Genthner F J, Volety A K, Oliver L M, Fisher W S
U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory and Gulf Ecology Division, Gulf Breeze, Florida 32561, USA.
Appl Environ Microbiol. 1999 Jul;65(7):3015-20. doi: 10.1128/AEM.65.7.3015-3020.1999.
A tetrazolium dye reduction assay was used to study factors governing the killing of bacteria by oyster hemocytes. In vitro tests were performed on bacterial strains by using hemocytes from oysters collected from the same location in winter and summer. Vibrio parahaemolyticus strains, altered in motility or colonial morphology (opaque and translucent), and Listeria monocytogenes mutants lacking catalase, superoxide dismutase, hemolysin, and phospholipase activities were examined in winter and summer. Vibrio vulnificus strains, opaque and translucent (with and without capsules), were examined only in summer. Among V. parahaemolyticus and L. monocytogenes, significantly (P < 0.05) higher levels of killing by hemocytes were observed in summer than in winter. L. monocytogenes was more resistant than V. parahaemolyticus or V. vulnificus to the bactericidal activity of hemocytes. In winter, both translucent strains of V. parahaemolyticus showed significantly (P < 0.05) higher susceptibility to killing by hemocytes than did the wild-type opaque strain. In summer, only one of the V. parahaemolyticus translucent strains showed significantly (P < 0.05) higher susceptibility to killing by hemocytes than did the wild-type opaque strain. No significant differences (P > 0.05) in killing by hemocytes were observed between opaque (encapsulated) and translucent (nonencapsulated) pairs of V. vulnificus. Activities of 19 hydrolytic enzymes were measured in oyster hemolymph collected in winter and summer. Only one enzyme, esterase (C4), showed a seasonal difference in activity (higher in winter than in summer). These results suggest that differences existed between bacterial genera in their ability to evade killing by oyster hemocytes, that a trait(s) associated with the opaque phenotype may have enabled V. parahaemolyticus to evade killing by the oyster's cellular defense, and that bactericidal activity of hemocytes was greater in summer than in winter.
采用四氮唑染料还原试验研究了影响牡蛎血细胞杀灭细菌的因素。利用冬季和夏季从同一地点采集的牡蛎血细胞，对细菌菌株进行了体外试验。对冬季和夏季的副溶血性弧菌菌株（其运动性或菌落形态发生改变，包括不透明和半透明型）以及缺乏过氧化氢酶、超氧化物歧化酶、溶血素和磷脂酶活性的单核细胞增生李斯特菌突变体进行了检测。创伤弧菌菌株（不透明和半透明型，有或无荚膜）仅在夏季进行了检测。在副溶血性弧菌和单核细胞增生李斯特菌中，夏季血细胞的杀菌水平显著（P < 0.05）高于冬季。单核细胞增生李斯特菌比副溶血性弧菌或创伤弧菌对血细胞的杀菌活性更具抗性。在冬季，副溶血性弧菌的两种半透明菌株对血细胞杀灭的敏感性显著（P < 0.05）高于野生型不透明菌株。在夏季，副溶血性弧菌的半透明菌株中只有一种对血细胞杀灭的敏感性显著（P < 0.05）高于野生型不透明菌株。在创伤弧菌的不透明（有荚膜）和半透明（无荚膜）菌株对之间，未观察到血细胞杀灭作用的显著差异（P > 0.05）。测定了冬季和夏季采集的牡蛎血淋巴中19种水解酶的活性。只有一种酶，即酯酶（C4），其活性存在季节性差异（冬季高于夏季）。这些结果表明，不同细菌属逃避牡蛎血细胞杀灭的能力存在差异，与不透明表型相关的一个或多个特征可能使副溶血性弧菌能够逃避牡蛎细胞防御的杀灭作用，并且血细胞的杀菌活性夏季高于冬季。
