Various Concentrations Of Cadmium Research Articles

A circadian clock regulates sensitivity to cadmium in Paramecium tetraurelia

The heavy metal cadmium is a dangerous environmental toxicant that can be lethal to humans and other organisms. This paper demonstrates that cadmium is lethal to the ciliated protozoan Paramecium tetraurelia and that a circadian clock modulates the sensitivity of the cells to cadmium. Various concentrations of cadmium were shown to increase the number of behavioral responses, decrease the swimming speed of cells, and generate large vacuole formation in cells prior to death. Cells were grown in either 12-h light/12-h dark or constant dark conditions exhibited a toxic response to 500 microM CdCl(2); the sensitivity of the response was found to vary with a 24-h periodicity. Cells were most sensitive to cadmium at circadian time 0 (CT0), while they were least sensitive in the early evening (CT12). This rhythm persisted even when the cells were grown in constant dark. The oscillation in cadmium sensitivity was shown to be temperature-compensated; cells grown at 18 degrees C and 28 degrees C had a similar 24-h oscillation. Finally, phase shifting experiments demonstrated a phase-dependent response to light. These data establish the criteria required for a circadian clock and demonstrate that P. tetraurelia possesses a circadian-influenced regulatory component of the cadmium toxic response. The Paramecium system is shown to be an excellent model system for the study of the effects of biological rhythms on heavy metal toxicity.

Removal of Cadmium by Myriophyllum heterophyllum Michx. and Potamogeton crispus L. and Its Effect on Pigments and Total Phenolic Compounds

In this study, cadmium biosorption by Myriophyllum heterophyllum Michx. and Potamogeton crispus L. was investigated. Although both species were found to be capable of removing cadmium from water, the performance of P. crispus was the most significant. These species were treated with 0, 4, 8, 16, 32, and 64 mg L(-1) cadmium solutions for 24, 48, 72, and 96 h, respectively. Cadmium uptake of both species was lowest at 4 mg L(-1 )and highest at 64 mg L(-1). Photosynthetic pigments and total phenolic compounds in both species were determined after exposure to various concentrations of cadmium for various times. Depending on the cadmium accumulation in both species, it was shown to decrease the level of chlorophyll a, chlorophyll b, and carotenoids (24 and 96 h). The anthocyanin concentration in P. crispus increased at all cadmium concentrations studied (0, 4, 8, 16, 32, and 64 mg L(-1)), whereas in Myriophyllum heterophyllum it increased at the lower cadmium concentrations (0, 4, and 8 mg L(-1)) but decreased at higher cadmium concentrations (16, 32, and 64 mg L(-1)), for all exposure periods. The total phenolic compound level in both species increased with cadmium concentration during the 24 and 96 h exposure periods.

Accumulation and elimination of cadmium in larval stage zebrafish following acute exposure

A number of recent studies have examined the impact of acute cadmium exposure on early zebrafish development at the morphological, cellular, and molecular levels. However, no information on the accumulation and elimination of cadmium during early life stages of zebrafish development has been available. Here we have quantified cadmium accumulation in larval zebrafish ( Danio rerio) by graphite furnace atomic absorption spectroscopy following short-term acute exposure and recovery periods. Zebrafish (80 h postfertilization) were exposed to various concentrations of cadmium (0.2, 1.0, 5.0, 25, 125 μM) for 3 h. Cadmium accumulation in larvae increased with exposure concentration. After exposure at 5.0, 25, and 125 μM cadmium, the fish were allowed to recover in freshwater for 0, 12, or 24 h. Cadmium content did not show a statistically significant decrease over the recovery period when exposed to 5.0 or 25 μM cadmium, whereas significant losses over the recovery period were observed following 125 μM exposure. These results suggest that the larval zebrafish decrease total cadmium body burden only following relatively high short-term acutely toxic exposures.

Effect of metal mixtures (Cd and Zn) on body weight in terrestrial isopods.

The aim of this study was to determine the effect of exposure to cadmium and zinc mixtures on the weight of terrestrial isopods. Experiments were conducted using uncontaminated specimens of P. laevis. The isopods were exposed to various concentrations of cadmium and zinc sulfate in single- and mixed-metal experiments. The mean weight of the unexposed isopods in the control group increased over the 6 weeks of observation. It was concluded that cadmium and zinc, administered separately, had a negative effect on the weight of P. laevis. The weight change (gain or loss) of P. laevis in the exposures to mixtures of cadmium and zinc sulfate were different from those of woodlice where Cd and Zn were administered separately. Combination of the lowest concentrations of Cd and Zn (20 and 1000 mg x kg(-1)) produced a stimulating effect compared to the control. Weight changes of the other two combinations of Cd and Zn (80/4000 and 160/8000 mg x kg(-1)) showed no differences from those of the control, and weight changes of woodlice exposed to Cd and Zn mixtures were mostly the same as those of the control over the 6-week exposure period. It can thus be concluded that mixtures of Cd and Zn have an antagonistic effect on each other in terms of weight of P. laevis.

Metal Tolerance of Scented Geranium (Pelargonium sp. ‘Frensham’): Effects of Cadmium and Nickel on Chlorophyll Fluorescence Kinetics

ABSTRACT The ability of scented geraniums (Pelargonium sp. Frensham) to tolerate metal stress was assessed using chlorophyll a fluorescence kinetics. The effects of various concentrations of cadmium and nickel in the culture solution on photosynthetic efficiency in scented geranium was evaluated in comparison to two well-established metal accumulators, the Indian mustard (Brassica juncea), and the sunflower (Helianthus annuus), under greenhouse conditions. The efficiency of the photosynthetic apparatus was affected to varying degrees at all metal concentrations for the plants tested. High concentrations of cadmium (1000 mg L-1) did not significantly affect the efficiency of photosystem II activity, expressed as the ratio of variable fluorescence to maximal fluorescence (Fv/Fm), which remained high (0.738) in scented geraniums, but decreased significantly (P < 0.05) in Indian mustard (0.089) and sunflower (0.026) plants following 4 days of metal exposure. Similar trends were observed for nickel treatments. Also, the number and size of active photosynthetic reaction centers, as measured by the Fv/Fo ratio, was not significantly affected by metal exposure in scented geranium plants, while the ratio significantly decreased in Indian mustard and sunflower seedlings. The results suggest that scented geranium plants were able to overcome metal stress through (1) maintaining an efficient photosystem II activity, which is required for plant metabolism and physiological functions, as well as to overcome metal ion mediated stress, and (2) restricting damage to the photosynthetic apparatus (reaction centers) by metal ions.

Quantitative and Qualitative Changes in Peroxidase of Cucurbita Pepo Cultivars Stressed with Heavy Metals

Seedlings of two cultivars of zucchini (Cucurbita pepo L.) Courgette d'Italie (CI) and Courgette d'Alger (CA) were pre-treated with various concentrations of cadmium, copper and zinc for 30 d. High accumulation of heavy metals especially in the roots was showed. Peroxidase activity was affected according to the type of metal added, concentration, and the plant cultivar used. In leaves and roots of the CI control plants peroxidase activities were 50 and 17 % higher than in the CA control plants. Treatment with Cd (5 µg g−1), Cu (200 µg g−1), and Zn (500 µg g−1) increased peroxidase activities in CA but decreased it in CI both in leaves and roots. Heavy metals tested lead also to some qualitative changes characterized by appearance of new isoforms of peroxidase. The results show the possibility to use the activities of peroxidase as biomarkers for Cd, Cu and Zn stresses.

The indicative value of the hsp70 stress response as a marker for metal effects in Oniscus asellus (Isopoda) field populations: variability between populations from metal-polluted and uncontaminated sites

Adult isopods ( Oniscus asellus) from two woodland sites near Heidelberg, Germany, (1) a pristine control site and (2) a site near a disused opencast mine contaminated with cadmium, lead and zinc, were exposed to various concentrations of cadmium or lead or combinations of these for three weeks under laboratory conditions. Furthermore, in a long-term semi-field mesocosm study, isopods from the control site were exposed for up to three months either to cadmium-enriched litter substrate or to heavy metal contaminated leaf litter material from the former mine. Additional isopods were sampled directly from the field at the control site and two different sites close to the mine. In each experiment, the hsp70 levels of the isopods were investigated individually by means of a standardized Western-blotting technique using monoclonal antibodies against the 70 kDa stress protein (hsp70). The studies revealed differences in the hsp70 response between the population of O. asellus living close to the mine and the population from the uncontaminated site: the latter group was characterized by a more prominent stress response to heavy metal treatment than the mine-resident population. Individuals from the control population did not acquire a physiological metal acclimatization in the mesocosm studies even after three months of exposure but resembled laboratory-exposed specimens in regards to the induction of hsp70. This observation may lead to the assumption that metal tolerance has been selected in the mine-site isopod population and, therefore, laboratory-based biomarker studies may be limited in their predicative potency in respect to long-term contaminated areas.

Short term cadmium intoxication of the shrimp Palaemon serratus: Effect on adenylate metabolism

1. 1. Shrimps were exposed for 96 hr to various concentrations of cadmium under laboratory conditions. The LC 50 was around 4 ppm Cd in water, which corresponded to 0.180 μg/g wet weight of cadmium in tail muscles. 2. 2. The effect of various concentrations of cadmium on adenylates was analyzed in tail muscles: At subletal cadmium concentrations, no variation of ATP, ADP and of the adenylate sum occurred, while the AMP concentration began to decrease from 0.06 ppm. At the LC 50, the ATP, ADP and AMP concentrations dropped acutely, the ATP/ADP ratio increased acutely. The apparent equilibrium constant of the adenylate kinase reaction increased significantly from 2 ppm Cd, indicating an impairment in energetic metabolism. Cadmium intoxication did not influence the value of the adenylate energy charge.

Secretion of human chorionic gonadotropin in superfused young placental tissue exposed to cadmium.

The effect of various concentrations of cadmium (Cd) in levels ranging from 0.75 to 12 micrograms/ml medium, on the secretion of human chorionic gonadotropin (hCG) in first-trimester placental explants, after 6 or 24 h incubation, employing both static and dynamic systems was examined. Later the unbound Cd was washed for 45 min with fresh medium devoid of Cd, followed by superfusion with the latter medium for 75 min, during which time samples were collected for hCG assay. For the superfusion experiments the parameters used for evaluating the hCG secretion pattern were: mean peak amplitude (MPA), pulse frequency (PF) and the area under the hCG secretion curve (AUC). The results indicate that in the dynamic system the hCG secretion increased significantly, and this increase was dose dependent. There was also a dose-related increase in mean total hCG secreted by the explants exposed to Cd. Maximal hCG secretion was observed after 24 h exposure of explants to 6 micrograms of the metal/ml. Both the MPA and AUC parameters showed a statistically significant increase for this dose level. At 12 micrograms/ml, the pulsatile secretion of hCG decreased, the value for the mean hCG secretion being comparable to that observed for 0.75 micrograms/ml. After 6 h incubation, however, there were no significant changes from the control, as judged by all of the above parameters. The levels of hCG secreted by the explants into the media in the static system were not significantly different from their respective controls, for both incubation periods and Cd levels. These results indicate that Cd may affect the normal placental function, as reflected in its hCG secretion pattern.

Cadmium-enhanced gene expression in suspension-culture cells of tobacco

The effects of various concentrations of cadmium on Nicotiana tabacum L. cv. Xanthi suspension cells were examined. Surprisingly, certain concentrations of Cd (100-150 μM) stimulated growth of cell cultures considerably, whereas all other concentrations were inhibitory. Synthesis of DNA was severly affected in a dose-dependent manner by Cd concentrations of 250 μM and higher. In contrast, RNA and protein synthesis were similarly stimulated by 100 μM Cd, thus indicating that enhancement of RNA synthesis was the primary cause for the observed stimulation of cell culture growth. The transient expression of a chimeric chloramphenicol-acetyltransferase gene was similarly affected by Cd. When the effects of other heavy metals (Cu, Zn, Pb, Co, Mn, Al) on these cellular processes were investigated, only Zn showed a comparable stimulation of RNA and protein synthesis, although a tenfold higher concentration of Zn compared with Cd was required. As Zn and Cd are chemically very similar, these results are discussed in view of the well-known role of Zn in the regulation of transcription.

Decrease in the mechanical strength of bones of rats administered cadmium.

The mechanical properties of the bones of young, adult and old rats administered various concentrations of cadmium were measured to prove the direct effect of cadmium on the bones of young rats. The young rats were divided into three subgroups, which were administered 0 (control), 5 and 10 ppm cadmium, respectively. The adult rats were subdivided into six groups, administered 0, 10, 20, 40, 80 and 160 ppm cadmium, respectively. The old rats were divided into three subgroups, which were administered 0, 80, and 160 ppm cadmium, respectively. The length of the administration was 4 weeks in every group. The decrease in the mechanical strengths of bones of young rats administered with cadmium was observed. On the other hand, no change in mechanical strength of bones was observed in the case of adult and old rats, administered up to 160 ppm cadmium. The correlation between the cadmium in bones and the decrease in the strength of the bone shows that cadmium directly affects the mechanical properties of bones of young rats.

Effects of heavy metals on growth and ultrastructure ofChara vulgaris

The toxicity of some heavy metals to the common macrophytic freshwater algaChara vulgaris was studied under laboratory conditions. For experiments, apical tips of algae containing two internodes were cultivated for fourteen days in the presence of various concentrations of cadmium, mercury or lead (as triethyl lead or lead nitrate). Fifty percent growth inhibition occurred with concentrations of 8.5×10−8 M (9.5 ppb) cadmium, 7.5×10−7M (150ppb) mercury, 1.6×10−6 M (330ppb) organic lead or 4× 10−5 M (8000 ppb) inorganic lead. Sublethal concentrations of these metals caused alterations in the fine structure of internodal cells which turned out to be at least partly metal-specific or in the case of lead, the effects depended on whether the lead was ionic or organically bound. Cadmium and inorganic lead induced disorders of cell wall microfibrils which resulted in local wall protuberances. Mercury affected the chloroplasts which mostly showed considerably increased grana stacks. In addition, mercury caused a dilation of the endoplasmic reticulum and of the mitochondrial tubuli. Organic lead damaged the membrane system of chloroplasts; sheet- or tubule-like thylakoids were disarranged and showed whorl-like structures. At higher concentrations of organic lead, tubular invaginations of the plasmalemma (“charasomes”) disappeared. The fine structure of nuclei was not altered by any of the metals.

Interactions of cadmium with interstitial tissue of the rat testes: Uptake of cadmium by isolated interstitial cells

Previous studies have shown that the administration of cadmium causes extensive necrosis of the testes and, eventually, a high incidence of interstitial cell tumors. However, the interactions of cadmium with interstitial cells of the testes have not been well defined. Therefore, this study was designed to assess the uptake of cadmium into this potential target cell of cadmium carcinogenesis. Interstitial cells were prepared by collagenase dispersion of decapsulated Wistar rat testes and separated from seminiferous tubules by unit gravity sedimentation. Such preparations showed a high exclusion rate of trypan blue. The interstitial cell preparations were incubated at 33° with various concentrations of cadmium (1.0 to 100μM) for periods ranging from 0.5 to 60 min. At the end of the incubation, cellular cadmium was separated from cadmium in the media by centrifugation through an oil layer. Initial experiments showed three distinct phases of cadmium influx into interstitial cells, a primary rapid velocity phase (V 0; 0 to 1.5 min), a second intermediate velocity phase (V 1; 3 to 12 min), and a third low velocity phase (V 2; 15 to 60 min). V 2 appeared to have both influx and efflux components, as efflux experiments indicated an approximate 20% loss of cadmium from 15 to 60 min. The initial phase was found to be nonsaturable and was not decreased by inclusion of potassium cyanide (1.0 mM), N-ethylmaleimide (1.0 mM), or zinc (100μM) in the incubation mixture. However, V 1 was found to be saturable between 50 and 100μM cadmium and was substantially decreased by the inclusion of potassium cyanide, N-ethylmaleimide or zinc during incubation. These data suggest that cadmium is taken up into interstitial cells by a transport system that may normally function in zinc uptake and may possibly constitute carrier mediated or active transport.

In vitro effect of cadmium on primary antibody response to T-cell independent antigen (DNP-Ficoll)

The effect of various concentrations of cadmium on the in vitro primary antibody response to T-cell independent antigen (DNP-Ficoll) was investigated. Anti DNP-Ficoll antibody response in mice was significantly enhanced by 8 μM cadmium, but suppressed by 20 and 40 μM cadmium. However, cell viabilities were decreased by cadmium exposure with dose-dependent relationships. The results suggest that in vitro exposure to cadmium produces different effects on antibody responses.

Retention of cadmium in a freshwater fish,Channa punctatus

The study revealed a significant retention of cadmium in the liver and kidney ofChanna punctatus exposed to various concentrations of cadmium. A linear relationship was observed between the period of exposure, the cadmium level in the medium and its retention in the target organs except for a sligh decline in the quantity of cadmium in the liver when exposed to 0.01 ppm concentration.

Modellierung des natürlichen Selbstreinigungsvermögens des Bodens

Connected with the elaboration of the sanitary norm of cadmium in soil were performed examinations to appoint the self-purification index. This index is the highest permissible concentration of a noxious chemical substance in soil not yet injuring irreversible the process of natural self-purification. As criterions of the self-purification were selected normal and potential respiration, quantity of bacteria, actinomyceta, fungi, proteolytic, nitrifying, and cellulolytic micro-organisms, inhibition of Bacillus subtilis and Phormidium autumnale, survival and increasing ability of Escherichia coli, Streptococcus faecalis and Salmonella give. Among the influence of various concentrations of cadmium was find out the self-purification index of 500 mg Cd++/kg. By experience are offered methodical improvements at the elaboration of self-purification indices.

Neutron Diffusion in Water Containing 1/v and Non-1/v Absorbers

Some results of a detailed study of neutron diffusion in water containing 1/v and non-1/v absorbers are reported. The Boltzmann transport equation was solved in the diffusion approximation by use of the multigroup method and the recent neutron scattering kernel proposed by the authors. The calculated values of diffusion length, L(T), in pure water in the temperature range from 0.5 to 60/sup 0/C are found to be in good agreement with most of the experimental results. (Results based on the Nelkin kernel are consistently higher.) The variation of L(T) is nonlinear up to 10/sup 0/C, but in the temperature range from 10 less than or equal to T less than or equal to 60/sup 0/C it can be expressed as L(T) = L(10/sup 0/C) + 0.00446 (T - 10). The computed values of the diffusion length in water poisoned with various concentrations of boron are consistent with the experimental results of Martinho and Costa Paiva. Fon non-1/v absorbers--cadmium and gadolinium solutions--calculations on space-dependent neutron spectra are reported. The calculated values of kappa /sub 0//sup 2/ (= 1/L/sup 2/) for various concentrations of cadmium and gadolinium are in good agreement with the experimental data of Goddard and Johnson. For high concentrationsmore » of cadmium, notable differences are observed between the present calculations and those based on the Nelkin kernel. 9 figures, 1 table.« less

The Effect of Temperature and Salinity on Cadmium Uptake by the Blue Crab, Callinectes sapidus

Adult blue crabs were exposed to various concentrations of cadmium in sea water at different thermosaline regimes. Concentration and rates of uptake of cadmium were greatest at low salinities and higher temperatres with major sites of localization in gill, hepatopancreas and carapace. Claw muscle was comparatively low in cadmium.