Physiological responses of low- and high-cadmium accumulating Robinia pseudoacacia-rhizobium symbioses to cadmium stress.

The role of rhizobia in alleviating cadmium (Cd) stress in woody legumes is still unclear. Therefore, two types of black locust (Robinia pseudoacacia L.) with high and low Cd accumulation abilities were selected from 11 genotypes in China, and the effects of rhizobium (Mesorhizobium huakuii GP1T11) inoculation on the growth, CO2 and H2O gas exchange parameters, Cd accumulation, and the absorption of mineral elements of the high (SX) and low Cd-accumulator (HB) were compared. The results showed that rhizobium-inoculation significantly increased biomass, shoot Cd contents, Cd accumulation, root-to-shoot translocation factor (TF) and the absorption and accumulation of mineral elements in both SX and HB. Rhizobium-inoculation increased chlorophyll a and carotenoid contents, and the intercellular carbon dioxide concentrations in HB plants. Under Cd exposure, the high-accumulator SX exhibited a significant decrease in photosynthetic CO2 fixation (Pn) and an enhanced accumulation of Cd in leaves, but coped with Cd exposure by increasing chlorophyll synthesis, regulating stomatal aperture (Gs), controlling transpiration (Tr), and increasing the absorption and accumulation of mineral elements. In contrast, the low-accumulator HB was more sensitive to Cd exposure despite preferential accumulation of Cd in roots, with decreased chlorophyll and carotenoid contents, but significantly increased root biomass. Compared to the low-accumulator HB, non-inoculated Cd-exposed SX plants had higher chlorophyll contents, and rhizobium-inoculated Cd-exposed SX plants had higher Pn, Tr, and Gs as well as higher levels of P, K, Fe, Ca, Zn, and Cu. In conclusion, the high- and low-Cd-accumulator exhibited different physiological responses to Cd exposure. Overall, rhizobium-inoculation of black locust promoted the growth and heavy metal absorption, providing an effective strategy for the phytoremediation of heavy metal-contaminated soils by this woody legume.

Spirulina platensis extract improves the production and defenses of the common bean grown in a heavy metals-contaminated saline soil.

Plants have to cope with several abiotic stresses, including salinity and heavy metals (HMs). Under these stresses, several extracts have been used as effective natural biostimulants, however, the use of Spirulina platensis (SP) extract (SPE) remains elusive. The effects of SPE were evaluated as soil addition (SA) and/or foliar spraying (FS) on antioxidant defenses and HMs content of common bean grown in saline soil contaminated with HMs. Individual (40 or 80 mg SPE/hill added as SA or 20 or 40 mg SPE/plant added as FS) or integrative (SA+FS) applications of SPE showed significant improvements in the following order: SA-80+FS-40 > SA-80+FS-20 > SA-40+FS-40 > SA-40+FS-20 > SA-80 > SA-40 > FS-40 > FS-20 > control. Therefore, the integrative SA+FS with 40 mg SP/plant was the most effective treatment in increasing plant growth and production, overcoming stress effects and minimizing contamination of the edible part. It significantly increased plant growth (74%-185%) and yield (107%-227%) by enhancing net photosynthetic rate (78.5%), stomatal conductance (104%), transpiration rate (124%), and contents of carotenoids (60.0%), chlorophylls (49%-51%), and NPK (271%-366%). These results were concurrent with the marked reductions in malondialdehyde (61.6%), hydrogen peroxide (42.2%), nickel (91%-94%), lead (80%-9%), and cadmium (74%-91%) contents due to the improved contents of glutathione (87.1%), ascorbate (37.0%), and α-tocopherol (77.2%), and the activities of catalase (18.1%), ascorbate peroxidase (18.3%), superoxide dismutase (192%), and glutathione reductase (52.2%) as reinforcing mechanisms. Therefore, this most effective treatment is recommended to mitigate the stress effects of salinity and HMs on common bean production while minimizing HMs in the edible part.

Co-exposure of sulfur nanoparticles and Cu alleviate Cu stress and toxicity to oilseed rape Brassica napus L.

Experiments were performed to explore the impact of sulfur nanoparticles (SNPs) on growth, Cu accumulation, and physiological and biochemical responses of oilseed rape (Brassica napus L.) inoculated with 5 mg/L Cu-amended MS medium supplemented with or without 300 mg/L SNPs exposure. Cu exerted severe phytotoxicity and inhibited plant growth. SNPs application enhanced the shoot height, root length, and dry weight of shoot and root by 34.6%, 282%, 41.7% and 37.1%, respectively, over Cu treatment alone, while the shoot and root Cu contents and Cu-induced lipid perodixation as the malondialdehyde (MDA) levels in shoots and roots were decreased by 37.6%, 35%, 28.4% and 26.8%. Further, the increases in superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR) and glutathione S-transferase (GST) enzyme activities caused by Cu stress were mitigated in shoots (10.9%-37.1%) and roots (14.6%-35.3%) with SNPs addition. SNPs also positively counteracted the negative effects on shoot K, Ca, P, Mg, Mn, Zn and Fe contents and root K, Ca, Mg and Mn contents from Cu exposure alone, and significantly promoted the nutrients accumulation in plant. Additionally, in comparison with common bulk sulfur particles (BSPs) and sulfate, SNPs showed more positive effects on promoting growth in shoots (6.7% and 19.5%) and roots (10.9% and 15.1%), as well as lowering the shoot Cu content (40.1% and 43.3%) under Cu stress. Thus, SNPs application has potential to be a green and sustainable technology for increasing plant productivity and reducing accumulation of toxic metals in heavy metal polluted soils.

Transcriptomics reveals the mechanism of selenium-enriched Lactobacillus plantarum alleviating brain oxidative stress under cadmium stress in Luciobarbus capito.

Cadmium (Cd) is one of toxic metal in environment and is thought to affect nervous system. There were an increasing number of studies on selenium (Se)-enriched probiotics which were believed to produce bioactive nanoselenium. The antagonism of Se on heavy metals can significantly affect biological toxicity of heavy metals. This study aimed to elucidate possible mechanism of brain injury in Luciobarbus capito after Cd exposure and the mitigation of Se-enriched probiotics through transcriptome analysis. The results revealed 465 differentially expressed genes in the Cd and the control brains (Cd vs C), including 320 genes with upregulated expression and 145 genes with downregulated expression. In addition, we found that there were 4117 differentially expressed genes in the Se-enriched L. plantarum plus Cd and the control brains (S1L1-Cd vs C), including 2552 genes with upregulated expression and 1565 genes with downregulated expression. There were 147 differentially expressed genes in the Se-enriched L. plantarum plus Cd and the control brains (S1L1-Cd vs Cd), including 40 genes with upregulated expression and 107 genes with downregulated expression. Moreover, GO enrichment analysis indicated that the differentially expressed genes were involved in biological processes cellular component, and molecular function. KEGG enrichment analysis indicated that MAPK signaling pathway, calcium signaling pathway, and PI3K-Akt signaling pathway were significantly enriched. Subsequently, qRT-PCR was performed, and we selected 15 related differentially expressed genes for verification. The qRT-PCR results revealed the same trend as the RNA-Seq results. In conclusion, this study elucidated relieving effect of Se-enriched probiotics on Cd exposure-induced brain oxidative stress. This study provided a theoretical basis for further research on genes related to Cd poisoning and the amelioration of Se-enriched probiotics on Cd poisoning.

Effects of polystyrene nanoplastics on lead toxicity in dandelion seedlings.

Increasing rates of commercialization and industrialization have led to the comprehensive evaluation of toxic effects of microplastics on crop plants. However, research on the impact of functionalized polystyrene nanoplastics on the toxicity of heavy metals remains limited. This study investigated the effects of polystyrene, carboxy-modified polystyrene, and amino-modified polystyrene on lead (Pb) toxicity in dandelion seedlings. The results showed that carboxy -modified polystyrene with a negative charge absorbed more Pb2+ than polystyrene and amino-modified polystyrene, and their maximum adsorption amounts were 5.328, 0.247, and 0.153 µg g-1, respectively. The hydroponic experiment demonstrated that single amino-modified polystyrene was more toxic to dandelion seedlings than polystyrene and carboxy-modified polystyrene. The presence of Pb2+ was found to increase antioxidant enzymes (superoxide dismutase and catalase) and non-antioxidant enzymes (glutathione and ascorbic acid) activities in response to excessive reactive oxygen species in dandelion leaves and roots treated with polystyrene and carboxy-modified polystyrene, while it did not change much when amino-modified polystyrene was added. Interestingly, compared with single Pb2+, the addition of amino-modified polystyrene with positive charges induced an obvious decrease in the above parameters; however, they declined slightly in the treatments with polystyrene and carboxy-modified polystyrene despite a stronger adsorption capacity for Pb2+. Similarly, the bioactive compounds, including flavonoids, polyphenols, and polysaccharides in dandelion, showed a scavenging effect on O2- and H2O2, thereby inhibiting the accumulation and reducing medicinal properties. This study found that the effects of microplastics on the uptake, distribution, and toxicity of heavy metals depended on the nanoparticle surface charge.

Phytoremediation potential of hybrids of the exotic plant Xanthium strumarium and its native congener Xanthium sibiricum for cadmium-contaminated soils.

Exotic plants could play an essential role in the restoration of heavy metal-contaminated soil. This study evaluated the tolerance of and extraction of cadmium (Cd) by ZCR (CR♀ × LT♂), hybrids of Xanthium strumarium (LT, exotic species) and X. sibiricum (CR, indigenous congener), and their parental species under different Cd treatments (0, 10, 40, and 80 mg·kg-1). The results showed that the hybrids had significantly improved tolerance to Cd. Under Cd stress, the biomass of ZCR increased by more than 50% on average compared with that of CR. Moreover, the hybrids showed a more remarkable ability to transport Cd from the root to the shoot. The Cd content of the shoots of ZCR increased by 128.33, 147.22, and 252.63% when treated with 10, 40, and 80 mg·kg-1 Cd, respectively. ZCR stored more than 70% of Cd in litter leaves, thereby reducing the toxic effects of Cd on photosynthesis and growth. The results showed that ZCR showed excellent Cd tolerance and enrichment in the presence of Cd. The hybrids of Xanthium strumarium and its native congener X. sibiricum may remediate soil Cd pollution.Novelty statementWith the changing world economy and increasing human activities, exotic plants have become a global issue of common concern to the international community. This study describes new findings on using hybrids of the exotic plant of Xanthium strumarium and its native congener Xanthium sibiricum for the restoration of cadmium-contaminated soils. Under Cd stress, the hybrids' biomass, tolerance, and ability to accumulate Cd were significantly higher than that of X. sibiricum, indicating that hybrids gained useful heavy metal extraction traits from X. strumarium.

Protecting Effects of N-acetyl Cysteine Supplementation Against Lead and Cadmium-Induced Brain Toxicity in Rat Models.

We aimed to investigate mitigating effects of N-acetylcysteine (NAC) on the oxidative stress, apoptosis and Parkinson's disease (PD)-related genes in the brain tissue of male rats exposed to continuous doses of cadmium and lead. Rats were randomly divided into five groups, including G1 (control), G2 (continuous dose of Cd), G3 (continuous dose of Pb), G4 (continuous dose of Cd + NAC), and G5 (continuous dose of Pb + NAC). Biomarkers of oxidative stress, malondialdehyde (MDA), and total antioxidant capacity (TAC) were measured. Expression of PD- and apoptosis-related genes was considered using RT-PCR. Chronic exposure to these heavy metals was associated with accumulation of Pb and Cd in the brain and blood and caused severe morphological changes in the brain, as well as decreased body and brain weights. Continuous exposure to Cd and Pb significantly decreased TAC content and SOD expression but increased MDA level in the brain tissues (P < 0.001). A significant increase was observed in expression of PD-related genes, Parkin, Pink1, LRRK2, SNCA, and Caspase-3 in the brain tissues following exposure to Cd and Pb. Pb exhibited stronger toxicity on the brain tissue compared to Cd. NAC supplementation not only improved morphological changes, but also compensated antioxidant capacity and expression of apoptosis- and PD-related genes in the brain tissues when compared to rats exposed to Pb and Cd alone. Chronic exposure to Pb and Cd is strongly associated with accumulation of these heavy metals in the brain, morphological changes, antioxidants depletion, oxidative stress, and brain cells apoptosis. Changes in expression of PD-related genes indicate the higher risk of PD among individuals who are chronically exposed to these heavy metals. NAC can protect brain tissue against Pb and Cd toxicity by elevating antioxidants capacity, mitigating oxidative stress, apoptosis, and down-regulating of PD-related genes.

Potential molecular and graphene oxide chelators to dissolve amyloid-ß plaques in Alzheimer's disease: a density functional theory study.

The onset of Alzheimer's disease (AD) is caused by amyloid-ß (Aß) aggregation. Elevated levels of metals, specifically copper, zinc, iron, and aluminum, accumulate in senile Aß; plaque deposits, disrupting normal brain homeostasis and cognitive functions. In this investigation, we studied the potential of several molecular and graphene oxide chelators to be used for future AD research and chelation therapy. To understand the interactions between selected metals (Cu, Zn, Fe, and Al), the Aß peptide, and various potential metal chelating compounds, we implemented the density functional theory (DFT) method to calculate the binding energies of each metal-molecule complex. The binding energy of each metal-chelator complex was compared with that of the metal-Aß compound to determine the chelation potential of the selected chelator. The potential chelating agents studied were 8-hydroxyquinoline-2-carboxaldehyde isonicotinoyl hydrazone (INNHQ), 8-hydroxyquinoline-2-carboxaldehyde 2-furoyl hydrazone (HQFUH), quercetin, and graphene oxide (GO). Our calculated binding energies revealed that the HQFUH molecule holds direct ability to chelate copper, zinc, iron, and aluminum. In addition, the GO complex with a 12.5% oxygen concentration demonstrates aluminum chelation ability. Our results demonstrate that HQFUH and GO can be used in future AD drug development research and therapy to target toxic metal-Aß interactions and reduce Aß aggregation.

Broad-spectrum treatment of bacterial biofilms using magneto-responsive liquid metal particles.

The formation and proliferation of bacterial biofilms on surfaces, particularly those on biomedical devices, is a significant issue that results in substantial economic losses, presenting severe health risks to patients. Furthermore, heterogeneous biofilms consisting of different bacterial species can induce the increase in pathogenicity, and the resistance to antimicrobial agents due to the synergistic interactions between the different species. Heterogeneous bacterial biofilms are notoriously difficult to treat due to the presence of extracellular polymeric substances (EPS) and, in conjunction with the rapid rise of multi-drug resistant pathogens, this means that new solutions for anti-biofilm treatment are required. In this study, we investigate the application of magneto-responsive gallium-based liquid metal (GLM-Fe) nanomaterials against a broad range of Gram-positive and Gram-negative bacterial mono-species and multi-species biofilms. The GLM-Fe particles exhibit a magneto-responsive characteristic, causing spherical particles to undergo a shape transformation to high-aspect-ratio nanoparticles with sharp asperities in the presence of a rotating magnetic field. These shape-transformed particles are capable of physically removing bacterial biofilms and rupturing individual cells. Following treatment, both mono-species and multi-species biofilms demonstrated significant reductions in their biomass and overall cell viability, demonstrating the broad-spectrum application of this antibacterial technology. Furthermore, the loss of integrity of the bacterial cell wall and membranes was visualized using a range of microscopy techniques, and the leakage of intracellular components (such as nucleic acids and protein) was observed. Insights gained from this study will impact the design of future liquid metal-based biofilm treatments, particularly those that rely on magneto-responsive properties.

Zinc, manganese, and copper amino acid complexes improve performance and bone characteristics of layer-type chicks under thermoneutral and cold stress conditions.

Two experiments were designed to evaluate the effect of mineral-amino acid complexes (AACM) as a partial replacement of inorganic mineral (IM) in layer-type chicks' diets. Both studies had the same dietary treatments, where in experiment 1 (Exp. 1) was conducted under thermoneutral conditions from 0 to 35 D and chicks in experiment 2 (Exp. 2) were exposed to cold stress conditions at nighttime during the first 15 D and to thermoneutral condition from 16 to 35 D. For each trial, 1,200 one-day-old Lohmann Brown chicks were used, with 20 cage replicates with 30 chicks per cage. Treatments consisted of the control diet (IM; with 70, 70, and 8 mg/kg of zinc [Zn], manganese [Mn], and copper [Cu], respectively) and the treatment diet (AACM, with 40, 40, and 2.75 mg/kg of Zn, Mn, and Cu, respectively, from IM sources, along with 30, 30, and 5.25 mg/kg of Zn, Mn, and Cu, respectively). Data were submitted to analysis of variance, and means were compared using the t-test (P < 0.05). In Exp. 1, there were no significant differences between treatments on chick performance. However, AACM-fed chicks had higher thymus (P = 0.03) and cecum weight (P < 0.01), superior micromineral deposition in the tibias (P < 0.01), and reduced phosphorus excretion (P = 0.03). In Exp. 2, chicks fed with AACM had higher body weight gain (P = 0.04), better average daily feed intake (P = 0.03), lower phosphorus excretion (P = 0.02), and higher liver and pancreas weight (P < 0.01) in the last week of the study. In conclusion, chicks fed with AACM under thermoneutral conditions had higher bone mineralization and reduced excretion of phosphorus, and in adverse conditions, AACM improves performance and liver and pancreas weight, also reducing phosphorus excretion.

Analysis of genotoxic effects on plants exposed to high traffic volume in urban crossing intersections.

A biological assessment of environmental quality was performed using the tropical plant species Tradescantia pallida (Rose) D.R. Hunt. var. purpurea exposed to different levels of air contamination in urban intersections with high volume of vehicle traffic. Air quality (average daily levels of particulate material in the PM1, 2.5, 10 fractions) and traffic volume in crossing intersections were monitored for 30 days before the collection of plants. Frequency of micronuclei and pollen abortivity in inflorescences collected at different intersections with gradual levels of traffic volume were evaluated as biomarkers of genotoxicity. In addition, the concentrations of bioaccumulated heavy metals in the leaves of the collected plants were also investigated. The proposed biological assessment model found a positive association between the environmental variables (traffic volume; concentration of particulate material) and biological effects (leaf concentration of Cr and Cd; micronucleus frequencies and pollen abortivity).

Fluconazole analogues with metal-binding motifs impact metal-dependent processes and demonstrate antifungal activity in Candida albicans.

Azole antifungals are an important class of antifungal drugs due to their low cost, ability to be administered orally, and broad-spectrum activity. However, their widespread and long-term use have given rise to adaptation mechanisms that render these compounds less effective against common fungal pathogens, including Candida albicans. New antifungals are desperately needed as drug-resistant strains become more prevalent. We recently showed that copper supplementation potentiates the activity of the azole antifungal fluconazole against the opportunistic fungal pathogen C. albicans. Here, we report eight new azole analogues derived from fluconazole in which one triazole group has been replaced with a metal-binding group, a strategy designed to enhance potentiation of azole antifungal activity by copper. The bioactivity of all eight compounds was tested and compared to that of fluconazole. Three of the analogues showed activity against C. albicans and two had lower levels of trailing growth. One compound, Flu-TSCZ, was found to impact the levels, speciation, and bioavailability of cellular metals.

Metal ions and graphene-based compounds as alternative treatment options for burn wounds infected by antibiotic-resistant Pseudomonas aeruginosa.

Burn infections caused by Pseudomonas aeruginosa pose a major complication in wound healing. This study aimed to determine the antimicrobial effect of metal ions, graphene (Gr), and graphene oxide (GO), individually and in combination, against the planktonic and biofilm states of two antimicrobially resistant clinical strains of P. aeruginosa each with different antibiotic resistance profiles. Minimum inhibitory, minimum bactericidal, and fractional inhibitory concentrations were performed to determine the efficacy of the metal ions and graphene composites individually and their synergy in combination. Crystal violet biofilm and XTT assays measured the biofilm inhibition and metabolic activity, respectively. Molybdenum, platinum, tin, gold, and palladium ions exhibited the greatest antimicrobial activity (MIC = 7.8-26.0 mg/L), whilst GO and Gr demonstrated moderate-to-no effect against the planktonic bacterial cells, irrespective of their antibiograms. Biofilms were inhibited by zinc, palladium, silver, and graphene. In combination, silver-graphene and molybdenum-graphene inhibited both the planktonic and biofilm forms of the bacteria making them potential candidates for development into topical antimicrobials for burns patients infected with antibiotic-resistant P. aeruginosa.

Ocean acidification: synergistic inhibitory effects of protons and heavy metals on 45Ca uptake by lobster branchiostegite membrane vesicles.

Previous work with isolated outer membrane vesicles of lobster branchiostegite epithelial cells has shown that 45Ca2+ uptake by these structures is significantly (p < 0.02) reduced by an incremental decrease in saline pH (increased proton concentration) and that this decrease is due to competitive inhibition between carrier-mediated transport of 45Ca2+ and hydrogen ions. The present paper extends these previous findings and describes the combined effects of pH and cationic heavy metals on branchiostegite uptake of 45Ca2+. Partially purified membrane vesicles of branchiostegite cells were produced by a homogenization/centrifugation method and were loaded with mannitol at pH 7.0. The time course of 1 mM 45Ca2+ uptake in a mannitol medium at pH 8.5 containing 100 µM verapamil (Ca2+ channel blocker) was hyperbolic and approached equilibrium at 30 min. This uptake was either significantly reduced (p < 0.05) by the addition of 5 µM Zn2+ or essentially abolished with the addition of 5 µM Cu2+. Increasing zinc concentrations (5-500 µM) reduced 1 mM 45Ca2+ uptake at pH 8.5 or 7.5 in a hyperbolic fashion with the remaining non-inhibited uptake due to apparent non-specific binding. Uptake of 1 mM 45Ca2+ at pH 8.5, 7.5, 7.5 + Zn2+, and 7.5 + Zn2+ + Cu2+ + Cd2+ in the presence of 100 µM verapamil displayed a stepwise reduction of 45Ca2+ uptake with the addition of each treatment until only non-specific isotope binding occurred with all cation inhibitors. 45Ca2+ influxes (15 s uptakes; 0.25-5.0 mM calcium + 100 µM verapamil) in the presence and absence of 10 µM Zn2+ were both hyperbolic functions of calcium concentration. The curve with Zn2+ displayed a transport Km twice that of the control (p < 0.05), while inhibitor and control curve Jmax values were not significantly different (p > 0.05), suggesting competitive inhibition between 45Ca2+ and Zn2+ influxes. Analysis of the relative inhibitory effects of increased proton or heavy metal interaction with 45Ca2+ uptake suggests that divalent metals may reduce the calcium transport about twice as much as a drop in pH, but together, they appear to abolish carrier-mediated transport.

Testing Metal Sensitivity of A. baumannii Strains: Survival in Copper-Supplemented Liquid Media and on Copper-Containing Surfaces.

This chapter describes protocols for determining A. baumannii isolates' overall levels of sensitivity to heavy metals; copper is used as a model heavy metal. Measurements of the ability of strains to grow in the presence of various concentrations of copper in liquid media and on copper-containing surfaces are described.

Ayurveda metallic-mineral 'Bhasma'-associated severe liver injury.

Ayurveda Bhasma is a metallic-mineral preparation homogenised with herbal juices or decoctions and modified with heat treatment to apparently detoxify the heavy metals. It is widely recommended for the treatment of many disease conditions by practitioners of complementary and alternative medicine in the absence of good quality clinical trial evidence on its safety and efficacy. Heavy metal-induced liver injury is widely reported in the literature, and heavy metal adulteration of non-Bhasma-related Ayurveda and herbal products has been well described. We report a patient who developed severe liver injury requiring listing for liver transplantation for improved survival, after consumption of Bhasma for dyspepsia. This case describes the first documented case and toxicology analysis of Ayurveda Bhasma associated with severe drug-induced liver injury. Physicians must be alert regarding patient's use of supposedly safe Ayurveda Bhasma that may promote acute severe liver injury in the absence of other known aetiologies.

Characterization and Antimicrobial Property of Some Heavy Metals Containing Ayurvedic Drugs.

Ayurvedic medicines are often used in different formulations, the heavy metals, which are generally referred to as being toxic. In this work, we report on the physicochemical characterization and biological activity of some typical Ayurvedic drugs available in the market that contain arsenic, mercury and lead with the emphasis on their antibacterial performance. Among the formulations studied, some of the drugs with 'amorphous' texture (and higher solubility) were found quite active against some bacterial strains whereas the formulations possessing crystalline texture (and low solubility) were found practically ineffective. The moderate activity of some drugs against Gram-negative bacteria fairly suggested the presence of the small-sized polar molecules which was also supported by the FTIR spectroscopic data.

Sensitive Detection of RNase A Activity and Collaborative Drug Screening Based on rGO and Fluorescence Probe.

In addition to being an important object in theoretical and experimental studies in enzymology, RNase A also plays an important role in the development of many kinds of diseases by regulating various physiological or pathological processes, including cell growth, proliferation, differentiation, and invasion. Thus, it can be used as a useful biomarker for disease theranostics. Here, a simple, sensitive, and low-cost assay for RNase A was constructed by combining a fluorogenic substrate with reduced graphene oxide (rGO). The method with detection limit of 0.05 ng/mL was first applied for RNase A targeted drug screening, and 14 natural compounds were identified as activators of this enzyme. Then, it was applied to detect the effect of drug treatment and Hepatitis B virus (HBV) infection on RNase A activity. The results indicated that RNase A level in tumor cells was upregulated by G-10 and Chikusetsusaponin V in a concentration-dependent manner, while the average level of RNase A in the HBV infection group was significantly inhibited compared with that in the control group. Furthermore, the concentration-dependent inhibitory effect of heavy metal ions on RNase A was observed using the method and the results indicated that Ba2+, Co2+, Pb2+, As3+, and Cu2+ inhibited RNase A activity with IC50 values of 93.7 µM (Ba2+), 90.9 µM (Co2+), 110.6 µM (Pb2+), 171.5 µM (As3+), and 165.1 µM (Cu2+), respectively. In summary, considering the benefits of rapidity and high sensitivity, the method is practicable for RNase A assay in biosamples and natural compounds screening in vitro and in vivo.

Effect of medicinal plants, Heavy metals and antibiotics against pathogenic bacteria isolated from raw, Boiled and pasteurized milk.

Present study has been undertaken to isolate and identify the bacterial flora in raw, boiled and pasteurized milk. Agar disc diffusion method was used to determine their sensitivity using medicinal plants, antibiotics and heavy metals. Methylene blue reduction test was used to test the quality of milk samples. Total 10 pathogenic strains were isolated, five strains were isolated from raw milk, three from boiled milk and 2 two from pasteurized milk. To determine optimum conditions for growth, these pathogenic microorganisms were incubated at various temperatures and pH. Gram's staining and biochemical tests revealed that these pathogenic bacteria include Lactobacillus sp., E. coli, Salmonella sp., Pseudomonas sp., Streptococcus sp. and Staphylococcus. Ribotyping revealed S2 as Pseudomonas fluorescens, S5 as Lactococcus lactis and S9 as Lactobacillus acidophilus. Prevalence of pathogenic organisms provided the evidence that contamination of milk arises during milking, transportation and storage of milk. Raw milk is more contaminated than other two types of milk because it contains highest percentage of pathogenic organisms and pasteurized milk was found to be of best quality among three types. So it is recommended to drink milk after proper boiling or pasteurization. Proper pasteurization and hygienic packing of milk is essential to minimize contamination in milk which can save human beings from many milk borne diseases. Our study suggests that antimicrobial use in animal husbandry should be minimized to reduce the hazard of antibiotic resistance. Plant extracts are better alternative against pathogenic bacteria in milk.

Antibacterial activity of different plant extracts and antibiotics on pathogenic bacterial isolates from wheat field water.

The present work was carried out to study bacterial pathogens isolated from wheat field water and also effect of some plant extracts on these bacterial pathogens. Five bacterial strains were isolated from wheat field water. Different morphological and biochemical tests were performed to identify and characterize bacterial pathogens. Among isolated strains two belonged to genus Staphylococcus sp., other two were Pseudomonas spp. and one strain belonged to genus Salmonella sp. Effect of various parameters such as temperature, pH, antibiotics and heavy metals of these pathogens were also studied. Optimum temperature for all bacterial strains was 37oC and optimum pH was 7 except strain 3 which had pH 6. Different antibiotics with different potency were applied to check the resistance of bacterial strains against them. Among these antibiotics Cloxacillin and Teicoplanin were most potent while Oxacillin was as less potent antibiotic because three bacterial strains were resistant against it. While remaining antibiotics proved as potent. Seven heavy metals which were zinc (Zn+2), copper (Cu+2), Ferrous (Fe+2), mercury (Hg+2), Nickel (Ni+2), chromium (Cr+2) and cobalt (Co+2) with different concentrations were applied to bacterial strains. Minimum inhibitory concentration of heavy metals for all bacterial was different. Different plant extracts (Artemezia incise, Colebrookia oppositifolia, Rhynchosia pseudocajan) checked for their antibacterial activity against these pathogens. These plant extracts showed antibacterial activity against antibiotic and metal resistant bacterial isolates.