scholarly journals Rhizosphere microbes influence host circadian clock function

2018 ◽  
Author(s):  
Charley J. Hubbard ◽  
Robby McMinn ◽  
Cynthia Weinig
Keyword(s):  
Circadian Clock ◽  
Microbial Communities ◽  
Circadian Period ◽  
Wild Type ◽  
Host Genotype ◽  
Local Conditions ◽  
Mutant Genotype ◽  
Individual Fitness ◽  
Short Period ◽  
Clock Mutant

AbstractThe circadian clock is an important determinant of individual fitness that is entrained by local conditions. In addition to known abiotic inputs that entrain the circadian clock, individual pathogenic soil bacteria affect the circadian period of plant hosts. Yet, in nature, plants interact with diverse microbial communities including hundreds to thousands of microbial taxa, and the effect of these communities on clock function remains unclear. In Arabidopsis thaliana, we used diverse rhizosphere inoculates and both wild-type and clock mutant genotypes to test the effect of complex rhizosphere microbial communities on the host circadian clock. Host plants with an intact rhizosphere microbiome expressed a circadian period that was closer to 24 hrs in duration and significantly shorter (by 60 minutes on average) relative to plants grown with a disrupted microbiome. Wild-type host genotypes differed significantly in clock sensitivity to microbiome treatments, where the effect was most pronounced in the Landsberg erecta genotype and least in the Columbia genotype. Rhizosphere microbes collected from a host genotype with a short-period phenotype (toc1-21) and used as inoculate significantly shortened the long-period phenotype of the ztl-1 clock mutant genotype. The results indicate that complex rhizosphere microbial communities significantly affect host clock function.

scholarly journals Rhizosphere microbes influence host circadian clock function

2021 ◽  
Author(s):  
Charley Hubbard ◽  
Robby McMinn ◽  
Cynthia Weinig
Keyword(s):  
Arabidopsis Thaliana ◽  
Circadian Clock ◽  
Microbial Communities ◽  
Abiotic Factors ◽  
Circadian Period ◽  
Local Conditions ◽  
Mutant Genotype ◽  
Short Period ◽  
Clock Mutant ◽  
Boechera Stricta

The circadian clock is an important determinant of fitness that is entrained by local conditions. Aside from abiotic factors, individual pathogenic soil bacteria affect circadian clock function in plant hosts. Yet, in nature, plants interact with diverse microbial communities, and the effect of complex communities on clock function remains unclear. In Arabidopsis thaliana and its wild relative, Boechera stricta, we used diverse rhizosphere inoculates and host genotypes to test the effect of complex rhizosphere microbial communities on the host circadian clock. Arabidopsis thaliana plants with an intact rhizosphere microbiome expressed a circadian period closer to 24h in duration and significantly shorter (by 48 minutes on average) relative to plants grown with a disrupted microbiome. Wild-type host genotypes of A. thaliana differed in clock sensitivity to microbes, with one genotype (Landsberg erecta) expressing a 119-minute difference in circadian period length across rhizosphere microbial treatments. A similar pattern of clock sensitivity to soil microbes was observed in B. stricta. Finally, rhizosphere microbes collected from the mutant genotype toc1-21 of A. thaliana with a short-period phenotype and used as inoculate significantly shortened the long-period phenotype of the clock mutant genotype ztl-1. The results indicate that complex rhizosphere microbial communities affect host clock function.

scholarly journals ldpA Encodes an Iron-Sulfur Protein Involved in Light-Dependent Modulation of the Circadian Period in the Cyanobacterium Synechococcuselongatus PCC 7942

2003 ◽  
Vol 185 (4) ◽  
pp. 1415-1422 ◽  
Author(s):  
Mitsunori Katayama ◽  
Takao Kondo ◽  
Jin Xiong ◽  
Susan S. Golden
Keyword(s):  
Phase Shift ◽  
Circadian Clock ◽  
Binding Motif ◽  
Circadian Period ◽  
Wild Type ◽  
Reading Frame ◽  
Short Period ◽  
Screening Protocol ◽  
Dark Pulse ◽  
Pcc 7942

ABSTRACT We generated random transposon insertion mutants to identify genes involved in light input pathways to the circadian clock of the cyanobacterium Synechococcus elongatus PCC 7942. Two mutants, AMC408-M1 and AMC408-M2, were isolated that responded to a 5-h dark pulse differently from the wild-type strain. The two mutants carried independent transposon insertions in an open reading frame here named ldpA (for light-dependent period). Although the mutants were isolated by a phase shift screening protocol, the actual defect is a conditional alteration in the circadian period. The mutants retain the wild-type ability to phase shift the circadian gene expression (bioluminescent reporter) rhythm if the timing of administration of the dark pulse is corrected for a 1-h shortening of the circadian period in the mutant. Further analysis indicated that the conditional short-period mutant phenotype results from insensitivity to light gradients that normally modulate the circadian period in S. elongatus, lengthening the period at low light intensities. The ldpA gene encodes a polypeptide that predicts a 7Fe-8S cluster-binding motif expected to be involved in redox reactions. We suggest that the LdpA protein modulates the circadian clock as an indirect function of light intensity by sensing changes in cellular physiology.

scholarly journals GENETIC AND PHYSIOLOGICAL CHARACTERISTICS OF A SLOW-GROWING CIRCADIAN CLOCK MUTANT OF NEUROSPORA CRASSA

Genetics ◽  
1978 ◽  
Vol 88 (2) ◽  
pp. 255-265
Author(s):  
Jerry F Feldman ◽  
Cheryl A Atkinson
Keyword(s):  
Linkage Group ◽  
Circadian Clock ◽  
Neurospora Crassa ◽  
Double Mutant ◽  
Slow Growth ◽  
Period Length ◽  
The Other ◽  
Wild Type ◽  
Long Period ◽  
Clock Mutant

ABSTRACT A circadian clock mutant of Neurospora crassa with a period length of about 25.8 hours (4 hr longer than wild type) has been isolated after mutagenesis of the band strain. This mutant, called frq-5, segregates as a single nuclear gene, maps near the centromere on linkage group III, and is unlinked to four previously described clock mutants clustered on linkage group VII R (Feldman and Hoyle 1973, 1976). frq-5 differs from the other clock mutants in at least two other respects: (1) it is recessive in heterokaryons, and (2) it grows at about 60% the rate of the parent band strain on both minimal and complete media. Double mutants between frq-5 and each of the other clock mutants show additivity of period length-two long period mutants produce a double mutant whose period length is longer than either of the two single mutants, while a long and a short period double mutant has an intermediate period length. Although slow growth and long periodicity of frq-5 have segregated together among more than 300 progeny, slow growth per se is not responsible for the long period, since all the double mutants have the slow growth characteristic of frq-5, but have period lengths both shorter and longer than wild type.

Clockmutation facilitates accumulation of cholesterol in the liver of mice fed a cholesterol and/or cholic acid diet

2008 ◽  
Vol 294 (1) ◽  
pp. E120-E130 ◽  
Author(s):  
Takashi Kudo ◽  
Mihoko Kawashima ◽  
Toru Tamagawa ◽  
Shigenobu Shibata
Keyword(s):  
Gene Expression ◽  
Circadian Clock ◽  
Cholic Acid ◽  
Mouse Liver ◽  
Clock Genes ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Mutant Mice ◽  
Wild Type ◽  
Clock Mutant

Cholesterol (CH) homeostasis in the liver is regulated by enzymes of CH synthesis such as 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) and catabolic enzymes such as cytochrome P-450, family 7, subfamily A, and polypeptide 1 (CYP7A1). Since a circadian clock controls the gene expression of these enzymes, these genes exhibit circadian rhythm in the liver. In this study, we examined the relationship between a diet containing CH and/or cholic acid (CA) and the circadian regulation of Hmgcr, low-density lipoprotein receptor ( Ldlr), and Cyp7a1 gene expression in the mouse liver. A 4-wk CA diet lowered and eventually abolished the circadian expression of these genes. Not only clock genes such as period homolog 2 (Drosophila) ( Per2) and brain and muscle arnt-like protein-1 ( Bmal1) but also clock-controlled genes such as Hmgcr, Ldlr, and Cyp7a1 showed a reduced and arrhythmic expression pattern in the liver of Clock mutant mice. The reduced gene expression of Cyp7a1 in mice fed a diet containing CA or CH + CA was remarkable in the liver of Clock mutants compared with wild-type mice, and high liver CH accumulation was apparent in Clock mutant mice. In contrast, a CH diet without CA only elevated Cyp7a1 expression in both wild-type and Clock mutant mice. The present findings indicate that normal circadian clock function is important for the regulation of CH homeostasis in the mouse liver, especially in conjunction with a diet containing high CH and CA.

scholarly journals Natural selection against a circadian clock gene mutation in mice

2015 ◽  
Vol 113 (3) ◽  
pp. 686-691 ◽  
Author(s):  
Kamiel Spoelstra ◽  
Martin Wikelski ◽  
Serge Daan ◽  
Andrew S. I. Loudon ◽  
Michaela Hau
Keyword(s):  
Molecular Mechanisms ◽  
Internal Clock ◽  
Adult Survival ◽  
Wild Type ◽  
Strong Selection ◽  
Individual Fitness ◽  
Period 2 ◽  
Short Period ◽  
Feeding Rhythms ◽  
Tau Mutation

Circadian rhythms with an endogenous period close to or equal to the natural light–dark cycle are considered evolutionarily adaptive (“circadian resonance hypothesis”). Despite remarkable insight into the molecular mechanisms driving circadian cycles, this hypothesis has not been tested under natural conditions for any eukaryotic organism. We tested this hypothesis in mice bearing a short-period mutation in the enzyme casein kinase 1ε (tau mutation), which accelerates free-running circadian cycles. We compared daily activity (feeding) rhythms, survivorship, and reproduction in six replicate populations in outdoor experimental enclosures, established with wild-type, heterozygous, and homozygous mice in a Mendelian ratio. In the release cohort, survival was reduced in the homozygote mutant mice, revealing strong selection against short-period genotypes. Over the course of 14 mo, the relative frequency of the tau allele dropped from initial parity to 20%. Adult survival and recruitment of juveniles into the population contributed approximately equally to the selection for wild-type alleles. The expression of activity during daytime varied throughout the experiment and was significantly increased by the tau mutation. The strong selection against the short-period tau allele observed here contrasts with earlier studies showing absence of selection against a Period 2 (Per2) mutation, which disrupts internal clock function, but does not change period length. These findings are consistent with, and predicted by the theory that resonance of the circadian system plays an important role in individual fitness.

scholarly journals A RECESSIVE CIRCADIAN CLOCK MUTATION AT THE frq LOCUS OF NEUROSPORA CRASSA

Genetics ◽  
1986 ◽  
Vol 114 (4) ◽  
pp. 1095-1110
Author(s):  
Jennifer J Loros ◽  
Adam Richman ◽  
Jerry F Feldman
Keyword(s):  
Circadian Clock ◽  
Neurospora Crassa ◽  
Temperature Compensation ◽  
Single Gene ◽  
Complete Loss ◽  
The Other ◽  
Compensation Mechanism ◽  
Wild Type ◽  
Structure Mapping ◽  
Clock Mutant

ABSTRACT A circadian clock mutant of Neurospora crassa, the most distinctive characteristic of which is the complete loss of temperature compensation of its period length, maps to the frq locus where seven other clock mutants have previously been mapped. This mutant, designated frq-9, is recessive to the wild-type allele and to each of the other frq mutants; thus, it differs from the other mutants, which show incomplete dominance to wild type and to each other. Complementation analysis suggests either that the frq locus is a single gene or that frq-9 is a deletion that overlaps adjacent genes. Preliminary efforts at fine structure mapping have indicated that recombination between certain pairs of frq mutations is less than 0.005%, a distance consistent with the locus being a single gene. The recessive nature of frq-9, coupled with complete loss of temperature compensation, suggests that this mutant may represent the null phenotype of the locus and that the frq gene is involved in the temperature compensation mechanism of the clock.—Genetic mapping studies have placed the frq locus on linkage group VIIR, midway between oli (oligomycin resistance) and for (formate auxotrophy), about 2 map units from each, and clearly indicate that frq and oli are separate genes.

scholarly journals Changing planetary rotation rescues the biological clock mutantlhy cca1ofArabidopsis thaliana

2015 ◽  
Author(s):  
Andrew J. Millar ◽  
Jamie T. Carrington ◽  
Wei Ven Tee ◽  
Sarah K. Hodge
Keyword(s):  
Gene Expression ◽  
Circadian Clock ◽  
Double Mutant ◽  
Clock Genes ◽  
Biological Clock ◽  
Laboratory Model ◽  
Wild Type ◽  
Planetary Rotation ◽  
Short Period ◽  
Clock Mechanism

Background: Pervasive, 24-hour rhythms from the biological clock affect diverse biological processes in metabolism and behaviour, including the human cell division cycle and sleep-wake cycle, nightly transpiration and energy balance in plants, and seasonal breeding in both plants and animals. The clock mechanism in the laboratory model plant species Arabidopsis thaliana is complex, in part due to the multiple interlocking, negative feedback loops that link the clock genes. Clock gene mutants are powerful tools to manipulate and understand the clock mechanism and its effects on physiology. The LATE ELONGATED HYPOCOTYL and CIRCADIAN CLOCK ASSOCIATED 1 genes encode dawn-expressed, Myb-related repressor proteins that delay the expression of other clock genes until late in the day. Double mutant plants (lhy cca1) have low-amplitude, short-period rhythms that have been used in multiple studies of the plant circadian clock. Results: We used in vivo imaging of several luciferase (LUC) reporter genes to test how the rhythmic gene expression of wild-type and lhy cca1 mutant plants responded to light:dark cycles. Red, blue and red+blue light were similarly able to entrain these gene expression rhythms. The timing of expression rhythms in double mutant plants showed little or no response to the duration of light under 24h light:dark cycles (dusk sensitivity), in contrast to the wild type. As the period of the mutant clock is about 18h, we tested light:dark cycles of different duration (T cycles), simulating altered rotation of planet Earth. lhy cca1 double mutants regained as much dusk sensitivity in 20h T cycles as the wild type in 24h cycles, though the phase of the rhythm in the mutants was much earlier than wild type. The severe, triple lhy cca1 gi mutants also regained dusk sensitivity in 20h cycles. The double mutant showed some dusk sensitivity under 28h cycles. lhy cca1 double mutants under 28h cycles with short photoperiods, however, had the same apparent phase as wild-type plants. Conclusion: Simulating altered planetary rotation with light:dark cycles can reveal normal circadian performance in clock mutants that have been described as arrhythmic under standard conditions. The features rescued here comprise a dynamic behaviour (apparent phase under 28h cycles) and a dynamic property (dusk sensitivity under 20h cycles). These conditional clock phenotypes indicate that parts of the clock mechanism continue to function independently of LHY and CCA1, despite the major role of these genes in wild-type plants under standard conditions. Accessibility: Most results here will be published only in this format, citable by the DOI. Data and analysis are publicly accessible on the BioDare resource (www.biodare.ed.ac.uk), as detailed in the links below. Transgenic lines are linked to Stock Centre IDs below (Table 7).

scholarly journals Isolation and Characterization of a Temperature-Sensitive Circadian Clock Mutant of Neurospora crassa

Genetics ◽  
1997 ◽  
Vol 146 (2) ◽  
pp. 525-530 ◽  
Author(s):  
Louis W Morgan ◽  
Jerry F Feldman
Keyword(s):  
Circadian Clock ◽  
Neurospora Crassa ◽  
Mutant Strain ◽  
Double Mutant ◽  
Period Length ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Isolation And Characterization ◽  
Double Mutant Strain ◽  
Clock Mutant

A new circadian clock mutant has been isolated in Neurospora crassa. This new mutation, called period-6 (pd-6), has two features novel to known clock mutations. First, the mutation is temperature sensitive. At restrictive temperatures (above 21°) the mutation shortens circadian period length from a wild-type value of 21.5 hr to 18 hr. At permissive temperatures (below 21°) the mutant has a 20.5-hr period length close to that of the wild-type strain. Second, the prd-6 mutation is epistatic to the previously isolated clock mutation period-2 (prd-2). This epistasis is unusual in that the prd-2 prd-6 double mutant strain has an 18-hr period length at both the restrictive and permissive temperatures. That is, the temperature-sensitive aspect of the phenotype of the prd-6 strain is lost in the prd-2 prd-6 double mutant strain. This suggests that the gene products of the prd-2 and prd-6 loci may interact physically and that the presence of a normal prd-2+ protein is required for low temperature to “rescue” the prd-6 mutant phenotype. These results, combined with our recent finding that prd-2 and some alleles of the frq gene show genetic synergy, suggest that it may be possible to establish a more comprehensive model of the Neurospora circadian clock.

The short-period mutant, toc1-1, alters circadian clock regulation of multiple outputs throughout development in Arabidopsis thaliana

Development ◽  
1998 ◽  
Vol 125 (3) ◽  
pp. 485-494 ◽  
Author(s):  
D.E. Somers ◽  
A.A. Webb ◽  
M. Pearson ◽  
S.A. Kay
Keyword(s):  
Arabidopsis Thaliana ◽  
Circadian Clock ◽  
Red Light ◽  
Luciferase Reporter ◽  
Wild Type ◽  
Luciferase Reporter Gene ◽  
Environmental Signals ◽  
Developmental States ◽  
Short Period ◽  
Log Linear

The coordination of developmental and physiological events with environmental signals is facilitated by the action of the circadian clock. Here we report a new set of circadian clock-controlled phenotypes for Arabidopsis thaliana. We use these markers together with the short-period mutant, toc1-1, and the clock-controlled cab2::luciferase reporter gene to assess the nature of the circadian clock throughout development and to suggest the position of TOC1 within the circadian clock system. In dark-grown seedlings, the toc1-1 lesion conferred a short period to the cycling of cab2::luciferase luminescence, as previously found in light-grown plants, indicating that the circadian clocks in these two divergent developmental states share at least one component. Stomatal conductance rhythms were similarly approximately 3 hours shorter than wild type in toc1-1, suggesting that a cell-autonomous clockwork may be active in guard cells in 5- to 6-week-old leaves. The effect of daylength on flowering time in the C24 ecotype was diminished by toc1-1, and was nearly eliminated in the Landsberg erecta background where the plants flowered equally early in both short and long days. Throughout a 500-fold range of red light intensities, both the wild type and the mutant showed an inverse log-linear relationship of fluence rate to period, with a 2–3 hour shorter period for the mutant at all intensities. These results indicate that TOC1 acts on or within the clock independently of light input. Temperature entrainment appears normal in toc1-1, and the period-shortening effects of the mutant remain unchanged over a 20 degrees C temperature range. Taken together our results are consistent with the likelihood that TOC1 codes for an oscillator component rather than for an element of an input signaling pathway. In addition, the pervasive effect of toc1-1 on a variety of clock-controlled processes throughout development suggests that a single circadian system is primarily responsible for controlling most, if not all, circadian rhythms in the plant.

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