Proceedings of the Japan Academy, Series B
Online ISSN : 1349-2896
Print ISSN : 0386-2208
ISSN-L : 0386-2208
80 巻, 5 号
選択された号の論文の6件中1~6を表示しています
Reviews
  • Hironori ISHIZAKI
    2004 年 80 巻 5 号 p. 195-203
    発行日: 2004年
    公開日: 2004/09/03
    ジャーナル フリー
    Molecular characterization of the brain secretory peptides, PTTH and bombyxin, of Bombyx mori is reviewed. PTTH is a 30-kDa homodimeric glycoprotein, the monomer of which consists of 109 amino acids. Two monomers are held together by a disulfide bond. cDNA and gene coding for PTTH were cloned and the precursor protein for PTTH monomer was deduced. A novel 5-kD brain secretory peptide named bombyxin has been discovered from Bombyx brain. Bombyxin is highly homologous to vertebrate insulin-family peptides and possesses the prothoracicotropic activity when injected into brain-removed pupae of a heterologous moth, Samia cynthia ricini, though inactive to Bombyx from which it was derived. cDNA and gene coding for bombyxin were cloned, preprobombyxin protein was deduced, and posttranslational processing to generate mature bombyxin was suggested. The Bombyx genome contains highly multiple copies of the gene coding for bombyxins. Immunohistochemically, PTTH- and bombyxin-producing brain neurosecretory cells were identified.


    (Communicated by Saburo TAMURA, M.J.A.)
  • Takayoshi HIGUCHI
    2004 年 80 巻 5 号 p. 204-214
    発行日: 2004年
    公開日: 2004/09/03
    ジャーナル フリー
    Lignin peroxidase (LiP), laccase (LA) and manganese peroxidase (MnP) of white-rot basidiomycetes such as Phanerochaete chrysosporium, Coliorus versicolor, Phlebia radiata and Pleurotus eryngii catalyze oxidative degradation of lignin substructure model compounds and synthetic lignins (DHPs). Side chain- and aromatic ring cleavage products of both phenolic and non-phenolic substrates oxidized by LiP were isolated and characterized by NMR and MS. The cleavage mechanism was elucidated by using 18O, 2H, and 13C labeled lignin substructure dimers with 18O 2 and H218O. Recent studies suggested that LiP is capable of oxidizing lignin directly at the protein surface via a long-range electron transfer process. LA and MnP, which oxidize phenolic but not non-phenolic moieties, generally degrade lignin stepwise from phenolic moieties. However, recent studies indicated that MnP and LA can degrade both phenolic and non-phenolic aromatic moieties of lignin with some special mediators.


    (Communicated by Yasuyuki YAMADA, M.J.A.)
  • Masayuki ISHIKAWA, Yoshimi OKADA
    2004 年 80 巻 5 号 p. 215-224
    発行日: 2004年
    公開日: 2004/09/03
    ジャーナル フリー
    Tobamovirus is a positive-strand RNA virus of plants. Its single-stranded RNA genome replicates via the negative-strand RNA. In this review, we describe our current knowledge about viral and host factors associated with tobamovirus RNA replication and discuss the replication mechanisms. We also mention the usefulness of tobamovirus genomes as vectors.


    (Communicated by Eishiro SHIKATA, M.J.A.)
Original Papers
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