μM CdCl2 Research Articles

Cadmium stimulates mouse skin fibroblast apoptosis by affecting intracellular homeostasis

Context: Cadmium (Cd2+) is an important industrial and environmental pollutant and has been shown to induce apoptosis in a variety of cell types and tissues. Objective: To assess the specific effects of low-dose Cd2+ on the skin. This organ is easily exposed to Cd2+, but how it damages cells is not fully understood. Materials and methods: Mouse skin fibroblasts were treated with low doses of Cd2+ (0.4, 0.8 or 1.6 μM) for 12–48 h, and we observed cell morphological alterations, measured DNA damage and quantified cell viability changes. Results: Cd2+-treated fibroblasts exhibited morphological changes and evidence of DNA damage, as well as higher numbers of apoptotic and necrotic cells. There were increased caspase −3, −8 and −9 activities when fibroblasts were treated with 0.4, 0.8 and 1.6 μM CdCl2 for 24 h. Higher intracellular calcium (Ca2+) and reactive oxygen species (ROS) levels, and enhanced efflux of extracellular Ca2+ and potassium (K+). The mitochondrial membrane potential was lowered in treated cells, and the cell cycle arrested in the G0/G1 phase. Bax and Fas gene expression increased and Bcl-2 gene expression decreased. Discussion: The results demonstrate that Cd2+ exerts typical apoptotic effects in mouse skin fibroblasts. It strongly inhibited proliferation and induced apoptosis in a dose- and duration-dependent manner. Ca2+ homeostasis was disturbed by oxidative stress, mitochondrial dysfunction and caspase-mediated apoptosis. Conclusion: K+ efflux and Bax, Bcl-2 and Fas gene expression regulation play important roles in Cd2+-induced dysfunction by disrupting intracellular homeostasis in mouse skin fibroblasts.

Silicon-induced reversibility of cadmium toxicity in rice.

Silicon (Si) modulates tolerance to abiotic stresses, but little is known about the reversibility of stress effects by supplementing previously stressed plants with Si. This is surprising since recovery experiments might allow mechanisms of Si-mediated amelioration to be addressed. Rice was exposed to 10 µM CdCl2 for 4 d in hydroponics, followed by 0.6mM Si(OH)4 supplementation for 4 d. Si reversed the effects of Cd, as reflected in plant growth, photosynthesis, elemental composition, and some biochemical parameters. Cd-dependent deregulation of nutrient homeostasis was partially reversed by Si supply. Photosynthetic recovery within 48h following Si supply, coupled with strong stimulation of the ascorbate-glutathione system, indicates efficient activation of defense. The response was further verified by transcript analyses with emphasis on genes encoding members of the stress-associated protein (SAP) family. The transcriptional response to Cd was mostly reversed following Si supply. Reprogramming of the Cd response was obvious for Phytochelatin synthase 1, SAP1 , SAP14, and the transcription factor genes AP2/Erf020, Hsf31, and NAC6 whose transcript levels were strongly activated in roots of Cd-stressed rice, but down-regulated in the presence of Si. These findings, together with changes in biochemical parameters, highlight the significance of Si in growth recovery of Cd-stressed rice and indicate a decisive role for readjusting cell redox homeostasis.

Metal mixture (As–Cd–Pb)-induced cell transformation is modulated by OLA1

Environmental pollutants are complex mixtures in which metals are ubiquitous. Metal mixtures of arsenic, cadmium and lead are present in the occupational environment and generate health effects such as cardiovascular, renal and cancer diseases. Cell transformation induced by metal mixtures that depend on reactive oxygen species (ROS) generation, cell viability maintenance and avoidance of senescence was previously reported by our group. The aim of the present study was to explore the role of a Obg-like ATPase1 (OLA1) in the cell transformation of BALB/c 3T3 A31-1-1 clonal cells induced by a metal mixture (2 µM NaAsO2, 2 µM CdCl2 and 5 µM Pb(C2H3O2)2 3H2O) through ROS generation. The interest in OLA1 is justified because this protein has been proposed to be a negative regulator of the cellular antioxidant response. Small interfering RNA (siRNA) was used to knockdown OLA1 before the initiation stage of the transformation assay. We evaluated (ROS) and OLA1 protein expression throughout the initiation and promotion stages of transformation. OLA1 knockdown modulated metal mixture-induced cell transformation more strongly when the metal mixture was an initiator stimulus than when it was a promoter. The ability of the metal mixture to initiate cell transformation was diminished by OLA1 knockdown, an effect that depended on intracellular ROS levels. The effect of OLA1 was synergistic with N-Acetyl-l-cysteine (NAC) co-treatment. Oxidative stress-associated transcription factors Egr1 and Smad were also down-regulated by the OLA1 knockdown, contributing to the rescue of metal mixture cell transformation.

Bioaccumulation and effect of cadmium in the photosynthetic apparatus of Prosopis juliflora

In the present study Prosopis juliflora plants grown in hydroponics solution were exposed to 50,100 and 1000 μM CdCl2. The cadmium uptake, transport and toxicity on the photosynthetic activities in the plants were measured at 48 h after starting cadmium treatments. The results showed that the concentration of Cd2+ in P. juliflora tended to increase with addition of Cd2+ to hydroponics solution. However, the increase of Cd2+ in roots and leaves varied largely. In this sense, the accumulation of Cd2+ in P. juliflora roots increased significantly in proportion with the addition of this metal. In contrast a relatively low level of Cd2+ transportation index, and bioaccumulation factor were found in P. juliflora at 48 h after of treatments. On the other hand the maximum photochemical efficiency of photosystem II (Fv/Fm) and the activity of photosystem II (Fv/Fo) ratios in P. juliflora leaf treated with Cd2+ not showed significantly changes during the experiment. These results suggested that the photosynthetic apparatus of P. juliflora was not the primary target of the Cd2+ action. Further studies will be focused in understanding the participation of the root system in Prosopis plants with the rhizosphere activation and root adsorption to soil Cd2+ under natural conditions.

Induction of Glutathione, Ascorbate and Associated Enzymes by a Low Dose CdCl2 Pre-treatment Alleviate Fusarium Induced Oxidative Stress in Wheat

Induction of glutathione (GSH), ascorbate (ASC) as well as their associated enzymes have been investigated in co-stressed (50 μM CdCl2 pre-treatment followed by Fusarium infection) wheat seedlings. An enhanced GSH content, GSH/GSSG ratio and ASC content was observed in co-stressed tissues as compared to Fusarium infected tissues. Further, co-stressed tissues showed an increased activity of the antioxidant enzymes such as ascorbate peroxidase (APX) and glutathione reductase (GR) involved in glutathione-ascorbate cycle as well as glutathione peroxidase (GSHPx) and glutathione-S-transferase (GST) as glutathione associated enzymes when compared with Fusarium infected, Cd2+ pre-treated and untreated control tissues. In contrast, a decline in hydrogen peroxide (H2O2) and oxidised glutathione (GSSG) content was observed in co-stressed tissues as compared to Fusarium infected tissues. Thus, a low dose (50 μM) Cd2+ pre-treatment induced both the enzymatic and non-enzymatic antioxidants to maintain redox state at cellular level. Induction of these enzymes is suggested to be a part of defence system and play important role in offering resistance against Fusarium infection in wheat.

Physiological responses of Allium cepa var. agrogarum L. plants to Cadmium stress

This study aimed to determine the effects of different Cd concentrations (0, 1, 10, 100, and 300 μM CdCl₂) on Allium plantlets. To achieve this goal, we examined the (1) dynamics of Cd²⁺ flux in the rhizosphere, (2) partitioning of Cd between roots and leaves, (3) formation of reactive oxygen species (ROS), (4) levels of H₂O₂ and chlorophyll, and (5) translocation of several macro- and micronutrients. A strong net Cd²⁺ influx was observed in the root apex after exposure to 100 μM Cd for 24 h. Exposure to either 1 or 10 μM Cd for 96 h presented no evident influence on root growth. However, treatments with 100 to 300 μM Cd for 72 h significantly inhibited root growth. ROS levels increased in roots and leaves with increasing Cd concentrations. The concentration of photosynthetic pigments, except for carotenoids on day 4, increased with increasing Cd concentrations and treatment duration. Cd accumulation decreased photosynthetic carbon assimilation but exerted no effects on diurnal patterns. Cd accumulated in roots and leaves, but a larger content was detected on roots than on leaves. Several macro- and micronutrients showed tissue- and concentration-specific responses to Cd.

Protection to Fusarium oxysporum induced oxidative stress in wheat by a sub-lethal dose of Cd2+ pre-treatment.

A sub-lethal dose (50 μM) of cadmium chloride (CdCl2) pre-treatment protected wheat (Triticum aestivum, cv. Sonalika) seedlings against Fusarium oxysporum by antagonizing oxidative stress developed during infection. A reduced level of H2O2 content was observed in case of co-stressed (50 μM CdCl2 pre-treatment followed by Fusarium oxysporum infection) tissues as compared with healthy phenotypes. An elevated concentration of SA as well as DPPH, ABTS free radical scavenging activity was observed in co-stressed tissues as compared with Fusarium-infected seedlings. In contrast, lipid peroxidation and protein oxidation in co-stressed tissues were comparatively lower when compared with Fusarium-infected seedlings. However, total phenolic and chlorophyll contents were observed to be marginal in Fusarium-infected tissues as compared with co- stressed, untreated control and Cd2+ pre-treated seedlings. Thus, a comparative biochemical assay with relation to the oxidative stress in infected, uninfected and co-stressed tissues suggest the protective nature of a low dose (50 μM) of Cd2+ against Fusarium infection in wheat. Hence, a Cd2+ pre-treatment offered resistance to wheat directly and/or indirectly by reducing the oxidative stress developed during Fusarium infection.

Heme oxygenase-1 attenuates cadmium-induced mitochondrial-caspase 3- dependent apoptosis in human hepatoma cell line.

BackgroundCadmium (Cd) is a well known environmental and industrial toxicant causing damaging effects in numerous organs. In this study, we examined the role of heme oxygenase-1 (HO-1) in modulating the Cd-induced apoptosis in human hepatoma (HepG2) cells after 24 h exposure.MethodsHepG2 cells were exposed to 5 and 10 μM Cd as CdCl2 for 24 h while other sets of cells were pre-treated with either 10 μM Cobalt protoporphyrin (CoPPIX) or 10 μM Tin protoporphyrin (SnPPIX) for 24 h, or 50 μM Z-DEVD-FMK for 1 h before exposure to 5 and 10 μM CdCl2 for 24 h. Expressions of caspase 3, cytosolic cytochrome c, mitochondrial Bax and anti-apoptotic BCL-xl proteins were assessed by western blot. Intracellular reactive oxygen species (ROS) production was determined using the dihydrofluorescein diacetate (H2DFA) method. Cell viability was assessed by MTT assay, while a flow cytometry method was used to assess the level of apoptosis in the cell populations.ResultsOur results show that there were a significant increase in the expression of cytosolic cytochrome c, mitochondrial Bax protein, and caspase 3 at 5 and 10 μM compared to the control, but these increases were attenuated by the presence of CoPPIX. The presence of SnPPIX significantly enhanced Cd-induced caspase 3 activities. CoPPIX significantly decreased the level of ROS production by 24.6 and 22.2 % in 5 and 10 μM CdCl2, respectively, but SnPPIX caused a significant increase in ROS production in the presence of CdCl2. HepG2 cell viability was also significantly impaired by 13.89 and 32.53 % in the presence of 5 and 10 μM CdCl2, respectively, but the presence of CoPPIX and Z-DEVD-FMK significantly enhanced cell survival, while SnPPIX enhanced Cd-impaired cell viability. The presence of CoPPIX and Z-DEVD-FMK also significantly decreased the population of apoptotic and necrotic cells compared with Cd.ConclusionIn summary, the present study showed that HO-1 attenuates the Cd-induced caspase 3 dependent pathway of apoptosis in HepG2 cells, probably by modulating Cd-induced oxidative stress.

Cadmium-Induced Hydrogen Accumulation Is Involved in Cadmium Tolerance in Brassica campestris by Reestablishment of Reduced Glutathione Homeostasis.

Hydrogen gas (H2) was recently proposed as a therapeutic antioxidant and signaling molecule in clinical trials. However, the underlying physiological roles of H2 in plants remain unclear. In the present study, hydrogen-rich water (HRW) was used to characterize the physiological roles of H2 in enhancing the tolerance of Brassica campestris against cadmium (Cd). The results showed that both 50 μM CdCl2 and 50%-saturated HRW induced an increase of endogenous H2 in Brassica campestris seedlings, and HRW alleviated Cd toxicity related to growth inhibition and oxidative damage. Seedlings supplied with HRW exhibited increased root length and reduced lipid peroxidation, similar to plants receiving GSH post-treatment. Additionally, seedlings post-treated with HRW accumulated higher levels of reduced glutathione (GSH) and ascorbic acid (AsA) and showed increased GST and GPX activities in roots. Molecular evidence illustrated that the expression of genes such as GS, GR1 and GR2, which were down-regulated following the addition of Cd, GSH or BSO, could be reversed to varying degrees by the addition of HRW. Based on these results, it could be proposed that H2 might be an important regulator for enhancing the tolerance of Brassica campestris seedlings against Cd, mainly by governing reduced glutathione homeostasis.

Acquired tolerance to cadmium following long-term acclimation to CdCl2 in rice suspension cultures

Little is known concerning the long-term effects of cadmium (Cd) on plants. Here, rice (Oryza sativa L.) suspension cultures acquired tolerance to Cd toxicity after treated with 250 μM CdCl2 for 1 month, ensued with 300 μM CdCl2 for 18 months (acclimation). The tolerance was found associated with enhanced antioxidative capacity. The activities of superoxide dismutase, catalase and guaiacol peroxidase in acclimated cells were 1.58-, 3.16- and 11.24-fold respectively higher than that in non-acclimated cells when these cells were exposed to 300 μM CdCl2 for 4 days. Cd disturbed the homeostasis of ascorbate–dehydroascorbate (ASC–DHA) buffer system in the non-acclimated cells indicated by a sharp decrease in the ASC contents, whilst the ASC–DHA system was not affected in the acclimated cells. The acclimation also blocked the burst of hydrogen peroxide (H2O2) observed in the non-acclimated cells under Cd stress and conferred rice cells tolerance to H2O2 in vitro. To our knowledge, this is the first report of long-term effects of Cd on cell suspensions. This culture system may be further used to study the stress resistance breeding of crops.

English

An experiment was carried out in sand-filled pots under normal temperature (28±2oC) to assess the role of exogenously applied ascorbic acid in alleviating the effect of cadmium (Cd) stress on four barley (Hordeum vulgare L.) genotypes (Jau-83, Jau-87, Paidar 91 and Haider 93). After germination, seedlings were exposed to different Cd concentrations (0, 100, 300, 500 and 700 μM CdCl2) along with AsA (200 mg L) and grown for 15 days. The results suggested that exposure to increased Cd levels caused a significant reduction in growth and mineral nutrients contents of barley seedlings. However, there was a noticeable difference in the effect of Cd on mineral concentrations among genotypes and the difference mainly coincided with differential accumulation of Cd in the shoot and root tissues. When AsA was applied to Cd-stressed plants, it decreased Cd accumulation in shoots and roots and also showed partial reversal of Cd stress effects. It was also observed that at the same Cd concentrations Cd tolerance index of Jau-83 was the highest among the four barley genotypes, indicating that Jau-83 had lower Cd contents in roots may be more tolerant to Cd stress. The application of AsA was effective in reducing the toxicity of increased Cd by reducing the root or shoots Cd contents, as well as by improving the seedling growth attributes and the mineral nutrients in barley. © 2016 Friends Science Publishers

In vivo DNA mismatch repair measurement in zebrafish embryos and its use in screening of environmental carcinogens

Impairment of DNA mismatch repair (MMR) function leads to the development and progression of certain cancers. Many environmental contaminants can target DNA MMR system. Currently, measurement of MMR activity is limited to in vitro or in vivo methods at the cell line level, and reports on measurement of MMR activity at the live organism level are lacking. Here, we report an efficient method to measure DNA MMR activity in zebrafish embryos. A G-T mismatch was introduced into enhanced green fluorescent protein (EGFP) gene. Repair of the G-T mismatch to G-C in the heteroduplex plasmid generates a functional EGFP expression. The heteroduplex plasmid and a similarly constructed homoduplex plasmid were injected in parallel into the same batch of embryos at 1-cell stage and EGFP expression in EGFP positive embryos was quantified at 24h after injection. MMR efficiency was calculated as the total fluorescence intensity of embryos injected with the heteroduplex construct divided by that of embryos injected with the homoduplex construct. Our results showed 73% reduction of MMR activity in embryos derived from MMR-deficient mlh1 mutant fish (positive control) when compared with embryos from MMR-competent wild type AB line fish, indicating feasibility of in vivo MMR activity measurement in zebrafish embryos. We further applied this novel assay for measurement of MMR efficiency in embryos exposed to environmental chemicals such as cadmium chloride (CdCl2), benzo[a]pyrene (BaP), and perfluorooctanesulphonic acid (PFOS) from 6hpf to 24hpf. We observed significant reductions of MMR efficiency in embryos exposed to 0.1μM CdCl2 (52%) and 0.5μM BaP (34%), but no effect in embryos exposed to PFOS. Our study for the first time provides a model system for in vivo measurement of DNA MMR activity at the organism level, which has important implications in risk assessment of various environmental carcinogens.

The Effects of Cadmium at Low Environmental Concentrations on THP-1 Macrophage Apoptosis.

Cadmium at environmental concentrations is a risk factor for many diseases, including cardiovascular and neurodegenerative diseases, in which macrophages play an important role. The aim of this study was to evaluate the effects of cadmium at low environmental (nanomolar) concentrations on apoptotic processes in THP-1(acute monocytic leukemia cells line)-derived macrophages, with special focus on mitochondrial events involved. Macrophages were incubated with various cadmium chloride (CdCl2) solutions for 48 h at final concentrations of 5 nM, 20 nM, 200 nM and 2 µM CdCl2. Cell viability was measured using flow cytometry. Flow cytometric measurement (annexin V/FITC (annexin V/fluorescein isothiocyanate) and PI (propidium iodide) double staining) was used to quantify the extent of apoptosis. Fluorescence and confocal microscopy were used for imaging of apoptosis process. Changes in mitochondrial membrane potential were monitored using cytofluorimetry after cell staining with JC-1(5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazol-carbocyane iodide) probe. Mitochondrial ROS (reactive oxygen species) levels were measured cytofluorimetrically after incubation of cells with mitochondrial superoxide indicator (MitoSOX) red fluorescent marker. The mRNA expression of Bcl-2 and Bax was analysed with qRT-PCR. Our study demonstrates that cadmium, even at low environmental concentrations, exerts mitochondrial toxicity in THP-1 macrophages. Forty-eight-hour exposure to very low concentrations reduces cell viability and results in cell death by apoptosis and necrosis. The decrease in mitochondrial membrane potential, increased ROS production, increased Bax and decreased Bcl-2 mRNA expression are mitochondrial events involved in cadmium-induced apoptosis.

Cadmium chloride inhibits lactate gluconeogenesis in mouse renal proximal tubules: An in vitro metabolomic approach with (13)C NMR.

Using isolated mouse renal proximal tubules incubated with lactate as substrate, we have found that the addition of 1-50 μM cadmium chloride (CdCl2) caused a concentration-dependent decrease in lactate utilization, in glucose production and in the cellular level of ATP, coenzyme A, acetyl-coenzyme A and glutathione (reduced and oxidized forms). Combining enzymatic and (13)C NMR measurements in a cellular metabolomic approach, we have shown that, in the presence of 10 μM CdCl2, fluxes through the key-enzymes of gluconeogenesis, phosphoenolpyruvate carboxykinase and glucose-6-phosphatase were greatly depressed by cadmium. This was accompanied by a reduction in fluxes through the enzymes of the tricarboxylic acid cycle. Comparing the mouse and human renal metabolic responses to cadmium, it is interesting to observe that the mouse renal proximal tubule was much more sensitive than the human renal proximal tubule to the adverse effects of CdCl2. As far as renal gluconeogenesis is concerned, the mouse seems to be an appropriate and convenient animal model to study the mechanism of cadmium nephrotoxicity. However, the data obtained in the mouse should be extrapolated to humans with caution because the inhibition of fluxes through the enzymes of the tricarboxylic acid cycle in mouse tubules were not observed in human tubules.

Modulation of cytokines and chemokines expression by NAC in cadmium chloride treated human lung cells.

Cadmium (Cd), is one of the most hazardous metals found in the environment. Cd exposure through inhalation has been linked to various diseases in lungs. It was shown that Cd induces proinflammatory cytokines through oxidative stress mechanism. In this report, we studied the immunomodulatory effect of a well known antioxidant, N-acetylcysteine (NAC) on cadmium chloride (CdCl2 ) treated human lung A549 cells through human cytokine array 6. The lung cells were treated with 0 or 75 µM CdCl2 alone, 2.5 mM NAC alone, or co-treated with 2.5 mM NAC and 75 µM CdCl2 for 24 h. The viability of cells was measured by crystal violet dye. The array results were validated by human IL-1alpha enzyme- linked immunosorbent assay (ELISA) kit. The viability of the 75 µM CdCl2 alone treated cells was decreased to 44.5%, while the viability of the co-treated cells with 2.5 mM NAC was increased to 84.1% in comparison with untreated cells. In the cell lysate of CdCl2 alone treated cells, 19 and 8 cytokines were up and down-regulated, while in the medium 15 and 3 cytokines were up and downregulated in comparison with the untreated cells. In the co-treated cells, all these cytokines expression was modulated by the NAC treatment. The IL-1α ELISA result showed the same pattern of cytokine expression as the cytokine array. This study clearly showed the modulatory effect of NAC on cytokines and chemokines expression in CdCl2- treated cells and suggests the use of NAC as protective agent against cadmium toxicity. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1612-1619, 2016.

Kadmiyumun Biber Fidelerinde Fenilalanin Amonyum Liyaz Aktivitesi ve Lipid Peroksidasyonu Üzerine Etkisi

In this study, the effect on differrent concentrations (20, 40, 80µM ve 100 µM CdCl2 ) of cadmium (CdCl2) on the activity of phenylalanine ammonia-lyase (PAL) and lipid peroxidation amount in leaf and stem of Kahramanmaras- Hot (Capsicum annum L.) pepper seedlings were researched. Activity of phenylalanine ammonia-lyase (PAL), the first enzyme in the phenylpropanoid biosynthetic pathway, was increased at 2 and 4 days in KM-Hot plants exposed to CdCl2 stress. The highest PAL activity was detected in 20 μM CdCl2 application, on the four day after the application in the leaves of KM-Hot pepper. Moreover, it was observed that treatment of pepper with Cd led to an increased the rate of lipid peroxidation (which is indicated by increasing MDA content) in the leaf and stem tissues. The highest MDA content was detected in 80 μM CdCl2 application, on the four day after the application in the leaf tissues. These results suggest that the activation of PAL may be associated with increased production of MDA

An in ovo investigation into the hepatotoxicity of cadmium and chromium evaluated with light- and transmission electron microscopy and electron energy-loss spectroscopy

Excessive agriculture, transport and mining often lead to the contamination of valuable water resources. Communities using this water for drinking, washing, bathing and the irrigation of crops are continuously being exposed to these heavy metals. The most vulnerable is the developing fetus. Cadmium (Cd) and chrome (Cr) were identified as two of the most prevalent heavy metal water contaminants in South Africa. In this study, chicken embryos at the stage of early organogenesis were exposed to a single dosage of 0.430 μM physiological dosage (PD) and 430 μM (×1000 PD) CdCl2, as well as 0.476 μM (PD) and 746 μM (×1000 PD) K2Cr2O7. At day 14, when all organ systems were completely developed, the embryos were terminated and the effect of these metals on liver tissue and cellular morphology was determined with light- and transmission electron microscopy (TEM). The intracellular localization of these metals was determined using electron energy-loss spectroscopy (EELS). With light microscopy, the PD of both Cd and Cr had no effect on liver tissue or cellular morphology. At ×1000 PD both Cd and Cr caused sinusoid dilation and tissue necrosis. With TEM analysis, Cd exposed hepatocytes presented with irregular chromatin condensation, ruptured cellular membranes and damaged or absent organelles. In contrast Cr caused only slight mitochondrial damage. EELS revealed the bio-accumulation of Cd and Cr along the cristae of the mitochondria and chromatin of the nuclei.

Genotoxic potential and heart rate disorders in the Mediterranean mussel Mytilus galloprovincialis exposed to Superdispersant-25 and dispersed diesel oil

The effects of ex situ exposure of Mytilus galloprovincialis to Superdispersant-25 (S-25), diesel oil and dispersed diesel oil mixtures were studied by the impact on level of DNA damage in haemocytes (comet assay) and the cardiac activity patterns of mussels. Specimens were exposed for 72 h in a static system to diesel oil (100 μL/L and 1 mL/L), S-25 (5 and 50 μL/L), and dispersed diesel oil mixtures M1 (diesel oil 100 μL/L + S-25 5 μL/L) and M2 (diesel oil 1 mL/L + S-25 50 μL/L). For positive control 40 μM CdCl2 was used. The comet assay results indicated genotoxic potential of S-25 while the effects of diesel oil alone were not observed. The highest response was detected for M1 while the effects of M2 were not detected. The heart rate disorders were recorded for the diesel oil (1 mL/L), S-25 (50 μL/L) and both dispersed diesel oil mixtures.

Architectural and biochemical changes in embryonic tissues of maize under cadmium toxicity.

Heavy metals greatly alter plant morphology and architecture, however detailed mechanisms of such changes are not fully explored. Two experiments were conducted to investigate the influence of cadmium (CdCl2 · 2.5H2 O) on some germination, morphological, biochemical and histological characteristics of developing embryonic tissue of maize. In the first experiment, maize seeds were germinated in increasing levels of CdCl2 (200-2000 μm) in sand and measurements were taken of changes in germination and seedling development attributes. Based on these parameters, 1000 μM CdCl2 was chosen for detailed biochemical and histological measurements. In the second experiment, seeds were germinated in Petri dishes and supplied with 0 (control) or 1000 μM CdCl2 (Cd-treated). Radicle, plumule, coleoptile and coleorhiza were measured for biochemical and histological changes. The highest amount of Cd was in the coleorhiza and radicle. Free proline, soluble sugars, anthocyanin, soluble phenolics, ascorbic acid, H2 O2 and MDA were significantly higher in coleorhizae, followed by the coleoptile, radicle and plumule. Although the radicle and coleorhiza were relatively poor targets of Cd than the other tissues, Cd stress reduced cortical cell size and vascular tissues, and deformed xylem and phloem parenchyma in all plant parts. In conclusion, the main reason for reduced germination was the influence of Cd on architecture of the coleorhiza and coleoptile, which was the result of oxidative stress and other physiological changes taking place in these tissues.

Toxic effects of cadmium on flatworm stem cell dynamics: A transcriptomic and ultrastructural elucidation of underlying mechanisms.

Stem cells or undifferentiated cells can cope more easily with external stresses. To evaluate the impact of toxic compounds on stem cell dynamics in vivo, in relation to other biological responses, we use the carcinogenic element cadmium and the regenerating model organism Macrostomum lignano. Through both BrdU and anti-histone H3 immunostainings, cadmium-induced effects were investigated at different stages of the stem cell cycle. A 24-h exposure to 100 and 250 μM CdCl2 significantly decreased the number of stem cells (neoblasts) in mitosis, whereas the number of cells in the S phase remained unchanged. After this short-term exposure, the ultrastructure of the neoblasts was minimally affected in contrast to the epidermal tissues. These results were supported by gene expression data: transcripts of cdc2 and pig3 were significantly upregulated during all treatments. Both genes are involved in the cell cycle progression and are transcribed in the gonadal region, where stem cells are highly represented. Based on a substantial increase in gene expression of heat shock proteins (HSP) and their high activity in the gonadal region, we hypothesize that these proteins are key players in the protection of stem cells against external stresses. Apart from the strong HSP induction, other protective processes including cell division, apoptosis and anti-oxidative defence, were also activated. We, therefore, conclude that the protection of stem cells against external stressors may be based on the interplay between stem cell maintenance, i.e. repair and recovery through division, on one hand and apoptosis on the other hand. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1217-1228, 2016.