Improved Isolation Procedures for Okadaic Acid Group Toxins from Shellfish (Mytilus edulis) and Microalgae (Prorocentrum lima)

Okadaic acid (OA) group toxins may accumulate in shellfish and can result in diarrhetic shellfish poisoning when consumed by humans, and are therefore regulated. Purified toxins are required for the production of certified reference materials used to accurately quantitate toxin levels in shellfish and water samples, and for other research purposes. An improved procedure was developed for the isolation of dinophysistoxin 2 (DTX2) from shellfish (M. edulis), reducing the number of purification steps from eight to five, thereby increasing recoveries to ~68%, compared to ~40% in a previously reported method, and a purity of >95%. Cell densities and toxin production were monitored in cultures of Prorocentrum lima, that produced OA, DTX1, and their esters, over ~1.5 years with maximum cell densities of ~70,000 cells mL⁻¹ observed. Toxin accumulation progressively increased over the study period, to ~0.7 and 2.1 mg L⁻¹ of OA and DTX1 (including their esters), respectively, providing information on appropriate harvesting times. A procedure for the purification of OA and DTX1 from the harvested biomass was developed employing four purification steps, with recoveries of ~76% and purities of >95% being achieved. Purities were confirmed by LC-HRMS, LC-UV, and NMR spectroscopy. Additional stability observations led to a better understanding of the chemistry of these toxins.     

东海原甲藻对褶皱臂尾轮虫实验种群动态的影响

采用生命表方法研究了不同密度东海原甲藻(Prorocentrum donghaiense)对褶皱臂尾轮虫(Brachionus plicatilis)生命周期中各发育阶段历时以及种群增长参数的影响。结果表明：东海原甲藻对褶皱臂尾轮虫的生长发育具有明显的影响,使轮虫的胚胎发育和繁殖前期延长,繁殖期、繁殖后期和平均寿命缩短,产卵量和繁殖率降低。随藻密度的增加,胚胎发育和繁殖前期分别从(18.33±7.26)h和(58.26±3.52)h增加到(24.29±4.86)h和(91.74±15.46)h,而繁殖后期则从(48.86±14.73)h缩短至(22.60±4.80)h。轮虫的净生殖率和内禀增长率均低于对照(P<0.05或P<0.01),反映了赤潮微藻对轮虫种群增长的影响。不同藻密度下轮虫能够维持一定的种群增长。赤潮藻和浮游动物关系的进一步研究对于我们了解其对海洋生态系统的影响和作用机制具有重要意义.