Takashi Adachi

Isolation and characterization of alginate-derived oligosaccharides with root growth-promoting activities

Lytic digestion of poly(mannuronate), poly(guluronate), and alginate with an alginate lyase from Alteromonas macleodii was used to prepare mixtures of unsaturated oligosaccharides. Four oligosaccharides isolated from the alginate lyase-lysate by anion-exchange chromatography on Q-Sepharose were found to be the major components of the root growth-promoting lysate. The oligosaccharides were analyzed by NMR and SIMS and identified as di- and tri-saccharides having O-(4-deoxy-L-erythro-hex-4-enopyranosyluronic acid)-1--> at the nonreducing terminus. The trisaccharides from the lysate were found to have root growth-promoting activity in a barley bioassay.

Comparison of the nutritional effects of fructo-oligosaccharides of different sugar chain length in rats

Abstract The influence of fructo-oligosaccharides of different sugar chain length on growth, nitrogen balance, and mineral balance was examined in rats fed diets containing either sucrose, 1-kestose, nystose, or a mixture of these at 50 or 100 g/kg of diet. Rats were fed the experimental diets for six weeks, and nitrogen balance and mineral (Ca and Mg) balance were examined after the second and fourth week. Food intake and body weight gain did not differ significantly among the groups. Each fructo-oligosaccharide fed was found to increase Ca and Mg absorption dose-dependently during the first balance study period and the degrees of increase in Ca and Mg absorption were similar with each fructo-oligosaccharide fed regardless of the level present in the experimental diet. Also, each of the fructo-oligosaccharides was found to increase fecal excretion of nitrogen, but there was no clear dose-dependence and the extent of increase in fecal excretion of nitrogen was similar for each fructo-oligosaccharide fed. In conclusion, our findings demonstrate that ingestion of fructo-oligosaccharides leads to increases in Ca and Mg absorption and an increase in fecal excretion of nitrogen, however, differences in sugar chain length do not influence their nutritional effects considerably in rats.

Introduction of a 50 kbp DNA Fragment into the Plastid Genome

Plastid transformation technology has been used for the analysis and improvement of plastid metabolism. To create a transplastomic plant with a complicated and massive metabolic pathway, it is necessary to introduce a large amount of DNA into the plastid. However, to our knowledge, the largest DNA fragment introduced into a plastid genome was only 7 kbp long and consisted of just three genes. Here we report the introduction of foreign DNA of 23–50 kbp into the tobacco plastid genome with a bacterial artificial chromosome (BAC)-based plastid transformation vector. It was confirmed that the introduced DNA was passed on to the next generation. This is the first description of plastid transformation with a large amount of foreign DNA.

Enzymatic synthesis of novel branched sugar alcohols mediated by the transglycosylation reaction of pullulan-hydrolyzing amylase II (TVA II) cloned from Thermoactinomyces vulgaris R-47

Transglycosylation reactions are useful for preserving a specific sugar structure during the synthesis of branched oligosaccharides. We have previously reported a panosyl unit transglycosylation reaction by pullulan-hydrolyzing amylase II (TVA II) cloned from Thermoactinomyces vulgaris R-47 (Tonozuka et al., Carbohydr. Res., 1994, 261, 157-162). The acceptor specificity of the TVA II transglycosylation reaction was investigated using pullulan as the donor and sugar alcohols as the acceptor. TVA II transferred the α-panosyl unit to the C-1 hydroxyl group of meso-erythritol, C-1 and C-2 of xylitol, and C-1 and C-6 of d-sorbitol. TVA II differentiated between the sugar alcohols hydroxyl groups to produce five novel non-reducing branched oligosaccharides, 1-O-α-panosylerythritol, 1-O-α-panosylxylitol, 2-O-α-panosylxylitol, 1-O-α-panosylsorbitol, and 6-O-α-panosylsorbitol. The Trp(356)→Ala mutant showed similar transglycosylation reactions; however, panose production by the mutant was 4.0-4.5-fold higher than that of the wild type. This suggests that Trp(356) is important for recognizing both water and the acceptor molecules in the transglycosylation and the hydrolysis reaction.