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Bacterial fruit blotch of cucurbits is a destructive disease caused by Acidovorax avenae subsp. citrulli, which is a typical seedborne pathogen. In seed health testing for this disease, we have detected many strains of Acidovorax with some differences from A. avenae subsp. citrulli. Their 16S rRNA sequences were divided into six types. The most common sequence was completely consistent with that of A. avenae subsp. avenae originally isolated from rice. The other sequences were over 99% similar but not identical to those of A. avenae subsp. avenae and A. avenae subsp. citrulli. Some commercialized antibodies against A. avenae subsp. citrulli reacted with several of these strains. Some of these strains incited yellow spots or brownish water-soaked lesions mainly on young true leaves of cucumber and squash after spray inoculation. Histological observations showed that these strains entered the leaf tissues of cucurbit plants through stomata and multiplied in the intercellular spaces of parenchymatous tissues as well as in the vascular tissues. The amount of bacterial multiplication and spread in the tissues differed among the strains, presumably reflecting their ability to induce symptoms. These isolated strains are therefore different from A. avenae subsp. citrulli, and their potential threat to the cultivation of cucurbits is lower than that of A. avenae subsp. citrulli.

In the Hachirogata reclaimed area, Minamiakita County, Akita Prefecture, Japan, one of the leading agricultural production areas in the country, the agricultural production foundation and facilities are deteriorating significantly, and problems specific to low-lying reclaimed farmland, such as deterioration of water quality and differential settlement of structures, are occurring. This study investigates the effects of salt leaching on the micromechanical behaviour of highly active Hachirogata clay. A leached sample was artificially prepared using a boring sample collected from the Hachirogata reclaimed land, and a micro-indentation test was performed on both non-leached and leached samples. The results of the indentation test confirmed that the electrical conductivity (EC) of Hachirogata clay was highly correlated with cohesion, c, and that the c value dropped sharply when the EC fell below a certain threshold. Therefore, salt leaching leads to a decrease in the cohesion of clay particles by reducing the number of ions in the clay, making the clay easier to deform under load. From the results of this study, it was inferred that localised salt leaching, which changes the micromechanical behaviour of clay, is one of the factors causing ground differential settlement or slip failure. It is expected that such ground problems could be mitigated by identifying locations with low EC values, that is, weak areas in the ground, and implementing countermeasures such as ground improvement or using lightweight embankment materials in those zones.

We investigated the role of the PI3K p85α subunit in the development of acute colitis with a focus on intestinal macrophages. Experimental acute colitis was induced using 3% dextran sulfate sodium (DSS) in drinking water for 7 days. The severity of DSS-induced acute colitis was significantly attenuated in p85α hetero-deficient (p85α+/−) mice compared with WT mice. The expression of proinflammatory mediators in intestinal macrophages isolated from the inflamed colonic mucosa was significantly suppressed in p85α+/− colitis mice compared with WT colitis mice. Interestingly, we found that bone marrow-derived macrophages (BMDMs) from p85α+/− mice produced a significantly higher amount of IL-10 than BMDMs from WT mice. The adoptive transfer of p85α+/− BMDMs, but not WT BMDMs, significantly improved the severity in WT colitis mice, and this effect was reversed by anti-IL-10 antibody. Furthermore, the expression of IL-10 in the intestinal macrophages of p85α+/− normal colonic mucosa was significantly higher than that in the intestinal macrophages of WT normal colonic mucosa. The present results demonstrate that p85α+/− mice exhibit a reduced susceptibility to DSS-induced acute colitis. Our study suggests that a deficiency of PI3K p85α enhances the production of IL-10 in intestinal macrophages, thereby suppressing the development of DSS-induced acute colitis.