Estimation and comparison of nitrogen loads and attenuation in agricultural catchments of Japan and Korea.

To help in clarifying the relationship between the time lag and attenuation of nitrogen (N) loads generated in agricultural catchments, long-term trends in activities that generate N loads and in environmental N loads were estimated in catchments in Japan and Korea dominated by non-point-source emissions. Our approach used statistical data and geographical information system software to analyze pollutant loads. The method was successful in both countries because of the availability of well-developed statistics, geographical information, and weather and water quality monitoring systems, and the accumulation of research data concerning the generation of N loads and the fate of N in soils. Comparison of environmental loads with the loads observed in river water at the outlet of each catchment revealed that: (1) the effect of changes in the environmental load in a catchment appeared almost immediately in the river water quality in Korea, but did not appear clearly even 10 years later in Japan; and (2) the strength of the attenuation appeared to be much lower in Korea than in Japan. These findings suggest that regional characteristics play important roles in the sensitivity of water quality to load-generating activities.

Polysaccharides in fungi. XXXVIII. Anti-diabetic activity and structural feature of a galactomannan elaborated by Pestalotiopsis species.

A fungus of Pestalotiopsis species produced an extracellular, water-soluble polysaccharide (PS-N). PS-N exhibited significant hypoglycemic activity in streptozotocin-induced diabetic mice following intraperitoneal administration and had an effect on oral glucose tolerance in normal mice following oral administration. PS-N ([alpha]D +34.5 degrees in water) was homogeneous on gel chromatography, it is composed of galactose and mannose in a molar ratio of 1:9, and its molecular weight was estimated by gel chromatography to be about 24,000. Its structure was investigated by a combination of chemical and spectroscopic methods. The results indicated that PS-N, a highly branched galactomannan, is composed of beta-(1-->3)-linked D-galactofuranosyl and non-reducing terminal beta-D-galactofuranosyl residues, in addition to alpha-D-mannopyranosyl residues of a yeast mannan type.

A mutant allele skt5 affecting protoplast regeneration and killer toxin resistance has double mutations in its wild-type structural gene in Saccharomyces cerevisiae.

Saccharomyces cerevisiae strains carrying the mutant allele skt5 are resistant to the killer toxin of Kluyveromyces lactis and are defective in protoplast regeneration. The DNA sequence analysis of the cloned mutant skt5 gene showed a nucleotide substitution (causing a glycine-to-glutamic acid substitution) and also a nucleotide insertion (causing a frameshift at the extreme carboxyterminal region) in the structural region from its wild-type gene.