Cell damage and apoptosis in the hepatopancreas of Eriocheir sinensis induced by cadmium

Time-Dependent Hormetic Response of Soil Alkaline Phosphatase Induced by Cd and the Association with Bacterial Community Composition

Hormetic dose-response that involved Cd in soils is increasingly paid attentions for risk assessment of Cd toxicity, but insufficient studies were conducted to define the temporary modification of soil enzyme and the potential microbial responses. The present study chooses soil alkaline phosphatase (ALP) as endpoint to uncover the time-dependent hormetic responses to low doses of Cd and its association with bacterial community composition. The results showed that addition of 0.01-3.0 mg kg^-1 Cd significantly increased ALP's activities with maximum stimulatory magnitude of 11.4-27.2%, indicating a typical hormesis. The response started at 12 h after Cd addition and maintained about 24 h. This demonstrated that the hormetic response is time-dependent and transient. Changes of soil bacterial community composition showed that, at 6 h, relative abundances (RAs) of Proteobacteria and Firmicutes at phylum and Pontibacter, Bacillaceae-Bacillus, Bacillaceae1-Bacillus, and Paenisporosarcina at genus significantly correlated with ALP's activities at 12-36 h (P < 0.05). This suggests that soil bacteria likely showed an earlier response to Cd and potentially contributes to the subsequent soil enzyme's hormesis. In addition, it was found that Gram-negative bacteria other than Gram-positive bacteria are prone to exhibiting a hormetic response under Cd stress. Our findings provide much insight into ecotoxicological risk assessment for soil Cd pollution.

Ammonia toxicity in the mud crab (Scylla paramamosain): The mechanistic insight from physiology to transcriptome analysis

Ammonia is a major aquatic environmental pollutants. However, the underlying molecular mechanism of ammonia-induced toxicity is not fully understood. In this study, we investigated the physiological response and molecular mechanism in mud crab (Scylla paramamosain) exposed to the acute total ammonia (30 mg L^-1) for 48 h. The results shown that ammonia exposure induced oxidative stress, and subsequently led to cytological damage and DNA damage. Transcriptome analysis was applied to investigate the key genes and pathways involved in the responses to ammonia exposure. A total of 722 differentially expressed genes (DEGs) (526 up-regulated and 196 down-regulated) were identified. DEGs mainly involved in pathways including metabolism, cellular processes, signal transduction and immune functions. Additionally, transcriptome analysis revealed that ATM/p53-Caspase3 pathway involved in apoptosis induced by ammonia stress. These results provided a new insight into the mechanism of the potential toxic effects of ammonia on crustaceans.

Effects of single and mixture exposure of cadmium and copper in apoptosis and immune related genes at transcriptional level on the midge Chironomus riparius Meigen (Diptera, Chironomidae)

Metals and heavy metals are natural contaminants with an increasing presence in aquatic ecosystems as a result of human activities. Although they are mixed in the water, research is usually focused on analyzing them in isolation, so there is a lack of knowledge about their combined effects. The aim of this work was to assess the damage produced by mixtures of cadmium and copper, two frequent metals used in industry, in the harlequin midge Chironomus riparius (Diptera). The effects of acute doses of cadmium and copper were evaluated in fourth instar larvae by analyzing the mRNA levels of six genes related to apoptosis (DRONC, IAP1), immune system (PO1, Defensin), stress (Gp93), and copper homeostasis (Ctr1). DRONC, Ctr1, and IAP1 transcripts are described here for first time in this species. Individual fourth instar larvae were submitted to 10 μM, 1 μM and 0.1 μM of CdCl₂ or CuCl_2, and mixture. The employed individuals came from different egg masses. Real-time PCR analysis showed a complex pattern of alterations in transcriptional activity for two genes, DRONC and Gp93, while the rest of them did not show any statistically significant differences. The effector caspase DRONC showed upregulation with the highest concentration tested of the mixture. In case of gp93, chaperone involved in regulation of immune response, differences in expression levels were found with 1 and 10 μM Cu and 0.1 and 10 μM of mixtures, compared to control samples. These results suggest that mixtures affect the transcriptional activity differently and produce changes in apoptosis and stress processes, although it is also possible that Gp93 alteration could be related to the immune system since it is homologous to human protein Gp96, which has been related with Toll-like receptors. In conclusion, cadmium and copper mixtures can affect the population by affecting the ability of larvae to respond to the infection and the apoptosis, an important process in the metamorphosis of insects.

Roles of three Es-Caspases during spermatogenesis and Cadmium-induced apoptosis in Eriocheir sinensis

Functions of Caspases remain obscure in Crustacea. We studied the existence and participations of apoptosis-related factors in Eriocheir sinensis testis. Three Es-Caspases (Es-Caspase 3/ 7/ 8) in E. sinensis were cloned and characterized. We observed that three es-caspases mRNA had specific expression patterns during spermiogenesis, with weak signal around the nucleus and invaginated acrosomal vesicle in early-stage spermatids, became stronger in middle-stage, finally focused on the acrosomal tube and nucleus in mature sperm. We then investigated the immunostaining intensity and positional alterations of Es-Caspase 3, Es-Caspase 8 and p53 during spermatogenesis, which were correlated with the differential tendencies of cells to undergo apoptosis and specific organelles shaping processes. After apoptotic induction by Cadmium, Es-Caspase 8 increased gradually, while Es-Caspase 3 increased firstly and then decreased, Es-p53 initially decreased and then increased. These results implies that Es-Caspase 3/ Es-Caspase 8/ p53 may play roles in Cadmium-induced apoptosis during spermatogenesis, and Caspase 8-Caspase 3-p53 pathway may interact with extrinsic or intrinsic pathways to regulate the destiny of sperm cells. Our study revealed the indispensable roles of Caspases during spermatogenesis and the possible molecular interactions in response to the Cadmium-induced apoptosis in E. sinensis, which filled the gap of apoptotic mechanisms of crustacean.

Methylmercury, cadmium and arsenic(III)-induced toxicity, oxidative stress and apoptosis in Pacific red snapper leukocytes

Methylmercury (MeHg), cadmium (Cd) and arsenic (As(III)) are among the most toxic metals in aquatic systems that have been associated with multiple animal and human health problems. This study investigated cytotoxic, oxidative stress, and apoptosis effects on fish leukocytes following their exposure to metals. A preliminary study indicated that leukocytes exposed to MeHg at a concentration of 0.01 mM, Cd at 0.05 mM, and As(III) at 2 mM showed a time-dependent cell viability reduction (around 40%), so they were selected for further experiments. To evaluate the effect of MeHg, Cd and As(III) on Pacific red snapper Lutjanus peru, we measured cytotoxicity, reactive oxygen species, antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT)), nitric oxide production, apoptosis-related and immune-related genes on head-kidney and spleen leukocytes following exposure to MeHg (0.01 mM), Cd (0.05 mM) and As(III) (2 mM) for 30 min and 2 h. Reactive oxygen species (ROS) generation highly increased in time-dependent doses in head-kidney leukocytes compared with the control group. Regarding antioxidant activity, SOD increased significantly in leukocytes exposed to any heavy metals after two h. Expressly, CAT activity decreased in those leukocytes exposed to Cd and As(III). Apoptotic function genes (Casp-2, Casp-3, and Casp-7) strongly up-regulated after heavy metal exposure, but Cd was more toxic. Finally, granzyme A and perforin 1 strongly up-regulated in leukocytes exposed to MeHg and As(III) compared with the control group. Our data showed that MeHg, Cd, and As(III) might have been cytotoxic and induced oxidative stress and apoptosis with possible biological consequences in fish.

Effects of chronic lead and cadmium exposure on the oriental river prawn (Macrobrachium nipponense) in laboratory conditions

During the past decade, the total population and overall reproductive performance of the oriental river prawn (Macrobrachium nipponense) in the Anzali international wetland and its basin rivers has been severely reduced. This seems to be caused by an increase in heavy metal pollution from industrial wastewaters. We investigated the effects of chronic levels of lead (Pb) and cadmium (Cd) on reproductive success, hemato-immunology, crustacean hyperglycemic hormone (cHH), Pb/Cd bioaccumulation and histopathology of hepatopancreas of oriental river prawn. The present study was separately carried out using four chronic treatments for Pb (0 (control), 0.024, 0.072 and 0.12 μM/l) and Cd (0 (control), 0.026, 0.053 and 0.08 μM/l) in experimental tanks during 60 days. The broodstock were fed by commercial shrimp diet, ad libitum, twice a day. The results revealed that reproductive activities ceased when Pb levels were 0.072 and 0.12 μM/l and also when Cd levels reached 0.08 μM/l. At 0.024 μM/l Pb, 0.026 and 0.053 μM/l Cd, the prawns showed initial reproductive activity but after spawning, the egg-clutches were found detached from the pleopods of the brood females. Hemato-immunology results showed that by increasing the Pb and Cd concentrations, large granular hemocyte (LGH) and cHH values also increased. However, small granular hemocyte (SGH) count was inversely affected. A significant increase in mortality (P < 0.05) was observed as both Pb and Cd concentrations increased. Histological observations are indicative of increased necrosis, lumen size, melanization, vacuolation and abnormal lumen shape, as the heavy metals concentrations increased. In conclusion, obtained results can help to elucidate effects of Pb and Cd on freshwater decapod crustaceans reproductive performance and related physiological parameters.

Cadmium-induced genome-wide DNA methylation changes in growth and oxidative metabolism in Drosophila melanogaster

Background

Cadmium (Cd)-containing chemicals can cause serious damage to biological systems. In animals and plants, Cd exposure can lead to metabolic disorders or death. However, for the most part the effects of Cd on specific biological processes are not known. DNA methylation is an important mechanism for the regulation of gene expression. In this study we examined the effects of Cd exposure on global DNA methylation in a living organism by whole-genome bisulfite sequencing (WGBS) using Drosophila melanogaster as model.

Results

A total of 71 differentially methylated regions and 63 differentially methylated genes (DMGs) were identified by WGBS. A total of 39 genes were demethylated in the Cd treatment group but not in the control group, whereas 24 showed increased methylation in the former relative to the latter. In most cases, demethylation activated gene expression: genes such as Cdc42 and Mekk1 were upregulated as a result of demethylation. There were 37 DMGs that overlapped with differentially expressed genes from the digital expression library including baz, Act5C, and ss, which are associated with development, reproduction, and energy metabolism.

Conclusions

DNA methylation actively regulates the physiological response to heavy metal stress in Drosophila in part via activation of apoptosis.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5688-z) contains supplementary material, which is available to authorized users.

Antioxidative status, immunological responses, and heat shock protein expression in hepatopancreas of Chinese mitten crab, Eriocheir sinensis under the exposure of glyphosate

As a broad-spectrum herbicide, glyphosate was extensively utilised in China for several decades. The contradiction between glyphosate spraying and crab breeding in the rice-crab co-culture system has become more obvious. In this study, the antioxidative status and immunological responses of Chinese mitten crab, Eriocheir sinensis, under sublethal exposure of glyphosate were investigated by detecting the antioxidative and immune-related enzyme activity, acetylcholinesterase (AChE) activity and relative mRNA expression of heat shock proteins (HSPs) in hepatopancreas. The results showed that high concentrations of glyphosate (44 and 98 mg/L) could induce significant alteration of superoxide dismutase (SOD), peroxidase (POD), acid phosphatase (ACP), alkaline phosphatase (AKP), and phenoloxidase (PO) activities by first rising then falling during the exposure. However, AChE activity in all treatments including 4.4 mg/L was inhibited markedly after 6 h of exposure. In addition, the relative mRNA expression of HSP 60, HSP 70, and HSP 90 was significantly upregulated at both 48 h and 96 h. These results revealed that glyphosate has a prominent toxic effect on E. sinensis based on antioxidative and immunological response inhibition and AChE activity reduction even at the lowest concentration of 4.4 mg/L, and a protective response by upregulation of HSPs was carried out by the species to ease the environmental stress.

Effects of cadmium exposure on antioxidant enzymes and histological changes in the mud shrimp Austinogebia edulis (Crustacea: Decapoda)

The trace metal cadmium (Cd) is a toxic pollutant known to induce oxidative stress and other sublethal to lethal effects on aquatic organisms. We exposed the marine mud shrimp Austinogebia edulis to Cd concentrations of 0, 0.5, and 5 mg/kg for up to 4 days (24, 48, 72, 96 h). We studied the activity of antioxidant enzymes in the hepatopancreas, gill, and muscle of A. edulis. Antioxidant enzymes (SOD, CAT, and GPx) decreased with increasing Cd concentration and extended exposure time in these three organs of the mud shrimp A. edulis. Increasing Cd concentration led to an increase in ROS and resulted ultimately in membrane lipid peroxidation at higher Cd concentrations. Significant damage of the hepatopancreas of A. edulis was noticed at higher concentrations of Cd, showing damages like the disappearance of epithelial cell boundaries, detachment of cells from the basal lamina, cellular swelling, necrosis, and reduction of glycogen. In conclusion, Cd caused oxidative damage by reducing the activities of antioxidant enzymes and by damaging the tissue structure in major organs of the mud shrimp A. edulis.

Ivermectin induces cell cycle arrest and apoptosis of HeLa cells via mitochondrial pathway

OBJECTIVES

The aim of study was to investigate the anticancer activities of Ivermectin (IVM) and the possible mechanisms in cells level via cell proliferation inhibition, apoptosis and migration inhibition in model cancer cell HeLa.

MATERIALS AND METHODS

The MTT assay was used to study the inhibitory effect of IVM on the proliferation of Hela cells, and the cell cycle was analysed by flow cytometry. The neutral comet assay was used to study the DNA damage. The presence of apoptosis was confirmed by DAPI nuclear staining and flow cytometry. Changes in mitochondrial membrane potential and reactive oxygen species (ROS) levels were determined using Rhodamine 123 staining and DCFH-DA staining. Western blot analysis for apoptosis-related proteins was carried out. We use scratch test to analyse the antimigration potential of IVM.

RESULTS

Ivermectin can inhibit the viability of HeLa cells significantly. In addition, treatment with IVM resulted in cell cycle arrest at the G1/S phase which partly account for the suppressed proliferation. Typical apoptosis morphological changes were shown in IVM treatment cells including DNA fragmentation and chromatin condensation. At the same time, the results of flow cytometry analysis showed that the number of apoptotic cells increased significantly with the increase of IVM concentration. Moreover, we observed that the mitochondrial membrane potential collapses and the ratio of Bax/Bcl-2 in the cytoplasm increases, which induces cytochrome c release from the mitochondria to the cytoplasm, activates caspase-9/-3 and finally induces apoptosis. We also found that IVM can significantly increase intracellular ROS content. At the same time, we determined that IVM can significantly inhibit the migration of HeLa cells.

CONCLUSIONS

Our experimental results show that IVM might be a new potential anticancer drug for therapy of human cancer.

MhMAPK4 from Malus hupehensis Rehd. decreases cell death in tobacco roots by controlling Cd2+ uptake

Cadmium (Cd) induces cell death in plant roots. Mitogen-activated protein kinase (MAPK) plays a role in the regulation of cell death induced by Cd in plant roots. In this study, MhMAPK4 was isolated from the roots of Malus hupehensis. Subcellular localization showed that the MhMAPK4 protein was located in the cell membrane and cytoplasm and is a transmembrane protein that is characterized by hydrophily. The expression of MhMAPK4 in the roots of M. hupehensis was up-regulated by Cd sulfate and Cd chloride. Phenotypic comparison under Cd stress showed that the growth of wild-type (WT) tobacco was lower than the transgenic lines overexpressing MhMAPK4. The fresh weight and the root length of WT also was lower than that of the transgenic tobacco. The net Cd2+ influx in the tobacco roots was decreased by the overexpression of MhMAPK4, as was root Cd accumulation. The recovery time of the Cd2+ influx to stable state in the transgenic tobacco was also shorter than the WT. The expression of iron-regulated transporter 1 (NtIRT1) and natural resistance associated macrophage protein 5 (NtNRAMP5) was relatively low in the transgenic lines under Cd stress. Cell death and apoptosis in the tobacco roots was reduced following the overexpression of MhMAPK4. The activity of vacuolar processing enzyme (VPE) and the transcript level of VPE in the transgenic tobacco was lower than that of WT under Cd stress. In addition, the electrolyte leakage and malondialdehyde and hydrogen peroxide contents in the transgenic tobacco were lower than those of WT, whereas the antioxidant enzyme activity and expression were higher. These results suggest that MhMAPK4 regulates Cd accumulation by mediating Cd2+ uptake by the roots, and controls Cd-caused cell death by adjusting VPE activity.

Do trace metal contamination and parasitism influence the activities of the bioturbating mud shrimp Upogebia cf. pusilla?

Mud shrimp are considered as among the most influential ecosystem engineers in marine soft bottom environments because of their significant bioturbation activity and their high density. These organisms play a key role on the physical structure of sediments through intense sediment reworking activity and also deeply influence geochemical properties of sediments via frequent bioirrigation events. The influence that mud shrimp have on the environment is related to the magnitude of bioturbation processes and subsequently depends on their physiological condition. In natural environments, several factors act together and influence the well-being of organisms. Among them, the deleterious role of parasites on the physiology and the behavior of their host is well established. Aquatic organisms are also subject to pollutants released by anthropogenic activities. However, the effect of both stressors on the fitness and bioturbation activity of mud shrimp has never been investigated yet. We conducted a 14-day ex-situ experiment to evaluate the influence of trace metal contamination (cadmium Cd) and parasitism infestation on the gene expression (molecular endpoint) and sediment reworking activity (behavioral endpoint) of the mud shrimp Upogebia cf. pusilla. At completion, mud shrimp exhibited substantial Cd bioaccumulation, with parasitized organisms showing a significantly lower contaminant burden than unparasitized specimens. Cadmium contamination induces modifications of gene expression in both unparasitized and parasitized organisms. We report an antagonistic effect of both stressors on gene expression, which cannot be fully explained by a lower Cd bioaccumulation. At the behaviour level, parasitism seems to reduce the sediment reworking activity of mud shrimp, while Cd contamination appears to stimulate this activity. This study highlights that the effects of multiple stressors may be quite different from the effects of each stressor considered individually. It should also motivate for more studies evaluating the influence of multiple stressors on different endpoints encompassing various levels of organization.

Bioaccumulation, tissue distribution and joint toxicity of erythromycin and cadmium in Chinese mitten crab (Eriocheir sinensis)

The bioaccumulation of erythromycin (ETM) and cadmium (Cd) in Chinese mitten crab (Eriocheir sinensis) and subsequent toxicity on pathological changes and enzymatic activities were investigated during 21-day exposure to ETM, Cd, and Cd + ETM mixture. The bioaccumulation of Cd and ETM residues in crab tissues decreased as gill > hepatopancreas > muscle > ovary, with higher Cd bioaccumulation than ETM. The highest Cd bioaccumulation in crab reached 1.15 mg/g dry weight in gill and 461.29 μg/g in hepatopancreas, on the 14th day of Cd treatment. Cd exposure promoted the bioaccumulation of ETM in four tissues. ETM exposure caused tubular vacuolization in epithelial and edema and degeneration of hepatic ducts in hepatopancreas, and disconnected gill epithelial layer and indistinctly cellular structure in gill. During Cd exposure, mitochondria acted as a main biomarker to identify the damage, including reduced and swollen mitochondria, and broken mitochondrial structure. Moreover, Chinese mitten crab showed defence capability against ETM and Cd exposure by physiological adjustment of metabolic enzymes glutathione S-transferase activity.

Cardiac-specific Mst1 deficiency inhibits ROS-mediated JNK signalling to alleviate Ang II-induced cardiomyocyte apoptosis

Apoptosis is associated with various myocardial diseases. Angiotensin II (Ang II) plays a central role in the pathogenesis of RAAS‐triggered cardiac apoptosis. Our previous studies showed that mammalian Ste20‐like kinase 1 (Mst1) aggravates cardiac dysfunction in cardiomyocyte under pathological conditions, but its role in Ang II‐mediated cardiomyocyte apoptosis is not known. We addressed this in the present study by investigating whether cardiac‐specific Mst1 knockout can alleviate Ang II‐induced cardiomyocyte apoptosis along with the underlying mechanisms. In vitro and in vivo experiments showed that Ang II increased intracellular reactive oxygen species (ROS) production and cardiomyocyte apoptosis; these were reversed by administration of the ROS scavenger N‐acetylcysteine and by Mst1 deficiency, which suppressed c‐Jun N‐terminal kinase (JNK) phosphorylation and downstream signaling. Interestingly, Mst1 knockout failed to alleviate Ang II‐induced phosphorylation of extracellular signal‐regulated kinase 1/2, and inactivated apoptosis signal‐regulating kinase1 (ASK1) by promoting its association with thioredoxin (Trx), which reversed the Ang II‐induced activation of the ASK1–JNK pathway and suppressed Ang II‐induced cardiomyocyte apoptosis. Thus, cardiac‐specific Mst1 knockout inhibits ROS‐mediated JNK signalling to block Ang II‐induced cardiomyocyte apoptosis, suggesting Mst1 as a potential therapeutic target for treatment of RAAS‐activated heart failure.

Deoxynivalenol decreased the growth performance and impaired intestinal physical barrier in juvenile grass carp (Ctenopharyngodon idella)

Deoxynivalenol (DON) is one of the most common mycotoxin contaminants of animal feed worldwide and brings significant threats to the animal production. However, studies concerning the effect of DON on fish intestine are scarce. This study explored the effects of DON on intestinal physical barrier in juvenile grass carp (Ctenopharyngodon idella). A total of 1440 juvenile grass carp (12.17 ± 0.01 g) were fed six diets containing graded levels of DON (27, 318, 636, 922, 1243 and 1515 μg/kg diet) for 60 days. This study for the first time documented that DON caused body malformation in fish, and histopathological lesions, oxidative damage, declining antioxidant capacity, cell apoptosis and destruction of tight junctions in the intestine of fish. The results indicated that compared with control group (27 μg/kg diet), DON: (1) increased the reactive oxygen species (ROS), malondialdehyde (MDA) and protein carbonyl (PC) content, and up-regulated the mRNA levels of Kelch-like-ECH-associated protein 1 (Keap1: Keap1a but not Keap1b), whereas decreased glutathione (GSH) content and antioxidant enzymes activities, and down-regulated the mRNA levels of antioxidant enzymes (except GSTR in MI) and NF-E2-related factor 2 (Nrf2), as well as the protein levels of Nrf2 in fish intestine. (2) up-regulated cysteinyl aspartic acid-protease (caspase) -3, -7, -8, -9, apoptotic protease activating factor-1 (Apaf-1), Bcl2-associated X protein (Bax), Fas ligand (FasL) and c-Jun N-terminal protein kinase (JNK) mRNA levels, whereas down-regulated B-cell lymphoma-2 (bcl-2) and myeloid cell leukemia-1 (Mcl-1) mRNA levels in fish intestine. (3) down-regulated the mRNA levels of ZO-1, ZO-2b, occludin, claudin-c, -f, -7a, -7b, -11 (except claudin-b and claudin-3c), whereas up-regulated the mRNA levels of claudin-12, -15a (not -15b) and myosin light chain kinase (MLCK) in fish intestine. All above data indicated that DON caused the oxidative damage, apoptosis and the destruction of tight junctions via Nrf2, JNK and MLCK signaling in the intestine of fish, respectively. Finally, based on PWG, FE, PC and MDA, the safe dose of DON for grass carp were all estimated to be 318 μg/kg diet.

Influence of the bioturbator Upogebia cf. pusilla on trace metal remobilization: Does parasitism matter?

Marine sediments are an important source of contaminants since they are susceptible to be remobilized to the water column. By modifying the physical and biogeochemical characteristics of sediments, bioturbation can influence contaminants remobilization. Within bioturbators, mud shrimp are considered as among the most influential organisms in marine soft-bottom environments. The physiological state of mud shrimp can be impaired by bopyrid parasites. The present study aims to evaluate the influence of bopyrid-uninfested and bopyrid-infested mud shrimp on sediment contaminants resuspension. Through a 14-days ex-situ experiment we showed a moderate effect of mud shrimp on contaminant remobilization compared to molecular diffusion without the bioturbator. Conversely, parasite presence significantly impaired contaminant bioaccumulation in mud shrimp and interfered with genetic expression. The weak effect of mud shrimp on contaminant remobilization may be due to trace metal accumulation and thus we suggested to evaluate the influence of contaminants on activities of bioturbating species.

Biochemical and transcriptional analyses of cadmium-induced mitochondrial dysfunction and oxidative stress in human osteoblasts

Cadmium (Cd) accumulation is known to occur predominantly in kidney and liver; however, low-level long-term exposure to Cd may also result in bone damage. Few studies have addressed Cd-induced toxicity in osteoblasts, particularly upon cell mitochondrial energy processing and putative associations with oxidative stress in bone. To assess the influence of Cd treatment on mitochondrial function and oxidative status in osteoblast cells, human MG-63 cells were treated with Cd (up to 65 μM) for 24 or 48 h. Intracellular reactive oxygen species (ROS), lipid and protein oxidation and antioxidant defense mechanisms such as total antioxidant activity (TAA) and gene expression of antioxidant enzymes were analyzed. In addition, Cd-induced effects on mitochondrial function were assessed by analyzing the activity of enzymes involved in mitochondrial respiration, membrane potential (ΔΨm), mitochondrial morphology and adenylate energy charge. Treatment with Cd increased oxidative stress, concomitantly with lipid and protein oxidation. Real-time polymerase chain reaction (qRT-PCR) analyses of antioxidant genes catalase (CAT), glutathione peroxidase 1 (GPX1), glutathione S-reductase (GSR), and superoxide dismutase (SOD1 and SOD2) exhibited a trend toward decrease in transcripts in Cd-stressed cells, particularly a downregulation of GSR. Longer treatment with Cd (48 h) resulted in energy charge states significantly below those commonly observed in living cells. Mitochondrial function was affected by ΔΨm reduction. Inhibition of mitochondrial respiratory chain enzymes and citrate synthase also occurred following Cd treatment. In conclusion, Cd induced mitochondrial dysfunction which appeared to be associated with oxidative stress in human osteoblasts.

Alterations of antioxidant indexes and inflammatory cytokine expression aggravated hepatocellular apoptosis through mitochondrial and death receptor-dependent pathways in Gallus gallus exposed to arsenic and copper

In this study, we sought to investigate the effects of sub-chronic exposure of arsenic (As) and copper (Cu) on oxidative stress, inflammatory response, and mitochondria and death receptor apoptosis pathways in chicken liver. Seventy-two 1-day-old male Hy-line chickens were treated with basal diet, 30 mg/kg arsenic trioxide (As₂O₃), or/and 300 mg/kg copper sulfate (CuSO₄) for 4, 8, and 12 weeks. Study revealed that exposure to As or/and Cu undermined the antioxidant function and increased lipid peroxidation. Worse yet, liver cell swollen, vacuolar degeneration, and inflammatory cell infiltration were accompanied by an increase of the nuclear factor-κB (NF-κB) and its downstream inflammation-related genes after exposure to As or/and Cu. Furthermore, mitochondria swollen and chromatin condensation were found in As and Cu groups, and hepatocyte nuclear membrane rupture and markedly increased (P < 0.01) apoptosis index were observed in As combined with Cu group. Meanwhile, the transcription and protein expression levels of Bcl-2-associated X protein (Bax), p53, cytochrome c (Cyt c), and caspase-3, 8, 9 were upregulated and B cell lymphoma-2 (Bcl-2) was downregulated in As, Cu, and As + Cu groups in the liver tissues (P < 0.05, P < 0.01). Our results indicated that exposure to As or/and Cu could lead to oxidative stress, inflammatory response, and tissue damage and aggravate hepatocellular apoptosis through mitochondrial and death receptor-dependent pathways in chicken liver. And As and Cu showed a possible synergistic relationship in liver damage.

Hormetic effects of Cd on alkaline phosphatase in soils across particle-size fractions in a typical coastal wetland

Hormetic responses in soil ecosystem are increasingly reported recently. Soil enzymes are involved in almost all biochemical reactions, but insufficient investigations were conducted to define its hormetic responses. The objective of this study is to investigate the hormetic responses across soil particle-size fractions with cadmium (Cd) as a stressor and alkaline phosphatase (ALP) as a potential endpoint. Soils were treated by adding CdCl₂·2.5H₂O solution with 0, 0.003, 0.03, 0.3, 3.0 and 30.0mg·kg^-1 of Cd, respectively. A low-power ultrasonic method was used to separate the bulk soil into 0.1-2, 2-63, 63-200 and 200-2000μm fractions. In 2-63μm, ALP activity at doses of 0.3-3.0mg·kg^-1 of Cd was significantly higher than that of CK (0.0mg·kg^-1 of Cd), showing a typical U-shaped dose-response with the amplitude of 72.3-118.6%. Similarly, ALP activity at 0.003-0.3mg·kg^-1 of Cd was 36.4-66.1% higher than that of CK in 63-200μm. However, no similar phenomenon was observed in 0.1-2 and 200-2000μm fractions. This suggested that low doses of Cd induced the hormetic responses of soil ALP, particularly in 2-63 and 63-200μm. In addition, analysis of the microbial community structure and diversity indicates that, at genus level, the relative abundance (RA) of Gillisia at 0.03-0.3mg·kg^-1 of Cd was significantly higher than that of CK with the amplitude of 3.7-37.5% in 2-63μm. The similar responses were observed that the RA of Pontibacter at 0.003-0.03mg·kg^-1 of Cd was 4.0-85.4% higher than that of CK in 63-200μm. This showed that Gillisia and Pontibacter possibly contribute to the hormetic responses of soil ALP when low contents of Cd presented in soils. This study will provide a good insight into the hormetic phenomenon at soil ecosystem scales.