Stress-induced apoptosis in larval embryos of Japanese flounder
T. Yabu, Y. Ishibashi, M. Yamashita-2003
Fisheries
Science, 69(6):
1218-1223
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.
(National Research Institute of Fisheries Science,
Kanazawa, Yokohama 236-8648, Japan, Tel: 81-45-788-7665.
Fax: 81-45-788-5001. Email of M. Yamashita: mic@affrc.go.jp)