Evolutionary trade-offs in osmotic and ionic regulation and expression of gill ion transporter genes in high latitude, cold clime Neotropical crabs from the ?end of the world?

Author(s)

McNamara, John Campbell ; Maraschi, Anieli Cristina ; Tapella, Federico ; Romero, Maria Carolina

• Document type: Journal article
• Source: Journal of Experimental Biology; v. 226, n. 5, p. 16-pg., 2023-03-01.

Abstract

Osmoregulatory findings on crabs from high Neotropical latitudes are entirely lacking. Seeking to identify the consequences of evolution at low temperature, we examined hyperosmotic/hypo-osmotic and ionic regulation and gill ion transporter gene expression in two sub-Antarctic Eubrachyura from the Beagle Channel, Tierra del Fuego. Despite sharing the same osmotic niche, Acanthocyclus albatrossis tolerates a wider salinity range (2-65%0 S) than Halicarcinus planatus (5-60%0 S); their respective lower and upper critical salinities are 4%0 and 12%0 S, and 63%0 and 50%0 S. Acanthocyclus albatrossis is a weak hyperosmotic regulator, while H. planatus hyperosmoconforms; isosmotic points are 1380 and similar to 1340 mOsm kg-1 H2O, respectively. Both crabs hyper/hypo-regulate [Cl-] well with iso-chloride points at 452 and 316 mmol l-1 Cl-, respectively. [Na+] is hyper-regulated at all salinities. mRNA expression of gill Na*/K*-ATPase is salinity sensitive in A. albatrossis, increasing similar to 1.9-fold at 5%0 compared with 30%0 S, decreasing at 40-60%0 S. Expression in H. planatus is very low salinity sensitive, increasing similar to 4.7-fold over 30%0 S, but decreasing at 50%0 S. V-ATPase expression decreases in A. albatrossis at low and high salinities as in H. planatus. Na*/K*/ 2Cl- symporter expression in A. albatrossis increases 2.6-fold at 5%0 S, but decreases at 60%0 S versus 30%0 S. Chloride uptake may be mediated by increased Na*/K*/2Cl- expression but Cl- secretion is independent of symporter expression. These unrelated eubrachyurans exhibit similar systemic osmoregulatory characteristics and are better adapted to dilute media; however, the expression of genes underlying ion uptake and secretion shows marked interspecific divergence. Cold clime crabs may limit osmoregulatory energy expenditure by hyper/hypo-regulating hemolymph [Cl-] alone, apportioning resources for other energy-demanding processes. (AU)

• FAPESP's process: 15/00131-3 - Chloride secretion by the gill epithelium of shrimps and crabs from different osmotic niches: a physiological and molecular investigation of the Na+-K+-2Cl- symporter
• Grantee: John Campbell McNamara
• Support Opportunities: Regular Research Grants
• FAPESP's process: 13/23906-5 - The Na+, K+, 2Cl- transporter and gill chloride secretion in palaemonid shrimps (Decapoda, Crustacea): molecular, physiological and evolutionary patterns
• Grantee: Anieli Cristina Maraschi
• Support Opportunities: Scholarships in Brazil - Doctorate