Zebrafish (Brachydanio rerio) were exposed to PCBs (50 μg/L) for 4 weeks. The gill and the liver morphology were examined by transmission eletron microslogy. Results indicated that the membrane and partial cytoplasm of the epithelium cell in secondary lamella collapsed with lots of mucous and cell debris lying around. Hepatic cells which exposed to PCBs for 4 weeks showed the deforming nuclear deviated from cell centre, mitochondrim collapsed and rough-surfaced endoplasmic reticulum fractured. Furthermore, there were lots of lipofuscin granule and lipid droplet in the cytoplasm of the damaged cells.
Three bacteria strains were isolated from the skin tissue of Rana grylio with "necrotic skin disease".After artificial infection by the bacteria strain skin 1-3 was determined to be the pathogen of the "necrotic skin disease".It was identified to be Acinetobacter lwoffii by VITEK-AMS-60 automatic identification system.The bacteria were rod shaped with a size of (0 75～0 93 ) μm×(1 5～2) μm, Gram-negative, and non-mobile. It was sensitive to 17 species of drugs and resistant to 5 drugs.
