The property of larval cells of the scleractinian coral, <i>Acropora tenuis</i>, deduced from in vitro cultured cells

In previous studies, we have established approximately 15 cultured cell-lines derived from planula larvae of Acropora tenuis. Based on their morphology and behavior, these cells were classified into three types, flattened amorphous cells (FAmCs), vacuolated adherent cells (VAdCs), and small smooth cells (SSmCs). FAmCs include fibroblast-like cells and spherical, brilliant brown cells (BBrCs), which are transformable to each other. To examine the larval origin of the three cell types, we raised antibodies: anti-AtMLRP2 that appears to recognize FAmC, anti-AtAHNAK for BBrC, anti-AtSOMP5 and anti-AtEndoG for SSmC, and anti-AtGal and anti-AtFat4 for VAdC, respectively. Anti-AtMLRP2 antibody stained in vivo stomodeum and neuroblast-like cells embedded in larval ectoderm around the aboral pole. Anti-AtAHNAK antibody stained neuron-like and neuroblast-like cells, both of which were also stained with neuron-specific tubulin β-3 antibody. These results suggest that in vitro BBrCs and in vivo neuroblast-like cells share neuronal properties in common. Two antibodies for SSmCs, anti-AtSOMP5 and anti-AtEndoG, stained larval ectoderm cells, suggesting that SSmCs have larval ectoderm properties. Two antibodies for VAdCs, anti-AtGal and anti-AtFat4, stained larval endoderm cells, suggesting that VAdCs have larval endoderm properties. Therefore, the in vitro cell lines appear to retain properties of the stomodeum, neuroblast, ectoderm, or endoderm. Each of them may be used in future investigations to reveal cellular and molecular properties of cell types of coral larvae, such as the potential for symbiosis.