Department of Integrative Biology, Oregon State University, Corvallis, OR 97331, USA
Corning School of Ocean Studies, Maine Maritime Academy, Castine, ME 04420, USA.
J Exp Biol. 2020 Jul 10;223(Pt 13):jeb221424. doi: 10.1242/jeb.221424.
Carbonic anhydrases (CA; EC 4.2.1.1) play a vital role in dissolved inorganic carbon (DIC) transport to photosynthetic microalgae residing in symbiotic cnidarians. The temperate sea anemone can occur in three symbiotic states: hosting (brown), hosting (green) or without algal symbionts (aposymbiotic). This provides a basis for to be a model for detailed studies of the role of CA in DIC transport. This study investigated the effects of symbiosis, body size and light on CA activity and expression, and suggests that has a heterotrophy-dominated trophic strategy. We identified putative CA genes and performed phylogenetic analyses to infer subcellular localization in anemones. We performed experiments on field-collected anemones to compare: (1) CA activity and expression from anemones in different symbiotic states, (2) CA activity in brown anemones as a function of size, and (3) CA activity in anemones of different symbiotic states that were exposed to different light intensities. CA activity in brown anemones was highest, whereas activity in green and aposymbiotic anemones was low. Several CAs had expression patterns that mirrored activity, while another had expression that was inversely correlated with activity, suggesting that symbionts may induce different DIC transport pathways. Finally, CA activity was inversely correlated with anemone size. Our results suggest that the observed CA activity and expression patterns are affected not only by symbiosis, but also by other factors in the host physiology, including trophic strategy as it relates to body size and cellular pH homeostasis.
碳酸酐酶（CA；EC 4.2.1.1）在将溶解的无机碳（DIC）运输到共生刺胞动物中存在的光合微藻中起着至关重要的作用。温带海葵 可以存在于三种共生状态中：宿主 （棕色）、宿主 （绿色）或没有藻类共生体（无共生体）。这为 将 作为 CA 在 DIC 运输中作用的详细研究模型提供了基础。本研究调查了共生、体型和光照对 CA 活性和表达的影响，并表明 具有以异养为主的营养策略。我们鉴定了假定的 CA 基因，并进行了系统发育分析，以推断刺胞动物中 CA 的亚细胞定位。我们对野外采集的海葵进行了实验，以比较：（1）不同共生状态的海葵的 CA 活性和表达，（2）棕色海葵的 CA 活性与体型的关系，以及（3）暴露于不同光照强度下的不同共生状态的海葵的 CA 活性。棕色海葵的 CA 活性最高，而绿色和无共生体海葵的活性较低。几种 CA 的表达模式与活性相匹配，而另一种 CA 的表达与活性呈负相关，这表明共生体可能诱导不同的 DIC 运输途径。最后，CA 活性与海葵的体型呈负相关。我们的结果表明，观察到的 CA 活性和表达模式不仅受共生体的影响，还受宿主生理学中的其他因素的影响，包括与体型相关的营养策略以及细胞 pH 稳态。
