Defining the robust behaviour of the plant clock gene circuit with absolute RNA timeseries and open infrastructure.

Our understanding of the complex, transcriptional feedback loops in the circadian clock mechanism has depended upon quantitative, timeseries data from disparate sources. We measure clock gene RNA profiles in Arabidopsis thaliana seedlings, grown with or without exogenous sucrose, or in soil-grown plants and in wild-type and mutant backgrounds. The RNA profiles were strikingly robust across the experimental conditions, so current mathematical models are likely to be broadly applicable in leaf tissue.

ECERIFERUM2-LIKE proteins have unique biochemical and physiological functions in very-long-chain fatty acid elongation.

The extension of very-long-chain fatty acids (VLCFAs) for the synthesis of specialized apoplastic lipids requires unique biochemical machinery. Condensing enzymes catalyze the first reaction in fatty acid elongation and determine the chain length of fatty acids accepted and produced by the fatty acid elongation complex. Although necessary for the elongation of all VLCFAs, known condensing enzymes cannot efficiently synthesize VLCFAs longer than 28 carbons, despite the prevalence of C28 to C34 acyl lipids in cuticular wax and the pollen coat.

The mediator complex subunit PFT1 interferes with COP1 and HY5 in the regulation of Arabidopsis light signaling.

Arabidopsis (Arabidopsis thaliana) mutants hypersensitive to far-red light were isolated under a light program of alternating red and far-red light pulses and were named eid (for empfindlicher im dunkelroten Licht). The dominant eid3 mutant carries a missense mutation in a conserved domain of PHYTOCHROME AND FLOWERING TIME1 (PFT1), an important component of the plant mediator coactivator complex, which links promoter-bound transcriptional regulators to RNA polymerase II complexes. Epistatic analyses were performed to obtain information about the coaction between the mutated PFT1(eid3) and positively and negatively acting components of light signaling cascades.

The clock gene circuit in Arabidopsis includes a repressilator with additional feedback loops.

Circadian clocks synchronise biological processes with the day/night cycle, using molecular mechanisms that include interlocked, transcriptional feedback loops. Recent experiments identified the evening complex (EC) as a repressor that can be essential for gene expression rhythms in plants. Integrating the EC components in this role significantly alters our mechanistic, mathematical model of the clock gene circuit.

The plastid redox insensitive 2 mutant of Arabidopsis is impaired in PEP activity and high light-dependent plastid redox signalling to the nucleus.

The photosynthetic apparatus is composed of proteins encoded by genes from both the nuclear and the chloroplastic genomes. The activities of the nuclear and chloroplast genomes must therefore be closely coordinated through intracellular signalling. The plastids produce multiple retrograde signals at different times of their development, and in response to changes in the environment.

Stochastic properties of the plant circadian clock.

Circadian clocks are gene regulatory networks whose role is to help the organisms to cope with variations in environmental conditions such as the day/night cycle. In this work, we explored the effects of molecular noise in single cells on the behaviour of the circadian clock in the plant model species Arabidopsis thaliana. The computational modelling language Bio-PEPA enabled us to give a stochastic interpretation of an existing deterministic model of the clock, and to easily compare the results obtained via stochastic simulation and via numerical solution of the deterministic model.

The histidine kinase-related domain of Arabidopsis phytochrome a controls the spectral sensitivity and the subcellular distribution of the photoreceptor.

Phytochrome A (phyA) is the primary photoreceptor for sensing extremely low amounts of light and for mediating various far-red light-induced responses in higher plants. Translocation from the cytosol to the nucleus is an essential step in phyA signal transduction. EID1 (for EMPFINDLICHER IM DUNKELROTEN LICHT1) is an F-box protein that functions as a negative regulator in far-red light signaling downstream of the phyA in Arabidopsis (Arabidopsis thaliana).

Quantitative evaluation of perchlorethylene in groundwater before and after its oxidation by helical solid sorbent extraction and gas chromatography.

An integrated method of dynamic extraction of perchloroethylene (PCE) with polydimethylsiloxane (PDMS) helical solid sorbent followed by injection into a gas chromatograph was developed for the determination of the real concentration of PCE in groundwater before and after its degradation by oxidation with KMnO(4). The main parameters (agitation, temperature, salts, pH) that affect the extraction efficiency have been evaluated and optimized. The increase of the extracted amount of PCE due to the presence of the salts could be partially compensated by the opposite effect of the insoluble MnO(2), and of the presence of HCl and the global effect of the matrix would be less important for the reproducibility of the PCE extraction.

Retrograde signaling and plant stress: plastid signals initiate cellular stress responses.

Retrograde signaling coordinates the expression of nuclear genes encoding organellar proteins with the metabolic and developmental state of the organelle. These plastid signals are essential not only for coordinating photosynthetic gene expression in both the nucleus and in the chloroplasts but also for mediating plant stress responses. The chloroplasts therefore act as sensors of environmental changes and complex networks of plastid signals coordinate cellular activities and assist the cell during plant stress responses.

Thermally assisted mechanical dewatering (TAMD) of suspensions of fine particles: analysis of the influence of the operating conditions using the response surface methodology.

Thermally assisted mechanical dewatering (TAMD) is a new process for energy-efficient liquid/solids separation which enhances conventional-device efficiency. The main idea of this process is to supply a flow of heat in mechanical dewatering processes to favour the reduction of the liquid content. This is not a new idea but the proposed combination, especially the chosen operating conditions (temperature <100 degrees C and pressure <3000 kPa) constitutes an original approach and a significant energy saving since the liquid is kept in liquid state.

[Interventional catheterization after the Norwood procedure].

Introduction And Objectives: To carry out a retrospective analysis of the indications for, and the results and complications of interventional catheterization after the Norwood procedure.

Methods: Between February 1993 and December 2006, 25 interventional catheterizations were performed in 14 patients who had undergone the Norwood procedure, prior to the Glenn or Fontan procedure.

Results: Nine angioplasties were carried out for recoarctation in seven of the 14 patients (2 patients developed restenosis after their first angioplasty).

Analysis of the function of the photoreceptors phytochrome B and phytochrome D in Nicotiana plumbaginifolia and Arabidopsis thaliana.

To investigate the mechanism of phytochrome action in vivo, NtPHYB, AtPHYB and phyD:green fluorescent protein (GFP) were overexpressed in Nicotiana plumbaginifolia and Arabidopsis thaliana. The expression of 35S:NtPHYB:GFP and 35S:AtPHYB:GFP complemented the tobacco hgl2 and Arabidopsis phyB-9 mutations, whereas the 35S:AtPHYD:GFP only rescued the hgl2 mutant. All three fusion proteins are transported into the nucleus in all genetic backgrounds.

Characterization of regions in the GP5 protein of porcine reproductive and respiratory syndrome virus required to induce apoptotic cell death.

Expression of the GP5 protein of porcine reproductive and respiratory syndrome virus in mammalian cells using a recombinant vaccinia virus has been shown to induce strong cytotoxicity due to apoptotic death. We have now developed a transient expression system that allows the observation and quantitation of the cell death due to GP5 synthesis, taking advantage of the reduction that this protein induces in the expression of two different co-transfected reporter genes. In this way, we are able to study the regions in GP5 implicated in apoptosis induction.