Age-dependent in situ hepatic and gill CYP1A activity in the see-through medaka (Oryzias latipes).

Journal Article (Journal Article)

We used a recently introduced strain of medaka, the see-through medaka, whose internal organs can be seen through the skin, to develop an in situ toxicity assay of ethoxyresorufin-O-deethylase (EROD) activity that detected fluorescence from resorufin, a metabolite of ethoxyresorufin and thus an indicator of CYP1A activity. EROD activity in the liver and gills of 2-week post-hatch see-through medaka exposed simultaneously to various concentrations of 3-methylcholanthrene and 200 microg/L ethoxyresorufin for 24 h was proportional to the 3-methylcholanthrene dose. Activities in the liver and gills peaked at 40 microg/L of 3-methylcholanthrene and then decreased at higher doses, possibly because of 3-methylcholanthrene toxicity. At 1-week post-hatch stage, however, constant high EROD activity was observed in controls and at all 3-methylcholanthrene doses. Four-week post-hatch see-through medaka exhibited less EROD activity than 2-week post-hatch see-through medaka, and activity in the liver peaked at 100 microg/L of 3-methylcholanthrene. Adult see-through medaka were not suitable for fluorescence detection owing to their thick skin, muscle and/or tissue. In tests of oxidative activity response to ethoxyresorufin, 1-day and 1-week post-hatch see-through medaka exhibited high intrinsic EROD activity in the liver, gills, and other organs in the absence of 3-methylcholanthrene. This intrinsic activity declined with growth and explained the high constant EROD activity at 1-week post-hatch stage.

Full Text

Duke Authors

Cited Authors

  • Kashiwada, S; Goka, K; Shiraishi, H; Arizono, K; Ozato, K; Wakamatsu, Y; Hinton, DE

Published Date

  • February 2007

Published In

Volume / Issue

  • 145 / 1

Start / End Page

  • 96 - 102

PubMed ID

  • 16914386

International Standard Serial Number (ISSN)

  • 1532-0456

Digital Object Identifier (DOI)

  • 10.1016/j.cbpc.2006.07.005


  • eng