To characterize the molecular mechanisms underlying life-stage transitions in Phytophthora infestans, we initiated a chemical genetics approach by screening for a stage-specific inhibitor of morphological development from microbial culture extracts prepared mostly from actinomycetes from soil in Japan. Of the more than 700 extracts, one consistently inhibited Ph. infestans cyst germination. Purification and identification of the active compound by ESI–MS, 1H-NMR, and 13C-NMR identified β-rubromycin as the inhibitor of cyst germination (IC50 = 19.8 μg/L); β-rubromycin did not inhibit growth on rye media, sporangium formation, zoospore release, cyst formation, or appressorium formation in Ph. infestans. Further analyses revealed that β-rubromycin inhibited the germination of cysts and oospores in Pythium aphanidermatum. A chemical genetic approach revealed that β-rubromycin stimulated the expression of RIO kinase-like gene (PITG_04584) by 60-fold in Ph. infestans. Genetic analyses revealed that PITG_04584, which lacks close non-oomycete relatives, was involved in zoosporogenesis, cyst germination, and appressorium formation in Ph. infestans. These data imply that further functional analyses of PITG_04584 may contribute to new methods to suppress diseases caused by oomycetes.

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To utilize a super-hydrophobic tetradecane-adsorbed marshmallow-like gel as a phase-change material (PCM) as a carrier for latent heat transportation by mixing the gel particles with sodium carboxymethyl cellulose (CMC) solution, the dispersion characteristics and flow characteristics of a marshmallow-like gel slurry were investigated. To investigate the dispersion characteristics of the slurry, visual observation of the slurry under static conditions was performed while varying the concentration of CMC, and the apparent dispersion fraction was determined for quantifying dispersion characteristics. The apparent dispersion fraction stabilized within 2 h. At CMC concentrations of < 0.4, 0.6-2, and > 3 wt%, the apparent dispersion fraction increased, remained constant, and reached the complete dispersion state, respectively. At several concentrations, the viscosity of the liquid layer of the gel slurries was lower than that of the pure solution, coinciding with the range where the apparent dispersion fraction increased. Therefore, it was found that the adsorption of CMC onto the surface of marshmallow-like gel affects the dispersion characteristics of marshmallow-like gel slurry. To investigate flow characteristics, friction factor of CMC solution and marshmallow-like gel slurry against Reynolds number was measured. From the results, it was confirmed that the shear-thinning of the CMC solution affected the flow characteristics.

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