Proteomic analysis reveals differential responsive mechanisms in Solanum nigrum exposed to low and high dose of cadmium.

Cadmium (Cd) contamination is becoming a widespread environmental problem. However, the differential responsive mechanisms of Cd hyperaccumulator Solanum nigrum to low or high dose of Cd are not well documented. In this study, phenotypic and physiological analysis firstly suggested that the seedlings of S. nigrum showed slight leaf chlorosis symptoms under 25 µM Cd and severe inhibition on growth and photosynthesis under 100 µM Cd. Further proteomic analysis identified 105 differentially expressed proteins (DEPs) in the Cd-treated leaves. Under low dose of Cd stress, 47 DEPs are mainly involved in primary metabolic processes, while under high dose of Cd stress, 92 DEPs are mainly involved in photosynthesis, energy metabolism, production of phytochelatin and reactive oxygen species (ROS). Protein-protein interaction (PPI) network analysis of DEPs support above differential responses in the leaves of S. nigrum to low and high dose of Cd treatments. This work provides the differential responsive mechanisms in S. nigrum to low and high dose of Cd, and the theoretical foundation for the application of hyperaccumulating plants in the phytoremediation of Cd-contaminated soils.

Acute Kidney Injury and 3-Year Mortality in Elderly Patients After Non-cardiac Surgery.

Objective: The present study aimed to investigate whether acute kidney injury (AKI) was associated with 3-year mortality in elderly patients after non-cardiac surgery. Methods: The present study was a 3-year follow-up study of two randomized controlled trials. A total of 1,319 elderly patients who received non-cardiac surgery under general anesthesia were screened. AKI was diagnosed by the elevation of serum creatinine within a 7-day postoperative period according to Kidney Disease: Improving Global Outcomes (KDIGO) guidelines. A long-term telephonic follow-up was undertaken by investigators who were not involved in the previous two trials and had no access to the study group assignment. The date of death was taken from the official medical death certificate. The primary outcome was to investigate the association between AKI and postoperative 3-year mortality using the multivariable Cox regression risk model. Results: Of the 1,297 elderly patients (mean age 71.8 ± 7.2 years old) who were included in the study, the incidence of AKI was 15.5% (201/1297). Of the patients with AKI, 85% (170/201) were at stage 1, 10% (20/201) at stage 2, and 5% (11/201) at stage 3. The 3-year all-cause mortality was 28.9% (58/201) in patients with AKI and 24.0% (263/1,096) in patients without AKI (hazard ratio 1.247, 95% confidence interval 0.939-1.657, P = 0.128). The multivariable Cox regression showed that AKI was not associated with 3-year mortality after adjustment of confounding factors (adjusted hazard ratio 1.045, 95% confidence interval 0.780-1.401, P = 0.766). Conclusions: AKI was a common postoperative complication, but it was not associated with 3-year mortality in elderly patients who underwent non-cardiac surgery. The low incidence of severe AKI might underestimate its underlying association with long-term mortality.

Unearthing the alleviatory mechanisms of hydrogen sulfide in aluminum toxicity in rice.

Hydrogen sulfide (H2S) improves aluminum (Al) resistance in rice, however, the underlying mechanism remains unclear. In the present study, treatment with 30-µM Al significantly inhibited rice root growth and increased the total Al content, apoplastic and cytoplasm Al concentration in the rice roots. However, pretreatment with NaHS (H2S donor) reversed these negative effects. Pretreatment with NaHS significantly increased energy production under Al toxicity conditions, such as by increasing the content of ATP and nonstructural carbohydrates. In addition, NaHS stimulated the AsA-GSH cycle to decrease the peroxidation damage induced by Al toxicity. Pretreatment with NaHS significantly inhibited ethylene emissions in the rice and then inhibited pectin synthesis and increased the pectin methylation degree to reduce cell wall Al deposition. The phytohormones indole-3-acetic and brassinolide were also involved in the alleviation of Al toxicity by H2S. The transcriptome results further confirmed that H2S alleviates Al toxicity by increasing the pathways relating to material and energy metabolism, redox reactions, cell wall components, and signal transduction. These findings improve our understanding of how H2S affects rice responses to Al toxicity, which will facilitate further studies on crop safety.

Putrescine alleviates aluminum toxicity in rice (Oryza sativa) by reducing cell wall Al contents in an ethylene-dependent manner.

Aluminum (Al3+ ) toxicity in acidic soils limits crop productivity worldwide. In this study, we found that putrescine (PUT) significantly alleviates Al toxicity in rice roots. The addition of 0.1 mM PUT promoted root elongation and reduced the Al content in the root apices of Nipponbare (Nip) and Kasalath (Kas) rice under Al toxicity conditions. Exogenous treatment with PUT reduced the cell wall Al content by reducing polysaccharide (pectin and hemicellulose) levels and pectin methylesterase (PME) activity in roots and decreased the translocation of Al from the external environment to the cytoplasm by downregulating the expression of OsNRAT1, which responsible to encode an Al transporter protein Nrat1 (Nramp aluminum transporter 1). The addition of PUT under Al toxicity conditions significantly inhibited ethylene emissions and suppressed the expression of genes involved in ethylene biosynthesis. Treatment with the ethylene precursor 1-aminocylopropane-1-carboxylic acid (ACC) significantly improved ethylene emission, inhibited root elongation, increased the Al accumulation in root tips and the root cell wall, and increased cell wall pectin and hemicellulose contents in both rice cultivars under Al toxicity conditions. The ethylene biosynthesis antagonist aminoethoxyvinylglycine (AVG, inhibitor of the ACC synthase) had the opposite effect and reduced PME activity. Together, our results show that PUT decreases the cell wall Al contents by suppressing ethylene emissions and decreases the symplastic Al levels by downregulating OsNRAT1 in rice.

Boron reduces cell wall aluminum content in rice (Oryza sativa) roots by decreasing H2O2 accumulation.

When boron (B) deficiency and aluminum (Al) toxicity co-exist in acidic soils, crop productivity is limited. In the current study, we found that 3 µM of B pretreatment significantly enhances rice root elongation under Al toxicity conditions. Pretreatment with B significantly decreases the deposition of Al in rice apoplasts, suppresses the synthesis of cell wall pectin, inhibits cell wall pectin methylesterase (PME) activity and its gene expression, and increases the expression of OsSTAR1 and OsSTAR2, which are responsible for reducing the Al content in the cell walls. In addition, B pretreatment significantly increases OsALS1 expression, thereby facilitating the transfer of Al from the cytoplasm to the vacuoles. However, B pretreatment had no effect on Al uptake and citric acid secretion. Pretreatment with B significantly increases the activity of ascorbate peroxidase (APX), peroxidase (POD), and catalase (CAT), thus increasing the elimination rate of H2O2 in rice roots. Co-treatment using B and H2O2 does not increase root growth under Al toxicity conditions; it also improves pectin synthesis, enhances PME activity, and increases Al deposition in root cell walls. However, the co-treatment of B and H2O2 scavenger 4-hydroxy-TEMPO has an opposite effect. The above results indicate that applying B fertilizers in acidic soil can help decrease the side effects of Al toxicity on rice growth.

Unravelling calcium-alleviated aluminium toxicity in Arabidopsis thaliana: Insights into regulatory mechanisms using proteomics.

Aluminium (Al) toxicity is a major limiting factor for plant productivity in acidic soils. Calcium (Ca) is an essential element and participates in various physiological responses to environmental stress. Here, the aim of this work was to study the role of exogenous Ca in alleviating Al toxicity in Arabidopsis thaliana. For that we used the methods of physiology and proteomics. Results showed that Ca alleviated Al-induced growth inhibition and decreased Al accumulation. Proteomic analyses showed that 75 differentially expressed protein spots, including those related to organic acid metabolism, cell wall components, cellular transport, signal transduction and antioxidant activity, transcription and protein metabolism were identified during the response of Arabidopsis to Ca alleviated Al toxicity. Ca regulated tricarboxylic acid (TCA) cycle-related protein abundances and affected organic acid concentrations and related enzyme activities under Al stress. Vacuolar and mitochondrion adenosine triphosphate (ATP) synthase, and cell wall component-related proteins played important roles in Ca-alleviated Al toxicity. Ethylene-insensitive 3 (EIN3) participated in Ca-alleviated Al toxicity. Glutathione S-transferase (GST6) and glutathione S-transferase tau 19 (ATGSTU19) were associated with antioxidant activities induced by Ca under Al stress. Our results may contribute to an understanding of the functional mechanism by which Ca alleviates Al stress in plants. SIGNIFICANT: Our results elucidated how Ca alleviate the effects of Al toxicity on the inhibition of plant growth and Al accumulation in plants using the proteomics and physiological methods, which may contribute to a better understanding of the molecular mechanism of Ca alleviation Al stress in plants.

Up-regulation of SR-BI promotes progression and serves as a prognostic biomarker in clear cell renal cell carcinoma.

BACKGROUND: Scavenger receptor class B type I (SR-BI) has been reported to be involved in carcinogenesis of several human cancers. However, it is currently unknown whether SR-BI plays a role in clear cell renal cell carcinoma (ccRCC). Here, we aimed to evaluate a tumor promotive mechanism for SR-BI in ccRCC. METHODS: The expression of SR-BI was evaluated by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR), Western blot and immunohistochemistry (IHC) in ccRCC tissues and cell lines. Lipid droplets in ccRCC tissues and normal kidney tissues were examined by Oil Red O (ORO) and hematoxylin-eosin (HE) staining. The correlation between SR-BI mRNA levels and clinicopathological features was analyzed by Pearson's chi-square test or Fisher's exact test. Kaplan-Meier analysis and Cox model were used to evaluate the difference in progression-free survival (PFS) associated with expression of SR-BI. Inhibition of SR-BI was conducted by using small interfering RNA (siRNA). In vitro assays were performed to assess the impact of SR-BI knockdown on cell biological behaviors. High density lipoprotein (HDL)-cholesterol content in ccRCC cells and extracellular media was also measured after transfection with siRNA. RESULTS: The expression of SR-BI was markedly up-regulated in ccRCC tissues and tumor cell lines. ORO and HE staining revealed huge amounts of lipid droplets accumulation in ccRCC. Clinical analysis showed that over-expression of SR-BI was positively associated with tumor size, grade, distant metastasis and inversely correlated with PFS. Furthermore, SR-BI was proved to be an independent prognostic marker in ccRCC patients. The inhibition of SR-BI attenuated the tumorous behaviors of ccRCC cells, expression of metastasis and AKT pathway related proteins. The content of HDL-cholesterol was reduced in cells while increased in extracellular media after transfection with si-SR-BI. CONCLUSIONS: Our results demonstrate that SR-BI functions as an oncogene and promotes progression of ccRCC. SR-BI may serve as a potential prognostic biomarker and therapeutic target for ccRCC.

Glutathione homeostasis and Cd tolerance in the Arabidopsis sultr1;1-sultr1;2 double mutant with limiting sulfate supply.

KEY MESSAGE: Cadmium sensitivity in sultr1;1 - sultr1;2 double mutant with limiting sulfate supply is attributed to the decreased glutathione content that affected oxidative defense but not phytochelatins' synthesis. In plants, glutathione (GSH) homeostasis plays pivotal role in cadmium (Cd) detoxification. GSH is synthesized by sulfur (S) assimilation pathway. Many studies have tried to investigate the role of GSH homeostasis on Cd tolerance using mutants; however, most of them have focused on the last few steps of S assimilation. Until now, mutant evidence that explored the relationship between GSH homeostasis on Cd tolerance and S absorption is rare. To further reveal the role of GSH homeostasis on Cd stress, the wild-type and a sultr1;1-sultr1;2 double mutant which had a defect in two distinct high-affinity sulfate transporters were used in this study. Growth parameters, biochemical or zymological indexes and S assimilation-related genes' expression were compared between the mutant and wild-type Arabidopsis plants. It was found that the mutations of SULTR1;1 and SULTR1;2 did not affect Cd accumulation. Compared to the wild-type, the double mutant was more sensitive to Cd under limited sulfate supply and suffered from stronger oxidative damage. More importantly, under the same condition, lower capacity of S assimilation resulted in decreased GSH content in mutant. Faced to the limited GSH accumulation, mutant seedlings consumed a large majority of GSH in pool for the synthesis of phytochelatins rather than participating in the antioxidative defense. Therefore, homeostasis of GSH, imbalance between antioxidative defense and severe oxidative damage led to hypersensitivity of double mutant to Cd under limited sulfate supply.

[Paeonol affects proliferation activity of rat vasular endothelial cells induced by lipopolysaccharide and co-cultured with smooth muscle cells via inhibiting pathway of PI3K/AKT-NF-κB signaling].

This paper was aimed to observe the anti-atheroslerosis effect of paeonol (Pae) on the activation of PI3K/AKT-NF-κB and the proliferation activity of rat vasular endothelial cells induced by lipopolysaccharide (LPS) and co-cultured with smooth muscle cells. Primary rat vascular endothelial cells (VECs) and rat vascular smooth cells (VSMCs) were cultured by predigesting and adhering tissue blocks. The VEC-VSMC co-culture model was established by Transwell chamber. LPS (100 µg•L ⁻¹, 7 h) was used to induce VEC injury. MTT assay were used to determine the VEC proliferation activity. Western blot was used to detect PI3K/AKT and NF-κB's signaling pathways related protein expressions. The concentration of LPS-induced VECs injury was 100 µg•L ⁻¹, and the time was 7 h. After the intervention on the above cell model for 24 h, paeonol (15, 30, 60 µmol•L ⁻¹) could effectively inhibit LPS-induced VECs injury, block PI3K/AKT-NF-κB signal transduction pathway thereby significantly affecting the proliferation of LPS-induced VECs co-cultured with SMCs. The anti-atherosclerosis mechanism of paeonol may be related to the reducing the inhibitory effect of the signaling pathway associated proteins of VEC PI3K/AKT and NF-κB, thereby increasing the VEC livability under co-culture.

Hydrogen sulphide improves adaptation of Zea mays seedlings to iron deficiency.

Hydrogen sulphide (H2S) is emerging as a potential molecule involved in physiological regulation in plants. However, whether H2S regulates iron-shortage responses in plants is largely unknown. Here, the role of H2S in modulating iron availability in maize (Zea mays L. cv Canner) seedlings grown in iron-deficient culture solution is reported. The main results are as follows: Firstly, NaHS, a donor of H2S, completely prevented leaf interveinal chlorosis in maize seedlings grown in iron-deficient culture solution. Secondly, electron micrographs of mesophyll cells from iron-deficient maize seedlings revealed plastids with few photosynthetic lamellae and rudimentary grana. On the contrary, mesophyll chloroplasts appeared completely developed in H2S-treated maize seedlings. Thirdly, H2S treatment increased iron accumulation in maize seedlings by changing the expression levels of iron homeostasis- and sulphur metabolism-related genes. Fourthly, phytosiderophore (PS) accumulation and secretion were enhanced by H2S treatment in seedlings grown in iron-deficient solution. Indeed, the gene expression of ferric-phytosiderophore transporter (ZmYS1) was specifically induced by iron deficiency in maize leaves and roots, whereas their abundance was decreased by NaHS treatment. Lastly, H2S significantly enhanced photosynthesis through promoting the protein expression of ribulose-1,5-bisphosphate carboxylase large subunit (RuBISCO LSU) and phosphoenolpyruvate carboxylase (PEPC) and the expression of genes encoding RuBISCO large subunit (RBCL), small subunit (RBCS), D1 protein (psbA), and PEPC in maize seedlings grown in iron-deficient solution. These results indicate that H2S is closely related to iron uptake, transport, and accumulation, and consequently increases chlorophyll biosynthesis, chloroplast development, and photosynthesis in plants.

Nitric oxide ameliorates zinc oxide nanoparticles-induced phytotoxicity in rice seedlings.

Nitric oxide (NO) has been found to function in enhancing plant tolerance to various environmental stresses. However, role of NO in relieving zinc oxide nanoparticles (ZnO NPs)-induced phytotoxicity remains unknown. Here, sodium nitroprusside (SNP, a NO donor) was used to investigate the possible roles and the regulatory mechanisms of NO in counteracting ZnO NPs toxicity in rice seedlings. Our results showed that 10 µM SNP significantly inhibited the appearance of ZnO NP toxicity symptoms. SNP addition significantly reduced Zn accumulation, reactive oxygen species production and lipid peroxidation caused by ZnO NPs. The protective role of SNP in reducing ZnO NPs-induced oxidative damage is closely related to NO-mediated antioxidant system. A decrease in superoxide dismutase activity, as well as an increase in reduced glutathione content and peroxidase, catalase and ascorbate peroxidase activity was observed under SNP and ZnO NPs combined treatments, compared to ZnO NPs treatment alone. The relative transcript abundance of corresponding antioxidant genes exhibited a similar change. The role of NO in enhancing ZnO NPs tolerance was further confirmed by genetic analysis using a NO excess mutant (noe1) and an OsNOA1-silenced plant (noa1) of rice. Together, this study provides the first evidence indicating that NO functions in ameliorating ZnO NPs-induced phytotoxicity.

Comparative proteomics reveal the impact of OmcA/MtrC deletion on Shewanella oneidensis MR-1 in response to hexavalent chromium exposure.

Hexavalent chromium [Cr(VI)] is a priority pollutant causing serious environmental issues. Microbial reduction provides an alternative strategy for Cr(VI) remediation. The dissimilatory metal-reducing bacterium, Shewanella oneidensis MR-1, was employed to study Cr(VI) reduction and toxicity in this work. To understand the effect of membrane cytochromes on Cr(VI) response, a comparative protein profile analysis from S. oneidensis MR-1 wild type and its mutant of deleting OmcA and MtrC (△omcA/mtrC) was conducted using two-dimensional electrophoresis (2-DE) technology. The 2-DE patterns were compared, and the proteins with abundant changes of up to twofold in the Cr(VI) treatment were detected. Using mass spectrometry, 38 and 45 differentially abundant proteins were identified in the wild type and the mutant, respectively. Among them, 25 proteins were shared by the two strains. The biological functions of these identified proteins were analyzed. Results showed that Cr(VI) exposure decreased the abundance of proteins involved in transcription, translation, pyruvate metabolism, energy production, and function of cellular membrane in both strains. There were also significant differences in protein expressions between the two strains under Cr(VI) treatment. Our results suggest that OmcA/MtrC deletion might result in the Cr(VI) toxicity to outer membrane and decrease assimilation of lactate, vitamin B12, and cystine. When carbohydrate metabolism was inhibited by Cr(VI), leucine and sulfur metabolism may act as the important compensatory mechanisms in the mutant. Furthermore, the mutant may regulate electron transfer in the inner membrane and periplasm to compensate for the deletion of OmcA and MtrC in Cr(VI) reduction.

Nitric oxide mediates root K+/Na+ balance in a mangrove plant, Kandelia obovata, by enhancing the expression of AKT1-type K+ channel and Na+/H+ antiporter under high salinity.

It is well known that nitric oxide (NO) enhances salt tolerance of glycophytes. However, the effect of NO on modulating ionic balance in halophytes is not very clear. This study focuses on the role of NO in mediating K(+)/Na(+) balance in a mangrove species, Kandelia obovata Sheue, Liu and Yong. We first analyzed the effects of sodium nitroprusside (SNP), an NO donor, on ion content and ion flux in the roots of K. obovata under high salinity. The results showed that 100 µM SNP significantly increased K(+) content and Na(+) efflux, but decreased Na(+) content and K(+) efflux. These effects of NO were reversed by specific NO synthesis inhibitor and scavenger, which confirmed the role of NO in retaining K(+) and reducing Na(+) in K. obovata roots. Using western-blot analysis, we found that NO increased the protein expression of plasma membrane (PM) H(+)-ATPase and vacuolar Na(+)/H(+) antiporter, which were crucial proteins for ionic balance. To further clarify the molecular mechanism of NO-modulated K(+)/Na(+) balance, partial cDNA fragments of inward-rectifying K(+) channel, PM Na(+)/H(+) antiporter, PM H(+)-ATPase, vacuolar Na(+)/H(+) antiporter and vacuolar H(+)-ATPase subunit c were isolated. Results of quantitative real-time PCR showed that NO increased the relative expression levels of these genes, while this increase was blocked by NO synthesis inhibitors and scavenger. Above results indicate that NO greatly contribute to K(+)/Na(+) balance in high salinity-treated K. obovata roots, by activating AKT1-type K(+) channel and Na(+)/H(+) antiporter, which are the critical components in K(+)/Na(+) transport system.

Roles of fibroblast growth factor-inducible 14 in hepatocellular carcinoma.

The prognostic value of the fibroblast growth factor-inducible 14 (Fn14) expression in hepatocellular carcinoma (HCC) is unknown. Real-time PCR (RT-PCR), western blot assays and immunohistochemistry analysis were here performed in order to compare Fn14 expressions in paired liver samples of HCC and normal liver tissue. Most of the tumor tissues expressed significantly higher levels of Fn14 compared to adjacent non-tumor tissues, with Fn14High accounting for 54.6% (142/260) of all patients. The Pearson χ(2) test indicated that Fn14 expression was closely associated with serum alpha fetal protein (AFP) (P=0.002) and tumor number (p=0.019). Univariate and multivariate analyses revealed that along with tumor diameter and portal vein tumor thrombosis (PVTT ) type, Fn14 was an independent prognostic factor for both overall survival (OS) (HR=1.398, p=0.008) and recurrence (HR=1.541, p=0.001) rates. Fn14 overexpression HCC correlated with poor surgical outcome, and this molecule may be a candidate biomarker for prognosis as well as a target for therapy.