Isolation and characterization of mitochondria-rich cell types from the gill of freshwater rainbow trout.

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 column. PNA(+) MR cells were enriched to >95% purity. Transmission electron microscopy analysis of both the PNA(+) and PNA negative (PNA(-)) fraction showed that PNA binds to MR chloride cells while the PNA(-) cell fraction is comprised of MR cells with features characteristic of pavement cells. Western blotting demonstrated that both PNA(+) and PNA(-) fractions had high levels of Na(+)-K(+)-ATPase and Sco1 expression; however, relative expression of H(+)-ATPase in PNA(+) and PNA(-) cells demonstrated that untreated fish had twofold higher H(+)-ATPase levels in PNA(-) cells relative to the PNA(+) cells. Furthermore, hypercapnic acidosis significantly increased the relative H(+)-ATPase expression on PNA(-) cells only, whereas metabolic alkalosis had no significant effect.