| Full text | |
| Author(s): |
McNamara, John Campbell
;
Freire, Carolina Arruda
Total Authors: 2
|
| Document type: | Journal article |
| Source: | INTEGRATIVE AND COMPARATIVE BIOLOGY; v. N/A, p. 12-pg., 2022-06-07. |
| Abstract | |
Synopsis Early marine invertebrates like the Branchiopoda began their sojourn into dilute media some 500 million years ago in the Middle Cambrian. Others like the Mollusca, Annelida, and many crustacean taxa have followed, accompanying major marine transgressions and regressions, shifting landmasses, orogenies, and glaciations. In adapting to these events and new habitats, such invertebrates acquired novel physiological abilities that attenuate the ion loss and water gain that constitute severe challenges to life in dilute media. Among these taxon-specific adaptations, selected from the subcellular to organismal levels of organization, and constituting a feasible evolutionary blueprint for invading freshwater, are reduced body permeability and surface (S) to volume (V) ratios, lowered osmotic concentrations, increased osmotic gradients, increased surface areas of interface epithelia, relocation of membrane proteins in ion-transporting cells, and augmented transport enzyme abundance, activity, and affinity. We examine these adaptations in taxa that have penetrated into freshwater, revealing diversified modifications, a consequence of distinct body plans, morpho-physiological resources, and occupation routes. Contingent on life history and reproductive strategy, numerous patterns of osmotic regulation have emerged, including intracellular isosmotic regulation in weak hyper-regulators and well-developed anisosmotic extracellular regulation in strong hyper-regulators, likely reflecting inertial adaptations to early life in an estuarine environment. In this review, we address osmoregulation in those freshwater invertebrate lineages that have successfully invaded this biotope. Our analyses show that across 66 freshwater invertebrate species from six phyla/classes that have transmuted into freshwater from the sea, hemolymph osmolalities decrease logarithmically with increasing S:V ratios. The arthropods have the highest osmolalities, from 300 to 650 mOsmoles/kg H2O in the Decapoda with 220-320 mOsmoles/kg H2O in the Insecta; osmolalities in the Annelida range from 150 to 200 mOsmoles/kg H2O, and the Mollusca showing the lowest osmolalities at 40-120 mOsmoles/kg H2O. Overall, osmolalities reach a cut-off at similar to 200 mOsmoles/kg H2O, independently of increasing S:V ratio. The ability of species with small S:V ratios to maintain large osmotic gradients is mirrored in their putatively higher Na+/K+-ATPase activities that drive ion uptake processes. Selection pressures on these morpho-physiological characteristics have led to differential osmoregulatory abilities, rendering possible the conquest of freshwater while retaining some tolerance of the ancestral medium. (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 |
| FAPESP's process: | 07/04870-9 - Adaptive physiological strategies in the Crustacea: the invasion of fresh water and the molecular and structural bases of osmoregulation |
| Grantee: | John Campbell McNamara |
| Support Opportunities: | Regular Research Grants |
| FAPESP's process: | 11/22537-0 - Macroevolutionary implications of osmotic, thermal and metabolic homeostasis in inter-tidal, neotropical crabs |
| Grantee: | John Campbell McNamara |
| Support Opportunities: | Regular Research Grants |
| FAPESP's process: | 10/17534-0 - Role of (Na,K)-ATPase in osmoregulation and excretion of ammonium ions in euryhaline crustaceans: identification and influence of FXYD2 on the regulation of gill (Na,K)-ATPase of the crab Callinectes danae |
| Grantee: | Francisco de Assis Leone |
| Support Opportunities: | Regular Research Grants |