Showing papers by "Christer Hogstrand published in 1996"
TL;DR: In this paper, adult rainbow trout, fitted with arterial catheters, were exposed to AgNO3 for 6 days at a concentration (10 μg Ag l−1, flow-through) close to the 7 day LC50 in moderately hard freshwater.
224 citations
TL;DR: In this article, the same authors performed static-renewal 168-h toxicity tests of silver nitrate (AgNO{sub 3}), silver chloride (AgCl{sub n}), and silver thiosulfate (Ag(S{sub 2}O{sub3}){sub n}) with juvenile rainbow trout (Oncorhyncus mykiss) by standard methods.
Abstract: Static-renewal 168-h toxicity tests of silver nitrate (AgNO{sub 3}), silver chloride (AgCl{sub n}), and silver thiosulfate (Ag(S{sub 2}O{sub 3}){sub n}) with juvenile rainbow trout (Oncorhyncus mykiss) were performed by standard methods. Because of low solubility of AgCl(s), bioassays for AgCl{sub n} were performed in two separate ways. In one test series, AgCl(s) was added to freshwater and in another, AgCl{sub n}(aq) was generated by adding AgNO{sub 3} to freshwater supplemented with 50 mM NaCl. Concentrations of Ag and metallothionein (MT) were analyzed in gills and livers of fish that survived the exposures. Although Ag added as AgNO{sub 3} was found to be highly toxic to rainbow trout (168-h LC50 = 9.1 {micro}g Ag L{sup {minus}1}), the toxicities of the other Ag salts were low. The 168-h LC50 for Ag(S{sub 2}O{sub 3}){sub n} was 137,000 {micro}g Ag L{sup {minus}1} and no mortality was observed in AgCl{sub n} (100,000 {micro}g Ag L{sup {minus}1}). Exposure to AgNO{sub 3}, Ag(S{sub 2}O{sub 3}){sub n}, or AgCl{sub n} caused accumulation of Ag and induction of MT. Highest Ag levels were found in livers of trout exposed to 164,000 {micro}g Ag L{sup {minus}1} as Ag(S{sub 2}O{sub 3}){sub n}. In these fish, the hepatic Ag concentration was increasedmore » 335 times from the control value. The MT levels in gills and liver increased with the water Ag concentration and the highest level of MT was found in liver of fish exposed to Ag(S{sub 2}O{sub 3}){sub n}.« less
188 citations
TL;DR: Zn2+ was found to be a potent blocker of this transporter, causing a mixed inhibitory effect on the ATP driven Ca2+ transport at a free Zn 2+ activity of 100 pM.
Abstract: The uptake mechanism of Zn2+ through the gill epithelium of freshwater rainbow trout was investigated both in intact animals and in isolated basolateral membranes Involvement of the apical Ca2+ uptake sites in Zn2+ uptake was examined in vivo by pharmacological manipulation of the apical Ca2+ permeability The apical entries of Ca2+ and Zn2+, but not Na2+ and Cl-, were inhibited by addition of La to the water Addition of 10 microM La reduced the influxes of Ca2+ and Zn2+ to 22 +/- 3 and 53 +/- 7% (mean +/- SE) of the control value, respectively Injection of CaCl2 also reduced the branchial influxes of Ca2+ and Zn2+ This treatment decreased the influx of Ca2- to 45 +/- 4% of the control level and the Zn2+ influx to 68 +/- 5% These results strongly imply that Zn2+ passes across the apical membrane of the chloride cells of the gills via the same pathway as Ca2+ The presence of an active basolateral transporter for Zn2+ was investigated in vitro on isolated basolateral membranes There was no ATP-dependent or Na2+(-)gradient driven transport of Zn2+ at physiological Zn2+ activities The same system was used to study potential effects of Zn2+ on the basolateral Ca2+(-)adenosinetri-phosphatase Zn2+ was found to be a potent blocker of this transporter, causing a mixed inhibitory effect on the ATP driven Ca2+ transport at a free Zn2+ activity of 100 pM
140 citations
TL;DR: In this paper, a linear model was developed for the relationship between exposure duration, copper accumulation, and fish weight: In (wet wt., μg) = 4.8 + 0.03 (exposure duration, days), 0.04 (whole-body copper, mg g−1 dry wt.) (P)
116 citations
TL;DR: The physiological responses of adult rainbow trout to a high level (30 000 μg l−1) of waterborne silver complexed by thiosulfate [Ag(S2O3)n−], as occurs in photoprocessing effluent, were compared with the responses to a low level of ionic Ag+ (10 μg l −1 as AgNO3).
69 citations
Journal Article•
TL;DR: It is demonstrated that, while female squirrelfish store large amounts of zinc in the liver and ovaries, the males show zinc levels that are typical for vertebrates, and oestrogen may trigger a redistribution of zinc from liver to ovaries.
Abstract: It is well known that zinc is an essential micronutrient and, as a rule, organisms keep relatively constant low levels of zinc to maintain cellular functions. The squirrelfish family (Holocentridae) is the only known exception from this rule. Squirrelfish accumulate very high concentrations of zinc in the liver. In the present study, we demonstrate that, while female squirrelfish store large amounts of zinc in the liver and ovaries, the males show zinc levels that are typical for vertebrates. The zinc content of the diet is the same in males and females, and zinc is not lost from the liver during starvation. Thus, the difference between genders in zinc storage is not dependent upon the diet. Rather, there are at least two processes that contribute to the accumulation in females. First, females possess high levels of two major zinc-binding proteins: metallothionein (MT) and a novel female-specific zinc-binding protein (FZnBP). In females, but not in males, almost all MT is present in the hepatocyte nucleus. FZnBP is exclusively found in the hepatocyte cytosol of females. Second, hepatocytes of female squirrelfish have a high capacity to transport zinc across the plasma membrane. In addition to the liver, only the gonads of females showed unusually high concentrations of zinc. Administration of exogenous oestrogen to females decreases the hepatic zinc concentration while there is a matching increase in the zinc content of the ovaries. Thus, oestrogen may trigger a redistribution of zinc from liver to ovaries. Together, our findings suggest that female squirrelfish may be uniquely adapted to detoxify zinc and to utilize it as a macronutrient for processes related to reproduction.
31 citations
TL;DR: The results indicate that the high concentrations of MT and Zn in Holocentridae liver are linked to normal physiological processes and suggest that the Holocent Ridae family may be a unique model for future studies of Zn metabolism and the function of MT.
Abstract: Recently, we found that liver of squirrelfish (Holocentrus rufus) from Bermuda contains remarkably high concentrations of metallothionein (MT) and Zn. To clarify the nature and cause of the Zn accumulation, four Holocentridae species from three genera (Neoniphon sammara, Sargocentron spiniferum, Myripristis violacea, and Myripristis murdjan) were collected from a totally different area, the Great Barrier Reef, Australia. The average hepatic Zn levels in these species ranged from 67 μg g-1 (S. spiniferum) to 1000 μg g-1 (N. sammara). The intraspecies variation in the hepatic Zn level was pronounced. In both N. sammara and M. murdjan, there was a 48-fold difference between the lowest and the highest Zn concentration. Zn accumulation was closely correlated to a dramatically elevated concentration of MT in liver. In N. sammara, which possessed the highest level of MT among the investigated species, the mean hepatic MT concentration was 19 500 μg g-1. Subcellular fractionation of the liver showed that MT was responsible for the binding of up to 74% of the hepatic Zn. The concentrations of MT and Zn in gills were low, suggesting that Zn storage in fish within this family is tissue-specific. The results further indicate that the high concentrations of MT and Zn in Holocentridae liver are linked to normal physiological processes. We suggest that the Holocentridae family may be a unique model for future studies of Zn metabolism and the function of MT.
27 citations