Effect of copper on ion content in isolated mantle cells of the marine clam Mesodesma mactroides

Abstract

The effect of copper on ion content (Na(+), K(+), Ca(2+), and Cl(-)) was evaluated in isolated mantle gills of the marine clam Mesodesma mactroides. Clams were collected at the Mar Grosso Beach (São José do Norte, Rio Grande do Sul [RS], southern Brazil), cryoanesthetized, and had their mantles dissected. Mantle cells were isolated and incubated in a calcium-free phosphate solution without (control) or with Cu (CuCl(2)). Cells were exposed to Cu for 1 h (5 µM) or 3 h (2.5 and 5 µM). In cells incubated with 2.5 µM Cu, a significant decrease in intracellular Cl(-) content was observed. However, in cells incubated with 5.0 µM Cu, significant reductions in Na(+), K(+), and Cl(-) intracellular content were observed. Given the mechanisms involved in ion transport in mantle cells of the marine clam M. mactroides, the findings described here suggest that Cu exposure inhibits carbonic anhydrase and Na(+)/K(+) -ATPase activity. Also, it can be suggested that Cu is competing with Na(+) for the same mechanisms of ion transport in the cell membrane, such as the Na(+) channels and the Na(+)/K(+)/2Cl(-) cotransporter. Results from the present study also clearly indicate that processes involved in cellular anion regulation are more sensitive to Cu exposure than those associated with the cellular cation regulation. Characterization of sites for Cu accumulation and toxicity in aquatic animals is important for derivation of metal binding constants at the biotic ligand. Also, identification of the mechanism of metal toxicity is needed for modeling metal accumulation in the biotic ligand and its consequent toxicity. Therefore, the findings reported here are extremely valuable for the development of a biotic ligand model version for marine and estuarine waters.

Mechanisms of copper accumulation in isolated mantle cells of the marine clam Mesodesma mactroides

“…As previously explained [20], cells in suspension should be used within the next 5 h after isolation [26]. Therefore, in the present study, we exposed isolated cells to Cu for 1 and 3 h after isolation.…”

“…Clams (M. mactroides; length ¼ 36.4 AE 3.1 mm, width ¼ 19.6 AE 1.5 mm, height ¼ 9.3 AE 0.9 mm) were collected and acclimated to laboratory conditions as described in our companion article [20] In vivo Cu accumulation in tissues Acclimated clams (n ¼ 24) were individually exposed (for up to 96 h) to 5 mM Cu in glass beakers containing 200 ml seawater at salinity 30 ppt (Cu-exposed clams). Also, acclimated clams (n ¼ 6) were kept individually under control conditions without addition of Cu to the water (control clams).…”

“…Each cell suspension was prepared using mantle epithelium of six clams following the protocol exactly as described in our partner article [20]. As previously reported, isolated cells were resuspended in 1 ml saline solution of ionic composition similar to that of the clam hemolymph (350 mM NaCl, 9 mM KCl, 30 mM MgCl 2 , 9 mM CaCl 2 , 2 mM NaHCO 3 , pH 7.6, 208C).…”

Physiological effects of five different marine natural organic matters (NOMs) and three different metals (Cu, Pb, Zn) on early life stages of the blue mussel (Mytilus galloprovincialis)

“…In freshwater, acute metal toxicity is related to the competition for ionic binding sites in the epithelial membranes and enzymatic inhibition mainly at the gill cells of aquatic animals (Di Toro et al, 2001; Niyogi & Wood, 2004; Dudev & Lim, 2014). Similar mechanisms are thought to occur in seawater organisms, though there have been only a few mechanistic studies (Lopes et al, 2011; Martins et al, 2011; Nogueira et al, 2013; Tellis et al, 2013; Tellis et al, 2014). Copper (Cu) is considered one of the most toxic metals to aquatic organisms, and based mainly on studies with freshwater fish, it affects sodium (Na + ) transport sites (apical Na + transporters and basolateral Na + , K + -ATPase) and therefore Na + homeostasis (reviewed by Grosell, 2012).…”

Assessing the antifouling properties of cold-spray metal embedment using loading density gradients of metal particles

“…The toxicity towards marine invertebrates occurs through the direct absorption of waterborne metal ions, arguably the most toxic form of the metal (Pinho et al 2007; Thomas & Brooks 2010). The toxicity of copper is associated with the inhibition of Na + -and K + -ATPase activity, which causes imbalances in intracellular ions and the inhibition of the activity of carbonic anhydrase enzymes, while impairing gas exchange and acid-base regulation (Grosell et al 2007;Lopes et al 2011). In contrast, the toxicity of zinc is associated with the inhibition of Ca uptake, resulting in the reduction of total body Ca, causing decreases in food uptake and therefore reduced growth, and eventual death due to hypocalcaemia (Muyssen et al 2006).…”