Cadmium-binding protein (metallothionein) in carp.

Abstract

When carp (Cyprinus carpio) were exposed to 5 and 30 ppm Cd in the water, the contents of Cd-binding protein, which has low molecular weight, increased in the hepatopancreas, kidney, gills and gastrointestinal tract with the duration of exposure. This Cd-binding protein was purified from hepatopancreas, kidney, gills, and spleen of carp administered 2 mg/kg Cd (as CdCl2), intraperitoneally for 6 days. Two Cd-binding proteins were separated by DEAE-Sephadex A-25 column chromatography. These proteins had Cd-mercaptide bond, high cysteine contents (ca. 29-34%), but no aromatic amino acids or histidine. From these characteristics the Cd-binding proteins were identified as metallothionein.By using antiserum obtained from a rabbit to which carp hepatopancreas MT-II had been administered, immunological characteristics between hepatopancreas MT-I, II and kidney MT-II were studied, and a slight difference in antigenic determinant was observed among them.By immunological staining techniques with horseradish peroxidase, the localization of metallothionein was investigated. In the nontreated group, metallothionein was present in the acinar cells of hepatopancreas and renal convoluted tubules. In the Cd-treated group (2 mg/kg IP daily for 3 days), metallothionein was present in the nuclei, sinusoids, and extracellular space of hepatopancreas, in addition to the acinar cells. Carp were bred in 1 ppm Cd, 5 ppm Zn solution, and tap water for 14 days, following transfer to 15 ppm Cd solution, respectively. The survival ratio was the highest in the Zn group followed by Cd-treated and control groups. The metallothionein contents increased in hepatopancreas and kidney in the order: Zn>Cd>control group. IntroductionIt is well known that cadmium-induced renal dysfunction may be the causal substance of Itai-Itai disease. During the 1960s fish kills occurred several times following an increase in water pollution of rivers, lakes and seas in Japan. Some of those were caused by Cd. In Japan the environmental quality standard on water pollution of Cd has been established as <0.01 mg/mL. and since then the characteristics of fish MT separated from eel (5), plaice (6), staghorn sculpin (7), carp (8,9), skipjack (10), rainbow trout (11), and gibel (12) were elucidated.We studied the induction of MT in carp (Cyprinus carpio) exposed to Cd (13), separated MT from carp receiving IP injections of Cd and clarified amino acid compositions and physicochemical characteristics of these proteins (8,9). In addition we examined immunohistological localization of MT in carp organs (14), and the detoxification effect of MT to Cd toxicity (15). This paper summarizes some of the main points. Experimental and Results Induction of Cd-Binding ProteinCarp were exposed to 5.30 ppm Cd of in a total volume of 100 L in a polypropylene water tank. Two carp were killed by destruction of the medulla oblongata after 1/3, 1, 4, and 24 hr and 4, 15, and 31 days, and each organ (hepatopancreas, kidney, gill, gastrointestine, spleen, bile, and muscle) were removed. All org...

Isolation and characterization of naturally and artificially induced hepatic metallothioneins from two species of flatfish: Limanda limanda and Microstomus kitt

“…The existence of two isoforms of MT in the livers of Limanda limanda and Microstomus kitt is consistent with observations of animals from different phyla: rat (Rattus rattus) (Richard and Cousins 1977), carp (Cyprinus carpio; Kito et al 1986), trout (Salmo gairdneri; Olsson and Haux 1985), goldfish (Carassius auratus; Yamamura and Suzuki 1984) and crab (Scylla serrata; Olafson et al 1979). There are, however, a few species of teleosts for which different results have been obtained: catfish (Heteropneustesfossilis; Chatterjee and Maiti 1990), plaice (Pleuronectes platessa; Overnell and Coombs 1979) and dogfish (ScyIiorhinus canicula; Hidalgo and Flos 1986) possess only one isoform of MT, while the hepatic MT of coho salmon occurs in three isomeric forms (McCarter et al 1982).…”

“…While our results may reflect a real difference between mammals and fish, it seems more likely that the difference in the age of the two groups of fish considered (1 yr vs 3 yr) was not sufficient for the differences to become evident. Kito et al (1986) c From Olsson and Hogstrand (1987) d From Ridlington et al (1981) From Kagi and Nordberg (1979) f From Irons and Smith (1977) For untreated and Cd-injected fishes, the metals were eluted at the same two positions on the anion-exchange chromatography profiles. This suggests that the route of metal assimilation does not affect the nature of the metalbinding proteins.…”

Cadmium turnover in minnows (phoxinus phoxinus) preexposed to waterborne cadmium

“…The MT concentrations found in the gills, liver and kidney of the minnow were within the range of those reported for other fish species [5, 15,16], and Cd preexposure had no effect on the MT levels The MT content in the gills of the minnows (230 nmol/g body weight) was enough to sequester all Cd taken up from the water during the experiment (~8 0 pmol/g body weight) Nevertheless, significant levels of '@Cd were detected in non-MT Cdbinding fractions in the gills after the tracer exposure The non-MT '@Cd binding was lower in the liver and kidney than it was in the gills Other studies have also detected larger proportions of Cd in non-MT Cd-binding fractions in fish gills than in the liver and kidney after exposures to Cd [ll-131 This might explain why the fish gill is vulnerable to Cd [6, Another possible explanation for gill vulnerability is the poor ability of Cd to induce MT production in the gills The branchial MT concentration in the minnows was not altered, although the Cd concentration was increased 20fold by the Cd exposure This is in line with the findings of other studies [ 1 1, 12,16] The Cd accumulation in the liver and kidney during the experiment was not high enough to markedly increase the Cd concentration in the organs This was due to a high basal Cd concentration in the organs of the adult minnows After 1 yr of captivity, juvenile minnows, caught at the same time and location as the adult fish, showed Cd concentrations in the liver and kidney that were 10 times lower than those in the adult fish (unpublished results) The fish were fed with the same commercial fish food and were maintained under identical conditions during captivity This suggests that the high concentration of Cd in the liver and kidney of adult fish might be due to an age-dependent accumulation of Cd before capture…”

Metallothionein-2 gene from the mandarin fish Siniperca chuatsi: cDNA cloning, tissue expression, and immunohistochemical localization

“…Positive immunohistochemical staining for MTs has been reported in the liver and trunk kidney of a few species of fish, e.g., the carp and turbot (Kito et al, 1986;Amaral et al, 2002). The immunoreactivity findings in the mandarin fish are similar to those in the carp and turbot, but the extent and intensity of the immunohistochemical staining are lower in the mandarin fish.…”