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Noda T.,Kumamoto Prefectural Agriculture Research Center | Noda T.,Tokai University | Ono M.,Tokai University | Iimure K.,Kumamoto Prefectural Agriculture Research Center | Araki T.,Tokai University
Bioscience, Biotechnology and Biochemistry | Year: 2010

The conidium of the entomopathogenic fungus, Nomuraea rileyi, has been found to germinate rapidly in the presence of a host insect-derived extract. This extract therefore appears to contain an important factor involved in host recognition by N. rileyi, although the substance (germination-accelerating factor, GAF) responsible for such unique germination behavior has yet to be identified. Our previous study was extended to the isolation of GAF from pupae of the silkworm, a host insect of N. rileyi. This present work subjects GAF to a structural analysis. The chemical structure of GAF is characterized as 2S-amino-tetradeca-4-ene-l, 3R-diol (D-erythro-Cl4-sphingosine) based on spectroscopic data. An examination of the structure-activity relationship shows that the activity of D-erythro-C14-sphingosine was superior to that of sphingosines with shorter and longer carbon chains. It is suggested that the molecular species with a 14-carbon chain of a sphingosine is important for host recognition.


Noda T.,Kumamoto Prefectural Agriculture Research Center | Meguri T.,Daito Fertilizer Co. | Iimure K.,Kumamoto Prefectural Agriculture Research Center | Ono M.,Tokai University | Araki T.,Tokai University
Bioscience, Biotechnology and Biochemistry | Year: 2011

D-ery-Ci4-Sphingosin (Ci4-Sph) was isolated as the germination accelerating factor in Nomuraea rileyi in our previous study. This activity was expected to support fungal infection by reduction of the infection time between conidial adhesion and invasion into the insect. In this study, we estimated the effect of CM-Sph with regard to the infection time. Conidia activated by Ci4-Sph shortened the time to about half, indicating the potential of Ci4-Sph as an adjuvant for fungal pesticide of N. rileyi.


Noda T.,Kumamoto Prefectural Agriculture Research Center | Noda T.,Tokai University | Ono M.,Tokai University | Iimure K.,Kumamoto Prefectural Agriculture Research Center | Araki T.,Tokai University
Bioscience, Biotechnology and Biochemistry | Year: 2010

The conidium of the entomopathogenic fungus Nomuraea rileyi has been found to germinate rapidly in the presence of host insect-derived extracts. Thus the extract appears to contain an important factor involved in host recognition by N. rileyi. However, the substance responsible for such unique germination behavior has yet to be identified. Hence we attempted to purify this substance. One thousand g of dried silkworm pupae was subjected to methanol extraction, followed by methanolysis, two different solvent partitions, and three different column chromatographies. A total of 12.4mg of substance was obtained in the active fraction. The substance obtained exhibited an activity more than 46,000 times higher than that of the methanol extract. The substance was detected as a single peak on Sephadex LH20 column chromatography and as a single band on high-performance thin-layer chromatography. These data indicate that the concentrated fraction contained a high-purity substance.


Noda T.,Kumamoto Prefectural Agriculture Research Center | Noda T.,Tokai University | Satoh T.,Kumamoto Industrial Research Institute | Iimure K.,Kumamoto Prefectural Agriculture Research Center | And 2 more authors.
Bioscience, Biotechnology and Biochemistry | Year: 2011

D-erythro-C14-Sphingosine (C14-Sph) accelerated the germination of Nomuraea rileyi in a solution containing peptone, but activity declined to a large degree in water. This suggests the presence of a co-factor in C14-Sphtriggered germination. Since the main role of peptone is to supply nitrogen constituents, we examined the effects of various nitrogen constituents. It was found that Ala and His were highly effective for C 14-Sph-triggered germination.

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