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Boudour-Boucheker, N., Boulo, V., Charmantier-Daures, M., Grousset, E., Anger, K., Charmantier, G., et al. (2014). Differential distribution of V-type H+-ATPase and Na+/K+-ATPase in the branchial chamber of the palaemonid shrimp Macrobrachium amazonicum. Cell and Tissue Research, 357(1), 195–206.
Résumé: V-H+-ATPase and Na+/K+-ATPase were localized in the gills and branchiostegites of M. amazonicum and the effects of salinity on the branchial chamber ultrastructure and on the localization of transporters were investigated. Gills present septal and pillar cells. In freshwater (FW), the apical surface of pillar cells is amplified by extensive evaginations associated with mitochondria. V-H+-ATPase immunofluorescence was localized in the membranes of the apical evaginations and in clustered subapical areas of pillar cells, suggesting labeling of intracellular vesicle membranes. Na+/K+-ATPase labeling was restricted to the septal cells. No difference in immunostaining was recorded for both proteins according to salinity (FW vs. 25 PSU). In the branchiostegite, both V-H+-ATPase and Na+/K+-ATPase immunofluorescence were localized in the same cells of the internal epithelium. Immunogold revealed that V-H+-ATPase was localized in apical evaginations and in electron-dense areas throughout the inner epithelium, while Na+/K+-ATPase occurred densely along the basal infoldings of the cytoplasmic membrane. Our results suggest that morphologically different cell types within the gill lamellae may also be functionally specialized. We propose that, in FW, pillar cells expressing V-H+-ATPase absorb ions (Cl-, Na+) that are transported either directly to the hemolymph space or through a junctional complex to the septal cells, which may be responsible for active Na+ delivery to the hemolymph through Na+/K+-ATPase. This suggests a functional link between septal and pillar cells in osmoregulation. When shrimps are transferred to FW, gill and branchiostegite epithelia undergo ultrastructural changes, most probably resulting from their involvement in osmoregulatory processes.
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Theuerkauff, D., Rivera-Ingraham, G. A., Roques, J. A. C., Azzopardi, L., Bertini, M., Lejeune, M., et al. (2018). Salinity Variation in a Mangrove Ecosystem: A Physiological Investigation to Assess Potential Consequences of Salinity Disturbances on Mangrove Crabs. Zool. Stud., 57, 36.
Résumé: Dimitri Theuerkauff, Georgina A. Rivera-Ingraham, Jonathan A.C. Roques, Laurence Azzopardi, Marine Bertini, Mathilde Lejeune, Emilie Farcy, Jehan-Herve Lignot, and Elliott Sucre (2018) Salinity is one of the main environmental factors determining coastal species distribution. However, in the specific case of mangrove crabs, salinity selection cannot be understood through ecological approaches alone. Yet understanding this issue is crucial in the context of mangrove conservation, since this ecosystem is often used as biofilter of (low-salinity) wastewater. Crabs are keystone species in this mangrove ecosystem and are differentially affected by salinity. We hypothesize that crab salinity selection may be partly explained by specific salinity-induced physiological constraints associated with osmoregulation, energy and redox homeostasis. To test this, the response to salinity variation was analysed in two landward mangrove crabs: the fiddler crab Tubuca urvillei, which inhabits low-salinity areas of the mangrove, and the red mangrove crab Neosarmatium meinerti, which lives in areas with higher salinity. Results confirm that both species are strong hypo-/hyper-osmoregulators that deal easily with large salinity variations. Such shifts in salinity do not induce changes in energy expenditure (measured as oxygen consumption) or in the production of reactive oxygen species. However, T. urvillei is physiologically suited to habitats with brackish water, since it presents i) high hemolymph osmolalities over a wider range of salinities and lower osmoregulatory capacity in seawater, ii) high Na+/K+-ATPase (NKA) activity in the posterior osmoregulatory gills and iii) a thicker osmoregulatory epithelium along the posterior gill lamellae. Therefore, while environmental salinity alone cannot directly explain fiddler and red mangrove crab distributions, our data suggest that salinity selection is indeed influenced by specific physiological adjustments.
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