School of Earth and Environmental Sciences, College of Natural Sciences, Seoul National University, Seoul 08826, Republic of Korea.
School of Earth and Environmental Sciences, College of Natural Sciences, Seoul National University, Seoul 08826, Republic of Korea; Advanced Institutes of Convergence Technology, Suwon, Gyeonggi-do 16229, Republic of Korea.
Harmful Algae. 2018 Dec;80:149-157. doi: 10.1016/j.hal.2018.11.007. Epub 2018 Nov 23.
The genus Gambierdiscus produces ciguatera toxins, which has led to extensive studies of this genus. Epiphytic dinoflagellate cells were isolated from coralline macroalgae collected from the coastal waters of Jeju Island, Korea, and two clonal cultures were established. The morphology of these cells was examined using light and scanning electron microscopy, and the sequences of the small subunit (SSU), large subunit (LSU), and internal transcribed spacer (ITS) region of rDNA were determined. The phylogenetic trees based on SSU, LSU (D1-D3), and LSU (D8-D10) rDNA showed the two Korean isolates forming a clade with unidentified strains named Gambierdiscus sp. type 2. This clade showed a clear divergence from the two closest clades containing of the G. caribaeus and G. carpenteri strains. Morphologically, the Korean isolates had an anteroposteriorly compressed cell shape having a smooth theca ornamentation. Growth of the Korean isolates ceased when water temperatures were <20 °C or >30 °C with an optimum at 26 °C. This temperature preference may account for why Gambierdiscus sp. type 2 has only been isolated from the temperate waters of Korea and Japan. However, the two most closely related species G. caribaeus and G. carpenteri have broader temperature ranges tolerating as high as 34-36 °C and are globally distributed. Based on these results, the Korean isolates are proposed as a new species in the genus Gambierdiscus and named Gambierdiscus jejuensis sp. nov. Furthermore, it is suggested that the unidentified strains belonging to the Gambierdiscus sp. type 2 be transferred to the new species, G. jejuensis.
属 Gambierdiscus 产生雪卡毒素，这导致了对该属的广泛研究。从韩国济州岛沿海水域采集的珊瑚藻中分离出附生甲藻细胞，并建立了两个克隆培养物。使用光镜和扫描电子显微镜检查这些细胞的形态，并确定 rDNA 的小亚基（SSU）、大亚基（LSU）和内部转录间隔区（ITS）序列。基于 SSU、LSU（D1-D3）和 LSU（D8-D10）rDNA 的系统发育树显示，两个韩国分离株与未鉴定的 Gambierdiscus sp. 2 型菌株形成一个分支。这个分支与包含 G. caribaeus 和 G. carpenteri 菌株的两个最接近的分支明显分化。形态上，韩国分离株具有前后压扁的细胞形状，具有光滑的壳纹装饰。当水温<20°C 或>30°C 时，韩国分离株的生长停止，最适温度为 26°C。这种温度偏好可能是 Gambierdiscus sp. 2 型仅从韩国和日本的温带水域分离出来的原因。然而，与 Gambierdiscus sp. 2 型关系最密切的两个物种 G. caribaeus 和 G. carpenteri 具有更宽的温度范围，可耐受高达 34-36°C，并且在全球范围内分布。基于这些结果，韩国分离株被提议为 Gambierdiscus 属的一个新种，并命名为 Gambierdiscus jejuensis sp. nov. 此外，建议将属于 Gambierdiscus sp. 2 型的未鉴定菌株转移到新种 Gambierdiscus jejuensis 中。
