Asakawa Manabu, Beppu Rieko, Ito Katsutoshi, Tsubota Makiko, Takayama Haruyoshi, Miyazawa Keisuke
Department of Bioresource Science and Technology, Graduate School of Biosphere Science, Hiroshima University, 1-4-4, Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8528, Japan.
Shokuhin Eiseigaku Zasshi. 2006 Feb;47(1):28-32. doi: 10.3358/shokueishi.47.28.
As a part of our studies on the mechanism of uptake of paralytic shellfish poison (PSP) and the kinetics of its accumulation in bivalves, oysters Crassostrea gigas were experimentally contaminated with PSP by being fed with the toxic dinoflagellate Alexandrium tamarense for 2, 4, 6, 8 and 10 days. Temporal variations in the PSP contents and their profiles in oysters during the feeding experiment were monitored by high-performance liquid chromatography (HPLC) and the toxin profile of the oysters was compared with that of A. tamarense. Toxins excreted from the infested oysters into the seawater for 2 and 10 days were recovered and analyzed by HPLC. PSP toxicity rapidly appeared in the tissues of oysters and their toxicity levels reached 0.6 (0.3), 2.2 (1.1), 1.0 (0.5), 3.4 (1.6) and 1.1 (0.5) MU/g (nmol/g) shucked meat at 2, 4, 6, 8 and 10 days, respectively. The accumulation rates of toxin, calculated from the total amount (nmol) of toxins expressed by the total cell number fed during the exposure period and the toxicity of the oysters, were 14.1, 18.7, 5.1, 14.9 and 3.2% for 2, 4, 6, 8 and 10 days. During feeding experiments, the toxin profile of oysters changed substantially, showing marked differences from the proportions found in the toxigenic dinoflagellate used as food. The toxin components in this strain existed almost exclusively as beta-epimers, which accounted for 66.3 mol% of the total. This contrasts with the case of the oysters, where the beta-epimers represented 24.8, 29.8, 25.1, 27.3 and 25.2 mol% of the total at 2, 4, 6, 8 and 10 days, respectively. The amount of gonyautoxin-1 (GTX1) accumulated in oysters increased linearly and slowly for 8 days and the maximum content of GTX1 reached 51.3 mol%. The composition of GTX group compounds recovered from the seawater in which the oysters had been reared was a little different from that within the oyster tissues.
作为我们对麻痹性贝类毒素（PSP）摄取机制及其在双壳贝类中积累动力学研究的一部分，通过用有毒的甲藻塔玛亚历山大藻（Alexandrium tamarense）喂养2、4、6、8和10天，对太平洋牡蛎（Crassostrea gigas）进行了PSP实验性污染。在喂养实验期间，通过高效液相色谱法（HPLC）监测牡蛎中PSP含量的时间变化及其分布，并将牡蛎的毒素分布与塔玛亚历山大藻的毒素分布进行比较。收集受感染牡蛎在2天和10天内排泄到海水中的毒素，并用HPLC进行分析。PSP毒性在牡蛎组织中迅速出现，其毒性水平在2、4、6、8和10天时分别达到0.6（0.3）、2.2（1.1）、1.0（0.5）、3.4（1.6）和1.1（0.5）MU/g（nmol/g）去壳肉。根据暴露期间投喂的总细胞数所表达的毒素总量（nmol）和牡蛎的毒性计算出的毒素积累率，在2、4、6、8和10天时分别为14.1%、18.7%、5.1%、14.9%和3.2%。在喂养实验期间，牡蛎的毒素分布发生了显著变化，与用作食物的产毒甲藻中发现的比例有明显差异。该菌株中的毒素成分几乎完全以β-差向异构体形式存在，占总量的66.3摩尔%。这与牡蛎的情况形成对比，在2、4、6、8和10天时，β-差向异构体分别占总量的24.8%、29.8%、25.1%、27.3%和25.2%。牡蛎中积累的膝沟藻毒素-1（GTX1）的量在8天内呈线性缓慢增加，GTX1的最大含量达到51.3摩尔%。从养殖牡蛎的海水中回收的GTX类化合物的组成与牡蛎组织内的组成略有不同。
