title: Sulfur utilization of corals is enhanced by endosymbiotic algae.
abstract: Sulfur-containing compounds are important components of all organisms, but few studies have explored sulfate utilization in corals. Our previous study found that the expression of a sulfur transporter (SLC26A11) was upregulated in the presence of Symbiodinium cells in juveniles of the reef-building coral Acropora tenuis In this study, we performed autoradiography using (35)S-labeled sulfate ions ((35)SO4  (2-)) to examine the localization and amount of incorporated radioactive sulfate in the coral tissues and symbiotic algae. Incorporated (35)SO4  (2-) was detected in symbiotic algal cells, nematocysts, ectodermal cells and calicoblast cells. The combined results of (35)S autoradiography and Alcian Blue staining showed that incorporated (35)S accumulated as sulfated glycosaminoglycans (GAGs) in the ectodermal cell layer. We also compared the relative incorporation of (35)SO4  (2-) into coral tissues and endosymbiotic algae, and their chemical fractions in dark versus light (photosynthetic) conditions. The amount of sulfur compounds, such as GAGs and lipids, generated from (35)SO4  (2-) was higher under photosynthetic conditions. Together with the upregulation of sulfate transporters by symbiosis, our results suggest that photosynthesis of algal endosymbionts contributes to the synthesis and utilization of sulfur compounds in corals.
authors: Center for Information Biology, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan Graduate School of Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan.
authors: Ikuko
authors: I
authors: Yuyama
authors: Graduate School of Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan thiguchi@aori.u-tokyo.ac.jp.
authors: Tomihiko
authors: http://orcid.org/0000-0001-7324-5752
authors: T
authors: Higuchi
authors: Atmosphere and Ocean Research Institute, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8564, Japan.
authors: Yoshio
authors: Y
authors: Takei
keywords: Acropora; Coral; Endosymbiosis; Skeletogenesis; Sulfate ion; Symbiodinium