Abstract
Chasmagnathus granulatus is a hyper-hyporegulating crab that inhabits changing habitats of salinity in Brazil, Uruguay and Argentina. Since the gills are the main sites for active ion transport in crabs, the adaptive changes in the gill epithelium occurring under different conditions of salinity were studied by means of morphological and morphometric analysis, and immunohistochemical identification of cell proliferation (BrdU technique). In anterior (1–3) gills the epithelium thickness from crabs acclimatised to 12, 34 and 44 g/l ranged from 1.27 to 2.46 μm, with no significant change during acclimatisation, thus denoting a respiratory function. Medial (4–5) gill epithelium was slightly thicker in extreme salinities, but these differences were not statistically significant. In contrast, epithelial thickness of the posterior (6–8) gills increased significantly up to 8.10 μm (dorsal zone of gill 8) both in hyper- and hyposaline media compared with seawater. The dark areas measured in gill 8 treated with AgNO3 revealed putative ion transporting tissue, especially at 12 and 44 g/l, corresponding to the zones of higher epithelial thickness. Hence these areas seem to participate both in hyper- and hyporegulation. Proliferating cells labelled with BrdU almost never occurred in the gills/salinity combinations studied during the initial 48 h of transfer from seawater to hyperconcentrated or diluted media, thus suggesting an increase in cell size rather than cell proliferation.
Keywords: Ion-regulation, salinity, Crustacea
Full Text
The Full Text of this article is available as a PDF (324.9 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Barra J. A., Pequeux A., Humbert W. A morphological study on gills of a crab acclimated to fresh water. Tissue Cell. 1983;15(4):583–596. doi: 10.1016/0040-8166(83)90009-5. [DOI] [PubMed] [Google Scholar]
- Finol H. J., Croghan P. C. Ultrastructure of the branchial epithelium of an amphibious brackish-water crab. Tissue Cell. 1983;15(1):63–75. doi: 10.1016/0040-8166(83)90034-4. [DOI] [PubMed] [Google Scholar]
- Heijden A, Verbost P, Eygensteyn J, Li J, Bonga S, Flik G. Mitochondria-rich cells in gills of tilapia (Oreochromis mossambicus) adapted to fresh water or sea water: quantification by confocal laser scanning microscopy. J Exp Biol. 1997;200(Pt 1):55–64. doi: 10.1242/jeb.200.1.55. [DOI] [PubMed] [Google Scholar]
- Pierrot C., Pequeux A., Thuet P. Effects of ions substitutions and of inhibitors on transepithelial potential difference and sodium fluxes in perfused gills of the crab Pachygrapsus marmoratus. Arch Physiol Biochem. 1995 Aug;103(4):466–475. doi: 10.3109/13813459509047141. [DOI] [PubMed] [Google Scholar]