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Branchial ionocyte organization and ion-transport protein expression in juvenile alewives acclimated to freshwater or seawater.
J Exp Biol. 2012 Feb 15; 215(Pt 4):642-52.JE

Abstract

The alewife (Alosa pseudoharengus) is a clupeid that undergoes larval and juvenile development in freshwater preceding marine habitation. The purpose of this study was to investigate osmoregulatory mechanisms in alewives that permit homeostasis in different salinities. To this end, we measured physiological, branchial biochemical and cellular responses in juvenile alewives acclimated to freshwater (0.5 p.p.t.) or seawater (35.0 p.p.t.). Plasma chloride concentration was higher in seawater-acclimated than freshwater-acclimated individuals (141 mmol l(-1) vs 134 mmol l(-1)), but the hematocrit remained unchanged. In seawater-acclimated individuals, branchial Na(+)/K(+)-ATPase (NKA) activity was higher by 75%. Western blot analysis indicated that the abundance of the NKA α-subunit and a Na(+)/K(+)/2Cl(-) cotransporter (NKCC1) were greater in seawater-acclimated individuals by 40% and 200%, respectively. NKA and NKCC1 were localized on the basolateral surface and tubular network of ionocytes in both acclimation groups. Immunohistochemical labeling for the cystic fibrosis transmembrane conductance regulator (CFTR) was restricted to the apical crypt of ionocytes in seawater-acclimated individuals, whereas sodium/hydrogen exchanger 3 (NHE3) labeling was present on the apical surface of ionocytes in both acclimation groups. Ionocytes were concentrated on the trailing edge of the gill filament, evenly distributed along the proximal 75% of the filamental axis and reduced distally. Ionocyte size and number on the gill filament were not affected by salinity; however, the number of lamellar ionocytes was significantly lower in seawater-acclimated fish. Confocal z-series reconstructions revealed that mature ionocytes in seawater-acclimated alewives occurred in multicellular complexes. These complexes might reduce paracellular Na(+) resistance, hence facilitating Na(+) extrusion in hypo-osmoregulating juvenile alewives after seaward migration.

Authors+Show Affiliations

Department of Biology, University of Massachusetts, Amherst, MA 01003, USA. achristensen@york.cuny.eduNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

22279071

Citation

Christensen, A K., et al. "Branchial Ionocyte Organization and Ion-transport Protein Expression in Juvenile Alewives Acclimated to Freshwater or Seawater." The Journal of Experimental Biology, vol. 215, no. Pt 4, 2012, pp. 642-52.
Christensen AK, Hiroi J, Schultz ET, et al. Branchial ionocyte organization and ion-transport protein expression in juvenile alewives acclimated to freshwater or seawater. J Exp Biol. 2012;215(Pt 4):642-52.
Christensen, A. K., Hiroi, J., Schultz, E. T., & McCormick, S. D. (2012). Branchial ionocyte organization and ion-transport protein expression in juvenile alewives acclimated to freshwater or seawater. The Journal of Experimental Biology, 215(Pt 4), 642-52. https://doi.org/10.1242/jeb.063057
Christensen AK, et al. Branchial Ionocyte Organization and Ion-transport Protein Expression in Juvenile Alewives Acclimated to Freshwater or Seawater. J Exp Biol. 2012 Feb 15;215(Pt 4):642-52. PubMed PMID: 22279071.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Branchial ionocyte organization and ion-transport protein expression in juvenile alewives acclimated to freshwater or seawater. AU - Christensen,A K, AU - Hiroi,J, AU - Schultz,E T, AU - McCormick,S D, PY - 2012/1/27/entrez PY - 2012/1/27/pubmed PY - 2012/6/26/medline SP - 642 EP - 52 JF - The Journal of experimental biology JO - J Exp Biol VL - 215 IS - Pt 4 N2 - The alewife (Alosa pseudoharengus) is a clupeid that undergoes larval and juvenile development in freshwater preceding marine habitation. The purpose of this study was to investigate osmoregulatory mechanisms in alewives that permit homeostasis in different salinities. To this end, we measured physiological, branchial biochemical and cellular responses in juvenile alewives acclimated to freshwater (0.5 p.p.t.) or seawater (35.0 p.p.t.). Plasma chloride concentration was higher in seawater-acclimated than freshwater-acclimated individuals (141 mmol l(-1) vs 134 mmol l(-1)), but the hematocrit remained unchanged. In seawater-acclimated individuals, branchial Na(+)/K(+)-ATPase (NKA) activity was higher by 75%. Western blot analysis indicated that the abundance of the NKA α-subunit and a Na(+)/K(+)/2Cl(-) cotransporter (NKCC1) were greater in seawater-acclimated individuals by 40% and 200%, respectively. NKA and NKCC1 were localized on the basolateral surface and tubular network of ionocytes in both acclimation groups. Immunohistochemical labeling for the cystic fibrosis transmembrane conductance regulator (CFTR) was restricted to the apical crypt of ionocytes in seawater-acclimated individuals, whereas sodium/hydrogen exchanger 3 (NHE3) labeling was present on the apical surface of ionocytes in both acclimation groups. Ionocytes were concentrated on the trailing edge of the gill filament, evenly distributed along the proximal 75% of the filamental axis and reduced distally. Ionocyte size and number on the gill filament were not affected by salinity; however, the number of lamellar ionocytes was significantly lower in seawater-acclimated fish. Confocal z-series reconstructions revealed that mature ionocytes in seawater-acclimated alewives occurred in multicellular complexes. These complexes might reduce paracellular Na(+) resistance, hence facilitating Na(+) extrusion in hypo-osmoregulating juvenile alewives after seaward migration. SN - 1477-9145 UR - https://www.unboundmedicine.com/medline/citation/22279071/Branchial_ionocyte_organization_and_ion_transport_protein_expression_in_juvenile_alewives_acclimated_to_freshwater_or_seawater_ L2 - http://jeb.biologists.org/cgi/pmidlookup?view=long&pmid=22279071 DB - PRIME DP - Unbound Medicine ER -