Cadmium-containing granules in kidney tissue of the Atlantic white-sided dolphin (Lagenorhyncusacutus) off the Faroe Islands

Top predators from the northern sub-polar and polar areas exhibit high cadmium concentrations in their tissues. In the aim to reveal possible adverse effects, samples of five Atlantic white-sided dolphins Lagenorhyncusacutus have been collected on the occasion of the drive fishery in the Faroe Islands, for ultrastructural investigations and energy dispersive X-ray microanalyses. Cadmium concentrations were less than the limit of detection in both immature individuals and ranged from 22.7 to 31.1 μg g^?1 wet weight in the mature individuals. Two individuals with the highest cadmium concentrations exhibited electron dense mineral concretions in the basal membranes of the proximal tubules. They are spherocrystals made up of numerous strata mineral deposit of calcium and phosphorus together with cadmium. Cadmium has been detected with a molar ratio of Ca:Cd of 10:1 in the middle of these concretions. To our knowledge, this is the first report of such granules in a wild vertebrate. The role of these granules in the detoxification of the metal and the possible pathological effects are considered.     

Influence of cadmium on the distribution of the essential trace elements zinc and copper in the liver and kidneys of rats

Cd induced changes of Zn and Cd distribution in the liver and kidneys were studied in relation to Cd metallothionein (MT) synthesis. Wistar male rats were given CdCl₂ by sc injection of .8, 1.5, and 3.0 mg Cd/kg three times a week for three weeks. Cd levels of liver and kidneys increased with the increment of Cd dosage and 80–90% of Cd was found in the cytosol. The MT fractions contained 80–89% cytosolic Cd in the liver and 55–75% Cd in the kidneys. Zn concentrations in the liver increased following Cd administration, But Zn in the kidneys showed only slight increase. There was a distinct decrease of Cu concentration in the liver of the 3.0 mg group. In contrast, Cu concentrations in the kidneys increased about three times in the .8 and 1.5 mg Cd groups, but Cu in the 3.0 mg group showed only 1.5 times increase. The changes of these metal concentrations were observed mainly in the cytosol. Non-MT-Cd in the kidneys was maximum in the 1.5 mg group, but the 3.0 mg group showed significant decrease. In parallel with this decrease of Cd, Cu and Zn in the kidneys showed similar decrease. When the kidneys are injured, Zn and Cu appear to leak from this organ.     

Cadmium and zinc influx characteristics by intact corn (Zea mays L.) seedlings

Summary Cadmium and zinc uptake parameters were determined for intact corn (Zea mays L.) seedlings grown for 15 and 22 in nutrient solutions containing levels of Cd and Zn that were similar to those found in soil solutions. Uptake of both elements was assumed to follow Michaelis-Menten kinetics. Calculations were based on the concentrations of free ionic Cd (Cd²⁺) and Zn (Zn²⁺) rather than the total solution concentration. Rates of Zn uptake were measured by determining depletion of Zn for periods of up to 30 h from solutions containing initial concentrations of 1.5 and 10μmol Zn 1⁻¹. Depletion curves suggested that Zn uptake characteristics were similar at both levels of Zn in solution. The Imax for Zn uptake decreased from 550 to 400 pmol m⁻² root surface s⁻¹ between 16 and 22 d of growth while Km decreased from 2.2 to 1.5 μmol Zn²⁺ 1⁻¹. Cadmium uptake parameters were measured by controlling Cd²⁺ activities in nutrient solution betwen 6.3 to 164 nmol l⁻¹ by continuous circulation of nutrient solution through a mixed-resin system. Imax for Cd uptake was 400 pmol m⁻² root surface s⁻¹ at 15 and 22 d of growth. The magnitude of Km increased from 30 to 100 nmol Cd²⁺ 1⁻¹ during this time period. The Km value suggests that corn is efficient for Cd uptake. The results of these uptake studies are consistent with the observed uptake of Zn and Cd by corn seedlings in soils.     

Immunological properties of low molecular-weight proteins binding heavy metals in rat kidney and liver

Two homogenous fractions of hepatic metallothioneins ((Cd,Zn) MT-1 and (Cd,Zn) MT-2) and renal metal binding proteins ((Bi,Cu) BP-1 and (Bi,Cu) BP-2) were isolated from rats exposed to heavy metals and specific antisera to them were produced in rabbits.These antisera were tested by immunodiffusion and immunoelectrophoresis for their ability to bind different fractions of hepatic Cd,Zn -metallothionein and renal (Bi,Cu)-, (Hg,Cu)- and (Cd,Cu)-binding proteins. It was found that anti (Bi,Cu) BP antisera did not cross-react with hepatic (Cd,Zn) MT-1 and (Cd,Zn) MT-2. Strong immunological cross-reactions were detected between anti (Bi,Cu) BP antisera and individual forms of (Cd,Cu)-, (Hg,Cu)- and (Bi,Cu)-binding proteins isolated from rat kidneys.     

Intracellular binding of lead in the kidney: The partial isolation and characterization of postmitochondrial lead binding components

Gel chromatography of kidney postmitochondrial fractions from control rats 2 hr after injection of ²⁰³Pb or after in vitro incubation with ²⁰³Pb disclosed the presence of two fractionated Pb-binding components plus binding in the void volume and total volume regions. The binding of Pb to the two components, with molecular weights of 11,500 and 63,000 daltons, was markedly decreased in Pb-pretreated rats. Sodium dodecyl sulfate-gel electrophoresis and autoradiography showed the presence of one major ²⁰³Pb band with an estimated molecular weight of 60,000 daltons. The 11,500-dalton peak did not incorporate ¹⁴C-leucine nor did concomitant administration of cycloheximide with the ²⁰³Pb inhibit incorporation of ²⁰³Pb activity, suggesting that the component is a preformed constituent of the kidney. In vitro incubation of brain, liver and lung postmitochondrial supernatants with ²⁰³Pb disclosed that these two binding components were also present in brain but not in liver or lung, suggesting a target tissue-specific localization for these Pb-binding macromolecules.     

Effect of soil Cd addition on germination of native plant species

Soil Cd addition was found to adversely affect germination ofAndropogon scoparius, Monarda fistulosa, andRudbeckia hirta. Rudbeckia germination was found to be most sensitive to soil Cd addition andAndropogon germination most tolerant (b=–.0001). Soil cadmium concentrations sufficient to reduce germination by 25% were calculated to be 30 and 46 g Cd/g soil forRudbeckia andAndropogon respectively.Contribution from Purdue University Agricultural Experiment Station, West Lafayette, Indiana 47907. AES Journal No. 7594. This work was supported by federal funds from the National Science Foundation — RANN Program.     

Heavy metal composition of polysomal fractions following cadmium challenge

Endogeneous levels of zinc and copper were found to be 1.2±0.1×10⁻² and 0.3±0.1×10⁻² μg/A260 unit, respectively, in polysomal fractions from control animals; cadmium, however, was undetectable. In experimental animals (injected with cadmium) zinc, copper, and cadmium were found in polysomal fractions isolated by two different methods. One hour after a cadmium injection there was a rise in both the zinc and copper content of the polysomal fractions, which then declined steadily to below control levels by 16 h. Neither zinc nor cadmium were dialyzable from these fractions by a TRIS buffer; however, addition of 0.01M EDTA to the buffer resulted in removal of 75% of the zinc and all of the detectable cadmium. The addition of cadmium (CdCl₂) to control supernatants (adjusted to the cadmium concentration present in supernatants 6 h after in vivo exposure) resulted in metal binding to polysomal fractions in levels comparable to those observed after in vivo exposures to the metal. When cadmium was added in the form of cadmium thionein, a smaller fraction of the metal was isolated with the polysomal fraction. Cadmium bound to polysomal fractions in vivo (24 h after exposure) was sensitive to release by protease digestion, but insensitive to release by ribonuclease digestion.     

Detecting cadmium during ultrastructural characterization of hepatotoxicity

BackgroundThe threat of cadmium (Cd), which is the cause of itai-itai disease in Japan, is still complicated and confusing, especially for digestive system, such as liver disease. One of the most keys of this problem is demonstrating that the hepatotoxicity is indeed induced by Cd. Therefore, we attempt detecting Cd at microscale during ultrastructural imaging of liver tissue.Methods12 rats were divided randomly into two experimental groups: control and Cd-treated. Treated rats were intraperitoneal injected with 1 mg/kg body weight cadmium chloride (CdCl₂) for 4 weeks (5 P.M each day for 6 days/week). At the end of the exposure period, liver tissue samples were processed into ultrathin sections for analysis of advanced analytical transmission electron microscopy and X-ray energy dispersive spectroscopy (TEM/X-EDS) investigations. Ultrastructural images and X-ray energy dispersive spectrum were acquired at microscale.ResultsCd can cause changes in the structure of the organelle, including the collapse of the membrane structure in the cell, the destruction of the internal structure of the organelle, the mitochondrial swelling, the expansion of the endoplasmic reticulum, and the appearance of inclusions. Cadmium bioaccumulation is detected in the mitochondria at microscale by TEM/X-EDS, which is the visual evidence of morphological changes of mitochondria related to Cd.ConclusionThe combination of detailed ultrastructure and microscale X-ray energy dispersive spectroscopy (X-EDS) characterization of cadmium hepatotoxicity demonstrate that cadmium indeed leads to mitochondrial damage, which is helpful for further investigation of the pathological mechanism of cadmium hepatotoxicity.     

Alleviation of Cadmium Toxicity to <i>Medicago Truncatula</i> by AMF Involves the Changes of Cd Speciation in Rhizosphere Soil and Subcellular Distribution

Arbuscular mycorrhizal fungi (AMF) can improve plant tolerance to several abiotic stresses, including heavy metals, drought or salinity exposure. However, the role of AMF in alleviation of soil cadmium (Cd)-induced toxicity to plants is still largely unknown. In this study, Cd speciation in soil and subcellular distribution of Cd were used to characterize the roles of application AM fungi in the alleviation of Cd toxicity in alfalfa plants. Our results showed that the addition of Glomus mosseae in Cd contaminated soil (10 mg/Kg) significantly increased soil pH, cation exchange capacity (CEC) and organic matter in rhizosphere soil with Medicago truncatula L., and then account for significantly decreased contents of exchangeable and carbonate-bounded Cd speciation in rhizosphere soil, indicating alleviation of plant toxicity by reduction of bioavailable fractions of Cd. Although there is no significant difference found in Cd accumulation by roots and shoots respectively between Cd and AM-Cd treatments, more portion of Cd was recorded compartmentalization in cell wall fraction of both root and shoot in treatment of Cd with AM application, indicating alleviation of Cd toxicity to plant cell. Herein, application of AM fungi in Cd treatments performed to inhibit the appearance of Cd toxicity symptoms, including the improvement of leaf electrolyte leakage, root elongation, seedling growth and biomass. This information provides a clearer understanding of detoxification strategy of AM fungi on Cd behavior with development and stabilization of soil structure and subcellular distribution of plant.     

Elucidating Cd-mediated distinct rhizospheric and in planta ionomic and physio-biochemical responses of two contrasting Zea mays L. cultivars

Cadmium (Cd) in soil–plant system can abridge plant growth by initiating alterations in root zones. Hydroponics and rhizoboxes are useful techniques to monitor plant responses against various natural and/or induced metal stresses. However, soil based studies are considered more appropriate in order to devise efficient food safety and remediation strategies. The present research evaluated the Cd-mediated variations in elemental dynamics of rhizospheric soil together with in planta ionomics and morpho-physio-biochemical traits of two differentially Cd responsive maize cultivars. Cd-sensitive (31P41) and Cd-tolerant (3062) cultivars were grown in pots filled with 0, 20, 40, 60 and 80 µg/kg CdCl₂ supplemented soil. The results depicted that the maize cultivars significantly influenced the elemental dynamics of rhizosphere as well as in planta mineral accumulation under applied Cd stress. The uptake and translocation of N, P, K, Ca, Mg, Zn and Fe from rhizosphere and root cell sap was significantly higher in Cd stressed cv. 3062 as compared to cv. 31P41. In sensitive cultivar (31P41), Cd toxicity resulted in significantly prominent reduction of biomass, leaf area, chlorophyll, carotenoids, protein contents as well as catalase activity in comparison to tolerant one (3062). Analysis of tolerance indexes (TIs) validated that cv. 3062 exhibited advantageous growth and efficient Cd tolerance due to elevated proline, phenolics and activity of antioxidative machinery as compared to cv. 31P41. The cv. 3062 exhibited 54% and 37% less Cd bio-concentration (BCF) and translocation factors (TF), respectively in comparison to cv. 31P41 under highest Cd stress regime. Lower BCF and TF designated a higher Cd stabilization by tolerant cultivar (3062) in rhizospheric zone and its potential use in future remediation plans.