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Vol. 41 No. 3, 2002
Effects of Environmental Cl- Levels on Cl- Uptake and Mitochondria-rich Cell Morphology in Gills of the Stenohaline Goldfish, Carassius auratus
Il-Chi Chang1, Tsung-Han Lee2, Hong-Chih Wu1 and Pung-Pung Hwang3,*
1Institute of Fisheries Science, National Taiwan University, Taipei, Taiwan 106
2Department of Zoology, National Chung-Hsing University, Taichung, Taiwan 402
3Institute of Zoology, Academia Sinica, Taipei, Taiwan 115
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.
Key words: Mitochondria-rich cells, Apical surface, Chloride, Uptake.
*Correspondence: Tel: 886-2-27899521. Fax: 886-2-27899576. E-mail: zophwang@ccvax.sinica.edu.tw
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