Marine Biology Department, Centre Scientifique de Monaco, 98000, Monaco.
Sorbonne Université - ED 515 Complexité du Vivant, 75005, Paris, France.
Commun Biol. 2024 Feb 29;7(1):246. doi: 10.1038/s42003-024-05938-8.
Coral reefs, the largest bioconstruction on Earth, are formed by calcium carbonate skeletons of corals. Coral skeleton formation commonly referred to as calcification occurs in a specific compartment, the extracellular calcifying medium (ECM), located between the aboral ectoderm and the skeleton. Calcification models often assume a direct link between the surrounding seawater and the ECM. However, the ECM is separated from the seawater by several tissue layers and the cœlenteron, which contains the cœlenteric fluid found in both polyps and cœnosarc (tissue connecting the polyps). Symbiotic dinoflagellate-containing cells line the cœlenteron and their photosynthetic activity contributes to changes in the chemistry of the cœlenteric fluid, particularly with respect to pH. The aim of our study is to compare cœlenteron pH between the cœnosarc and polyps and to compare areas of high or low dinoflagellate density based on tissue coloration. To achieve this, we use liquid ion exchange (LIX) pH microsensors to profile pH in the cœlenteron of polyps and the cœnosarc in different regions of the coral colony in light and darkness. We interpret our results in terms of what light and dark exposure means for proton gradients between the ECM and the coelenteron, and how this could affect calcification.
珊瑚礁是地球上最大的生物建筑，由珊瑚的碳酸钙骨骼形成。珊瑚骨骼的形成通常被称为钙化，发生在一个特定的隔室，即细胞外钙化介质（ECM），位于背侧外胚层和骨骼之间。钙化模型通常假设周围海水与 ECM 之间存在直接联系。然而，ECM 被几个组织层和腔肠隔开，腔肠中含有在水螅体和共肉（连接水螅体的组织）中都发现的腔肠液。含有共生甲藻的细胞排列在腔肠中，它们的光合作用活动导致腔肠液化学性质的变化，特别是 pH 值。我们研究的目的是比较共肉和水螅体腔肠中的腔肠 pH 值，并根据组织颜色比较高或低甲藻密度的区域。为此，我们使用液体离子交换（LIX）pH 微传感器在光和暗条件下，在珊瑚虫的腔肠中和珊瑚虫的共肉中，对珊瑚虫的不同区域的腔肠 pH 值进行分析。我们根据 ECM 和腔肠之间质子梯度的光照和黑暗暴露意味着什么，以及这如何影响钙化来解释我们的结果。
