Extraction and decomposition of hiba wood into valuable chemicals using stepwise temperature supercritical carbon dioxide treatment

Hiba (Thujopsis dolabrata) wood was treated with supercritical carbon dioxide (scCO₂) at stepwise temperature increments from 50° to 400°C continuously so that extractives (dichloromethane-soluble and -insoluble phases) and solid residues were obtained. The yield of extractives from hiba wood increased with increasing extraction temperature. The volatile compounds in the dichloromethane-soluble phase from scCO₂ extraction at 50°C contained only terpenoids. However, the volatile compounds in the dichloromethane-soluble phase from scCO₂ extraction at 300°C not only contained terpenoids but also phenols, furans, hydrocarbons, and organic acids. The yield of β-thujaplicin, which is a useful compound in hiba wood, increased with increasing extraction temperature from 50°C to 300°C; the optimal conditions for extracting β-thujaplicin were 300°C and 19.61 MPa. Further study of degradated compounds from the cellulosic and lignic materials of hiba wood after stepwise high-temperature scCO₂ treatment above 300°C may provide clues to its efficient use.     

Twenty-three years of stand dynamics in an old-growth Chamaecyparis forest in central Japan

Structures and dynamics of old-growth coniferous stands are affected by several types of disturbances including typhoons. We report the forest dynamics of four old-growth Chamaecyparis stands in central Japan that differ in the disturbance history of typhoons over a period of 23 years. The stem number, basal area and mortality were examined. In a predominant stand of C. obtusa (Sieb. et Zucc.) Endl., 24 % of the C. obtusa canopy trees died, mainly as a result of the severe damage of a strong typhoon that caused a single tree-fall gap and the following gap enlargements. In this stand, the total basal area decreased to 76.5 % of the initial value, although the mortality declined in recent years. In contrast, the other three stands decreased only slightly in the stem numbers (0.0–5.6 %) and increased in the basal areas of C. obtusa canopy trees. It is confirmed that the stand-level ingrowths of 300-year-old C. obtusa canopy trees could contribute to the increase in the stock of each stand. Our results support an idea that the dynamics of old-growth Chamaecyparis forests were greatly affected by typhoons. The stand structures will be gradually changed (with the processes of gap dynamics) and C. obtusa will continue to be dominant, potentially over hundreds of years.     

<Emphasis Type="Italic">Helicobasidium mompa</Emphasis> isolates from sweet potato in continuous monoculture fields

 Isolates of the violet root rot fungus Helicobasidium mompa were collected from herbaceous and tree plants. Their host preference was studied by inoculation experiments using carrots, sweet potatoes, and apple stocks. It was found that sweet potato isolates from Kyushu produced infection cushions on carrots and sweet potatoes but not on apple stocks. Other isolates did not show host preference. Sweet potato isolates were also characterized by ready hyphal mass (sclerotium) production. They were thought to have adapted to the habitat with high disturbance by annual tillage. Received: July 15, 2002 / Accepted: September 26, 2002     

Structural differences between myofibrillar protein,paratropomyosin, and tropomyosin as revealed by high‐performance liquid chromatography

Paratropomyosin (PTM) composes myofibril functions to weaken the rigor linkages formed between actin and myosin during postmortem aging of muscles. PTM has the similar physico‐chemical properties as tropomyosin (TM) that is a regulatory protein of myofibrils. So far, it is unclear whether PTM is definitely different from TM, because the primary structure of PTM has not been determined yet. The aim of this study was to clarify structural difference of PTM from TM. PTM was prepared by column chromatography immediately after slaughter from broiler breast muscle, and purified by high‐performance liquid chromatography (HPLC). Purified PTM was successfully separated from TM, and the recovered PTM molecule was reduced with dithiothreitol to separate again by HPLC. Two subunits were obtained and peptides from each digested subunit by V8 protease were recovered by HPLC, and then amino acid sequences of the peptides were analyzed by protein sequencing. As a result, some amino acid residues were replaced from that of TMα1 isoform which is the major isoform of TM, and also was different between the two subunits. Therefore, it is concluded that PTM clearly differs from TM and it is suggested that functional difference in PTM from TM is attributed to amino acid replacements in subunits composing PTM.     

Osteopetrosis-like disease in a cat with respiratory distress

Magnetic resonance (MR) and computed tomography (CT) were performed in an 8-year-old, spayed female cat with chronic effort respiration at the inspiration phase and stertor. Increased bone opacity in the areas of the head, neck and thorax were observed on radiography. MR images showed no signal intensity on both transverse T1WI and T2WI of the nasal cavity. CT revealed increased bone density and hypertrophy of the nasal turbinate and a narrowed nasal passage. From these results, we concluded this case had osteopetrosis-like disease, and that the respiratory distress was caused by hypertrophy of the nasal turbinate.     

Field evaluation of resistance to kernel infection and mycotoxin accumulation caused by Fusarium head blight in western Japanese wheat (Triticum aestivum L.) cultivars

Fusarium head blight (FHB) remains a serious problem that causes yield and grain quality losses, and mycotoxin accumulation in wheat production in western Japan. A 3-year field trial with artificial FHB inoculation was conducted to evaluate varietal characteristics of FHB resistance among 31 wheat cultivars/lines cultivated in western Japan, including one standard line. Severity of FHB, frequency of Fusarium-damaged kernels (FDK), deoxynivalenol concentration (DON), nivalenol concentration (NIV), and grain yield showed significant differences among years and among cultivars/lines. Interaction between years and cultivars/lines was also significant in these traits, but F values were larger for cultivars/lines than for the interaction. Correlation analysis showed that cultivars/lines with lower FHB severities tended to have lower FDK, DON and NIV, and a higher yield. Resistance to kernel infection (RKI), residuals calculated by regressing FDK against FHB severity, and resistance to mycotoxin accumulation (RTA), residuals calculated by regressing DON + NIV against FDK, also differed significantly among cultivars/lines. These results indicated that varietal differences in response to FHB symptom development, RKI and RTA exist among wheat cultivars/lines in western Japan. Such information is important to aid producers in controlling the disease and for breeders to improve FHB resistance and reduce mycotoxin accumulation in commercial wheat cultivars.     

Genetic dissection of black grain rice by the development of a near isogenic line

Rice (Oryza sativa L.) can produce black grains as well as white. In black rice, the pericarp of the grain accumulates anthocyanin, which has antioxidant activity and is beneficial to human health. We developed a black rice introgression line in the genetic background of Oryza sativa L. ‘Koshihikari’, which is a leading variety in Japan. We used Oryza sativa L. ‘Hong Xie Nuo’ as the donor parent and backcrossed with ‘Koshihikari’ four times, resulting in a near isogenic line (NIL) for black grains. A whole genome survey of the introgression line using DNA markers suggested that three regions, on chromosomes 1, 3 and 4 are associated with black pigmentation. The locus on chromosome 3 has not been identified previously. A mapping analysis with 546 F₂ plants derived from a cross between the black rice NIL and ‘Koshihikari’ was evaluated. The results indicated that all three loci are essential for black pigmentation. We named these loci Kala1, Kala3 and Kala4. The black rice NIL was evaluated for eating quality and general agronomic traits. The eating quality was greatly superior to that of ‘Okunomurasaki’, an existing black rice variety. The isogenicity of the black rice NIL to ‘Koshihikari’ was very high.     

Structure-Activity Relationship and in Vivo Anti-Tumor Evaluations of Dictyoceratin-A and -C,Hypoxia-Selective Growth Inhibitors from Marine Sponge

Oral dictyoceratin-C (1) and A (2), hypoxia-selective growth inhibitors, showed potent in vivo antitumor effects in mice subcutaneously inoculated with sarcoma S180 cells. Structurally modified analogs were synthesized to assess the structure–activity relationship of the natural compounds 1 and 2 isolated from a marine sponge. Biological evaluation of these analogs showed that the exo-olefin and hydroxyl and methyl ester moieties were important for the hypoxia-selective growth inhibitory activities of 1 and 2. Thus far, only substitution of the methyl ester with propargyl amide in 1 was found to be effective for the synthesis of probe molecules for target identification.