Herbicide discharge from rice paddy fields by surface runoff and percolation flow: A case study in paddy fields in the Lake Biwa basin, Japan.

The transport of three herbicides, pyriminobac-methyl, imazosulfuron and pyraclonil from a watershed that includes 40 ha of paddy fields to a drainage canal was monitored in the Lake Biwa basin, Japan. Based on the intensive monitoring of all paddy plots and in the drainage canal conducted on 3 days during and after the application period, the passage of herbicide discharge from the paddy fields to the drainage canal was separated into surface runoff obtained from field observations and percolation flow calculated from the herbicide mass balance. Surface runoff from paddy plots immediately after herbicide application, discharging a large volume of paddy water, or both processes in conjunction had a significant effect on herbicide discharge. Without surface runoff, paddy fields discharged a consistently high amount of herbicide gradually by percolation flow. These results suggest that considerable amounts of herbicides were discharged into the drainage canal through percolation even if appropriate water management to prevent herbicide surface runoff was practiced.

The effect of passages during Japanese BCG vaccine production on genetic stability and protective efficacy.

Many genetic differences have been found among currently available BCG vaccines. To avoid continued accumulation of phenotypic or genotypic changes in the strains, WHO and most national regulatory authorities request that the vaccine should not be prepared by more than 12 passages from the master seed lot. However, it has recently been reported that genetic changes occur even during the passage for vaccine production. In this study, the genetic stability of Japanese BCG vaccine production using currently available PCR methods and protective efficacy using a guinea-pig model during the passages were examined. The results showed that there were no significant differences between the seed lot, the product manufactured by normal procedures, and the 20th passage product. These results indicate that the maximum number of passages as currently required by WHO for BCG vaccine production is adequate for the Japanese vaccine, and that new genetic tools may help to examine the quality control of the BCG vaccine.

Changes in the gene expression of the white rot fungus Phanerochaete chrysosporium due to the addition of atropine.

We constructed a LongSAGE (Long Serial Analysis of Gene Expression) library from a 3-d culture of Phanerochaete chrysosporium supplemented with atropine, which inhibits the production of lignin-degrading enzymes. The library (the atropine library) contains 13,108 LongSAGE tags and 6,783 unique tags. The gene expression profile represented by the tags was compared with those of two previously constructed libraries, one of which was constructed using 2-d cultures in which the fungus had not yet produced ligninolytic enzymes (the 2-d library) and the other was constructed using 3-d cultures in which the fungus had just started to produce the enzymes (the 3-d library). We found a total of 595 genes that were at least twice more highly or at least twice less highly expressed in the 3-d library than in the 2-d library or the atropine library, and the fluctuations were statistically significant. The relationships among these 595 genes were considered using cluster analysis. Of the 595 genes, 164 showed expression patterns similar to those of four ligninolytic enzyme genes, which were more expressed on day 3 than under any other conditions. Many of these 164 genes comprised genes possibly involved in lignin degradation, lipid metabolism, xenobiotic degradation, stress response, or signal transduction pathways.