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The gill epithelium which comprises several types of cell faces multiple functions (O2/CO2 transfer, acid-base balance and ionic regulation). Little is known of the respective cellular localization of these functions. TEM examination of the catfish gill shows, in pavement cells, cytoplasmic vesicles and apical pits, both ornamented with studs reminiscent of(More)
A magnetic cell separation technique (MACS) was developed for isolating and characterizing peanut lectin agglutinin positive (PNA(+)) cells from rainbow trout gills. Percoll density separated mitochondria-rich (MR) cells were serially labeled with PNA-FITC and an anti-FITC antibody covalently coupled to a 50-nm iron particle and then applied to a magnetic(More)
Percoll density-gradient separation, combined with peanut lectin agglutinin (PNA) binding and magnetic bead separation, was used to separate dispersed fish gill cells into sub-populations. Functional characterization of each of the sub-populations was performed to determine which displayed acid-activated phenamil- and bafilomycin-sensitive Na(+) uptake.(More)
The Lake Magadi tilapia (Alcolapia grahami) is an unusual fish, excreting all its nitrogenous waste as urea because of its highly alkaline and buffered aquatic habitat. Here, using both physiological and molecular studies, we describe the mechanism of branchial urea excretion in this species. In vivo, repeated short-interval sampling revealed that urea(More)
Exposure of adult brown bullheads Ictalurus nebulosus (120–450 g) to environmental hypercapnia (2% carbon dioxide in air) and subsequent recovery caused transient changes in whole body net sodium flux (J net Na+ ) and net chloride flux (J net Cl- ) resulting largely from changes in whole body sodium influx (J in Na+ ) and chloride influx (J in Cl- ).(More)
Urea excretion by the gulf toadfish (Opsanus beta) has been shown in previous studies to be a highly pulsatile facilitated transport, with excretion probably occurring at the gill. The present study reports the isolation of an 1800 base pair (kb) cDNA from toadfish gill with one open reading frame putatively encoding a 475-residue protein, the toadfish urea(More)
This review examines the recent advances in our understanding of the mechanisms of ion transport and acid-base regulation in the freshwater fish gill. The application of a combination of morphological, immunocytochemical and biochemical techniques has yielded considerable insight into the field. An important mechanism for regulation of Cl- uptake/base(More)
Ion and acid-base regulating mechanisms have been studied at the fish gill for almost a century. Original models proposed for Na(+) and Cl(-) uptake, and their linkage with H(+) and HCO(3)(-) secretion have changed substantially with the development of more sophisticated physiological techniques. At the freshwater fish gill, two dominant mechanisms for(More)
To study the mechanisms of branchial acid-base regulation, Pacific spiny dogfish were infused intravenously for 24 h with either HCl (495+/- 79 micromol kg(-1) h(-1)) or NaHCO(3) (981+/-235 micromol kg(-1) h(-1)). Infusion of HCl produced a transient reduction in blood pH. Despite continued infusion of acid, pH returned to normal by 12 h. Infusion of(More)
Epithelial tissue - the sealed and polarized layer of cells that regulates transport of ions and solutes between the environment and the internal milieu - is a defining characteristic of the Eumetazoa. Sponges, the most ancient metazoan phylum, are generally believed to lack true epithelia, but their ability to occlude passage of ions has never been tested.(More)