Characteristics of trapping copper ions with scrolled ferritin reactor in the flowing seawater

Unraveling potential mechanism of different metal ions effect on anammox through big data analysis, molecular docking and molecular dynamics simulation

Heavy metals (HMs) have been widely reported to pose an adverse effect on anaerobic ammonia oxidation (anammox) bacteria, yet the underlying mechanisms remain unclear. This study provides new insights into the potential mechanisms of interaction between HMs and functional enzymes through big date analysis, molecular docking and molecular dynamics simulation. The statistical analysis indicated that 10 mg/L Cu(II) and Cd(II) reduced nitrogen removal rate (NRR) by 85% and 43%, while 5 mg/L Fe(II) enhanced NRR by 29%. Additionally, the results of molecular simulations provided a microscopic interpretation for these macroscopic data. Molecular docking revealed that Hg(II) formed a distinctive binding site on ferritin, while other HMs resided at iron oxidation sites. Furthermore, HMs exhibited distinct binding sites on hydrazine dehydrogenase. Concurrently, the molecular dynamics simulation results further substantiated their capacity to form complexes. Cu(II) displayed the strongest binding affinity with ferritin for -1576 ± 79 kJ/mol in binding free energy calculation. Moreover, Cd(II) bound to ferritin and HDH for -1052.67 ± 58.49 kJ/mol, -290.02 ± 49.68 kJ/mol, respectively. This research addressed a crucial knowledge gap, shedding light on potential applications for remediating heavy metal-laden industrial wastewater.

Chronic Microplastic Exposure and Cadmium Accumulation in Blue Crabs

Aquatic ecosystems are severely threatened by the presence of a multitude of pollutants. In seas and oceans, the amount of plastics continues to increase and there is great concern about toxic element accumulation. Specifically, cadmium (Cd), a toxic metal, is highly relevant to public health safety due to its ability to accumulate in the internal tissues of crustaceans; likewise, microplastics (MPs) are emerging as pollutants capable of causing alterations in marine organisms. The aim of this study was thus to evaluate the accumulation and distribution of Cd in the tissue of blue crabs (Callinectes sapidus) chronically exposed to MPs (25 μg L^-1). In total, 24 crabs were exposed in water for 118 days to 2 types of MPs (virgin and oxidised). During the final 21 days of the experiment, the crabs were fed with tuna liver, a viscera in which Cd accumulates (mean of 7.262 µg g^-1). The presence of MPs caused no changes in Cd concentrations in either the haemolymph or tissues (hepatopancreas, gills, and muscles) of the crabs, although for oxidised MPs, there was a positive correlation between Cd concentrations in the hepatopancreas and muscles, a relevant finding for food safety.

miR-122 promotes hepatic antioxidant defense of genetically improved farmed tilapia (GIFT, Oreochromis niloticus) exposed to cadmium by directly targeting a metallothionein gene

MicroRNAs (miRNAs) are small, non-coding RNAs that regulate target gene expression by binding to the 3'untranslated region (3'UTR) of the target mRNA. MiRNAs regulate a large variety of genes, including those involved in liver homeostasis and energy metabolism. Down-regulated levels of hepatic miR-122 were found in genetically improved farmed tilapia (GIFT, Oreochromis niloticus) exposed to cadmium (Cd) stress. Here, we report for the first time that reduction of miR-122 post-transcriptionally increased metallothionein (MT) mRNA levels by binding to its 3'UTR, as shown by a 3' UTR luciferase reporter assay. The expression levels of miR-122 were negatively related to MT levels in GIFT under Cd stress. We performed in vivo functional analysis of miR-122 by injecting the fish with a miR-122 antagomir. Inhibition of miR-122 levels in GIFT liver caused a significant increase in MT expression, affected white blood cell and red blood cell counts, and serum alanine and aspartate aminotransferase activities, and glucose levels, all of which may help to relieve Cd stress-related liver stress. miR-122 silencing modulated oxidative stress and stimulated the activity of antioxidant enzymes. Our findings indicate that miR-122 regulated MT levels by binding to the 3'UTR of MT mRNA, and this interaction affected Cd stress induction and the resistance response in GIFT. We concluded that miR-122 plays an important role in regulating the stress response in GIFT liver. Our findings may contribute to understanding the mechanisms of miRNA-mediated gene regulation in tilapia in response to environmental stresses.

Removal of cadmium by combining deferasirox and desferrioxamine chelators in rats

An investigation was conducted to evaluate the ability of two chelators, deferasirox and desferrioxamine (DFO), in removing cadmium from biological system. The potential efficiency of those chelators were investigated after cadmium administration for 60 days following two dose levels of 20 and 40 mg/kg body weight daily to male rats. However, abnormalities were observed in clinical signs after cadmium administration, such as yellowish discoloration of hair, flaccid and hypotonic muscles, irritability, weakness and loss of weight. The hypothesis that the two chelators might be more efficient as combined therapy than single therapy in removing metal ions from the body was considered. In this way, two known chelators, deferasirox and DFO were chosen and tested in the acute rat model. The chelation therapy results show that deferasirox and DFO are able ?to remove cadmium ions from the body, while iron concentration returned to the normal level and symptoms are decreased.

Superoxide dismutase, catalase and acetylcholinesterase: biomarkers for the joint effects of cadmium, zinc and methyl parathion contamination in water

Heavy metals are known to reduce the activities of antioxidant enzymes (e.g. superoxide dismutase, catalase), while organophosphorous insecticides are known to inhibit the activity of the enzyme acetylcholinesterase. In this study, the activities of these three enzymes in zebrafish (Danio rerio) tissues were assessed to evaluate the consequences heavy metal and organophosphate contamination in aquatic systems. When the fish were contacted with water containing a single pollutant, superoxide dismutase activity was affected by the presence of Cd but not by methyl parathion or Zn. However, catalase and acetylcholinesterase activities were sensitive to all three pollutants. The combined treatment showed that the three enzymes could be chosen as biomarkers of joint pollution by both metals and organophosphate. Toxicity tests showed an antagonism interaction between methyl parathion and Cd or Zn, and the change of enzyme activities at 96 hours was in accordance with that.

Chelation of cadmium by combining deferasirox and deferiprone in rats

The present research aimed to characterize the potential efficiency of two chelators after cadmium administration for 60 days following two dose levels of 20 and 40 mg/kg body weight daily to male rats. However, the hypothesis that the two chelators might be more efficient as combined therapy than as single therapy in removing cadmium from the body was considered. In this way, two known chelators deferasirox and deferiprone (L1) were chosen and tested in the acute rat model. Two chelators were given orally as a single or combined therapy for the period of a week. Cadmium and iron concentrations in various tissues were determined by graphite furnace and flame atomic absorption spectrometry methods, respectively. The combined chelation therapy results show that Deferasirox and L1 are able to remove cadmium ions from the body while iron concentration returned to the normal level and symptoms are also decreased.

Proteomic changes in response to acute cadmium toxicity in gill tissue of Paralichthys olivaceus

In the present study, we developed a two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) technique for examining the response of the proteome from gill tissue of Paralichthys olivaceus (POGT) to acute cadmium (AC) toxicity. Approximately 700 protein spots were detected from the gill sample when applying a 600μg protein 2D-PAGE gel in the pH range 5.0-8.0, and approximately 400 of these were identified by peptide mass fingerprinting (PMF) and database search. Compared to a control sample, significant changes were visualized in 18 protein spots exposed to seawater cadmium acute toxicity at 10.0ppm for 24h. Among these spots, two were up-regulated, one was down-regulated, seven showed low expression, and eight showed high expression. The collected spots were further identified by PMF and database search. Ten of the 18 proteins identified on the 2D-PAGE gel, including heat shock protein 70 and calcium-binding protein, demonstrated a synchronous response to AC, and we suggest that the variable levels and trends of these spots on the gel might be utilized as biomarker profiles to investigate cadmium contamination levels in seawater and to evaluate the degree of risk of human fatalities. The experimental results emphasize that the application of multiple biomarkers has an advantage over single biomarkers for monitoring levels of heavy metal contamination in seawater.

Apoferritin as a bionanomaterial to facilitate the electron transfer reactivity of hemoglobin and the catalytic activity towards hydrogen peroxide

In this report, apoferritin as a stable bionanomaterial was modified with hemoglobin on pyrolytic graphite electrode. Rapid electron transfer reactions of hemoglobin were achieved with the help of apoferritin in a large pH range. Moreover, hemoglobin as an enzyme exhibits fine electrocatalytic activity towards the reaction of hydrogen peroxide, and a wide concentration range of linear relationship between the reduction peak current and the concentration of hydrogen peroxide has been obtained with a higher upper detection limit, which may be further developed for a hydrogen peroxide biosensor. Therefore, a new property of apoferritin is explored, in which apoferritin works as a bionanomaterial to be an accelerant of the electron transfer of Hb and a stabilizer to retain the catalytic ability of the protein under mal-condition.

Cadmium affects the expression of metallothionein (MT) and glutathione peroxidase (GPX) mRNA in goldfish, Carassius auratus

Cadmium (Cd) is a widespread non-essential heavy metal that enters the aquatic environment as a result of natural and human-caused activities, including industrial effluent, mining, and agricultural runoff. In the present study, we investigated time and dose-related effect of CdCl(2) on metallothionein (MT) and glutathione peroxidase (GPX) mRNA levels in a number of goldfish tissues, in vivo. Basal MT and GPX mRNA levels remained unchanged in the tissues tested throughout the experiment. Injection with CdCl(2) significantly increased MT mRNA levels in the brain, liver, kidney and intestine in a dose-dependant manner at all time tested (6, 12, 24 and 36 h). We isolated the full length GPX cDNA from goldfish kidneys, and found it to contain 785 nucleotides, including an open reading frame, predicted to encode a protein of 142 amino acids. In contrast, injection with CdCl(2) significantly decreased GPX mRNA levels in the liver and kidney in a time-, and dose-, dependant, and became undetectable after 12, 24 and 36 h. The findings provide molecular characterization of MT and GPX in goldfish and suggest that exposure to Cd results in significant physiological changes in goldfish.

Characteristics of structure, composition, mass spectra, and iron release from the ferritin of shark liver (Sphyrna zygaena)

The ferritin consists of a protein shell constructed of 24 subunits and an iron core. The liver ferritin of Sphyrna zygaena (SZLF) purified by column chromatography is a protein composed of eight ferritins containing varying iron numbers ranging from 400+/-20 Fe3+/SZLF to 1890+/-20 Fe3+/SZLF within the protein shell. Nature SZLF (SZLFN) consisting of holoSZLF and SZLF with unsaturated iron (SZLFUI) to have been purified with polyacrylamide gel electrophoresis (PAGE) exhibited five ferritin bands with different pI values ranging from 4.0 to 7.0 in the gel slab of isoelectric focusing (IEF). HoloSZLF purified by PAGE (SZLFE) not only had 1890+/-20 Fe3+/SZLFE but also showed an identical size of iron core observed by transmission electron microscopy (TEM). Molecular weight of approximately 21 kDa for SZLFE subunit was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Four peaks of molecular ions at mass/charge (m/z) ratios of 10611.07, 21066.52, 41993.16, and 63555.64 that come from the SZLFE were determined by matrix-assisted laser desorption ionization/time-of-flight mass spectrometry (MALDI-TOF MS), which were identified as molecular ions of the ferritin subunit (M+) and its polymers, namely, [M]2+, [M]+, [2M]+, and [3M]+, respectively. Both SZLFE and a crude extract from shark liver of S. zygaena showed similar kinetic characteristics of complete iron release with biphasic behavior. In addition, a combined technique of visible spectrometry and column chromatography was used for studying ratio of phosphate to Fe3+ within the SZLFE core. Interestingly, this ratio maintained invariable even after the iron release, which differed from that of other mammal ferritins.