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With today's interest in novel renewable chemicals and polymers, the underexploited marine green algae belonging to species of Ulva and Entermorpha stimulated interest as sources of polysaccharides with innovative structure and functional properties. These algae are common on all seashores and can produce in time an important amount of biomass in(More)
Pectins are a highly complex family of cell wall polysaccharides. As a result of a lack of specific mutants, it has been difficult to study the biosynthesis of pectins and their role in vivo. We have isolated two allelic mutants, named quasimodo1 (qua1-1 and qua1-2), that are dwarfed and show reduced cell adhesion. Mutant cell walls showed a 25% reduction(More)
In order to obtain information on sugar sequences in the water soluble polysaccharides from Ulva "rigida", oligosaccharides were purified by anion exchange and gel permeation chromatography from the partial acid hydrolysate of the native or desulfated ulvan. The chemical structure and sugar sequence of these oligomers were determined by 1H and 13C NMR(More)
The chemical structure and the sequence of repeating units in ulvans of similar compositions from two different Ulva rigida samples collected in the Canary Islands and in Brittany were studied after ulvan-lyase degradation and NMR spectroscopic analysis of the reaction products. Both ulvans were composed of ulvanobiuronic acid 3-sulfate type A(More)
The GDP-D-mannose 3,5-epimerase (GME, EC, which converts GDP-d-mannose to GDP-l-galactose, is generally considered to be a central enzyme of the major ascorbate biosynthesis pathway in higher plants, but experimental evidence for its role in planta is lacking. Using transgenic tomato lines that were RNAi-silenced for GME, we confirmed that GME(More)
A marine bacterium degrading the water-soluble cell wall polysaccharides from Ulva sp. (ulvan) has been isolated. The good correlation between ulvan degradation monitored by reducing-power, UV absorbance and viscosimetry, indicated that the crude enzymatic extract contains essentially an endo-ulvan lyase activity. This activity was rapidly inhibited by the(More)
Fruit ripening and softening are key traits for many fleshy fruit. Since cell walls play a key role in the softening process, expansins have been investigated to control fruit over ripening and deterioration. In tomato, expression of Expansin 1 gene, SlExp1, during fruit ripening was associated with fruit softening. To engineer tomato plants with long shelf(More)
Ulvans (from Ulva lactuca) constitute a dietary fiber structurally similar to the mammalian glycosaminoglycans but with unexplored biological or cytotoxic activities. From native low-viscosity preparations containing 33.5 molar % and 18.4 molar % of sulfate residues and uronic acid residues, respectively, we derived desulfated, reduced and(More)
The seasonal variability in the extraction yield, physicochemical characteristics, and rheological properties of ulvan from two Ulva species contributing to Brittany "green tides" has been studied. These seaweeds were collected in the water column for Ulva armoricana Dion, de Reviers et Coat and on hard substrata for Ulva rotundata Bliding. The maximum(More)
Ultrastructural analysis of the gel forming green seaweed sulfated polysaccharide ulvan revealed a spherical-based morphology (10-18 nm diameter) more or less aggregated in aqueous solution. At pH 13 in TBAOH (tetrabutyl ammonium hydroxyde) or NaOH, ulvan formed an open gel-like structure or a continuous film by fusion or coalescence of bead-like(More)