Bioremediation of arsenic contamination from the environment: New approach to sustainable resource management

Present acceleration of Arsenic [As] exposure leads to severe health problems. Modern scientific approaches look towards potent bio-agents for the removal of such types of contaminations in sustainable ways. Microbes can potentially change the redox potential, solubility, pH by different complex reactions during bioremediation. There are many enzymes present in the microbial system which are involved in methylation such as As (V) reductase, monomethyl arsonic acid reductase, As (III) methyltransferase, and MMA (III) methyltransferase. On the other hand, microbes have As transformation ability and changed into different extractable forms with sulfide minerals such as arsenopyrite (FeAsS), enargite (Cu3AsS4) and realgar (As4S4). In some bacteria, the As-operon machinery thiol group bind with As, itdetoxifies its toxicity. Ars R gene and arsenic reductase enzyme (Ars C) play the key role in the reduction of As (V) to As (III) and detoxify by being transported outside of the cell by Ars AB As chemiosmotic efflux system. In fungi, As (V) is reduced to As (III) by the arsenate reductase and GSH glutathione converted into GSSH glutathione disulfide. In plants, As (III) conjugates with phytochelatin (PC) or GSH glutathione and accumulates in the vacuole or is converted into less toxic forms in the presence of arsenic reductase enzyme. This review focused on the potentiality and mechanisms of different microbes for As-detoxification in a sustainable manner.

Ovothiol-A Isolated from Sea Urchin Eggs Suppress Oxidative Stress, Inflammation, and Dyslipidemia Resulted in Restoration of Liver Activity in Cholestatic Rats

Cholestasis is dropping in bile flow, leading to the intrahepatic bulk of bile acids and other poisonous compounds with the progression of liver pathology, including hepatocellular injury and fibrosis. Ovothiols extracted from sea urchin display unusual antioxidant properties due to the peculiar position of the thiol group on the imidazole ring of histidine. The present study aims to evaluate the anti-fibrotic effect of Ovothiol-A in rats. 28 rats were allocated randomly into 4 groups: Sham, BDL, and BDL + Ovothiol A (500 mg/kg). All rats were treated for 7 days. Oxidative stress biomarkers, liver functions, lipid profile, and histology were all examined. The results revealed that BDL operation induced oxidative stress in rats, which negatively impacted liver functions, as confirmed by the histopathological examination. Ovothiol-A has been shown to lower oxidative stress and enhance lipid profile, resulting in considerable improvements in most biochemical markers. Also, histopathological examination showed an improvement in the liver architecture of the treated group compared to the BDL group. Ovothiol-A protects the liver against toxicity results from cholestasis in rats.

Precision synthesis of reducing-end thiol-modified cellulose enabled by enzyme selection

Enzyme-catalyzed iterative β-1,4-glycosylation of β-glycosides is promising for bottom-up polymerization of reducing-end-modified cello-oligosaccharide chains. Self-assembly of the chains from solution yields crystalline nanocellulose materials with properties that are tunable by the glycoside group used. Cellulose chains with a reducing-end thiol group are of interest to install a controllable pattern of site-selective modifications into the nanocellulose material. Selection of the polymerizing enzyme (cellodextrin phosphorylase; CdP) was pursued here to enhance the synthetic precision of β-1-thio-glucose conversion to generate pure “1-thio-cellulose” (≥95%) unencumbered by plain (unlabeled) cellulose resulting from enzymatic side reactions. The CdP from Clostridium stercorarium (CsCdP) was 21 times more active on β-1-thio-glucose (0.17 U/mg; 45 °C) than the CdP from Clostridium cellulosi (CcCdP), and it lacked hydrolase activity, which is substantial in CcCdP, against the α-d-glucose 1-phosphate donor substrate. The combination of these enzyme properties indicated that CsCdP is a practical catalyst for 1-thio-cellulose synthesis directly from β-1-thio-glucose (8 h; 25 mol% yield) that does not require a second enzyme (cellobiose phosphorylase), which was essential when using the less selective CcCdP. The 1-thio-cellulose chains had an average degree of polymerization of ∼10 and were assembled into highly crystalline cellulose II crystallinity material.

Magnetically induced self-assembly DNAzyme electrochemical biosensor based on gold-modified α-Fe2O3/Fe3O4 heterogeneous nanoparticles for sensitive detection of Ni2+

A magnetically induced self-assembly DNAzyme electrochemical biosensor based on gold-modified α-Fe2O3/Fe3O4 heterogeneous nanoparticles was successfully fabricated to detect Nickel(II) (Ni2+). The phase composition and magnetic properties of α-Fe2O3/Fe3O4 heterogeneous nanoparticles controllably prepared by the citric acid (CA) sol-gel method were investigated in detail. The α-Fe2O3/Fe3O4 heterogeneous nanoparticles were modified by using trisodium citrate as reducing agent, and the magnetically induced self-assembly α-Fe2O3/Fe3O4-Au nanocomposites were obtained. The designed Ni2+-dependent DNAzyme consisted of the catalytic chain modified with the thiol group (S1-SH) and the substrate chain modified with methylene blue (S2-MB). The MGCE/α-Fe2O3/Fe3O4-Au/S1/BSA/S2 electrochemical sensing platform was constructed and differential pulse voltammetry (DPV) was applied for electrochemical detection. Under the optimum experimental parameters, the detection range of the biosensor was 100 pM-10 µM (R2= 0.9978) with the limit of detection (LOD) of 55 pM. The biosensor had high selectivity, acceptable stability, and reproducibility (RSD = 4.03%).

Cellular effects of gliotoxin: Evaluation of a proteomic, isotope-based method to detect reactive cysteines

<p>Cysteinyl residues in proteins are important for many cellular processes and unregulated modification of the cysteine thiol group can have negative effects on cell vitality and viability. In this thesis, the potential for use of the isotope coded affinity tag (ICAT) method for detection of cysteine modification has been investigated. ICAT reagents label free cysteine thiols. The aim of this study was to use HL-60 cells treated with gliotoxin, a fungal metabolite with a reactive disulfide bridge, as a system to evaluate the performance of ICAT for identification of cysteine modification in a whole cell proteome. Gliotoxin has antimicrobial, antitumor, immunosuppressive and cytotoxic properties that have been related to cysteine modification in proteins. Cellular assays including viability using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, cell cycle analysis, and measurement of reactive oxygen species using dichlorofluorescin diacetate were used to establish conditions for measuring the effects of gliotoxin on HL-60 cells prior to large-scale cellular damage. Cells exposed to gliotoxin and control cells were then labeled with ICAT reagents and analysed by offline reversed phase liquid chromatography followed by matrix-assisted laser desorption/ionization tandem mass spectrometry. The pilot results identified tubulin, glyceraldehyde-3-phosphate dehydrogenase and peptidyl-prolyl cis-trans isomerase as putative targets of gliotoxin. Additionally, this study showed that ICAT can be used to detect modified cysteines from a highly complex sample, but further optimization is needed to unlock the full potential for detection of cysteine modification in complex samples.</p>

Cellular effects of gliotoxin: Evaluation of a proteomic, isotope-based method to detect reactive cysteines

<p>Cysteinyl residues in proteins are important for many cellular processes and unregulated modification of the cysteine thiol group can have negative effects on cell vitality and viability. In this thesis, the potential for use of the isotope coded affinity tag (ICAT) method for detection of cysteine modification has been investigated. ICAT reagents label free cysteine thiols. The aim of this study was to use HL-60 cells treated with gliotoxin, a fungal metabolite with a reactive disulfide bridge, as a system to evaluate the performance of ICAT for identification of cysteine modification in a whole cell proteome. Gliotoxin has antimicrobial, antitumor, immunosuppressive and cytotoxic properties that have been related to cysteine modification in proteins. Cellular assays including viability using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, cell cycle analysis, and measurement of reactive oxygen species using dichlorofluorescin diacetate were used to establish conditions for measuring the effects of gliotoxin on HL-60 cells prior to large-scale cellular damage. Cells exposed to gliotoxin and control cells were then labeled with ICAT reagents and analysed by offline reversed phase liquid chromatography followed by matrix-assisted laser desorption/ionization tandem mass spectrometry. The pilot results identified tubulin, glyceraldehyde-3-phosphate dehydrogenase and peptidyl-prolyl cis-trans isomerase as putative targets of gliotoxin. Additionally, this study showed that ICAT can be used to detect modified cysteines from a highly complex sample, but further optimization is needed to unlock the full potential for detection of cysteine modification in complex samples.</p>

Profiling the Concentration of Reduced and Oxidized Glutathione in Rat Brain Using HPLC/DAD Chromatographic System

This study aimed to develop a HPLC/DAD method in order to determine and quantify the reduced glutathione (GSH) and oxidized glutathione (GSSG) levels in rat brain. Due to the presence of the thiol group (-SH), GSH can interact with the Ellman's reagent (DTNB), with which it forms a reaction product through which the level of GSH can be quantified, using the DAD detection system. Chromatographic separation was achieved after a derivatization process by using a mobile phase acetonitrile (A) and phosphate buffer (20 mM, pH = 2.5) (B). The compounds of interest were detected at 330 nm using a chromatographic C8 column. The method of determination met the validation criteria, specified by the regulatory bodies. The applicability of the method was demonstrated in a chronic toxicology study of central nervous system (CNS), following different treatment regimens with haloperidol.

3C Based DNA Hybridization Method for Chromosomal Translocation Screening

Background: DNA probes have been widely used as diagnostic tools for chromosomal translocations in malignancies. PCR-based methods often fail to detect translocations such as MYC/TRD in chronic lymphocytic leukemia. In addition, microscopic techniques cannot be helpful due to size detection limitations. This study sought to design a screening tool using immobilized ssDNA probes on a nitrocellulose membrane followed by 3C library fragments hybridization. Results: Hence, we focused on developing a suitable 27 bp specific probe for the juxtaposed region of MYC and TRD. Colloidal gold nanoparticles (AuNP) functionalized translocation fragments of the MYC gene with a thiol group (MYC-AuNP-probe). Then TRD-probes were immobilized on nitrocellulose surface to detect TRD/MYC translocation in the SKW3 cells. Hybridization between DNA probes and 3C-library fragments of SKW3 cells was determined by color intensity. Optimal hybridization of the 3C library sample of the cell line to TRD-probe and MYC-AuNP-probe showed higher color intensity due to their convenient proximity to the juxtaposed region compared with normal cells. Conclusions: Our results demonstrated that DNA hybridization colorimetric assay could be a helpful technique in chromosomal rearrangements screening. Accordingly, the combination of 3C based techniques and DNA-DNA hybridization can identify cancer cells with high specificity and sensitivity.

The Antioxidant Properties and Biological Quality of Radish Seedlings Biofortified with Iodine

Iodine is an essential trace element for humans, and iodine deficiency is a significant health problem. In this study, an improved method for iodine biofortification based on seed germination was established. Solutions of KI (0.15, 0.30, 0.75 and 1.5 mg∙g−1 of seeds) were applied to germinating radish seeds of two cultivars Raphanus sativus L. var. sativus: Warta and Zlata. Compared with the control (seeds treated with water) the iodine content (in the radish sprouts produced by germinating seeds treated with KI were approximately 112.9–2730 times higher. The application KI rates did not adversely affect the biological quality of the radish sprouts. Regarding the biological quality of the iodine-enriched seedlings, we determined their length, dry mater, protein, soluble sugars, chlorophylls, total phenol, ascorbic acid, thiol group content and total antioxidant capacity. The effect of potassium iodide on the selected parameters of their biological quality varied depending on the KI doses and radish cultivars. The results showed that the most appropriate biofortification application rates were 0.15 and 0.30 mg KI per g seeds, because the enriched seedlings had excellent biological quality parameters.