銅処理したウナギの血液における食菌作用の低下

Lowered Phagocytosis in the Blood of Eels Exposed to Copper

Mushiake Keiichi

Nakai Toshihiro

Muroga Kiyokuni

魚病研究

In a previous paper, the authors reported that the susceptibilities of Japanese eel (Anguilla japonica) to Edwardsiella tarda and Pseudomonas anguilliseptica were increased by exposure to sublethal concentrations of copper (100 or 250 μg-Cu/l) for 24 or 48 hours, and this was interpreted as a tertiary response to stress. In the present study, primary and secondary responses to stress caused by copper exposure were investigated.

The apparent increase of corticosteroids was observed in eels exposed to copper for 12 hours. The numbers of lymphocytes and granulocytes in the 24 hour-exposed eels decreased to one third of those of control fish. It was also demonstrated by an in vitro test that phagocytic rate of leucocytes in the blood of the stressed eels lowered against E. tarda but not against Vibrio anguillarum.

From these results, the increased susceptibility to the pathogens is interpreted as due to lowered phagocytosis.

致死濃度以下の銅液(100,250μg-Cu/l)に浸潰したニホンウナギ血漿コルチコステロイド量は, 12時間銅処理魚において最高値を示した。血中の白血球数(リンパ球, 顆粒球)は24時間銅処理魚において最も減少した。白血球の Edwardsiella tarda に対する食作用を in vitro で調べたところ, 24時間処理魚の白血球の食菌率は対照区のそれの半分程度に低下していた。以上の結果から, 先に報告した銅処理によるウナギの E. tarda などに対する感受性の増大は, ストレスの3次反応であり, 主として白血球の食菌作用の低下に起因するものと考えられた。

Zoology [ 480 ]

jpn

日本魚病学会

Copyright (c) 1985 The Japanese Society of Fish Pathology

[ISSN] 0388-788X

[ISSN] 1881-7335

[NCID] AN00063165