Short-term Cadmium Exposure Research Articles

Proteomic analysis of toxic effects of short-term cadmium exposure on goat livers.

Food safety is closely related to environmental pollution. It is worth noting that the long-term accumulation of Cd, a toxic heavy metal, in animals may pose a threat to human health through food chain. Previous studies have found that Cd exposure may cause liver metabolic disorders of black goats, but the mechanism of its impact on liver proteome of goats has not been widely studied. Therefore, in this study, ten male goats (Nubian black goat × native black goat) were exposed to Cd via drinking water containing CdCl2 (20mg Cd·kg-1·BW) for 30days (five male goats per group). Blood physiology and liver antioxidant indices in black goats were determined and differentially expressed proteins (DEPs) in the livers of Cd-exposed goats were profiled by using TMT-labelled proteomics. It was found that plasma Hb and RBC levels as well as PCV values were decreased, liver SOD, GSH-Px, T-AOC and CAT levels were decreased, and MDA level was increased in Cd-treated goats, and 630 DEPs (up 326, down 304) in the livers of Cd-treated goats. Proteomics analysis revealed that Cd exposure affected glutathione metabolism and drug metabolism-cytochrome P450. We identified GP×2, GSTM3, and TBXAS1 as potential protein markers of early Cd toxicity in goats. This study provided theoretical basis for early diagnosis of Cd poisoning in goats.

Effects of cadmium on mitochondrial structure and function in different organs: studies on the soil centipede Lithobius forficatus (Myriapoda, Chilopoda)

Mitochondria are organelles that play a crucial role in cell physiology, cell death, and aging. They are among the first responders to different stressors that originate from the environment. Cadmium as a heavy metal affects different levels of body organization: from organs through tissues and cells to organelles. Based on our previous research results, we decided to check how the exposure to cadmium affects the functioning of mitochondria in different organs of soil living centipede Lithobius forficatus. The activity of mitochondria in somatic and germ cells has been analyzed using transmission electron microscopy (TEM), confocal microscopy, and flow cytometry. Changes in the mitochondrial membrane potential and mitochondrial dismutase (MnSOD) activity in relation to the accumulation of reactive oxygen species (ROS) caused by cadmium exposure have been studied. Individuals were divided into 3 experimental groups depending on cadmium concentration in soil. Changes in mitochondrial ultrastructure caused by cadmium are tissue-dependent and associated with an increase of ROS levels. The system of ROS and MnSOD activation works more efficiently in the case of gonads than in the digestive system. While the short-term cadmium exposure alters the fine structure of both the somatic and germ-line cells in gonads, the long-term cadmium exposure causes mitochondrial ultrastructure regeneration.

Transcriptomic profile of oyster Crassostrea gigas hemocyte after short-term cadmium exposure and bacteria stimulation

Oyster Crassostrea gigas, is considered as a useful environmental indicator since it is widely distributed along the intertidal zone whereby it tends to accumulate cadmium and is always exposed to various pathogen agents. However, its molecular responses to both cadmium and pathogen stimulation remain unclear. In the present study, transcriptome data of hemocytes from oysters were analyzed to reveal specific molecular responses of oyster to cadmium or cadmium/bacteria stimulation. A total of 21591, 22872 and 20107 genes were detected in the BLANK, Cd24h and Cd/Bac24h group, respectively. Among them, there were 685 differentially expressed genes collected in the comparison of Cd24h versus BLANK. GO analysis of these genes found that sixteen terms into the Molecular Function category displayed transporter activities, and were all over-enrichment by cadmium exposure, whereas twelve terms into Biological Process category involved mainly in metabolic process of the various cellular components and two terms into Cellular Component category were all under-enrichment. The 330 immune responsive genes were shared by two gene lists of CdBac24h versus BLANK and CdBac24h versus Cd24h, and seven out of thirty terms in GO analysis were related to the immune process. Further annotation of these genes from the KEGG database revealed fourteen pathways, including two nervous system related pathways, arachidonic acid pathway, four immune pathways, MAPK cascade and other four cell signaling pathways, and two energy related pathways. Twenty-two differentially expressed genes were identified to responsive to both cadmium exposure and bacteria stimulation, but in different expression patterns, suggesting that bilateral responsive genes, such as alkaline phosphatase and sodium and chloride-dependent glycine transporter gene, could be candidate biomarkers for early warning of cadmium pollution. The present results collectively indicated that a profound neuro-endocrine-immune regulatory network was activated in response to cadmium and bacteria stimulation in oyster C. gigas, and the expression pattern of some cadmium responsive genes may be either reversed or strengthened by bacteria stimulation. The results provide knowledge on the transcriptomic response profile of oyster after short-term cadmium exposure and bacteria stimulation, which would be useful for future studies on stress response mechanism of mollusc, and some cadmium-bacteria responsive genes may be explored as potential biomarkers for monitoring marine pollution.

Root Hair Single Cell Type Specific Profiles of Gene Expression and Alternative Polyadenylation Under Cadmium Stress.

Transcriptional networks are tightly controlled in plant development and stress responses. Alternative polyadenylation (APA) has been found to regulate gene expression under abiotic stress by increasing the heterogeneity at mRNA 3′-ends. Heavy metals like cadmium pollute water and soil due to mining and industry applications. Understanding how plants cope with heavy metal stress remains an interesting question. The Arabidopsis root hair was chosen as a single cell model to investigate the functional role of APA in cadmium stress response. Primary root growth inhibition and defective root hair morphotypes were observed. Poly(A) tag (PAT) libraries from single cell types, i.e., root hair cells, non-hair epidermal cells, and whole root tip under cadmium stress were prepared and sequenced. Interestingly, a root hair cell type-specific gene expression under short term cadmium exposure, but not related to the prolonged treatment, was detected. Differentially expressed poly(A) sites were identified, which largely contributed to altered gene expression, and enriched in pentose and glucuronate interconversion pathways as well as phenylpropanoid biosynthesis pathways. Numerous genes with poly(A) site switching were found, particularly for functions in cell wall modification, root epidermal differentiation, and root hair tip growth. Our findings suggest that APA plays a functional role as a potential stress modulator in root hair cells under cadmium treatment.

Short-term cadmium exposure induces gas exchanges, morphological and ultrastructural disturbances in mangrove Avicennia schaueriana young plants

Mangroves have been subject to more metal contamination, including cadmium (Cd). This study evaluated if a relatively short Cd exposure may induce metabolic, morphological and ultrastructural cell disturbance in Avicennia schaueriana. Cd induced evident constraints to seedlings since there was reduction in leaf gas exchanges and the plants did not survive for more than 10 days at a higher Cd exposure in controlled conditions. The highest Cd accumulation was observed in roots and gradually less in stem and leaves. Cadmium induced lignin deposition was observed in xylem cells of all vegetative organs. Intense sclerification in xylem cells, endoderm and change in the hypoderm organization were also detected. Cadmium clearly induced chloroplast deformities with ruptures of its membranes, thylakoids and core and provoked cytoplasm disorganization. These metal constraints under natural conditions for long term can lead to the accumulation of cellular and metabolic damages and jeopardize seedlings establishment and local biodiversity.

Short-term cadmium exposure induces stress responses in frog (Pelophylax bergeri) skin organ culture

There have been a few studies on the negative effects of pollutants on amphibian skin, the first structural barrier that interacts with the environment and its potential contaminants. In this study an ex vivo skin organ culture from the amphibian Pelophylax bergeri was used to evaluate cell stress responses induced by short-term exposure to cadmium (Cd), a toxic heavy metal known to be an environmental hazard to both humans and wildlife. Histopathological studies were carried out on skin explants using light microscopy and changes in the expression of stress proteins, such as Metallothionein (MT) and Heat shock proteins (HSPs), were investigated by Real-time RT-PCR. Results revealed that amphibian skin reacts to Cd-induced stress by activating biological responses such as morphological alterations and dose- and time-dependent induction of Mt and Hsp70 mRNA expression, suggesting their potential role as biomarkers of exposure to Cd. This work provides a basis for a better understanding of the tissue-specific responses of amphibian skin as a target organ to Cd exposure and its in vitro use for testing potentially harmful substances present in the environment.

Evaluation of the Effect of Short-Term Cadmium Exposure on Brackish Water <i>Shrimp-Palaemonetes africanus</i>

This study evaluated the effect of short-term cadmium exposure on brackish water shrimp-Palaemonetes africanus. Tests were carried out by exposing the shrimps to the test solutions containing variousconcentrations of the cadmium (0, 0.1, 1.0, 4.0, 6.0, 8.0, 10.0, and 100.0) mg/l using the semi-static agitation test procedure. Mortality was recorded at 2, 4, 6, 8, 10, 12, 14 and 16 hours exposure periods. Test results indicated that the brackish water juvenile shrimp, Palaemonetes africanus were sensitive to the cadmium solution especially at concentration above 4.0mg/l. Though no death was recorded after 16hrs for 0.1mg/l, 1.0mg/l and 4.0mg/l respectively, however, for 6mg/l, 60% mortality was recorded after 4hrs and 100% after 8hrs, for 8mg/l, 20% mortality was recorded after 2hrs, 60% after 4hrs, 80% after 6hrs and 100% mortality after 8hrs respectively, for10mg/l, 40% mortality was recorded after 2hrs and 100% after 4hrs and 100% mortality was recorded for 100mg/l after 2hrs. The LC50 value calculated using Arithmetic Method of Karber was 5.0mg/l. It is therefore evident that the effects of acute toxicity of cadmium are concentration-related; the greater the concentration, the greater the effect.

Oxidative stress in duckweed ( Lemna minor L.) caused by short-term cadmium exposure

The mechanisms of plant defence against cadmium toxicity have been studied by short-term exposure of Lemna minor L. (common duckweed) to concentrations of CdCl 2 ranging from 0 to 500 μM. High accumulation of cadmium was observed (12,320 ± 2155 μg g −1 at 500 μM CdCl 2), which caused a gradual decrease of plant growth, increased lipid peroxidation, and weakened the entire antioxidative defence. Total glutathione concentration decreased significantly; however, the concentration of oxidized glutathione remained stable. The responses of four antioxidant enzymes showed that catalase was the most inhibited after CdCl 2 exposure, ascorbate peroxidase and guaiacol peroxidase moderately, and glutathione reductase least. The total antioxidative potential revealed an induced antioxidative network at 0.1 μM CdCl 2 (137 ± 13.2% of the control) and its reduction to only 47.4 ± 4.0% of the control at higher cadmium concentrations. The possible application of the examined biomarkers in ecotoxicological research is discussed.

Respiratory and hematological response of tench, Tinca tinca (L.) to a short-term cadmium exposure

The effects of 3 h exposure to 96hLC50 of cadmium (4.5 mg dm−3) on oxygen consumption rate, and hematological parameters (RBC, WBC, erythrocyte and leukocyte pattern) of juvenile tench were evaluated. Oxygen consumption significantly decreased beginning from 24 h postexposure, and remained reduced until the end of the experiment (96 h postexposure). RBC gradually increased, together with the percentage of juvenile cells in circulation. On the other hand, cadmium induced damage to the red cells – the share of cellular anomalies significantly increased with time postexposure. They included abnormal cell shape, vacuolization, swelling, chromatin disintegration in the nucleus, and nucleus indentation. The exposed fish showed a gradual and significant decrease in WBC without a shift of lymphocyte/neutrophil proportion. No significant changes in thrombocyte count occurred. The results show that short-term exposure to cadmium reduced fish energetic metabolism, and suppressed immune abilities. The symptoms gradually developed after the end of exposure, and no recovery took place until␣96 h.

Environmental cadmium exposure and metabolic responses of the Nile tilapia, Oreochromis niloticus

The contamination of water by metal compounds is a worldwide environmental problem. This study was undertaken to evaluate the impact of short-term cadmium exposure on metabolic patterns of the freshwater fish Oreochromis niloticus. The fish were exposed to 320, 640, 1280 and 2560 μg/l sublethal concentrations of Cd ++ (CdCl 2) in water for 7 days. The specific activities of the enzymes phosphofructo kinase (PFK-E.C.2.7.1.11.), lactate dehydrogenase (LDH-E.C.1.1.1.27.) and creatine kinase (CK-E.C.2.7.3.2.) were decreased in white muscle after cadmium treatments, indicating decreases in the capacity of glycolysis in this tissue. Cadmium exposure induced increased glucose concentration in white muscle of fish. On the other hand, cadmium exposure at sublethal concentrations increased phosphofructo kinase and LDH in red muscle of fish. Cadmium significantly decreased total protein concentrations in liver and white muscle regardless of tissue glycogen levels. The data suggest that cadmium acts as a stressor, leading to metabolic alterations similar to those observed in starvation.

Effects of cadmium on gametogenesis in the sea star Asterias rubensL.

The effects of cadmium on gametogenesis in the sea star Asterias rubens were studied after short-term exposure to 200 μg Cd/l or after long-term exposure to 25 μg Cd/l under semi-field conditions. Short-term exposure of female sea stars to cadmium caused a reduction in ovary growth. Part of the oocytes obtained from Cd-exposed females showed no germinal vesicle breakdown (GVBD) upon stimulation with 1-methyladenine, while the other part needed more time to complete GVBD than oocytes from unexposed sea stars. Histological study of the ovaries of exposed females revealed a growth delay in part of the oocytes. No effect of short-term cadmium exposure was found on growth of testes. Long-term exposure of sea stars to 25 μg Cd/l caused a delay in ovary growth. This effect was clear after five months of exposure, but at the end of the reproductive cycle the difference had become smaller. No effects were observed on the overall biochemical composition of the ovaries or oocytes. The cadmium concentration in oocytes of exposed sea stars was only about 30% lower than the level found in whole gonads. Gonadal growth in male sea stars was not affected by long-term cadmium exposure. The cadmium level in testes of Cd-exposed males was about a factor 6 lower than in ovaries. The cadmium concentration in spermatozoa was comparable to that of whole testes.

Modulation of murine T and B cell reactivity after short-term cadmium exposure in vivo.

This study assessed early effects of short-term Cd exposure on T and B cell responsiveness. Spleen cells from mice injected s.c. with a daily dosage of 1 mg, 0.33 mg, or 0.11 mg Cd (as CdCl2) per kg body weight for 5 days were examined for their potential to generate alloreactive T cells in a mixed lymphocyte reaction (MLR) and for mitogen reactivity to concanavalin A (Con A) in vitro. Spleen cells from the same mice were also assayed for the total number of IgM- and IgG-secreting B cells. Whereas alloreactivity was reduced, mitogen response to Con A was not different from controls or was even enhanced. The decrease in allogeneic MLR was dependent on the injected Cd dosage. No difference in susceptibility to Cd-induced effects was observed among the mouse strains tested, i.e. BALB/c, DBA/2, C57BL/6, and C3H/He. Co-cultivation of spleen cells, obtained from Cd-treated mice that exhibited deficient T cell reactivity, with splenic responder cells from untreated mice resulted in dose-dependent suppression of the normal MLR. These results indicate that the harmful effects of Cd on the immune system include the inhibition of antigen-specific T cell responses by the activation of an antigen non-specific suppressor system. In contrast to the suppressed allogeneic MLR, the same spleen cell populations showed augmented numbers of IgM- and IgG-antibody producing cells.

The effect of age on cadmium retention in organs of hamsters.

Age difference of cadmium retention was investigated in hamsters after a short term cadmium exposure. Three types of organs were identified in relation to cadmium retention, i. e., the liver and testes retained an increasing amount of cadmium with increasing age, the kidney and heart showed a gradual decrease in the retention after a transient increase in young ages and the bone showed no retention. These changes seemed to be related to the de novo synthesis of metallothionein in the organ.