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Biomedical subjects

J Leymarie

Publications and source records attributed to J Leymarie.

8 recordsLinked to original sources
PubMed2004

Mie resonances, infrared emission, and the band gap of InN.

Mie resonances due to scattering or absorption of light in InN-containing clusters of metallic In may have been erroneously interpreted as the infrared band gap absorption in tens of papers. Here we show by direct thermally detected optical absorption measurements that the true band gap of InN is markedly wider than the currently accepted 0.7 eV. Microcathodoluminescence studies complemented by the imaging of metallic In have shown that bright infrared emission at 0.7-0.8 eV arises in a close vicinity of In inclusions and is likely associated with surface states at the metal/InN interfaces.

Journal Article↗
PubMed1999

Arabidopsis contains at least four independent blue-light-activated signal transduction pathways.

We have investigated the stomatal and phototropic responses to blue light of a number of single and double mutants at various loci that encode proteins involved in blue-light responses in Arabidopsis. The stomatal responses of light-grown mutant plants (cry1, cry2, nph1, nph3, nph4, cry1cry2, and nph1cry1) did not differ significantly from those of their wild-type counterparts. Second positive phototropic responses of etiolated mutant seedlings, cry1, cry2, cry1cry2, and npq1-2, were also similar to those of their wild-type counterparts. Although npq1 and single and double cry1cry2 mutants showed somewhat reduced amplitude for first positive phototropism, threshold, peak, and saturation fluence values for first positive phototropic responses of etiolated seedlings did not differ from those of wild-type seedlings. Similar to the cry1cry2 double mutants and to npq1-2, a phyAphyB mutant showed reduced curvature but no change in the position or shape of the fluence-response curve. By contrast, the phototropism mutant nph1-5 failed to show phototropic curvature under any of the irradiation conditions used in the present study. We conclude that the chromoproteins cry1, cry2, nph1, and the blue-light photoreceptor for the stomatal response are genetically separable. Moreover, these photoreceptors appear to activate separate signal transduction pathways.

Arabidopsis↗
PubMed1996

Nucleotide sequences of four pathogen-induced alfalfa peroxidase-encoding cDNAs.

We constructed an alfalfa cDNA library from mRNA extracted from leaves after infection with Pseudomonas syringae (incompatible interaction). Screening with oligodeoxyribonucleotides designed from regions conserved in all known peroxidases allowed the isolation of four cDNAs (Msprx1A, 1B, 1C and 2). Sequence analysis revealed the presence of open reading frames of 351, 355, 358 and 323 amino acids, respectively, with the characteristic consensus sequences of plant peroxidases. Sequence comparison showed that the Msprx2 product is significantly different from the others and, particularly, lacks a C-terminal propeptide which might be required for vacuolar targeting.

Amino Acid Sequence↗
PubMed1996

Two-dimensional protein patterns of Arabidopsis wild-type and auxin insensitive mutants, axr1, axr2, reveal interactions between drought and hormonal responses.

In order to detect gene products involved in Arabidopsis drought adaptive strategy, 2D-PAGE protein patterns of two auxin-insensitive mutants, axr1, axr2, differentially affected in specific drought responses, were compared to the wild-type Columbia ecotype, in well-watered and drought-stressed conditions. Coupled to computer analysis of polypeptide amounts, 2D-electrophoresis revealed subtle changes in protein expression induced by progressive drought stress and/or mutations affecting the auxin response pathway. The differential protein patterns of axr1 and axr2 were consistent with their contrasting drought responses. The specific leaf and root protein patterns of axr1 showed that this mutation disrupts drought responses related to auxin regulation. In particular, the near absence of drought rhizogenesis in axr1 was associated with a root protein pattern closer to the well-watered than to the water-stressed axr2 and Columbia wild-type root protein patterns. Also, the largely different effects of axr1 and axr2 mutations suggest that they affect different pathways in auxin response. Several sets of polypeptides, whose regulation was affected by drought and/or mutation, were thus detected. These polypeptides could play a role both in the auxin and the drought response pathways. Their identification, through microsequencing, should be most informative.

Arabidopsis↗
PubMed1993

Glaphenine-containing gallstones.

Glaphenine is an analgesic drug derived from anthranilic acid. We report the analytical procedures for stone analysis in three cases of common bile duct stones containing glaphenic acid, which developed in arthrosic patients treated for 13.7 +/- 5 years with glaphenine. Stone analysis was performed by infrared spectroscopy, high performance thin layer chromatography, scanning electron microscopy and energy dispersive X-ray analysis. Mechanisms of lithogenesis are discussed. These observations emphasize the possibility of radiolucent gallstones mainly composed of drug compounds.

Aged↗