Physiological Function and Metabolism of Free D-Alanine in Aquatic Animals

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Abstract

Aquatic crustaceans and some bivalve mollusks contain a large amount of free <small>D</small>-alanine (up to 100 μmol/g wet wt.) in their tissues. Under high salinity stress, crustaceans and bivalve mollusks largely accumulate <small>D</small>- and <small>L</small>-alanine irrespective of species examined, together with <small>L</small>-glutamine, <small>L</small>-proline, and glycine of which increases are species dependent. These data indicate that <small>D</small>-alanine is one of the major compatible osmolytes responsible for the intracellular isosmotic regulation in the tissues of crustaceans and bivalves. Alanine racemase has been proven to catalyze the interconversion of <small>D</small>- and <small>L</small>-alanine in these invertebrates. The enzyme has been isolated to homogeneity from the muscle of black tiger prawn <i>Penaeus monodon</i> and its cDNA has been cloned from the muscle and hepatopancreas of kuruma prawn <i>Penaeus japonicus</i> for the first time in eukaryotes other than yeast. Several fish species fed on crustaceans and mollusks contain <small>D</small>-amino acid and <small>D</small>-aspartate oxidases that catalyze the decomposition of <small>D</small>-amino acids. A cDNA of <small>D</small>-amino acid oxidase has been cloned from the hepatopancreas of omnivorous common carp <i>Cyprinus carpio</i>. During oral administration of free <small>D</small>-alanine to carp, the activity and mRNA of <small>D</small>-amino acid oxidase increased rapidly in hepatopancreas and the increases were highest in intestine followed by hepatopancreas and kidney. These data suggest that <small>D</small>-amino acid oxidase is inducible in carp and an important enzyme responsible for the efficient utilization of carbon skeleton of <small>D</small>-alanine in their feeds.

Journal

  • Biological and Pharmaceutical Bulletin

    Biological and Pharmaceutical Bulletin 28(9), 1571-1577, 2005

    The Pharmaceutical Society of Japan

Cited by:  4

Codes

  • NII Article ID (NAID)
    110003666470
  • NII NACSIS-CAT ID (NCID)
    AA10885497
  • Text Lang
    ENG
  • Article Type
    Journal Article
  • ISSN
    0918-6158
  • NDL Article ID
    7409327
  • NDL Source Classification
    ZS51(科学技術--薬学)
  • NDL Call No.
    Z53-V41
  • Data Source
    CJPref  NDL  NII-ELS  J-STAGE 
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