Acute effects of cadmium on the spot Leiostomus xanthurus (Teleostei): tissue distribution and renal ultrastructure

Use of Arius thalassinus fish in a pollution biomonitoring study, applying combined oxidative stress, hematology, biochemical and histopathological biomarkers: A baseline field study

The present field study aimed to determine the extent of pollution in the Red Sea coast of Yemen Republic using a battery of biomarkers in sea catfish, Arius thalassinus, originating from a reference site in comparison with a polluted site. We reported the concentration of heavy metals in some vital fish organs and their effects on the morphological, hematological, biochemical and oxidative stress biomarkers accompanied by the examination of histopathological alterations. The obtained results showed clear signs of stress in fish from a polluted site. Linear correlation analysis exhibited that the biomarkers response could be linked to the detected metals bioaccumulation. In addition, principal component analysis showed a clear separation of sampling sites in two different assemblages. Semi-quantitative analysis for the observed histopathological lesions revealed that gills were the most affected organs with signs of severe alterations. This field investigation provides a baseline data on pollution status in this region.

Tissue-specific accumulation of cadmium and its effects on antioxidative responses in Japanese flounder juveniles

This study investigated the accumulation of cadmium (0-8 mg Cd L⁻¹) and its toxicological effects on oxidative stress biomarkers in different tissues of Japanese flounder juveniles. Following Cd exposure for 28 d, accumulation of Cd in fish was dose-dependent and tissue-specific, with the greatest accumulation in the liver, followed by the kidney, gill, and muscle. Although the gill and liver mounted active antioxidant responses at ≥ 4 mg L⁻¹ Cd including a decrease in glutathione level and GST and GPx activities, the antioxidant response failed to prevent lipid peroxidation induction in these organs. In the kidney, increased GPx and GST activities and decreased SOD activity were observed in fish exposed to high Cd concentrations, but LPO levels did not significantly differ among the exposure concentrations. The gill was most sensitive to oxidative damage, followed by the liver; the kidney was the least affected tissue.

Comparative study of the sensitivity to cadmium of two populations of Gambusia affinis from two different sites

This study aims to demonstrate the influence of animals' origin on their sensitivity toward heavy metals. For this purpose, we compared LC(50) of cadmium in two populations of Gambusia affinis captured in two geographically isolated environments in the east of Tunisia; Oued El Gsil in the city of Monastir (S2) and Oued Chenini in the region of Gabes (S1). Although physicochemical parameters of the water (pH, dissolved oxygen and salinity) are similar in the two studied sites, cadmium concentrations in water, sediments and fish tissues from S1 are significantly higher (P < 0.01) than those from S2, 48-h and 96-h LC(50) of the (S1) population are significantly higher than those from S2. In the same way, the offspring of the polluted site (S1) population exhibit 48-h and 96-h LC(50) values much higher than those of the reference site (S2) population. These results show that the population of the Gabes region is more resistant to cadmium than that of the Monastir region and that this resistance could have a genetic basis. These results indicate the influence of the origin of animals that has to be taken into account not only in laboratory toxicity tests, but also in field ecotoxicological studies.

Cadmium accumulation and elimination in tissues of juvenile olive flounder, Paralichthys olivaceus after sub-chronic cadmium exposure

Experiments were carried out to investigate the accumulation and elimination of cadmium (Cd) in tissues (gill, intestine, kidney, liver and muscle) of juvenile olive flounder, Paralichthys olivaceus, exposed to sub-chronic concentrations (0, 10, 50, 100 microg l(-1)) of Cd. Cd exposure resulted in an increased Cd accumulation in tissues of flounder with exposure periods and concentration, and Cd accumulation in gill and liver increased linearly with the exposure time. At 20 days of Cd exposure, the order of Cd accumulation in organs was gill > intestine > liver > kidney > muscle and after 30 days of exposure, those were intestine > gill > liver > kidney > muscle. An inverse relationship was observed between the accumulation factor (AF) and the exposure level, but AF showed an increase with exposure time. During the depuration periods, Cd concentration in the gill, intestine and liver decreased immediately following the end of the exposure periods. No significant difference was found Cd in concentration in the kidney and muscle during depuration periods. The order of Cd elimination rate in organs were decreased intestine > liver > gill during depuration periods.

Histopathological alterations of white seabass, Lates calcarifer, in acute and subchronic cadmium exposure

Histopathological alterations to white seabass, Lates calcarifer aged 3 months in acute and subchronic cadmium exposure were studied by light and scanning electron microscopy. The 96-h LC50 values of cadmium to L. calcarifer was found to be 20.12 +/- 0.61 mg/l and the maximum acceptable toxicant concentration (MATC) was 7.79 mg/l. Fish were exposed to 10 and 0.8 mg/l of Cd (as CdCl,H2O) for 96 h and 90 days, respectively. The study showed that gill lamellae and kidney tubules were the primary target organs for the acute toxic effect of cadmium while in the subchronic exposure, the toxic effect to gills was less than that of kidney and liver. Gill alterations included edema of the epithelial cells with the breakdown of pillar cell system, aneurisms with some ruptures, hypertrophy and hyperplasia of epithelial and chloride cells. The liver showed blood congestion in sinusoids and hydropic swelling of hepatocytes, vacuolation and dark granule accumulation. Lipid droplets and glycogen content were observed in hepatocytes at the second and third month of subchronic exposure. The kidney showed hydropic swelling of tubular cell vacuolation and numerous dark granule accumulation in many tubules. Tubular degeneration and necrosis were seen in some areas.

Acute toxicity effects of tributyltin chloride and triphenyltin chloride on gilthead seabream, Sparus aurata L., embryos

Acute toxicity studies, using two organotin compounds, tributyltin chloride (TBTCl) and triphenyltin chloride (TPhTCl), were performed on gilthead seabream, Sparus aurata, fertilized eggs. The tests were static and run for 24 h (temperature = 19 +/- 1 degrees C, salinity = 39.5 g/L). Three replicate egg groups were incubated in solutions containing different concentrations of the toxicants. The (24h)LC(50) value for TBTCl was 28.3 microg/L and for TPhTCl was 34.2 microg/L, when the embryos were at the morula and late blastula stage at the start of the experiment. The value for TBTCl was 38.6 microg/L, when the embryos were at the gastrula stage at the start of the experiment. The results reconfirm the expected toxicity of TBT to this euryhaline fish species and introduce TPhT as a toxicant of potentially similar impact on teleosts.

Interactions between copper and cadmium modify metal organ distribution in mature tilapia, Oreochromis mossambicus

Sexually mature female tilapia were exposed to sublethal concentrations of waterborne Cu and/or Cd over 6 days, and subsequent body concentrations of these metals were determined in several organs. The results show that the distribution of Cu and Cd was metal and organ specific. This is demonstrated, for example, by the observation that in tilapia, Cu exposure did not result in Cu accumulation in the liver, whereas in the intestinal wall, notably high concentrations of Cu and Cd were measured in metal exposed fish. In addition to single metal exposed fish, we also determined Cu and Cd body distribution in Cu?Cd co-exposed fish. The observed interactions in metal accumulation were most pronounced in the organs of fish exposed to low, environmentally realistic, metal concentrations.

Impact of cadmium on the mummichog Fundulus heteroclitus and the role of calcium in suppressing heavy metal toxicity

1. Freshwater adapted mummichogs (Fundulus heteroclitus) were exposed to cadmium. In soft water (less than or equal to 5 mg/l CaCO3), the 4-day safe (TL100) and sublethal (TL50) tolerance limits (TLs) for cadmium were 0.14 microgram/l and 12.2 micrograms/l, respectively. 2. Survival declined with increasing cadmium concentration and the length of exposure. The toxicity of cadmium was reduced in water with high calcium concentration (200 mg/l CaCO3). Pre-exposure to calcium also prolonged the survival in cadmium-containing water. 3. The mummichog appears to be extremely well suited for monitoring environmental cadmium poisoning.

Cadmium inhibition of L-alanine transport into renal brush border membrane vesicles isolated from the winter flounder (Pseudopleuronectes americanus)

Using isolated brush border membrane vesicles from the kidney of the winter flounder (Pseudopleuronectes americanus), we have studied the effect of cadmium on L-alanine transport. Pretreatment of vesicles with 0.1 mM Cd2+ resulted in inhibition of L-alanine uptake in the presence of a NaCl (but not KCl) gradient. Inhibition was due to a specific interaction with the sodium-alanine cotransport system and not a change in the driving forces for alanine transport, since Cd2+ did not affect sodium-dependent D-glucose uptake. The effect of Cd2+ on Na+-alanine cotransport showed mixed-type inhibition which is only partially reversible by EDTA. Cd2+ uptake itself was shown to be time and temperature dependent, resulting in binding to both sides of the membrane. No direct correlation was possible between inhibition of L-alanine transport and the amount of Cd2+ taken up by the membranes. Nevertheless, the striking time dependence of the effect of Cd2+ on sodium-dependent L-alanine uptake and the inability of EDTA to reverse the inhibitory action of Cd2+ suggest that Cd2+ inhibits Na+-alanine cotransport at the cytoplasmic side of the membrane.