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Papers by Daniela Pacoda
Phytochemistry, 1997
D-[U-'4C]Glucosamine was rapidly taken up by oat coleoptile segments and metabolized to radioacti... more D-[U-'4C]Glucosamine was rapidly taken up by oat coleoptile segments and metabolized to radioactive UDP-N-acetylglucosamine, which acted as specific glycosyl donor for the synthesis of glycolipids and cytosolic, membrane-bound and cell-wall glycoproteins. Cell-wall glycoproteins were solubilized from the walls by either cell-wall-degrading enzymes or chemical extractants. The solubilized cell-wall glycoproteins in the presence of peptide N-glycosidase F released oligosaccharide chains higher than seven glycosidic residues. The combined action of peptide N-glycosidase F and N-acetyl-fi-D-glucosaminidase on cell-wall glycoproteins indicated the presence of N-acetylglucosamine residues fi-1,2-linked to mannose. Less than 9% of the radioactive oligosaccharide chains was released from the solubilized cell-wall glycoproteins when treated with 0.5 M NaOH at 20", whereas more than 45% of the radioactivity was released in the presence of 1 M NaOH at 50". The high hydrolytic sensitivity of cell-wall glycoproteins to peptide N-glycosidase F, N-acetyl-B-Dglucosaminidase and NaOH at 50" indicated that most N-acetylglucosamine residues were incorporated into N-linked cell-wall glycoproteins.
Journal of Plant Physiology, 2004
The effects of hydrogen peroxide (H2O2), nitric oxide (NO), and a combination of both on the meta... more The effects of hydrogen peroxide (H2O2), nitric oxide (NO), and a combination of both on the metabolism of cell wall polysaccharides were studied in tobacco (Nicotiana tabacum L.) cv Bright Yellow 2 (BY-2) suspension cultured cells in the presence of D-[U-14C]glucose or D-[U-14C]galactose as radioactive tracers. We found that the radiolabelling of newly synthesised total cell wall polysaccharides (pectins, hemicelluloses and alpha-cellulose), buffer-soluble polysaccharides, and membrane-associated polysaccharides decreased under the influence of exogenous systems generating H2O2 and NO. However, when the total amount of newly synthesised cell wall polysaccharides was calculated as a percentage of the total cellular radioactivity (ethanol-soluble pool plus the homogenate of ethanol-insoluble material), all treatments showed negligible effects in the presence of D-[U-14C]glucose or D-[U-14C]galactose as tracers. This occurred because the treatments generating H2O2, NO and H2O2 plus NO caused a marked decrease in the concentration of the ethanol-soluble pool as well as in the total radioactivity found in the homogenate of the ethanol-insoluble material. Most of the radioactivity taken up by the cells was evolved as 14CO2 during the respiratory processes. A qualitative and quantitative characterisation of the ethanol-soluble pool showed that radioactive UDP-sugars in BY-2 suspension cultured cells were differentially reduced by all treatments. Therefore, the decrease of the newly synthesised cell wall polysaccharides seems to be strictly dependent on the reduction of the UDP-sugars pool.
Plant Physiology and Biochemistry, 1999
The effect of brefeldin A (BFA) on the synthesis and incorporation of polysaccharides, proteins a... more The effect of brefeldin A (BFA) on the synthesis and incorporation of polysaccharides, proteins and glycoproteins into the cell wall of subapical coleoptile segments isolated from etiolated oat seedlings (Avena sativa L. cv. Angelica) has been investigated. In the presence of D-[U-14C]-glucose, the incorporation of radioactive glycosyl residues into buffer-soluble, membrane (matrix polysaccharides) and cell wall polysaccharides was drastically inhibited
Phytochemistry, 1997
D-[U-'4C]Glucosamine was rapidly taken up by oat coleoptile segments and metabolized to radioacti... more D-[U-'4C]Glucosamine was rapidly taken up by oat coleoptile segments and metabolized to radioactive UDP-N-acetylglucosamine, which acted as specific glycosyl donor for the synthesis of glycolipids and cytosolic, membrane-bound and cell-wall glycoproteins. Cell-wall glycoproteins were solubilized from the walls by either cell-wall-degrading enzymes or chemical extractants. The solubilized cell-wall glycoproteins in the presence of peptide N-glycosidase F released oligosaccharide chains higher than seven glycosidic residues. The combined action of peptide N-glycosidase F and N-acetyl-fi-D-glucosaminidase on cell-wall glycoproteins indicated the presence of N-acetylglucosamine residues fi-1,2-linked to mannose. Less than 9% of the radioactive oligosaccharide chains was released from the solubilized cell-wall glycoproteins when treated with 0.5 M NaOH at 20", whereas more than 45% of the radioactivity was released in the presence of 1 M NaOH at 50". The high hydrolytic sensitivity of cell-wall glycoproteins to peptide N-glycosidase F, N-acetyl-B-Dglucosaminidase and NaOH at 50" indicated that most N-acetylglucosamine residues were incorporated into N-linked cell-wall glycoproteins.
Journal of Plant Physiology, 2004
The effects of hydrogen peroxide (H2O2), nitric oxide (NO), and a combination of both on the meta... more The effects of hydrogen peroxide (H2O2), nitric oxide (NO), and a combination of both on the metabolism of cell wall polysaccharides were studied in tobacco (Nicotiana tabacum L.) cv Bright Yellow 2 (BY-2) suspension cultured cells in the presence of D-[U-14C]glucose or D-[U-14C]galactose as radioactive tracers. We found that the radiolabelling of newly synthesised total cell wall polysaccharides (pectins, hemicelluloses and alpha-cellulose), buffer-soluble polysaccharides, and membrane-associated polysaccharides decreased under the influence of exogenous systems generating H2O2 and NO. However, when the total amount of newly synthesised cell wall polysaccharides was calculated as a percentage of the total cellular radioactivity (ethanol-soluble pool plus the homogenate of ethanol-insoluble material), all treatments showed negligible effects in the presence of D-[U-14C]glucose or D-[U-14C]galactose as tracers. This occurred because the treatments generating H2O2, NO and H2O2 plus NO caused a marked decrease in the concentration of the ethanol-soluble pool as well as in the total radioactivity found in the homogenate of the ethanol-insoluble material. Most of the radioactivity taken up by the cells was evolved as 14CO2 during the respiratory processes. A qualitative and quantitative characterisation of the ethanol-soluble pool showed that radioactive UDP-sugars in BY-2 suspension cultured cells were differentially reduced by all treatments. Therefore, the decrease of the newly synthesised cell wall polysaccharides seems to be strictly dependent on the reduction of the UDP-sugars pool.
Plant Physiology and Biochemistry, 1999
The effect of brefeldin A (BFA) on the synthesis and incorporation of polysaccharides, proteins a... more The effect of brefeldin A (BFA) on the synthesis and incorporation of polysaccharides, proteins and glycoproteins into the cell wall of subapical coleoptile segments isolated from etiolated oat seedlings (Avena sativa L. cv. Angelica) has been investigated. In the presence of D-[U-14C]-glucose, the incorporation of radioactive glycosyl residues into buffer-soluble, membrane (matrix polysaccharides) and cell wall polysaccharides was drastically inhibited