Biochemical and histologic changes in red abalone (Haliotis rufescens)subjected to different combinations of temperature, food availability,and infection with the agent of withering syndrome

摘要

We conducted a long-term study to identify pathophysiologic changes that occur during progression of withering syndrome (WS) and to contrast these with changes due to starvation in uninfected animals. Following antibiotic treatment to assure all animals were free of the bacterial agent of WS (WS-RLP), farmed red abalone were subjected to eight separate treatment combinations of exposure to WS-RLP (exposed or unexposed), temperature (ambient or 19 degree C), and food availability (fed or starved). The digestive gland (DG) retained up to 186 ppm oxytetracycline at day 105 post-treatment. Though 0.1% of abalone sampled from exposed/ambient groups became infected over 497 days, 56% of abalone sampled from exposed/19 degree C groups became infected. Metaplastic DG changes occurred only in infected abalone. Metaplastic DG did not exhibit proliferation or apoptosis differing from normal DG. Abalone in the exposed/fed/19 degree C treatment had significantly more DG changes and infection intensities than those in the exposed/starved/19 degree C group (P < 0.05). Foot glycogen decrease preceded shrinkage, foot degeneration, and decrease in condition index. Progression of WS shared many features with starvation although changes in DG architecture appear pathognomic for this disease. Supported by California Sea Grant College Program award R/A 117 and the Marine Region, California Department of Fish and Game.