육상 수조에서 사육 중인 숭어 (Mugil cephalus)의 Amyloodinium sp. 감염

Amyloodinium sp. Infestation in Mullet (Mugil cephalus) cultured in a pond on land

  • 발행 : 2006.04.01

초록

육상수조에 양식중인 폐사가 발생하는 숭어 (Mugil cephalus)를 조사한 결과 아가미와 지느러미에 Amyloodinium sp.의 감염이 확인되었다. 아가미의 무염색표본을 검경하면 충체는 불투명한 원형 또는 난원형으로 중심부에 밝게 보이는 핵을 가지고 있는데, Lugol 액 이나 Diff-Quick III액을 적하하여 충체는 각각 검은색과 청색으로 염색된다. 또 충체를 May-Grunwald Giemsa염색하면 세포질의 주변부는 과립성의 호산성이지만 가운데 부위는 과립성의 호염기성으로 염색되는데, 도은염색에서 세포질의 과립은 음성, 중심부의 과립은 양성이었으며, 도은 양성과립은 Lugol 액에 갈색으로 염색되었다. 분리한 충체를 여과멸균해수에 넣어 20℃에서 배양하였을 엷은 이중막인 시스트막이 형성되면서 2분열을 일으켜 최종적으로 시스트막이 파열되면서 수많은 dinospores가 방출되었다. 병리조직학적으로는 아가미 상피세포의 증생으로 인한 새변의 유착, 곤봉화 및 변형이 일어나 병어는 호흡곤란을 일으키는 것으로 판단되었다.

Amyloodinium sp. was found on the gills of mullet (Mugil cephalus) cultured on land. No external symptoms in the diseased fish were found except decoloration of the gills. In fresh preparations of the gills the parasites were opaque round or oval shape with a bright nucleus and 43.5 ㎛ (18.2~72.7, n=20) in size. In preparations added a drop of Lugol solution, they were black with the same shapes in fresh preparations and 43.5 ㎛ (n=20) in size. The parasites were stained black and blue in a droplet of Lugol solution and Diff-Quick III solution, respectively and their sizes were a little larger than in wet preparations. After stained with May-Grunwald Giemsa, the parasites appeared granular eosinophlic in the peripheral cytoplasm and granular strong basophilic in the center. In silver impregnated specimens the peripheral granules were negative and the central ones positive. The granules appeared brown in purplish cytoplasm after staining with Lugol solution. The parasites developed by binary division when they were cultivated in filtered seawater at 20℃. Histopathologically severe epithelial hyperplasia and fusion in the gill filaments resulted in clubbing, especially the proximal region of the filament. Epithelial hyperplasia was also found in the basal regions of the gill filaments and some epithelial cells were occasionally detached from the filaments. Some pear-shaped trophonts of the parasites with rhizoid attached on the gill filaments showing hyperplasia of the epithelial cells and mucous cells.

키워드

참고문헌

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