Alkaloids from the poisonous plant Ipomoea carnea: effects on intracellular lysosomal glycosidase activities in human lymphoblast cultures

There is natural intoxication of livestock by the ingestion of Ipomoea carnea (Convolvulaceae) in Brazil and other parts of the world. The alkaloidal glycosidase inhibitors swainsonine, 2-epi-lentiginosine, and calystegines B(1), B(2), B(3), and C(1) have been identified as constituents of this plant. Swainsonine is a potent inhibitor of rat lysosomal alpha-mannosidase, with an IC(50) value of 0.02 microM, whereas calystegines B(1), B(2), and C(1) are potent inhibitors of rat lysosomal beta-glucosidase, with IC(50) values of 2.1, 0.75, and 0.84 microM, respectively. The action of swainsonine results in a lysosomal storage disorder that closely mimics alpha-mannosidosis in humans. To determine whether the toxicity of I. carnea to livestock is due to purely swainsonine or due to a combination of effects by swainsonine and calystegines, intracellular lysosomal glycosidase activities in normal human lymphoblasts grown with inhibitors in the medium were examined. Incubation of lymphoblasts with 0.1 microM swainsonine for 3 days resulted in approximately 60% reduction of alpha-mannosidase activity. On the other hand, calystegines B(2) and C(1) showed no inhibition of beta-glucosidase up to 1 mM; instead inclusion of calystegines B(2) and C(1) at 100 microM in the culture medium increased its activity by 1.5- and 1.6-fold, respectively. Calystegines B(2) and C(1) seem to act as chemical chaperones, enhancing correct folding of the enzyme and enabling smooth trafficking to the lysosome. The lysosomal beta-glucosidase inhibitory calystegines seem to have little risk of inducing intoxication of livestock.     

Effects of revision of Japanese food composition tables on estimation of nutrient intakes, with reference to age-dependent differences

OBJECTIVE: To identify effects of revision of the Japanese food composition tables from the fourth version to the fifth version on nutrient intake estimation. DESIGN: A database on 783 samples of 24-hour food duplicate portions was re-visited. Nutrients in the duplicate portions were estimated by use of the fourth and fifth versions of the Japanese food composition tables in parallel, together with supplemental use of other databases. The two sets of estimates were subjected to comparison. SETTING: The sample collection was conducted at 31 sites all over Japan. SUBJECTS: The sample donors were 783 women aged 20-78 years. RESULTS: Compared with the estimates by use of the fourth version of the tables, the estimates by the fifth version were substantially higher for intakes of energy, carbohydrate, dietary fibre, vitamin A and niacin, and lower for iron intake. The increase in carbohydrate intake estimates was more evident in older women than in young women, whereas the decrease in the intake estimation of iron and the increase in that of dietary fibre were more marked in young women than in older women. CONCLUSION: The recent revision of food composition tables in Japan induced substantial changes in the estimation of nutrient intakes, i.e. an increase in energy, carbohydrate, dietary fibre, vitamin A and niacin, and a decrease in iron. The extent of the changes varied depending on age.     

Comparison of the incorporation of oleate and ricinoleate into phosphatidylcholines and acylglycerols in soybean microsomes

The incorporations of oleate (endogenous) and ricinoleate (nonendogenous) into phosphatidylcholine (PC) and acylglycerol (AG) in immature soybean microsomes were compared. [(14)C]Oleate and [(14)C]ricinoleate were incubated individually with soybean microsomal preparations for up to 4 h, and molecular species of PC and AG incorporated were identified and quantified by HPLC. The activities of acyl CoA:lysoPC acyltransferase and phospholipase A(2) are in general not affected by the fatty acid (FA) chain at the sn-1 position. However, comparison between oleate and ricinoleate revealed that different FA incorporated at sn-2 of PC showed some different selection of the molecular species of lysoPC. The incorporation of [(14)C]ricinoleate into triacylglycerols (TAG) was slightly better than that of [(14)C]oleate and indicated that soybean was capable of incorporating ricinoleate into TAG when ricinoleate can be produced endogenously in a transgenic soybean. The incorporation of FA into TAG in soybean microsomes was much slower than that in castor microsomes.     

Molecular diversity of bacterial chitinases in arable soils and the effects of environmental factors on the chitinolytic bacterial community

The molecular diversity of bacterial chitinases in the bulk soils of arable land was investigated using culture-independent methods. The results demonstrate that bacterial chitinases in arable soils are highly diverse and comprise unique groups when their sequences were compared to those in public databases. The diversity of bacterial chitinases in arable soil was further evaluated using conventional phylogenetic analysis, the UniFrac analysis of the phylogenetic data, and the multidimensional scaling (MDS) analysis of T-RFLP profiles to elucidate the relationship between the diversity of bacterial chitinases and soil characteristics. These analyses indicate that environmental factors such as soil type and pH are responsible for shaping the composition of bacterial chitinases.     

Chemical Characteristics in Stemflow of Japanese Cedar in Japan

To clarify the characteristics in stemflow of Japanese cedar (Cryptomeria japonica), we conducted the annual and extensive observation. We examined the chemistry of bulk and wet deposition, throughfall and stemflow at 26 forested sites in June and September 1998. The each sampling site was broadly distributed in all over the Japanese archipelago. The stemflow pH of Japanese cedar was significantly lower (p<0.01) than precipitation and stemflow of broad-leaved species in both months. There were significant anion deficits in stemflow of Japanese cedar, suggesting that organic anions derived from plant sources play an important role in the stemflow acidity. Our results suggested that the strong stemflow acidity in Japanese cedar was derived from an internal biological characteristic rather than influences of external acidic deposition.     

Nutrient Content in Buckwheat Milling Fractions

Buckwheat seeds (Fagopyrum esculentum Moench) were milled into 23 fractions: seven fine flours, three coarse flours, four small semolina, two big semolina, six bran, and one husk fraction. A considerable variation in gross chemical composition was found among the milling fractions. The protein content varied from 4.4 to 11.9% (db) in flours and from 19.2 to 31.3% in bran fractions; starch varied from 91.7 to 70.4% in flours and from 42.6 to 20.3 in bran. The percentage of soluble dietary fiber contained in total dietary fiber was higher in flours than in semolina and bran fractions. Ash, Fe, P, tannin, phytate content, and color were also investigated. A unique distribution of phytate was found in starch. Correlation is significantly positive in husk, bran, and semolina fractions, while correlation is significantly negative in flour fractions. Depending on technological or nutritional demands, appropriate fractions may be chosen to achieve the desired end‐use product.     

Gross nitrification rates in four Japanese forest soils: heterotrophic versus autotrophic and the regulation factors for the nitrification

Measurements of gross NH ₄ ⁺ and NO ₃ ^? production in forest soils were conducted using the ¹⁵N pool dilution method. Mineral topsoils (0?C10?cm depth) were collected from four forests from northern to southern Japan with a natural climate gradient to elucidate the mechanisms regulating gross nitrification rates in forest soils. Additionally, we attempted to evaluate the relative importance of heterotrophic nitrification in gross total nitrification using acetylene as a specific inhibitor of autotrophic nitrification. Distinct differences were found among sites in the gross rates of NH ₄ ⁺ production (3.1?C11.4?mg?N?kg^?1?day^?1) and gross total nitrification (0.0?C6.1?mg?N?kg^?1?day^?1). The rates of gross heterotrophic nitrification were low in this study, indicating that heterotrophic nitrification is of minor importance in most forest mineral topsoils in Japan. Significant relations were found between gross autotrophic nitrification and gross NH ₄ ⁺ production, soil N, and soil C concentrations, but none was found between gross autotrophic nitrification and soil pH. We determined the critical value of the gross NH ₄ ⁺ production rates for gross autotrophic nitrification under which no gross autotrophic nitrification occurred, as well as the critical soil C/N ratio above which gross autotrophic nitrification ceased. Results show that tight coupling of production and consumption of NH ₄ ⁺ prevents autotrophic nitrifiers from utilizing NH ₄ ⁺ as long as NH ₄ ⁺ availability is low.     

Ozonation of a lignin-carbohydrate complex model compound of the benzyl ether type

Evidence for the presence of lignin-carbohydrate bonds of the benzylic ether type in wood and pulps may be obtained by use of ozonation treatment to selectively degrade the lignin. It was found that the benzyl ether bond in 3-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxy-phenoxy)-3-(methyl--d-glucopyranosid-6-O-yl)-1-propanol was rather stable during ozonation in acetic acid-water-methanol 1631 at 0°C. The corresponding acid, 3,4-dihydroxy-2-(methyl--d-glucopyranosid-6-O-yl)-butanoic acid, was found to be the major reaction product. The use of ozonation followed by acid hydrolysis in connection with studies of lignincarbohydrate linkages is briefly discussed.Part of this paper was presented at the 10th ISWPC, Yokohama, 1999     

Seasonal variations in water relations in current-year leaves of evergreen trees with delayed greening

We investigated seasonal patterns of water relations in current-year leaves of three evergreen broad-leaved trees (Ilex pedunculosa Miq., Ligustrum japonicum Thunb., and Eurya japonica Thunb.) with delayed greening in a warm-temperate forest in Japan. We used the pressure-volume method to: (1) assess the extent to which seasonal variation in leaf water relations is attributable to leaf development processes in delayed greening leaves versus seasonal variation in environmental variables; and (2) investigate variation in leaf water relations during the transition from the sapling to the adult tree stage. Leaf mass per unit leaf area was generally lowest just after completion of leaf expansion in May (late spring), and increased gradually throughout the year. Osmotic potential at full turgor (Psi(o) (ft)) and leaf water potential at the turgor loss point (Psi(w) (tlp)) were highest in May, and lowest in midwinter in all species. In response to decreasing air temperature, Psi(o) (ft) dropped at the rate of 0.037 MPa degrees C(-1). Dry-mass-based water content of leaves and the symplastic water fraction of total leaf water content gradually decreased throughout the year in all species. These results indicate that reductions in the symplastic water fraction during leaf development contributed to the passive concentration of solutes in cells and the resulting drop in winter Psi(o) (ft). The ratio of solutes to water volume increased in winter in current-year leaves of L. japonicum and E. japonica, indicating that osmotic adjustment (active accumulation of solutes) also contributed to the drop in winter in Psi(o) (ft). Bulk modulus of elasticity in cell walls fluctuated seasonally, but no general trend was found across species. Over the growing season, Psi(o) (ft) and Psi(w) (tlp) were lower in adult trees than in saplings especially in the case of I. pedunculosa, suggesting that adult-tree leaves are more drought and cold tolerant than sapling leaves. The ontogenetic increase in the stress resistance of I. pedunculosa may be related to its characteristic life form because I. pedunculosa grows taller than the other species studied.     

Surface-check variation in boxed-heart square timber of sugi (Cryptomeria japonica) cultivars dried by the conventional kiln drying

To investigate the factors affecting the surface-check variation in boxed-heart square timber of sugi (Cryptomeria japonica), surface checks formed by the conventional kiln drying were compared for two stem heights of five cultivars with different wood properties. The total length and average length of the surface checks were greater at the upper part of the stems for all the cultivars. This might be caused by more sapwood at the upper part of the stem, and large drying stresses between the outer sapwood and the inner heartwood. The cultivars, in which tangential shrinkage was large owing to small microfibril angle, formed longer surface checks and smaller bow. There was a positive relationship between surface-check length and tangential shrinkage. The heartwood percentage and tangential shrinkage were thought to be important factors affecting the surface-check variation in sugi boxed-heart square timber.