Influence of carboxyl group on the acid hydrolysis of cellulose

Cellulose isolated from wood is more susceptible than cotton cellulose to homogeneous hydrolysis in phosphoric acid. The influence of carboxyl group introduction at the C6 position on the hydrolysis rate of cellulose in 82.5% phosphoric acid was studied as a model of the oxidation of cellulose during pulping. The rate constant of hydrolysis for dissolving pulp was larger than that of cotton cellulose at temperatures of 25°–35°C. Mercerized cotton cellulose was partially oxidized regioselectively at the C6 position by a free radical system using 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO). The oxidized cellulose was obtained at a range of 1.7–12.7 mEq carboxyl content per 100 g of cellulose. The hydrolysis rate of the oxidized cellulose samples accelerated with increasing carboxyl content in the samples.Part of this work was presented at the 5th Annual Meeting of the Cellulose Society of Japan, Kyoto, July 1998     

Analysis of the factors influencing the acetylation rate of wood

Factors influencing the rate of acetylation were examined based on the swelling of wood in the reaction solution and the dimensions of the wood sample. The activation energy of acetylation was also estimated. In a swelling test, it was found that wood swells thoroughly in acetic anhydride even without pyridine above 60°C. Therefore, pyridine may facilitate the acetylation process as a catalyst and not as a swelling agent. The weight gain, x (%), attained at reaction time t (h), for various compositions of acetylation solution or dimensions of wood sample were analyzed by applying an original rate equation [x = a × (1 – e^–kt )^1/n ], where a is the ultimate weight gain (%), k is the rate constant (h^–1), and n is a measure of the hindrance against the diffusion of reagent. The optimum volume fraction of pyridine in the pyridine-catalyzed acetylation was about 0.2. Accompanied by a rise in pyridine content, the reaction showed increased diffusion-controlled behavior. The rate constant, which is not affected by the dimensions of the wood sample, was estimated from which an activation energy of about 130kJ/mol was calculated.     

Adsorptive properties of dyes to cellulosic sheet and discoloration of dye solution by UV-ray irradiation

The adsorptive properties and selectivity of dyes and water molecules to cellulosic sheet, dependence of adsorptive properties of dyes on the concentration of dye solution, and discoloration of the dye solution due to the UV-ray irradiation were determined for 18 kinds of commercial dyes. The results are as follows： 1） the adsorptive properties of dyes to cellulose sheet differed greatly, but did not depend on the dye types such as acidic, basic and so on; 2） adsorptive properties of dyes to cellulosic sheet de- pended on the concentration of dye solution and were classified into 4 types： concentration-independent, increasing or decreasing with dye concentration, and having a maximum. This classification was irrelevant to the dye types; 3） the irradiation of UV-ray did not cause significant discoloration of dye solution itself, which suggested that wood components as well as dye molecules influence the discoloration of wood.     

Analysis of a pair of END+ and END? viruses derived from the same bovine viral diarrhea virus stock reveals the amino acid determinants in Npro responsible for inhibition of type I interferon production

The Exaltation of Newcastle disease virus (END) phenomenon is induced by the inhibition of type I interferon in pestivirus-infected cells in vitro, via proteasomal degradation of cellular interferon regulatory factor (IRF)-3 with the property of the viral autoprotease protein N^pro. Reportedly, the amino acid residues in the zinc-binding TRASH motif of N^pro determine the difference in characteristics between END-phenomenon-positive (END⁺) and END-phenomenon-negative (END⁻) classical swine fever viruses (CSFVs). However, the basic mechanism underlying this function in bovine viral diarrhea virus (BVDV) has not been elucidated from the genomic differences between END⁺ and END⁻ viruses using reverse genetics till date. In the present study, comparison of complete genome sequences of a pair of END⁺ and END⁻ viruses isolated from the same virus stock revealed that there were only four amino acid substitutions (D136G, I2623V, D3148G and D3502Y) between two viruses. Based on these differences, viruses with and without mutations at these positions were generated using reverse genetics. The END assay, measurements of induced type I interferon and IRF-3 detection in cells infected with these viruses revealed that the aspartic acid at position 136 in the zinc-binding TRASH motif of N^pro was required to inhibit the production of type I interferon via the degradation of cellular IRF-3, consistently with CSFV.     

Papillary renal adenoma of distal nephron differentiation in a horse

A 20-year-old thoroughbred mare had a mass in the right kidney. The mass was encapsulated with fibrous capsule and composed of variably-sized papillary projections lined by a single layer of flattened to cuboidal neoplastic epithelial cells with no cytological and nuclear atypia. Immunohistochemically, the neoplastic cells were broadly positive for cytokeratin AE1/AE3 and granular staining for alpha-1-antitrypsin was focally detected; this immunohistochemical property was similar to that of the normal distal nephron. From these results, this case was diagnosed as papillary renal adenoma of distal nephron differentiation.     

Emamectin benzoate as a candidate for a trunk‐injection agent against the pine wood nematode,Bursaphelenchus xylophilus

In order to develop an effective trunk‐injection agent against pine wood nematode, Bursaphelenchus xylophilus, an in vitro assay was used to examine the antinematodal activity of 58 commercially available compounds with known modes of action. Among compounds tested, the GABA receptor agonists had better anti‐nematodal activity than compounds influencing glutamate, N‐methyl‐D ‐aspartate, β‐adrenergic, dopamine, muscarinic acetylcholine and nicotinic acetylcholine receptors, as well as those inhibiting acetylcholinesterase, monoamine oxidase, 5‐hydroxytryptamine uptake and Ca²⁺, K⁺, Na⁺ and Cl⁻ channels. Avermectins and milbemycins strongly inhibited propagation of the nematode. Emamectin benzoate proved to be the most active (IC₉₅ 0.050 µM ) being over 140 times more active than the active ingredient of conventional trunk‐injection agents. It is concluded that emamectin benzoate is a strong candidate for an anti‐nematodal trunk injection agent. © 2000 Society of Chemical Industry     

Potassium acetate-catalyzed acetylation of wood: reaction rates at low temperatures

Spruce wood blocks were acetylated in the presence of potassium acetate (KAc) at 20, 40, 60, 80 and 120°C. At 20°C, the weight percent gain (WPG) due to the KAc-catalyzed acetylation reached 20% in 18 days, whereas that due to pyridine-catalyzed acetylation did not exceed 8%. The hygroscopicity and dimensional stability of the KAc-acetylated wood were the same as those of conventionally acetylated wood at the same WPG, irrespective of reaction temperature. These facts suggest that the KAc enables simplified acetylation of wood at room temperature. The activation energy (E _a) of the KAc-acetylation in the lower temperature range (20–40°C, 121–131 kJ/mol) was comparable to that of the acetylation of wood meal (140–146 kJ/mol). It was speculated that diffusion became a minor factor at reduced reaction rates in the lower temperature range, thus requiring a greater E _a.     

Radial variations of wood properties in <Emphasis Type="Italic">Casuarina equisetifolia</Emphasis> growing in Bangladesh

Radial variations of wood properties (basic density, fiber length, vessel element length, and compression strength) in plantation-grown Casuarina equisetifolia in Bangladesh were investigated for effective utilization of the wood. Samples disks at breast height were randomly collected from trees in a 10-year-old plantation in Cox’s Bazar Forest Division, Bangladesh. The basic density showed a near-constant value up to 30 mm from the pith and then rapidly increased up to 60 mm from the pith. The fiber length and vessel element length gradually increased from the pith to bark. When radial variation of wood properties was determined according to relative distance from the pith, similar radial patterns were observed among the sample trees, indicating that the wood properties in C. equisetifolia may be related to the growth rate. The compression strength parallel to the grain (CS) increased from the pith to bark. A significant positive correlation was found between the air-dried density and the CS. The results obtained indicated that wood around the pith has a relatively low density, and wood outside the pith area has a relatively high density, suggesting that it could be used as structural lumber. Part of this report was presented at the 58th Annual Meeting of Japan Wood Research Society, Tsukuba, March 2008     

Examination of the 16S-23S rRNA intergenic spacer sequences of 'Candidatus Mycoplasma haemobos' and Mycoplasma haemofelis

The intergenic spacer region between the 16S and 23S rRNA genes of mycoplasmas has been used for a genetic marker for identification of the species. Here we show the intergenic spacer regions of two hemotropic mycoplasmas, Mycoplasma haemofelis and 'Candidatus Mycoplasma haemobos (synonym: 'C. M. haemobovis')' are also useful for classification of this particular group of mycoplasms. The spacer region of M. haemofelis and `C. M. haemobos' consisted of 209 and 210 base pairs, respectively, and both lacked the spacer tRNA genes. Phylogenetic analysis suggested a monophyletic relationship among hemoplasmas and M. fastidiosum. A hypothetical secondary structure predicted in the spacer regions tentatively assigned the boxA and boxB motifs peculiar to the members of the genus Mycoplasma. M. haemofelis and 'C. M. haemobos' possessed a stem-loop structure in common, despite the presence of a palindromic nucleotide substitution in the stem region.