Branchial NH

Abstract

Background: Cephalopods have evolved strong acid-base regulatory abilities to cope with CO 2 induced pH fluctuations in their extracellular compartments to protect gas transport via highly pH sensitive hemocyanins. To date, the mechanistic basis of branchial acid-base regulation in cephalopods is still poorly understood, and associated energetic limitations may represent a critical factor in high power squids during prolonged exposure to seawater acidification. Results: The present work used adult squid Sepioteuthis lessoniana to investigate the effects of short-term (few hours) to medium-term (up to 168 h) seawater acidification on pelagic squids. Routine metabolic rates, NH 4 + excretion, extracellular acid-base balance were monitored during exposure to control (pH 8.1) and acidified conditions of pH 7.7 and 7.3 along a period of 168 h. Metabolic rates were significantly depressed by 40% after exposure to pH 7.3 conditions for 168 h. Animals fully restored extracellular pH accompanied by an increase in blood HCO 3 − levels within 20 hours. This compensation reaction was accompanied by increased transcript abundance of branchial acid-base transporters including V-type H +-ATPase (VHA), Rhesus protein (RhP), Na + /HCO 3 − cotransporter (NBC) and cytosolic carbonic anhydrase (CAc). Immunocytochemistry demonstrated the sub-cellular localization of Na + /K +-ATPase (NKA), VHA in basolateral and Na + /H +-exchanger 3 (NHE3) and RhP in apical membranes of the ion-transporting branchial epithelium. Branchial VHA and RhP responded with increased mRNA and protein levels in response to acidified conditions indicating the importance of active NH 4 + transport to mediate acid-base balance in cephalopods. Conclusion: The present work demonstrated that cephalopods have a well developed branchial acid-base regulatory machinery. However, pelagic squids that evolved a lifestyle at the edge of energetic limits are probably more sensitive to prolonged exposure to acidified conditions compared to their more sluggish relatives including cuttlefish and octopods.

Dose-dependence and small-scale variability in responses to ocean acidification during squid, Doryteuthis pealeii, development

“…Many of the previous studies of OA and squid showed repeated significant effects on an array of variables (Lacoue-Labarthe et al 2011;Kaplan et al 2013;Hu et al 2014;Rosa et al 2014a;Navarro et al 2016). Here, we had trials that were affected by relatively high levels of pCO 2 and low pH t , but also trials that were not.…”

Resveratrol Induces Expression of Metabolic and Antioxidant Machinery and Protects Tilapia under Cold Stress

“…Oxygen consumption rates were measured approximately 24 h after the previous feeding and followed procedures modified from [52,53]. Each test subject was gently placed in a 3-L glass respiration chamber containing ultraviolet, light-sterilized, fully aerated fresh water.…”

Climate change confers a potential advantage to fleshy Antarctic crustose macroalgae over calcified species.

“…It is well understood that marine organisms have varied responses to climate change (Kroeker et al, 2011;Ries et al, 2009), including many marine algae (Harley et al, 2012;Koch et al, 2013;. Climate change will likely obscure a range of cellular to behavioral processes in many marine organisms (Dixson et al, 2010;Elettra et al, 2014;Fabry et al, 2008;Hu et al, 2014;Kelley and Hofmann, 2013). There is a significant difference between the response of calcifiers like coralline algae and non-calcifiers like 'fleshy' macroalgae, the former being most prone to negative effects of ocean acidification (Harley et al, 2012).…”