Data_Sheet_-1_RNA-Seq Analysis Reveals Genes Related to Photoreception, Nutrient Uptake, and Toxicity in a Noxious Red-Tide Raphidophyte Chattonella antiqua.xlsx

Aquaculture industries are under threat from noxious red tides, but harm can be mitigated by precautions such as early harvesting and restricting fish feeding to just before the outbreak of a red tide. Therefore, accurate techniques for forecasting red-tide outbreaks are strongly needed. Omics analyses have the potential to expand our understanding of the eco-physiology of these organisms at the molecular level, and to facilitate identification of molecular markers for forecasting their population dynamics and occurrence of damages to fisheries. Red tides of marine raphidophytes, especially Chattonella species, often extensively harm aquaculture industries in regions with a temperate climate around the world. A red tide of Chattonella tends to develop just after an input of nutrients along the coast. Chattonella displays diurnal vertical migration regulated by a weak blue light, so it photosynthesizes in the surface layer during the daytime and takes up nutrients in the bottom layer during the nighttime. Superoxide produced by Chattonella cells is a strong candidate for the cause of its toxicity to bacteria and fishes. Here we conducted mRNA-seq of Chattonella antiqua to identify genes with functions closely related to the dynamics of the noxious red tide, such as photosynthesis, photoreception, nutrient uptake, and superoxide production. The genes related to photosynthetic pigment biosynthesis and nutrient uptake had high similarity with those of model organisms of plants and algae and other red-tide microalgae. We identified orthologous genes of photoreceptors such as aureochrome (newly five genes), the cryptochrome/photolyase (CRY/PHR) family (6-4PHR, plant CRY or cyclobutane pyrimidine dimer [CPD] Class III, CPD Class II, and CRY-DASH), and phytochrome (four genes), which regulate various physiological processes such as flagellar motion and cell cycle in model organisms. Six orthologous genes of NADPH oxidase, which produces superoxide on the cell membrane, were found and divided into two types: one with 5–6 transmembrane domains and another with 11 transmembrane domains. The present study should open the way for analyzing the eco-physiological features of marine raphidophytes at the molecular level.

水产养殖业正受到有害赤潮的威胁，但可通过提前收获、仅在赤潮暴发前限制鱼类投喂等防控措施减轻危害。因此，亟需精准的赤潮暴发预报技术。组学（Omics）分析有助于从分子层面加深对这类生物生态生理学的理解，并助力鉴定用于预测其种群动态及渔业损害发生的分子标记。海洋针胞藻纲（raphidophytes）引发的赤潮，尤其是卡盾藻（Chattonella）属赤潮，常对全球温带区域的水产养殖业造成大范围损害。卡盾藻赤潮往往在沿海营养盐输入后不久暴发。卡盾藻具有受弱蓝光调控的昼夜垂直迁移行为：日间于表层水体进行光合作用，夜间则在底层水体摄取营养盐。卡盾藻细胞产生的超氧化物，是其对细菌与鱼类产生毒性的关键候选致病因子。本研究以古老卡盾藻（Chattonella antiqua）为研究对象开展mRNA测序（mRNA-seq），以鉴定与有害赤潮动态密切相关的基因，包括光合作用、光感知、营养盐摄取及超氧化物生成相关基因。与光合色素生物合成及营养盐摄取相关的基因，与植物、藻类模式生物及其他赤潮微藻的同源基因相似度较高。我们鉴定出多种光受体的直系同源基因，包括金黄素受体（aureochrome，共5个新基因）、隐花色素/光裂合酶（cryptochrome/photolyase, CRY/PHR）家族成员（涵盖6-4光裂合酶、植物隐花色素、环丁烷嘧啶二聚体[CPD] III类、CPD II类及CRY-DASH）以及光敏色素（phytochrome，共4个基因）；上述光受体在模式生物中可调控鞭毛运动、细胞周期等多种生理过程。本研究还发现6个可在细胞膜上生成超氧化物的NADPH氧化酶（NADPH oxidase）直系同源基因，可分为两类：一类含5~6个跨膜结构域，另一类含11个跨膜结构域。本研究为从分子层面解析海洋针胞藻纲的生态生理学特征开辟了全新路径。