Molecular cloning, characterization of copper/zinc superoxide dismutase and expression analysis of stress-responsive genes from Eisenia fetida against dietary zinc oxide

Metal binding feature of copper‒induced metallothionein from freshwater crab Sinopotamon henanense reveals its Cu‒thionein character

Sinopotamon Henanense expresses two metal‒induced metallothioneins (MTs), Cd‒induced MT and Cu‒induced MT (ShCuMT). The Cd‒induced MT has been characterized as a Cd‒thiolate MT. However, it is unknown whether ShCuMT is a Cu‒thiolate MT. In the present study, ShCuMT was expressed heterologously in Escherichia coli and purified by Ni‒NTA column and superdex‒75 column. And its metal‒binding feature was evaluated by DTNB reaction, circular dichroism spectroscopy (CD), isothermal microtitration (ITC), electrospray flight mass spectrometry (ESI‒TOF‒MS), and matrix‒assisted laser desorption ionization flight mass spectrometry (MALDI‒TOF‒MS). Bioinformatics analysis demonstrated that ShCuMT possessed the cysteine‒triplet motif of a Cu‒specific MT. Expression and purification of ShCuMT illustrated that SUMO tag used as the production system for ShCuMT resulted in a high production yield. The stability order of ShCuMT binding metal ions were Cu (Ⅰ) > Cd (Ⅱ) > Zn (Ⅱ). The CD spectrum indicated that ShCuMT binding with Cu (I) exhibited a compact thiol metal clusters structure. Besides, there emerged no a visible nickel‒thiol absorption after Ni‒NTA column affinity chromatography. The ITC results implied that Cu‒ShCuMT possessed the optimal thermodynamic conformation and the highest stoichiometric number of Cu (Ⅰ). Overall, the results suggested that SUMO fusion system is a robust and inexpensive approach for ShCuMT expression and Ni‒NTA column had no influence on metal binding of ShCuMT and Cu(Ⅰ) was considered its cognate metal ion, and ShCuMT possessed canonical Cu‒thiolate characteristics. The metal binding feature of ShCuMT reported here contributes to elucidating the structure‒function relationship of ShCuMT in S. Henanense.

Effects of soybean oil exposure on the survival, reproduction, biochemical responses, and gut microbiome of the earthworm Eisenia fetida

With increasing production of kitchen waste, cooking oil gradually enters the soil, where it can negatively affect soil fauna. In this study, we explored the effects of soybean oil on the survival, growth, reproduction, tissue structure, biochemical responses, mRNA expression, and gut microbiome of earthworms (Eisenia fetida). The median lethal concentration of soybean oil was found to be 15.59%. Earthworm growth and reproduction were significantly inhibited following exposure to a sublethal concentration of soybean oil (1/3 LC50, 5.2%). The activity of the antioxidant enzymes total superoxide dismutase (T-SOD), peroxidase (POD), and catalase (CAT) were affected under soybean oil exposure. The glutathione (GSH) content decreased significantly, whereas that of the lipid peroxide malondialdehyde (MDA) increased significantly after soybean oil exposure. mRNA expression levels of the SOD, metallothionein (MT), lysenin and lysozyme were significantly upregulated. The abundance of Bacteroides species, which are related to mineral oil repair, and Muribaculaceae species, which are related to immune regulation, increased within the earthworm intestine. These results indicate that soybean oil waste is toxic to earthworms. Thus, earthworms deployed defense mechanisms involving antioxidant system and gut microbiota for protection against soybean oil exposure-induced stress.

A critical review of the environmental impacts of manufactured nano-objects on earthworm species

The presence of manufactured nano-objects (MNOs) in various consumer or their (future large-scale) use as nanoagrochemical have increased with the rapid development of nanotechnology and therefore, concerns associated with its possible ecotoxicological effects are also arising. MNOs are releasing along the product life cycle, consequently accumulating in soils and other environmental matrices, and potentially leading to adverse effects on soil biota and their associated processes. Earthworms, of the group of Oligochaetes, are an ecologically significant group of organisms and play an important role in soil remediation, as well as acting as a potential vector for trophic transfer of MNOs through the food chain. This review presents a comprehensive and critical overview of toxic effects of MNOs on earthworms in soil system. We reviewed pathways of MNOs in agriculture soil environment with its expected production, release, and bioaccumulation. Furthermore, we thoroughly examined scientific literature from last ten years and critically evaluated the potential ecotoxicity of 16 different metal oxide or carbon-based MNO types. Various adverse effects on the different earthworm life stages have been reported, including reduction in growth rate, changes in biochemical and molecular markers, reproduction and survival rate. Importantly, this literature review reveals the scarcity of long-term toxicological data needed to actually characterize MNOs risks, as well as an understanding of mechanisms causing toxicity to earthworm species. This review sheds light on this knowledge gap as investigating bio-nano interplay in soil environment improves our major understanding for safer applications of MNOs in the agriculture environment.

Zinc-enriched probiotics enhanced growth performance, antioxidant status, immune function, gene expression, and morphological characteristics of Wistar rats raised under high ambient temperature

The present study was conducted to evaluate the effects of zinc-enriched probiotics (ZnP) on growth performance, antioxidant status, immune function, related gene expression, and morphological characteristics of Wistar rats raised under high heat stress condition during summer. 36, 6-week-old male Wistar rats were randomly divided into three groups; fed with basal diet (control), basal diet with probiotics (P), and basal diet with zinc-enriched probiotics supplementation (ZnP, 100 mg/L), for 40 consecutive days. Blood samples were collected through intracardiac method on the last day of experiment and tissues were collected from liver, heart, and kidneys. The results revealed that both P and ZnP significantly (P < 0.05) enhanced growth performance. However, ZnP remarkably increased glutathione content, glutathione peroxidase, and superoxide dismutase activities but reduced malondialdehyde level in serum of the Wistar rats. The concentration of IL-2, IL-6, and IFN-γ was significantly (P < 0.05) increased with treatments of P and ZnP compared to control group while IL-10 was significantly (P < 0.05) decreased. Additionally, the expression of SOD1, SOD2, MT1, and MT2 genes was significantly (P < 0.05) up-regulated with the treatment of ZnP, but Hsp90 and Hsp70 heat shock genes were significantly (P < 0.05) down-regulated with the treatment of P and ZnP, respectively. Hematoxylin and Eosin staining showed that both P and ZnP supplementation treatments induced changes in villus height and intestinal wall thickness. In conclusion, zinc-enriched probiotics supplementation can improve the growth performance of Wistar rats under high ambient temperature through enhancing antioxidant status, immune function, related genes expression, and intestinal morphological characteristics. This product may serves as a potential nutritive supplement for Wistar rats under high heat stress conditions.

Stress-responsive genes (hsp70 and mt) and genotoxicity elicited by roxarsone exposure in Carassius auratus

In this study, comet assay (single-cell gel electrophoresis), real-time quantitative PCR (qPCR) and proteomics approach were used to comprehensively assess toxicity elicited by roxarsone exposure in C. auratus at 50, 150 and 300 μg/L for 7, 14 and 21 days. Results of comet assay showed that DNA were seriously damaged under the pressure of roxarsone, especially the concentration of 50 μg/L that always maintained a sustained and increased damage effect to fish liver cell during the 21 days experiment. The expressions of biomarker genes showed that hsp70 gene expressions raised significantly and the group of 50 μg/L also showed a continued increased response effect, whereas mt gene was only slightly increased. Results of proteomics for the concentration of 300 μg/L found that thirty six significantly changed proteins were identified by MALDI-TOF/TOF-MS. They are involved in many important processes including energy producing, cytoskeleton stabilization, substance metabolism and stress response. Among these metabolites, carbohydrate metabolism (mainly occurred during day 1-14) and cytoskeleton proteins (mainly occurred during day 14-21) were the most identified proteins. These results revealed that the low levels of 50 μg/L probably led to a continuous damage than the higher groups during the experiment time. Furthermore, proteomics results might implied that though cell system expected to mobilize almost all the functional proteins to quickly establish a new homeostasis together when facing the roxarsone at first, but in the end the destroyed cell cytoskeleton structure might burst the bubble.

Copper-zinc-superoxide dismutase (CuZnSOD), an antioxidant gene from seahorse (Hippocampus abdominalis); molecular cloning, sequence characterization, antioxidant activity and potential peroxidation function of its recombinant protein

Copper-zinc-superoxide dismutase (CuZnSOD) from Hippocampus abdominalis (HaCuZnSOD) is a metalloenzyme which belongs to the ubiquitous family of SODs. Here, we determined the characteristic structural features of HaCuZnSOD, analyzed its evolutionary relationships, and identified its potential immune responses and biological functions in relation to antioxidant defense mechanisms in the seahorse. The gene had a 5' untranslated region (UTR) of 67 bp, a coding sequence of 465 bp and a 3' UTR of 313 bp. The putative peptide consists of 154 amino acids. HaCuZnSOD had a predicted molecular mass of 15.94 kDa and a theoretical pI value of 5.73, which is favorable for copper binding activity. In silico analysis revealed that HaCuZnSOD had a prominent Cu-Zn_superoxide_dismutase domain, two Cu/Zn signature sequences, a putative N-glycosylation site, and several active sites including Cu(2+) and Zn(2+) binding sites. The three dimensional structure indicated a β-sheet barrel with 8 β-sheets and two short α-helical regions. Multiple alignment analyses revealed many conserved regions and active sites among its orthologs. The highest amino acid identity to HaCuZnSOD was found in Siniperca chuatsi (87.4%), while Maylandia zebra shared a close relationship in the phylogenetic analysis. Functional assays were performed to assess the antioxidant, biophysical and biochemical properties of overexpressed recombinant (r) HaCuZnSOD. A xanthine/XOD assay gave optimum results at pH 9 and 25 °C indicating these may be the best conditions for its antioxidant action in the seahorse. An MTT assay and flow cytometry confirmed that rHaCuZnSOD showed peroxidase activity in the presence of HCO3(-). In all the functional assays, the level of antioxidant activity of rHaCuZnSOD was concentration dependent; metal ion supplementation also increased its activity. The highest mRNA expressional level of HaCuZnSOD was found in blood. Temporal assessment under pathological stress showed a delay response by HaCuZnSOD. Our findings demonstrated that HaCuZnSOD is an important antioxidant, which might be involved in the host antioxidant defense mechanism against oxidative stress.

Antioxidant responses of Annelids, Brassicaceae and Fabaceae to pollutants: a review

Pollutants, such as Metal Trace Elements (MTEs) and organic compounds (polycyclic aromatic hydrocarbons, pesticides), can impact DNA structure of living organisms and thus generate damage. For instance, cadmium is a well-known genotoxic and mechanisms explaining its clastogenicity are mainly indirect: inhibition of DNA repair mechanisms and/or induction of Reactive Oxygen Species (ROS). Animal or vegetal cells use antioxidant defense systems to protect themselves against ROS produced during oxidative stress. Because tolerance of organisms depends, at least partially, on their ability to cope with ROS, the mechanisms of production and management of ROS were investigated a lot in Ecotoxicology as markers of biotic and abiotic stress. This was mainly done through the measurement of enzyme activities The present Review focuses on 3 test species living in close contact with soil that are often used in soil ecotoxicology: the worm Eisenia fetida, and two plant species, Trifolium repens (white clover) and Brassica oleracea (cabbage). E. fetida is a soil-dwelling organism commonly used for biomonitoring. T. repens is a symbiotic plant species which forms root nodule with soil bacteria, while B. oleracea is a non-symbiotic plant. In literature, some oxidative stress enzyme activities have already been measured in those species but such analyses do not allow distinction between individual enzyme involvements in oxidative stress. Gene expression studies would allow this distinction at the transcriptomic level. A literature review and a data search in molecular database were carried out on the basis of keywords in Scopus, in PubMed and in Genbank™ for each species. Molecular data regarding E. fetida were already available in databases, but a lack of data regarding oxidative stress related genes was observed for T. repens and B. oleracea. By exploiting the conservation observed between species and using molecular biology techniques, we partially cloned missing candidates involved in oxidative stress and in metal detoxification in E. fetida, T. repens and B. oleracea.

Ecotoxicological effects of a veterinary food additive, copper sulphate, on antioxidant enzymes and mRNA expression in earthworms

The present study was aimed to investigate the effect of the veterinary food additive copper sulphate (CuSO₄) on the eco-toxicological responses of earthworms Eisenia fetida (E. fetida). The following biomarkers were measured: catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione-S-transferase (GST) activities. Gene expression analyses such as metallothionein (MT) and heat shock protein 70 (Hsp70) were also examined. A time-dependent increase of CAT activity was found at 400 mg/kg and SOD activity at 200 and 400 mg/kg. The highest expression of Hsp70 (4.4-fold) was observed at day 15 at 400 mg/kg. Our results indicated that the measured antioxidant enzymes (except GST) had the ability to provide antioxidant defenses against the stressor; and compared to expression of MT, expression of Hsp70 could be more reliable molecular tools with predictive possibilities to monitor the eco-toxicity of stressors such as feed additive CuSO₄.

Molecular cloning, characterization of CAT, and eco-toxicological effects of dietary zinc oxide on antioxidant enzymes in Eisenia fetida

The full-length cDNA of catalase (EfCAT) from Eisenia fetida was cloned (GenBank accession no. JN617999). Sequence characterization revealed that EfCAT protein sequence contained proximal heme-ligand signature sequence ((351)RLFSYSDTH(359)), two glycosylation sites (N(145) and N(436)), the proximal active site signature ((61)FDRERIPERVVHAKGAGA(78)), and 12 amino acids (N(145), H(191), F(195), S(198), R(200), N(210), Y(212), K(234), I(299), W(300), Q(302), and Y(355)), which were identified as putative residues involved in NADPH binding. These conserved motifs and catalase signature sequences were essential for the structure and function of EfCAT. The present study also investigated the effect of the veterinary food additive zinc oxide on antioxidant processes in E. fetida, at different concentrations and exposure durations. A significant increase (by 106.0 % compared to controls) in CAT activity at 500 mg/kg was registered at day 15. The superoxide dismutase (SOD) activity at 500 mg/kg increased to the maximum value (by 44.0 %) measured at day 15. There was a significant increase in glutathione peroxidase (GPx) activity for all concentrations after 5 days. The results showed that dietary Zn (500 mg/kg) causes oxidative damage to earthworms. At early stages of earthworms exposed to ZnO, GPx is the main enzyme to impair the oxidative status; while at later stages the enzymes CAT and SOD were the main indicators of oxidative stress. The antioxidant enzymatic variations may be an adaptive response of earthworms to survive in contaminated soils.

Baculovirus replication induces the expression of heat shock proteins in vivo and in vitro

A recent handful of studies have linked baculovirus infection with the induction of heat shock proteins, a highly conserved family of cytoprotective proteins. Here, we demonstrate baculovirus-stimulated upregulation of hsp70 transcription in the natural host, Helicoverpa zea. Larvae lethally infected with Helicoverpa zea single nucleopolyhedrovirus (HzSNPV) accumulated hsp70 transcripts throughout the 72-hour course of infection in the midgut, hemocytes, and fat body. While a maximal 17- or 15-fold induction of hsp70 was noted in the midgut and hemocytes, respectively, by 72 hours postinfection, the level of hsp70 transcription in the fat body of larvae was greater than two orders of magnitude higher than in mock-infected larvae. These results were largely mirrored in cultures of infected cells, and a potentiation effect was observed in cells that were both heat shocked and infected. In contrast, Spodoptera frugiperda multiple nucleopolyhedrovirus and ultraviolet-inactivated HzSNPV did not stimulate hsp70 transcription in these non-permissive larvae and in cell culture, respectively. Taken together, this report documents baculovirus-mediated upregulation of hsp70 in the host and demonstrates the requirement for productive infection for hsp70 induction in vitro and in vivo.

Characterization and expression of superoxide dismutase genes in Chironomus riparius (Diptera, Chironomidae) larvae as a potential biomarker of ecotoxicity

Superoxide dismutase (SOD, EC 1.15.1.1) is an enzyme involved in the scavenging of reactive oxygen species (ROS) into molecular oxygen and hydrogen peroxide. In this study, a copper-zinc superoxide dismutase (Cu-ZnSOD) gene and a manganese superoxide dismutase (MnSOD) gene in aquatic midge, Chironomus riparius (CrSODs) was identified using an Expressed Sequence Tag (EST) database generated by 454 pyrosequencing. A multiple sequence alignment of C. riparius sequences revealed high homology with other insect sequences in terms of the amino acid level. Phylogenetic analysis of the CrSODs revealed that they were grouped with SODs of other organisms, such as Polypedilum vanderplanki, Drosophila melanogaster, Aedes aegypti, Anopheles gambiae, Culex quinquefasciatus and Bombyx mori. Expression of the corresponding CrSODs was analyzed during different developmental stages and following exposure to various environmental contaminants with different mode of actions i.e., paraquat, cadmium, benzo[a]pyrene, and chloropyrifos. CrSOD gene expression was significantly up or down regulated in response to exposure to the chemicals tested. The overall results suggested that SOD gene expression provided a platform for the understanding of oxidative stress responses caused by exposure to various environmental contaminants, and the SOD genes could be used as biomarkers for environmental disturbances such as oxidative stress initiated by xenobiotics.