Division of Plant Sciences, University of Dundee at the James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK.
Faculty of Science, University of Technology, Sydney, Climate Change Cluster, Ultimo, Sydney, New South Wales, 2007, Australia.
J Phycol. 2020 Dec;56(6):1377-1397. doi: 10.1111/jpy.13050. Epub 2020 Aug 14.
Photosynthetic dinoflagellates are ecologically and biogeochemically important in marine and freshwater environments. However, surprisingly little is known of how this group acquires inorganic carbon or how these diverse processes evolved. Consequently, how CO availability ultimately influences the success of dinoflagellates over space and time remains poorly resolved compared to other microalgal groups. Here we review the evidence. Photosynthetic core dinoflagellates have a Form II RuBisCO (replaced by Form IB or Form ID in derived dinoflagellates). The in vitro kinetics of the Form II RuBisCO from dinoflagellates are largely unknown, but dinoflagellates with Form II (and other) RuBisCOs have inorganic carbon concentrating mechanisms (CCMs), as indicated by in vivo internal inorganic C accumulation and affinity for external inorganic C. However, the location of the membrane(s) at which the essential active transport component(s) of the CCM occur(s) is (are) unresolved; isolation and characterization of functionally competent chloroplasts would help in this respect. Endosymbiotic Symbiodiniaceae (in Foraminifera, Acantharia, Radiolaria, Ciliata, Porifera, Acoela, Cnidaria, and Mollusca) obtain inorganic C by transport from seawater through host tissue. In corals this transport apparently provides an inorganic C concentration around the photobiont that obviates the need for photobiont CCM. This is not the case for tridacnid bivalves, medusae, or, possibly, Foraminifera. Overcoming these long-standing knowledge gaps relies on technical advances (e.g., the in vitro kinetics of Form II RuBisCO) that can functionally track the fate of inorganic C forms.
光合甲藻在海洋和淡水环境中具有重要的生态和生物地球化学意义。然而，人们对该群体如何获取无机碳以及这些多样化的过程是如何进化的知之甚少。因此，与其他微藻群体相比，CO 可用性如何最终影响甲藻在空间和时间上的成功，仍然没有得到很好的解决。在这里，我们回顾了相关证据。光合核心甲藻具有 II 型 RuBisCO（在衍生甲藻中被 I 型或 ID 型取代）。目前还不完全了解来自甲藻的 II 型 RuBisCO 的体外动力学，但具有 II 型（和其他）RuBisCO 的甲藻具有无机碳浓缩机制（CCM），这表明体内无机 C 积累和对外界无机 C 的亲和力。然而，CCM 的必需主动转运成分的膜（s）的位置（es）尚未解决；功能上有能力的叶绿体的分离和表征将有助于这方面的研究。内共生 Symbiodiniaceae（在有孔虫、刺胞动物、放射虫、纤毛虫、多孔动物、扁形动物、刺胞动物和软体动物中）通过穿过宿主组织从海水中运输来获取无机碳。在珊瑚中，这种运输显然为光养生物提供了一个周围的无机 C 浓度，从而避免了光养生物 CCM 的需要。对于三齿蛤、水母或可能的有孔虫来说，情况并非如此。克服这些长期存在的知识差距依赖于技术进步（例如，II 型 RuBisCO 的体外动力学），这些进步可以在功能上跟踪无机 C 形式的命运。
