| 杨越聪,郑关超,赵辉辉,张海涛,谭志军,吴海燕.厚壳贻贝中麻痹性贝毒的蓄积及其对滤食率的影响.渔业科学进展,2024,45(5):224-233 |
| 厚壳贻贝中麻痹性贝毒的蓄积及其对滤食率的影响 |
| Accumulation of paralytic shellfish toxins in Mytilus unguiculatus and its effect on filtration rate |
| 投稿时间：2023-07-11 修订日期：2023-09-18 |
| DOI： |
| 中文关键词: 厚壳贻贝 麻痹性贝毒 生物转化 滤食率 |
| 英文关键词: Mytilus unguiculatus Paralytic shellfish toxins Biotransformation Filtration rate |
| 基金项目:国家自然科学基金(32072329)和现代农业产业技术体系专项资金(CARS-49)共同资助 |
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| 中文摘要: |
| 厚壳贻贝(Mytilus unguiculatus)是中国地理标志产品，具有重要的经济价值和产业地位。随着我国近海有害赤潮灾害的频发，厚壳贻贝中贝类毒素残留风险亟需关注。本研究通过室内暴露方式，评估了不同密度链状亚历山大藻(Alexandrium catenella)对厚壳贻贝滤食率的影响及其对麻痹性贝毒(paralytic shellfish toxins，PSTs)的蓄积代谢规律。结果表明，厚壳贻贝滤食率与产毒藻暴露密度、PSTs含量呈显著负相关(P<0.05)，最低降至初始值的30.0%左右。厚壳贻贝对PSTs整体蓄积能力较弱，高密度组肝胰腺与软组织的日平均蓄积速率分别为981.6 μg STXeq/kg/d和106.5 μg STXeq/kg/d。链状亚历山大藻与厚壳贻贝中N-磺酰氨甲酰基类毒素-2 (N-sulfocarbamoylgonyautoxin toxins-2, C1)、N-磺酰氨甲酰基类毒素-3(C2)与膝沟藻毒素5 (Gonyautoxin-5, GTX5) 3种组分的初始含量最高，贻贝摄食产毒藻后肝胰腺中C2占比显著降低(P<0.05)，由74.1% (藻细胞)分别降低至22.6% (高密度组)与17.1%(低密度组)；C1占比则由10.6% (藻细胞)上升至54.1% (高密度组)和54.0% (低密度组)。厚壳贻贝的代谢速率最高可达到1 860.3 μg STXeq/kg/d，显著高于其他双壳贝类。本研究表明，厚壳贻贝滤食率随PSTs产毒藻暴露时间呈下降趋势，且厚壳贻贝对PSTs的快速代谢与低转化、低残留等特点也表明其食用风险低于其他贻贝。本研究为评估厚壳贻贝中PSTs风险形成机理并为科学构建防控技术提供了研究基础。 |
| 英文摘要: |
| Paralytic shellfish toxins (PSTs) are a class of neurotoxic marine biotoxins that are widely distributed and cause more than 2,000 poisoning events worldwide each year, with mortality rates of up to 15%. PSTs can accumulate through the food chain and are mainly distributed in marine organisms such as bivalve mollusks. Several countries and regions, including the European Union, China, and the United States, have established strict regulatory limits (400 MU/100 g or 800 μg STXeq/kg) for PSTs and implemented monitoring programs. As reported previously, factors such as filtration rate, selective feeding, and the efficiency of the organism in absorbing toxin-producing algae can significantly affect the accumulation of PSTs in bivalve mollusks. Mytilus unguiculatus is one of three major commercial mussel species in China, with important economic value and social impact. Due to its high nutritional value, it is extensively cultured as an important shellfish species in the Zhoushan archipelago of Zhejiang Province in China. Alexandrium spp. are the main toxin-producing algae in the area. PSTs have been detected in mussels between May and July after harmful algal blooms. Research into the elimination characteristics of PSTs accumulation in M. unguiculatus is urgently needed to establish a monitoring and control program.
In this study, 760 mussels were randomly selected and fed A. catenella at different cell densities, with a high-density group (7.00105 cells/d), a low-density group (2.80105 cells/d), and a control group. The experimental period lasted for 30 d, during which the accumulation period approximately represented days 1–7 and the elimination period days 8–30 d. A total of 14 sampling points were set up on days 0.5, 1, 2, 4, 6, and 7 of the accumulation period and days 1, 3, 5, 7, 11, 15, 19, and 23 of the elimination period. Six mussels were randomly collected at each sampling point and dissected into soft tissues, hepatopancreas, and edible tissues. Liquid chromatography-tandem mass spectrometry was used to determine the content of PSTs. During the accumulation period, 5 mL culturing seawater was collected during or 1 h after feeding, and Ruge's solution was added. The filtration rate of the mussels was determined by counting the quantity of A. catenella cells in the water. The results showed that the toxins in M. unguiculatus were not equally distributed. The highest PST content in hepatopancreas tissues was 7,458.2 μg STXeq/kg (high-density group) and 2,555.9 μg STXeq/kg (low-density group). The highest PST content in edible tissues was 108.6 μg STXeq/kg (high-density group). The hepatopancreas was identified as a target organ for toxin accumulation. From day 3 to day 7, the filtration rate of mussels decreased, eventually reaching 30% of its initial value. The filtration rate of M. unguiculatus in the high-density group was not significantly different from that of the low-density group during days 1–5 and was significantly lower during days 5–7. During the elimination phase, the PST elimination rate in mussels was 18.4% (hepatopancreas), 18.1% (soft tissues), and 13.1% (edible tissues). At day 30, the residual content of PSTs in the hepatopancreas of mussels was approximately 1 400 μg STXeq/kg in the high-density group and 600.0 μg STXeq/kg in the low-density group. Changes in the proportion of each PST component were transferred from A. catenella to M. unguiculatus. The proportion of C2 was significantly reduced from 74.1% (A. catenella) to 22.6% (high-density group) and 17.1% (low-density group) (P<0.05); the percentage of C1 increased from 10.6% (A. catenella) to 54.1% (high-density group) and 54.0% (low-density group) (P<0.05). No significant difference was observed in the percentage of GTX5 between A. catenella and mussels in the different density groups (P>0.05). No significant conversion was observed between the PST components in the hepatopancreas of mussels throughout the experiment.
Our data indicate that the daily accumulation rate of PSTs in M. unguiculatus was lower than that in other mussels. Moreover, the toxin elimination rate was higher than that of other mussels. A negative correlation was observed between the filtration rate of M. unguiculatus and the PST content of each tissue type. These results show that M. unguiculatus is more sensitive to PSTs than other mussels. During the stage of PST transfer from A. catenella to M. unguiculatus, a high proportion of C2 toxin was converted to C1 toxin. After accumulating in the hepatopancreas, the PST profile exhibited relatively stable performance. In summary, we conclude that, due to higher susceptibility to toxins and lower conversion rates, a lower risk is associated with the consumption of M. unguiculatus than with that of other mussels. Our findings will contribute to improving our understanding of the mechanisms underlying the PST accumulation risk in M. unguiculatus and provide valuable scientific insights for developing prevention and risk management strategies concerning PSTs. |
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