Accumulation and localization of lead in Eisenia foetida (Oligochaeta) tissues.

1. Accumulation and distribution of lead in tissues of Eisenia foetida (Oligochaeta) living in soils with different concentrations PbO2 was studied histochemically and with the use of the dithizione method. 2. The earthworms absorb lead from the soil through the alimentary canal as well as through the body wall. this leads to considerable accumulation of this metal in epithelial cells, especially in the epithelial gland cells of the body wall and of the alimentary tract. 3. High concentration of lead in the soil does not favour increased accumulation of lead in the earthworms' organisms. The histochemical data show that the most intense accumulation occurs when the concentration of PbO2 is 0-4 mg/1-00 g soil.     

The effect of EDTA and EDDS on lead uptake and localization in hydroponically grown Pisum sativum L.

Pisum sativum plants were treated for 3 days with an aqueous solution of 100 μM Pb(NO₃)₂ or with a mixture of lead nitrate and ethylenediaminetetraacetic acid (EDTA) or [S,S]-ethylenediaminedisuccinic acid (EDDS) at equimolar concentrations. Lead decline from the incubation media and its accumulation and localization at the morphological and ultrastructural levels as well as plant growth parameters (root growth, root and shoot dry weight) were estimated after 1 and 3 days of treatment. The tested chelators, especially EDTA, significantly diminished Pb uptake by plants as compared to the lead nitrate-treated material. Simultaneously, EDTA significantly enhanced Pb translocation from roots to shoots. In the presence of both chelates, plant growth parameters remained considerably higher than in the case of uncomplexed Pb. Considerable differences between the tested chelators were visible in Pb localization both at the morphological and ultrastructural level. In Pb+EDTA-treated roots, lead was mainly located in the apical parts, while in Pb+EDDS-exposed material Pb was evenly distributed along the whole root length. Transmission electron microscopy and EDS analysis revealed that in meristematic cells of the roots incubated in Pb+EDTA, large electron-dense lead deposits were located in vacuoles and small granules were rarely noticed in cell walls or cytoplasm, while after Pb+EDDS treatment metal deposits were restricted to the border between plasmalemma and cell wall. Such results imply different ways of transport of those complexed Pb forms.     

Chemical and ultrastructural examination of lead-induced morphological convertants of Bacillus subtilis.

Actively-growing Bacillus subtilis 168 cells, exposed to lead nitrate, had only slightly decreased ability to bind the divalent cation magnesium. The nature and quantity of the major cell wall metal binding components, teichoic and teichuronic acids, and the carbohydrate constituents of the peptidoglycan remained relatively constant. Purified cell walls, isolated from cells exposed to lead for 6 and 13 days, retained 9.9 micrograms Pb+2 and 3.5 micrograns Pb+2/mg cell wall, respectively. The occurrence of this lead in the isolated cell wall did not interfere with its Mg2+-binding capacity. While cationic binding properties, growth rate and cell yield indicated non-interference from lead, light and electron microscopic studies clearly demonstrated morphological alterations in approx. 30--50% of the lead treated cells. These alterations included the conversion to irregular spherical forms, some of which contained thickened cell walls. These anomalies are virtually identical to those reported for mutants of this bacterium derived via the introduction of classical mutagens. Protoplasts, similar to those produced by antibiotic and enzymatic treatments, were also present in the lead-treated cells. Although the most tenable explanation appeared to be cellular mutations, the morphological convertants appear to be derived from lead's interference with cell wall biosynthesis process and/or the assemblage of cell wall subunits.     

Effects of lead and lead–melatonin exposure on protein and gene expression of metal transporters,proteins and the copper/zinc ratio in rats

Human lead (Pb) exposure induces many adverse health effects, including some related to lead accumulation in organs. Although lead bio-distribution in the body has been described, the molecular mechanism underlying distribution and excretion is not well understood. The transport of essential and toxic metals is principally mediated by proteins. How lead affects the expression of metal transporter proteins in the principal metal excretory organs, i.e., the liver and kidney, is unknown. Considering that co-administration of melatonin and lead reduces the toxic effects of lead and lead levels in the blood in vivo, we examined how lead and co-administration of lead and melatonin affect the gene and protein expression of metal transporter proteins (ZIP8, ZIP14, CTR1 and DMT1) in these organs. Rats were exposed intraperitoneally to lead or lead-melatonin. Our results show that Pb exposure induces changes in the protein and gene expression of ZIP8, ZIP14 and CTR1. Alterations in the copper/zinc ratio found in the blood, liver and kidney were likely related to these changes. With DMT1 expression (gene and protein), a positive correlation was found with lead levels in the kidney. Co-administration of melatonin and lead reduced lead-induced DMT1 expression through an unknown mechanism. This effect of melatonin relates to reduced lead levels in the blood and kidney. The metal transport protein function and our results suggest that DMT1 likely contributes to lead accumulation in organs. These data further elucidate the effects of lead on Cu and Zn and the molecular mechanism underlying lead bio-distribution in animals.     

Comparison between lead accumulation of Pomphorhynchus laevis (Palaeacanthocephala) in the intestine of chub (Leuciscus cephalus) and in the body cavity of goldfish (Carassius auratus auratus)

This experimental study assessed the role of the microhabitat in the uptake of metals by adult acanthocephalans. We examined the accumulation of lead by adult Pomphorhynchus laevis in the intestine of chub (Leuciscus cephalus) and compared it with that in goldfish, Carassius auratus auratus, in which the parasites penetrate the intestinal wall and enter the body cavity. Chub and goldfish experimentally infected with adult Pomphorhynchus laevis were exposed to 0.01 mg l(-1) Pb(2+) over 3 weeks. Lead was rapidly accumulated in the intestinal acanthocephalans reaching a mean concentration of 7.3 microg g(-1). This concentration was significantly greater than in the host muscle, liver and intestine and more than 730 times higher than the exposure concentration. Intraperitoneal P. laevis in goldfish exposed to lead did not accumulate the metal. Thus, it was conclusively shown that metal accumulation in acanthocephalans is associated with the intestinal location and does not occur in the body cavity.     

植物对铅胁迫的耐性及其解毒机制研究进展

植物对重金属元素的耐性、积累特性是利用植物修复铅污染土壤的前提,因而需要全面理解植物对铅吸收、转运、积累和解毒的一系列生理机制.本文从植物自身对铅的适应和防御机制出发,综述了细胞壁和液泡在植物细胞钝化与铅积累中的功能;根系分泌物对铅生物有效性的影响;超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）、谷光苷肽还原酶（GR）、抗坏血酸过氧化物酶（APX）和植物螯合肽、谷胱甘肽在铅解毒中的作用,以及金属硫蛋白和铅特异基因表达的研究进展.并对未来该领域的研究以及铅污染环境植物修复技术的发展进行了展望.     

Alpha spectrin is essential for morphogenesis and body wall muscle formation in Caenorhabditis elegans

A common feature of multicellular animals is the ubiquitous presence of the spectrin cytoskeleton. Although discovered over 30 yr ago, the function of spectrin in non-erythrocytes has remained elusive. We have found that the spc-1 gene encodes the only alpha spectrin gene in the Caenorhabditis elegans genome. During embryogenesis, alpha spectrin localizes to the cell membrane in most if not all cells, starting at the first cell stage. Interestingly, this localization is dependent on beta spectrin but not beta(Heavy) spectrin. Furthermore, analysis of spc-1 mutants indicates that beta spectrin requires alpha spectrin to be stably recruited to the cell membrane. Animals lacking functional alpha spectrin fail to complete embryonic elongation and die just after hatching. These mutant animals have defects in the organization of the hypodermal apical actin cytoskeleton that is required for elongation. In addition, we find that the process of elongation is required for the proper differentiation of the body wall muscle. Specifically, when compared with myofilaments in wild-type animals the myofilaments of the body wall muscle in mutant animals are abnormally oriented relative to the longitudinal axis of the embryo, and the body wall muscle cells do not undergo normal cell shape changes.     

绿色食品生产中土壤作物系统铅的积累与迁移研究

研究了Pb在土壤-作物生态系统中的积累和迁移,并结合水稻绿色食品生产,进行了无机肥、有机肥和生物菌肥及其配比试验．结果表明,土壤全Pb含量随土层的加深而逐渐递减,收获后土壤全Pb含量在0～15和15～30cm分别为11．14和9．37mg·kg^-1．水稻根从土壤中吸收Pb,并向茎、叶和籽粒中迁移．在同一生长期,水稻植株不同部位全Pb累积态势为：根>茎叶>籽粒．在不同生长期,随水稻生长发育,全Pb含量缓慢增加,至收获时,606—14和辽粳294籽粒中全Pb含量分别为0．008和0．007mg·kg^-1,均低于绿色食品标准．方差分析表明,品种间产量差异显著;不同处理间产量差异不显著．试验结果表明。可以用有机肥或生物菌肥来代替无机肥进行水稻生产．     

Chronic hypoxia induced ultrastructural changes in the rat adrenal zona glomerulosa

The adrenal cortex plays an important role in adaptation to various forms of stress, including hypoxia. While physiological changes in the aldosterone metabolism during hypoxia have been extensively described, few studies have focused on the morphological changes in the adrenal glands under chronic hypoxia. We studied the ultrastructure of the zona glomerulosa of 6-month-old Wistar rats exposed to chronic normobaric hypoxia. Animals were divided into two groups: control (n=12) and hypoxic (n=12). In this latter group, the animals were kept at 7% O2 concentration after a gradual adaptation (21, 15, 12, 10, 8, 7 vol% O2). The duration of the study was 112 days. In comparison with normoxic rats, body weight and adrenal gland weight of hypoxic animals was significantly reduced by 18.5% (p=0.006) and 14.7% (p=0.001) respectively. The thickness of the zona glomerulosa decreased due to atrophy of cells. The main ultrastructural changes observed were: 1) a decrease in, or complete elimination of, lipid droplet content; 2) a marked increase in lysosome number; and 3) the presence of giant mitochondria. Our findings show that rats fail to adapt to severe chronic hypoxia. The ultrastructural changes in the zona glomerulosa found in the present study could reflect changes in the aldosterone pathway.     

The effect of pre-incubation of Allium cepa L. roots in the ATH-rich extract on Pb uptake and localization

The positive influence of anthocyanin (ATH) on toxic metal-treated plant material is well documented; however, it is still not explained if it is caused by changes in element absorption and distribution. Therefore, detailed analysis of the effect of the ATH-rich extract from red cabbage leaves on Pb uptake and localization at morphological, anatomical and ultrastructural level was the goal of this study. Two-day-old adventitious roots of Allium cepa L. (cv. Polanowska) were treated for 2 h with the aqueous solution of Pb(NO₃)₂ at the concentration of 100 μM with or without preliminary incubation in the anthocyanin-rich extract from Brassica oleracea L. var. capitata rubra leaves (250 μM, 3 h). The red cabbage extract did not change the total Pb uptake but it enhanced the translocation of accumulated metal from roots to shoots. Within the pretreated roots, more Pb was deposited in their basal part and definitely smaller amount of the metal was bound in the apoplast of the outer layers of cortex cells. The ultrastructural analysis (transmission electron microscopy and X-ray microanalysis) revealed that the ATH-rich extract lowered the number of Pb deposits in intracellular spaces, cell wall and cytoplasm of root meristematic cells as well as in such organelles important to cell metabolism as mitochondria, plastids and nucleus. The Pb deposits were preferably localised in those vacuoles where ATH also occurred. This sequestration of Pb in vacuoles is probably responsible for reduction of metal cytotoxicity and consequently could lead to better plant growth.     

Properties of lead deposits in cell walls of radish (Raphanus sativus) roots

Various mechanisms are involved in detoxification of heavy metals such as lead (Pb) in plant cells. Most of the Pb taken up by plants accumulates in their roots. However, the detailed properties of Pb complexes in roots remain unclear. We have investigated the properties of Pb deposits in root cell walls of radish (Raphanus sativus L.) seedlings grown on glass beads bed containing Pb pellets, which are the source of Pb-contamination in shooting range soils. Pb deposits were tightly bound to cell walls. Cell wall fragments containing about 50,000 ppm Pb were prepared from the roots. After extracting Pb from the cell wall fragments using HCl, Pb ions were recombined with the Pb-extracted cell wall fragments in a solution containing Pb acetate. When the cell wall fragments were treated with pectinase (E.C. 3.2.1.15) and were chemically modified with 1-ethyl-3-dimethylamino-propylcarboimide, the Pb-rebinding ability of the treated cell wall fragments decreased. When acid-treated cell wall fragments were incubated in a solution containing Pb²⁺ and excess amounts of a chelating agent, Pb recombined with the cell wall fragments were measured to estimate the affinity between Pb²⁺ and the cell wall fragments. Our data show that Pb²⁺ binds to carboxyl groups of cell walls. The source of the carboxyl groups is suggested to be pectic compounds. A stability constant of the Pb-cell wall complex was estimated to be about 10⁸. The role of root cell walls in the mechanism underlying heavy metal tolerance was discussed.     

Motor behavior and brain enzymatic changes after acute lead intoxication on different strains of mice

Lead is a nonphysiological metal that has been implicated in toxic processes that affect several organ systems in humans and other animals. Although the brain generally has stronger protective mechanisms against toxic substances than other organs have, exposure to lead results in several neurophysiological and behavioral symptoms. The administration of a single injection (i.p.) of lead acetate in mice is a model of acute Pb2 + toxicity. In the present study, this model was used to explore the magnitude of the effect of different doses, time intervals and mice strains on several biobehavioral parameters. We investigated the effects of acute lead acetate administration on body and brain weight, brain lead acetate accumulation and specially, spontaneous locomotion and brain catalase activity. Lead acetate was injected i.p. in outbred (Swiss or CD1) and inbred (BALB/c, C57BL/J6 or DBA/2) mice at doses of 0, 50, 100, 150 or 200 mg/kg. At different time intervals following this acute treatment, several biochemical, physiological and behavioral responses were recorded. Results indicated that acute lead acetate has deleterious dose-dependent effects on brain and body weight. The effect on body weight in the present study was transient, although lead acetate was detected in neural tissues for several days after administration. Spontaneous locomotor activity only was reduced up until 24 hours. The effect of lead on body weight was strain-dependent, with Swiss mice showing greater resistance compared to the other strains. Total brain catalase activity in lead-pretreated Swiss mice showed a significant induction. This enzymatic upregulation could provide a protective mechanism for oxidative stress in these mice.     

Lead accumulation in the aquatic fern Azolla filiculoides.

In this study, we characterized lead (Pb2+) accumulation and storage by the aquatic fern Azolla filiculoides. Lead precipitates were detected in the vacuoles of mesophyll cells of Azolla plants cultured for 6 d in rich growth medium containing 20 mg l(-1) Pb2+. Energy dispersive spectroscopy (EDS) analysis of the relative element content of leaves collected from these plants revealed a 100% increase in the levels of P, S, Na and Ca and a 40% decrease in Mg and Cl compared to the untreated plants. Both Azolla whole plants and isolated apoplasts were incubated for 6 d in 20 mg l(-1) Pb2+. Lead content in the whole plant composed 0.37%, 2.3% and 1.8% of the dry weight after 2, 4 and 6 d of growth, respectively, while the isolated Azolla apoplast contained 0.125%, 1.22% and 1.4% Pb2+, respectively. Lead content in Azolla whole plant increase by 200%, 100% and 22% after 2, 4 and 6 d of growth, respectively, when compared to Azolla apoplast. Dark, electron dense deposits of lead were observed in light and transmission electron microscope in leaf cells treated with lead. All the observed lead deposits were localized in vacuoles while larger lead deposits were found in mature leaves than in young leaves. No lead deposits were found in cells of the cyanobiont Anabaena when the plants were exposed to similar conditions. Activity and content of V-H+-ATPase were studied in Azolla plants grown in the presence of 20, 40 and 80 mg l(-1) of lead for a period of 4 d. Activity of V-H+-ATPase was increased by 190%, 210% and 220%, respectively, but the content of V-H+-ATPase was reduced by all lead concentrations.     

Chemical and physical characterization of lead in three shooting range soils in Florida

Abstract

To better understand the environmental impact of lead (Pb) in shooting range soils, Pb levels in three berm soils were characterized via size distribution, total Pb concentration, water-soluble Pb, sequential extraction and X-ray diffraction (XRD). About 60% of the mid-berm soils of ranges-G and -O existed in grain sizes between 0.5 and 0.25mm (medium sand) while range-L was most abundant in the 0.25–0.106mm (fine sand) size fraction. All three range soils had the most accumulation of lead (60–70%) in the very coarse sand size (2.0–1.0 mm). In ranges-G and -L, the index shows a decreasing Pb enrichment with decreasing particle size, which may be a result of bullet fragmentation and abrasion in shooting range soils. Sequential extractions reveal that ranges-G and -L had the highest proportion of Pb bound to organic matter while range-O was dominated by the carbonate-bound fraction. However, a substantial proportion (one-third) of Pb in soil from the three shooting ranges was associated with carbonates. The XRD result revealed the dominance of carbonates in range-O soil, calcite in range-G soil and metallic lead in ranges-G and -O soil. The conversion of metallic lead to carbonates may be a mechanism for natural attenuation of lead in shooting range soils. Implications for remediation of shooting range soils are further discussed.     

Monoamine- and peptide-containing elements in the body wall and nervous trunks of nemerteans

Localization and morphological peculiarities of cateholamine-containing (CA-C), serotonin-(5HTIR), neurotensin-(NT-IR) and FMRFamide-immunoreactive (FMRFa-Ir) cells and processes in the body wall and lateral nervous trunks of nemerteans were investigated. The following nemertean species from three orders occurring in the White Sea were studied by fluorescent histochemistry and by immunohistochemistry: Lineus viridis, Lineus ruber and Cerebratulus sp. (Heteronemertini), Cephalothrix linearis (Palaeonemertini), and Amphiporus lactifloreus (Hoplonemertini). The similarity and characteristics of morphological types of monoamine-and peptide-containing elements, their distribution and possible participation in regulation of some functions in different nemertean species and in other invertebrates are discussed. We suggest that 5HT-IR and CA-C bi-and multipolar intra-and subepidermal open-type cells prevailing in the body wall perform a receptive function, while the FMRFa-Ir and NT-IR neurons of the nerve trunks and body wall are responsible for efferent innervation of musculature and connections within the nervous system.     

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.     

Immunohistochemical and ultrastructural changes in the renal cortex of cadmium-treated rats

The aim of this study was to determine the cadmium-induced immunohistochemical and morphological changes in the renal cortex of adult male rats exposed to high doses of cadmium for 30 d. Animals used as controls received a standard diet and water ad libitum. The animals used for this study received 15 ppm CdCl₂ in their drinking water for 1 mo. The mean arterial pressure (MAP), the mean blood Cd level, and the mean tissue Cd content were significantly higher when compared to controls (p < 0.01). Immunohistochemical studies demonstrated a weak labeling to type IV collagen and laminin, but a strong labeling to fibronectin in the renal cortex of the Cd-treated animals when compared to controls. The ultrastructural alterations found in Cd-treated rats were a diminution in the amount of filtration slits, increased fusion of foot processes in epithelial cells of the glomeruli, increase of lysosomal structures and pinocytic vesicles as well as large mitochondria in proximal tubule cells, and degenerated cells in distal tubules. Additionally, the glomerular basement membrane was slightly thickened. In conclusion, cadmium toxicity results in alterations in the renal extracellular matrix and tubular or glomerular cells, which could play an important role in renal dysfunction.     

铅在日本沼虾体内的分布和积累

应用组织化学、透射电镜和原子吸收光谱分析等方法,研究了Pb在日本沼虾各主要器官和组织中的分布和积累情况。结果表明,在浓度为0．625mg·L^-1Pb溶液暴露10d后的日本沼虾触角腺内,具有大量的电子密度较高的Pb颗粒．在电镜下细胞内的溶酶体中沉积有大量的Pb颗粒,这些Pb通过积聚,在细胞顶端部位逐渐增多,从而出现外排现象．中肠细胞内含有Pb颗粒,细胞质出现空泡化,核膜和线粒体内嵴部分解体．肝胰脏细胞内除分布有少量Pb颗粒外,细胞结构基本完整．在沼虾鳃细胞内未发现Pb颗粒,但在鳃丝之间发现少量Pb颗粒吸附在鳃丝的表面原子吸收光谱分析结果表明,触角腺中Pb含量最高,达637．6mg·kg^-1;触角腺在Pb的解毒方面起着重要作用。     

Effects of cadmium on formation of the ventral body wall in chick embryos and their prevention by zinc pretreatment.

BACKGROUND: Cadmium (Cd) is an established experimental teratogen whose effects can be reversed by pretreatment with zinc. Mesodermal development is a frequently reported target for Cd teratogenicity. The aim of this study was to examine the mechanisms of Cd induced body wall defects in chick embryos. METHODS: Chick embryos in shell-less culture were treated with 50 microl of cadmium acetate (8.9 x 10(-5) M Cd(2+)) at 60-hr incubation (H.-H. stages 16-17). Controls received equimolar sodium acetate. Other embryos were treated with various concentrations of zinc acetate and then with Cd or NaAc 1 hrs later. Development was evaluated 48 hrs later. Resin-embedded 1-microm sections were examined at earlier stages. RESULTS: Cd caused embryolethality (35%), ventral body wall defect with malpositioned lower limbs (40%), and weight reduction in survivors. After 4-hr treatment with Cd, breakdown of junctions between peridermal cells with rounding up and desquamation occurred. Shape changes were also seen in the basal layer of the ectoderm. At 4 hr, cell death was evident in lateral plate mesoderm, somites, and neuroepithelium; the lateral plate mesoderm began to grow dorsally, carrying the attached limb buds with it. Zn pretreatment protected against the lethal, teratogenic, and growth-retarding effects of Cd, as well as ectodermal changes and cell death. CONCLUSIONS: Cd disrupts peridermal cell adhesion and induces cell death in the mesoderm. This may result in abnormal growth of lateral plate mesoderm and in a body wall defect. Zn pretreatment prevents both the gross teratogenic effects and the cellular changes, most likely by competition with Cd.     

铅对山西省路域优势草本植物生长的影响及铅累积特征

采用温室盆栽试验,研究了不同浓度铅(0、500、1000、1500mg.kg-1)对14种山西省路域优势草本植物生长的影响及其铅吸收积累特征.结果表明:在14种草本植物中,随着铅浓度的增大,反枝苋和高丹草表现出明显的中毒症状,其他12种植物的株高和生物量与对照相比均无显著降低,表现出对铅污染具有一定的耐受性;藜和新麦草植株的地上部铅含量最低,各浓度铅处理下平均值分别为12.70和11.33mg.kg-1,地上部与根的铅含量比(S/R)最低,分别为0.12和0.10,表明二者为低积累植物,可用于铅污染土壤的植被恢复;红叶苋和绿叶苋植株地上部的铅迁移量最高,1500mg.kg-1铅处理下每百株铅迁移总量分别为53.37和45.29mg,可作为修复铅污染土壤的先锋植物.