Peer Reviewed: Reducing Children's Risk from Lead in Soil

Ryan, James A.; Scheckel, Kirk G.; Berti, William R.; Brown, Sally; Casteel, Stan W.; Chaney, Rufus L.; Hallfrisch, Judith; Doolan, Mark; Grevatt, Peter; Maddaloni, Mark; Mosby, Dave

doi:10.1021/es040337r

Cited by 179 publications

(152 citation statements)

References 35 publications

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“…Likewise, the abc2 mutant showed a significant reduction in PC 2 content. In contrast, vacuoles isolated from either the abc1-4 hmt1 quintuple or abc2 hmt1 double mutant showed undetectable levels of either PC 2 or PC 3 (Fig. 3F).…”

Section: Hmt1 and Pc Synthase Have Additive Effects On CD Tolerance-ementioning

confidence: 97%

Tonoplast-localized Abc2 Transporter Mediates Phytochelatin Accumulation in Vacuoles and Confers Cadmium Tolerance

Mendoza‐Cózatl

Zhai

Jobe

et al. 2010

Journal of Biological Chemistry

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Phytochelatins mediate tolerance to heavy metals in plants and some fungi by sequestering phytochelatin-metal complexes into vacuoles. To date, only Schizosaccharomyces pombe Hmt1 has been described as a phytochelatin transporter and attempts to identify orthologous phytochelatin transporters in plants and other organisms have failed. Furthermore, recent data indicate that the hmt1 mutant accumulates significant phytochelatin levels in vacuoles, suggesting that unidentified phytochelatin transporters exist in fungi. Here, we show that deletion of all vacuolar ABC transporters abolishes phytochelatin accumulation in S. pombe vacuoles and abrogates 35 S-PC 2 uptake into S. pombe microsomal vesicles. Systematic analysis of the entire S. pombe ABC transporter family identified Abc2 as a full-size ABC transporter (ABCC-type) that mediates phytochelatin transport into vacuoles. The S. pombe abc1 abc2 abc3 abc4 hmt1 quintuple and abc2 hmt1 double mutant show no detectable phytochelatins in vacuoles. Abc2 expression restores phytochelatin accumulation into vacuoles and suppresses the cadmium sensitivity of the abc quintuple mutant. A novel, unexpected, function of Hmt1 in GS-conjugate transport is also shown. In contrast to Hmt1, Abc2 orthologs are widely distributed among kingdoms and are proposed as the long-sought vacuolar phytochelatin transporters in plants and other organisms.Heavy metal contamination is a serious worldwide environmental problem caused by almost two centuries of intense industrial and mining activities, combined with an inappropriate disposal of residual waste (1, 2). Detrimental effects of heavy metals on human health may arise from occupational exposure, food intake and long-term exposure to metals in the environment, and have been linked to diabetes, hypertension, myocardial infarction, diminished lung function and certain types of cancer (3, 4). Non-essential heavy metals such as cadmium (Cd), lead (Pb), and mercury (Hg) interfere with the function of essential metals, including copper, zinc and manganese, by displacing them from their functional binding sites in proteins, thus interfering with biochemical and physiological functions (for reviews see Refs. 5-7). Because of the intrinsically high reactivity of heavy metals, exposure to elevated concentrations of both essential and non-essential metals impairs metabolism. Therefore, organisms have developed mechanisms to sense, transport, and mobilize essential metals, and other mechanisms to detoxify non-essential heavy metals (5-8). One of the most studied mechanisms mediating heavy metal detoxification involves phytochelatins, which are present in plants, algae, Schizosaccharomyces pombe and, surprisingly, Caenorhabditis elegans (5, 6, 9 -13).Phytochelatins (PCs) 4 are glutathione-derived peptides synthesized in the cytosol by the enzyme phytochelatin synthase (14 -16). In plants and S. pombe, cytosolic phytochelatinmetal complexes are transported into vacuoles (17)(18)(19)(20). In plants, PCs can also undergo long distance transport between ...

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Section: Hmt1 and Pc Synthase Have Additive Effects On CD Tolerance-ementioning

confidence: 97%

Tonoplast-localized Abc2 Transporter Mediates Phytochelatin Accumulation in Vacuoles and Confers Cadmium Tolerance

Mendoza‐Cózatl

Zhai

Jobe

et al. 2010

Journal of Biological Chemistry

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“…The methodofTessier et al [25]is the most widely used, which operationally separatesPb into5 fractions, i.e., exchangeable Pb, and Pb associated with carbonates, Fe/Mn oxides, organic matter, and residualfractions, showing decreasing bioavailability. For example, Pb inthe carbonate and Fe/Mn oxides bound fractionsis more bioavailable than Pbinthe residual fraction [26,27].However, correlations between Pb fractionation by sequential extraction and Pb bioaccessibilityare rarely established [23,28].…”

Section: Introductionmentioning

confidence: 99%

Lead bioaccessibility in 12 contaminated soils from China: Correlation to lead relative bioavailability and lead in different fractions

Cave

et al. 2015

Journal of Hazardous Materials

121

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HighlightsLead bioaccessibility in the gastric phase (GP) and Pb-RBA was generally lower in mining soils (0.4629%and 7.026%) than smelting (1992% and 3184%) and farming soils (1399% and 5161%), with more Pb in the residual fraction in mining soils. Lead bioaccessibilityvaried with assays, with SBRC (3.099%)producing significantly higher bioaccessible Pbthan other assays (0.4684%) in the gastric phase. However, Pb bioaccessibilityin the intestinal phase (IP) of all assays sharply decreased to 0.01-20%possibly due to Pbsorption to solid phase at higher pH. Lead bioaccessibility by UBM-GPassay was best correlated with Pb-RBA (r 2 =0.67), followed by IVG-GP (r 2 =0.55).Among different Pb fractions, strong correlation was found between Pb bioaccessibility/Pb-RBA andthe sum of exchangeable and carbonate fractions. Our study suggested thatUBM-GP assay has potential to determine Pbbioaccessibility in contaminated soils in China.

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“…Soil ingestion is an important pathway of exposure to Pb in children (Ryan et al 2004), domestic animals, deer, and waterfowl (Beyer and Fries 2003), and this pathway might also be expected to be important for songbirds. We sampled American robins, song sparrows, and Swainson's thrushes (Catharus ustulatus) after they had been on territories for at least several weeks, feeding primarily on invertebrates.…”

Section: Introductionmentioning

confidence: 99%

Lead exposure and poisoning of songbirds using the Coeur d'Alene River Basin, Idaho, USA

Hansen

Audet

Spears

et al. 2011

Integr Environ Assess Manag

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Previous studies have found widespread Pb poisoning of waterfowl in the Coeur d'Alene River Basin in northern Idaho, USA, which has been contaminated by mining and smelting activities. We studied the exposure of ground-feeding songbirds to Pb, sampling 204 American robins (Turdus migratorius), song sparrows (Melospiza melodia), and Swainson's thrushes (Catharus ustulatus) throughout the basin. These songbirds had mean blood Pb concentrations (mg/kg, dry weight) of less than 0.19 at a reference area (25 mg Pb/kg soil), 1.09 at moderately contaminated sites (170 to 1300 mg Pb/kg soil), and 2.06 at highly contaminated sites (2000 to 5000 mg Pb/kg soil). Based on guidelines for evaluating blood Pb in birds, 6% of robins from the highly contaminated sites had background concentrations, 24% were subclinically poisoned, 52% were clinically poisoned, and 18% were severely clinically poisoned with Pb. Blood Pb concentrations were lower in song sparrows than in robins and lowest in Swainson's thrushes. More than half of the robins and song sparrows from all contaminated sites and more than half of the Swainson's thrushes from highly contaminated sites showed at least 50% inhibition of the activity of the enzyme δ-aminolevulinic acid dehydratase (ALAD), commonly used as a measure of exposure to Pb. The highest hepatic Pb concentration of 61 mg/kg (dry weight) was detected in a song sparrow. Using Al as a marker for soil in songbird ingesta, we estimated average soil ingestion rates as 20% in robins, 17% in song sparrows, and 0.7% in Swainson's thrushes. Soil Pb in ingesta accounted for almost all of the songbirds' exposure to Pb. Based on these results, it is recommended that ecological risk assessments of ground-feeding songbirds at contaminated sites include soil ingestion as a pathway of exposure to Pb.

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Peer Reviewed: Reducing Children's Risk from Lead in Soil

Cited by 179 publications

References 35 publications

Tonoplast-localized Abc2 Transporter Mediates Phytochelatin Accumulation in Vacuoles and Confers Cadmium Tolerance

Tonoplast-localized Abc2 Transporter Mediates Phytochelatin Accumulation in Vacuoles and Confers Cadmium Tolerance

Lead bioaccessibility in 12 contaminated soils from China: Correlation to lead relative bioavailability and lead in different fractions

Lead exposure and poisoning of songbirds using the Coeur d'Alene River Basin, Idaho, USA

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