters both in mouse models and in humans. Diurnal preferences, as determined by the self-reported Horne-Östberg questionnaire, has been associated with polymorphisms in the human genes CLOCK, PER1, PER2, and PER3. Circadian rhythms sleep disorders have also been associated with mutations and polymorphisms in clock genes, with the advanced type cosegrating in an autosomal dominant inheritance pattern with mutations in the genes PER2 and CSNK1D, and the delayed type associating without discernible Mendelian inheritance with polymorphisms in CLOCK and PER3. Several mouse models of clock gene null alleles have been demonstrated to have affected sleep homeostasis. Recent findings have shown that the variable number tandem polymorphism in PER3, previously linked to diurnal preference, has profound effects on sleep homeostasis and cognitive performance following sleep loss, confirming the close association between the processes of circadian rhythms and sleep on the genetic level.
In recent years, strong evidence has emerged suggesting that insufficient duration, quality, and/or timing of sleep are associated with cardiovascular disease (CVD), and various mechanisms for this association have been proposed. Such associations may be related to endophenotypic features of the sleep homeostat and the circadian oscillator, or may be state-like effects of the environment. Here, we review recent literature on sleep, circadian rhythms and CVD with a specific emphasis on differences between racial/ethnic groups. We discuss the reported differences, mainly between individuals of European and African descent, in parameters related to sleep (architecture, duration, quality) and circadian rhythms (period length and phase shifting). We further review racial/ethnic differences in cardiovascular disease and its risk factors, and develop the hypothesis that racial/ethnic health disparities may, to a greater or smaller degree, relate to differences in parameters related to sleep and circadian rhythms. When humans left Africa some 100,000 years ago, some genetic differences between different races/ethnicities were acquired. These genetic differences have been proposed as a possible predictor of CVD disparities, but concomitant differences in culture and lifestyle between different groups may equally explain CVD disparities. We discuss the evidence for genetic and environmental causes of these differences in sleep and circadian rhythms, and their usefulness as health intervention targets.
In spite of suspected circadian differences between different ancestral groups, most human studies have used individuals of European descent. This also applies to three recent genome-wide association studies (GWAS), which pinpointed a number of chronotype loci. We investigated the distribution of these hits in different 1000 Genomes populations. We found six out of the 41 alleles previously identified by GWAS in European participants (in the genes RGS16, PER2, AK5, and between the genes APH1A and CA14) to be absent from some non-European population groups. This highlights the need for ancestral diversity in circadian research, and may reflect differences affecting the phenotype of individuals of East Asian ancestry.
As part of the Health and Aging in Africa: A Longitudinal Study of an INDEPTH Community in
South Africa (HAALSI), we investigated sleep habits and their interactions with HIV or noncommunicable
diseases (NCDs) in 5059 participants (median age: 61, interquartile range:
52?71, 54% females). Self-reported sleep duration was 8.2±1.6h, and bed and rise times
were 20:48±1:15 and 05:31±1:05 respectively. Ratings of insufficient sleep were associated
with older age, lack of formal education, unemployment, and obesity (p
restless sleep were associated with being older, female, having more education, being
unemployed, and single. Hypertension was associated with shorter self-reported sleep
duration, poor sleep quality, restless sleep, and periods of stopping breathing during the
nocturnal awakenings than those on ART (p=0.029) and HIV negative individuals (p=0.024),
suggesting a negative net effect of untreated infection, but not of ART, on sleep quality. In
this cohort, shorter, poor-quality sleep was associated with hypertension, but average self-reported
sleep duration was longer than reported in other regions globally. It remains to be
determined whether this is particular to this cohort, South Africa in general, or low- to
middle-income countries undergoing transition.
Geovanini Glaucylara Reis, Lorenzi-Filho Geraldo, de Paula Lilian K, Oliveira Camila M, Alvim Rafael O, Beijamini Felipe, Negrão André B, von Schantz Malcolm, Knutson Kristen L, Krieger José E, Pereira Alexandre C (2019) Poor Sleep Quality and Lipid Profile in a Rural Cohort (The Baependi Heart Study)., Sleep Medicine 57 pp. 30-35
Aim: To test the association between cardiometabolic risk factors and
subjective sleep quality assessed by the Pittsburgh sleep quality index
(PSQI), independent of obstructive sleep apnea (OSA) and sleep duration.
Methods: 573 participants from the Baependi Heart Study, a rural cohort
from Brazil that completed sleep questionnaires and underwent polygraphy
for OSA evaluation. Multivariable linear regression analysis tested the
association between cardiovascular risk factors (outcome variables) and
sleep quality measured by PSQI, adjusting for OSA and other potential
confounders (age, sex, race, salary/wage, education, marital status,
alcohol intake, obesity, smoking, hypertension, and sleep duration).
Results: The sample mean age was of 43±16y, 66% were female, and mean
body mass index (BMI) was 26±5 kg/m2. Only 20% were classified as obese
(BMI e30). Fifty percent of participants reported poor sleep quality as
defined by a PSQI score e5. A high PSQI score was significantly
associated with higher very-low density lipoprotein (VLDL) cholesterol
levels (beta=0.392, p=0.012) and higher triglyceride levels (beta=0.017,
p=0.006), even after adjustments, including the apnea-hypopnea index.
Further adjustments accounting for marital status, alcohol intake, and
medication use did not change these findings. No significant association
was observed between PSQI scores and glucose or blood pressure. According
to PSQI components, sleep disturbances (beta=1.976, p=0.027), sleep
medication use (beta=1.121, p=0.019), and daytime dysfunction
(beta=1.290, p=0.024) were significantly associated with higher VLDL
serum levels. Only the daytime dysfunction domain of the PSQI components
was significantly associated with higher triglyceride levels (beta=0.066,
Conclusion: Poorer lipid profile was independently associated with poor
sleep quality, assessed by the PSQI questionnaire, regardless of a normal
sleep duration and accounting for OSA and socio-economic status.
Alkan Erkan, Taporoski T P, Sterr A, von Schantz M, Vallada H, Krieger J E, Pereira A C, Alvim R, Horimoto A R V R, Pompéia S, Negrão A B, Evans Simon (2019) Metabolic syndrome alters relationships between cardiometabolic variables, cognition and white matter hyperintensity load, Scientific Reports 9 4356
Nature Publishing Group
Cardiometabolic risk factors influence white matter hyperintensity (WMH) development: in metabolic syndrome (MetS), higher WMH load is often reported but the relationships between specific cardiometabolic variables, WMH load and cognitive performance are uncertain. We investigated these in a Brazilian sample (aged 50-85) with (N=61) and without (N=103) MetS. Stepwise regression models identified effects of cardiometabolic and demographic variables on WMH load (from FLAIR MRI) and verbal recall performance. WMH volume was greater in MetS, but verbal recall performance was not impaired. Age showed the strongest relationship with WMH load. Across all participants, systolic blood pressure (SBP) and fasting blood glucose were also contributors, and WMH volume was negatively associated with verbal recall performance. In non-MetS, higher HbA1c, SBP, and number of MetS components were linked to poorer recall performance while higher triglyceride levels appeared to be protective. In MetS only, these relationships were absent but education exerted a strongly protective effect on recall performance. Thus, results support MetS as a construct: the clustering of cardiometabolic variables in MetS alters their individual relationships with cognition; instead, MetS is characterised by a greater reliance on cognitive reserve mechanisms. In non-MetS, strategies to control HbA1c and SBP should be prioritised as these have the largest impact on cognition.
Beale Andrew D., Kruchek Emily, Kitcatt Stephen J., Henslee Erin A., Parry Jack S.W., Braun Gabriella, Jabr Rita, von Schantz Malcolm, O?Neill John S., Labeed Fatima H. (2019) Casein kinase 1 underlies temperature compensation of circadian rhythms in human red blood cells, Journal of Biological Rhythms
Temperature compensation and period determination by casein kinase 1 (CK1) are conserved features of eukaryotic circadian rhythms, whereas the clock gene transcription factors that facilitate daily gene expression rhythms differ between phylogenetic kingdoms. Human red blood cells (RBCs) exhibit temperature compensated circadian rhythms which, since RBCs lack nuclei, must occur in the absence of a circadian transcription-translation feedback loop. We tested whether period determination and temperature compensation are dependent on casein kinases in RBCs. As with nucleated cell types, broad spectrum kinase inhibition with staurosporine lengthened the period of the RBC clock at 37°C, with more specific inhibition of CK1 and CK2 also eliciting robust changes in circadian period. Strikingly, inhibition of CK1 abolished temperature compensation and increased the Q10 for the period of oscillation in RBCs, similar to observations in nucleated cells. This indicates that CK1 activity is essential for circadian rhythms irrespective of the presence or absence of clock gene expression cycles.
Taporoski T. P., Duarte N.E., Pompéia S., Sterr A., Gómez L.M., Alvim R.O., Horimoto A.R.V.R., Krieger J.E., Vallada H., Pereira A.C., von Schantz M., Negrão A.B. (2019) Heritability of semantic verbal fluency task using time-interval analysis, PLOS ONE 14 (6) e0217814 pp. 1-13
Public Library of Science
Individual variability in word generation is a product of genetic and environmental influences. The genetic effects on semantic verbal fluency were estimated in 1,735 participants from the Brazilian Baependi Heart Study. The numbers of exemplars produced in 60 s were broken down into time quartiles because of the involvement of different cognitive processes ? predominantly automatic at the beginning, controlled/executive at the end. Heritability in the unadjusted model for the 60-s measure was 0.32. The best-fit model contained age, sex, years of schooling, and time of day as covariates, giving a heritability of 0.21. Schooling had the highest moderating effect. The highest heritability (0.17) was observed in the first quartile, decreasing to 0.09, 0.12, and 0.0003 in the following ones. Heritability for average production starting point (intercept) was 0.18, indicating genetic influences for automatic cognitive processes. Production decay (slope), indicative of controlled processes, was not significant. The genetic influence on different quartiles of the semantic verbal fluency test could potentially be exploited in clinical practice and genome-wide association studies.
Beale Andrew D., Kruchek Emily, Kitcatt Stephen J., Henslee Erin A., Parry Jack S.W., Braun Gabriella, Jabr Rita, von Schantz Malcolm, O?Neill John S., Labeed Fatima (2019) Casein Kinase 1 Underlies Temperature Compensation of Circadian Rhythms in Human Red Blood Cells, Journal of Biological Rhythms 34 (2) pp. 144-153
Temperature compensation and period determination by casein kinase 1 (CK1) are conserved features of eukaryotic circadian rhythms, whereas the clock gene transcription factors that facilitate daily gene expression rhythms differ between phylogenetic kingdoms. Human red blood cells (RBCs) exhibit temperature-compensated circadian rhythms, which, because RBCs lack nuclei, must occur in the absence of a circadian transcription-translation feedback loop. We tested whether period determination and temperature compensation are dependent on CKs in RBCs. As with nucleated cell types, broad-spectrum kinase inhibition with staurosporine lengthened the period of the RBC clock at 37°C, with more specific inhibition of CK1 and CK2 also eliciting robust changes in circadian period. Strikingly, inhibition of CK1 abolished temperature compensation and increased the Q10 for the period of oscillation in RBCs, similar to observations in nucleated cells. This indicates that CK1 activity is essential for circadian rhythms irrespective of the presence or absence of clock gene expression cycles.
Ruiz Da Silva Francieli, Beijamini Felipe, Beale Andrew, Goncalves Bruno da Silva B., Vartanian Daniel, Taporoski Tamara P., Middleton Benita, Krieger Jose E., Vallada Homero, Arendt Josephine, Pereira Alexandre C., Knutson Kristen L., Pedrazzoli Mario, von Schantz Malcolm (2020) Early chronotype with advanced activity rhythms and dim
light melatonin onset in a rural population, Journal of Pineal Research e12675
Studying communities at different stages of urbanisation and industrialisation can teach us how timing and intensity of light affects the circadian clock under real-life
conditions. We have previously described a strong tendency towards morningness in the Baependi Heart Study, located in a small rural town in Brazil. Here, we tested the
hypothesis that this morningness tendency is associated with early circadian phase based on objective measurements (as determined by dim light melatonin onset,
DLMO, and activity) and light exposure. We also analysed how well the previously collected chronotype questionnaire data was able to predict these DLMO values. The average DLMO observed in 73 participants (40 female) was 20:03±01:21, SD, with an earlier average onset in men (19:38±01:16) than in women (20:24±01:21; pd0.01). However, men presented larger phase angle between DLMO and sleep onset time as
measured by actigraphy (4.11 hours vs 3.16 hours; pd0.01). Correlational analysis indicated associations between light exposure, activity rhythms, and DLMO, such that
early DLMO was observed in participants with higher exposure to light, higher activity and earlier light exposure. The strongest significant predictor of DLMO was
morningness-eveningness questionnaire (MEQ) (beta=-0.35, pd0.05), followed by age(beta=-0.47, pd0.01). Sex, light exposure, and variables derived from the Munich
Chronotype Questionnaire were not significant predictors. Our observations demonstrate that both early sleep patterns and earlier circadian phase have been retained in this small rural town in spite of availability of electrification, in contrast to metropolitan post-industrial areas.