福氏拟菱形藻(Pseudo-nitzschia fukuyoi)——中国产毒拟菱形藻的新记录

摘要

为了提高对我国海域拟菱形藻属(Pseudo-nitzschia)物种多样性的认识,并明确其是否能够产生多莫酸(domoic acid,DA).本文从中国沿海分离和建立了拟菱形藻的单克隆培养株系,结合光学显微镜下的群体特征、透射电镜下的超微形态学特征、基于核糖体转录间隔区(internal transcribed spacer,ITS)的分子系统学数据,以及基于ITS2转录RNA的二级结构分析,鉴定到我国拟菱形藻属的1个新记录种:福氏拟菱形藻(P.fukuyoi Lim,Teng,Leaw&Lim).本文对其形态学特征进行描述,与相似物种进行了对比分析;对其ITS2-RNA序列进行了分析;利用高效液相色谱-串联质谱联用法(liquid chromatography tandem mass spectrometry,LC-MS/MS)对培养藻株的产毒特征进行了分析,多个株系中均检测到DA,单细胞产毒水平为0.02-0.23pg,这是我国报道的第二种产毒拟菱形藻.利用卤虫(Artemia salina)和褶皱臂尾轮虫(Brachionus plicatilis)对福氏拟菱形藻的产毒水平进行了诱导,发现浮游动物能够提高福氏拟菱形藻的DA含量,增强幅度在4.7-28.5倍之间.本文提高了对我国拟菱形藻属物种多样性的认识,明确了福氏拟菱形藻的产毒特征和水平,为后续深入研究提供了基础数据.%To clarify the species diversity of the genus Pseudo-nitzschia in China and declare their domoic acid (DA) production,a set of monoclonal strains were isolated and established from Chinese coastal waters in this study.Based on the morphology under light microscope (LM) and transmission electron microscopy (TEM),and molecular analysis inferred from internal transcribed spacer (ITS) region of ribosomal rRNA encoding gene,and comparison of ITS2-RNA secondary structure,a new record Pseudo-nitzschia species for China was identified:P.fukuyoi Lim,Teng,Leaw & Lim.Its morphological features was described in detail and compared with similar species,and the unique molecular feature for the secondary structure of ITS2-RNA was analyzed.Using liquid chromatography tandem mass spectrometry (LC-MS/MS) injection,DA could be detected from all five established P.fukuyoi strains,with concentrations around 0.02-0.23 pg cell-1.In addition,Artemia salina and Brachionus plicatilis were used to mix-culture with P.fukuyoi strains,to evaluate the impact on the ability of DA-production.The result show that the existence of zooplankton could increase DA-production level of P.fukuyoi for 4.7-28.5 times.The discovery enriches the diversity of the genus Pseudo-nitzschia in China,and report a new toxic Pseudo-nitzschia species,P.fukuyoi,which can provide basic data for further studies.