INRH (Moroccan Institute of Fisheries Research), Marine Environment Monitoring Laboratory, Tangier, Morocco; Equipe de Biotechnologie Végétale, Faculty of Sciences, Abdelmalek Essaadi University, Tetouan, Morocco; Univ Montpellier, IRD, CNRS, IFREMER, MARBEC laboratory, Place Eugène Bataillon, 34095 Montpellier, France.
INRH (Moroccan Institute of Fisheries Research), Marine Environment Monitoring Laboratory, Tangier, Morocco.
Sci Total Environ. 2024 Oct 1;945:174094. doi: 10.1016/j.scitotenv.2024.174094. Epub 2024 Jun 19.
The dinoflagellate Gymnodinium catenatum is considered the primary cause of recurrent paralytic shellfish toxins (PSTs) in shellfish on the Moroccan Mediterranean coasts. The impacts of key environmental factors on the growth, cell yield, cell size and PST content of G. catenatum were determined. Results indicated that increasing salinity from 32 to 39 and nitrate concentrations from 441 μM to 1764 μM did not significantly (ANOVA, P-value >0.63) modify the growth rate of the studied species. Gymnodinium catenatum exhibited the highest growth rate at 24 °C. Cells arrested their division at 15 °C and at ammonium concentration above 441 μM, suggesting that this nitrogen form is toxic for G. catenatum. Furthermore, G. catenatum was unable to assimilate urea as a nitrogen source. In G. catenatum cells, eight analogues of saxitoxin were detected, belonging to the N-sulfocarbamoyl (C1-4, B1 and B2) and decarbamoyl (dc-GTX2/3) toxins. C-toxins contributed 92 % to 98 % of the molar composition of the PSTs. During the exponential growth, C2 tended to dominate, while C3 prevailed during the stationary phase. Toxin content per cell (ranging from 5.5 pg STXeq.cell to 22.4 pg STXeq.cell) increased during the stationary growth phase. Cell toxin content increased with the concentrations of nitrate, ranging from 12.1 pg STXeq.cell at 441 μM to 22.4 pg STXeq.cell at 1764 μM during the stationary growth phase. The toxin content of G. catenatum showed the highest values measured at the highest tested temperatures, especially during the stationary phase, where toxicity reached 17.8 pg STXeq.cell and 16.4 pg STXeq.cell at 24 °C and 29 °C, respectively. The results can help understand the fluctuations in the growth and PST content of G. catenatum in its habitat in response to changing environmental variables in the Mediterranean Sea when exposed to increases in warming pressure and eutrophication.
短沟藻被认为是导致摩洛哥地中海沿岸贝类中反复出现麻痹性贝类毒素（PSTs）的主要原因。本研究确定了关键环境因素对短沟藻生长、细胞产率、细胞大小和 PST 含量的影响。结果表明，盐度从 32 增加到 39 和硝酸盐浓度从 441 μM 增加到 1764 μM 并没有显著改变（ANOVA，P 值>0.63）研究物种的生长速度。短沟藻在 24°C 时表现出最高的生长速度。细胞在 15°C 和铵浓度高于 441 μM 时停止分裂，表明这种氮形式对短沟藻有毒。此外，短沟藻无法将尿素作为氮源同化。在短沟藻细胞中，检测到 8 种石房蛤毒素类似物，属于 N-磺甲酰基（C1-4、B1 和 B2）和脱磺酰基（dc-GTX2/3）毒素。C 毒素占 PSTs 摩尔组成的 92%至 98%。在指数生长期，C2 倾向于占主导地位，而 C3 在静止期占主导地位。每个细胞的毒素含量（范围为 5.5 pg STXeq.cell 至 22.4 pg STXeq.cell）在静止生长阶段增加。细胞毒素含量随着硝酸盐浓度的增加而增加，从 441 μM 时的 12.1 pg STXeq.cell 增加到静止生长阶段的 1764 μM 时的 22.4 pg STXeq.cell。在最高测试温度下，短沟藻的毒素含量最高，尤其是在静止期，在 24°C 和 29°C 时分别达到 17.8 pg STXeq.cell 和 16.4 pg STXeq.cell 的毒性。这些结果可以帮助了解在变暖压力和富营养化增加的情况下，短沟藻在其栖息地中的生长和 PST 含量的波动情况，以响应地中海环境中变化的环境变量。
