Feeding induces translocation of vacuolar proton ATPase and pendrin to the membrane of leopard shark (Triakis semifasciata) mitochondrion-rich gill cells

Abstract

In this study we characterized mitochondrion-rich (MR) cells and regulation of acid/base (A/B) relevant ion-transporting proteins in leopard shark (Triakis semifasciata) gills. Immunohistochemistry revealed that leopard shark gills posses two separate cell populations that abundantly express either Na+/K+-ATPase (NKA) or V-H+-ATPase (VHA), but not both ATPases together. Co-immunolocalization with mitochondrial Complex IV demonstrated, for the first time in shark gills, that both NKA- and VHA-rich cells are also MR cells, and that all MR cells are either NKA- or VHA-rich cells. Additionally we localized the anion exchanger pendrin to VHA-rich cells, but not NKA-rich cells. In starved sharks, VHA was localized throughout the cell cytoplasm and pendrin was present at the apical pole (but not in the membrane). However, in a significant number of gill cells from fed leopard sharks, VHA translocated to the basolateral membrane (as previously described in dogfish), and pendrin translocated to the apical membrane. Our results highlight the importance of translocation of ion-transporting proteins to the cell membrane as a regulatory mechanism for A/B regulation.

Physiological and molecular responses of the spiny dogfish shark (Squalus acanthias) to high environmental ammonia: scavenging for nitrogen

“…2) located, in contrast to teleosts. Instead, all current models for the elasmobranch gill indicate that H + -ATPase functions basolaterally in those ionocytes, which excrete base (Piermarini and Evans, 2001;Piermarini et al, 2002;Tresguerres et al, 2005;Reilly et al, 2011), so that H + ions are returned to the blood when HCO 3 -is excreted apically at times of blood alkalosis (Tresguerres et al, 2005;Tresguerres et al, 2006;Tresguerres et al, 2007;Roa et al, 2014). In the present study, there was a slight tendency towards alkalosis during HEA exposure, with a significant rise in plasma [HCO 3 -] (Fig.…”

Differential localization of ion transporters suggests distinct cellular mechanisms for calcification and photosynthesis between two coral species

“…Commercially available primary antibodies used in this study included rabbit polyclonal anti-Na ϩ /K ϩ -ATPase ␣-subunit (NKA) antibodies raised against the mammalian protein (Santa Cruz Biotechnology, Santa Cruz, CA), rabbit polyclonal antirat NBC antiserum (Chemicon International, Temecula, CA), described in (42), and the mouse monoclonal antibody (anti-OxPhos) raised against human mitochondrial complex IV, subunit 1 (Invitrogen, Carlsbad, CA). This latter antibody has been shown to specifically label mitochondria in a variety of vertebrate and invertebrate animals (e.g., 48), and in our hands, it works in paraffin-embedded shark gill samples (39). Conservation of the epitopes recognized by the antibodies used throughout animal phyla, including corals, is shown in Table 1.…”

Ammonia excretion in mytilid mussels is facilitated by ciliary beating

“…For detection of the VHA B-subunit, custom-made purified polyclonal rabbit antibodies against the peptide AREEVPGRRGFPGY were used ( protein size 55 kDA). These antibodies specifically recognize VHA B in a variety of diverse organisms including coral, bone-eating worms and sharks (Tresguerres et al, 2013;Roa et al, 2014;Barott et al, 2015). Additionally, commercially available polyclonal rabbit antibodies against mammalian α-subunit of sodium/potassium ATPase (NKA; α300, Santa Cruz Biotechnology, Dallas, TX, USA) and human carbonic anhydrase II (CA II; Rockland, Gilbertsville, PA, USA) were used recognizing proteins of the expected sizes of approximately 116 and 36 kDa, respectively.…”