PSEUDO-RESPONSE REGULATOR 7 and 9 are partially redundant genes essential for the temperature responsiveness of the Arabidopsis circadian clock.

Dartmouth College, Department of Biological Sciences, Hanover, New Hampshire 03755-3576, USA.
The Plant Cell (Impact Factor: 9.25). 04/2005; 17(3):791-803. DOI: 10.1105/tpc.104.029504
Source: PubMed

ABSTRACT Environmental time cues, such as photocycles (light/dark) and thermocycles (warm/cold), synchronize (entrain) endogenous biological clocks to local time. Although much is known about entrainment of the Arabidopsis thaliana clock to photocycles, the determinants of thermoperception and entrainment to thermocycles are not known. The Arabidopsis PSEUDO-RESPONSE REGULATOR (PRR) genes, including the clock component TIMING OF CAB EXPRESSION 1/PRR1, are related to bacterial, fungal, and plant response regulators but lack the conserved Asp that is normally phosphorylated by an upstream sensory kinase. Here, we show that two PRR family members, PRR7 and PRR9, are partially redundant; single prr7-3 or prr9-1 mutants exhibit modest period lengthening, but the prr7-3 prr9-1 double mutant shows dramatic and more than additive period lengthening in the light and becomes arrhythmic in constant darkness. The prr7-3 prr9-1 mutant fails both to maintain an oscillation after entrainment to thermocycles and to reset its clock in response to cold pulses and thus represents an important mutant strongly affected in temperature entrainment in higher plants. We conclude that PRR7 and PRR9 are critical components of a temperature-sensitive circadian system. PRR7 and PRR9 could function in temperature and light input pathways or they could represent elements of an oscillator necessary for the clock to respond to temperature signals.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Moderately warm constant ambient temperatures tend to oppose light signals in the control of plant architecture. By contrast, here we show that brief heat shocks enhance the inhibition of hypocotyl growth induced by light perceived by phytochrome B in deetiolating Arabidopsis thaliana seedlings. In darkness, daily heat shocks transiently increased the expression of PSEUDO-RESPONSE REGULATOR7 (PRR7) and PRR9 and markedly enhanced the amplitude of the rhythms of LATE ELONGATED HYPOCOTYL (LHY) and CIRCADIAN CLOCK ASSOCIATED1 (CCA1) expression. In turn, these rhythms gated the hypocotyl response to red light, in part by changing the expression of PHYTOCHROME INTERACTING FACTOR4 (PIF4) and PIF5. After light exposure, heat shocks also reduced the nuclear abundance of CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1) and increased the abundance of its target ELONGATED HYPOCOTYL5 (HY5). The synergism between light and heat shocks was deficient in the prr7 prr9, lhy cca1, pif4 pif5, cop1, and hy5 mutants. The evening element (binding site of LHY and CCA1) and G-box promoter motifs (binding site of PIFs and HY5) were overrepresented among genes with expression controlled by both heat shock and red light. The heat shocks experienced by buried seedlings approaching the surface of the soil prepare the seedlings for the impending exposure to light by rhythmically lowering LHY, CCA1, PIF4, and PIF5 expression and by enhancing HY5 stability.
    The Plant Cell 08/2013; · 9.25 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Proefschrift--Amsterdam.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Blue crabs Callinectes sapidus, like most decapods, synchronously hatch eggs and release larvae over a very short time period. Synchrony is achieved though vigorous abdominal pumping in response to pheromones from hatching eggs. We hypothesized that these or related pheromones stimulate vertical swimming associated with larval release and ebb-tide swimming during the last few days before egg hatching. We used abdominal pumping and swimming assays to investigate the roles of pheromones. We tested responses of crabs to egg extract containing pheromones, trypsin (an enzyme that generates peptide pheromones), and bradykinin (a peptide pheromone mimic). We delivered test substances directly into the egg mass via capillary tubing. In response to egg extract, ovigerous crabs increased abdominal pumping and vertical swimming, showing native pheromones evoke both behaviors. Delivery of trypsin and bradykinin caused increased pumping but not vertical swimming. These results suggest that pheromones generated from eggs stimulate vertical swimming during ebb-tide transport, but that peptides that induce abdominal pumping are not sufficient to cause swimming. We hypothesize that swimming is stimulated by a blend of molecules that includes these peptide pheromones.
    Journal of Experimental Marine Biology and Ecology 08/2010; 391(1-2):112-117. · 2.26 Impact Factor


Available from