Dinophysis spp. are mixotrophs that are dependent on specific prey, but are also potentially reliant on dissolved nutrients. The extent to which Dinophysis relies on exogenous N and the specific biochemical pathways important for supporting its autotrophic and heterotrophic growth are unknown. Here, the nutritional ecology of Dinophysis was explored using two approaches: 1) ¹⁵N tracer experiments were conducted to quantify the concentration-dependent uptake rates and associated kinetics of various N compounds (nitrate, ammonium, urea) of Dinophysis cultures and 2) the transcriptomic responses of Dinophysis cultures grown with multiple combinations of prey and nutrients were assessed via dinoflagellate spliced leader-based transcriptome profiling. Of the N compounds examined, ammonium had the highest V_max and affinity coefficient, and lowest K_s for both pre-starved and pre-fed cultures, collectively demonstrating the preference of Dinophysis for this N source while little-to-no nitrate uptake was observed. During the transcriptome experiments, Dinophysis grown with nitrate and without prey had the largest number of genes with lower transcript abundances, did not increase abundance of transcripts associated with nitrate/nitrite uptake or reduction, and displayed no cellular growth, suggesting D. acuminata is not capable of growing on nitrate. When offered prey, the transcriptomic response of Dinophysis included the production of phagolysosomes, enzymes involved in protein and lipid catabolism, and N acquisition through amino acid degradation pathways. Compared with cultures only offered ammonium or prey, cultures offered both ammonium and prey had the largest number of genes with increased transcript abundances, the highest growth rate, and the unique activation of multiple pathways involved in cellular catabolism, further evidencing the ability of Dinophysis to grow optimally as a mixotroph. Collectively, this study evidences the key role ammonium plays in the mixotrophic growth of Dinophysis and reveals the precise biochemical pathways that facilitate its mixotrophic growth.

Dinophysis spp。是取决于特定猎物的混合营养菌，但也可能依赖于溶解的营养素。Dinophysis依赖外源N的程度以及对支持其自养和异养生长至关重要的特定生化途径尚不清楚。在这里，我们使用两种方法探索了恐龙生物的营养生态学：1）进行了¹⁵ N示踪剂实验，以定量测定恐龙生物培养物中各种N化合物（硝酸盐，铵，尿素）的浓度依赖性吸收速率和相关动力学，以及2）Dinophysis的转录组反应捕食者和营养物的多种组合生长的培养物通过鞭毛藻剪接的基于领导者的转录组图谱进行评估。在所检测的N种化合物中，铵盐对于预先饥饿和喂养前的培养物均具有最高的V _max和亲和系数，并且具有最低的K _s，共同证明了Dinophysis对这种N源的偏爱，而硝酸盐的吸收几乎没有或几乎没有。观察到的。在转录组实验中，用硝酸盐生长且没有猎物的Dinophysis具有最多的转录物丰度较低的基因，没有增加与硝酸盐/亚硝酸盐吸收或还原相关的转录物的丰度，并且没有细胞生长，表明D. acuminata不能在硝酸盐上生长。当提供猎物，的转录响应鳍藻包括制作通过氨基酸降解途径参与蛋白质和脂质分解代谢，及N个采集吞噬溶酶体酶。与文化只提供铵或猎物相比，文化提供了两个铵和猎物有基因的增加成绩单丰度的数量最多，最高的增长速度，并参与细胞代谢的多种途径的独特的激活，这进一步证明了能力鳍藻到作为混合营养菌最佳生长。总的来说，这项研究能证明在的混合营养生长的关键作用铵戏剧鳍藻 并揭示了促进其混合营养生长的精确生化途径。