Maternal cadmium exposure induces mt2 and smtB mRNA expression in zebrafish (Danio rerio) females and their offspring

The present study aimed to identify the effects of maternal cadmium (Cd(2+)) exposure on the mRNA expression of mt2 (metallothionein-2) and smtB (similar to metallothionein-B) in female zebrafish (Danio rerio) and their offspring (F1 larvae). Zebrafish females were exposed to 0, 8.9, 17.8, and 35.6 μM Cd(2+) for 72 h, and their ovaries and F1 larvae were collected to measure their Cd(2+) contents and their smtB and mt2 mRNA expression. Cd(2+) contents and the mRNA expression of smtB and mt2 in F1 larvae all showed positive correlations with the maternal Cd(2+) treatment dose. The mt2 was 1.9- to 3.4-fold higher than smtB in F1 larvae. Furthermore, F1 larvae had noticeably enhanced Cd(2+) tolerance after maternal Cd(2+) treatment. These results demonstrate that maternal Cd(2+) was transferred to larval fish and induced mt2 and smtB mRNA expression to protect larva against the impacts of Cd(2+). In female ovaries, mt2 expression showed a noticeable increase after exposure to a metal environment, while smtB did not show exactly the same effect. The study can only conclude that smtB might have a much different role other than just protecting against the impacts of metals.     

Cadmium removal by living cells of the marine microalga Tetraselmis suecica

Cadmium removal by living cells of the marine microalga Tetraselmis suecica was tested in cultures exposed to different cadmium concentrations (0.6, 3, 6, 15, 30 and 45 mg/l). The EC50 for growth was 7.9 mg Cd/l after six days of exposure. The cadmium removed was proportional to the concentration of this metal in the medium and it was dependent on the time of exposure; cultures with higher cadmium concentration removed a higher amount of this metal. In cultures exposed to 0.6 mg/l, T suecica cells removed 98.1% of added cadmium with 0.392 x 10(-6) microg Cd/cell, whereas in cultures with 45 mg/l only 7.7% was removed with 16.052 x 10(-6) microg Cd/cell. The highest amount of cadmium removed per liter of culture was observed in cultures exposed to 6 mg/l, with 3.577 mg/l of cadmium. After six days of incubation, the higher proportion of cadmium was bioaccumulated intracellularly in all cultures except in 45 mg/l cultures, the percentage of intracellular cadmium being always more than 50%. The highest percentage of bioadsorbed cadmium (60.1%) was found in cells of cultures with the highest cadmium concentration (45 mg/l). Furthermore, a relation between intracellular cadmium and the concentration of sulfhydryl groups was observed.     

Effect of exposure of pregnant rats to cadmium on prenatal and postnatal development of the young

Cadmium chloride in doses of 2, 12 and 40 mg Cd/kg was administered per os to pregnant rats from the 7th to 16th day of pregnancy. In another experiment female rats were exposed to cadmium oxide at a concentration of 0.02 mg Cd/m3 or 0.16 mg Cd/m3 for 5 hours a day and 5 days weekly for a period of 5 months or 1 mg Cd/m3 for 4 months. The exposure was then continued during mating and from the 1st to 20th day of pregnancy. A decrease in fertility was only observed in females exposed by inhalation to cadmium oxide at a concentration of 1 mg Cd/m3, at which concentration cadmium exhibits a considerable toxic effect on the whole organism. The young of females orally treated with CdCl2 in a dose of 40 mg Cd/kg displayed congenital defects in the form of sirenomelia or amelia, as well as raised cadmium levels in tissues. A retardation of intrauterine development manifested by lower body weight and slowed down osteogenesis was observed in the other groups. A cadmium concentration increase was not found in the tissues of the young in these groups. Inhalation exposure to 0.16 mg Cd/m3 of females prior to and during pregnancy induced in their young a decrease in viability, lower body weight gain, prolongation of latency in the negative-geotaxis test, lower locomotor activity and deteriorated development of the conditioned-reflex response. The offspring of females exposed to 0.02 mg Cd/m3 displayed lowered locomotor activity and worsened consolidation of the conditioned-reflex response.     

The applicability of acetylcholinesterase and glutathione S-transferase in Daphnia magna toxicity test

The most commonly used toxicity test worldwide is the acute Daphnia magna test. The relevance of acetylcholinesterase (AChE) and glutathione S-transferase (GST) activity in D. magna exposed to chromium, cadmium, and diazinon was evaluated in connection with this standard test. We found no link between enzyme activities and immobility. Concentrations of Cr(6+) up to 280 microg/L had no effect on AChE and GST activities, while 20% immobility was observed. At concentrations of 20-25 microg/L of Cd(2+) AChE activity was increased by about 50%. The effect of diazinon on both enzymes was insignificant up to concentrations that caused 27% immobility. Consequently, while the use of AChE and GST activities is recommended when the mode of action of chemicals is studied, the value of these biomarkers in routine acute toxicity tests is limited because the relationship between enzyme activities and immobility of D. magna exposed to different chemicals is unclear.     

Infectivity of Ornithodiplostomum ptychocheilus and Posthodiplostomum minimum (Trematoda: Diplostomidae) cercariae following exposure to cadmium

The effect of cadmium (Cd) exposure on infectivity of cercariae of 2 trematode species (Ornithodiplostomum ptychocheilus and Posthodiplostomum minimum) to their second intermediate fish host was evaluated. Individual fathead minnows (Pimephales promelas) were exposed to cercariae that had been treated with Cd solutions at concentrations of 0, 2, 20, or 200 microg/L for 2 hr. Two weeks later, the numbers of encysted metacercariae in the brain (O. ptychocheilus) and body cavity (P. minimum) of the fish were evaluated. ANOVA analyses indicated a strong negative effect of Cd concentration on cercaria infectivity. The species x Cd concentration interaction was not significant, indicating that the magnitude of Cd-induced reduction in infectivity was similar between O. ptychocheilus and P. minimum. The results show that short-term exposure to Cd, even at low concentrations, interferes with transmission processes that affect the recognition and penetration of cercariae, the migration and survival of metacercariae within the second intermediate host, or both.     

Toxicity of cadmium and zinc to Diplostomum spathaceum (Trematoda: Diplostomidae) cercarial survival

The toxicity of cadmium and zinc at concentrations ranging from 0.1 to 10000 microg/l was investigated with cercariae of Diplostomum spathaceum at three temperatures (12, 20, 25 degrees C) and three levels of water hardness (distilled water, soft water, hard water). Under most environmental conditions survival of cercariae was reduced by increasing metal concentration. Increasing water hardness and decreasing water temperature caused an increase in the survival of both control and metal exposed cercariae. However, with decreasing temperature increased survival of metal-exposed cercariae above the control occurred at a number of low metal concentrations. Differences in the relative toxicity of cadmium and zinc to cercariae was dependent on the environmental conditions of exposure. The two heavy metals demonstrated little toxicity to cercariae during the period of maximum cercarial infectivity (0-5 h).The mechanisms of metal toxicity and their effects on cercarial survival are discussed.     

Influence of parental and developmental cadmium exposure on endocrine and reproductive function in Japanese medaka (Oryzias latipes)

Cadmium (Cd) is a ubiquitous element and an important anthropogenic metal contaminant. A series of assays were modified or developed for Japanese medaka (Oryzias latipes), and used to compare the effects of Cd exposure on indicators of endocrine function in adult animals previously exposed in ovo or as hatchlings. Adults were raised either from eggs produced during a 2 week exposure to 0-10 microg/l Cd or from fry exposed for 2 weeks beginning 2 days after hatching. The reproductive capacity of the resulting adults was determined during a 2 week period during which half of the animals were re-exposed to Cd. Two week Cd exposure did not result in reproductive impairment despite producing some changes in circulating steroid concentration. In addition, 1 microg/l cadmium exposure in ovo elevated male hepatic vitellogenin (VTG) relative to controls. Hence, steroid parameters were a better biomarker of cadmium exposure than changes in VTG. However, reproductive impairment was not correlated to change in VTG or plasma steroids.     

Biosorption of cadmium and lead ions by ethanol treated waste baker's yeast biomass

The biosorption of cadmium and lead ions from artificial aqueous solutions using waste baker's yeast biomass was investigated. The yeast cells were treated with caustic, ethanol and heat for increasing their biosorption capacity and the highest metal uptake values (15.63 and 17.49 mg g(-1) for Cd(2+) and Pb(2+), respectively) were obtained by ethanol treated yeast cells. The effect of initial metal concentration and pH on biosorption by ethanol treated yeast was studied. The Langmuir model and Freundlich equation were applied to the experimental data and the Langmuir model was found to be in better correlation with the experimental data. The maximum metal uptake values (qmax, mg g(-1)) were found as 31.75 and 60.24 for Cd(2+) and Pb(2+), respectively. Competitive biosorption experiments were performed with Cd(2+) and Pb(2+) together with Cu(2+) and the competitive biosorption capacities of the yeast biomass for all metal ions were found to be lower than in non-competitive conditions.     

The use of hollow fiber cross-flow microfiltration in bioaccumulation and continuous removal of heavy metals from solution by Saccharomyces cerevisiae

Cross-flow microfiltration was shown to retain Saccharomyces cerevisiae biomass utilized for heavy metal bioaccumulation. The passage of metal-laden influent through a series of sequential bioaccumulation systems allowed for further reductions in the levels of copper, cadmium, and cobalt in the final effluent than that afforded by a single bioaccumulation process. Serial bioaccumulation systems also allowed for partial separation of metals from dual metal influents. More than one elemental metal cation could be accumulated simultaneously and in greater quantities than when a single metal was present in the effluent (Cu(2+) 0.43 mmol, Cu(2+) + Cd(2+) 0.67 mmol, and Cu(2+) + Co(2+) 0.83 mmol/g yeast dry mass when the initial concentration of each of the metal species was 0.2 mmol.L(-1)). Co-accumulation of two different metal cations allowed higher total levels of bioaccumulation than found with a single metal. The flux rate was 2.9 x 10(2) L.h(-2)mum(-2) using a polypropylene microfiltration membrane (0.1 mum pore size) at 25 degrees C. (c) 1994 John Wiley & Sons, Inc.     

镉和铅对鲫鱼肝胰脏过氧化氢酶活性的影响

采用急性毒性实验方法,研究了不同ρCd2+和ρPb2+及二者混合溶液,染毒24、48、72、96 h后,对鲫鱼肝胰脏过氧化氢酶(CAT)活性的影响.结果表明:在实验剂量范围(ρCd2+为0.5～6.0 mg/L,ρPb2+为10.0～40.0 mg/L),0.5、2.0 mg/L的Cd2+对CAT活性有诱导作用,6.0 mg/L的Cd2+对CAT活性有抑制作用;Pb2+胁迫对CAT活性随着染毒时间的延长而逐渐降低;2.0 mg/L Cd2+与20.0 mg/L Pb2+混合胁迫对CAT活性有明显的诱导作用;0.5mg/L Cd2++10.0 mg/L Pb2+,6.0 mg/L Cd2++40.0 mg/L Pb2+混合胁迫对CAT活性有明显抑制作用.Cd2+和Pb2+胁迫对CAT活性的影响呈剂量效应,二者关系曲线为抛物线,抛物线顶点是鲫鱼对Cd2+和Pb2+污染从适应到中毒反应的阈值,可间接作为检测环境污染情况的指标.     

镉对黄颡鱼鳃线粒体结构和能量代谢的影响

采用室内模拟方法,研究了重金属镉对黄颡鱼[Pelteobagrus fulvidraco (Richardson)]鳃线粒体结构和能量代谢的影响及其作用机理.结果表明,50 μg·L^-1组黄颡鱼鳃线粒体结构未受损,且各项测定指标与对照组无显著差异(P＞0.05);500 μg·L^-1组黄颡鱼鳃线粒体严重受损,除LD、MDA、ADP、AMP和血浆K⁺含量显著高于对照组外,其余检测指标均显著低于对照组(P＜0.05).高浓度镉短期暴露将降低鱼鳃线粒体SOD活性而导致线粒体氧化损伤,同时抑制PFK和ATP酶活性, 影响鳃的能量供应和利用,最终降低鳃血浆渗透压和离子浓度调节能力可能是其毒性机理之一.     

Biosorption of cadmium by biomass of marine algae

Biomass of nonliving, dried brown marine algae Sargassum natans, Fucus vesiculosus, and Ascophyllum nodosum demonstrated high equilibrium uptake of cadmium from aqueous solutions. The metal uptake of cadmium from aqueous solutions. The metal uptake by these materials was quantitatively evaluated using sorption isotherms. Biomass of A. nodosum accumulated the highest amount of cadmium exceeding 100 mg Cd(2+)/g (at the residual concentration of 100 mg Cd/L and pH 3.5), outperforming a commercial ion exchange resin DUOLITE GT-73. A new biosorbent material based on A. nodosum biomass was obtained by reinforcing the algal biomass by formaldehyde cross-linking. The prepared sorbent possessed good mechanical properties, chemical stability of the cell wall polysaccharides and low swelling volume. Desorption of deposited cadmium with 0.1-0.5M HCI resulted in no changes of the biosorbent metal uptake capacity through five subsequent adsorption/desorption cycles. There was no damage to the biosorbent which retained its macroscopic appearance and performance in repeated metal uptake/elution cycles. (c) 1993 Wiley & Sons, Inc.     

Toxic effects of cadmium and zinc on the transmission of Echinoparyphium recurvatum cercariae

The toxicity of cadmium, zinc and Cd/Zn mixtures to the transmission of Echinoparyphium recurvatum (Digenea: Echinostomatidae) cercariae into the snail second intermediate hosts was investigated at concentrations ranging from 100 microg l-1 to 10 000 microg l-1 in both soft and hard water. A differential response in the infectivity of metal-exposed cercariae into Lymnaea peregra and Physa fontinalis was demonstrated which was dependent on the snail species being infected. Exposure of L. peregra, P. fontinalis, and L. stagnalis to heavy metals caused a differing susceptibility to E. recurvatum cercariae depending on the snail species being exposed. The mechanism and effects of metal toxicity, together with the importance of the parasite/host strain on cercarial transmission are discussed.     

Metallothionein induction in early larval stages of tilapia (Oreochromis mossambicus)

Amounts of whole-body metallothionein (MT) in tilapia (Oreochromis mossambicus) larvae increased to a peak (1,500 ng mg(-1) protein) 1 d after hatching (H1), decreased rapidly thereafter, and was maintained at a constant level (700 ng mg(-1)) 3 d after hatching (H3). Waterborne Cd(2+) could stimulate MT expression in newly hatched (H0) larvae in dose-dependent and time-dependent patterns. H0 larvae, which were treated with 35 microg L(-1) Cd(2+) for 24 h, showed a 1.7-fold increase in the MT amount (174.0+/-64.7) and a 6. 5-fold increase in accumulated Cd(2+) but no significant change in Ca(2+) content, compared with the H0 control (MT, 102.6+/-48.1). H3 larvae with the same treatment revealed about a 10-fold increase in accumulated Cd(2+), a 10% decrease in Ca(2+) content, but no change in MT (261.2+/-120.0), compared with the H3 control (MT, 330+/-74.0). H0 larvae could synthesize more MT to bind Cd(2+) for detoxification in 35 microg L(-1) Cd(2+), a dose that would not affect normal physiology or survival of H0 larvae. On the other hand, 35 microg L(-1) Cd(2+) caused H3 larvae to experience hypocalcemia, an abnormal physiological condition, in which H3 larvae could not synthesize sufficient MT, thus causing greater than 25% mortality. These results indicate for the first time that the inducibility of MT by waterborne Cd(2+) is development dependent, being correlated with inconsistent sensitivities to Cd(2+) during larval development.     

Effect of Heavy Metals （Cd, Cu） on the Gametophytes of Laminaria japonica Aresch

Effects of various concentrations of two heavy metals, namely Cd and Cu, on gametophytes of Laminariajaponica Aresch were determined by recording morphological changes of gametophytes, determining pH values and the heavy metal content of the culture solution, calculating the germination rate of sporophytes, and observing heavy metal （Cd） distribution using a fluorescence microscope. The results showed that heavy metals damaged the gametophytes, and were even lethal, and that the higher the concentration of heavy metal ions, the greater the injury to gametophytes. Gametophytes could not survive in culture solutions containing more than 100 mg/L Cd and 50 mg/L Cu and were only able to survive in culture solution containing a mixture of Cd and Cu up to a concentration of 10 mg/L, which indicates that gametophytes have a higher tolerance to Cd than Cu and that multiple heavy metal ions in solution markedly aggravate the damage to gametophytes compared with individual heavy metal ions. With increases in the concentration of the heavy metal, the burgeoning rate of sporophytes decreased acutely, and solutions containing multiple heavy metal ions caused even more marked harm to sporophytes than solutions containing a single heavy metal ion, because most sporophytes died in mixed solutions. The pH value of the culture medium dropped immediately at the beginning （the first day） of treatment, increased over the following days, and then decreased again. The pH of culture media containing multiple heavy metal ions showed greater variation than media containing a single heavy metal ion, with the extent of the decrease in pH of culture media containing multiple ions being greatest during the last period of the experiment. With increases in the concentration of heavy metals, the capacity of gametophytes to accumulate these ions increased. The blue fluorescent light emitted by the Cd-and Cd-binding protein complex existing in gametophytes in media containing different concentrations of Cd showed clearly the distribution of the ion in gametophytes and the results obtained were consistent with distribution determined using other methods. All results of the present study showed that gametophytes of L. japonica play a remarkable role as heavy metal decontaminators, especially with regard to Cd.     

R-factor in Proteus vulgaris from ulcerative disease of fish,Channa punctatus

A Proteus vulgaris isolated from external ulcers of the fresh water fish Channa punctatus showed multidrug resistance and heavy metal tolerance. The isolate from the ulcer showed resistance to chloramphenicol (Ch), nalidixic acid (Nx), streptomycin (Str) and tetracycline (Tet) with minimum inhibitory concentration (MIC) values of 750, 150, 75 and 125 microg/ml, respectively. The isolate showed growth in medium containing cadmium (Cd2+), up to a concentration of 2.5 mM indicating its heavy metal tolerance. Resistance to Ch, Str, Tet and Cd2+ of the isolate was lost after plasmid curing. Presence of plasmid DNA in the wild type and its absence in the cured P. vulgaris suggested that the resistance were plasmid mediated.     

Effect of Heavy Metals (Cd, Cu) on the Gametophytes of Laminaria japonica Aresch

Effects of various concentrations of two heavy metals, namely Cd and Cu, on gametophytes of Laminariajaponica Aresch were determined by recording morphological changes of gametophytes, determining pH values and the heavy metal content of the culture solution, calculating the germination rate of sporophytes, and observing heavy metal (Cd) distribution using a fluorescence microscope. The results showed that heavy metals damaged the gametophytes, and were even lethal, and that the higher the concentration of heavy metal ions, the greater the injury to gametophytes. Gametophytes could not survive in culture solutions containing more than 100 mg/L Cd and 50 mg/L Cu and were only able to survive in culture solution containing a mixture of Cd and Cu up to a concentration of 10 mg/L, which indicates that gametophytes have a higher tolerance to Cd than Cu and that multiple heavy metal ions in solution markedly aggravate the damage to gametophytes compared with individual heavy metal ions. With increases in the concentration of the heavy metal, the burgeoning rate of sporophytes decreased acutely, and solutions containing multiple heavy metal ions caused even more marked harm to sporophytes than solutions containing a single heavy metal ion, because most sporophytes died in mixed solutions. The pH value of the culture medium dropped immediately at the beginning (the first day) of treatment, increased over the following days, and then decreased again. The pH of culture media containing multiple heavy metal ions showed greater variation than media containing a single heavy metal ion, with the extent of the decrease in pH of culture media containing multiple ions being greatest during the last period of the experiment. With increases in the concentration of heavy metals, the capacity of gametophytes to accumulate these ions increased. The blue fluorescent light emitted by the Cd- and Cd-binding protein complex existing in gametophytes in media containing different concentrations of Cd showed clearly the distribution of the ion in gametophytes and the results obtained were consistent with distribution determined using other methods.All results of the present study showed that gametophytes of L. japonica play a remarkable role as heavy metal decontaminators, especially with regard to Cd.     

Physiology and selected genes expression under cadmium stress in Arundo donax L

The effects of cadmium stress (0, 25, 50, 75, and 100 mg/L) on morpho-physiological features and selected genes (carotenoid hydroxilase, amidase, GR, bHLH, NRAMP and YSL) expression were demonstrated in Arundo donax L. The plants were assessed for Cd uptake and its effects on chlorophyll and antioxidants after 30 days of exposure. The expression of genes conferring metal tolerance was evaluated after 10 days of Cd exposure. The results showed a maximum Cd uptake in roots (872 mg/kg) followed by stem (734 mg/kg) and leaves (298 mg/kg) at highest supplied Cd concentration. The Cd uptake reduced dry weight, Chla, Chlb, and total Chl contents of giant reed. The SOD, CAT, POD activities and MDA content increased at the maximum Cd concentration over control. The highest genes expression for carotenoid hydroxylase, glutathione reductase and amidase was observed in plants exposed to 100 mg/L. However, differential bHLH gene expression and slightly increased gene expression of NRAMP was noted for different Cd treatments. Amidase expressed under Cd stress which is pioneer report in A. donax. These results provided insights into the mechanisms of A. donax tolerance and survival under Cd Stress.