Dynamic, auxin-responsive plasma membrane-to-nucleus movement of Arabidopsis BRX.

In Arabidopsis, interplay between nuclear auxin perception and trans-cellular polar auxin transport determines the transcriptional auxin response. In brevis radix (brx) mutants, this response is impaired, probably indirectly because of disturbed crosstalk between the auxin and brassinosteroid pathways. Here we provide evidence that BRX protein is plasma membrane-associated, but translocates to the nucleus upon auxin treatment to modulate cellular growth, possibly in conjunction with NGATHA class B3 domain-type transcription factors. Application of the polar auxin transport inhibitor naphthalene phthalamic acid (NPA) resulted in increased BRX abundance at the plasma membrane. Thus, nuclear translocation of BRX could depend on cellular auxin concentration or on auxin flux. Supporting this idea, NPA treatment of wild-type roots phenocopied the brx root meristem phenotype. Moreover, BRX is constitutively turned over by the proteasome pathway in the nucleus. However, a stabilized C-terminal BRX fragment significantly rescued the brx root growth phenotype and triggered a hypocotyl gain-of-function phenotype, similar to strong overexpressors of full length BRX. Therefore, although BRX activity is required in the nucleus, excess activity interferes with normal development. Finally, similar to the PIN-FORMED 1 (PIN1) auxin efflux carrier, BRX is polarly localized in vascular cells and subject to endocytic recycling. Expression of BRX under control of the PIN1 promoter fully rescued the brx short root phenotype, suggesting that the two genes act in the same tissues. Collectively, our results suggest that BRX might provide a contextual readout to synchronize cellular growth with the auxin concentration gradient across the root tip.

Genetic removal of tri-unsaturated fatty acids suppresses developmental and molecular phenotypes of an Arabidopsis tocopherol-deficient mutant. Whole-body mapping of malondialdehyde pools in a complex eukaryote.

Malondialdehyde (MDA) is a small, ubiquitous, and potentially toxic aldehyde that is produced in vivo by lipid oxidation and that is able to affect gene expression. Tocopherol deficiency in the vitamin E2 mutant vte2-1 of Arabidopsis thaliana leads to massive lipid oxidation and MDA accumulation shortly after germination. MDA accumulation correlates with a strong visual phenotype (growth reduction, cotyledon bleaching) and aberrant GST1 (glutathione S-transferase 1) expression. We suppressed MDA accumulation in the vte2-1 background by genetically removing tri-unsaturated fatty acids. The resulting quadruple mutant, fad3-2 fad7-2 fad8 vte2-1, did not display the visual phenotype or the aberrant GST1 expression observed in vte2-1. Moreover, cotyledon bleaching in vte2-1 was chemically phenocopied by treatment of wild-type plants with MDA. These data suggest that products of tri-unsaturated fatty acid oxidation underlie the vte2-1 seedling phenotype, including cellular toxicity and gene regulation properties. Generation of the quadruple mutant facilitated the development of an in situ fluorescence assay based on the formation of adducts of MDA with 2-thiobarbituric acid at 37 degrees C. Specificity was verified by measuring pentafluorophenylhydrazine derivatives of MDA and by liquid chromatography analysis of MDA-2-thiobarbituric acid adducts. Potentially applicable to other organisms, this method allowed the localization of MDA pools throughout the body of Arabidopsis and revealed an undiscovered pool of the compound unlikely to be derived from trienoic fatty acids in the vicinity of the root tip quiescent center.

Microfabricated dual sprayer for on-line mass tagging of phosphopeptides.

Phosphopeptides tagging reactions by dinuclear zinc(II) complexes (1,3-bis[bis(2-pyridylmethyl)amino]-propan-2-olato dizinc(II)3+, called tag) were performed with a dual-channel microsprayer in electrospray ionization mass spectrometry. The reaction is first studied ex situ and analyzed with a commercial electrospray source. In situ reactions (i.e., inside the Taylor cone) were achieved with a dual-channel microsprayer both with the tag synthesized chemically before the experiments and with the tag electrogenerated by in situ oxidation of a zinc electrode, also used to apply the electrospray current. The device consists of a polyimide microchip with two microchannels (20 microm x 50 microm x 1 cm) etched on each side of the structure and connecting only at the tip of the microchip. We demonstrate here that mixing two solutions with different physicochemical properties inside the Taylor cone can be used to selectively tag target molecules.

Simultaneous determination of Pu and Am radioisotopes in environmental samples: a tool for determining origin and release date

A radiochemical procedure was developed for the sequential determination of Pu and Am radioisotopes in environmental samples. The radioisotope activities were then used to assess the origin and release date of the environmental plutonium. The radioanalytical procedure is based on the separation of Pu and Am on selective extraction chromatographic resins (Eichrom TEVA and DGA). Alpha sources were prepared by electrodeposition on stainless steel discs, and the alpha emitting radionuclides (238Pu, 239,240Pu and 241Am) were measured by alpha spectrometry. For the determination of the beta emitting 241Pu, the Pu alpha source was leached in hot concentrated nitric acid and the Pu fraction further purified by extraction chromatography on a small column of TEVA resin (100 μg of resin in a pipette tip). 241Pu is then measured by ultra low level liquid scintillation counting. Due to the lack of reference material for 241Pu, the proposed radiochemical method was nevertheless validated using four IAEA reference sediments with information values of 241Pu. The proposed method was then used to determine the 238Pu, 239,240Pu, 241Pu and 241Am activity concentrations in alpine soils of France and Switzerland. The soil is the primary receptor of the atmospheric radioactive fallout and, because of the strong binding interaction with soils particles, the isotopes are little fractionated. Therefore, the activity ratios 241Pu/239+240Pu and 238Pu/239,240Pu in soil samples were used to determine the origin (source) and date of the Pu contamination in the investigated alpine sites. The 241Pu/239,240Pu and 238Pu/239,240Pu activity ratios confirmed that the main origin of Pu in the alpine soils was the global fallout from the nuclear bomb tests (NBT) in the fifties and sixties. Furthermore, the 241Pu/241Am activity ratios were used to determine the age of the Pu contamination, which is also an important data for distinguishing the Pu sources. The estimation of the date of the contamination, by the 241Pu/241Am age-dating method, further confirmed the NBT as the Pu source. However, the 241Pu/241Am dating method was limited to samples where Pu-Am fractionation was insignificant. If any, the contribution of the Chernobyl accident in the studied sites is negligible.

Renal tumor ablation using radiofrequency: results in 28 patient. Exposition scientifique: Radiologie interventionnelle

Objectifs: To describe the technique and results of radiofrequency ablation (RFA) of small renal tumors.Matériels et méthodes: 28 patients with median age 79 years were treated with RFA for small renal exophytic tumor (median size 20 mm). Most patients were poor operative candidatesbecause of associated morbidity. Four patients were treated for biopsy proven papillary tumor, 7 for clear cell carcinoma, 2 for oncocytoma and one for renalhepatocellular metastasis. No biopsy sample was obtained for the others because of a typical radiological aspect of RCC.Résultats: All patients but one were treated successfully in one session under combined ultrasound and CT guidance using either Radionics 2000 cool-tip or Bostonscientific expandable needles, one was treated in two sessions. One Splenic, 3 colic and 1 pancreatic displacement with CO2 injection and one injection of G5%solution in the costo-phrenic recessus were done in order to protect adjacent organs. Two complications were observed, one splenic iatrogenic lesion treated byembolization and one renal pelvis stenosis treated with JJ stent. After a mean follow-up of 20 months, no patient developped local recurrence on MRI follow-up.Conclusion: RFA is a simple and efficient technique pending on strict selected criteria (small size < 3 cm and exophytic lesion). Long local control is obtained with minimalmorbidity.

Nurture versus nature: long-term impact of forced right-handedness on structure of pericentral cortex and basal ganglia.

Does a conflict between inborn motor preferences and educational standards during childhood impact the structure of the adult human brain? To examine this issue, we acquired high-resolution T1-weighted magnetic resonance scans of the whole brain in adult "converted" left-handers who had been forced as children to become dextral writers. Analysis of sulcal surfaces revealed that consistent right- and left-handers showed an interhemispheric asymmetry in the surface area of the central sulcus with a greater surface contralateral to the dominant hand. This pattern was reversed in the converted group who showed a larger surface of the central sulcus in their left, nondominant hemisphere, indicating plasticity of the primary sensorimotor cortex caused by forced use of the nondominant hand. Voxel-based morphometry showed a reduction of gray matter volume in the middle part of the left putamen in converted left-handers relative to both consistently handed groups. A similar trend was found in the right putamen. Converted subjects with at least one left-handed first-degree relative showed a correlation between the acquired right-hand advantage for writing and the structural changes in putamen and pericentral cortex. Our results show that a specific environmental challenge during childhood can shape the macroscopic structure of the human basal ganglia. The smaller than normal putaminal volume differs markedly from previously reported enlargement of cortical gray matter associated with skill acquisition. This indicates a differential response of the basal ganglia to early environmental challenges, possibly related to processes of pruning during motor development.

Supraclavicular flap in head and neck reconstruction: experience in 50 consecutive patients.

The supraclavicular flap (SCF) is a fasciocutaneous flap used to cover head, oral, and neck region defects after tumor resection. Its main vascular supply is the supraclavicular artery and accompanying veins and it can be harvested as a vascularised pedicled flap. The SCF serves as an excellent outer skin cover as well as a good inner mucosal lining after oral cavity and head-neck tumor resections. The flap has a wide arc of rotation and matches the skin colour and texture of the face and neck. Between March 2006 and March 2011, the pedicled supraclavicular flap was used for reconstruction in 50 consecutive patients after head and neck tumor resections and certain benign conditions in a tertiary university hospital setting. The flaps were tunnelized under the neck skin to cover the external cervicofacial defects or passed medial to the mandible to give an inner epithelial lining after the oral cavity and oropharyngeal tumor excision. Forty-four of the 50 patients had 100% flap survival with excellent wound healing. All the flaps were harvested in less than 1 h. There were four cases of distal tip desquamation and two patients had complete flap necrosis. Distal flap desquamation was observed in SCFs used for resurfacing the external skin defects after oral cavity tumor ablation and needed only conservative treatment measures. Total flap failure was encountered in two patients who had failed in previous chemoradiotherapy for squamous cell cancer of the floor of mouth and tonsil, respectively, and the SCF was used in mucosal defect closure after tumor ablation. The benefits of a pedicled fasciocutaneous supraclavicular flap are clear; it is thin, reliable, easy, and quick to harvest. In head, face and neck reconstructions, it is a good alternative to free fasciocutaneous flaps, regional pedicled myocutaneous flaps, and the deltopectoral flap.

Velocity fluctuations of fracturelike disruptions of associating polymer solutions

Velocity has been measured as a function of time for propagating crack tips as water is injected into solutions of end-capped associating polymers in a rectanguar Hele-Shaw cell. Measurements were performed for flows with different values of cell gap, channel width, polymer molecular weight, and polymer concentration. The condition for the onset of fracturelike behavior is well described by a Deborah number which uses the shear-thinning shear rate of the polymer solution as a characteristic frequency for network relaxation. At low molecular weight, the onset of fracturelike pattern evolution is accompanied by an abrupt jump in tip velocity, followed by a lower and approximately constant acceleration. At high molecular weight, the transition to fracturelike behavior involves passing through a regime that may be understood in terms of stick-slip dynamics. The crack-tip wanders from side to side and fluctuates (in both speed and velocity along the channel) with a characteristic frequency which depends linearly on the invading fluid injection rate.

Velocity-jump instabilities in Hele-Shaw flow of associating polymer solutions

We study fracturelike flow instabilities that arise when water is injected into a Hele-Shaw cell filled with aqueous solutions of associating polymers. We explore various polymer architectures, molecular weights, and solution concentrations. Simultaneous measurements of the finger tip velocity and of the pressure at the injection point allow us to describe the dynamics of the finger in terms of the finger mobility, which relates the velocity to the pressure gradient. The flow discontinuities, characterized by jumps in the finger tip velocity, which are observed in experiments with some of the polymer solutions, can be modeled by using a nonmonotonic dependence between a characteristic shear stress and the shear rate at the tip of the finger. A simple model, which is based on a viscosity function containing both a Newtonian and a non-Newtonian component, and which predicts nonmonotonic regions when the non-Newtonian component of the viscosity dominates, is shown to agree with the experimental data.

Experiments on anisotropic radial viscous fingering

We observe dendritic patterns in fluid flow in an anisotropic Hele-Shaw cell and measure the tip shapes and trajectories of individual dendritic branches under conditions where the pattern growth appears to be dominated by surface tension anisotropy and also under conditions where kinetic effects appear dominant. In each case, the tip position depends on a power law in the time, but the exponent of this power law can vary significantly among flow realizations. Averaging many growth exponents a yields a =0.640.09 in the surface tension dominated regime and a =0.660.09 in the kinetic regime. Restricting the analysis to realizations when a is very close to 0.6 shows great regularity across pattern regimes in the coefficient of the temporal dependence of the tip trajectory.

Nanometer-scale oxidation of Si(100) surfaces by tapping mode atomic force microscopy

The nanometer¿scale oxidation of Si(100) surfaces in air is performed with an atomic force microscope working in tapping mode. Applying a positive voltage to the sample with respect to the tip, two kinds of modifications are induced on the sample: grown silicon oxide mounds less than 5 nm high and mounds higher than 10 nm (which are assumed to be gold depositions). The threshold voltage necessary to produce the modification is studied as a function of the average tip¿to¿sample distance.

Nanomechanical properties of molecular organic thin films

Using atomic force microscopy we have studied the nanomechanical response to nanoindentations of surfaces of highly oriented molecular organic thin films (thickness¿1000¿nm). The Young¿s modulus E can be estimated from the elastic deformation using Hertzian mechanics. For the quasi-one-dimensional metal tetrathiafulvalene tetracyanoquinodimethane E~20¿GPa and for the ¿ phase of the p-nitrophenyl nitronyl nitroxide radical E~2GPa. Above a few GPa, the surfaces deform plastically as evidenced by discrete discontinuities in the indentation curves associated to molecular layers being expelled by the penetrating tip.

Identification of GPx8 as a novel cellular substrate of the hepatitis C virus NS3-4A protease

Background: The hepatitis C virus (HCV) NS3-4A protease is not only an essential component of the viral replication complex and a prime target for a ntiviral intervention but also a key player i n the persistence and pathogenesis of HCV. It cleaves and thereby inactivates two crucial adaptor proteins in viral RNA sensing and innate immunity (MAVS and TRIF) as well as a phosphatase involved in growth factor signaling (TCPTP). T he aim of this study was to identify novel cellular substrates o f the N S3-4A protease and to investigate their role in the replication and pathogenesis of HCV. Methods: Cell lines inducibly expressing t he NS3-4A protease were analyzed in basal as well as interferon-α-stimulated states by stable isotopic l abeling using amino acids in cell culture (SILAC) coupled with protein separation and mass spectrometry. Candidates fulfilling stringent criteria for potential substrates or products of the NS3-4A protease were further i nvestigated in different experimental systems as well a s in liver biopsies from patients with chronic hepatitis C. Results: SILAC coupled with protein separation and mass spectrometry yielded > 5000 proteins of which 18 candidates were selected for further analyses. These allowed us to identify GPx8, a membrane-associated peroxidase involved in disulfide bond formation in the endoplasmic reticulum, as a n ovel cellular substrate of the H CV NS3-4A protease. Cleavage occurs at cysteine in position 11, removing the cytosolic tip of GPx8, and was observed in different experimental systems as well as in liver biopsies from patients with chronic hepatitis C. Further functional studies, involving overexpression and RNA silencing, revealed that GPx8 is a p roviral factor involved in viral particle production but not in HCV entry or HCV RNA replication. Conclusions: GPx8 is a proviral host factor cleaved by the HCV NS3-4A protease. Studies investigating the consequences of GPx8 cleavage for protein function are underway. The identification of novel cellular substrates o f the HCV N S3-4A protease should yield new insights i nto the HCV life cycle and the pathogenesis of hepatitis C and may reveal novel targets for antiviral intervention.

Néoplasie épithéliale de l'appendice: quoi de neuf [Epithelial neoplasia of the appendix: what has recently changed?].

Appendicular tumors are mostly found incidentally in up to 1.5% of all appendectomies. Neuroendocrine tumors are the commonest malignancies, and are associated with an excellent long-term prognosis. While small lesions located at the appendicular tip can be treated with simple appendectomy, advanced tumors require right hemicolectomy. Goblet cell carcinoids are rare tumors showing a mixed phenotype. Long-term outcome is impaired, and for most cases a right hemicolectomy is mandatory. Colonic-type adenocarcinomas have a similar behavior like conventional colonic cancer and should be treated similarly. Mucinous neoplasias possess the characteristic of extensive mucin production with intraperitoneal spread. Treatment options are ranging from right hemicolectomy to multivisceral resection with intraperitoneal chemotherapy.

Fast low-specific absorption rate B0 -mapping along projections at high field using two-dimensional radiofrequency pulses.

PURPOSE: At 7 Tesla (T), conventional static field (B0 ) projection mapping techniques, e.g., FASTMAP, FASTESTMAP, lead to elevated specific absorption rates (SAR), requiring longer total acquisition times (TA). In this work, the series of adiabatic pulses needed for slab selection in FASTMAP is replaced by a single two-dimensional radiofrequency (2D-RF) pulse to minimize TA while ensuring equal shimming performance. METHODS: Spiral gradients and 2D-RF pulses were designed to excite thin slabs in the small tip angle regime. The corresponding selection profile was characterized in phantoms and in vivo. After optimization of the shimming protocol, the spectral linewidths obtained after 2D localized shimming were compared with conventional techniques and published values from (Emir et al NMR Biomed 2012;25:152-160) in six different brain regions. RESULTS: Results on healthy volunteers show no significant difference (P > 0.5) between the spectroscopic linewidths obtained with the adiabatic (TA = 4 min) and the new low-SAR and time-efficient FASTMAP sequence (TA = 42 s). The SAR can be reduced by three orders of magnitude and TA accelerated six times without impact on the shimming performances or quality of the resulting spectra. CONCLUSION: Multidimensional pulses can be used to minimize the RF energy and time spent for automated shimming using projection mapping at high field. Magn Reson Med, 2014. © 2014 Wiley Periodicals, Inc.