Intracellular pH regulation in mantle epithelial cells of the Pacific oyster, Crassostrea gigas

Abstract

Shell formation and repair occurs under the control of mantle epithelial cells in bivalve molluscs. However, limited information is available on the precise acid–base regulatory machinery present within these cells, which are fundamental to calcification. Here, we isolate mantle epithelial cells from the Pacific oyster, Crassostrea gigas and utilise live cell imaging in combination with the fluorescent dye, BCECF-AM to study intracellular pH (pHi) regulation. To elucidate the involvement of various ion transport mechanisms, modified seawater solutions (low sodium, low bicarbonate) and specific inhibitors for acid–base proteins were used. Diminished pH recovery in the absence of Na+ and under inhibition of sodium/hydrogen exchangers (NHEs) implicate the involvement of a sodium dependent cellular proton extrusion mechanism. In addition, pH recovery was reduced under inhibition of carbonic anhydrases. These data provide the foundation for a better understanding of acid–base regulation underlying the physiology of calcification in bivalves.

Temperature but not ocean acidification affects energy metabolism and enzyme activities in the blue mussel, Mytilus edulis

“…In mollusks, CA plays a key role in the maintenance of acid–base homeostasis of all tissues as well as biomineralization in the mantle (Li et al., 2016; Ramesh et al., 2020; Wang et al., 2017). In M. edulis , CA activity increased with acute warming (5–35°C) in all tissues with similar E a values indicating a concerted whole‐body response of this enzyme to warming.…”

“…In mollusks, CA plays a key role in the maintenance of acid-base homeostasis of all tissues as well as biomineralization in the mantle (Li et al, 2016;Ramesh et al, 2020;Wang et al, 2017 et al, 2013). This increase is likely linked with the overall increase in metabolic rates at elevated temperatures and can assist with shell deposition.…”

“…To account for possible tissue‐specific variation in responses, we conducted a comprehensive analyses of the bioenergetic health index by measuring energy‐related biomarkers (cellular and tissue energy reserves), metabolic profiles, and specific enzyme activities (acid–base regulating enzyme and energy‐demanding ion transport enzymes) in different tissues depending on their physiological role. In mollusks, including M. edulis , carbonic anhydrase (CA) is the major acid–base regulating enzyme (Li et al., 2016; Ramesh et al., 2020; Wang et al., 2017). It plays a key role in gas exchange, acid–base regulation, calcification, and ion transport.…”

Temperature but not ocean acidification affects energy metabolism and enzyme activities in the blue mussel,Mytilus edulis

“…In mollusks, CA plays a key role in the maintenance of acid-base homeostasis of all tissues as well as biomineralization in the mantle (Li et al, 2016;Wang et al, 2017;Ramesh et al, 2020 (Ivanina et al, 2013). This increase is likely linked with the overall increase in metabolic rates at elevated temperatures and can assist with shell deposition.…”

A Bivalve Biomineralization Toolbox

“…5 ). Of the three “universal” ion transporters, one was previously identified in molluscs, the bicarbonate transporter ( Zhao et al 2018 ; Ramesh et al 2019 ; 2020 ). Bicarbonate transporters, belonging to the solute carrier 4 (SLC4) family, are involved in the transport of bicarbonate ions across the membrane and have been shown to be important in enamel development in mice ( Lacruz et al 2010 ) and calcification in corals ( Furla et al 2000 ; Bhattacharya et al 2016 ).…”