Excess Zinc Supply Reduces Cadmium Uptake and Mitigates Cadmium Toxicity Effects on Chloroplast Structure, Oxidative Stress, and Photosystem II Photochemical Efficiency in Salvia sclarea Plants

Salvia sclarea L. is a Cd2+ tolerant medicinal herb with antifungal and antimicrobial properties cultivated for its pharmacological properties. However, accumulation of high Cd2+ content in its tissues increases the adverse health effects of Cd2+ in humans. Therefore, there is a serious demand to lower human Cd2+ intake. The purpose of our study was to evaluate the mitigative role of excess Zn2+ supply to Cd2+ uptake/translocation and toxicity in clary sage. Salvia plants were treated with excess Cd2+ (100 μM CdSO4) alone, and in combination with Zn2+ (900 μM ZnSO4), in modified Hoagland nutrient solution. The results demonstrate that S. sclarea plants exposed to Cd2+ toxicity accumulated a significant amount of Cd2+ in their tissues, with higher concentrations in roots than in leaves. Cadmium exposure enhanced total Zn2+ uptake but also decreased its translocation to leaves. The accumulated Cd2+ led to a substantial decrease in photosystem II (PSII) photochemistry and disrupted the chloroplast ultrastructure, which coincided with an increased lipid peroxidation. Zinc application decreased Cd2+ uptake and translocation to leaves, while it mitigated oxidative stress, restoring chloroplast ultrastructure. Excess Zn2+ ameliorated the adverse effects of Cd2+ on PSII photochemistry, increasing the fraction of energy used for photochemistry (ΦPSII) and restoring PSII redox state and maximum PSII efficiency (Fv/Fm), while decreasing excess excitation energy at PSII (EXC). We conclude that excess Zn2+ application eliminated the adverse effects of Cd2+ toxicity, reducing Cd2+ uptake and translocation and restoring chloroplast ultrastructure and PSII photochemical efficiency. Thus, excess Zn2+ application can be used as an important method for low Cd2+-accumulating crops, limiting Cd2+ entry into the food chain.

AzuR From the SmtB/ArsR Family of Transcriptional Repressors Regulates Metallothionein in Anabaena sp. Strain PCC 7120

Metallothioneins (MTs) are cysteine-rich, metal-sequestering cytosolic proteins that play a key role in maintaining metal homeostasis and detoxification. We had previously characterized NmtA, a MT from the heterocystous, nitrogen-fixing cyanobacterium Anabaena sp. strain PCC 7120 and demonstrated its role in providing protection against cadmium toxicity. In this study, we illustrate the regulation of Anabaena NmtA by AzuR (Alr0831) belonging to the SmtB/ArsR family of transcriptional repressors. There is currently no experimental evidence for any functional role of AzuR. It is observed that azuR is located within the znuABC operon but in the opposite orientation and remotely away from the nmtA locus. Sequence analysis of AzuR revealed a high degree of sequence identity with Synechococcus SmtB and a distinct α5 metal binding site similar to that of SmtB. In order to characterize AzuR, we overexpressed it in Escherichia coli and purified it by chitin affinity chromatography. Far-UV circular dichroism spectroscopy indicated that the recombinant AzuR protein possessed a properly folded structure. Glutaraldehyde cross-linking and size-exclusion chromatography revealed that AzuR exists as a dimer of ∼28 kDa in solution. Analysis of its putative promoter region [100 bp upstream of nmtA open reading frame (ORF)] identified the presence of a 12–2–12 imperfect inverted repeat as the cis-acting element important for repressor binding. Electrophoretic mobility shift assays (EMSAs) showed concentration-dependent binding of recombinant dimeric AzuR with the promoter indicating that NmtA is indeed a regulatory target of AzuR. Binding of AzuR to DNA was disrupted in the presence of metal ions like Zn2+, Cd2+, Cu2+, Co2+, Ni2+, Pb2+, and Mn2+. The metal-dependent dissociation of protein–DNA complexes suggested the negative regulation of metal-inducible nmtA expression by AzuR. Overexpression of azuR in its native strain Anabaena 7120 enhanced the susceptibility to cadmium stress significantly. Overall, we propose a negative regulation of Anabaena MT by an α5 SmtB/ArsR metalloregulator AzuR.

Toxic Effect Induced by Cadmium on Some Reproductive Parameters and the Therapeutic Role of Leaves of Lemon Verbena: الأثر السمّي المستحدث بعنصر الكادميوم على بعض المعايير التكاثرية والدور العلاجي لأوراق نبات المليسة

This study was conducted on 28 male Syrian hamsters, and the aim was to confirm the toxic effects of cadmium on the structure and function of the male reproductive system and to test the effectiveness of the alcoholic extract of the lemon verbena plant in the therapeutic of cadmium toxicity. The results of the study showed the negative effect of cadmium on some reproductive parameters of male Syrian Hamster, where treatment with cadmium (5mg/kg/day) reduced GSI% values ​​for both testis and epididymis, lowered the values ​​of testicular dimensions, testosterone concentration and some physiological parameters of the tail of the epididymis sperm and some histological measurements for testes, numbers of spermatogenesis cells, Sertoli and Leydig, cadmium treatment caused histological disorders in the testicles, compared to the control group. Dosing male hamsters with lemon verbena leaf extract at two concentrations (250,500mg/kg/day) did not lead to a clear improvement compared to the cadmium group.

Cadmium Toxicity and Reproductive Function of Males

The purpose of the review of foreign literature was to analyze current research on the effects of cadmium on male reproductive function. Results. According to the researcher data, at least 15–20% of cases of fertility decline in males fall on infertility. The etiology of this phenomenon in 50% of cases remains unknown, however, increasing environmental pollution contributes to a constant increase in male infertility. One of the most toxic pollutants is cadmium. Numerous animal model studies and human epidemiological studies indicate an adverse effect of cadmium on male fertility. Smoking is an important source of cadmium, which is absorbed into the human body. In vitro studies confirm the deleterious effects of cigarette smoke compounds on sperm motility and spermatozoon parameters. Depending on the concentration, nicotine suppresses the progressive motility of the spermatozoon parameters, starting from the lowest concentration used (1 ng/ml). Likewise, it decreases the percentage of viable spermatozoon parameters and increases the amount of spermatozoon parameters in late apoptosis with altered chromatin compactness or DNA fragmentation already after 3 hours of incubation. On average, the daily intake of cadmium in humans is 1.06 μg/kg body weight, the half-life of cadmium is more than 20-40 years, which causes its accumulation in the body. The testicles are the organ in which cadmium is stored in large quantities. Studies have shown that the testicles are extremely sensitive to cadmium because these organs are characterized by intense cellular activity, where vital spermatogenesis processes take place. Exposure to cadmium leads to reproductive tract abnormalities such as cryptorchidism and hypospadias, testicular cancer, subfertility or infertility, called testicular dysgenesis syndrome. In the genesis of the testicles during the embryonic and neonatal periods, Sertoli’s cells play a critical role, the development of which is influenced by cadmium. Exposure to cadmium (1-2 mg/kg, subcutaneously) in pregnant and lactating rats causes vacuolization of Sertoli’s cells and loss of cells in the epithelium of the seminiferous tubules in adult animals. Cadmium inhibits proliferation, induces apoptosis and DNA damage in immature Sertoli’s cells. Perinatal exposure to cadmium affects the development and function of fetal Leydig cells, which are endocrine cells in the testicle. In pregnant rats that received a single dose of cadmium (0.25, 0.5, and 1.0 mg/kg, intraperitoneally), synthesis of testosterone in the fetal tests was significantly reduced, while gene expression in cells was suppressed, and the androgen-dependent formation process was reduced. The mechanism by which cadmium mediates impaired male fertility is also associated with the production of reactive oxygen species in the testicles, which leads to oxidative stress that interferes with the development and functioning of the spermatozoon parameters. Exposure to cadmium, for both environmental and occupational reasons, can contribute to a decrease in the quality of human sperm, which confirms high toxicity of cadmium. Conclusion. Thus, in humans and other mammals, cadmium damages the male reproductive system, disrupts its structure, including the vascular system of the testicles, leads to DNA damage, inhibits functions of germ cells, leads to loss of sperm quality and quantity, sub-fertility or infertility

Putative protective effect of Cadmium chloride highdiluted solution on LLC-PK1 cell intoxicated by high concentration of this same metal: an isopathic in vitro assay.

Cadmium is an important toxic environmental heavy metal. Several studies have demonstrated that a major site of cadmium toxicity in humans and in other animals is the proximal tubule of the kidney. A well established model for nefrotoxicity is the use of in vitro technique with proximal tubule epithelial cell lines, as LLC-PK1. Herein, we have the intention to study the possible protective effect of highdiluted CdCl2 solutions. In a blinding way, LLC-PK1 cells were pre-treated with highdiluted cadmium chloride in the potencies 10 cH, 15 cH and 20cH. After 4 days, these cells have received CdCl2 in a pre-determined toxic concentration. The cell viability was assessed by MTT assay. We have identified a protective effect of two CdCl2 highdiluted solutions, 10 cH and 20 cH, when cells were intoxicated by sublethal CdCl2 concentration. The results indicate that probably the highdilutions have an expressive action on cells in sublethal intoxication.

Assessment of Cadmium Toxicity in Drinking Water of Eight Talukas of Upper Sindh

In the present study, 240 groundwater samples were collected from eight Talukas of upper Sindh. The cadmium (Cd) content was determined by atomic absorption spectrophotometer. Concentration (µg/L), Daily Intake ofMetals (DIM),Health Risk Indexes (HRI) for children and adults caused due to Cd were measured through equations of EPA and WHO. Mean concentration of Cd in different Talukas of upper Sindh was found as; Daharki (6.20 µg/L), Ubauro (7.73 µg/L), Kashmore (7.53 µg/L), Tangwani (7.73 µg/L), Garhi Khairo (6.20 µg/L), Thul (5.00 µg/L), Qambar (7.674 µg/L) and Miro Khan (7.47 µg/L). Moreover, percent contamination of each Taluka was found as, Daharki (80%), Ubauro (93%), Kashmore (93%), Tangwani (93%), Gharhi Khairo (70%), Thul (56%), Qambar (93%) and Miro Khan (93%). The DIM of Cd for adult and children was calculated the range for adults was found as; Daharki (0.00006 - 0.00036), Ubauro (0.00006 - 0.00042), Kashmore (0.00006 - 0.00036), Tangwani (0.00006 - 0.00042), Garhi Khairo (0.00003 - 0.00056), Thul (0.00003 - 0.00056), Qambar (0.00008 - 0.00039) and Miro Khan (0.00008 - 0.00039) mg/kg-d, whereas, for children DIM of Cd was found lower than adults. The HRI values show that children compared to adults are under the potential risk threat due to HRI values > 1. Therefore, it can be suggested that groundwater found in above stated areas is unsafe for drinking purposes and must be treated before consumption.

Combined application of biochar and selenium alleviates cadmium toxicity in peanuts and enriches selenium content in peanut grains.

Cadmium (Cd) pollution in soil and particularly in peanuts has attracted global concern and requires urgent attention. Selenium (Se) can alleviate Cd toxicity; however, the underlying mechanisms are not completely understood. Therefore, two varieties of peanut (Arachis hypogaea Linn.) Huayu 23 and Huayu 20 were chosen as the target crops for this study. A pot experiment was conducted to investigate the effects of two Se application methods combined with biochar on the accumulation of Cd and Se, and the best application method was identified. In addition, the role of Se in alleviating Cd toxicity in peanuts was studied. The results indicated that both Se and biochar decreased the Cd content in peanuts and alleviated Cd toxicity. However, the combined application of foliar Se and biochar significantly increased the peanut biomass by 71.50–110.46%, increased the grain yield of Huayu 23 by 0.38–0.47 fold, and Huayu 20 by 2.37–3.47 fold. Additionally, Cd content in peanut grains was decreased by 26.68–50.07%, and Se content was increased by 31.57–99.75 folds. Biochar can decrease the absorption of Cd from the soil, while Se can increase the accumulation of Cd in cell vacuoles by increasing glutathione and phytochelatin to decrease the movement of Cd into the grains. Therefore, our results indicate that the combined application of foliar Se and biochar can effectively promote the enrichment of Se in peanuts and suppress Cd toxicity.

A Review on the Effects of Cadmium Toxicity on Living Beings

Cadmium is a toxic transition heavy metal with perilous effects on the health of animals and humans by indefinite ways. It is one of the asserted carcinogens group given by IARC. There are jillion ways by which cadmium may be prevalent in the environment as the pollutant or may be through contaminated water, food or by smoking. Cadmium poisoning may be seen in the form of itai itai disease. It came in knowledge after its outbreak in Japan in 1960s after the consumption of cadmium-contaminated rice as a food source. The exposure and accumulation of cadmium may lead to numerous forms of cancer, including breast, lung, prostate and nasopharynx, pancreas and kidney cancers. It expresses its effect by formation of stress proteins that depends on the amount of exposure and time of exposure. It had shown effects on the functioning of mitochondria resulting in formation of less energy or ATP (adenosine triphosphate) and more ROS. Other effects are cell apoptosis and inhibit growth, division and carcinogenic activity in cells. The current study has been done to understand the various effects scrutinised by numerous workers.