Third Institute of Oceanography, SOA, Xiamen 361005, China.
Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, D-27570 Bremerhaven, Germany.
Harmful Algae. 2017 Jun;66:65-78. doi: 10.1016/j.hal.2017.05.001. Epub 2017 May 24.
The marine planktonic dinophyceaen genus Azadinium is a primary source of azaspiracids, but due to their small size its diversity may be underestimated and information on its biogeography is still limited. A new Azadinium species, A. zhuanum was obtained from the East China Sea and Yellow Sea of China by incubating surface sediments. Five strains were established by isolating single germinated cells and their morphology was examined with light microscopy and scanning electron microscopy. Azadinium zhuanum was characterized by a plate pattern of Po, cp, X, 4', 2a, 6'', 6C, 5S, 6''', 2'''', by a distinct ventral pore at the junction of Po, the first and fourth apical plates, and a conspicuous antapical spine. Moreover, Azadinium poporum was obtained for the first time from the Mediterranean by incubating surface sediment collected from Diana Lagoon (Corsica) and a new strain of Azadinium dalianense was isolated from the French Atlantic. The morphology of both strains was examined. Small subunit ribosomal DNA (SSU rDNA), large subunit ribosomal DNA (LSU rDNA) and internal transcribed spacer (ITS) sequences were obtained from cultured strains. In addition, LSU sequences were obtained by single cell sequencing of two presumable A. poporum cells collected from the French Atlantic. Molecular phylogeny based on concatenated SSU, LSU and ITS sequences revealed that A. zhuanum was closest to A. polongum. French A. poporum from Corsica (Mediterranean) and from the Atlantic showed some genetic differences but were nested within one of the A. poporum ribotypes together with other European strains. Azadinium dalianense from France together with the type strain of the species from China comprised a well resolved clade now consisting of two ribotypes. Azaspiracid profiles were analyzed for the cultured Azadinium strains using LC-MS/MS and demonstrate that the Mediterranean A. poporum strain produced AZA-2 and AZA-2 phosphate with an amount of 0.44fgcell. Azadinium zhuanum and A. dalianense did not produce detectable AZA. Results of the present study support the view of a high diversity and wide distribution of species belonging to Azadinium. The first record of AZA-2 producing A. poporum from the Mediterranean suggests that this species may be responsible for azaspiracid contaminations in shellfish from the Mediterranean Sea.
浮游甲藻属的海洋浮游甲藻是azaspiracids 的主要来源，但由于其体型较小，其多样性可能被低估，其生物地理学信息仍然有限。通过培养表层沉积物，从中国的东海和黄海获得了一种新的 Azadinium 物种，A. zhuanum。通过分离单个发芽细胞建立了五个菌株，并通过光学显微镜和扫描电子显微镜检查了它们的形态。Azadinium zhuanum 的特征是 Po、cp、X、4'、2a、6''、6C、5S、6'''、2''''''，在 Po、第一和第四顶片的连接处有一个明显的腹孔，以及一个显眼的反顶刺。此外，通过从戴安娜泻湖（科西嘉岛）采集的表层沉积物培养，首次从地中海获得了 Azadinium poporum，并且从法国大西洋分离出了一种新的 Azadinium dalianense 菌株。检查了这两个菌株的形态。从小亚基核糖体 DNA（SSU rDNA）、大亚基核糖体 DNA（LSU rDNA）和内部转录间隔区（ITS）序列中获得了培养菌株的序列。此外，还通过从法国大西洋收集的两个推定的 Azadinium poporum 细胞的单细胞测序获得了 LSU 序列。基于串联 SSU、LSU 和 ITS 序列的分子系统发育表明，A. zhuanum 与 A. polongum 最为接近。来自地中海的法国 Azadinium poporum（地中海）和大西洋的法国 Azadinium poporum 显示出一些遗传差异，但与其他欧洲菌株一起嵌套在一个 Azadinium poporum 核糖体类型内。来自法国的 Azadinium dalianense 与该物种的中国模式株一起组成了一个分辨率很好的分支，现在由两个核糖体类型组成。使用 LC-MS/MS 对培养的 Azadinium 菌株进行了azaspiracid 分析，结果表明，地中海 Azadinium poporum 菌株产生了 AZA-2 和 AZA-2 磷酸盐，其含量为 0.44fgcell。Azadinium zhuanum 和 A. dalianense 没有产生可检测到的 AZA。本研究的结果支持了属于 Azadinium 的物种具有高度多样性和广泛分布的观点。从地中海首次记录到产生 AZA-2 的 A. poporum 表明，该物种可能是地中海贝类中 azaspiracid 污染的罪魁祸首。
