Staff

Professor : Miyagawa, Hisashi, Dr. Agric. Sci.

Associate Professor : Nakagawa, Yoshiaki, Dr. Agric. Sci.

Assistant Professor : Miyashita, Masahiro, Dr. Agric. Sci


Students and research fellows

Doctor's program :  (1)      
Master's program :  (4)
Undergraduate   :   (4)

Research Activities (2007.4-2008.3)

a) Metabolism of Plant Hormone Auxin

Indole-3-acetic acid (IAA) is a plant hormone auxin that plays an important regulatory role in plant growth and development. In order to elucidate the species differences in the metabolic pathways of IAA among gramineous plants, IAA metabolite profile in maize was compared with that of rice. Quantitative analysis of metabolites using LC-MS/MS showed that IAA mainly underwent successive oxidation at C-2 and C-7 of IAA, followed by the glucosylation at the resulting 7-hydroxy group in maize seedlings. Major metabolites in rice seedlings such as N-glucosyl IAA and its aspartate- and glutamate-conjugates were detected only in a trace amount, giving contrast between the metabolite profiles in these two plants.

b) Structure-Activity Relationships of Ecdysone Agonists

Insect molting is regulated by a steroidal hormone, 20-hydroxyecdysone in vivo. In plants a number of ecdysone agonists are identified, and ponasterone A is known as the most potent ecdysone agonist. Ponasterone A analogs with various steroid moiety were chemically synthesized and their binding activity to ecdysone receptor of Drosophila cells (Kc cells) was measured. Introduction of functional groups such as hydroxyl and oxo groups to A and B-rings of steroid enhanced the ligando-receptor binding. Non steroidal ecdysone agonists such as N-benzoyl tetrahydroquinoline and oxazoline-type analogs were chemically synthesized and their binding acyivity to Lepidoptera and Diptera ecdysone receptors.

c) Chemistry of bioactive peptides.

i) Plants induce various defense responses when they are attacked by pathogens. These defense responses are triggered by a variety of molecules (elicitors). In order to search for new elicitors, random hexapeptide libraries were prepared using a technique of combinatorial chemistry, and the active compounds were screened by an assay based on the response in cultured tobacco cells. Consequently, active peptides,YGIHTH, were obtained. Structure-activity relationship study showed that the N-terminal 4 residues were essential for the activity.
ii) An insecticidal peptide was isolated from the venom of the Japanese scorpion Isometrusmaculatus, and its amino acid sequence was determined by Edman degradation of the intact and fragment peptides obtained by partial enzymatic digestion. Since deduced amino acid sequence had homology with the antimicrobial scorpion toxins, the antimicrobial activity of the peptides was examined. As a result, the peptide showed the significant antimicrobial activity in addition to the insect toxicity.

Publications

Review papers

Nakagawa, Y.
Molting hormone analogs, In Hormone Handbook. eBook. Nankoudou, III-B-7-b, 2007 [in Japanese]
Nakagawa, Y.: Structure-activity relationship and mode of action study of insect growth regulators. J Pestic Sci 32, 143-150 [in Japanese] 2007

Nakagawa, Y., and H. Miyagawa
New Insecticides in "Shokubutsu-wo-mamoru", 123-150, 2008


Original papers

Dubouzet, J. G., A. Ishihara, F. Matsuda, H. Miyagawa, H. Iwata, and K. Wakasa
Integrated metabolomic and transcriptomic analyses of high-tryptophan rice expressing a mutant anthranilate synthase alpha subunit, J Exp Bot 58; 3309-3321, 2007

Ishihara, A., F. Matsuda, H. Miyagawa and K. Wakasa
Metabolomics for metabolically manipulated plants: effects of tryptophan overproduction, Metabolomics, 3; 319-334, 2007

Kai, K., S. Nakamura, K. Wakasa and H. Miyagawa
Facile Preparation of Deuterium-Labeled Standards of Indole-3-Acetic Acid (IAA) and Its Metabolites to Quantitatively Analyze the Disposition of Exogenous IAA in Arabidopsis thaliana, Biosci Biotechnol Biochem 71; 1946-1954, 2007

Kai, K., K. Wakasa and H. Miyagawa
Metabolism of indole-3-acetic acid in rice: Identification and characterization of N-beta-d-glucopyranosyl indole-3-acetic acid and its conjugates, Phytochemistry. 68; 2512-2522, 2007

Kai, K., J. Horita, K. Wakasa and H. Miyagawa
Three oxidative metabolites of indole-3-acetic acid from Arabidopsis thaliana, Phytochemistry 68; 1651-1663, 2007

Matsuda, F., K. Wakasa and H. Miyagawa
Metabolic flux analysis in plants using dynamic labeling technique: Application to tryptophan biosynthesis in cultured rice cells, Phytochemistry 68; 2290-2301, 2007

Matsushita, N., M. Miyashita, A. Sakai, Y. Nakagawa and H. Miyagawa
Purification and characterization of a novel short-chain insecticidal toxin with two disulfide bridges from the venom of the scorpion Liocheles australasiae. Toxicon 50; 861-867, 2007

Minakuchi, C., T. Ogura, H. Miyagawa and Y. Nakagawa.
Effects of the structures of ecdysone receptor (EcR) and ultraspiracle (USP) on the ligand-binding activity of the EcR/USP heterodimer. J Pest Sci 32; 379-384, 2007

Miyashita, M., J. Otsuki, Y. Hanai, Y. Nakagawa and H. Miyagawa
Characterization of peptide components in the venom of the scorpion Liocheles australasiae (Hemiscorpiidae). Toxicon 50; 428-437, 2007

Nakagawa, Y., A. Sakai, F. Magata, T. Ogura, M. Miyashita and H. Miyagawa
Molecular cloning of the ecdysone receptor and the retinoid X receptor from the scorpion Liocheles australasiae. FEBS J 274; 6191-6203, 2007

Tamaki, H., A. Shimada, Y. Ito, M. Ohya, J. Takase, M. Miyashita, M. Miyagawa, H. Nozaki, R. Nakayama and H. Kumagai
LPT1 encodes a membrane-bound O-acyltransferase involved in the acylation of lysophospholipids in the yeast Saccharomyces cerevisiae, J Biol Chem 282, 34288-34298; 2007


Proceedings and Reports

Nakagawa, Y.
Structure-activity relationship and mode of action study of insect growth regulators. J Pestic Sci 32, 135-136.

Miyagawa, H., and Ueyama, I.,
Summary of Scientific Programs in 11th IUPAC International Congress of Pesticide Chemistry, in Pesticide Chemsitry, Ohkawa, H., Miyagawa, H., and Lee, P. W., Eds., Wiley-VCH, Weinheim, pp. 459-478, 2007