Life and death of <Emphasis Type="Italic">Trypanosoma cruzi</Emphasis> in presence of metals

Trypanosoma cruzi has many molecules that need metallic elements to work, allowing cell invasion and the establishment of infection, causing Chagas disease. Nonetheless, knowledge regarding how the parasites address metals and maintain homeostasis is lacking. To study this relationship, zinc, cadmium and mercury were chosen. Epimastigote, trypomastigote and intracellular forms of T. cruzi were incubated with these metals for different times and at different concentrations. In general, epimastigotes were the most sensitive and trypomastigotes the most resistant to metals. ZnCl₂ induced low toxic effects to all parasite forms. Although the parasites were very sensitive to the toxic effects of CdCl₂ and HgCl₂, pretreatment with ZnCl₂ decreased the death rate. The trypomastigotes pretreated with CdCl₂ were unable to infect the host cells, and the treated intracellular forms were damaged after 2 h of incubation, when the toxic effects were poorly reverted. New insights on metal toxicity mechanisms are provided, helping to understand how metallic ions influence the parasite’s biochemical and physiological processes.     

Physiological responses and antioxidant enzyme changes in <Emphasis Type="Italic">Sulla coronaria</Emphasis> inoculated by cadmium resistant bacteria

Plant growth promoting bacteria (PGPB) may help to reduce the toxicity of heavy metals on plants growing in polluted soils. In this work, Sulla coronaria inoculated with four Cd resistant bacteria (two Pseudomonas spp. and two Rhizobium sullae) were cultivated in hydroponic conditions treated by Cd; long time treatment 50 µM CdCl₂ for 30 days and short time treatment; 100 µM CdCl₂ for 7 days. Results showed that inoculation with Cd resistant PGPB enhanced plant biomass, thus shoot and root dry weights of control plants were enhanced by 148 and 35% respectively after 7 days. Co-inoculation of plants treated with 50 and 100 µM Cd increased plant biomasses as compared to Cd-treated and uninoculated plants. Cadmium treatment induced lipid peroxidation in plant tissues measured through MDA content in short 7 days 100 µM treatment. Antioxidant enzyme studies showed that inoculation of control plants enhanced APX, SOD and CAT activities after 30 days in shoots and SOD, APX, SOD, GPOX in roots. Application of 50 µM CdCl₂ stimulated all enzymes in shoots and decreased SOD and CAT activities in roots. Moreover, 100 µM of CdCl₂ increased SOD, APX, CAT and GPOX activities in shoots and increased significantly CAT activity in roots. Metal accumulation depended on Cd concentration, plant organ and time of treatment. Furthermore, the inoculation enhanced Cd uptake in roots by 20% in all treatments. The cultivation of this symbiosis in Cd contaminated soil or in heavy metal hydroponically treated medium, showed that inoculation improved plant biomass and increased Cd uptake especially in roots. Therefore, the present study established that co-inoculation of S. coronaria by a specific consortium of heavy metal resistant PGPB formed a symbiotic system useful for soil phytostabilization.     

Effects of the administration of cadmium and zinc on the concentration of zinc in the thymus of rats

The zinc content of thymus glands of male Wistar rats has been determined during five weeks of treatment with ZnCl₂ and CdCl₂, and compared with a group of control rats. THymus gland extracts were chromatographed on columns of Sephadex G-75 and the zinc content of the one hundred fractions obtained were determined by atomic absorption spectrophotometry. The rats treated with ZnCl₂ showed an increase in the thymus concentration of zinc bound to high and low molecular weight proteins. The rats treated with CdCl₂ showed an increase in zinc concentration, as opposed to the control group, during the first three weeks of treatment, and thereafter show a toxic effect of cadmium on the gland, with ulterior regression of the latter, and a decrease in the concentration of zinc.     

Serum metabonomics analysis of quercetin against the toxicity induced by cadmium in rats

This study aimed to investigate the protective effect of quercetin against the toxicity induced by chronic exposure to low levels of cadmium in rats by an ultra performance liquid chromatography mass spectrometer. Rats were randomly divided into six groups as follows: control group (C), low dose of quercetin group (Q1: 10 mg/kg·bw), high dose of quercetin group (Q2: 50 mg/kg·bw), cadmium chloride group (D), low dose of quercetin plus cadmium chloride group (DQ1), and high dose of quercetin plus cadmium chloride group (DQ2). Cadmium chloride (CdCl₂) was administered to rats by drinking water ad libitum in a concentration of 40 mg/L. The final amount of CdCl₂ ingested was estimated from the water consumption data to be 4.85, 4.91, and 4.89 mg/kg·bw/day, for D, DQ1, and DQ2 groups, respectively. After a 12‐week treatment, the serum samples of rats were collected for metabonomics analysis. Ten potential biomarkers were identified for which intensities were significantly increased or reduced as a result of the treatment. These metabolites included isorhamnetin 4′‐O‐glucuronide, 3‐indolepropionic acid, tetracosahexaenoic acid, lysophosphatidylcholine (LysoPC) (20:5), lysoPC (18:3), lysophosphatidylethanolamine (LysoPE) (20:5/0:0), bicyclo‐prostaglandin E2, sulpholithocholylglycine, lithocholyltaurine, and glycocholic acid. Results indicated that quercetin exerted a protective effect against cadmium‐induced toxicity by regulating lipid and amino acid metabolism, enhancing the antioxidant defense system and protecting liver and kidney function.     

Zinc Dyshomeostasis in Cardiomyocytes after Acute Hypoxia/Reoxygenation

This study aimed to assess the protective roles of polysaccharides from Agaricus blazei Murill (ABP) against cadmium (Cd)-induced damage in chicken livers. A total of 80 Hy-Line laying chickens (7 days old) were randomly divided into four groups (n = 20). Group I (control) was fed with a basic diet and 0.2 ml saline per day, group II (Cd-treated group) was fed with a basic diet containing 140 mg/kg cadmium chloride (CdCl₂) and 0.2 ml saline per day, group III (Cd + ABP-treated group) was fed with a basic diet containing 140 mg/kg CdCl₂ and 0.2-ml ABP solution (30 mg/ml) per day via oral gavage, and group IV (ABP-treated group) was fed with 0.2-ml ABP solution (30 mg/ml) per day via oral gavage. The contents of Cd and malondialdehyde (MDA), the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX), the messenger RNA (mRNA) levels of inflammatory cytokines and heat shock proteins (HSPs), the protein levels of HSPs, and the histopathological changes of livers were evaluated on days 20, 40, and 60. The results showed that Cd exposure resulted in Cd accumulating in livers and inhibiting the activities of antioxidant enzymes (SOD and GSH-PX). Cd exposure caused histopathological damage and increased the MDA content, the mRNA levels of inflammatory cytokines (TNF-α, IL-1β, and IL-6) and HSPs (HSP27, HSP40, HSP60, HSP70, and HSP90) and the protein levels of HSPs (HSP60, HSP70, and HSP90). ABP supplementation during dietary exposure to Cd reduced the histopathological damage and decreased the contents of Cd and MDA and the expression of inflammatory cytokines and HSPs and improved the activities of antioxidant enzymes. The results indicated that ABP could partly ameliorate the toxic effects of Cd on chicken livers.     

Antioxidant capacity and cadmium accumulation in parsley seedlings exposed to cadmium stress

Parsley (Petroselinum hortense L.) plants cultivated under controlled conditions were exposed to different doses of cadmium to investigate the antioxidant capacity and cadmium accumulation in the samples. Two-months-old parsley seedlings were treated with four different concentrations of CdCl₂ (0, 75, 150, and 300 μM) for fifteen days. Cadmium level in leaves increased significantly by increasing the Cd contamination in the soil. Total chlorophyll and carotenoid content declined considerably with Cd concentration. Cd treatment caused a significant increase lipid peroxidation in tissue of leaf. Superoxide dismutase activity (SOD, EC 1.15.1.1) increased partially at 75 and 150 μM CdCl₂ concentrations whereas the activity decreased at 300 μM CdCl₂. Catalase (CAT, EC 1.11.1.6) and ascorbate peroxidase (APX, EC 1.11.1.11) activities were reduced by Cd application. Total phenolic compound amount increased significantly with increasing Cd concentration, as ferric reduction power, superoxide anion radical, and DPPH˙ free radical scavenging activities elevated slightly by the concentration. These results suggest that antioxidant enzymes activities were repressed depending on accumulation of cadmium in leaves of parsley while the non-enzymatic antioxidant activities slightly increased.     

Physiological and Biochemical Mechanisms Preventing Cd Toxicity in the New Hyperaccumulator <Emphasis Type="Italic">Abelmoschus manihot</Emphasis>

Abelmoschus manihot, an ornamental plant, was examined for phytoremediation purposes in accordance with the ability to accumulate cadmium and physiological mechanisms of cadmium tolerance. A net photosynthetic rate (A _N) glasshouse experiment for 60 days was conducted to investigate the influence of different cadmium amounts (0–100 mg kg^?1) on the growth, biomass, photosynthetic performance, reactive oxygen species (ROS) production, antioxidative enzyme activities, Cd uptake and accumulation of A. manihot. Exposure to cadmium enhanced plant growth even at 100 mg kg^?1, without showing symptoms of visible damage. The cadmium concentration of shoots (stems or leaves) and roots was more than the critical value of 100 mg kg^?1 and reached 126.17, 185.26 and 210.24 mg kg^?1, respectively. BCF values of A. manihot plants exceeded the reference value 1.0 for all the Cd treatments, and TF values were greater than 1 at 15–60 mg kg^?1 Cd treatment. The results also showed that cadmium concentrations of 60 mg kg^?1 or less induced a significant enhancement in plant net photosynthetic rate (A _N), stomatal conductance (G _s), transpiration rate (T _r), photosynthetic pigments and F _v/F _m. These parameters were slightly decreased at the higher concentration (100 mg kg^?1). The ROS production (O₂ ^?, H₂O₂) and antioxidative response including SOD, CAT and POD were significantly enhanced by increasing cadmium. These results suggest that A. manihot can be considered as a Cd-hyperaccumulator and the hormetic effects may be taken into consideration in remediation of Cd contamination soil.     

In vitro studies on protective effect of Glycyrrhiza glabra root extracts against cadmium-induced genetic and oxidative damage in human lymphocytes

Cadmium is a modern environmental contaminant that is toxic and carcinogenic. Glycyrrhiza glabra is a traditional medicinal herb which grows in the various parts of the World. Recent studies demonstrated that G. glabra has antifungal, antimicrobial, antioxidant, and powerful antiinflammatory features. The purpose of this study was to investigate the genetic safety of extracts from G. glabra and its effects on cadmium (as CdCl₂) induced genotoxicity. Therefore we evaluated the capability of G. glabra extract to inhibit the rate of micronucleus (MN), sister chromatid exchange (SCE) formations induced by CdCl₂. Moreover, to assess the effects of G. glabra on cell viability and oxidative status, we performed 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and total antioxidant capacity (TAC) assays. Our results showed that there were significant increases (P < 0.05) in both SCE and MN frequencies of cultures treated with CdCl₂ (5 ppm) as compared to controls. However, co-application of G. glabra extract (5, 10 and 20 ppm) and CdCl₂ resulted in decreases of MN and SCE rates as compared to the group treated with CdCl₂ alone. Again, the results of MTT and TAC assays clearly indicated dose dependent ameliorative effects of G. glabra extracts against CdCl₂ toxicity. In conclusion, this study demonstrated for the first time that G. glabra extracts provided increased resistance of DNA against CdCl₂ induced genetic and oxidative damage in human lymphocytes. So, the risk on target tissues of CdCl₂ could be reduced and ensured early recovery from its toxicity.     

Effects of interaction between65Zn,cadmium, and copper in rats

Distribution and retention of zinc in the presence of cadmium and copper was studied in rats exposed repeatedly to these metals. The experiment was performed on white rats of the Wistar strain. The animals were divided into four groups/five rats each: 1)⁶⁵ZnCl₂; 2)⁶⁵ZnCl₂+CdCl₂; 3)⁶⁵ZnCl₂+CuCl₂; and 4) control group. Rats were administered sc every other day for two weeks:⁶⁵ZnCl₂−5 mg Zn/kg; CdCl₂−0,3 Cd/kg; and CuCl₂−2 mg Cu/kg. The zinc content was measured in rat tissues by γ-counting. Effect of Cd and Cu on subcellular distribution of zinc in the kidney and liver and on the level of metallothionein were also examined. Whole body retention of zinc under the influence of cadmium was lower than that observed in animals treated with zinc alone. However, copper increased twofold the whole body retention of zinc. Cadmium elevated the accumulation of zinc only in the kidneys nuclear fraction and liver soluble fraction. In the kidneys and liver, copper elevated the accumulation of zinc, in the nuclear, mitochondrial, and soluble fractions. The level of metallothionein-like proteins (MT) in the kidneys after a combined supply of zinc and copper was significantly increased with respect to the group of animals treated with zinc alone. These results indicated complex interactions between cadmium, copper, and zinc that can affect the metabolism of each of the metals.     

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.     

Cadmium Alters the Concentration of Fatty Acids in THP-1 Macrophages

Fatty acid composition of human immune cells influences their function. The aim of this study was to evaluate the effects of known toxicant and immunomodulator, cadmium, at low concentrations on levels of selected fatty acids (FAs) in THP-1 macrophages. The differentiation of THP-1 monocytes into macrophages was achieved by administration of phorbol myristate acetate. Macrophages were incubated with various cadmium chloride (CdCl₂) solutions for 48 h at final concentrations of 5 nM, 20 nM, 200 nM, and 2 μM CdCl₂. Fatty acids were extracted from samples according to the Folch method. The fatty acid levels were determined using gas chromatography. The following fatty acids were analyzed: long-chain saturated fatty acids (SFAs) palmitic acid and stearic acid, very long-chain saturated fatty acid (VLSFA) arachidic acid, monounsaturated fatty acids (MUFAs) palmitoleic acid, oleic acid and vaccenic acid, and n-6 polyunsaturated fatty acids (PUFAs) linoleic acid and arachidonic acid. Treatment of macrophages with very low concentrations of cadmium (5–200 nM) resulted in significant reduction in the levels of arachidic, palmitoleic, oleic, vaccenic, and linoleic acids and significant increase in arachidonic acid levels (following exposure to 5 nM Cd), without significant reduction of palmitic and stearic acid levels. Treatment of macrophages with the highest tested cadmium concentration (2 μM) produced significant reduction in the levels of all examined FAs: SFAs, VLSFA, MUFAs, and PUFAs. In conclusion, cadmium at tested concentrations caused significant alterations in THP-1 macrophage fatty acid levels, disrupting their composition, which might dysregulate fatty acid/lipid metabolism thus affecting macrophage behavior and inflammatory state.     

Histochemical staining of cadmium thiolate clusters in livers of rats treated chronically with cadmium

Summary In livers of rats exposed to varying doses of CdCl₂ 80–90% of the cadmium content present in the fresh tissue is retained if these livers are fixed with a neutral or acid formalin fixative.Cadmium assays during different stages of the staining procedure for protein bound disulphides show the ability of this staining to demonstrate cadmium thiolate clusters next to disulphides. The methods described may also be useful in gaining more insight in the mechanism involved in fixation and staining procedure of some other metals.     

A prospective study of dietary and supplemental zinc intake and risk of type 2 diabetes depending on genetic variation in <Emphasis Type="Italic">SLC30A8</Emphasis>

Background

The solute carrier family 30 member 8 gene (SLC30A8) encodes a zinc transporter in the pancreatic beta cells and the major C-allele of a missense variant (rs13266634; C/T; R325W) in SLC30A8 is associated with an increased risk of type 2 diabetes (T2D). We hypothesized that the association between zinc intake and T2D may be modified by the SLC30A8 genotype.

Results

We carried out a prospective study among subjects with no history cardio-metabolic diseases in the Malmö Diet and Cancer Study cohort (N = 26,132, 38% men; 86% with genotype data). Zinc intake was assessed using a diet questionnaire and food record. During a median follow-up of 19 years, 3676 T2D cases occurred. A BMI-stratified Cox proportional hazards regression model with attained age as the time scale was used to model the association between total and dietary zinc intake, zinc supplement use, zinc to iron ratio, and risk of T2D adjusting for putative confounding factors.The median total zinc intake was 11.4 mg/day, and the median dietary zinc intake was 10.7 mg/day. Zinc supplement users (17%) had a median total zinc intake of 22.4 mg/day. Dietary zinc intake was associated with increased risk of T2D (P _trend < 0.0001). In contrast, we observed a lower risk of T2D among zinc supplement users (HR = 0.79, 95% CI 0.70–0.89). The SLC30A8 CC genotype was associated with a higher risk of T2D (HR = 1.16, 95% CI 1.07–1.24), and the effect was stronger among subjects with higher BMI (P _interaction = 0.007). We observed no significant modification of the zinc-T2D associations by SLC30A8 genotype. However, a three-way interaction between SLC30A8 genotype, BMI, and zinc to iron ratio was observed (P _interaction = 0.007). A high zinc to iron ratio conferred a protective associated effect on T2D risk among obese subjects, and the effect was significantly more pronounced among T-allele carriers.

Conclusions

Zinc supplementation and a high zinc to iron intake ratio may lower the risk of T2D, but these associations could be modified by obesity and the SLC30A8 genotype. The findings implicate that when considering zinc supplementation for T2D prevention, both obesity status and SLC30A8 genotype may need to be accounted for.

     

Metabolomics and Trace Element Analysis of Camel Tear by GC-MS and ICP-MS

Acne vulgaris is a very common skin disorder affecting human beings. There is a paucity of report on the role of heavy metals—lead (Pb) and cadmium (Cd)—globally, and trace metals—zinc (Zn) and copper (Cd)—particularly in Nigeria in the development/severity of acne vulgaris. This study is aimed to determine the blood levels of some heavy metals—cadmium and lead—and trace metals—zinc and copper—in acne vulgaris sufferers in a Nigerian population. Venous blood samples were collected from a total number of 90 non-obese female subjects consisting of 30 mild, 30 moderate and 30 severe acne vulgaris sufferers for blood Cd, Pb, Cu and Zn determination. They were age-matched with 60 females without acne vulgaris who served as the control subjects. Acne sufferers had significantly higher blood Cd and Pb (P = 0.0143 and P = 0.0001 respectively) and non-significantly different blood levels of Cu and Zn (P = 0.910 and P = 0.2140 respectively) compared to controls. There were significant progressive increases in blood levels of Cd and Pb (P = 0.0330 and P = 0.0001 respectively) and non-significant differences in the mean blood level of Cu and Zn (P = 0.1821 and P = 0.2728 respectively) from mild to moderate and severe acne vulgaris sufferers. Increases in blood Cd and Pb may play critical roles in the pathogenesis/severity of acne vulgaris, while Cu and Zn seem to play less significant roles in the development of this disorder in this environment.     

Carbonylated protein changes between active germinated embryos and quiescent embryos give insights into rice seed germination regulation

Achyranthes bidentata contains a rich source of important pharmaceutically active triterpene acids including oleanolic acid (OA) as a major one. 3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) is a key enzyme to provide mevalonate for biosynthesis of triterpene acids. In this study, in order to develop a sustainable source of OA, cell suspension cultures were established from shoot cultures of A. bidentata, and a full length cDNA encoding HMGR (designated as AbHMGR) was cloned and characterized. The cDNA contained 2078 nucleotides with a complete open reading frame of 1593 nucleotides, which was predicted to encode a peptide of 530 amino acids. Expression analysis by real-time PCR revealed that AbHMGR mRNA was abundant in A. bidentata roots, stems and leaves. When cultivated in Murashige and Skoog medium supplemented with 1.5 mg/L 1-naphthlcetic acid (NAA) and 1.5 mg/L 6-benzyladenine (6-BA), cells in suspension culture grew rapidly, yielding OA (100.9 mg/L) after 15 days. OA content in cell cultures was increased under the elicitation of methyl jasmonate (MeJA), yeast elicitor (YE) or cadmium chloride (CdCl₂). The ultrahigh production of OA was achieved to 371.8 mg/L, a 5.4-fold of the control after 2-day treatment of 0.2 mM MeJA in the cell cultures. Quantitative real-time PCR analysis showed that AbHMGR was expressed at a higher level under the elicitation of MeJA or YE. Our results suggested that OA production may be the result of the up-regulated expression of AbHMGR under the treatment of various elicitors.     

Shoot endophytic plant growth-promoting bacteria reduce cadmium toxicity and enhance switchgrass (<Emphasis Type="Italic">Panicum virgatum</Emphasis> L.) biomass

The aims of the study were to increase the biomass and to alleviate the deleterious effects of cadmium (Cd) in the switchgrass cultivars (Panicum virgatum L.) Alamo and Cave-in-Rock (CIR) under cadmium (Cd) stress using Cd-tolerant shoot endophytic plant growth-promoting bacteria (PGPB). Four shoot endophytic bacterial strains, viz. Bc09, So23, E02, and Oj24, were isolated from the above-ground parts of plants grown in a Cd-polluted soil and were successfully identified by 16S rRNA gene sequencing as Pseudomonas grimontii, Pantoea vagans, Pseudomonas veronii, and Pseudomonas fluorescens, respectively. These four strains were adapted to high CdCl₂ concentrations as they had higher Cd uptake capacities. In addition, they possessed a huge amount of growth regulatory activities e.g., indole acetic acid production, 1-aminocyclopropane-1-carboxylic acid deaminase (ACCD) activity, and phosphate solubilization. Growth particularly the height and biomass of both cultivars increased significantly in response to PGPB inoculation in the 20 µM CdCl₂ stress. The shoot biomass of the PGPB-inoculated Alamo was higher than the CIR under Cd stress. Interestingly, the level of Cd inside PGPB-inoculated plant tissues and the translocation factors were lower compared with the noninoculated Cd control plants. CIR plants exhibited higher Cd content than Alamo plants. Through confocal microscopy, green fluorescence was observed in roots and leaf tissues 2 days after the inoculation of green fluorescent protein (GFP)-labeled bacteria in Alamo, which confirmed the successful colonization of bacteria inside the plant tissues. These shoot endophytic PGPB and switchgrass interactions are useful for the sustainable biomass production of bioenergy crop in a Cd-contaminated environment.     

Tomato Jasmonic Acid-Deficient Mutant <Emphasis Type="Italic">spr2</Emphasis> Seedling Response to Cadmium Stress

The involvement of jasmonic acid (JA) in the plant response to cadmium (Cd) stress has been addressed in some publications by application experiments or analysis of endogenous contents of JA. In this study, we comparatively investigated the response of tomato wild type (WT) and its JA-deficient mutant spr2 to Cd stress aimed at clarifying the role of JA. One-month-old potted plants were exposed to CdCl₂ at final concentrations of 5, 25, and 50 mg kg^?1 in soil, respectively, for 15 days. The root and leaf Cd contents were dramatically increased, especially in the spr2 plants, in a CdCl₂ dose-effect manner. In the Cd dose-dependent inhibitory effect on plant growth, spr2 plants were more obvious than WT plants. This was also reflected by certain physiological and biochemical metabolisms. We analyzed photosynthesis-related parameters including total chlorophyll, actual efficiency of PS2, ratio of variable to maximum chlorophyll fluorescence, and net photosynthetic rate; relative water content, soluble sugar and proline contents, and starch accumulation; oxidative stress and antioxidative defense including malondialdehyde production, electrolyte leakage, H₂O₂ levels, activities of superoxide dismutase, peroxidase, and catalase, and their isoform expression profiles. The Cd-induced changes in all these parameters supported the conclusion that endogenous JA deficiency enhanced tomato seedling sensitivity to Cd. This implies that JA positively regulates the tomato plant response to Cd stress.     

Are cadmium effects on plasma gonadotropins, prolactin, ACTH, GH and TSH levels, dose-dependent?

It is well established that cadmium affects plasma levels of the pituitary hormones studied. However, whether the effects of the metal are dose dependent needs to be clarify. This work was designed to evaluate the possible changes in plasma levels of gonadotropins, prolactin, ACTH, GH and TSH after oral cadmium exposure in adult male rats. Plasma levels of these hormones were measured in adult male rats exposed to cadmium chloride (CdCl₂) in the drinking water at the doses of 5, 10, 25, 50 or 100 ppm for one month. The lower dose of cadmium increased plasma prolactin levels and higher doses of the metal (25 or 50 ppm) decreased them. There was a continuous increase of plasma ACTH levels from the lower to 25 ppm dose of CdCl₂ and decreased them after to basal values with the highest dose. Plasma GH levels were increased with the dose of cadmium of 10 ppm, although the doses of 5, 25 and 50 ppm decreased them. Plasma LH levels were only reduced with the dose of 50 ppm of CdCl₂, whereas those of FSH increased. Plasma TSH levels were increased with the doses of 5, 25 and 100 ppm of CdCl₂. Cadmium concentration increased in pituitary with the doses of 125, 50 and 100 ppm of CdCl₂. These data suggest that cadmium differentially affects the secretory mechanisms of the pituitary hormones studied depending on the dose used. The effects of the metal on prolactin and ACTH are dose-dependent.     

Selenium mitigates cadmium-induced oxidative stress in tomato (<Emphasis Type="Italic">Solanum lycopersicum</Emphasis> L.) plants by modulating chlorophyll fluorescence,osmolyte accumulation,and antioxidant system

Pot experiments were conducted to investigate the role of selenium in alleviating cadmium stress in Solanum lycopersicum seedlings. Cadmium (150 mg L^?1) treatment caused a significant reduction in growth in terms of height and biomass accumulation and affected chlorophyll pigments, gas exchange parameters, and chlorophyll fluorescence. Selenium (10 μM) application mitigated the adverse effects of cadmium on growth, chlorophyll and carotenoid contents, leaf relative water content, and other physiological attributes. Lipid peroxidation and electrolyte leakage increased because of cadmium treatment and selenium-treated plants exhibited considerable reduction because of the decreased production of hydrogen peroxide in them. Cadmium-treated plants exhibited enhanced activity of antioxidant enzymes that protected cellular structures by neutralizing reactive free radicals. Supplementation of selenium to cadmium-treated plants (Cd + Se) further enhanced the activity of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) by 19.69, 31.68, 33.14, and 54.47%, respectively. Osmolytes, including proline and glycine betaine, increased with selenium application, illustrating their role in improving the osmotic stability of S. lycopersicum under cadmium stress. More importantly, selenium application significantly reduced cadmium uptake. From these results, it is clear that application of selenium alleviates the negative effects of cadmium stress in S. lycopersicum through the modifications of osmolytes and antioxidant enzymes.     

Protective Roles of Selenium on Nitric Oxide-Mediated Apoptosis of Immune Organs Induced by Cadmium in Chickens

Little is known about the influence of subchronic cadmium exposure on apoptosis in the immune organs of birds and the protective effects on apoptosis by selenium against cadmium. The aim of this study was to investigate the effect of subchronic cadmium exposure on nitric oxide and apoptosis in the immune organs of chicken and the protective roles of selenium against cadmium-induced apoptosis. Two hundred ten 30-day-old chickens were randomly assigned to three groups and were fed a basal diet, cadmium?+?selenium (as 150 mg of CdCl₂ per kg of diet?+?10 mg of Na₂SeO₃ per kg of diet ) or cadmium (as 150 mg of CdCl₂ per kg of diet) in basic diets for 15, 30, 45, and 60 days. Then, the production of nitric oxide, messenger RNA (mRNA level), and the activity of inducible nitric oxide synthase, ultrastructural changes, TUNEL assay, and flow cytometric analysis of apoptosis and Bcl-2 and p53 mRNA levels in the immune organs were examined. The results showed that cadmium exposure caused ultrastructural damage and increased production of nitric oxide, mRNA level, and activity of inducible nitric oxide synthase, the degree, and the number of apoptotic cells in a time-dependent manner. Cadmium exposure decreased Bcl-2 mRNA level and increased p53 mRNA level in a time-dependent manner. Selenium supplementation during dietary cadmium reduced the production of nitric oxide, the mRNA level, and activity of inducible nitric oxide synthase, ultrastructural damage, and apoptosis in the immune organs of chicken. It indicated that cadmium induced nitric oxide-mediated apoptosis of immune organs, and selenium played protective effects against cadmium-induced apoptosis in the immune organs of chickens.