Tsuyoshi Kawano

Nematicidal Alkaloids and Related Compounds Produced by the Fungus Penicillium cf. simplicissimum

A new nematicidal alkaloid, peniprequinolone (1), together with the known alkaloids penigequinolones A and B (2a, 2b), 3-methoxy-4-hydroxy-4-(4′-methoxyphenyl)quinolinone (3), and 3-methoxy-4,6-dihydroxy-4-(4′-methoxyphenyl)quinolinone (4), were isolated from Penicillium cf. simplicissimum (Oudemans) Thom. Cyclopenin (5) and a compound (6a/6b) structurally related to cyclopenin also were isolated from the fungus, and their structures were established by spectroscopic analysis. The biological activities of 1, 2, 3, 4, and 5 were examined by a bioassay with root-lesion nematodes.

βγ-Dehydrocurvularin and Related Compounds as Nematicides of Pratylenchus penetrans from the Fungus Aspergillus sp.

The new nematicidal compound, βγ-dehydrocurvularin (1), together with three known compounds, αβ-dehydrocurvularin (2), 8-β-hydroxy-7-oxocurvularin (3) and 7-oxocurvularin (4), were isolated from the culture filtrate and mycelial mats of Aspergillus sp. The structures of 1-4 were established by spectroscopic methods including 2D NMR. The biological activities of 1-4 were examined by bioassays with root-lesion nematodes, and lettuce and rice seedlings.

Fumiquinones A and B, Nematicidal Quinones Produced by Aspergillus fumigatus

New nematicides named fumiquinones A (1) and B (2), together with spinulosin (3), LL-S490β (4), and pseurotin A (5), were isolated from Aspergillus fumigatus and their structures were established by spectroscopic methods including 2D-NMR. Compound 1 showed effective nematicidal activities against Bursaphelenchus xylophilus and Pratylenchus penetrans without inhibiting plant growth except for lettuce seedlings. Compound 2 showed effective nematicidal activity against B. xylophilus, but had no inhibitory activity against P. penetrans. Compounds 3–5 showed effective nematicidal activities against B. xylophilus without any plant growth inhibition. Compounds 1–5 had no nematicidal activity against Caenorhabditis elegans. This is the first report of the nematicidal activities of compounds 3–5.

BREVICOMPANINES A AND B : NEW PLANT GROWTH REGULATORS PRODUCED BY THE FUNGUS, PENICILLIUM BREVICOMPACTUM

New plant growth regulators, named brevicompanines A 1 and B 2, have been isolated from Penicillium brevicompactum, and their structures have been established by spectroscopic methods including 2D NMR. The biological activities of 1 and 2 have been examined using bioassay methods with lettuce and rice seedlings.

THE LEECH EXCITATORY PEPTIDE, A MEMBER OF THE GGNG PEPTIDE FAMILY : ISOLATION AND COMPARISON WITH THE EARTHWORM GGNG PEPTIDES

A member of the GGNG peptide family was isolated from Hirudo nipponia (leech). GGNG peptides had only been isolated previously from earthworms. The C‐terminus structure of the leech peptide, LEP (leech excitatory peptide), was –Gly–Gly–Asn–amide, while that of the earthworm peptides, EEP (earthworm excitatory peptide), was –Gly–Gly–Asn–Gly. LEP exerted 1000‐fold more potent activities on leech gut than did EEP‐2. On the other hand, EEP‐2 was 1000‐fold more potent than LEP on the crop‐gizzard of the earthworm. Analog peptides of LEP and EEP‐2 were synthesized, and the myoactive potency of each analog on the leech and earthworm tissues was compared.

Pesthetoxin, a New Phytotoxin Produced by the Gray Blight Fungus, Pestalotiopsis theae

Pestalotiopsis theae is known to be a causal fungus for tea gray blight disease. Pesthetoxin was isolated from P. theae as a potent leaf-necrosis substance against tea. The structure of pesthetoxin was established principally by NMR studies to be of four different enolic forms, viz the pairs of internal tautomers (1a)/(1b) and (1c)/(1d) with external tautomerism between them.

Photosynthetic inhibitors in Eucalyptus grandis

Abstract Unlike the G-inhibitors isolated from the leaves of Eucalyptus grandis , synthetic G-inhibitors showed no inhibition of photosynthetic electron transport. These findings indicated that small amounts of impurities present in the natural samples were responsible for the inhibition of photosynthetic electron transport. In support of this, grandinol and homograndinol were isolated from the leaves of E. grandis and were shown to be the active photosynthetic electron transport inhibitory components in the E. grandis preparation of G-inhibitors.

Peniamidienone and penidilamine, plant growth regulators produced by the fungus Penicillium sp. no. 13

Peniamidienone and penidilamine were isolated from cultures of the fungus Penicillium sp. No. 13 as new plant growth regulators and their structures were established by NMR spectroscopic studies. Peniamidienone showed weak inhibition of lettuce seedling growth.

Localization of leech excitatory peptide, a member of the GGNG peptides, in the central nervous system of a leech (Whitmania pigra) by immunohistochemistry and in situ hybridization.

Abstract We have recently isolated a myoactive peptide, called leech excitatory peptide, belonging to the GGNG peptide family from two species of leeches, Hirudo nipponia and Whitmania pigra. Immunohistochemistry and in situ hybridization were employed to localize leech excitatory peptide-like peptide(s) and its gene expression in the central nervous system of W. pigra. A pair of neuronal somata were stained by both immunohistochemistry and in situ hybridization in the supraesophageal, subesophageal, and segmental ganglia. In addition, several other neurons showed positive signals by either immunohistochemistry or in situ hybridization in these ganglia. An immunoreactive fiber was observed to run in the anterior root of segmental ganglion 6, which is known to send axons to the sexual organs, though we failed to detect immunoreactivity in possible target tissues. Antiserum specificity was established by enzyme-linked immunosorbent assay using different leech excitatory peptide-related peptides. Leech excitatory peptide elicited muscular contraction of isolated preparations of penis and intestine at concentrations of 10–8 M. These results suggest that leech excitatory peptide is a neuropeptide modulating neuromuscular transmission in multiple systems, including regulation of reproductive behavior.

An altered method of feeding RNAi that knocks down multiple genes simultaneously in the nematode Caenorhabditis elegans.

In reverse genetics, RNA interference (RNAi) which is substitutable for gene-disruption, is an outstanding method for knockdown of a gene’s function. In Caenorhabditis elegans, feeding RNAi is most convenient, but this RNAi is not suitable for knockdown of multiple genes. Hence, we attempted to establish an efficient method of feeding RNAi for multiple knockdown. We produced bacteria yielding three distinct double-stranded RNAs bound to one another, and fed those bacteria to C. elegans. Quantitative RT-PCR and observation of phenotypes indicated that our method is much more efficient than the traditional one. Our method is useful for investigating genes’ functions in C. elegans.