An ouabain-sensitive Na+,K(+)-ATPase in tentacles of the sea anemone Stichodactyla helianthus

Carbamazepine exposure in the sea anemones Anemonia sulcata and Actinia equina: Metabolite identification and physiological responses

Pharmaceuticals and other emerging contaminants (EC) have been increasingly detected and measured in coastal waters and large effort has been devoted to knowing the effects these substances have in coastal ecosystems. Anthozoa class is underrepresented in ecotoxicology studies despite some of their species being endangered. Anemonia sulcata and Actinia equina are species widely distributed in the Mediterranean Sea. The objectives of this work have been to evaluate the ability of these species to accumulate carbamazepine (CBZ) from water, to determine the effects of this pharmaceutical on some physiological and biochemical endpoints and to characterize the degradation routes followed by this compound in Anthozoa tissues (biotransformation) and water. Sea anemones were exposed to 1 μg L^-1 and 100 μg L^-1 of CBZ in artificial sea water in a semi-static system for 8 days. At several times small portions of the tentacles and whole organisms were taken. Ion transport (measured as NKATPase activity), energetic metabolism (measured as glucose and lactate levels) and nitrogen excretion (measured as ammonia concentration in tissues) were determined. CBZ-exposed individuals of A. sulcata and A. equina were analyzed by ultra-high-performance liquid chromatography high-resolution mass spectrometry (UHPLC-HRMS) on a quadrupole-time-of-flight (QqTOF). The structures of nine metabolites have been tentatively identified using HRMS and HRMS/MS data with the aid of the free available Medline database. The current work constitutes the first study on the identification of Cnidarian metabolites of CBZ in species of the Anthozoa class.

Differential localization of ion transporters suggests distinct cellular mechanisms for calcification and photosynthesis between two coral species

Ion transport is fundamental for multiple physiological processes, including but not limited to pH regulation, calcification, and photosynthesis. Here, we investigated ion-transporting processes in tissues from the corals Acropora yongei and Stylophora pistillata, representatives of the complex and robust clades that diverged over 250 million years ago. Antibodies against complex IV revealed that mitochondria, an essential source of ATP for energetically costly ion transporters, were abundant throughout the tissues of A. yongei. Additionally, transmission electron microscopy revealed septate junctions in all cell layers of A. yongei, as previously reported for S. pistillata, as well as evidence for transcellular vesicular transport in calicoblastic cells. Antibodies against the alpha subunit of Na(+)/K(+)-ATPase (NKA) and plasma membrane Ca(2+)-ATPase (PMCA) immunolabeled cells in the calicoblastic epithelium of both species, suggesting conserved roles in calcification. However, NKA was abundant in the apical membrane of the oral epithelium in A. yongei but not S. pistillata, while PMCA was abundant in the gastroderm of S. pistillata but not A. yongei. These differences indicate that these two coral species utilize distinct pathways to deliver ions to the sites of calcification and photosynthesis. Finally, antibodies against mammalian sodium bicarbonate cotransporters (NBC; SLC4 family) resulted in strong immunostaining in the apical membrane of oral epithelial cells and in calicoblastic cells in A. yongei, a pattern identical to NKA. Characterization of ion transport mechanisms is an essential step toward understanding the cellular mechanisms of coral physiology and will help predict how different coral species respond to environmental stress.

Effect of high ionic strength and inhibitors of H,K-ATPase on the ouabain-sensitive K-p-nitrophenylphosphatase activity in the sea anemone Stichodactyla helianthus

The ouabain-sensitive, K-stimulated p-nitrophenyl phosphatase (K-pNPPase) activity, an associated activity of the Na,K-ATPase, was assayed in tentacles of the sea anemone Stichodactyla helianthus to investigate the possibility that the sea anemone Na,K-ATPase activity is an associated activity of an H,K-ATPase. Activity was maximal at pH 6.5-7.0, decreasing only slightly in acidic medium but falling abruptly in alkaline medium to 60% of maximum at pH 7.4. The pH of maximum activity was not remarkably altered in high ionic strength medium (560 mM choline chloride), but ouabain-sensitive K-pNPPase activity of both rat and sea anemone was strongly inhibited. Inhibitors of the gastric H,K-ATPase, 100 microM omeprazole and 10 microM SCH 28080, did not inhibit the ouabain-sensitive K-pNPPase activity. Activity of the sea anemone enzyme was inhibited by 10 microM ammonium vanadate, an inhibitor of P-type ATPase, and not by 2.5 mM sodium azide, an inhibitor of both F-type and V-type ATPase. Because the sea anemone K-pNPPase activity was previously found to be more sensitive to ouabain than the Na,K-ATPase activity, K(+)-ouabain antagonism was investigated and found to be relatively muted, whereas K(+)-Na+ competition was stronger than in the rat kidney.