Uptake, distribution and elimination of ⁵⁴Mn(II) in the brown trout (Salmo trutta)

Abstract

Brown trout (Salmo trutta) were exposed to water containing 0.1 μg·L−1 (1.8 nmol·L−1) of 54Mn(II) for 1, 3, or 6 weeks. Additional trout were exposed for 3 weeks and allowed to depurate for 1 or 3 weeks. Both the uptake and the organ distribution of manganese (Mn) were determined by gamma counting and whole‐body autoradiography. Steady‐state concentration, Css, and biological half‐life, t1/2, were calculated. The whole‐body Mn concentration (1.78 μg·kg−1) reached after 6 weeks of exposure was close to Css (1.88 μg·kg−1) and t1/2 was 9.6 d. Manganese concentration in tissues followed the decreasing order liver > viscera without liver and kidney > gills > skin, fins, bones, and head excluding gills, brain, and eyes > kidney ≈ epidermal mucus > brain > eyes > muscle. Autoradiograms indicated high Mn concentrations in the pancreatic tissue, skeleton, gastrointestinal mucosa, and olfactory system. Gills, viscera, and eyes (t1/2 = 3.7 to 8.8 d) were near steady state after 6 weeks of exposure, while the other tissues were not (t1/2 = 14.6 to 26.4 d). The depuration rate of total radioactivity was relatively rapid initially as 22% of Mn content was lost during the first week, and became slower in the following 2 weeks. Participation of Mn in enzymatic activities of liver, pancreas, and gastrointestinal mucosa may explain its high uptake in these tissues, whereas accumulation in the skeleton seems to be related to bone formation. The uptake of Mn by way of olfactory system favoured its accumulation in the brain of trout. As Mn is known to be neurotoxic, we suggest this route of uptake could be of toxicological significance for fish.

Nutrition and Metabolism of Minerals in Fish

“…Manganese uptake from FW has been demonstrated from the gills and gastrointestinal tract [ 119 , 120 ]. Unlike other trace metals, the mechanisms of Mn uptake from the gills, gut, skin and other tissues and toxicity are poorly understood.…”

Cadmium disrupts behavioural and physiological responses to alarm substance in juvenile rainbow trout (Oncorhynchus mykiss)

“…Previous studies using similar waterborne Cd concentrations (1.0·µg·l -1 and 10.0·µg·l -1 for one week at approximately 40·mg·l -1 water hardness as CaCO3) have shown qualitatively that cadmium accumulates in the olfactory system of brown trout (Salmo trutta; Tjälve and Gottofrey, 1986). Furthermore, several other metals have been shown to accumulate in the olfactory system of fish (Rouleau et al, 1995(Rouleau et al, , 1999Tjälve and Henriksson, 1999). However, unlike some other metals, cadmium does not cross the blood-brain barrier or synapses in the olfactory bulb (Evans and Hastings, 1992), so does not accumulate in higher centres of the brain.…”

Multi-compartment kinetic-allometric model of radionuclide bioaccumulation in marine fish

“…Taking into account the relations ( 9)-( 10) for constant AE w and AE f , the equation ( 7) will be similar to the standard wholebody single compartment equation Rouleau et al (1995) if elimination terms in ( 7) are replaced by a single term λ wb C wb , assuming that λ wb is a single whole-body elimination rate (Fowler and Fisher, 2004).…”