Melatonin-mediated endogenous nitric oxide coordinately boosts stability through proline and nitrogen metabolism, antioxidant capacity, and Na+/K+ transporters in tomato under NaCl stress

The interactions between nitric oxide (NO) and melatonin in alleviating sodium chloride (NaCl) toxicity in plants are poorly comprehended. Here, the associations between the exogenous application of melatonin and endogenous NO levels in inducing tomato seedlings' defense response during NaCl toxicity were investigated. The results indicated that the application of melatonin (150 μM) increased height (23.7%) and biomass (32.2%), improved chlorophyll (a (137%) and b (92.8%)), and proline metabolisms, and reduced the contents of superoxide anion radicals (49.6%), hydrogen peroxide (31.4%), malondialdehyde (38%), and electrolyte leakage (32.6%) in 40-day-old tomato seedlings grown under NaCl (150 mM) treatment. Melatonin increased the antioxidant defense system in NaCl-stressed seedlings by increasing the activity of the antioxidant enzymes. Melatonin also improved N metabolism and endogenous NO content in NaCl-stressed seedlings by upregulating the activity of enzymes implicated in N assimilation. Furthermore, melatonin improved ionic balance and reduced Na content in NaCl-exposed seedlings by upregulating the expression of genes involved in K/Na ratio homeostasis (NHX1-4) and increasing the accumulation of mineral nutrients (P, N, Ca, and Mg). However, the addition of cPTIO (100 μM; an NO scavenger) reversed the beneficial impacts of melatonin, indicating the effective function of NO in melatonin-induced defense mechanisms in NaCl-stressed tomato seedlings. Therefore, our results revealed that melatonin improves the tolerance of tomato plants during NaCl toxicity by mediating internal NO.

Effects of silicon and titanium dioxide nanoparticles on arsenic accumulation, phytochelatin metabolism, and antioxidant system by rice under arsenic toxicity

Arsenic (As) is known to be one of the most toxic metalloids for humans and plants; however, little is known about the use of silicon (Si) and titanium dioxide (TiO₂) nanoparticles (NPs) in reducing As toxicity in rice (Oryza sativa L.). The experiment was conducted to examine the effects of Si-NPs (50 and 100 mg/L), TiO₂-NPs (25 and 50 mg/L) and As (50 µM) on growth, photosynthetic pigments, antioxidant defense system, glyoxalase system, expression of Si/As transporters, and genes involved in As sequestration in rice under hydroponic conditions. The results revealed that Si- and TiO₂-NPs by upregulating the activity of antioxidant enzymes and glyoxalase cycle reduced hydrogen peroxide, methylglyoxal, malondialdehyde, and electrolyte leakage, and thus protected the photosynthetic apparatus and improved plant growth under As stress. By increasing the expression of GSH1, PCS, and ABC1 genes, Si- and TiO₂-NPs increased leaf and root accumulation of glutathione and phytochelatins and sequestered As in vacuoles, which protected plant cells from As toxicity. Si-NPs diminished As uptake and increased Si uptake in As-exposed rice plants by modulating the expression of Si/As transporters (Lsi1, Lsi2, and Lsi6). The results depicted that 100 mg/L Si-NPs treatment had the highest positive effect on plant growth and tolerance under As stress compared to other treatments. In general, Si- and TiO₂-NPs augmented the growth of rice under As stress through different strategies, which can be used to design effective fertilizers to enhance the crop growth and yield in areas contaminated with toxic metals.

Foliar application of Zinc oxide nanoparticles alleviates cadmium toxicity in purslane by maintaining nutrients homeostasis and improving the activity of antioxidant enzymes and glyoxalase system

Cadmium (Cd) reduces plant growth by interfering with important plant metabolic processes at the physiological, biochemical, and molecular levels. Here, the effects of foliar application of zinc oxide nanoparticles (ZnO-NPs) on growth, antioxidant enzymes, glyoxalase system, and macro- and micro-elements levels of purslane (portulaca oleracea L.) under Cd toxicity were investigated. The results revealed that Cd toxicity increased the levels of hydrogen peroxide (H₂O₂), methylglyoxal (MG) and malondialdehyde (MDA), resulting in oxidative stress and the induction of electrolyte leakage (EL). Cd stress enhanced the leaf concentration of Cd and declined the leaf concentrations of macro- and micro-elements, resulting in a decrease in the content of photosynthetic pigments and plant growth. However, the foliar application of ZnO-NPs improved the activity of antioxidant enzymes and the glyoxalase system and, consequently, reduced the levels of H₂O₂, MG, MDA, and EL in Cd-stressed plants. ZnO-NPs decreased the leaf concentration of Cd and restored the leaf concentrations of macro- and micro-elements, thereby improving photosynthetic pigments and the growth of Cd-stressed purslane plants. In general, the results revealed that the foliar application of ZnO-NPs improved the growth of purslane plants under Cd phytotoxicity by maintaining nutrient homeostasis, improving the defense mechanisms (antioxidant enzymes and glyoxalase cycle), and increasing the accumulation of proline and glutathione. Therefore, the results of the present study strongly recommend that ZnO-NPs could be used effectively in the cultivation of plants in areas contaminated with toxic Cd metal.

Nitric oxide could allay arsenic phytotoxicity in tomato (Solanum lycopersicum L.) by modulating photosynthetic pigments, phytochelatin metabolism, molecular redox status and arsenic sequestration

Plants do not always have the genetic capacity to tolerate high levels of arsenic (As), which may not only arrest their growth but pose potential health risks through dietary bioaccumulation. Meanwhile, the interplay between the tomato plants and As-NO-driven molecular cell dynamics is obscure. Accordingly, seedlings were treated with As (10 mg/L) alone or in combination with 100 μM sodium nitroprusside (SNP, NO donor) and 200 μM 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO, NO scavenger). Sodium nitroprusside immobilized As in the roots and reduced the shoot translocation by up-regulating the transcriptional expression of the PCS, GSH1, MT2, and ABC1. SNP further restored the growth retardation through modulating the chlorophyll and proline metabolism, increasing NO accumulation and stomatal conductance along with clear crosstalk between the antioxidant activity as well as glyoxalase I and II leading to endogenous H₂O₂ and MG reduction. Higher PCs and glutathione accumulation helped protect photosynthetic apparatus; however, cPTIO reversed the protective effects of SNP, confirming the role of NO in the As toxicity alleviation.

Nitric oxide could allay arsenic phytotoxicity in tomato (Solanum lycopersicum L.) by modulating photosynthetic pigments, phytochelatin metabolism, molecular redox status and arsenic sequestration

Plants do not always have the genetic capacity to tolerate high levels of arsenic (As), which may not only arrest their growth but pose potential health risks through dietary bioaccumulation. Meanwhile, the interplay between the tomato plants and As-NO-driven molecular cell dynamics is obscure. Accordingly, seedlings were treated with As (10 mg/L) alone or in combination with 100 μM sodium nitroprusside (SNP, NO donor) and 200 μM 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO, NO scavenger). Sodium nitroprusside immobilized As in the roots and reduced the shoot translocation by up-regulating the transcriptional expression of the PCS, GSH1, MT2, and ABC1. SNP further restored the growth retardation through modulating the chlorophyll and proline metabolism, increasing NO accumulation and stomatal conductance along with clear crosstalk between the antioxidant activity as well as glyoxalase I and II leading to endogenous H₂O₂ and MG reduction. Higher PCs and glutathione accumulation helped protect photosynthetic apparatus; however, cPTIO reversed the protective effects of SNP, confirming the role of NO in the As toxicity alleviation.

Cytotoxic Effect of Portulaca Oleracea Extract on the Regulation of CDK1 and P53 Gene Expression in Pancreatic Cancer Cell Line

The growth of pancreatic cancer has a high predominance in the world. Different therapeutic methods were unsuccessful due to tumor invasion and rapid metastasis. Plants have natural products that were used as therapeutic agents. Accordingly, the purpose of this research was to assess the cytotoxic effect of Portulaca Oleracea against PANC-1 cancer cell line. MTT technique and flow cytometry were done to evaluate the cytotoxicity of P.Oleracea extracts against PANC-1 cancer cell line. For finding the change of CDK and P53 expression levels, qPCR carries out. The findings of the MTT assay exhibited that P.Oleracea extracts had toxicity potential on PANC- one cancer cell line. Also, the results of gene expression showed the high expression of P53 and reduction of CDK gene expression following treatment of cancer cells with plant extracts in. The flow cytometry assay showed apoptosis induced after P.Oleracea extract treatment in PANC- one cancer cell line. Also, microscopic observation is in agreement with flow cytometry and MTT assay. Results of the current study indicated that P.Oleracea extracts significantly induce apoptosis by regulating P53 and CDK expression, consequently. Therefore, P.Oleracea may be considered as a novel finding for pancreatic cancer treatment consequently of its cytotoxic and apoptotic activity.

Piriformospora indica augments arsenic tolerance in rice (Oryza sativa) by immobilizing arsenic in roots and improving iron translocation to shoots

Arsenic (As) toxicity can be a hazardous threat to sustainable agriculture and human health. Piriformospora indica (P. indica), as a beneficial endophytic fungus, is involved in the plant tolerance to stressful conditions. Here, the biochemical and molecular responses of rice plants to As (50 μM) phytotoxicity and P. indica inoculation as well as the role of P. indica in improving rice adaptation to As stress were evaluated. The results showed that As stress reduced chlorophylls content, chlorophyll fluorescence yield (Fv/Fm), electron transport rate (ETR) and growth. However, P. indica restored chlorophyll content and growth. P. indica decreased the contents of methylglyoxal and malondialdehyde by improving the activity of enzymes involved in the glyoxalase pathway and modulating the redox state of the ascorbic acid-glutathione cycle, and consequently, increased the plant tolerance to As toxicity. P. indica, by downregulating Lsi2 expression (involved in As translocation to the shoot) and upregulating PCS1 and PCS2 expression (involved in As sequestration in vacuoles), immobilized As in the roots and reduced damage to photosynthetic organs. P. indica increased iron (Fe) accumulation in the shoot under As toxicity by upregulating the expression of IRO2, YSL2 and FRDL1 genes. The results of the present study augmented our knowledge in using P. indica symbiosis in improving the tolerance of rice plants against As toxicity for sustainable agriculture.

Phytotoxicity of green synthesized silver nanoparticles on Camelina sativa L

Due to the increased production and release of silver nanoparticles (AgNPs) in the environment, the concerns about the possibility of toxicity and oxidative damage to plant ecosystems should be considered. In the present study, the effects of different concentrations of AgNPs (0, 0.5, 1, 2, 3 and 4 g/L) synthesized using the extract of camelina (Camelina sativa) leaves on the growth and the biochemical traits of camelina seedlings were investigated. The results showed that AgNPs significantly increased Ag accumulation in the roots and shoots which decreased the growth and photosynthetic pigments of camelina seedlings. The highest decrease in the height and total dry weight was observed by 53.1 and 61.8% under 4 g/L AgNPs, respectively over control plants. AgNPs application over 2 g/L enhanced the accumulation of proline, malondialdehyde, hydrogen peroxide and methylglyoxal, and up-regulated the activity of antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase) and glyoxalase (glyoxalase I and II) system which indicates oxidative stress induction in camelina seedlings. Moreover, AgNPs reduced ASA and GSH contents and increased DHA and GSSG contents, hence disrupting the redox balance. These results showed that AgNPs at 4 g/L had the most toxic effects on the camelina growth. Therefore, increasing oxidative stress markers and the activity of antioxidant enzymes and enzymes involved in glyoxalase system indicated the oxidative stress induced by AgNPs treatments over 2 g/L as well as the induction of antioxidant defense systems to combat AgNPs-induced oxidative stress.

Aberrant Expression of Peroxisome Proliferator-Activated Receptors in Colorectal Cancer and Their Association with Cancer Progression and Prognosis

INTRODUCTION

Peroxisome proliferator-activated receptors (PPARs), PPARα, PPARγ, and PPARδ, are nuclear ligand-activated transcription factors which presumably contribute to a broad range of pathophysiological processes, such as tumorigenesis. Nevertheless, their exact role as tumor suppressors or promoters is not straightforward in colorectal cancer (CRC). Therefore, expression values of these PPARs and their relation with tumor progression and prognosis were examined in CRC patients.

METHODS

In this work, the relative expression values of the PPARs were measured by real-time polymerase chain reaction in 100 CRC tumor tissues paired with adjacent normal tissues. After that, the association between relative expression values of the PPARs in tumor tissues and the cancer progression-related clinicopathological characteristics as well as overall survival of patients were assessed.

RESULTS

While PPARα and PPARδ seemed to be overexpressed, PPARγ was suppressed in CRC tumor tissues compared with paired adjacent normal tissues (p = 0.0001). The relative expressions of PPARα and PPARδ were negatively associated with tumor size, tumor grade, TNM stage, metastasis, lymphatic invasion, and decreased overall survival time (p < 0.05). The same associations, but in reverse direction, were found for PPARγ.

CONCLUSIONS

It was found that PPARα and PPARδ were overexpressed while PPARγ was suppressed in CRC tumor tissues, and these deregulations are associated with cancer progression and poor prognosis.

Evaluation of tumor necrosis factor (TNF)-α mRNA expression level and the rs1799964 polymorphism of the TNF-α gene in peripheral mononuclear cells of patients with inflammatory bowel diseases

Crohn's disease (CD) and ulcerative colitis (UC) are types of chronic inflammatory bowel disease (IBD) of which the actual causes remain unknown. Emerging data indicate that alterations in cytokine synthesis may be involved in IBD pathogenesis. The aim of the present study was to determine whether the tumor necrosis factor (TNF)-α mRNA expression level and rs1799964 polymorphism are the genetic susceptibility component of IBD development. The TNF-α mRNA expression level of peripheral blood mononuclear cells (PBMCs) was measured using comparative reverse-transcription quantitative polymerase chain reaction (PCR). Genomic DNA from 201 individuals (CD: n=15; UC: n=86; control subjects: n=100) was analyzed for the presence of the TNF-α-1031 polymorphism by PCR-restriction fragment length polymorphism. An increased TNF-α mRNA expression level was additionally observed in the CC genotype of the -1031 TNF-α gene polymorphism compared with the TC and TT genotypes (P<0.05). Furthermore, the present results revealed that there was no significant difference in the genotype/allele frequencies of the -1031 TNF-α gene polymorphism in Iranian IBD patients. By comparison, the TNF-α mRNA expression level was evaluated in patients with a history of taking medications and demonstrated a significant association in the group that received the 5-ASA + Pred + AZA,5. 5-ASA + Pred + AZA + IFX when compared with the other groups (P<0.05). Thus, these results support the hypothesis that overexpression of the TNF-α gene, which correlated with the CC genotype, may represent a genetic risk factor for Iranian IBD.

Investigating the Interaction of Fe Nanoparticles with Lysozyme by Biophysical and Molecular Docking Studies

Herein, the interaction of hen egg white lysozyme (HEWL) with iron nanoparticle (Fe NP) was investigated by spectroscopic and docking studies. The zeta potential analysis revealed that addition of Fe NP (6.45±1.03 mV) to HEWL (8.57±0.54 mV) can cause to greater charge distribution of nanoparticle-protein system (17.33±1.84 mV). In addition, dynamic light scattering (DLS) study revealed that addition of Fe NP (92.95±6.11 nm) to HEWL (2.68±0.37 nm) increases suspension potential of protein/nanoparticle system (51.17±3.19 nm). Fluorescence quenching studies reveled that both static and dynamic quenching mechanism occur and hydrogen bond and van der Waals interaction give rise to protein-NP system. Synchronous fluorescence spectroscopy of HEWL in the presence of Fe NP showed that the emission maximum wavelength of tryptophan (Trp) residues undergoes a red-shift. ANS fluorescence data indicated a dramatic exposure of hydrophobic residues to the solvent. The considerable reduction in melting temperature (T(m)) of HEWL after addition of Fe NP determines an unfavorable interaction system. Furthermore circular dichoroism (CD) experiments demonstrated that, the secondary structure of HEWL has not changed with increasing Fe NP concentrations; however, some conformational changes occur in tertiary structure of HEWL. Moreover, protein-ligand docking study confirmed that the Fe NP forms hydrogen bond contacts with HEWL.