Changes in tissue thyroxine level of metamorphosing Japanese flounder Paralichthys olivaceus reared at different temperatures.

1 January 1989

journal article
Published by Japanese Society of Fisheries Science in NIPPON SUISAN GAKKAISHI

Vol. 55 (3) , 485-490
https://doi.org/10.2331/suisan.55.485

Abstract

Effects of thyroid hormones and rearing temperature on Japanese flounder metamorphosis were studied by measuring tissue concentration of thyroxine (T₄) by radioimmunoassay. Larvae reared at 15 or 22°C of various developmental stages were quickly frozen and stored at about -32°C until assayed. Non-detectable values of T₄ were obtained for pre-metamorphic larvae at both 15 and 22°C. The T₄ level increased to a maximum of 16.2ng/g during late metamorphosis, and then decreased slightly. Higher rearing temperature accelerated growth and metamorphosis and also induced earlier increase in tissue T₄ levels. Comparison of larvae of similar developmental stages reared in different temperatures revealed no significant difference in T₄ levels. These results indicate that thyroid hormones play an important role in Japanese flounder metamorphosis.

Keywords

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