Ultrastructure and distribution dynamics of chloride cells in tilapia larvae in fresh water and sea water

Abstract

Integumental and branchial chloride cells of tilapia larvae (Oreochromis mossambicus) were studied at the light-microscopical and ultrastructural level. Total numbers and distribution of chloride cells were quantified after immunostaining of cross sections of the entire larvae with an antibody against the alpha-subunit of Na+/K+-ATPase. The majority (66%) of Na+/K+-ATPase-immunoreactive (ir) cells, i.e. chloride cells, of freshwater tilapia larvae were located extrabranchially up to 48 h after hatching. Five days after hatching, the majority (80%) of chloride cells were found in the buccal cavity. Transfer of 24-h-old larvae to 20% sea water speeded up this process; 24 h after transfer (i.e. 48 h after hatching), the majority (59%) of chloride cells were located in the buccal cavity. The branchial chloride cell population of 24-h- and 120-h-old larvae consisted of immature, mature, apoptotic and necrotic chloride cells. However, relatively more immature chloride cells were observed in freshwater larvae (42-63%) than in (previously studied) freshwater adults (21%), illustrating the developmental state of the gills. After transfer to sea water, the incidence of degenerative chloride cells did not change. Furthermore, the incidence of immature cells had decreased and a new subtype of chloride cells, the "mitochondria-poor" cells, appeared more frequently. These mitochondria-poor chloride cells were characterised by an abundant tubular system and relatively few mitochondria, which were aligned at the border or concentrated in one part of the cytoplasm. Most of these cells did not contact the water. The function of their enhanced appearance after seawater transfer is unknown.

Mitochondria-rich cell activity in the yolk-sac membrane of tilapia(Oreochromis mossambicus) larvae acclimatized to different ambient chloride levels

“…By using Con-A-Texas-Red and Na + /K + -ATPase antibody doublelabeling, we scored the active MRCs and examined their profiles in larvae acclimated to high-or low-Clwater. In normal larvae 2-4·days after hatching, 20-24% of MR cells were Con-A positive (active), which is comparable with previous data determined by counting MRCs in contact with the water environment on tissue sections of tilapia larvae (Van Der Heijden et al, 1999). The proportion of active MRCs increased from 20% to 45% after 48-h low-Cl -acclimation but declined from 20% to 13% after high Cl -acclimation.…”

“…This method was modified from a previous report by Hiroi et al (1999), who used it to investigate MRC turnover in tilapia larvae during seawater acclimation and found that a portion of freshwater-type MRCs are able to transform to seawater-type MRCs. The vital stain DASPEI and its analogue DASPMI, which accumulate in active mitochondria, are the most common dyes used to label MRCs (Li et al, 1995;Witters et al, 1996;Rombough, 1999;Van Der Heijden et al, 1999).…”

Water calcium concentration modifies whole-body calcium uptake in sea bream larvae during short-term adaptation to altered salinities

“…Seawater-adapted larvae have more chloride cells than those in freshwater, presumably to excrete excess NaCl van der Heijden et al, 1999). As fish larvae develop, the distribution of the chloride cells changes and they become restricted to the gills in juveniles (see review by Kaneko et al, 2002;van der Heijden et al, 1999;Wales and Tytler, 1996).…”

Laser scanning cytometry and tissue microarray analysis of salinity effects on killifish chloride cells

“…Van der Heijden et al, 1999). We used this property to automatically segment and quantify CC on tissue microarrays of killifish gills using the LSC.…”