It is well known that a silica surface cannot adsorb duplex DNA in common aqueous solution (not chaotropic solution) because of the electrostatic repulsion of the silica surface and polyanionic DNA. However, we recently found that when duplex DNA in phosphoric acid form (or in acidic solution) was used, DNA was successfully adsorbed into mesoporous silicas even in low-salt aqueous solution. The adsorption behaviors of DNA into mesoporous silicas were influenced by the pore diameter sizes. Mesoporous silicas with 2.80- or 3.82-nm peak pore diameters adsorbed DNA the best in diluted NaCl solution. Formation of the hydrogen bond between P(O)OH groups in DNA and adsorbed water, SiOH groups, or both on silica surfaces is regarded as a main factor in this adsorption. The coincidence of the pore sizes and DNA diameter realizes this unique adsorption promoted by the effect of encompassing DNA with the inner surface of mesoporous silica. Although there is no clear direct evidence for including duplex DNA in the mesopores yet, this adsorption technique is expected to provide a new tool for DNA science, because DNA in the pore size 2-5 nm in diameter has to be in unusual disentangled thread form.
A comparative study was carried out on the sugar composition of lipo-polysaccharides (LPS) isolated from representative strains of members of the family Vibrionaceae including all of the constituting genera, i.e., Vibrio, Aeromonas, Photobacterium, Plesiomonas, and Lucibacterium. More than 100 strains were examined. It was found that, with the exception of Vibrio parahaemolyticus 06, 2-keto-3-deoxyoctonate (KDO), known generally as a component sugar in the core region of usual gram-negative bacterial LPS, is virtually absent from LPS of the Vibrio-naceae strains so far examined. Furthermore, mannose was also lacking in LPS of Vibrionaceae strains with the exception of only one strain, A. anaerogenes (ATCC 15467). Instead, some KDO-like substances were found in LPS from Vibrio ("Beneckea H) nereida (ATCC 25917) and Plesiomonas shigelloides including the type strain (ATCC 14029), the same as those found in LPS from V. parahaemolyticus 07 and 012, and three strains of V. alginolyticus. These substances were strongly positive in the periodate-thiobarbituric acid test, yielding a color with maximum absorption at 549 nm. The spectra were identical to that of KDO, whereas substances differed from KDO at least in behavior in high-voltage paper electro-phoresis and thin-layer chromatography. A particularly interesting feature from the chemotaxonomical point of view was found in the sugar composition of LPS isolated from V. cholerae. Fructose was present exclusively in LPS of V. cholerae (both 01 and non-Ol groups and classical and eltor biotypes) with the exception of one strain of Photobacterium phosphoreum (NCMB 844). In addition, a pair of rarely occurring amino sugars, perosamine and quinovosamine, was found in LPS from 0 I group V. cholerae regardless of either the biotype (classical or eltor) or the serotype (Inaba or Ogawa), whereas this pair was not present in non-Ol group V. cholerae (the so-called NAG vibrios). This feature was confirmed with LPS from more than 30 additional strains of 0 I group V. cholerae isolated from patients. The virtual absence of KDO in LPS of the family Vibrionaceae was demonstrated for the first time in this study. These results are compatible with the in-649
[3H] Stevioside was administered orally at a dose of 125mg/kg to Wistar rats, and its disposition and metabolism were studied. The level of radioactivity in the blood increased slowly to a maximum of 4.83pg/ml at 8 hours, exhibiting a biological half-life of 24 hours. At 1 hour, the highest concentration was observed in the small intestine, followed by the stomach and cecum in that order. At 4 hours, the concentration in the cecum was markedly higher than those of other tissues. Radioactivity remaining in the body at 48 hours was 30.7% of the dose. At 120 hours, the percentages of radioactivity excreted into the feces and expired air were 68.4% and 23.9%, respectively, while radioactivity excreted into the urine was only 2.3%. Radioactivity excreted into the bile at 72 hours was 40.9% of the original dose. From the results of biliary and fecal excretion, it was concluded that entero-hepatic circulation occurs in the body. TLC analysis of the intestinal contents, feces and bile showed that stevioside is decomposed by cecal flora to steviol and sugars, indicating that steviol and these sugars are absorbed from the cecum, distributed throughout the whole body, and excreted mainly into feces and expired air.
In Table 2 of the paper, the correct value of SSA of sample G was 872 (m 2 /g), not 87 (m 2 /g).
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