Identification and quantification of mitochondria-rich cells in transporting epithelia

Karnaky, Karl John; Degnan, Kevin J.; Garretson, Leon T.; Zadunaisky, J. A.

doi:10.1152/ajpregu.1984.246.5.r770

Cited by 25 publications

(14 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Since the high Na ϩ concentration of SW favors the driving of NHE, elevated H ϩ secretion probably promotes NH 3 diffusion via Rh proteins. In contrast to the tight nature of the gill epithelium in FW fish, junctions between ionocytes and accessory cells of SW fish are relatively leaky (16,21). Therefore, NH 4 ϩ (NH 3 ) excretion via a paracellular pathway might be another pathway in SW fish.…”

Section: Discussionmentioning

confidence: 99%

“…Some samples were then incubated overnight at 4°C with an ␣5-monoclonal antibody against the ␣-subunit of the avian Na ϩ -K ϩ -ATPase (diluted 1: 500) (Developmental Studies Hybridoma Bank, University of Iowa, Ames, IA). Others were incubated with a specific SLC9A3 (NHE3) polyclonal antibody against the C-terminus (VAPSQRAQTRPPLTAG) of the medaka NHE3 protein (diluted 1:1,000) (16). After PBS washing for 20 min, samples were further incubated in goat anti-rabbit IgG conjugated with FITC or goat anti-mouse IgG conjugated with Texas red (Jackson Immunoresearch Laboratories, West Grove, PA) for 2 h at room temperature.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Proton-facilitated ammonia excretion by ionocytes of medaka (Oryzias latipes) acclimated to seawater

Liu

Tsung

Horng

et al. 2013

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

Liu ST, Tsung L, Horng JL, Lin LY. Proton-facilitated ammonia excretion by ionocytes of medaka (Oryzias latipes) acclimated to seawater. Am J Physiol Regul Integr Comp Physiol 305: R242-R251, 2013. First published May 15, 2013 doi:10.1152/ajpregu.00047.2013.-The proton-facilitated ammonia excretion is critical for a fish's ability to excrete ammonia in freshwater. However, it remains unclear whether that mechanism is also critical for ammonia excretion in seawater (SW). Using a scanning ion-selective electrode technique (SIET) to measure H ϩ gradients, an acidic boundary layer was detected at the yolk-sac surface of SW-acclimated medaka (Oryzias latipes) larvae. The H ϩ gradient detected at the surface of ionocytes was higher than that of keratinocytes in the yolk sac. Treatment with Tricine buffer or EIPA (a NHE inhibitor) reduced the H ϩ gradient and ammonia excretion of larvae. In situ hybridization and immunochemistry showed that slc9a2 (NHE2) and slc9a3 (NHE3) were expressed in the same SW-type ionocytes. A real-time PCR analysis showed that transfer to SW downregulated branchial mRNA expressions of slc9a3 and Rhesus glycoproteins (rhcg1, rhcg2, and rhbg) but upregulated that of slc9a2. However, slc9a3, rhcg1, rhcg2, and rhbg expressions were induced by high ammonia in SW. This study suggests that SW-type ionocytes play a role in acid and ammonia excretion and that the Na ϩ /H ϩ exchanger and Rh glycoproteins are involved in the proton-facilitated ammonia excretion mechanism. mitochondrion-rich cell; gill; fish; embryos; skin AMMONIA IS A NITROGENOUS PRODUCT of amino acid metabolism. Ammonia excretion in fish is largely accomplished by their gill epithelium, which has a large surface area and a small diffusion distance. Ammonia exists as two distinct chemical species, dissolved ammonia gas (NH 3 ) and ammonium ions (NH 4 ϩ ). The conventional term, "ammonia," used in this article refers to both NH 3 and NH 4 ϩ . In freshwater (FW) fish, it is generally accepted that ammonia excretion occurs by diffusion of nonionic NH 3 down a favorable gradient across the gill epithelium (7,11,35). The excreted NH 3 can be trapped via acid secretion into the unstirred layer of water on gill surfaces. This "acidtrapping" or "proton-facilitated" mechanism maintains a favorable NH 3 gradient across the gill epithelium (35). Although phospholipid membranes are permeable to nonionic NH 3 , the existence of NH 3 channels in cell membranes provides an efficient and regulated pathway. In recent years, Rhesus glycoproteins (Rh proteins) in cell membranes of the gill and skin epithelium were found to facilitate ammonia excretion in fishes (11,12,39). The human Rh antigen on blood cells has long been associated with blood typing; however, the role of Rh proteins in ammonia transport of erythrocytes and nonerythrocytes was discovered in the past decade. The human erythroid RhAG and its nonerythroid homologues, RhBG and RhCG, were demonstrated to function as ammonia transporters or channels (31, 32). In teleosts, Nakada et al. (24) (3...

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Proton-facilitated ammonia excretion by ionocytes of medaka (Oryzias latipes) acclimated to seawater

Liu

Tsung

Horng

et al. 2013

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

show abstract

“…Studies showing a direct correlation between MRC number and Cl Ϫ currents in the opercular and jaw skin epithelia (346,454), combined with salinity-induced changes in structure and number of MRCs in fish gills (e.g., Refs. 159,348,351,580,664,683,768,859), suggested the primacy of the MRC in NaCl extrusion.…”

Section: Nacl Secretion In Marine Teleostsmentioning

confidence: 99%

The Multifunctional Fish Gill: Dominant Site of Gas Exchange, Osmoregulation, Acid-Base Regulation, and Excretion of Nitrogenous Waste

Evans¹,

Piermarini²,

Choe³

2005

Physiological Reviews

2,322

1,788

View full text Add to dashboard Cite

The fish gill is a multipurpose organ that, in addition to providing for aquatic gas exchange, plays dominant roles in osmotic and ionic regulation, acid-base regulation, and excretion of nitrogenous wastes. Thus, despite the fact that all fish groups have functional kidneys, the gill epithelium is the site of many processes that are mediated by renal epithelia in terrestrial vertebrates. Indeed, many of the pathways that mediate these processes in mammalian renal epithelial are expressed in the gill, and many of the extrinsic and intrinsic modulators of these processes are also found in fish endocrine tissues and the gill itself. The basic patterns of gill physiology were outlined over a half century ago, but modern immunological and molecular techniques are bringing new insights into this complicated system. Nevertheless, substantial questions about the evolution of these mechanisms and control remain.

show abstract

“…2-(4-dimethylaminostyryl)-1-ethylpyridium iodide (DASEPI, K & K Laboratories), a mitochondrion-specific stain, which stains only active mitochondria (18)(19)(20). After 1 hr the tissue was rinsed several times with tilapia Ringer's solution and then examined with an epifluorescent microscope (Nikon Diaphot) with a 100-W mercury light source containing a 450-490 bandpass excitation filter, a 510 chromatic beam splitter, and a 520 longwave pass filter.…”

mentioning

confidence: 99%

Calcium uptake in the skin of a freshwater teleost.

McCormick

Hasegawa

Hirano

1992

Proc. Natl. Acad. Sci. U.S.A.

128

View full text Add to dashboard Cite

The skin, particularly the opercular membrane of some teleosts, contains mitochondrion-rich "chloride" cells and has been widely used as a model to study branchial salt-extrusion mechanisms in seawater fish. Skin isolated from the operculum of the freshwater Nile tilapia (Oreochromis nilotcus) can transport Ca2' against an ionic and electrical gradient. Adaptation of Nile tilapia to a low-Ca21 environment increased the capacity ofthe opercular membrane to transport Ca2+. The density of mitochondrion-rich cells increased in parallel with Ca2' transport capacity. The results demonstrate net Ca2+ uptake by vertebrate skin and strongly implicate mitochondrion-rich cells as the site of Ca2+ uptake in fresh water.Calcium is necessary for a variety of functions in animals, including bone and scale growth, muscle contraction, transmission of nerve impulses, hormone secretion, and intracellular signaling. In animals living in fresh water, calcium can be obtained from food or from the surrounding medium. Freshwater fish have the capacity to maintain normal blood Ca2+ levels (2-4 mM) in a wide range of external Ca2+ concentrations (<0.01 mM), even when food is withheld for long periods (1-3). Although the gills (4-12) and skin (5, 13) have both been implicated as sites of Ca2`uptake in teleosts, net Ca2' uptake in isolated skin or gill tissue has not, to our knowledge, previously been demonstrated. The present study was undertaken to determine whether net Ca2' uptake occurs in fish skin in vitro and whether mitochondrion-rich (MR) cells are involved in Ca2+ uptake. MATERIALS AND METHODSThe Nile tilapia Oreochromis niloticus is an Old World cichlid endemic to the freshwater lakes of the Rift Valley of Africa. Juvenile Nile tilapia, weighing 40-60 g and previously reared in fresh water, were kept in 33-liter tanks maintained at 24 + 1°C with charcoal filtration and aeration. Fish were kept in either freshwater (FW: 0.77-1.04 mM Na+/0.54-0.58 mM Ca2+) or low-Ca2+ freshwater (LCFW: deionized water supplemented with NaCl, 0.50-0.97 mM Na+, and 0.003-0.011 mM Ca2+). Fish were maintained under experimental conditions for at least 2 weeks before sampling and were fed a maintenance ration of commercial trout chow (0.5% body weight per day). Water samples were taken intermittently from tanks containing fish to determine environmental [Na+] and [Ca2W]. Although LCFW solution contains normal, freshwater concentrations of Na+ and Cl-, it has low levels of other ions; we explicitly assume that the results obtained are due to decreased Ca2+; absence of other divalent ions does not cause morphological changes in teleost gills (14). Environmental and total plasma [Na+] and [Ca2+] were measured by atomic absorption spectrophotometry. Two-thirds of the tank volume in each group was replaced every other day. Food was withheld for 24 hr before sampling of individual fish. Fish were killed by cranial concussion and pithing and were bled from the caudal vessels into heparinized syringes. Plasma was isolated by centrifugation and sto...

show abstract

Identification and quantification of mitochondria-rich cells in transporting epithelia

Cited by 25 publications

References 0 publications

Proton-facilitated ammonia excretion by ionocytes of medaka (Oryzias latipes) acclimated to seawater

Proton-facilitated ammonia excretion by ionocytes of medaka (Oryzias latipes) acclimated to seawater

The Multifunctional Fish Gill: Dominant Site of Gas Exchange, Osmoregulation, Acid-Base Regulation, and Excretion of Nitrogenous Waste

Calcium uptake in the skin of a freshwater teleost.

Contact Info

Product

Resources

About