两种贻贝对麻痹性贝类毒素蓄积代谢及生理应激的比较研究

COMPARISON IN ACCUMULATION,METABOLISM AND PHYSIOLOGICAL STRESS OF PARALYTIC SHELLFISH TOXINS IN TWO SPECIES OF MUSSELS

贻贝是我国沿海常见的经济贝类,作为监测海洋污染情况的前哨物种对多种贝类毒素均具有较强的蓄积能力,但不同贻贝蓄积能力的种间差异尚不清晰。基于贝类软组织质量比原则,将紫贻贝与厚壳贻贝分别暴露于链状亚历山大藻,研究两种贻贝对麻痹性贝类毒素(paralytic shellfish toxins,PSTs)的蓄积代谢与生理应激差异。结果表明,紫贻贝和厚壳贻贝中PSTs最高蓄积量分别为889.1和358.6μg STXeq/kg,前者超出后者的2倍。代谢3天后,厚壳贻贝PSTs的清除率为88.8%,而紫贻贝仅为42.5%。皮尔逊相关性分析表明,两种贻贝各组织单日PSTs蓄积量与其产毒藻吸收率呈显著正相关(P<0.05),而与清滤率无显著相关性(P>0.05)。在生理应激方面,紫贻贝对产毒藻的清滤率与吸收率为厚壳贻贝的两倍。此外,紫贻贝肝胰腺组织的氧化应激与组织损伤更严重,导致其肝胰腺中PSTs向其他组织转移量与清除率均显著低于厚壳贻贝(P<0.05)。综上所述,产毒藻暴露下厚壳贻贝通过改变摄食行为降低PSTs的蓄积量,导致厚壳贻贝中PSTs的安全风险明显低于紫贻贝,研究结果为探究不同双壳贝类对PSTs的蓄积差异机理提供了思路。

Mussels exhibit a robust capacity for environmental adaptation and are often utilized as indicators to environmental pollution.It is known that mussels accumulate toxins during harmful algal blooms at a significantly higher rate than other bivalve mollusks do.Two mussel species,M.unguiculatus and M.galloprovincialis,were chosen for our exposure experiments in this regard.Mussels were fed with toxin-producing algae(Alexandrium catenella)based on their soft tissue weight ratio.After 7 days of accumulation,M.galloprovincialis showed the highest content of PSTs at 889.1μg STXeq/kg,surpassing the limit of 800μg STXeq/kg.In contrast,the PSTs content in M.unguiculatus was relatively lower at 358.6μg STXeq/kg.The rate of PSTs elimination in M.galloprovincialis(88.8%)was significantly higher than that in M.unguiculatus(42.5%).The rates of daily PSTs accumulation in M.galloprovincialis and M.unguiculatus exhibited a significant positive correlation with the absorption efficiency(P<0.05),whereas no significant correlation with the clearance rate(P>0.05)was observed.The clearance rate and absorption efficiency of M.galloprovincialis to toxin-producing algae were twice as high as those of M.unguiculatus.Additionally,the hepatopancreas of M.galloprovincialis exhibited more severe oxidative stress and pathological damage,resulting in reduced tissue transfer of PSTs and a lower elimination rate compared to M.unguiculatus.The proportion of PSTs in the edible tissue of M.galloprovincialis was found higher than those in M.unguiculatus.M.unguiculatus could reduce toxin accumulation through decreased feeding behavior,whereas M.galloprovincialis showed a notable oxidative stress response in the presence of high PSTs contents.Therefore,distinctions in physiological stress ultimately resulted in the variations in the accumulation of PSTs between the two mussel species。