Uptake of mercury by the gills of the fresh water chinese crab Eriocheir sinensis (Milne-Edwards)

Abstract

An in vitro perfused preparation of gills isolated from the euryhaline Chinese crab Eriocheir sinensis has been used to investigate the uptake of mercury. The results show that mercury crosses the epithelio-cuticular complex of the anterior respiratory gills and of the posterior salt-transporting gills. Mercury passes down its concentration gradient and it may reasonably be concluded that the heavy metal enters the crab via diffusion. However, the mercury influx through the epithelio-cuticular complex is significantly increased when the concentration gradient of mercury is nullified by the addition of mercury to the internal perfusion medium. A mechanism such as exchange-diffusion could then be involved in the transepithelial movements of mercury in crab gills, but this remains a matter of speculation. It is also demonstrated that the metabolic inhibitor 2,4-dinitrophenol, applied in the perfusion medium, drastically and immediately inhibits the influx of mercury through the anterior gills, substantiating the idea that a mechanism requiring metabolic energy is involved in the transepithelial movements of mercury. The nature of the non-diffusional component of mercury transport remains a matter of controversy.