Stress-induced apoptosis in larval embryos of Japanese flounder

Authors

  • Takeshi YABU,

    1. 1 National Research Institute of Fisheries Science, Kanazawa, Yokohama 236-8648,
      2 Department of Aquatic Biosciences, Tokyo University of Marine Science and Technology, Minato, Tokyo 108-8477 and
      3Department of Fisheries, Kinki University, Nara, Nara 631-8505, Japan
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    • a

      Present address: Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan.

  • 1,2a Yasunori ISHIBASHI,

    1. 1 National Research Institute of Fisheries Science, Kanazawa, Yokohama 236-8648,
      2 Department of Aquatic Biosciences, Tokyo University of Marine Science and Technology, Minato, Tokyo 108-8477 and
      3Department of Fisheries, Kinki University, Nara, Nara 631-8505, Japan
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  • and 3 Michiaki YAMASHITA 1,2

    Corresponding author
    1. 1 National Research Institute of Fisheries Science, Kanazawa, Yokohama 236-8648,
      2 Department of Aquatic Biosciences, Tokyo University of Marine Science and Technology, Minato, Tokyo 108-8477 and
      3Department of Fisheries, Kinki University, Nara, Nara 631-8505, Japan
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*Tel: 81-45-788-7665.
Fax: 81-45-788-5001. Email: mic@affrc.go.jp

Abstract

ABSTRACT:  Stress-induced apoptosis was characterized in larval embryos of Japanese flounder using a caspase-3-like activity assay and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining of whole mounts. Severe stress conditions, such as heat shock by temperature shift from 16°C to 28°C or 29°C for 1 h, and ultraviolet (UV) irradiation at 20–100 mJ/cm2, induced extensive apoptosis in embryos. Following the induction of stress, many TUNEL-positive apoptotic cells were found in the yolk sac, heart, and larval fin. Caspase-3-like activity against a fluorogenic substrate, acetyl-Asp-Glu-Val-Asp-α-4-methylcoumaryl-7-amide, increased in a dose-dependent manner during stress-induced apoptosis. In addition, C2-ceramide treatment (5–10 µM) induced a similar apoptosis pattern to stress treatment. These findings indicate that a pro-apoptotic pathway, which is caspase-3 mediated and acts through ceramide signaling, plays a major role in induction of apoptosis under stress conditions.

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