Publications by authors named "Amanda M Davis"

Circadian clocks are endogenous timekeeping mechanisms that coordinate internal physiological responses with the external environment. EARLY FLOWERING3 (ELF3), PSEUDO RESPONSE REGULATOR (PRR9), and PRR7 are essential components of the plant circadian clock and facilitate entrainment of the clock to internal and external stimuli. Previous studies have highlighted a critical role for ELF3 in repressing the expression of PRR9 and PRR7.

View Article and Find Full Text PDF

Circadian rhythms coordinate endogenous events with external signals, and are essential to biological function. When environmental contaminants affect these rhythms, the organism may experience fitness consequences such as reduced growth or increased susceptibility to pathogens. In their natural environment plants may be exposed to a wide range of industrial and agricultural soil pollutants.

View Article and Find Full Text PDF

The plant circadian system reciprocally interacts with metabolic processes. To investigate entrainment features in metabolic-circadian interactions, we used a chemical approach to perturb metabolism and monitored the pace of nuclear-driven circadian oscillations. We found that chemicals that alter chloroplast-related functions modified the circadian rhythms.

View Article and Find Full Text PDF

Circadian rhythms allow an organism to synchronize internal physiological responses to the external environment. Perception of external signals such as light and temperature are critical in the entrainment of the oscillator. However, sugar can also act as an entraining signal.

View Article and Find Full Text PDF

The plant circadian clock allows the synchronization of internal physiological responses to match the predicted environment. HSP90.2 is a molecular chaperone that has been previously described as required for the proper functioning of the oscillator under both ambient and warm temperatures.

View Article and Find Full Text PDF

AKIN10, the catalytic subunit of the Snf1 (sucrose non-fermenting 1)-related kinase 1 (SnRK1) complex, acts as an energy sensor in plants. We showed that AKIN10-induced expression affects the pace of the circadian clock and particularly the phase of expression of GIGANTEA (GI). The AKIN10 effect on period length required TIME FOR COFFEE (TIC), a circadian-clock component with developmental and metabolic roles.

View Article and Find Full Text PDF

Circadian clocks have evolved independently in all three domains of life, suggesting that internal mechanisms of time-keeping are adaptive in contemporary populations. However, the performance consequences of either discrete or quantitative clock variation have rarely been tested in field settings. Clock sensitivity of diverse segregating lines to the environment remains uncharacterized as do the statistical genetic parameters that determine evolutionary potential.

View Article and Find Full Text PDF

Plants generate rhythmic metabolism during the repetitive day/night cycle. The circadian clock produces internal biological rhythms to synchronize numerous metabolic processes such that they occur at the required time of day. Metabolism conversely influences clock function by controlling circadian period and phase and the expression of core-clock genes.

View Article and Find Full Text PDF

A differential demand for copper (Cu) of essential cupro-proteins that act within the mitochondrial and chloroplastal electronic transport chains occurs along the daily light/dark cycles. This requires a fine-tuned spatiotemporal regulation of Cu delivery, becoming especially relevant under non-optimal growth conditions. When scarce, Cu is imported through plasma membrane-bound high affinity Cu transporters (COPTs) whose coding genes are transcriptionally induced by the SPL7 transcription factor.

View Article and Find Full Text PDF

Copper homeostasis under deficiency is regulated by the SQUAMOSA PROMOTER BINDING PROTEIN-LIKE7 (SPL7) transcription factor. The daily oscillating expression of two SPL7-dependent copper deficiency markers, COPPER TRANSPORTER (COPT2) and IRON SUPEROXIDE DISMUTASE (FSD1), has been followed by quantitative PCR and in promoter:LUCIFERASE transgenic plants. Both genes showed circadian and diurnal regulation.

View Article and Find Full Text PDF

Natural selection of variants within the Arabidopsis thaliana circadian clock can be attributed to adaptation to varying environments. To define a basis for such variation, we examined clock speed in a reporter-modified Bay-0 x Shakdara recombinant inbred line and localized heritable variation. Extensive variation led us to identify EARLY FLOWERING3 (ELF3) as a major quantitative trait locus (QTL).

View Article and Find Full Text PDF

Plants often respond to environmental changes by reprogramming metabolic and stress-associated pathways. Homeostatic integration of signaling is a central requirement for ensuring metabolic stability in living organisms. Under diurnal conditions, properly timed rhythmic metabolism provides fitness benefits to plants.

View Article and Find Full Text PDF

The constraint of a rotating earth has led to the evolution of a circadian clock that drives anticipation of future environmental changes. During this daily rotation, the circadian clock of Arabidopsis thaliana (Arabidopsis) intersects with the diurnal environment to orchestrate virtually all transcriptional processes of the plant cell, presumably by detecting, interpreting, and anticipating the environmental alternations of light and temperature. To comparatively assess differential inputs toward phenotypic and physiological responses on a circadian parameter, we surveyed clock periodicity in a recombinant inbred population modified to allow for robust periodicity measurements after entrainment to respective photic vs.

View Article and Find Full Text PDF

Generating and identifying transformants is essential for many studies of gene function. In Arabidopsis thaliana, a revolutionary protocol termed floral dip is now the most widely used transformation method. Although robust, it involves a number of relatively time-consuming and laborious steps, including manipulating an Agrobacterium tumefaciens culture and aseptic procedures for the selection of plant lines harboring antibiotic-selection markers.

View Article and Find Full Text PDF

Ischemic preconditioning renders the heart resistant to infarction from ischemia/reperfusion. Over the past two decades a great deal has been learned about preconditioning's mechanism. Adenosine, bradykinin, and opioids act in parallel to trigger the preconditioned state and do so by activating PKC.

View Article and Find Full Text PDF

The plant circadian clock is required for daily anticipation of the diurnal environment. Mutation in Arabidopsis thaliana TIME FOR COFFEE (TIC) affects free-running circadian rhythms. To investigate how TIC functions within the circadian system, we introduced markers for the evening and morning phases of the clock into tic and measured evident rhythms.

View Article and Find Full Text PDF

Objective: Ischemic postconditioning protects the reperfused heart from infarction, and this protection is dependent on the occupancy of adenosine receptors. We further explored the role of adenosine receptors in this salvage.

Methods: In situ rabbit hearts underwent 30 min of regional ischemia and 3 h of reperfusion, and postconditioning was effected with four cycles of 30-s reperfusion/30-s coronary artery occlusion at the end of ischemia.

View Article and Find Full Text PDF