Drumm Kirstine, Norlin Andreas, Kim Miran, Altenburger Andreas, Juel Hansen Per
Department of Biology, University of Copenhagen, Helsingør, 3000, Denmark.
Department of Bioscience, University of Aarhus, Roskilde, 4000, Denmark.
J Eukaryot Microbiol. 2021 Apr 18:e12854. doi: 10.1111/jeu.12854.
Ciliates within the Mesodinium rubrum/Mesodinium major species complex harbor chloroplasts and other cell organelles from specific cryptophyte species. Mesodinium major was recently described, and new studies indicate that blooms of M. major are just as common as blooms of M. rubrum. Despite this, the physiology of M. major has never been studied and compared to M. rubrum. In this study, growth, food uptake, chlorophyll a and photosynthesis were measured at six different irradiances, when fed the cryptophyte, Teleaulax amphioxeia. The results show that the light compensation point for growth of M. major was significantly higher than for M. rubrum. Inorganic carbon uptake via photosynthesis contributed by far most of total carbon uptake at most irradiances, similar to M. rubrum. Mesodinium major cells contain ~four times as many chloroplast as M. rubrum leading to up to ~four times higher rates of photosynthesis. The responses of M. major to prey starvation and refeeding were also studied. Mesodinium major was well adapted to prey starvation, and 51 d without prey did not lead to mortality. Mesodinium major quickly recovered from prey starvation when refed, due to high ingestion rates of > 150 prey/predator/d.
红色中缢虫/大形中缢虫物种复合体中的纤毛虫含有来自特定隐藻物种的叶绿体和其他细胞器。大形中缢虫最近才被描述，新的研究表明，大形中缢虫的水华与红色中缢虫的水华一样常见。尽管如此，大形中缢虫的生理学从未被研究过，也未与红色中缢虫进行过比较。在本研究中，当投喂隐藻双尖泰勒藻时，在六种不同光照强度下测量了大形中缢虫的生长、食物摄取、叶绿素a和光合作用。结果表明，大形中缢虫生长的光补偿点显著高于红色中缢虫。与红色中缢虫类似，在大多数光照强度下，通过光合作用吸收的无机碳在总碳吸收中占比最大。大形中缢虫细胞中的叶绿体数量约为红色中缢虫的四倍，导致光合作用速率高达约四倍。还研究了大形中缢虫对猎物饥饿和重新投喂的反应。大形中缢虫对猎物饥饿具有良好的适应性，51天无猎物并不会导致死亡。重新投喂时，大形中缢虫能迅速从猎物饥饿状态中恢复，因为其摄食率很高，>150个猎物/捕食者/天。
