Gen Okada

Studies on the distribution of alkalophilic and alkali-tolerant soil fungi I

Soil fungi were isolated from two different soil types using alkaline and slightly acidic media (alkaline cornmeal agar (AC-MA), pH 9.7; cornmeal agar (CMA), pH 6.0) to study their distribution. Different species were obtained on each isolation medium. The number of species ofAcremonium andFusarium increased on ACMA, though many species growing well in acidic conditions were not detected on ACMA. Most of the fungi isolated on ACMA, especially from the alkaline soils, were alkalophiles or alkali-tolerants that can grow at pH 10.Acremonium alternatum, A. furcatum, Acremonium sp. 6,Gliocladium cibotii (YBLF 575),Phialophora geniculata, Stachylidium bicolor andStilbella annulata were alkalophilic, of whichAcremonium sp. 6 was the most pronounced alkalophile. Ability to grow under alkaline conditions, as well as under acidic conditions, was common in manyAcremonium species. The use of alkaline medium facilitates the isolation of alkalophilic soil fungi.

Phylogenetic relationships of the hyphomycete genera Chaetopsina and Kionochaeta based on 18S rDNA sequences

A setiform dematiaceous hyphomycete,Kionochaeta spissa was newly collected and isolated from evergreen broad-leaved forests in the southern parts of Japan. Except for its dematiaceous nature, the species is morphologically similar to a nectriaceous hyphomycete,Chaetopsina fulva. The morphology and cultural properties of the Japanese isolates ofK. spissa were described, and the phylogenetic relationships betweenChaetopsina (C. fulva (type species)) andKionochaeta (K. ramifera (type species),K. spissa andK. ivoriensis) were inferred based on nuclear encoded small subunit (18S) rDNA sequences using the neighbor-joining method.Chaetopsina andKionochaeta were found to be phylogenetically related to the Hypocreales and Sordariales, respectively. Both should be maintained as separate genus for phylogenetic classification. The morphological resemblance especially betweenC. fulva andK. spissa is an example of the convergent evolution.

RK-95113, a New Angiogenesis Inhibitor Produced by Aspergillus fumigatus

We found that the strain Aspergillus fumigatus var. fumigatus RK95-113 produced a new angiogenesis inhibitor, RK-95113. Spectroscopic analyses identified the structure of RK-95113 as a new fumagillin-related small molecule. RK-95113 preferentially inhibited the growth of human umbilical vein endothelial cells (HUVECs) rather than that of human normal fibroblasts in cell proliferation assays and blocked endothlial cell migration induced by vascular endothelial growth factor (VEGF).