Pb-treated Cells Research Articles

Oxidative stress marker changes and cognitive decline prevention in Pb contaminated mice by Crocus sativus L. Supplementation and interval training

Heavy metals are contaminants hazardously affecting the animals’ and humans’ health since they are extensively utilized in the industry where proper physical activity and consuming antioxidant ingredients can be an appropriate solution for decreasing the resultant damages. This work deals with assessing the effects of Crocus sativus L. (saffron) petal extract (SPE) along with eight weeks of interval training on the cytotoxicity of lead (Pb) investigated in exposed adult male mice. SPE reduced the toxic effects of Pb that were indicated by the MTT assay. The morphological alterations of Pb-treated cells were found by fluorescent and normal microscopes when it was co-incubated with SPE. Accordingly, the 50% inhibitory concentration and the 50% lethal dose were calculated. The adult male mice were randomly placed into seven groups (six mice/group) of positive and negative controls, interval training group (Exr), Exr & Pb, SPE, SPE & Pb, and Exr & SPE & Pb treated groups. From the results, SPE did not affect catalase (CAT) activity, but it induced a significant increment of antioxidant enzyme SOD and the levels of malondialdehyde (MDA) is reduced remarkably in the brain. In the last part of the research, mice were exposed to the behavioral tasks examined by step-through ORT, MWM, and YM tests. Having interval training and SPE consumption could reverse the most defective behavioral indicators that may be protecting potential agents inspiringly to the Pb toxicity in the areas with higher heavy metals pollution.

Alleviated lead toxicity in rice plant by co-augmented action of genome doubling and TiO2 nanoparticles on gene expression, cytological and physiological changes

Lead is a very toxic and futile heavy metal for rice plants because of its injurious effects on plant growth and metabolic processes. Polyploidy or whole genome doubling increases the ability of plants to withstand biotic and abiotic stress. Considering the beneficial effects of nanoparticles and tetraploid rice, this research was conducted to examine the effectiveness of tetraploid and titanium dioxide nanoparticles (TiO2 NPs) in mitigating the toxic effects of lead. A diploid (E22-2x) and it's tetraploid (T-42) rice line were treated with Pb (200 μM) and TiO2 NPs (15 mg L−1). Lead toxicity dramatically reduced shoot length (16 % and 4 %) and root length (17 % and 9 %), biological yield (55 % and 36 %), and photosynthetic activity, as evidenced by lower levels of chlorophyll a and b (30 % and 9 %) in E-22 and T-42 rice cultivars compared to the control rice plants, respectively. Furthermore, lead toxicity amplified the levels of reactive oxygen species (ROS), such as malondialdehyde and H2O2, while decreasing activities of all antioxidant enzymes, such as superoxidase, peroxidase, and glutathione predominately in the diploid cultivar. Transmission electron microscopy and semi-thin section observations revealed that Pb-treated cells in E22-2x had more cell abnormalities than T-42, such as irregularly shaped mitochondria, cell wall, and reduced root cell size. Polyploidy and TiO2 reduced Pb uptake in rice cultivars and expression levels of metal transporter genes such as OsHMA9 and OsNRAMP5. According to the findings, genome doubling alleviates Pb toxicity by reducing Pb accumulation, ROS, and cell damage. Tetraploid rice can withstand the toxic effect of Pb better than diploid rice, and TiO2 NPs can alleviate the toxic impact of Pb. Our study findings act as a roadmap for future research endeavours, directing the focus toward risk management and assessing long-term impacts to balance environmental sustainability and agricultural growth.

From cells highly tolerant to Zn and Pb to fully fertile plants – Selection of tolerant lines with in vitro culture

Viola arvensis cells were selected after treatment with Zn or Pb and regenerated into plants likely to have higher tolerance levels than the initial plant. The surviving cells in the suspension treated with 2000 μM of Zn, 2000 μM of Pb or 0 μM for 72 h were maintained on a solidified half-strength MS medium supplemented with 0.5 mg L−1 TDZ to induce divisions and organogenesis. The adventitious shoots obtained were rooted on a half-strength MS medium with 1 mg L−1 IBA. Regenerants derived from the Zn- and Pb-treated cells were vigorous and fully fertile. The in vitro conditions and metal impact generated a low genome alteration and overall low genetic diversity of regenerants compared to the initial plant and plants from the natural population. The cells of regenerants obtained after Pb treatment represented an approximately 12% higher tolerance level to Pb than the cells of the initial plant. This is the first report of plant regeneration from highly tolerant cells selected by heavy metal treatment. Regenerants successfully obtained in vitro could be considered as a source material for the recultivation of areas polluted with heavy metals.

Lead induces apoptosis in mouse TM3 Leydig cells through the Fas/FasL death receptor pathway

The study was aimed to investigate the effect of Pb toxicity on mouse Leydig cells and its molecular mechanism. The TM3 cells were cultured in vitro and exposed to Pb at different concentrations for 24h. The effects of Pb on cell proliferation and apoptosis were analyzed with MTT and Annexin V-FITC/PI via flow cytometry, respectively. Expression levels of Fas, Fas-L and caspase-8 in TM3 cells were determined by western blot. As well as the inhibitory effect of the caspase-8 inhibitor Z-IETD-FMK on cell apoptosis. We found that Pb treatment significantly decreased the cellar viability (P<0.05), increased the apoptosis (P<0.01) and the Fas, FasL, and caspase-8 expression levels in Pb-treated cells as compared to the control cells (P<0.05 or P<0.01). Furthermore, the caspase-8 inhibitor effectively block the Pb-induced cell apoptosis. Taken together, our data suggest that Pb-induced TM3 cell toxic effect may involve in the Fas/FasL death receptor signaling pathway.

Evaluation of the Role of Glutathione in the Lead-Induced Toxicity in Saccharomyces cerevisiae

The effect of intracellular reduced glutathione (GSH) in the lead stress response of Saccharomyces cerevisiae was investigated. Yeast cells exposed to Pb, for 3h, lost the cell proliferation capacity (viability) and decreased intracellular GSH level. The Pb-induced loss of cell viability was compared among yeast cells deficient in GSH1 (∆gsh1) or GSH2 (∆gsh2) genes and wild-type (WT) cells. When exposed to Pb, ∆gsh1 and ∆gsh2 cells did not display an increased loss of viability, compared with WT cells. However, the depletion of cellular thiols, including GSH, by treatment of WT cells with iodoacetamide (an alkylating agent, which binds covalently to thiol group), increased the loss of viability in Pb-treated cells. In contrast, GSH enrichment, due to the incubation of WT cells with amino acids mixture constituting GSH (L-glutamic acid, L-cysteine and glycine), reduced the Pb-induced loss of proliferation capacity. The obtained results suggest that intracellular GSH is involved in the defence against the Pb-induced toxicity; however, at physiological concentration, GSH seems not to be sufficient to prevent the Pb-induced loss of cell viability.

APE1/Ref-1 prevents oxidative inactivation of ERK for G1-to-S progression following lead acetate exposure

Apurinic/apyrimidinic endonuclease 1 (APE1)/redox effector factor-1 is a multifunctional enzyme involved in DNA base excision repair and protein redox regulation. Previously, we have showed that lead acetate (Pb) elicits EGFR activation to initiate the SFK/PKCα/Ras/Raf-1/MKK1/2/ERK signaling cascade functioning against genotoxicity. Here, we explore whether APE1 and reactive oxygen species (ROS) affect ERK signaling and cell cycle progression following Pb exposure. We found that Pb induced APE1 expression and ROS generation in CL3 human lung cancer cells. The Pb-elicited ROS levels and cytotoxicity were further enhanced by introducing small interfering RNA specific for APE1 (siAPE1). E3330, an inhibitor of APE1 redox activity, also augmented the ROS levels and cytotoxicity in Pb-treated cells. Intriguingly, the capability of Pb to activate ERK was abolished under siAPE1 or E3330 co-treatments; conversely, forced expression of APE1 up-regulated the ERK activation by Pb or serum in both Cys65-redox activity dependent and independent manners. Moreover, APE1 formed complex with ERK2, and its redox activity could rescue ERK oxidative inactivation. APE1 redox activity also facilitated the Cyclin D1 expression and G1-to-S progression following Pb exposure. In summary, the results indicate that APE1 is a direct redox regulator of ERK for maintaining the kinase activity to promote cell proliferation.

Abstract C66: Impacts of ERK signaling on the regulation of antioxidant enzymes and ROS levels in human lung cancer cells exposed to lead acetate

Abstract Lead compounds (Pb) are widespread environmental contaminants that have been evaluated as group 2A carcinogens. Recently, we showed that EGFR activation is an immediate response to Pb as a primary upstream molecule to initiate SFK and PKCα activation, and subsequently links to the Ras→Raf-1→MKK1/2→EKK signaling cascade. Also, activation of this signaling plays a defensive role against Pb genotoxicity. Here, we explore whether Pb disturbs the intracellular levels of antioxidant enzymes and reactive oxygen species (ROS), and whether ERK signaling modulates the oxidative stress elicited by Pb in CL3 human non-small-cell lung adenocarcinoma cells. We found that Pb lowered the protein levels of glutathione peroxidase-1 (GPX1) and catalase, yet it induced superoxide dismutase 2 (SOD2). The phenomena were reverted upon ERK inactivation or depletion. By contrast, forced expression of the MKK1/2→ERK signaling decreased GPX1 and catalase, but enhanced SOD2 protein levels. The activities of GPX1 and catalase, but not SOD2, were declined in Pb-treated cells, and blockage of ERK activation partially rescued the decreased GPX1 activity. On the other hand, Pb elevated intracellular ROS, and ERK inactivation further enhanced its levels. The antioxidant N-acetyl-cysteine markedly prevented the cytotoxicity of Pb during ERK inactivation. These results suggest that ERK activation could mediate in scavenging ROS toxicants following Pb; yet, this signaling also participates in down-regulation of GPX1 and catalase as well as up-regulation of SOD2 at the protein levels, which probably enhances the intracellular H2O2. Thus, ERK exhibits dual and opposing roles in modulating oxidative stress caused by Pb. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr C66.

Lead induces oxidative stress and phenotypic markers of apoptosis in Saccharomyces cerevisiae

In the present work, the mode of cell death induced by Pb in Saccharomyces cerevisiae was studied. Yeast cells Pb-exposed, up to 6 h, loss progressively the capacity to proliferate and maintained the membrane integrity evaluated by the fluorescent probes bis(1,3-dibutylbarbituric acid trimethine oxonol) and propidium iodide. Pb-induced death is an active process, requiring the participation of cellular metabolism, since the simultaneous addition of cycloheximide attenuated the loss of cell proliferation capacity. Cells exposed to Pb accumulated intracellularly reactive oxygen species (ROS), evaluated by 2',7'-dichlorodihydrofluorescein diacetate. The addition of ascorbic acid (a ROS scavenger) strongly reduced the oxidative stress and impaired the loss of proliferation capacity in Pb-treated cells. Pb-exposed cells displayed nuclear morphological alterations, like chromatin fragmentation, as revealed by diaminophenylindole staining. Together, the data obtained indicate that yeast cells exposition to 1 mmol/l Pb results in severe oxidative stress which can be the trigger of programmed cell death by apoptosis.

Time-Lapse Analysis of Cell Death in Mammalian and Fungal Cells

Time-lapse video microscopy was designed to follow the movement of single cells for an unlimited period of time under physiological conditions. The system is based on two inverted microscopes located in a CO(2) incubator and equipped with charge-coupled device cameras connected to the computer. Frames were recorded every minute and the subsequent video sequence was converted to database form. The system was applied to describe the movements of normal HaCaT cells and Pb-treated cells causing the so-called apoptotic dance during cell death. The apoptotic movement was also followed in high-osmolarity glycerol-type mitogen-activated protein kinase (MAPK) null mutant of Fusarium proliferatum, a filamentous fungus, during osmotic stress. The shortest (20 min) and most vigorous death movements were observed in apoptotic fungal cells subjected to salt stress. The necrotic process at higher Pb concentration (50 microM) took 2-3 h, whereas the apoptotic process at lower Pb concentrations lasted from minutes to days.

Genetic determinants of UGT1A1 inducibility

Background UGT1A1 is induced by phenobarbital (PB). This study investigates whether the TATA box indel and two SNPs in the PBREM region are associated with the variability in the inductive phenotype. Methods Human hepatocytes (n=36) were incubated with 2 mM PB (48 h) followed by 5 μM SN-38 (1 h), a UGT1A1 probe. SN-38 glucuronide (SN-38G) in the cell media was measured by HPLC. Three UGT1A1 variants (−53(TA)6>7, −3156G>A and −3279T>G) were genotyped. Samples were considered to be induced if the SN-38G levels in PB-treated cells increased by at least 25% when compared to untreated cells, and P<0.05 (unpaired t-test). Results Significant UGT1A1 induction was observed in 81% of the cultures (fold-induction=1.7±0.4, mean±SD). The SN-38G concentrations in the basal and induced states were highly correlated (r=0.94, P 0.05). The basal and induced activities were correlated with −53(TA)6>7 (and with −3156G>A due to almost complete linkage with the −53 indel) (P G SNP (P>0.05). The fold-induction was not associated with any variants (P>0.05). Conclusions The indel at −53 affects the basal phenotype and seems to limit the hepatocyte capability of maximal induction after PB. However, variants at −53, −3156 and −3279 are not associated with variability in UGT1A1 inducibility. Clinical Pharmacology & Therapeutics (2005) 77, P25–P25; doi: 10.1016/j.clpt.2004.11.096

Reactive Oxygen Species Mediate Pyridostigmine-Induced Neuronal Apoptosis: Involvement of Muscarinic and NMDA Receptors

Pyridostigmine bromide (PB) is a reversible cholinesterase inhibitor used for treatment of myasthenia gravis and for prophylactic protection against organophosphate nerve agent. We previously showed PB can induce apoptotic death in rat brain following systemic treatment. To study mechanisms by which PB induces brain cell death, cultured rat cerebellar granule cells were used. Cytotoxicity was determined after exposure to PB (10–1000 μM) for 24 h; a high concentration of PB (>500 μM) significantly increased lactate dehydrogenase release, which was reduced by pretreatment with the antioxidant, N-t-butyl-α-phenyl-nitrone (PBN). Apoptosis, as determined by TUNEL staining, was concentration dependent (10–250 μM) after a 24-h exposure and cytotoxicity was confirmed by gel electrophoresis of DNA, release of cytochrome c from mitochondria, elevation of caspase activity, and electron microscopy. The oxidant-sensitive fluorescent dye 2′,7′-dichlorofluorescin diacetate was used to detect reactive oxidative species (ROS) generation. Pretreatment with PBN, superoxide dismutase, catalase, or the nitric oxide synthase inhibitor NG-nitro-l-arginine methyl ester (l-NAME) blocked PB-induced ROS generation and apoptotic cell death. Pretreatment with atropine or MK-801 blocked ROS generation and the subsequent neurotoxicity, showing that both muscarinic and NMDA receptors mediate the response. DNA extracted from PB-treated cells revealed oligonucleosomal fragmentation on gel electrophoresis and antioxidants attenuated the DNA fragmentation, providing further evidence for a link of ROS generation and apoptosis. These results indicate that muscarinic receptor-mediated ROS generation is an initiating factor in PB-induced apoptotic cell death and activation of the NMDA glutamate receptor is directly linked to the response.

Regulation of phenobarbital induction of the cytochrome P450 2b9/10 genes in primary mouse hepatocyte culture. Involvement of calcium- and cAMP-dependent pathways.

Phenobarbital (PB) has long been known as an inducer of drug-metabolizing enzymes in liver, but the molecular mechanism underlying this induction is still poorly understood. Using primary mouse hepatocyte culture, we have investigated the possible involvement of different regulatory pathways in PB action, by exposing PB-treated cells to various protein kinase/phosphatase modulators. Our results showed a negative role of the cAMP-dependent pathway, as treatment with cAMP-dependent protein kinase (PKA) activators (10 microM dibutyryl-cAMP and 50 microM forskolin) dramatically inhibited PB-induced Cyp2b9/10 mRNA accumulation, whereas PKA inhibitor potentiated the PB responsiveness of this gene. The cGMP-dependent protein kinase (PKG) seems to play a positive role as PKG inhibitor reduced the PB-induced level of Cyp2b9/10 mRNA. We also obtained two lines of evidence for the involvement of Ca2+ in modulating PB action. Firstly, measurements of intracellular Fura-2 fluorescence ratio in murine hepatocytes showed that long-term PB incubation (24 and 48 h) led to a significant increase of [Ca2+]i. Secondly, treatment with an intracellular Ca2+ chelator (BAPTA-AM) nearly completely abolished PB-induced Cyp2b9/10 expression. Ca2+ thus appeared to mediate PB action likely via Ca2+/calmodulin-dependent protein kinase II, as KN62, a specific inhibitor of this enzyme, also dramatically inhibited PB induction of the Cyp2b9/10 genes.

Inhibitory effect of 1-O (2 methoxy) hexadecyl glycerol and phenylbutyrate on the malignant properties of human prostate cancer cells.

The ability of the naturally occurring ether lipid, 1-O (2 methoxy) hexadecyl glycerol (MHG), and phenylbutyrate (BP) to inhibit cellular proliferation, anchorage-independent growth and cellular invasion in the human prostate cancer LnCap and DU145 cells was determined. Both MHG and PB inhibited the malignant properties of these prostate cancer cells. The concentrations required to achieve similar inhibitory effect, however, were significantly different for these two agents. MHG inhibited cell growth with equal potency in these cell lines with an IC-50 value of 93 microM for LnCap, and 97 microM for DU145. The IC-50 values for PB were 1.3 mM and 7.3 mM, respectively, for LnCap and DU145 cells. Both MHG and PB (IC-50 concentrations) inhibited the anchorage-independent growth and cellular invasion in these cells. Over 50% inhibition of anchorage-independent growth was achieved for both LnCap and DU145 cells by PB, while a lesser degree of inhibition was achieved with MHG. Both MHG- and PB-treated cells showed a reduced propensity to invade matrigels. Invasion of PB-treated LnCap and DU145 cells was reduced, respectively, by approximate 41 and 30% when compared to untreated control cells, while invasion of MHG-treated LnCap and DU145 cells was reduced to a lesser extent. Because differentiation-inducing agents may possess chemopreventive properties, the use of naturally occurring MHG and nontoxic PB in the chemoprevention of malignant diseases warrants further investigation.

Effect of acute lead treatment on coproporphyrinogen oxidase activity in HepG2 cells

Acute toxic effects of lead were evaluated on porphyrin synthesis and coproporphyrinogen oxidase (CO) activity in an in vitro model, using HepG2 cells, a hepatoma cell line of human origin. Lead concentrations for exposure treatments were 0.5, 1.0, 2.5, 5.0 μM. No significant changes were found in treated cells with respect to uroporphyrin cellular or media concentrations. Cellular protoporphyrin increased in dose–response shape, but no changes in extracellular content were found. Extracellular coproporphyrin concentration increased in a dose–response manner without changes in cellular content. The CO activity was depressed in dose–response shape, reaching 62% of control activity at 5.0 μM of lead treatment. The CO activity in Pb-treated cells was recovered after dithiothreitol (DTT) treatment, suggesting that sulphydryl groups play an essential role in the enzyme activity. The dose–response increase of coproporphyrin secretion accompanied by the depression of CO activity supports the suggestion that lead causes CO inhibition, as observed in this cellular model.

Reduction of glutamine synthetase activity in astroglia exposed in culture to low levels of inorganic lead

Astroglia serve as a site of lead (Pb) deposition in Pb-exposed animals. Thus, the potential exists for astroglial function to be impaired by elevated intracellular Pb levels. We previously showed that the specific activity of glutamine synthetase (GS), an astroglial enzyme with a key role in glutamate and ammonia metabolism in the brain, is reduced in fetal guinea pigs exposed to low levels of lead. This observation indicates either a direct effect of Pb on astroglia or an indirect systemic effect. The purpose of the present study was to test the hypothesis that Pb directly reduces GS activity in astroglia. Cultured rat astroglia were fed three times per week with medium containing 0, 0.25, 0.5, or 1 μM Pb acetate for 7, 14, or 21 days. Trypan blue dye exclusion, cell number, and GS activity were measured. Lead treatment reduced the ability of cells to exclude trypan blue in a dose- and time-dependent manner, with the greatest reduction (28%) on day 21 in the group treated with 1 μM Pb. Cell numbers were reduced a maximum of 15% on day 15, but were unaffected on days 7 and 21. The effects of Pb exposure on GS activity were much more pronounced. For example, cultures exposed to 0.25 of 1 μM Pb for 7 days showed, respectively, 17 and 52% reduction in activity from the control value. Slightly greater reductions were measured on days 14 and 21. The much greater sensitivity in vitro of GS activity than dye exclusion or cell numbers to low level lead supports a specific enzymatic inhibition. In order to test the possibility that Pb might directly inhibit GS activity Pb-treated cells, we also measured the effect of Pb on GS activity in cytosolic extracts of the cells. Pb inhibited GS activity in a dose-dependent manner ranging from 27% inhibition at 0.1 nM to 67% at 0.1 μM and 100% at 10 μM Pb. These results indicate that astroglial function is vulnerable to Pb exposure, even at low lead levels.

Effects of lead on viability and intracellular metal content of C6 rat glioma cells.

Cultured C6 rat glioma cells were exposed to lead (Pb) acetate (0, 1, 10, or 100 microM) for 3-4 d. Cells were analyzed for changes in viability and intracellular lead, iron, and copper concentrations after Pb treatment was discontinued. The results were compared with previous findings on astroglia and oligodendroglia in culture in order to evaluate C6 cultures as a model for Pb toxicity in glia. Viability was measured by three methods on the day Pb was removed from the cells (designated d 0), and 2 and 9 d after Pb treatment was discontinued (designated d 2 and 9). The methods used were trypan blue dye exclusion, total cell counts, and incorporation of [3H]-L-leucine into proteins. Small, dose-dependent reductions were observed on d 2 in the percentages of cells excluding dye. Decreased cell numbers were seen at all three Pb doses only on d 0. With respect to these two viability measurements, C6 cells responded like astroglia in culture to Pb, but not like oligodendroglia, which are more Pb-sensitive. We expected decreased amino acid incorporation to accompany the decreased viability of the cultures. Instead, increased amino acid incorporation, which indicates increased protein synthesis, was seen on d 0 and 2 at all three Pb doses, though total cellular protein did not increase. A similar response has been reported previously in oligodendroglial cultures. C6 cells treated for 3 with 1 or 100 microM Pb acetate were analyzed for intracellular metal content by atomic absorption aspectroscopy on d 4 and 11 after exposure to Pb was discontinued. The cells were found to take up large amounts of Pb intracellularly and store it for at least 11 d. Cells treated with FeCl2 instead of Pb took up Fe, but required a higher extracellular Fe concentration to achieve an intracellular Fe level comparable to that of Pb in Pb-treated cells. Pb uptake did not affect intracellular Fe or Cu concentrations. With respect to Pb and Fe uptake, C6 cells closely resembled immature astroglia in culture. Unlike C6 cells, however, astroglia showed elevations of intracellular Fe and Cu after Pb treatment. Thus, Pb effects on C6 cells resembled those on cultured oligodendroglia and astroglia in some respects but not in others. C6 cells appear to be an adequate model for selected events in glial toxicosis, such as Pb-stimulated protein synthesis in oligodendroglia and Pb uptake in astroglia, but not Pb-induced alterations of intracellular Cu and Fe in astroglia. Their use as a model for glial progenitor cells in Pb toxicity studies remains to be determined.

Uptake of heavy metals by Plectonema boryanum (cyanophyceae) into cellular components, especially polyphosphate bodies: An X-ray energy dispersive study

In situ X-ray energty dispersive analysis has been used to study heavy metal uptake in Plectonema boryanum. Air-dried cells observed in the STEM mode of the SEM show numerous polyphosphate bodies in the cells. By using this system as a probe to analyse cell sectors it was determined that the heavy metals Cd, Co, Cu, Hg, Ni, Pb and Zn are all taken up and sequestered in the cell sectors with polyphosphate bodies. Smaller amounts of the metals Cd, Cu, Hg, Pb and Zn are also concentrated in the cell sectors without polyphosphate bodies. Control polyphosphate bodies cell sectors generate high P and K signals and a low Mg signal. Sometimes a Ca peak is also generated. In Cd-exposed cells the K and Mg signal is lost from the polyphosphate body cell sectors. In Cu-treated cells the Mg and K peaks are lost from the polyphosphate body cell sectors. In Pb-treated cells the K signal is reduced from both the bodies and the cell sectors without bodies. In Hg-treated cells the K signal is lost and the Ca signal is enhanced. The other metals did not significantly affect the elemental peaks generated in the polyphosphate body cell sectors or the cell sectors without polyphosphate bodies. The sequestering of heavy metals in the polyphosphate bodies is suggested as serving a dual purpose in cells by providing a storage site for essential metals and acting as a detoxification mechanism.