Transcriptional regulation of glutathione biosynthesis genes, γ-glutamyl-cysteine ligase and glutathione synthetase in response to cadmium and nonylphenol in Chironomus riparius

Novel Inhibitor of Glutamate-Cysteine Ligase Catalytic Subunit against Tribolium castaneum: High-Throughout Virtual Screening, Molecular Docking and Dynamics Simulation, and Bioassay

The enzyme glutamate-cysteine ligase catalytic subunit (Gclc) is a rate-limiting enzyme in the biosynthesis of glutathione that is involved in antioxidant defense, detoxification of xenobiotics, and/or its metabolites and regulates the cell cycle and immune function. Therefore, Gclc presents an appealing target for the development of novel insecticides. In this study, we conducted high-throughput virtual screening from the ZINC20 database and identified three compounds with high binding affinity to the Tribolium castaneum Gclc (TcGclc). Ultimately, we selected ZINC000032992384 due to its superior stability and lowest binding energy, as determined through molecular dynamics simulations. Bioassay results revealed that the IC50 value of ZINC000032992384 was 19.70 μM lower than that of BSO (49.67 μM). Furthermore, the larval mortality in the ZINC000032992384 treated group was 63.8%, significantly higher than that of the controls (29.1% in the dichlorvos group and 6.4% in the acetone group). This study provides novel insights for the development of a Gclc-targeted inhibitor as a potent insecticide based on the interaction between receptors and ligands.

Transcriptomic investigation and biomarker discovery for zinc response in oysters Crassostrea gasar

In an era of unprecedented industrial and agricultural growth, metal contamination in marine environments is a pressing concern. Sentinel organisms such as the mangrove oyster Crassostrea gasar provide valuable insights into these environments' health. However, a comprehensive understanding of the molecular mechanisms underlying their response to metal exposure remains elusive. To address this gap, we reanalyzed the 454-sequencing data of C. gasar, utilizing an array of bioinformatics workflow of CDTA (Combined De Novo Transcriptome Assembly) to generate a more representative assembly. In parallel, C. gasar individuals were exposed to two concentrations of zinc (850 and 4500 μg L-1 Zn) for 48 h to understand their molecular responses. We utilized Trinotate workflow for the 11,684-CDTA unigenes annotation, with most transcripts aligning with the genus Crassostrea. Our analysis indicated that 67.3% of transcript sequences showed homology with Pfam, while 51.4% and 54.5%, respectively had GO and KO terms annotated. We identified potential metal pollution biomarkers, focusing on metal-related genes, such as those related to the GSH biosynthesis (CHAC1 and GCLC-like), to zinc transporters (ZNT2-like), and metallothionein (MT-like). The evolutionary conservation of these genes within the Crassostrea genus was assessed through phylogenetic analysis. Further, these genes were evaluated by qPCR in the laboratory exposed oysters. All target genes exhibited significant upregulation upon exposure to Zn at both 850 and 4500 μg L-1, except for GCLC-like, which showed upregulation only at the higher concentration of 4500 μg L-1. This result suggests distinct activation thresholds and complex interactions among these genes in response to varying Zn concentrations. Our study provides insights into the molecular responses of C. gasar to Zn, adding valuable tools for monitoring metal pollution in marine ecosystems using the mangrove oyster as a sentinel organism.

The glutathione biosynthesis is involved in metamorphosis, antioxidant function, and insecticide resistance in Tribolium castaneum

BACKGROUND

Reduced glutathione (GSH) synthesis is vital for redox homeostasis, cell-cycle regulation and apoptosis, and immune function. The glutamate-cysteine ligase catalytic subunit (Gclc) is the first and rate-limiting enzyme in GSH synthesis, suggesting the potential use of Gclc as a pesticide target. However, the functional characterization of Gclc, especially its contribution in metamorphosis, antioxidant status and insecticide resistance, is unclear in Tribolium castaneum.

RESULTS

In this study, we identified and cloned Gclc from T. castaneum (TcGclc) and found that its expression began to increase significantly from the late larvae (LL) stage (3.491 ± 0.490-fold). Furthermore, RNA interference-mediated knockdown of TcGclc resulted in three types of aberration (100% total aberration rate) caused by the downregulation of genes related to the 20-hydroxyecdysone (20E) pathway. This deficiency was partially rescued by exogenous 20E treatment (53.1% ± 3.2%), but not by antioxidant. Moreover, in the TcGclc knockdown group, GSH content was decreased to 62.3%, and total antioxidant capacity, glutathione peroxidase and total superoxide dismutase activities were reduced by 14.6%, 83.6%, and 82.3%, respectively. In addition, treatment with different insecticides upregulated expression of TcGclc significantly compared with a control group during the late larval stage (P < 0.01).

CONCLUSION

Our results indicate that TcGclc has an extensive role in metamorphosis, antioxidant function and insecticide resistance in T. castaneum, thereby expanding our understanding of GSH functions and providing a scientific basis for pest control. © 2024 Society of Chemical Industry.

The sulfoximine insecticide sulfoxaflor exposure reduces the survival status and disrupts the intestinal metabolism of the honeybee Apis mellifera

Honeybees (Apis mellifera) are indispensable pollinators in agricultural production, biodiversity conservation, and nutrients provision. The abundance and diversity of honeybees have been rapidly diminishing, possibly related to the extensive use of insecticides in ecosystems. Sulfoxaflor is a novel sulfoximine insecticide that, like neonicotinoids, acts as a competitive modulator of nicotinic acetylcholine receptors (nAChR) in insects. However, few studies have addressed the negative effects of sulfoxaflor on honeybees at environmentally relevant concentrations. In the present study, adult workers were fed a 50% (w/v) of sugar solution containing different concentrations (0, 0.05, 0.5 and 2.0 mg/L) of sulfoxaflor for two weeks consecutively. The survival rates, food intake, and body weight of the honeybees significantly decreased after continuous exposure at higher doses (0.5 and 2.0 mg/L) of sulfoxaflor when compared with the control. The change in the metabolites in the honeybee gut was determined using high-throughput non-targeted metabolomics on day 14 after sulfoxaflor treatment. The results revealed that 24 and 105 metabolites changed after exposure to 0.5 and 2.0 mg/L sulfoxaflor, respectively, compared with that of the control groups. A total of 12 changed compounds including pregenolone and glutathione were detected as potential biomarkers, which were eventually found to be enriched in pathways of the steroid hormone biosynthesis (p = 0.0001) and glutathione metabolism (p = 0.021). These findings provide a new perspective on the physiological influence of sulfoxaflor stress in honeybees.

Analysis of Crassostrea gasar transcriptome reveals candidate genes involved in metal metabolism

Oysters have been extensively employed for monitoring of metal pollution in dynamic aquatic ecosystems. Therefore, the use of specific biomarkers can assist in discriminating the ecotoxicological implications of different elements in such complex environments. In this study, we revisited the sequencing data of gills and digestive glands transcripts in the mangrove oyster Crassostrea gasar and generated a reference transcriptome assembly from multiple assemblers, seven in total. Overall, we were able to identify a total of 11,917 transcripts, with 86.6% of them being functionally annotated and 1.4 times more than the first annotation. We screened the annotated transcripts to identify genes potentially involved in metals' transport, storage, and detoxification. Our findings included genes related to Zn distribution in cells (Zn transporters - ZIP, ZnT), metallothionein (MT-I and MT-IV), GSH biosynthesis, Ca⁺ transporter (NCX and ATP2B), and Cu distribution in cells (ATP7, ATOX1, CCS, and laccase-like). These results provided a reference transcriptome for additional insights into the transcriptional profile of C. gasar and other bivalves to better understand the molecular pathways underpinning metal tolerance and susceptibility. The study also provided an auxiliary tool for biomonitoring metal contamination in dynamic environments as estuaries.

Epalrestat suppresses cadmium-induced cytotoxicity through Nrf2 in endothelial cells

Cadmium (Cd) is an industrial and environmental pollutant that targets the vascular endothelium. The vascular system is critically affected by Cd toxicity. Recent studies have indicated an association between Cd and vascular diseases, although the mechanisms of Cd implications in vascular diseases are not clear. The purpose of the present study was to determine whether epalrestat (EPS), which is used for the treatment of diabetic neuropathy, protects against Cd-induced cytotoxicity in bovine aortic endothelial cells (BAECs). In the present study, the effects of EPS at near-plasma concentration were examined on Cd-induced cytotoxicity in BAECs. Cd-induced cytotoxicity was suppressed by pretreatment with EPS. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key transcription factor that serves a role in regulating the expression of glutamate cysteine ligase, the rate-limiting enzyme in glutathione (GSH) synthesis. In a previous study, EPS was demonstrated to increase GSH levels in BAECs in association with the Nrf2 pathway. In the present study, EPS increased GSH levels in BAECs exposed to Cd. The protective ability of EPS against the Cd-induced cytotoxicity disappeared following Nrf2 small interfering RNA transfection. In addition, EPS affected the intracellular levels of Cd, Cd transporter ZIP8 and metallothionein. To the best of our knowledge, the current study demonstrated, for the first time, that EPS suppresses Cd-induced cytotoxicity in BAECs. The upregulation of GSH may be associated with the suppression of Cd-induced cytotoxicity by EPS. From these findings, it may be proposed that the regulation of GSH, ZIP8 and metallothionein by EPS is a promising therapeutic approach to prevent Cd-induced toxicity.

Inhibition of the glutathione biosynthetic pathway increases phytochemical toxicity to Spodoptera litura and Nilaparvata lugens

Phytochemicals are toxic to insects, but their insecticidal efficiencies are usually low compared to synthetic insecticides. Understanding the mechanism of insect adaptation to phytochemicals will provide guidance for increasing their efficacy. Reduced glutathione (GSH) is a scavenger of reactive oxygen species (ROS) induced by phytochemicals. However, in insects, the pathway of GSH biosynthesis in response to phytochemicals is unclear. We found that exposure to 0.5% indole-3-methanol (I3C), xanthotoxin, and rotenone (ROT) significantly retarded the growth of Spodoptera litura larvae. The oxidative stress in S. litura larvae exposed to phytochemicals was increased. The up-regulation of glutamate cysteine ligase but not glutathione reductase revealed that the de novo synthesis pathway is responsible for GSH synthesis in phytochemical-treated larvae. Treatment with the inhibitor (BSO) of γ-glutamylcysteine synthetase (gclc), a subunit of glutamate cysteine ligase, resulted in decreases of GSH levels and GST activities, increases of ROS levels in I3C-treated larvae, which finally caused midgut necrosis and larval death. Treatment with BSO or I3C alone did not cause larval death. The addition of GSH could partly reduce the influence of I3C and BSO on S. litura growth. Nilaparvata lugens gclc RNAi confirmed the result of BSO treatment in S. litura. N. lugens gclc RNAi significantly increased the mortality of ROT-sprayed N. lugens, in which ROS levels were significantly increased. All data indicate that gclc is involved in insect response to phytochemical treatment. Treatment with dsgclc will increase the insecticidal efficacy of plant-derived compounds.

Cadmium-induced developmental alteration and upregulation of serine-type endopeptidase transcripts in wild freshwater populations of Chironomus plumosus

Cadmium, a toxic heavy metal, is a persistent environmental contaminant with irreversible toxicity to aquatic organisms. Chironomus plumosus, a natural species, is the largest sediment-burrowing aquatic midge in freshwater environments. In this study, we evaluated developmental defects in C. plumosus resulting from Cd exposure. In C. plumosus larvae, Cd exposure induced decreased survival and growth rates, reduction of emergence rate and sex ratio, and delayed emergence, as well as elevating the incidence of split tooth deformities. To identify potential biomarker genes to assess environmental pollutants such as Cd, we identified differentially expressed genes (DEGs) in C. plumosus exposed to various Cd concentrations. Among fourteen characterized DEGs, serine-type endopeptidase (SP) and heat shock protein 70 (HSP70) genes exhibited significant upregulation in C. plumosus larvae after Cd exposure. Therefore, we evaluated SP and HSP70 responses in natural C. plumosus populations collected from three sites of a Korean river and analyzed their correlations with eighteen environmental quality characteristics using principal component analysis. The highest expression of SP and HSP70 transcripts was observed in C. plumosus populations from Yeosu in Korea, which has high concentrations of polluting heavy metals. SP transcript expression was positively correlated with concentrations of Cd, Pb, Al, Fe, NO2, and NO3. These results suggested that environmental pollutants such as Cd can impair proteolytic activity in the digestive system of C. plumosus and may ultimately induce developmental alterations. We therefore suggest SP as a potential biomarker to assess the effects of environmental pollutants in aquatic ecosystems.

Cadmium and arsenic responses in the ectomycorrhizal fungus Laccaria bicolor: glutathione metabolism and its role in metal(loid) homeostasis

Ectomycorrhizal fungi play an important role in protecting their host plant from metal(loid) stresses by synthesizing various thiol rich compounds like metallothioneins and glutathione. We investigated the effect of cadmium (Cd) and arsenic (As) stress with a specific interest on glutathione (GSH) in the ectomycorrhizal fungus Laccaria bicolor. The total GSH levels inside the cell were significantly increased with increase in external metal(loid) stress. An analysis of the transcript levels of genes responsible for GSH synthesis, γ-glutamylcysteine synthetase (Lbγ-GCS) and glutathione synthetase (LbGS), using qPCR revealed that expression of both genes increased as a function of external metal(loid) concentration. The enzyme activity of both Lbγ-GCS and LbGS were increased with increase in external Cd and As concentration. Further, the functional role of Lbγ-GCS and LbGS genes in response to Cd and As stress was studied using their respective yeast mutant strains gsh1 ^Δ and gsh2 ^Δ . The mutant strains successfully expressed the two genes resulting in wild-type phenotype restoration of Cd and As tolerance. From these results, it was concluded that GSH act as a core component in the mycorrhizal defence system under Cd and As stress for metal(loid) homeostasis and detoxification.

Joint effects of chronic exposure to environmentally relevant levels of nonylphenol and cadmium on the reproductive functions in male rockfish Sebastiscus marmoratus

Nonylphenol (NP) and Cadmium (Cd) are two common contaminants that can be detected in aquatic environments. Nevertheless, the combined toxicity of NP and Cd at environmentally relevant concentrations in aquatic organisms has not been thoroughly characterized to date. In the present study, the interactions between NP and Cd on male Sebastiscus marmoratus were studied. After 21 days of exposure, the brain aromatase activity was observed to be significantly induced by 100 ng/L NP and 40 μg/L Cd, whereas all of the concentrations of co-treatment resulted in an increase in brain aromatase activity. Additionally, NP could also reduce plasma testosterone concentration, while NP, Cd and their mixture could induce plasma 17β-estradiol (E2) concentration and VTG concentration. The interactions between NP and Cd on the reproductive physiology were antagonism. Our results also support the notion of using these indicators as biomarkers for exposure to EDCs and further extend the boundary of biomonitoring to environmental levels.

Grape skin extract mitigates tissue degeneration, genotoxicity, and oxidative status in multiple organs of rats exposed to cadmium

The aim of this study was to investigate whether grape skin extract can mitigate the noxious activities induced by cadmium exposure in multiple organs of rats. For this purpose, histopathological analysis for the liver, genotoxicity, and oxidative status in the blood and liver were investigated in this setting. A total of 20 Wistar rats weighing 250 g, on average, and 8 weeks of age were distributed into four groups (n=5) as follows: control group (nontreated group); cadmium group (Cd); and grape skin extract groups (Cd+GS) at 175 or 350 mg/l. Histopathological analysis in liver showed that animals treated with grape skin extract showed improved tissue degeneration induced by cadmium intoxication. Genetic damage was reduced in blood and hepatocytes as indicated by comet and micronucleus assays in animals treated with grape skin extract. Copper-zinc superoxide dismutase and cytochrome c gene expression increased in groups treated with grape skin extract in liver cells. Grape skin extract also reduced the 8-hydroxy-2'-deoxyguanosine levels in liver cells compared with the cadmium group. Taken together, our results indicate that grape skin extract can mitigate tissue degeneration, genotoxicity, and oxidative stress induced by cadmium exposure in multiple organs of Wistar rats.

Phenolic compounds analysis, antioxidant, and hepatoprotective effects of Periploca angustifolia extract on cadmium-induced oxidative damage in HepG2 cell line and rats

A total of five components (Catechin, Caffeic acid, Ferulic acid, Rosmarinic acid, and Amentoflavone) were identified in Periploca angustifolia leaf methanolic extract. This extract did not cause any cytotoxic effect on HepG2 cell line within the range of concentrations tested (0-400 µg mL^-1). Thus, pre-treatment with 100 µg mL^-1 of P. angustifolia leaf methanolic extract (PAE) significantly (p < .05) protective HepG2 cells against cytotoxicity induced by cadmium exposure. However, Cd-intoxication significantly (p < .05) increased alanine and aspartate amino transferases serum activities (ALT and AST) and bilirubin content by 1.85-, 1.13-, and 3.55-fold, respectively. The levels of hepatic antioxidant parameters including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were significantly (p < .05) decreased in Cd-intoxicated rats with concomitant enhancement of lipid peroxidation. Our results showed that P. angustifolia leaf methanolic extract can induce antioxidant effects and also exerts beneficial effects for the treatment of Cd-induced hepatotoxicity.

Synergistic effect of co-exposure to cadmium (II) and 4-n-nonylphenol on growth inhibition and oxidative stress of Chlorella sorokiniana

Toxicological effect of freshwater algae co-exposure to Cd and 4-n-nonylphenol (4-n-NP) was seldom reported. In the present study, Chlorella sorokiniana was selected for testing the single and combined effect of Cd and 4-n-NP by detecting the growth inhibition and oxidative stress after exposure for 48 h, 72 h, and 96 h. The combined effects were evaluated by using toxic units (TU) method and concentration addition（CA）model. The synergistic effect of mixture on algal growth inhibition was both observed at 48 h and 72 h, and the additive effect was observed at 96 h. In addition, the significant alterations of superoxide, thiobarbituric acid reactive substances and antioxidant defenses (superoxide dismutase, catalase, glutathione) have been detected. It could be observed that the mixture predominantly lead to synergistic effects in superoxide induction, and the antagonistic effects in the GSH induction. A similar trend between the superoxide induction and growth inhibition were observed, which may indicate that the oxidative effects of Chlorella sorokiniana contributed to the growth inhibition after exposure to Cd and 4-n-NP. These findings may have important implications in the risk assessments of heavy metals and endocrine disruptors in the aquatic environment.

The differential expression of Chironomus spp genes as useful tools in the search for pollution biomarkers in freshwater ecosystems

Insects of the Chironomidae family are characterized by a wide ecological diversity in freshwater ecosystems. The larvae have the physiological potential to tolerate environmental stress even when there is a low concentration of oxygen, the presence of toxic substances or when there are changes in temperature and salinity. On the other hand, it is important to consider that at a cellular level, when individual insects are exposed to environmental changes, it induces responses of groups of genes that govern the molecular mechanisms related to such tolerance. In this review, using fourth instar larvae of Chironomus spp. in natural conditions and of Chironomus columbiensis under controlled conditions, we will discuss the genetic expression of a group of genes that respond to detoxification and also the biological functions involved and impacted on by mining stressors. The study of macroinvertebrate bioindicator species and their gene expression as a result of mining activity opens a window on the search for genetic biomarkers that could be used in environmental pollution assessments in freshwater ecosystems.

The Antioxidant System in the Anhydrobiotic Midge as an Essential, Adaptive Mechanism for Desiccation Survival

One of the major damaging factors for living organisms experiencing water insufficiency is oxidative stress. Loss of water causes a dramatic increase in the production of reactive oxygen species (ROS). Thus, the ability for some organisms to survive almost complete desiccation (called anhydrobiosis) is tightly related to the ability to overcome extraordinary oxidative stress. The most complex anhydrobiotic organism known is the larva of the chironomid Polypedilum vanderplanki. Its antioxidant system shows remarkable features, such as an expansion of antioxidant genes, their overexpression, as well as the absence or low expression of enzymes required for the synthesis of ascorbate and glutathione and their antioxidant function. In this chapter, we summarize existing data about the antioxidant system of this insect, which is able to cope with substantial oxidative damage, even in an intracellular environment that is severely disturbed due to water loss.

Evolutionary consequences of historical metal contamination for natural populations of Chironomus riparius (Diptera: Chironomidae)

Populations inhabiting metal-impacted freshwater systems located nearby industrial and urban areas may be under intense selection. The present study aims to address two fundamental microevolutionary aspects of metal contamination in the midge Chironomus riparius (Meigen): Are populations inhabiting historically metal contaminated sites genetically adapted to metals? And, are populations from these sites genetically eroded? To answer these questions, C. riparius populations were sampled from three sites with well-known histories of metal contamination and three nearby-located references. Genetic adaptation to metals was investigated through acute and chronic exposures to cadmium (Cd), after rearing all populations for at least six generations under laboratory clean conditions. Genetic diversity was estimated based on the allelic variation of seven microsatellite markers. Results showed higher acute tolerance to Cd in populations originating from metal contaminated sites compared to their respective references and significant differences in two out of three pairwise comparisons. However, there was a mismatch between acute and chronic tolerance to Cd with results of the partial life-cycle tests suggesting fitness costs under control clean conditions in two metal-adapted populations. Despite no evidences of genetic erosion in populations sampled from metal contaminated sites, our results suggest genetically inherited tolerance to Cd in populations inhabiting historically contaminated sites. These findings lend support to the use of C. riparius as a model organism in evolutionary toxicology and highlight the importance of coupling measures of neutral genetic diversity with assessments of chemical tolerance of populations for a better understanding of contaminant-induced adaptation and evolutionary processes.

Molecular Characterization and Expression Analysis of P38 MAPK Gene and Protein in Aquatic Midge, Chironomus riparius (Diptera: Chironomidae), Exposed to Environmental Contaminants

P38 Mitogen-activated protein kinase (MAPK), an important signaling protein involved in various cellular processes, including stress responses, has been well characterized in model organisms. P38 has been identified in a number of insects, including the genus Drosophila; however, its homologue in Chironomus riparius has not yet been identified. In this study, we identified and characterized p38 MAPK (Crp38) gene in C. riparius using a transcriptome database that was previously generated 454 GS-FLX pyrosequencing. Comparative and phylogenetic analyses were performed using the p38 homologue of other species, such as Drosophila melanogaster, Aedes aegypti, Bombyx mori, Caenorhabditis elegans, Homo sapiens, etc. Furthermore, to test its potential as a biomarker of environmental contamination, Crp38 gene expression was analyzed upon exposure to nonylphenol (NP), silver nanoparticles (AgNPs), and cadmium (Cd). Crp38 gene expression was up- or down-regulated depending on the concentration and exposure duration of chemicals. These results show the role of Crp38 gene in defense against environmental stresses, as well as its potential use as a biomarker for various environmental pollutants. We further synthesized p38 antibody based on the predicted amino acid sequence deduced from Crp38 cDNA and, using this customized antibody, examined p38 protein expression in Cd exposed C. riparius. Although transcriptional alteration was not translated to the protein level, this result showed the possible application of a protein level functional study using cDNA sequence information from next-generation sequencing database in nonmodel organisms.

Toxicological effects of particulate matter (PM2.5) on rats: Bioaccumulation, antioxidant alterations, lipid damage, and ABC transporter activity

Previous studies have demonstrated the harmful effects of atmospheric pollutants on cardiac systems because of the presence of particulate matter (PM), a complex mixture of numerous substances including trace metals. In this study, the toxicity of PM2.5 from two regions, rural (PM2.5 level of 8.5 ± 4.0 μg m(-3)) and industrial (PM2.5 level of 14.4 ± 4.1 μg m(-3)) in Brazil, was investigated through in vivo experiments in rats. Metal accumulation and biochemical responses were evaluated after rats were exposed to three different concentrations of PM2.5 in saline extract (10× dilution, 5× dilution, and concentrated). The experimental data showed the bioaccumulation of diverse trace metals in the hearts of groups exposed to PM2.5 from both regions. Furthermore, mobilization of the antioxidant defenses and an increase in lipid peroxidation of the cardiac tissue was observed in response to the industrial and rural area PM2.5. Glutathione-S-transferase activity was increased in groups exposed to the 5× and concentrated rural PM2.5. Additionally, ATP-binding cassette (ABC) transporter activity in the cardiac tissue exposed to PM2.5 was reduced in response to the 5× dilution of the rural and industrial region PM2.5. Histological analysis showed a decrease in the percentage of cardiac cells in the heart at all tested concentrations. The results indicate that exposure to different concentrations of PM2.5 from both sources causes biochemical and histological changes in the heart with consequent damage to biological structures; these factors can favor the development of cardiac diseases.

Oxidative stress and spermatogenesis suppression in the testis of cadmium-treated Bombyx mori larvae

Bombyx mori L. (B. mori) were exposed to cadmium chloride (CdCl2) incorporated in an artificial diet (0, 6.25, 12.5, 25, and 50 mg kg(-1)) throughout the larval stage. Changes in malondialdehyde (MDA) and reduced glutathione (GSH) contents and activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px), as well as their corresponding messenger RNA (mRNA) levels in the testes of the fifth instar larvae were evaluated. Additionally, spermatozoon deformation in the testes was examined. Upon Cd treatment, the MDA content in the testes was significantly increased in a concentration-dependent manner. Cd-exposed larvae had increased levels of glutathione. Pearson's correlation analysis revealed that SOD and CAT activities were positively correlated (R (2) = 0.605, P = 0.017). The changing trends in the mRNA levels of these enzymes were not always consistent with those of enzymatic activities. Alterations in GSH-Px activities and mRNA levels were positively correlated (R (2) = 0.771, P < 0.01). Morphological analysis revealed that Cd deformed and affected the maturation of spermatozoa. Our results collectively support a relationship between Cd and alterations in the levels of antioxidant enzymes in B. mori testes.

Purple carrot extract protects against cadmium intoxication in multiple organs of rats: Genotoxicity, oxidative stress and tissue morphology analyses

The aim of this study was to investigate if purple carrot extract is able to protect against the noxious activities induced by cadmium exposure in multiple organs of rats. For this purpose, histopathological analysis, genotoxicity and oxidative status were investigated in this setting. A total of twenty Wistar rats weighing 250g on the average, and 8 weeks age were distributed into four groups (n=5), as follows: Control group (non-treated group, CTRL); Cadmium group (Cd) and Purple carrot extract groups at 400mg/L or 800mg/L. Histopathological analysis revealed that liver from animals treated with purple carrot extract improved tissue degeneration induced by cadmium intoxication. Genetic damage was reduced in blood and hepatocytes as depicted by comet and micronucleus assays in animals treated with purple carrot extract. SOD-CuZn and cytocrome C gene expression increased in groups treated with purple carrot extract. Purple carrot extract also reduced the 8OHdG levels in liver cells when compared to cadmium group. Taken together, our results demonstrate that purple carrot extract is able to protect against cadmium intoxication by means of reducing tissue regeneration, genotoxicity and oxidative stress in multiple organs of Wistar rats.

Effects of erythromycin on γ-glutamyl cysteine synthetase and interleukin-1β in hyperoxia-exposed lung tissue of premature newborn rats

OBJECTIVE

To explore the effect of erythromycin on hyperoxia-induced lung injury.

METHODS

One-day-old preterm offspring Sprague-Dawley (SD) rats were randomly divided into four groups: group 1, air + sodium chloride; group 2, air + erythromycin;group 3, hyperoxia + sodium chloride; and group 4, hyperoxia + erythromycin. At one, seven, and 14 days of exposure, glutathione (GSH) and interleukin-1 beta (IL-1 beta) were detected by double-antibody sandwich enzyme-linked immunosorbent assay (ELISA), and bicinchoninic acid (BCA) was used to detect GSH protein. γ-glutamine-cysteine synthetase (γ-GCS) mRNA was detected by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

Compared with group 1, expressions of GSH and γ-GCS mRNA in group 3 were significantly increased at one and seven days of exposure (p < 0.05), but expression of γ-GCS mRNA was significantly reduced at 14 days; expression of IL-1 beta in group 3 was significantly increased at seven days of exposure (p < 0.05), and was significantly reduced at 14 days. Compared with group 3, expressions of GSH and γ-GCS mRNA in group 4 were significantly increased at one, seven, and 14 days of exposure (p < 0.05), but expressions of GSH showed a downward trend at 14 days; expression of IL-1 beta in group 4 was significantly reduced at one and seven days of exposure (p < 0.05).

CONCLUSIONS

Changes in oxidant-mediated IL-1 beta and GSH are involved in the development of hyperoxia-induced lung injury. Erythromycin may up-regulate the activity of γ-GCS, increasing the expression of GSH, inhibiting the levels of oxidant-mediated IL-1 beta and alleviating hyperoxia-induced lung injury via an antioxidant effect.

Simultaneous determination of reduced and oxidized glutathione in tissues by a novel liquid chromatography-mass spectrometry method: application in an inhalation study of Cd nanoparticles

The paper presents the development of an advanced extraction and fast analytical LC MS/MS method for simultaneous analyses of reduced and oxidized glutathione (GSH and GSSG, respectively) in different animal tissues. The simultaneous determination of GSH and GSSG is crucial because the amount and ratio of both GSH and GSSG may be altered in response to oxidative stress, an important mechanism of toxicity. The method uses the derivatization of free thiol groups in GSH. Its performance was demonstrated for less explored tissues (lung, brain, and liver) in mouse. The combined extraction and analytical method has very low variability and good reproducibility, maximum coefficients of variance for within-run and between-run analyses under 8 %, and low limits of quantification; for GSH and GSSG, these were 0.2 nM (0.06 ng/mL) and 10 nM (6 ng/mL), respectively. The performance of the method was further demonstrated in a model experiment addressing changes in GSH and GSSG concentrations in lung of mice exposed to CdO nanoparticles during acute 72 h and chronic 13-week exposures. Inhalation exposure led to increased GSH concentrations in lung. GSSG levels were in general not affected; nonsignificant suppression occurred only after the longer 13-week period of exposure. The developed method for the sensitive detection of both GSH and GSSG in very low tissue mass enables these parameters to be studied in cases where only a little sample is available, i.e. in small organisms or in small amounts of tissue.