scholarly journals Transcriptional Structure of Petunia Clock in Leaves and Petals

Genes ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 860 ◽  
Author(s):  
Marta I. Terry ◽  
Marta Carrera-Alesina ◽  
Julia Weiss ◽  
Marcos Egea-Cortines
Keyword(s):  
Circadian Clock ◽  
Clock Genes ◽  
Time Of Day ◽  
Constant Darkness ◽  
Petunia X Hybrida ◽  
Environmental Signals ◽  
Expression Variability ◽  
Rhythmic Expression ◽  
Free Running ◽  
Maximum Expression

The plant circadian clock coordinates environmental signals with internal processes including secondary metabolism, growth, flowering, and volatile emission. Plant tissues are specialized in different functions, and petals conceal the sexual organs while attracting pollinators. Here we analyzed the transcriptional structure of the petunia (Petunia x hybrida) circadian clock in leaves and petals. We recorded the expression of 13 clock genes in petunia under light:dark (LD) and constant darkness (DD). Under light:dark conditions, clock genes reached maximum expression during the light phase in leaves and the dark period in petals. Under free running conditions of constant darkness, maximum expression was delayed, especially in petals. Interestingly, the rhythmic expression pattern of PhLHY persisted in leaves and petals in LD and DD. Gene expression variability differed among leaves and petals, time of day and photoperiod. The transcriptional noise was higher especially in leaves under constant darkness. We found that PhPRR7, PhPRR5, and PhGI paralogs showed changes in gene structure including exon number and deletions of CCT domain of the PRR family. Our results revealed that petunia petals presented a specialized clock.

scholarly journals The role of clockwork orange in the circadian clock of the cricket Gryllus bimaculatus

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Yasuaki Tomiyama ◽  
Tsugumichi Shinohara ◽  
Mirai Matsuka ◽  
Tetsuya Bando ◽  
Taro Mito ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Clock Genes ◽  
Clock Cycle ◽  
Constant Darkness ◽  
Mrna Levels ◽  
Gryllus Bimaculatus ◽  
Locomotor Rhythm ◽  
Rhythmic Expression ◽  
Cryptochrome 2

Abstract The circadian clock generates rhythms of approximately 24 h through periodic expression of the clock genes. In insects, the major clock genes period (per) and timeless (tim) are rhythmically expressed upon their transactivation by CLOCK/CYCLE, with peak levels in the early night. In Drosophila, clockwork orange (cwo) is known to inhibit the transcription of per and tim during the daytime to enhance the amplitude of the rhythm, but its function in other insects is largely unknown. In this study, we investigated the role of cwo in the clock mechanism of the cricket Gryllus bimaculatus. The results of quantitative RT-PCR showed that under a light/dark (LD) cycle, cwo is rhythmically expressed in the optic lobe (lamina-medulla complex) and peaks during the night. When cwo was knocked down via RNA interference (RNAi), some crickets lost their locomotor rhythm, while others maintained a rhythm but exhibited a longer free-running period under constant darkness (DD). In cwoRNAi crickets, all clock genes except for cryptochrome 2 (cry2) showed arrhythmic expression under DD; under LD, some of the clock genes showed higher mRNA levels, and tim showed rhythmic expression with a delayed phase. Based on these results, we propose that cwo plays an important role in the cricket circadian clock.

The intrinsic circadian clock within the cardiomyocyte

2005 ◽  
Vol 289 (4) ◽  
pp. H1530-H1541 ◽  
Author(s):  
David J. Durgan ◽  
Margaret A. Hotze ◽  
Tara M. Tomlin ◽  
Oluwaseun Egbejimi ◽  
Christophe Graveleau ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Molecular Mechanisms ◽  
Clock Genes ◽  
Time Of Day ◽  
Pyruvate Dehydrogenase Kinase ◽  
Continuous Treatment ◽  
Rat Cardiomyocytes ◽  
Rhythmic Expression ◽  
Adult Rat ◽  
Circadian Clock Genes

Circadian clocks are intracellular molecular mechanisms that allow the cell to anticipate the time of day. We have previously reported that the intact rat heart expresses the major components of the circadian clock, of which its rhythmic expression in vivo is consistent with the operation of a fully functional clock mechanism. The present study exposes oscillations of circadian clock genes [brain and arylhydrocarbon receptor nuclear translocator-like protein 1 ( bmal1), reverse strand of the c-erbaα gene ( rev-erbaα), period 2 ( per2), albumin D-element binding protein ( dbp)] for isolated adult rat cardiomyocytes in culture. Acute (2 h) and/or chronic (continuous) treatment of cardiomyocytes with FCS (50% and 2.5%, respectively) results in rhythmic expression of circadian clock genes with periodicities of 20–24 h. In contrast, cardiomyocytes cultured in the absence of serum exhibit dramatically dampened oscillations in bmal1 and dbp only. Zeitgebers (timekeepers) are factors that influence the timing of the circadian clock. Glucose, which has been previously shown to reactivate circadian clock gene oscillations in fibroblasts, has no effect on the expression of circadian clock genes in adult rat cardiomyocytes, either in the absence or presence of serum. Exposure of adult rat cardiomyocytes to the sympathetic neurotransmitter norephinephrine (10 μM) for 2 h reinitiates rhythmic expression of circadian clock genes in a serum-independent manner. Oscillations in circadian clock genes were associated with 24-h oscillations in the metabolic genes pyruvate dehydrogenase kinase 4 ( pdk4) and uncoupling protein 3 ( ucp3). In conclusion, these data suggest that the circadian clock operates within the myocytes of the heart and that this molecular mechanism persists under standard cell culture conditions (i.e., 2.5% serum). Furthermore, our data suggest that norepinephrine, unlike glucose, influences the timing of the circadian clock within the heart and that the circadian clock may be a novel mechanism regulating myocardial metabolism.

Achilles-Mediated and Sex-Specific Regulation of Circadian mRNA Rhythms in Drosophila

2019 ◽  
Vol 34 (2) ◽  
pp. 131-143 ◽  
Author(s):  
Jiajia Li ◽  
Renee Yin Yu ◽  
Farida Emran ◽  
Brian E. Chen ◽  
Michael E. Hughes
Keyword(s):  
Circadian Clock ◽  
Molecular Mechanisms ◽  
Rna Binding ◽  
Clock Genes ◽  
Peripheral Tissues ◽  
Knock Down ◽  
Rhythmic Expression ◽  
The Core ◽  
Physiological Processes ◽  
Specific Regulation

The circadian clock is an evolutionarily conserved mechanism that generates the rhythmic expression of downstream genes. The core circadian clock drives the expression of clock-controlled genes, which in turn play critical roles in carrying out many rhythmic physiological processes. Nevertheless, the molecular mechanisms by which clock output genes orchestrate rhythmic signals from the brain to peripheral tissues are largely unknown. Here we explored the role of one rhythmic gene, Achilles, in regulating the rhythmic transcriptome in the fly head. Achilles is a clock-controlled gene in Drosophila that encodes a putative RNA-binding protein. Achilles expression is found in neurons throughout the fly brain using fluorescence in situ hybridization (FISH), and legacy data suggest it is not expressed in core clock neurons. Together, these observations argue against a role for Achilles in regulating the core clock. To assess its impact on circadian mRNA rhythms, we performed RNA sequencing (RNAseq) to compare the rhythmic transcriptomes of control flies and those with diminished Achilles expression in all neurons. Consistent with previous studies, we observe dramatic upregulation of immune response genes upon knock-down of Achilles. Furthermore, many circadian mRNAs lose their rhythmicity in Achilles knock-down flies, suggesting that a subset of the rhythmic transcriptome is regulated either directly or indirectly by Achilles. These Achilles-mediated rhythms are observed in genes involved in immune function and in neuronal signaling, including Prosap, Nemy and Jhl-21. A comparison of RNAseq data from control flies reveals that only 42.7% of clock-controlled genes in the fly brain are rhythmic in both males and females. As mRNA rhythms of core clock genes are largely invariant between the sexes, this observation suggests that sex-specific mechanisms are an important, and heretofore under-appreciated, regulator of the rhythmic transcriptome.

scholarly journals Free-running circadian breathing rhythms are eliminated by suprachiasmatic nucleus lesion

2020 ◽  
Vol 129 (1) ◽  
pp. 49-57
Author(s):  
Benton S. Purnell ◽  
Gordon F. Buchanan
Keyword(s):  
Sleep Apnea ◽  
Circadian Rhythms ◽  
Suprachiasmatic Nucleus ◽  
Time Of Day ◽  
Sudden Unexpected Death ◽  
Constant Darkness ◽  
Unexpected Death ◽  
Treatment And Prevention ◽  
Free Running

It has long been appreciated that breathing is altered by time of day. This study demonstrates that rhythmicity in breathing persists in constant darkness but is dependent on the suprachiasmatic nucleus in the hypothalamus. Understanding circadian rhythms in breathing may be important for the treatment and prevention of diseases such as sleep apnea and sudden unexpected death in epilepsy.

scholarly journals Rhythmic expression of circadian clock genes in the preovulatory ovarian follicles of the laying hen

PLoS ONE ◽  
2017 ◽  
Vol 12 (6) ◽  
pp. e0179019 ◽  
Author(s):  
Zhichao Zhang ◽  
Shuang Lai ◽  
Yagang Wang ◽  
Liang Li ◽  
Huadong Yin ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Clock Genes ◽  
Ovarian Follicles ◽  
Laying Hen ◽  
Rhythmic Expression ◽  
Circadian Clock Genes

Modulatory effects of 5-fluorouracil on the rhythmic expression of circadian clock genes: A possible mechanism of chemotherapy-induced circadian rhythm disturbances

2008 ◽  
Vol 75 (8) ◽  
pp. 1616-1622 ◽  
Author(s):  
Hideyuki Terazono ◽  
Ahmed Hamdan ◽  
Naoya Matsunaga ◽  
Naoto Hayasaka ◽  
Hiroaki Kaji ◽  
...  
Keyword(s):  
Circadian Rhythm ◽  
Circadian Clock ◽  
Clock Genes ◽  
Rhythmic Expression ◽  
Circadian Clock Genes

scholarly journals Deep sequencing analysis of the circadian transcriptome of the jewel wasp Nasonia vitripennis

2016 ◽  
Author(s):  
Nathaniel J. Davies ◽  
Eran Tauber
Keyword(s):  
Circadian Clock ◽  
Deep Sequencing ◽  
Clock Genes ◽  
Model System ◽  
Model Organisms ◽  
Constant Darkness ◽  
Sequencing Analysis ◽  
Rna Seq ◽  
Nasonia Vitripennis ◽  
Deep Sequencing Analysis

AbstractThe study of the circadian clock has benefited greatly from using Drosophila as a model system. Yet, accumulating evidence suggests that the fly might not be the canonical insect model. Here, we have analysed the circadian transcriptome of the Jewl wasp Nasonia vitripennis by using RNA-seq in both constant darkness (DD) and constant light (LL, the wasps are rhythmic in LL with period shortening). At a relatively stringent FDR (q < 0.1), we identified 1,057 cycling transcripts in DD and 929 in LL (fraction of 6.7% and 5.9% of all transcripts analysed in DD and LL respectively). Although there was little similarity between cycling genes in Drosophila and Nasonia, the functions fulfilled by cycling transcripts were similar in both species. Of the known Drosophila core clock genes, only pdp1e, shaggy and Clok showed a significant cycling in Nasonia, underscoring the importance of studying the clock in non-model organisms.

scholarly journals The Circadian Clock Is Sustained in the Thyroid Gland of VIP Receptor 2 Deficient Mice

2021 ◽  
Vol 12 ◽  
Author(s):  
Birgitte Georg ◽  
Jan Fahrenkrug ◽  
Henrik L. Jørgensen ◽  
Jens Hannibal
Keyword(s):  
Circadian Clock ◽  
Clock Genes ◽  
Hormone Secretion ◽  
Heart Rhythm ◽  
Thyroid Stimulating Hormone ◽  
Constant Darkness ◽  
Receptor Signaling ◽  
Knockout Animals ◽  
The Impact ◽  
Deficient Mice

VIP/VPAC2-receptor signaling is crucial for functioning of the circadian clock in the suprachiasmatic nucleus (SCN) since the lack results in disrupted synchrony between SCN cells and altered locomotor activity, body temperature, hormone secretion and heart rhythm. Endocrine glands, including the thyroid, show daily oscillations in clock gene expression and hormone secretion, and SCN projections target neurosecretory hypothalamic thyroid-stimulating hormone (TSH)-releasing hormone cells. The aim of the study was to gain knowledge of mechanisms important for regulation of the thyroid clock by evaluating the impact of VIP/VPAC2-receptor signaling. Quantifications of mRNAs of three clock genes (Per1, Per2 and Bmal1) in thyroids of wild type (WT) and VPAC2-receptor deficient mice were done by qPCR. Tissues were taken every 4th h during 24-h 12:12 light-dark (LD) and constant darkness (DD) periods, both genders were used. PER1 immunoreactivity was visualized on sections of both WT and VPAC2 lacking mice during a LD cycle. Finally, TSH and the thyroid hormone T4 levels were measured in the sera by commercial ELISAs. During LD, rhythmic expression of all three mRNA was found in both the WT and knockout animals. In VPAC2-receptor knockout animals, the amplitudes were approximately halved compared to the ones in the WT mice. In the WT, Per1 mRNA peaked around “sunset”, Per2 mRNA followed with approximately 2 h, while Bmal1 mRNA was in antiphase with Per1. In the VPAC2 knockout mice, the phases of the mRNAs were advanced approximately 5 h compared to the WT. During DD, the phases of all the mRNAs were identical to the ones found during LD in both groups of mice. PER1 immunoreactivity was delayed compared to its mRNA and peaked during the night in follicular cells of both the thyroid and parathyroid glands in the WT animals. In WT animals, TSH was high around the transition to darkness compared to light-on, while T4 did not change during the 24 h cycle. In conclusion, sustained and identical rhythms (phases and amplitudes) of three clock genes were found in VPAC2 deficient mice during LD and DD suggesting high degree of independence of the thyroid clock from the master SCN clock.

scholarly journals Period 2: A Regulator of Multiple Tissue-Specific Circadian Functions

2021 ◽  
Vol 14 ◽  
Author(s):  
Gennaro Ruggiero ◽  
Zohar Ben-Moshe Livne ◽  
Yair Wexler ◽  
Nathalie Geyer ◽  
Daniela Vallone ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Clock Genes ◽  
Central Element ◽  
Light Sensitivity ◽  
Loss Of Function ◽  
Tissue Specific ◽  
Rhythmic Expression ◽  
Period 2 ◽  
Circadian Clock Genes

The zebrafish represents a powerful model for exploring how light regulates the circadian clock due to the direct light sensitivity of its peripheral clocks, a property that is retained even in organ cultures as well as zebrafish-derived cell lines. Light-inducible expression of the per2 clock gene has been predicted to play a vital function in relaying light information to the core circadian clock mechanism in many organisms, including zebrafish. To directly test the contribution of per2 to circadian clock function in zebrafish, we have generated a loss-of-function per2 gene mutation. Our results reveal a tissue-specific role for the per2 gene in maintaining rhythmic expression of circadian clock genes, as well as clock-controlled genes, and an impact on the rhythmic behavior of intact zebrafish larvae. Furthermore, we demonstrate that disruption of the per2 gene impacts on the circadian regulation of the cell cycle in vivo. Based on these results, we hypothesize that in addition to serving as a central element of the light input pathway to the circadian clock, per2 acts as circadian regulator of tissue-specific physiological functions in zebrafish.

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