Leblond Jeffrey D, Sengco Mario R, Sickman James O, Dahmen Jeremy L, Anderson Donald M
Department of Biology, Middle Tennessee State University, Murfreesboro, 37132, USA.
J Eukaryot Microbiol. 2006 May-Jun;53(3):211-6. doi: 10.1111/j.1550-7408.2006.00097.x.
Several harmful photosynthetic dinoflagellates have been examined over past decades for unique chemical biomarker sterols. Little emphasis has been placed on important heterotrophic genera, such as Amoebophrya, an obligate, intracellular parasite of other, often harmful, dinoflagellates with the ability to control host populations naturally. Therefore, the sterol composition of Amoebophrya was examined throughout the course of an infective cycle within its host dinoflagellate, Alexandrium tamarense, with the primary intent of identifying potential sterol biomarkers. Amoebophrya possessed two primary C(27) sterols, cholesterol and cholesta-5,22Z-dien-3beta-ol (cis-22-dehydrocholesterol), which are not unique to this genus, but were found in high relative percentages that are uncommon to other genera of dinoflagellates. Because the host also possesses cholesterol as one of its major sterols, carbon-stable isotope ratio characterization of cholesterol was performed in order to determine whether it was produced by Amoebophrya or derived intact from the host. Results indicated that cholesterol was not derived intact from the host. A comparison of the sterol profile of Amoebophrya to published sterol profiles of phylogenetic relatives revealed that its sterol profile most closely resembles that of the (proto)dinoflagellate Oxyrrhis marina rather than other extant genera.
在过去几十年里，人们对几种有害的光合性甲藻进行了研究，以寻找独特的化学生物标志物甾醇。然而，对于一些重要的异养属，如阿米巴藻（Amoebophrya），却很少有人关注。阿米巴藻是一种专性细胞内寄生虫，寄生于其他通常有害的甲藻中，具有自然控制宿主种群数量的能力。因此，我们研究了阿米巴藻在其宿主塔玛亚历山大藻（Alexandrium tamarense）内整个感染周期的甾醇组成，主要目的是确定潜在的甾醇生物标志物。阿米巴藻含有两种主要的C(27)甾醇，即胆固醇和胆甾-5,22Z-二烯-3β-醇（顺式-22-脱氢胆固醇），这些甾醇并非该属所特有，但在相对含量上较高，这在其他甲藻属中并不常见。由于宿主也将胆固醇作为其主要甾醇之一，因此我们对胆固醇进行了碳稳定同位素比率表征，以确定它是由阿米巴藻产生的还是完整地从宿主中获取的。结果表明，胆固醇并非完整地从宿主中获取。将阿米巴藻的甾醇谱与已发表的系统发育相关亲属的甾醇谱进行比较后发现，其甾醇谱与（原始）甲藻尖鼻藻（Oxyrrhis marina）最为相似，而非其他现存属。
