School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794-5000, USA.
J Invertebr Pathol. 2011 Feb;106(2):322-32. doi: 10.1016/j.jip.2010.11.004. Epub 2010 Nov 27.
Quahog Parasite Unknown (QPX) is a protistan parasite affecting hard clams Mercenaria mercenaria along the Northeastern coast of the United States. The geographic distribution and occurrence of disease epizootics suggests a primary role of temperature in disease development. This study was designed to investigate the effect of temperature on constitutive and QPX-induced defense factors in M. mercenaria. Control and QPX-challenged (both experimentally and naturally) clams were maintained at 13, 21 and 27°C for 4 months. Control and experimentally-infected clams originated from a southern broodstock (Florida, no prior reports of disease outbreak) while naturally-infected clams originated from a northern broodstock (Massachusetts, enzootic area). Standard and QPX-specific cellular and humoral defense parameters were assessed after 2 and 4 months. Measured parameters included total and differential hemocyte counts, reactive oxygen species production, phagocytic activity of hemocytes, lysozyme concentration in plasma, anti-QPX activity in plasma and resistance of hemocytes to cytotoxic QPX extracellular products. Results demonstrated a strong influence of temperature on constitutive clam defense factors with significant modulation of cellular and humoral parameters of control clams maintained at 13°C compared to 21 and 27°C. Similarly, clam response to QPX challenge was also affected by temperature. Challenged clams exhibited no difference from controls at 27°C whereas different responses were observed at 21°C and 13°C compared to controls. Despite differences in infection mode (experimentally or naturally infected) and clam origin (northern and southern broodstocks), similarities were observed at 13°C and 21°C between QPX infected clams from Florida and Massachusetts. Clam response to temperature and to QPX exhibited interesting relationship with QPX disease development highlighting major influence of temperature on disease development.
美国东北沿海的硬壳蛤 Mercenaria mercenaria 感染了一种原生动物寄生虫 Quahog Parasite Unknown（QPX）。疾病爆发的地理分布和发生表明温度在疾病发展中起着主要作用。本研究旨在调查温度对 M. mercenaria 固有和 QPX 诱导防御因子的影响。对照和 QPX 挑战（实验和自然）的蛤蜊在 13、21 和 27°C 下维持 4 个月。对照和实验感染的蛤蜊来自南方亲贝（佛罗里达州，没有疾病爆发的先前报告），而自然感染的蛤蜊来自北方亲贝（马萨诸塞州，地方性区域）。在 2 和 4 个月后评估了标准和 QPX 特异性细胞和体液防御参数。测量的参数包括总血细胞计数和差异、活性氧物质的产生、血细胞的吞噬活性、血浆中的溶菌酶浓度、血浆中的抗-QPX 活性以及血细胞对细胞毒性 QPX 细胞外产物的抵抗力。结果表明，温度对固有蛤蜊防御因子有强烈影响，与 21 和 27°C 相比，在 13°C 下维持的对照蛤蜊的细胞和体液参数有显著调节。同样，蛤蜊对 QPX 挑战的反应也受到温度的影响。在 27°C 下，受挑战的蛤蜊与对照无差异，而与对照相比，在 21°C 和 13°C 下观察到不同的反应。尽管感染模式（实验或自然感染）和蛤蜊来源（北方和南方亲贝）不同，但在 13°C 和 21°C 下，来自佛罗里达州和马萨诸塞州的 QPX 感染蛤蜊之间观察到相似之处。蛤蜊对温度和 QPX 的反应与 QPX 疾病发展之间存在有趣的关系，突出了温度对疾病发展的主要影响。
