Moeller Holly V, L'Etoile-Goga Amelie, Vincenzi Lucas, Norlin Andreas, Barbaglia Gina S, Runte Gabriel C, Kaare-Rasmussen Jonatan T, Johnson Matthew D
Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, Santa Barbara, California, USA.
College of Marine Sciences, University of South Florida, St. Petersburg, Florida, USA.
J Eukaryot Microbiol. 2025 Mar-Apr;72(2):e13066. doi: 10.1111/jeu.13066. Epub 2024 Nov 25.
As chloroplast-stealing or "kleptoplastidic" lineages become more reliant on stolen machinery, they also tend to become more specialized on the prey from which they acquire this machinery. For example, the ciliate Mesodinium rubrum obtains > 95% of its carbon from photosynthesis, and specializes on plastids from the Teleaulax clade of cryptophytes. However, M. rubrum is sometimes observed in nature containing plastids from other cryptophyte species. Here, we report on substantial ingestion of the blue-green cryptophyte Hemiselmis pacifica by M. rubrum, leading to organelle retention and transient increases in M. rubrum's growth rate. However, microscopy data suggest that H. pacifica organelles do not experience the same rearrangement and integration as Teleaulax amphioxeia's. We measured M. rubrum's functional response, quantified the magnitude and duration of growth benefits, and estimated kleptoplastid photosynthetic rates. Our results suggest that a lack of discrimination between H. pacifica and the preferred prey T. amphioxeia (perhaps due to similarities in cryptophyte size and swimming behavior) may result in H. pacifica ingestion Thus, while blue-green cryptophytes may represent a negligible prey source in natural environments, they may help M. rubrum survive when Teleaulax are unavailable. Furthermore, these results represent a useful tool for manipulating M. rubrum's cell biology and photophysiology.
随着窃取叶绿体或“盗食质体”的谱系越来越依赖窃取的机制，它们也往往会更加特化于获取这种机制的猎物。例如，纤毛虫红色中缢虫超过95%的碳来自光合作用，并且特化于隐藻门的泰勒藻属的质体。然而，在自然界中有时会观察到红色中缢虫含有来自其他隐藻物种的质体。在此，我们报道红色中缢虫大量摄取了蓝绿色隐藻太平洋半自养藻，导致细胞器保留以及红色中缢虫生长速率的短暂增加。然而，显微镜数据表明太平洋半自养藻的细胞器并没有经历与双尖泰勒藻相同的重排和整合。我们测量了红色中缢虫的功能反应，量化了生长益处的大小和持续时间，并估算了盗食质体的光合速率。我们的结果表明，对太平洋半自养藻和首选猎物双尖泰勒藻缺乏区分（可能是由于隐藻大小和游动行为的相似性）可能导致摄取太平洋半自养藻。因此，虽然蓝绿色隐藻在自然环境中可能是微不足道的猎物来源，但当泰勒藻不可用时，它们可能有助于红色中缢虫生存。此外，这些结果代表了一种用于操纵红色中缢虫细胞生物学和光生理学的有用工具。
