第1038回千葉医学会例会・平成13年度千葉大学大学院医学研究院胸部外科学・基礎病理学例会

Heatmap of data sets correlation. Heatmap of correlation between selected genes expression profiles and monosaccharide content of cell wall (%NSP) or oligosaccharides relative content in glucanase digest during apple development and ripening. Positive and negative correlations are respectively shown in red and blue colours. (XLSX 28 kb

Contribution of cell wall-modifying enzymes to the texture of fleshy fruits. The example of apple

The cell walls of fleshy fruits consist of polysaccharide assemblies (pectin, hemicelluloses and cellulose), the structure and interactions of which vary depending on the genetics of the fruit, and its stage and conditions of development. The establishment and the structural reorganization of the assemblies result from enzyme/protein consortia acting in muro. The texture of fleshy fruits is one of the major criteria for consumer choice. It impacts also post-harvest routes and transformation processes. Disassembly of fruit cell wall polysaccharides largely induces textural changes during ripening but the precise role of each polysaccharide and each enzyme remains unclear. The changes of cell wall polysaccharides during fruit ripening have mainly emphasized a modulation of the fine chemical structure of pectins by hydrolases, lyases, and esterases. This restructuring also involves a reorganization of hemicelluloses by hydrolases/transglycosidases and a modulation of their interactions with the cellulose by non-catalytic proteins, such as expansin. Apple is the third most produced fruit in the world and has been the subject of studies about fruit quality. This paper presents some of the results to date about the enzymes//proteins involved in fruit ripening with particular emphasis on apple

Fine chemical structure analysis of oligosaccharides produced by an ulvan-lyase degradation of the water-soluble cell-wall polysaccharides from Ulva sp. (Ulvales, Chlorophyta)

International audienc

Interactions of the mix-linked beta-(1,3)/beta-(1,4)-D-xylans in the cell walls of Palmaria palmata (Rhodophyta)

International audienceAlgal cell wall mechanical properties, crucial for biological functions and commercial applications, rely on interactions in macromolecular assemblies. In an effort to better understand the interactions of the matrix-phase beta-(1,3)/(1,4)-d-xylan in the edible seaweed Palmaria palmata ((L.) O. Kuntze, Rhodophyta, Palmariales), sequential extractions by saline, alkaline, and chaotropic solutions were done. The chemical composition and structure and the physicochemical properties of the isolated xylan revealed that it was partly acidic, probably due to the presence of sulfate (up to 5%) and phosphate groups (up to 4%). Although such acidity suggested ionic interactions of xylan in the cell walls, the high yields of polysaccharide extracted by alkali and particularly by 8 M urea and 4.5 M guanidium thiocyanate demonstrated that it was mainly hydrogen bonded in the cell wall. H-bonds did not appear to be related to the mean proportions of beta-(1,3) and beta-(1,4)-d-xylose linkages because these did not differ between extracts of increasing alkalinity. However, the decreasing molar weight and intrinsic viscosity of extracts obtained by alkaline solution containing a reducing agent used to prevent polysaccharide degradation suggested the presence of an alkali-labile component in the xylan. These results are discussed with regard to the role of potential wall proteins as a means of control of these interactions

Regioselective synthesis of galactosyl-derivatives using exo-(1,4)-beta-D-galactanase, galactan, and nonsugar acceptors

International audienc

Initial observations on glycoside deposition in cell walls of Palmaria palmata (L.) Kuntze (Rhodophyta) during spore germination

International audienceThe cell wall fine structure of the red alga Palmaria palmata has been analysed extensively in recent years, but cell wall biosynthesis has not. The glycosidic composition of the cell walls of gametophytic and sporophytic fronds revealed no differences between the two stages. Spores were isolated from mature sporophytes and cultivated in vitro. Spore settlement, germination and first stages of germling development were described in terms of glycoside composition. Isolated spores were surrounded by a cell wall composed of xylose, galactose and glucose. During germination and germling development, the xylose content increased to the level of glycosides found in erect fronds, concurrently with starch degradation. Spores isolated from Palmaria palmata appeared to be good candidates for studying cell wall biosynthesis

Hemicellulose fine structure in apple as investigated by enzymatic profilling

National audienc

Novel fine structure in apple hemicelluloses as revealed by enzymatic profiling

International audienc

New enzymes from hemicellulolytic bacteria to enhance the biomass saccharification

absen