Measurements of gill protein synthesis, and hence turnover, were greatly facilitated over the last decade by the application of 'flooding dose' methodology to non-mammalian species. Numerous studies show that in fish and aquatic invertebrates, gills are among the most active tissues with respect to protein turnover, this being true under a variety of environmental and nutritional conditions. The main components being turned over in fish gills are probably collagen, primarily in the gill arches, and epithelial cell proteins in the filaments, both arches and filaments having similar protein synthesis rates. Intriguingly, differences are apparent between protein synthesis rates of adjacent holobranchs, the first (most anterior) being significantly more active than the second or third, perhaps hinting at functional differences between holobranchs. Experimental estimates of energetic costs for protein synthesis, derived from cycloheximide treatment of isolated perfused gills, give a maximum value of 14 mmol O2/g protein synthesized, which is about double theoretical costs. Environmental stressors, such as heavy metals or acid/aluminum, have variable effects on branchial protein turnover. Limited data suggest that zinc or acid exposure depresses protein synthesis, whereas acid/aluminum increases it quite markedly. Calculations indicate that whereas effects within the gilts may be substantial, in terms of whole animal energetics, the costs of branchial adaptation are likely to be small.
|Number of pages||8|
|Journal||Comparative Biochemistry and Physiology Part A: Molecular and Integrative Physiology|
|Publication status||Published - Jan 1998|
- Energetic costs
- Environmental perturbation
- Protein synthesis