Asakawa Manabu, Takayama Haruyoshi, Beppu Rieko, 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. 2005 Dec;46(6):246-50. doi: 10.3358/shokueishi.46.246.
To assess levels of shellfish intoxication by the paralytic shellfish poison (PSP)-producing dinoflagellate Alexandrium tamarense, potential health risks to human shellfish consumers and the possible need for regulatory intervention, yearly variations of maximum cell density of this species were examined from 1993 to 2004 in Kure Bay and Kaita Bay, which are located within Hiroshima Bay, Hiroshima Prefecture, Japan. The seawater temperature was determined concomitantly. In Kure Bay, maximum concentrations of 1,400 and 1,300 cells/mL at 0 and 5 m depths were observed on 21 and 24 April 1997. In Kaita Bay, remarkably high concentrations above 1,000 cells/mL of A. tamarense were observed in two out of three years investigated. These facts suggest that the environment in both bays is favorable for the propagation of A. tamarense. The temperature range at which the natural population of A. tamarense blooms was generally from 12 to 16 degrees C. Four strains (ATKR-94, -95, -97 and -01) from Kure Bay and one strain (ATKT-97) from Kaita Bay were established. The strain ATKR-94, cultured in modified SW-2 medium at 15 degrees C for 15 days, showed a specific toxicity of 33.8 x 10(-6) MU/cell. The toxins in all five strains exist almost exclusively as beta-epimers (C2 (PX2 or GTX8), GTX3, dcGTX3 and GTX4), which accounted for 54.9 to 73.0 mol% of the total. The corresponding a-epimers (C1 (PX1 or epi-GTX8), GTX2, dcGTX2 and GTX1) accounted for 6.0 to 28.9 mol%. The toxin profiles of ATKR-97 and ATKT-97 were characterized by unusually high proportions of low-potency sulfocarbamoyl toxin, which comprised 62.4 and 68.2 mol%, respectively, of total toxins. In the toxic bivalves, the low-toxicity sulfocarbamoyl components, major components of A. tamarense, were present in amounts of only a few percent, suggesting that in vivo conversion of PSP occurs after ingestion. A comparison of the toxin profiles of the causative dinoflagellate and contaminated bivalves showed that PSP components exist in the bivalves in the form of alpha-epimers, presumably owing to accumulation or storage of the toxins.
为评估由产麻痹性贝类毒素（PSP）的甲藻塔玛亚历山大藻引起的贝类中毒水平、食用贝类的人类所面临的潜在健康风险以及监管干预的必要性，1993年至2004年期间，对位于日本广岛县广岛湾内的吴湾和海田湾中该物种的最大细胞密度年变化进行了研究。同时测定了海水温度。在吴湾，1997年4月21日和24日在0米和5米深度分别观测到最大浓度为1400和1300个细胞/毫升。在海田湾，在调查的三年中有两年观测到塔玛亚历山大藻浓度显著高于1000个细胞/毫升。这些事实表明，两个海湾的环境都有利于塔玛亚历山大藻的繁殖。塔玛亚历山大藻自然种群大量繁殖的温度范围一般为12至16摄氏度。建立了来自吴湾的4个菌株（ATKR - 94、- 95、- 97和- 01）和来自海田湾的1个菌株（ATKT - 97）。菌株ATKR - 94在改良的SW - 2培养基中于15摄氏度培养15天，显示出比毒性为33.8×10⁻⁶MU/细胞。所有5个菌株中的毒素几乎全部以β-表异构体（C2（PX2或GTX8）、GTX3、dcGTX3和GTX4）形式存在，占总量的54.9%至73.0摩尔%。相应的α-表异构体（C1（PX1或表-GTX8）、GTX2、dcGTX2和GTX1）占6.0%至28.9摩尔%。ATKR - 97和ATKT - 97的毒素谱特征是低效磺基甲酰基毒素比例异常高，分别占总毒素的62.4%和68.2%。在有毒双壳贝类中，作为塔玛亚历山大藻主要成分的低毒性磺基甲酰基成分仅占百分之几，这表明PSP在摄入后发生了体内转化。对致病甲藻和受污染双壳贝类毒素谱的比较表明，PSP成分在双壳贝类中以α-表异构体形式存在，推测是由于毒素的积累或储存。
