Effects of Environmental Cl- Levels on Cl- Uptake and Mitochondria-rich Cell Morphology in Gills of the Stenohaline Goldfish, Carassius auratus
Il-Chi Chang, Tsung-Han Lee, Hong-Chih Wu and Pung-Pung Hwang (2002) The objective of the present study was to examine the correlation between morphological changes in gill MR cells and modulations in Cl- uptake in a stenohaline teleost. Goldfish (Carassius auratus) were acclimated to high-Cl and low-Cl artificial freshwater for 1 wk, and then the numbers of gill MR cells with different morphologies as well as whole-body Cl- influx were measured. Based on the size and ultrastructural features of the apical surface, gill MR cells in goldfish were classified into types I, II, and III. Type III MR cells display the largest apical dimension (6-9 µm); type II MR cells are of intermediate size (3-6 µm); while type I MR cells are the smallest (1-3 µm). Comparing the morphological and flux data, a positive correlation exists between enhanced Cl- influx and the appearances of type III MR cells in the low-Cl group. In contrast, fish exposed to high-Cl developed type I MR cells (1-3 µm) in the gills and showed a reduced Clinflux. These results suggest that MR cells expand their apical surface to enhance their capacity for Cl- uptake.
Keywords
Mitochondria-rich cells, Apical surface, Chloride, Uptake.
