Uptake of insecticides and fungicides by impregnable and refractory coniferous wood species treated with commercial bio-based emulsion gel formulations

Even in dry state, wood can be prone to biological degradation. Preservation is a prerequisite to confer protection and durability to wood. This is conventionally achieved by impregnating the wood with pesticides. A key point in these treatments is the complex process of wood penetrability. We focused on the relation between the penetration of wood preservatives, wood microstructure, and the physical characteristics of formulations in the impregnation of the easily impregnable pine (Pinus sylvestris), and the refractory spruce (Picea abies). In this work, specimens from the two species were impregnated with three types of commercial bio-based emulsion gels formulations containing insecticides and fungicides. The effect of treatment method using dipping, surface spraying, and vacuum-impregnation, on the retention of the active agents was analyzed. Visual assessment, and qualitative and quantitative analyses of cypermethrin, permethrin and  propiconazole by gas liquid chromatography coupled to mass spectroscopy showed enhanced penetration of the active agents, and revealed differences of penetration performance of each agent. The suitable combinations of solvents and surfactants used in the bio-based formulations enabled rapid wood penetration and high yields retention. The capacity of penetration and retention of our gel formulations is discussed in terms of the connectivity of the conducting cells network of the two wood species

Quantification of the CBD-FITC conjugates surface coating on cellulose fibres

<p>Abstract</p> <p>Background</p> <p>Cellulose Binding Domains (CBD) were conjugated with fluorescein isothiocyanate (FITC). The surface concentration of the Binding Domains adsorbed on cellulose fibres was determined by fluorescence image analysis.</p> <p>Results</p> <p>For a CBD-FITC concentration of 60 mg/L, a coating fraction of 78% and 110% was estimated for <it>Portucel </it>and Whatman fibres, respectively. For a saturating CBD concentration, using Whatman CF11 fibres, a surface concentration of 25.2 × 10^-13mol/mm²was estimated, the equivalent to 4 protein monolayers. This result does not imply the existence of several adsorbed protein layers.</p> <p>Conclusion</p> <p>It was verified that CBDs were able to penetrate the fibres, according to confocal microscopy and TEM-immunolabelling analysis. The surface concentration of adsorbed CBDs was greater on amorphous fibres (phosphoric acid swollen) than on more crystalline ones (Whatman CF11 and Sigmacell 20).</p

The wood cell wall at the ultrastructural scale formation and topochemical organization

The macromolecular organization of the secondary wall of the cells from tree xylem is in large part responsible for the mechanical and physiological properties of wood. Modeling secondary walls of wood is difficult because information about their macromolecular architecture at the ultrastructural scale is missing. Numerous microscopic studies have provided views of the lignocellulosic composite material, but nanoscale distribution of the polymers and their interaction in muro is still not clearly understood. The intimate macromolecular organization of cell walls is defined during their differentiation. It is at the stage of wall thickening corresponding to secondary wall development that the topochemical organization and the interactions between cellulose, hemicelluloses and lignin are established.Using the conjunction of the high resolution of transmission electron microscopy (TEM) and the specificity of immunological probes directed against the main cell wall polymers, we investigated the deposition of hemicelluloses and lignins from the early stage of cambium differentiation to the mature fiber and vessel walls in growing model plants of Arabidopsis thaliana and poplar. TEM examination of differentiating cells as well as various wood and wood –derived materials and genetic plant mutants brought multiple evidence of the lamellar sub-organization of the secondary walls. Immuno-gold labeling showed that two structurally different xylan types were deposited at different stages in the wall thickening. Similarly two different types of lignin molecules were shown to be differentially polymerized at different steps of the building of the wall, lignin molecules of the condensed type being first deposited at the earliest stage of secondary thickening before the non-condensed  types. This process may be modified in response to environmental factors, as in tension wood.The spatio-temporal relationships occurring between hemicelluloses, lignin and cellulose microfibrils (CMFs) during the secondary wall development suggest that xylans with less substituted chains would be more directly interacting with CMFs than those with higher substitution patterns. It also suggests that lignin molecules of the non-condensed type have a function in bringing cohesion between the lamellae of CMFs. A model of wall assembly during secondary thickening is proposed

ZmXTH1, a new xyloglucan endotransglucosylase/hydrolase in maize, affects cell wall structure and composition in Arabidopsis thaliana

15 pages, 9 figures.-- PMID: 18316315[PubMed].-- Supporting information available at: http://jxb.oxfordjournals.org/content/59/4/875/suppl/DC1Xyloglucan endotransglucosylase/hydrolases (XTHs; EC 2.4.1.207 and/or EC 3.2.1.151) are enzymes involved in the modification of cell wall structure by cleaving and, often, also re-joining xyloglucan molecules in primary plant cell walls. Using a pool of antibodies raised against an enriched cell wall protein fraction, a new XTH cDNA in maize, ZmXTH1, has been isolated from a cDNA expression library obtained from the elongation zone of the maize root. The predicted protein has a putative N-terminal signal peptide and possesses the typical domains of this enzyme family, such as a catalytic domain that is homologous to that of Bacillus macerans beta-glucanase, a putative N-glycosylation motif, and four cysteine residues in the central and C terminal regions of the ZmXTH1 protein. Phylogenetic analysis of ZmXTH1 reveals that it belongs to subgroup 4, so far only reported from Poaceae monocot species. ZmXTH1 has been expressed in Pichia pastoris (a methylotrophic yeast) and the recombinant enzyme showed xyloglucan endotransglucosylase but not xyloglucan endohydrolase activity, representing the first enzyme belonging to subgroup 4 characterized in maize so far. Expression data indicate that ZmXTH1 is expressed in elongating tissues, modulated by culture conditions, and induced by gibberellins. Transient expression assays in onion cells reveal that ZmXTH1 is directed to the cell wall, although weakly bound. Finally, Arabidopsis thaliana plants expressing ZmXTH1 show slightly increased xyloglucan endohydrolase activity and alterations in the cell wall structure and composition.This work was funded by the Spanish ‘Ministerio de Ciencia y Tecnología’ (BIO2001-1140). VG was financed by a pre-doctoral grant from the ‘Generalitat de Catalunya’ (2003-FI00090). In addition, VG was funded by two grants from the Generalitat de Catalunya (2005-BE00104 and 2006-BE00668) for her work performed at Professor Fry's and Dr Ruel's laboratories. SF was financed by a post-doctoral grant from the ‘Generalitat de Catalunya’ (2003PIV-A-00033) and by an I3P contract from the ‘Consejo Superior de Investigaciones Científicas’. DC-R was financed by the Spanish ‘Ministerio de Educacion y Ciencia’ (‘Ramon y Cajal’ Program). This work was carried out within the framework of the ‘Xarxa de Referència en Biotecnologia’ from the ‘Generalitat de Catalunya’. SCF was funded by the UK Biotechnology and Biological Sciences Research Council. We are indebted to Dr Castresana (IBMB-CSIC) for his advice on the phylogenetic analyses, Dr Capellades for her technical support and the sequencing, and the greenhouse teams of IBMB-CSIC.Peer reviewe

Etude biochimique et immunocytochimique de l impact de mutations génétiques sur la lignification et l assemblage des parois d Arabidopsis thaliana

La biomasse végétale suscite un intérêt accru en raison de son potentiel pour les énergies de remplacement du pétrole. Dans toutes ces formes d utilisation et de valorisation, la paroi cellulaire lignocellulosique occupe un rôle central. C est dans ce contexte d une meilleure connaissance de la structure fine de la paroi secondaire lignifiée et de la fonction des polymères constitutifs dans l élaboration du biocomposite qu est la paroi que se situent les travaux réalisés dans le cadre de cette thèse. Plusieurs mutants nuls de la plante modèle Arabidopsis thaliana, dont un ou plusieurs gènes (cinnamoyl-CoA-réductase, mutant ccr1 ; cinnamyl alcohol deshydrogénase, mutants cad-c et cad-d ; aldéhyde déshydrogénase, mutant ref1 ; férulate 5-hydroxylase, mutant f5h) impliqués dans la synthèse des alcools coniférylique et sinapylique, précurseurs des unités G et S des lignines, ont été totalement réprimés, ont constitué les modèles utilisés pour étudier les effets de la mutation sur la composition et la structure des parois. L analyse biochimique des lignines des plantes mutantes par thioacidolyse, d une part, et l étude à l échelle ultrastructurale par immunomarquage en microscopie électronique, d autre part, ont constitué les deux principales approches complémentaires privilégiées par lesquelles il a été possible de décrire les impacts des mutations sur la structure des lignines et par là sur l assemblage macromoléculaire des parois. Les conséquences des mutations se sont avérées tissu-spécifiques et suggèrent une régulation spatio-temporelle de la lignification accompagnant la différenciation. La comparaison des altérations induites dans l assemblage des parois par les différentes mutations a permis de déduire que les structures non-condensées des lignines assuraient un rôle important dans la cohésion du composite cellulose-hémicelluloses-lignines. L analyse des impacts des mutations simples ou multiples des différents gènes montre que les effets sur les lignines et les parois ne correspondent pas à la simple sommation des effets de chacune des mutations des gènes, suggérant des régulations croisées. Le développement d une nouvelle approche de microanalyse impliquant la microdissection à capture laser a permis de préciser pour la première fois les différences analytiques des lignines des fibres par rapport aux vaisseaux, et a montré tout son potentiel pour l analyse de l impact des mutations à l échelle tissulaire.In recent years plant biomass has become the subject of a large interest for the industrial uses of wood and agricultural residues and for its potential use for new energy sources. For all these utilisations the lignocellulosic cell wall plays a central role. The work of this thesis was undertaken to gain an improved knowledge of the detailed structure and organisation of the lignified secondary wall and of the function of the polymer constituents in the edification of the plant cell wall biocomposite. Several knock-out mutants of the model plant Arabidopsis thaliana deficient for one or more genes involved in lignin monomers biosynthesis (cinnamoyl-CoA-reductase, ccr1; cinnamyl alcohol dehydrogenase, cad-c and cad-d; aldehyde dehydrogenase, ref1 ; ferulate 5-hydroxylase, f5h) were investigated for the analysis of the consequences of the mutation on the composition and the structure of the cell walls. Biochemical analysis of the mutant lines by thioacidolysis, and immuno-topochemistry in electron microscopy, respectively, constituted the two main approaches implemented to characterise the impacts of the mutations on the structure of lignins and on the macromolecular assembly of the cell walls. Our results revealed that the consequences of the mutations were tissue-specific, suggesting that lignification is spatio-temporally regulated during differentiation. The analysis of the alterations induced by the different mutations in the assembly of the cell walls suggested that the non-condensed structures of lignin had an important role in the cohesion of the cell wall composite. The comparison of the impacts of the different genes and gene combinations showed that the effects on the lignins and on the walls are not the simple summation of the effect of each individual gene. The development of a new approach of microanalysis involving the technique of laser capture microdissection allowed to precise for the first time the analytical differences of the lignins from fibres and vessels, and showed a great potential for the characterisation of the effects of mutations at the tissue scale.GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

Differentiation of xylem cells in rolC transgenic aspen trees - a study of secondary cell wall development

International audienceXylem cell differentiation of 35S-rolC transgenic aspen was analyzed and compared with wild type trees. The transgenic trees, mainly characterized by dwarfism and physiological alterations, did not show distinctive differences in the structure and chemical composition of xylem cell walls as compared with the wild type trees. However, there was a difference in the dynamics of differentiation. In the transgenics the formation of xylem cells was delayed and the differentiation zone reduced to a few rows. PATAg and KMnO$_4$ staining in electron microscopy as well as UV-microspectrophotometry revealed that in the transgenics during secondary wall formation polysaccharides and lignin were simultaneously deposited close to the cambium. Immunocytochemical techniques have visualized the first deposition of condensed lignin in cell corners and of non-condensed lignin in secondary walls near cell corners. Because of altered formation and differentiation of xylem cells, 35S-rolC transgenic aspen may be useful to study factors controlling the differentiation continuum.Différenciation des cellules du xylème chez le peuplier transgénique 35S-rolC - une étude de la formation des parois secondaires. La différenciation des cellules du xylème du peuplier transgénique 35S-rolC a été analysée et comparée à celle du peuplier non transformé. Les arbres transgéniques nains, qui se caractérisent par des altérations physiologiques et morphologiques ne présentaient pas de différences dans leur architecture ni dans la composition des parois des cellules du xylème par comparaison avec les plantes normales. En revanche, on a pu observer une différence dans la dynamique de la différenciation. Dans les arbres transgéniques, la formation des cellules du xylème est retardée et la zone de différenciation est réduite à quelques rangées de cellules. De ce fait, la formation et la lignification de la paroi secondaire ont pu être observées dans des cellules moins développées que dans le peuplier normal ainsi que cela a été mis en évidence par microspectrophotométrie-UV et par les contrastants PATAg et KMnO$_4$ en microscopie électronique à transmission. Des analyses immunocytochimiques ont révélé la toute première déposition de lignines condensées dans les jonctions intercellulaires et de lignines non condensées dans les parois secondaires adjacentes aux triangles de jonctions. Ces altérations dans la formation et la différenciation des cellules du xylème font du peuplier transgénique 35S-rolC un matériel utile pour l'étude des facteurs contrôlant le continuum de différenciation

Uptake of insecticides and fungicides by impregnable and refractory coniferous wood species treated with commercial bio-based emulsion gel formulations

Even in dry state, wood can be prone to biological degradation. Preservation is a prerequisite to confer pro-tection and durability to wood. This is conventionally achieved by impregnating the wood with pesticides.A key point in these treatments is the complex process of wood penetrability. We focused on the relation between the penetration of wood preservatives, wood microstructure, and the physical characteristics of formulations in the impregnation of the easily impregnable pine (Pinus sylvestris), and the refractory spruce (Picea abies). In this work, specimens from the two species were impregnated with three types of commercial bio-based emul-sion gels formulations containing insecticides and fungicides. The effect of treatment method using dipping, surface spraying, and vacuum-impregnation, on the retention of the active agents was analyzed. Visual assess-ment, and qualitative and quantitative analyses of cypermethrin, permethrin and propiconazole by gas liquid chromatography coupled to mass spectroscopy showed enhanced penetration of the active agents, and revealed differences of penetration performance of each agent. The suitable combinations of solvents and surfactants used in the bio-based formulations enabled rapid wood penetration and high yields retention. The capacity of penetration and retention of our gel formulations is discussed in terms of the connectivity of the conducting cells network of the two wood specie