N-acetyl-cysteine mitigates arsenic stress in lettuce: Molecular, biochemical, and physiological perspective.

Agricultural land contaminated with heavy metals such as non-biodegradable arsenic (As) has become a serious global problem as it adversely affects agricultural productivity, food security and human health. Therefore, in this study, we investigated how the administration of N-acetyl-cysteine (NAC), regulates the physio-biochemical and gene expression level to reduce As toxicity in lettuce. According to our results, different NAC levels (125, 250 and 500 µM) significantly alleviated the growth inhibition and toxicity induced by As stress (20 mg/L). Shoot fresh weight, root fresh weight, shoot dry weight and root dry weight (33.05%, 55.34%, 17.97% and 46.20%, respectively) were decreased in plants grown in As-contaminated soils compared to lettuce plants grown in soils without the addition of As. However, NAC applications together with As stress increased these growth parameters. While the highest increase in shoot fresh and dry weight (58.31% and 37.85%, respectively) was observed in 250 µM NAC application, the highest increase in root fresh and dry weight (75.97% and 63.07%, respectively) was observed in 125 µM NAC application in plants grown in As-polluted soils. NAC application decreased the amount of ROS, MDA and H2O2 that increased with As stress, and decreased oxidative damage by regulating hormone levels, antioxidant and enzymes involved in nitrogen metabolism. According to gene expression profiles, LsHIPP28 and LsABC3 genes have shown important roles in reducing As toxicity in leaves. This study will provide insight for future studies on how NAC applications develop resistance to As stress in lettuce.

Drought stress amelioration in tomato (Solanum lycopersicum L.) seedlings by biostimulant as regenerative agent.

Drought adversely affects many physiological and biochemical events of crops. This research was conducted to investigate the possible effects of biostimulants containing plant growth-promoting rhizobacteria (PGPR) on plant growth parameters, chlorophyll content, membrane permeability (MP), leaf relative water content (LRWC), hydrogen peroxide (H2O2), proline, malondialdehyde (MDA), hormone content, and antioxidant enzymes (catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD)) activity of tomato (Solanum lycopersicum L.) seedlings under different irrigation levels. This study was carried out under controlled greenhouse conditions with two irrigation levels (D0: 100% of field capacity and D1: 50% of field capacity) and three biostimulant doses (B0: 0, B1: 4 L ha-1, and B2: 6 L ha-1). The results of the study show that drought stress negatively influenced the growth and physiological characteristics of tomato seedlings while biostimulant applications ameliorated these parameters. Water deficit conditions (50% of field capacity) caused decrease in indole acetic acid (IAA), gibberellic acid (GA), salicylic acid (SA), cytokine, zeatin, and jasmonic acid content of tomato seedlings by ratios of 83%, 93%, 82%, 89%, 50%, and 57%, respectively, and shoot fresh weight, root fresh weight, shoot dry weight, root dry weight, plant height, stem diameter, and leaf area decreased by 43%, 19%, 39%, 29%, 20%, 18%, and 50%, respectively, compared to the control (B0D0). In addition, 21%, 16%, 21%, and 17% reductions occurred in LRWC, chlorophyll a, chlorophyll b, and total chlorophyll contents with drought compared to the control, respectively. Biostimulant applications restored the plant growth, and the most effective dose was 4 L ha-1 under drought condition. Amendment of biostimulant into the soil also enhanced organic matter and the total N, P, Ca, and Cu content of the experiment soil. In conclusion, 4 L ha-1 biostimulant amendment might be a promising approach to mitigate the adverse effects of drought stress on tomato.

Biosynthesis of capsaicinoids in pungent peppers under salinity stress.

The synthesis of capsaicinoids occurs in the placenta of the fruits of pungent peppers. However, the mechanism of capsaicinoids' biosynthesis in pungent peppers under salinity stress conditions is unknown. The Habanero and Maras genotypes, the hottest peppers in the world, were chosen as plant material for this study, and they were grown under normal and salinity (5 dS m-1 ) conditions. The results showed that salinity stress harmed plant growth but increased the capsaicin content by 35.11% and 37.00%, as well as the dihydrocapsaicin content by 30.82% and 72.89% in the fruits of the Maras and Habanero genotypes, respectively, at 30 days after planting. The expression analysis of key genes in capsaicinoids biosynthesis revealed that the PAL1, pAMT, KAS, and PUN1 genes were overexpressed in the vegetative and reproductive organs of pungent peppers under normal conditions. However, under salinity stress, overexpression of PAL1, pAMT, and PUN1 genes was identified in the roots of both genotypes, which was accompanied by an increase in capsaicin and dihydrocapsaicin content. The findings showed that salinity stress caused an enhancement in the capsaicin and dihydrocapsaicin contents in the roots, leaves, and fruits of pungent peppers. Nonetheless, it was found that the production of capsaicinoids is generally not restricted to the fruits of pungent peppers.

Mitigation of salinity stress in cucumber seedlings by exogenous hydrogen sulfide.

This research hypothesized that tolerance of cucumber seedlings to salinity stress could be increased by hydrogen sulfide (H2S) treatments. In pot experiments, the cucumber seedlings were exposed to three levels of salt stress (0, 50 and 100 mM NaCl), and NaHS as H2S donor was foliar applied to the cucumber seedlings at five different doses (0, 25, 50, 75 and 100 µM). The effects of the treatments on cucumber seedlings were tested with plant growth properties as well as physiological and biochemical analyses. As the salinity level increased, plant growth properties and chlorophyll reading value (SPAD) decreased. However, H2S treatments significantly mitigated the impact of salinity. Salt stress elevated the membrane permeability (MP) and decreased the leaf relative water content (LRWC). H2S applied leaves had lower MP and higher LRWC than non-H2S applied leaves. On the other hand, photosynthetic properties (net photosynthetic rate, stomatal conductance, transpiration rate and intercellular CO2 concentration) of the seedlings under salt stress conditions were decreased but this decrease was considerably relieved by H2S treatment. The K/Na and Ca/Na ratios under salt stress conditions were higher in H2S-applied plants than in non-applied plants. Furthermore, antioxidant enzyme activity [(catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD)] and hydrogen peroxide (H2O2), malondialdehyde (MDA), proline, and sucrose concentration in the leaves increased with salinity stress whereas they were reduced with H2S treatments under salt stress. Mitigation of salt stress damage in cucumber using H2S treatment can be expounded via modulation of enzyme activity, nutrient content, reactive oxygen species (ROS) formation, and osmolytes accumulation.

Effects of Tooth Brushing and MouthWashing on Leaching Bisphenol A Levels From an Orthodontic Adhesive: An In Vitro Study.

OBJECTIVE: To assess the levels of bisphenol A (BPA) released from an orthodontic adhesive with respect to the effects of tooth brushing and mouth washing. METHODS: Three groups, each containing fifteen adhesive samples were prepared. In Group 1, samples were polymerized according to manufacturer instructions. In Group 2, after the same polymerization protocol, each sample was brushed with a fluoride-containing toothpaste. For Group 3, samples were immersed in a mouth washing solution after polymerization. Later, all samples were placed into glass tubes containing 5 mL distilled water. High-performance liquid chromatography (HPLC) measurements were performed to assess the leaching amount of BPA. Intergroup comparison was performed by one way ANOVA test. RESULTS: Mean amounts of BPA were found to be 0.2674 µg/L, 0.2692 µg/L, and 0.2705 µg/L, respectively. Only a significant difference was found between Group 1 and 3 (P < .01), revealing higher BPA levels with the mouth washing solution. CONCLUSION: Measurable amounts of BPA release were observed in all groups of orthodontic adhesive samples, but the detected amounts were below the toxic levels. From a clinical point of view, alcohol-containing mouth washing solutions might increase the amount of leaching monomer, since alcohol is solvent of BPA.

New approaches with ATR-FTIR, SEM, and contact angle measurements in the adaptation to extreme conditions of some endemic Gypsophila L. taxa growing in gypsum habitats.

Gypsophila L. taxa growing on gypsum soils have to withstand limiting and restrictive conditions for plant life. This study aims to identify functional mechanisms determine the main functional groups in the vegetative and reproductive organs of some endemic Gypsophila taxa growing in gypsum soils, as well as to understand the relationship between the hidrophobicities and their micromorphological structures of the leaves of these plants grown in arid conditions. In this context, a series of Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR), water contact angle (CA) measurements, and scanning electron microscopy (SEM) analyses were performed that may help to understand the survival mechanisms of Gypsophila eriocalyx Boiss., Gypsophila germanicopolitana Hub.-Mor. and Gypsophila simonii Hub.-Mor. growing in gypsum habitats. Our results showed the presence of O-H and C-O stretching bands belong to gypsum and calcium oxalate in the roots, stems, leaves and flowers of Gypsophila taxa is thought to be a way of tolerating the excess Ca and sulphate in the extreme habitat where these species grow. Leaves of Gypsophila taxa showed CAs above 90°, which indicates that G. eriocalyx, G. germanicopolitana, and G. simonii were hydrophobic. This study offers new approaches to understanding the adaptation of Gypsophila taxa to the extreme conditions typical of gypsum soils. The characterization of gypsum plants such as Gypsophila taxa, whose mechanisms for competition and survival on gypsum are still not fully understood, is very important in terms of shedding light on the adaptation of endemic plants to gypsum habitats.

Humic + Fulvic acid mitigated Cd adverse effects on plant growth, physiology and biochemical properties of garden cress.

Cadmium (Cd) is a toxic and very mobile heavy metal that can be adsorbed and uptaken by plants in large quantities without any visible sign. Therefore, stabilization of Cd before uptake is crucial to the conservation of biodiversity and food safety. Owing to the high number of carboxyl and phenolic hydroxyl groups in their structure, humic substances form strong bonds with heavy metals which makes them perfect stabilizing agents. The aim of this study was to determine the effects of humic and fulvic acid (HA + FA) levels (0, 3500, 5250, and 7000 mg/L) on alleviation of Cadmium (Cd) toxicity in garden cress (Lepidium sativum) contaminated with Cd (CdSO4.8H2O) (0, 100, and 200 Cd mg/kg) under greenhouse conditions. Our results showed that, Cd stress had a negative effect on the growth of garden cress, decreased leaf fresh, leaf dry, root fresh and root dry weights, leaf relative water content (LRWC), and mineral content except for Cd, and increased the membrane permeability (MP) and enzyme (CAT, SOD and POD) activity. However, the HA + FA applications decreased the adverse effects of the Cd pollution. At 200 mg/kg Cd pollution, HA + FA application at a concentration of 7000 mg/L increased the leaf fresh, leaf dry, root fresh, root dry weights, stem diameter, leaf area, chlorophyll reading value (CRV), MP, and LRWC values by 262%, 137%, 550%,133%, 92%, 104%, 34%, 537%, and 32% respectively, compared to the control. Although the highest H2O2, MDA, proline and sucrose values were obtained at 200 mg/L Cd pollution, HA + FA application at a concentration of 7000 mg/L successfully alleviated the deleterious effects of Cd stress by decreasing H2O2, MDA, proline, and sucrose values by 66%, 68%, 70%, and 56%, respectively at 200 mg/kg Cd pollution level. HA + FA application at a concentration of 7000 mg/L successfully mitigated the negative impacts of Cd pollution by enhanced N, P, K, Ca, Mg, Fe, Mn, Cu, Mn, Zn, and B by 75%, 23%, 84%, 87%, 40%, 85%, 143%, 1%, 65%, and 115%, respectively. In addition, HA + FA application at a concentration of 7000 mg/L successfully reduced Cd uptake by 95% and Cl uptake by 80%. Considering the plant growth parameters, the best results were determined when HA + FA concentration was 7000 mg/L. We have shown that, it is critical to apply a humic substance with high percentage of FA, which was 10% in this study, to mitigate the adverse effects of heavy metal stress on plant growth. In conclusion, the application of HA + FA may be suggested as an effective solution for reducing the Cd uptake of the plants by stabilizing Cd in soil and preventing translocation of Cd from the roots of plant to its shoot and leaves.

Nitric oxide mitigates salt stress effects of pepper seedlings by altering nutrient uptake, enzyme activity and osmolyte accumulation.

This study was planned to evaluate the role of exogenous application of sodium nitroprusside (SNP), a NO donor, on the deleterious effect of salinity in Capsicum annum L. seedlings. Different NO doses (0, 50, 100 and 150 µM SNP) were foliarly applied to pepper seedlings grown under the non-saline and saline conditions (50, 100 and 150 mM of NaCl). The photosynthetic rate (Pn), stomatal conductance (gs), intercellular CO2 concentration (Ci), transpiration rate (Tr), mineral element (Zn, Fe, B, K, Ca and Mg) uptake, plant growth and leaf relative water content (LRWC) were decreased by NaCl treatment, but NO treatments generally improved the observed parameters. 150 mM NaCl treatment caused overaccumulation of hydrogen peroxide (H2O2) and malondialdehyde (MDA) by 87 and 100% respectively as compared to control. However, NO application (150 µM SNP) at 150 mM of NaCl significantly decreased H2O2 and MDA to 34 and 54%, respectively. The present study clarified that the exogenous NO treatment supported pepper seedlings against salinity stress by regulating the mineral nutrient uptake, antioxidant enzyme activity, osmolyte accumulation, and improving the LRWC and photosynthetic activity.

Molecularly imprinted superparamagnetic iron oxide nanoparticles for rapid enrichment and separation of cholesterol.

A general protocol to prepare surface molecularly imprinted polymer core-shell superparamagnetic Fe3O4 nanoparticles (Fe3O4@MIP SPNPs), using a surface-mediated RAFT polymerization approach, is described. Cholesterol-imprinted Fe3O4@MIP SPNPs were obtained by oleic acid-stabilized Fe3O4 nanoparticles with a trithiocarbonate agent and subsequently by polymerizing thin molecularly imprinted layers composed of dimethylacrylamide and N,N'-methylene(bis)acrylamide units. The surface-mediated RAFT polymerization approach allows the synthesis of ∼20 nm hybrid composite particles with a ∼6 nm MIP shell, exhibiting superparamagnetic properties (saturation magnetization = 35.4 emu g(-1)) and specific molecular recognition of cholesterol. The Fe3O4@MIP SPNPs show the capability of rapid enriching and separating cholesterol (∼3.1% in weight) and are renewable and cyclically exploited due to their monodispersive and superparamagnetic features. Moreover, under optimal conditions, the Fe3O4@MIP SPNP recoveries of spiked human serum, milk, yolk and beef were 91.6%, 93.6%, 92.4% and 91.2%, respectively. Finally, the method of molecular imprinting on superparamagnetic particles can be extended to a wide range of applications for cell sorting, biomolecule enrichment and separation, and drug delivery.