High ambient ammonia promotes growth in a ureogenic goby, Mugilogobius abei

K. Iwata, T. Sakamoto, I. Iwata, E. Nishiguchi, M. Kajimura

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Mugilogobius abei has the ability to produce large amounts of urea when exposed to high ambient ammonia. Despite this metabolically costly approach, and reports of growth inhibition effects of ammonia on fish, M. abei exposed to ammonia shows no adverse effects on growth. To investigate this observation the growth of M. abei was measured at room temperatures for 8 weeks at a constant ration level under solitary and grouped conditions, in 20% SW with or without (control) 2 mM NH4Cl. Furthermore, pituitary mRNA levels of growth hormone, oxygen consumption, incorporation of external 15N-ammonia into amino acid and protein fractions as well as behavioral activities were also examined. The specific growth rates of ammonia-exposed fish under grouped condition over the 8 weeks were significantly higher than those of control, while those rates under solitary condition were not significantly different between the treatments. The pituitary of ammonia-exposed fish had higher growth hormone mRNA than in control fish. The use of 15N isotope revealed that M. abei can actively use external ammonia as a supplementary nitrogen source. Oxygen consumption of ammonia-exposed fish was significantly lower than that of control fish. Locomotor activity and aggressive behavior under grouped condition were significantly reduced in ammonia-exposed fish as compared to those of control. These combined alterations in the ammonia-exposed fish may result in the higher growth rates.

Original languageEnglish
Pages (from-to)395-404
Number of pages10
JournalJournal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
Volume175
Issue number6
DOIs
Publication statusPublished - Aug 1 2005

Keywords

  • Ammonia(N-Ammonia)
  • Growth hormone
  • Growth promotion
  • Mugilogobius abei
  • Reduced aggression

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Biochemistry
  • Physiology
  • Animal Science and Zoology
  • Endocrinology

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