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A Boudet

Publications and source records attributed to A Boudet.

18 recordsLinked to original sources
PubMed2001

Elucidation of new structures in lignins of CAD- and COMT-deficient plants by NMR.

Studying lignin-biosynthetic-pathway mutants and transgenics provides insights into plant responses to perturbations of the lignification system, and enhances our understanding of normal lignification. When enzymes late in the pathway are downregulated, significant changes in the composition and structure of lignin may result. NMR spectroscopy provides powerful diagnostic tools for elucidating structures in the difficult lignin polymer, hinting at the chemical and biochemical changes that have occurred. COMT (caffeic acid O-methyl transferase) downregulation in poplar results in the incorporation of 5-hydroxyconiferyl alcohol into lignins via typical radical coupling reactions, but post-coupling quinone methide internal trapping reactions produce novel benzodioxane units in the lignin. CAD (cinnamyl alcohol dehydrogenase) downregulation results in the incorporation of the hydroxycinnamyl aldehyde monolignol precursors intimately into the polymer. Sinapyl aldehyde cross-couples 8-O-4 with both guaiacyl and syringyl units in the growing polymer, whereas coniferyl aldehyde cross-couples 8-O-4 only with syringyl units, reflecting simple chemical cross-coupling propensities. The incorporation of hydroxycinnamyl aldehyde and 5-hydroxyconiferyl alcohol monomers indicates that these monolignol intermediates are secreted to the cell wall for lignification. The recognition that novel units can incorporate into lignins portends significantly expanded opportunities for engineering the composition and consequent properties of lignin for improved utilization of valuable plant resources.

Alcohol Oxidoreductases↗
PubMed2001

Reassessment of qualitative changes in lignification of transgenic tobacco plants and their impact on cell wall assembly.

In tobacco plants the effect of antisense down-regulation of various genes encoding enzymes of the monolignol biosynthetic pathway resulted in quantitative and qualitative changes in lignin distribution and in diverse alterations of the secondary wall assembly of modified tobacco plants. Total lignin content, composition in syringyl and guaiacyl units, and absolute proportions of condensed and non-condensed substructures occurring in the cell walls, were differentially modified according to the repressed gene. Immunocytochemical characterisation and visualisation of the distribution of condensed and non-condensed lignin substructure epitopes in transmission electron microscopy (TEM) revealed that some transformations entailed profound and specific alterations in the secondary wall biogenesis. Correlation between micro-morphological cell wall alterations and semi-quantitative immuno-analysis of the topochemical distribution of lignin sub-units suggests that the mode of polymerisation of monolignols into non-condensed units, favoured by the microfibril matrix of the secondary wall, plays an important part in the lignified cell wall assembly.

Cell Wall↗
PubMed2001

Glassy cholesteric structure: thickness variation induced by electron radiation in transmission electron microscopy investigated by atomic force microscopy.

During the observation of glassy cholesteric liquid crystals in transmission electron microscopy (TEM), a new contrast is created or enhanced by electron radiation which has a direct relationship with the periodic microstructure of the specimen. In this paper, we investigate the variations of the sample thickness and mass density as possible causes of this irradiation contrast. By means of observations in atomic force microscopy (AFM) coupled to TEM, we compared the surface corrugations of non-irradiated and irradiated specimens. It is shown that the final contrast is the result of several processes. including fracture during ultramicrotomy and mass loss during irradiation. Mass loss acts as an etching, and hence results in a decrease of the sample thickness. The etching depends on the initial molecular orientation, thus evidencing the latent structure. An electron channelling mechanism is suggested to explain this behaviour.

Journal Article↗
PubMed1998

Immunolocalization of cinnamyl alcohol dehydrogenase 2 (CAD 2) indicates a good correlation with cell-specific activity of CAD 2 promoter in transgenic poplar shoots.

Cinnamyl alcohol dehydrogenase 2 (CAD 2) localization and the cell-specific activity of the eucalyptus CAD 2 promoter were investigated by CAD 2 immunogold localization and promoter beta-glucuronidase (GUS) histochemistry in apical and mature parts of stable transformed poplar (Populus tremula x P. alba) stems. Both CAD 2 protein and GUS activity were found to be confined in the same types of cells in the shoot apices, particularly in the determined meristematic cells in leaf axils and shell zones, procambium and developing tracheids. Within mature stems, CAD 2 and GUS were also identified in cambium and in fully or partially lignified cells derived from it (young xylem, developing phloem fibres, chambered parenchyma cells around phloem). Additionally, GUS activity was found in the scale leaves of apical shoot buds and in the roots (namely in the procambium, cambium, phellogen, young xylem, pericycle) of transformed plants. By employing immunogold cytochemistry, CAD 2 was shown to be localized in the cytoplasm within cambial, ray and young xylem cells in stems, the gold particles being randomly attached to endoplasmic reticulum and Golgi-derived vesicles. These results support a crucial role for CAD 2 in lignification and indicate a new role for this enzyme in branching events within the shoot apex and during lateral root formation.

Alcohol Oxidoreductases↗
PubMed1995

Tissue- and cell-specific expression of a cinnamyl alcohol dehydrogenase promoter in transgenic poplar plants.

Cinnamyl alcohol dehydrogenase (CAD) which catalyses the synthesis of the cinnamyl alcohols, the immediate precursors of lignins, from the corresponding cinnamaldehydes is considered to be a highly specific marker for lignification. We have isolated and characterized a CAD genomic clone from eucalyptus, a woody species of economic importance. The full-length promoter (EuCAD, 2.5 kb) and a series of 5' deletions were fused to the beta-glucuronidase (GUS) reporter gene. These constructs were tested in a homologous transient expression system of eucalyptus protoplasts which enabled the identification of several regions involved in transcriptional control. In order to study the spatial and developmental regulation of the CAD gene, the chimeric gene fusion (EuCAD-GUS) was then transferred via Agrobacterium tumefaciens-mediated transformation into poplar, an easily transformable woody angiosperm. Quantitative fluorometric assays conducted on eight independent in vitro transformants showed that GUS activity was highest in roots followed thereafter by stems and leaves. Histochemical staining for GUS activity on both in vitro primary transformants and more mature greenhouse-grown plants indicated a specific expression in the vascular tissues of stems, roots, petioles and leaves. At the onset of xylem differentiation, GUS activity was detected in parenchyma cells differentiating between the xylem-conducting elements. After secondary growth has occurred, GUS activity was localized in xylem ray cells and parenchyma cells surrounding the lignified phloem and sclerenchyma fibers. This first characterization of a woody angiosperm CAD promoter provides functional evidence for the role of CAD in lignification and suggests that parenchyma cells expressing CAD may provide lignin precursors to the adjacent lignified elements (vessels and fibres).

Alcohol Oxidoreductases↗
PubMed1994

Purification and characterization of cinnamyl alcohol dehydrogenase isoforms from Phaseolus vulgaris.

Cinnamyl alcohol dehydrogenase (CAD) catalyses the reduction of hydroxycinnamaldehydes (p-coumaryl, coniferyl, sinapyl) to the corresponding alcohols which are the monomeric precursors of lignins. We have demonstrated the occurrence of two isoforms of CAD (CAD1 and CAD2) in bean which differ in terms of subunit Mr, specific activity, substrate affinity and antigenicity. The most abundant polypeptide in bean pods, organs with very limited lignification, is a low affinity CAD isoform (CAD1). This enzyme which is distinct from a benzyl alcohol dehydrogenase with broad substrate specificity, was purified to apparent homogeneity and partial amino acid sequencing was carried out using internal peptides obtained by trypsin cleavage.

Alcohol Oxidoreductases↗
PubMed1993

[Metabolic improvement of diabetes mellitus through pamphlets on the norms of self-monitoring control measures].

OBJECTIVE: To assess whether giving a leaflet containing norms of self-control to diabetics receiving insulin treatment results in a metabolic improvement. The HbA1c was established prior and subsequent to giving out the leaflet. The written norms contained in the leaflet were highlighted from the wider range of instructions obtained from diabetes education. DESIGN: A longitudinal intervention study with no random allocation. SETTING: Hospital care in a specialised Endocrinology clinic. PATIENTS AND OTHER PARTICIPANTS: 122 types 1 and 2 diabetics, treated with various insulin diets, who had received prior diabetes education and carried out blood self-controls. Cases of meta-diabetic syndrome, serious illnesses and those without apparent hypoglycaemia symptoms were excluded. INTERVENTIONS: Giving out of a leaflet with written norms of self-control. MEASUREMENTS AND MAIN RESULTS: The averages, standard deviations and 95% confidence intervals of the basal HbA1c and of those at four-monthly check-ups were calculated. Basal 8.07 (CI 7.75 - 8.39); 4th month 6.88 (CI 6.74 - 7.17); 8th month 6.59 CI 6.29 - 6.90); 12th month 6.60 (CI 6.23 - 6.94); 16th month 6.06 (CI 5.63 - 6.49); 20th month 5.40 (CI 3.04 - 7.75). Averages were compared by the Student T test and all values had p < 0.005 against the basal. CONCLUSIONS: Following the written norms produced a clear metabolic improvement, represented by the significant fall of HbA1c. Therefore, though without ignoring the overall context of treatment and diabetes education, it is proposed that the relationship of the most practical features of insulin dosing to written norms of self-control should be emphasised.

Blood Glucose Self-Monitoring↗
PubMed1992

Purification and characterization of cinnamyl alcohol dehydrogenase from tobacco stems.

Cinnamyl alcohol dehydrogenase (CAD) is an enzyme involved in lignin biosynthesis. In this paper, we report the purification of CAD to homogeneity from tobacco (Nicotiana tabacum) stems. The enzyme is low in abundance, comprising approximately 0.05% of total soluble cell protein. A simple and efficient purification procedure for CAD was developed. It employs three chromatography steps, including two affinity matrices, Blue Sepharose and 2'5' ADP-Sepharose. The purified enzyme has a specific cofactor requirement for NADP and has high affinity for coniferyl alcohol (K(m) = 12 micromolar) and coniferaldehyde (K(m) = 0.3 micromolar). Two different sized polypeptide subunits of 42.5 and 44 kilodaltons were identified and separated by reverse-phase HPLC. Peptide mapping and amino acid composition analysis of the polypeptides showed that they are closely related, although not identical.

Journal Article↗
PubMed1984

Induction of phenylalanine ammonia-lyase and 4-coumarate:CoA ligase mRNAs in cultured plant cells by UV light or fungal elicitor.

The mRNAs encoding two enzymes of phenylpropanoid metabolism, phenylalanine ammonia-lyase (PAL; EC 4.3.1.5) and 4-coumarate:CoA ligase (4CL; EC 6.2.1.12), were induced in cultured parsley cells (Petroselinum hortense) either by irradiation with UV light or by treatment with elicitor, a cell-wall fraction of the fungus Phytophthora megasperma f. sp. glycinea. Two-dimensional gel electrophoresis of the encoded PAL and 4CL proteins revealed that the mRNAs induced by either treatment were very similar if not identical. RNA blot hybridization with cDNAs complementary to these mRNAs was used to measure changes in the mRNA amounts at various times after either treatment. Total cellular PAL and 4CL mRNA amounts increased coordinately after UV irradiation to a maximum at 7 hr and then decreased to uninduced levels by 30 hr with the same kinetics as observed previously for the changes in the translational activities. Treatment with the fungal elicitor also caused coordinated, but more rapid, changes in PAL and 4CL mRNA translational activities, with a sharp peak occurring 3 hr after the addition of elicitor. Corresponding changes in mRNA amounts were observed only for 4CL, whereas the amount of PAL mRNA continued to increase at least up to 20 hr after elicitor addition. Our results suggest that parsley cells respond to UV irradiation or addition of fungal elicitor by increased rates of transcription of genes involved in the synthesis of compounds related to UV or disease resistance, respectively.

Journal Article↗
PubMed1975

The measurement of protein turnover by density labelling.

A method for measuring the rate of protein degradation in plant tissue is described. The method uses density labelling to avoid difficulties associated with compartmentation and recycling of amino acids. Although the technique cannot be readily adapted to measure the rate of degradation of single proteins, it avoids difficulties of interpretation due to enzyme activation or inactivation. Values for the half-life of Lemna minor protein obtained by this method are compared with values obtained by a number of other methods. To obtain satisfactory results it was necessary to improve the method of isopycnic centrifugation in CsCl gradients. A considerable improvement was achieved by using KBr gradients, and the advantages of using KBr rather than CsCl for the separation of density-labelled protein are discussed.

Amino Acids↗
PubMed1971

Mise en evidence chez les vegetaux superieurs d'une association enzymatique bifonctionnelle intervenant dans la biosynthese de l'acide shikimique.

In the extracts of Quercus pedunculata roots, the activities of 5-dehydroquinate hydro-lyase and shikimate: NADP oxydoreductase are eluted in the same fractions whatever separation procedures are used: chromatography on Sephadex G 100, DEAE cellulose and hydroxylapatite, centrifugation in sucrose density gradient, disc electrophoresis. These results are closely related to those obtained on the aggregate of enzymes involved in the shikimate pathway in Neurospora crassa. The molecular weight of the association determined by gel filtration is about 55,000.

Journal Article↗
PubMed1970

[Men 47, XYY].

Explore the source record for details and available documents.

Body Height↗
PubMedDate not supplied

[Action and tolerance of dothiepin hydrochloride (Prothiaden) in depressive states during the evolution of psychotic disorders].

During psychosis evolution, depressions occur frequently with a prevalence between 10% and 70% (average 25%-50%). Depression aggravates psychosis prognosis by increasing the risk of suicide, relapse and hospitalization. So antidepressant and neuroleptic treatments are often associated. Many studies with contradictory results were realized. Some concluded a favourable effect of this association, others considered this concomitant medication aggravates psychotic symptoms and adverse reactions. However this association appears to be efficient especially in deficitary or depressive forms of schizophrenia. The objective of this multicentre, non comparative, open study is to assess during 6 weeks the efficacy and tolerability of dothiepin in the treatment of depression occurring during the evolution of psychosis. The initial score on HDRS (17 items) had to be at least 18. 124 patients (40.7 years, 63.1% male) suffering from chronic psychosis associated with depressive syndrome were included in 29 hospital centres. According to DSM III-R criteria, 71.9% of patients were schizophrenic and 43% were suffering from major depressive illness. 16 patients (12.9%) stopped prematurely the treatment and side effects were reported for 8 of them. Any unexpected side effect occurred and pre-existing psychotic disorders reappeared for one patient. During the whole study, 63% of the population were treated with 75 mg as daily dosage of dothiepin. All concomitant treatments except antidepressant were authorized. 115 patients (95%) received at least one associated neuroleptic treatment and 54 patients (44.6%) a concomitant antiparkinsonian treatment. The significant decrease, between day 0 and day 45, of the global score on HDRS (from 23.78 to 8.48, p < 0.01), confirms the improvement of depression.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗