New insights into molecular targets of salt tolerance in sorghum leaves elicited by ammonium nutrition.

This study investigated the proteome modulation and physiological responses of Sorghum bicolor plants grown in nutrient solutions containing nitrate (NO3-) or ammonium (NH4+) at 5.0 mM, and subjected to salinity with 75 mM NaCl for ten days. Salinity promoted significant reductions in leaf area, root and shoot dry mass of sorghum plants, regardless of nitrogen source; however, higher growth was observed in ammonium-grown plants. The better performance of ammonium-fed stressed plants was associated with low hydrogen peroxide accumulation, and improved CO2 assimilation and K+/Na+ homeostasis under salinity. Proteomic study revealed a nitrogen source-induced differential modulation in proteins related to photosynthesis/carbon metabolism, energy metabolism, response to stress and other cellular processes. Nitrate-fed plants induced thylakoidal electron transport chain proteins and structural and carbon assimilation enzymes, but these mechanisms seemed to be insufficient to mitigate salt damage in photosynthetic performance. In contrast, the greater tolerance to salinity of ammonium-grown plants may have arisen from: i.) de novo synthesis or upregulation of enzymes from photosynthetic/carbon metabolism, which resulted in better CO2 assimilation rates under NaCl-stress; ii.) activation of proteins involved in energy metabolism which made available energy for salt responses, most likely by proton pumps and Na+/H+ antiporters; and iii.) reprogramming of proteins involved in response to stress and other metabolic processes, constituting intricate pathways of salt responses. Overall, our findings not only provide new insights of molecular basis of salt tolerance in sorghum plants induced by ammonium nutrition, but also give new perspectives to develop biotechnological strategies to generate more salt-tolerant crops.

Proteins Involved in the Induction of Procoagulant Activity and Autoimmune Response in Patients With Primary Antiphospholipid Syndrome.

The aim of this study was to determine the plasma protein profile of patients with primary antiphospholipid syndrome (PAPS) compared to healthy controls and identify proteins that might be used in the evaluation, diagnosis, and prognosis of this condition. The sample consisted of 14 patients with PAPS and 17 sex- and age-matched controls. Plasma samples were submitted to proteomic analysis (albumin and immunoglobulin G depletion, concentration, digestion, and label-free data-independent mass spectrometry). The software ExpressionE was used to quantify intergroup differences in protein expression. The analysis yielded 65 plasma proteins of which 11 were differentially expressed (9 upregulated and 2 downregulated) in relation to controls. Four of these are known to play a role in pathophysiological mechanisms of thrombosis: fibrinogen α chain, fibrinogen α chain, apolipoprotein C-III, and α-1-glycoprotein-1. Our analysis revealed autoimmune response and the presence of proteins believed to be functionally involved in the induction of procoagulant activity in patients with PAPS. Further studies are necessary to confirm our findings and may eventually lead to the development of significantly more accurate diagnostic tools.

Differences in protein expression associated with ivermectin resistance in Caenorhabditis elegans.

The indiscriminate administration of synthetic anthelmintics such as ivermectin contributes to the selection of subpopulations capable of resisting the drugs' effects. To understand the mechanisms of ivermectin resistance in Caenorhabditis elegans, this study attempted to identify molecular targets. C. elegans lineages that were sensitive and resistant to ivermectin were used. Collected nematodes were added to an extraction buffer and macerated in liquid nitrogen for protein extraction. The extracted proteins were separated according to molecular weight by SDS-PAGE to verify their integrity. Subsequently, proteins from both lineages were separated using two-dimensional electrophoresis. The gels were analyzed and the relevant spots were excised and identified by mass spectrometry (NanoESI-Q-TOF and MASCOT®) and subsequently assessed by GO enrichment and STRING® analyses. The increased expression of proteins associated with high metabolic activity, such as ATP-2 and ENOL-1, which are responsible for ATP synthesis, was observed. Furthermore, proteins with involvement in mediating muscular function (MLC-1, ACT-1, and PDI-2), signaling (FAR-1 and FAR-2), and embryo development (VHA-2) were identified. Protein interaction analysis indicated that the majority of the identified proteins in the resistant lineages participated in the same reaction triggered by ivermectin.

Differences in protein expression associated with ivermectin resistance in Caenorhabditis elegans / Diferenças na expressão de proteínas associadas à resistência à ivermectina em Caenorhabditis elegans

Abstract The indiscriminate administration of synthetic anthelmintics such as ivermectin contributes to the selection of subpopulations capable of resisting the drugs' effects. To understand the mechanisms of ivermectin resistance in Caenorhabditis elegans, this study attempted to identify molecular targets. C. elegans lineages that were sensitive and resistant to ivermectin were used. Collected nematodes were added to an extraction buffer and macerated in liquid nitrogen for protein extraction. The extracted proteins were separated according to molecular weight by SDS-PAGE to verify their integrity. Subsequently, proteins from both lineages were separated using two-dimensional electrophoresis. The gels were analyzed and the relevant spots were excised and identified by mass spectrometry (NanoESI-Q-TOF and MASCOT®) and subsequently assessed by GO enrichment and STRING® analyses. The increased expression of proteins associated with high metabolic activity, such as ATP-2 and ENOL-1, which are responsible for ATP synthesis, was observed. Furthermore, proteins with involvement in mediating muscular function (MLC-1, ACT-1, and PDI-2), signaling (FAR-1 and FAR-2), and embryo development (VHA-2) were identified. Protein interaction analysis indicated that the majority of the identified proteins in the resistant lineages participated in the same reaction triggered by ivermectin.

Resumo A administração indiscriminada de anti-helmínticos sintéticos, como a ivermectina, contribui para a seleção de subpopulações capazes de resistir ao efeito das drogas. Para entender os mecanismos de resistência à ivermectina em Caenorhabditis elegans, este estudo visou identificar alvos moleculares. Portanto, linhagens de C. elegans sensíveis e resistentes à ivermectina foram utilizadas. Os nematóides coletados foram adicionados ao tampão de extração e macerados em nitrogênio líquido para obtenção das proteínas. As proteínas extraídas foram separadas por peso molecular em SDS-PAGE para verificar sua integridade. Posteriormente, as proteínas de ambas as linhagens foram separadas por eletroforese bidimensional. Os géis foram analisados, os spots relevantes foram excisados e identificados por espectrometria de massa (NanoESI-Q-TOF e MASCOT®), em seguida, analisados ​​em seus termos de GO e STRING®. A expressão aumentada de proteínas associadas à alta atividade metabólica, como as proteínas ATP-2 e ENOL-1, responsáveis ​​pela síntese de ATP, foi observada. Além disso, foram identificadas as proteínas responsáveis ​​pelo controle da função muscular (MLC-1, ACT-1 e PDI-2), sinalização (FAR-1 e FAR-2) e desenvolvimento embrionário (VHA-2). A análise das interações proteicas indicou que a maioria das proteínas identificadas na cepa resistente participa da mesma reação desencadeada pela ivermectina.

Neuropharmacological characterization of frutalin in mice: Evidence of an antidepressant-like effect mediated by the NMDA receptor/NO/cGMP pathway.

In this study we evaluated the effect of frutalin (FTL) on mouse behavior. Mice (n=6/group) were treated (i.p.) with FTL (0.25; 0.5 or 1mg/kg) or vehicle and submitted to several tests (hole-board/HBT, elevated plus maze/PMT, open field/OFT, tail suspension/TST, or forced swimming/FST). Yohimbine, ketamine, l-NAME, aminoguanidine, 7-NI, methylene blue, l-arginine or dl-serine was administered 30min before FTL (0.5mg/kg). To evaluate the subchronic effect, animals were injected with FTL or vehicle for 7days and submitted to the FST. Molecular docking was simulated using FTL against NOS and the NMDA receptor. No changes were observed in the HBT or the OFT. FTL (0.25mg/kg) increased the number of entries into enclosed arms in the PMT. FTL reduced immobility in the TST (0.25 and 0.5mg/kg) and the FST (0.25mg/kg; 0.5mg/kg). The effect of FTL was dependent on carbohydrate interaction and protein structure integrity and was reduced by ketamine, l-NAME, aminoguanidine, 7-NI and methylene blue, but not by l-arginine, yohimbine or dl-serine. The antidepressant-like effect remained after subchronic treatment. The molecular docking study revealed a strong interaction between FTL and NOS and NMDA. FTL was found to have an antidepressant-like effect mediated by the NMDA receptor/NO/cGMP pathway.

Action mechanism of naphthofuranquinones against fluconazole-resistant Candida tropicalis strains evidenced by proteomic analysis: The role of increased endogenous ROS.

The increased incidence of candidemia in terciary hospitals worldwide and the cross-resistance frequency require the new therapeutic strategies development. Recently, our research group demonstrated three semi-synthetic naphthofuranquinones (NFQs) with a significant antifungal activity in a fluconazole-resistant (FLC) C. tropicalis strain. The current study aimed to investigate the action's preliminary mechanisms of NFQs by several standardized methods such as proteomic and flow cytometry analyzes, comet assay, immunohistochemistry and confocal microscopy evaluation. Our data showed C. tropicalis 24 h treated with all NFQs induced an expression's increase of proteins involved in the metabolic response to stress, energy metabolism, glycolysis, nucleosome assembly and translation process. Some aspects of proteomic analysis are in consonance with our flow cytometry analysis which indicated an augmentation of intracellular ROS, mitochondrial dysfunction and DNA strand breaks (neutral comet assay and γ-H2AX detection). In conclusion, our data highlights the great contribution of ROS as a key event, probably not the one, associated to anti-candida properties of studied NFQs.

Frutapin, a lectin from Artocarpus incisa (breadfruit): cloning, expression and molecular insights.

Artocarpus incisa (breadfruit) seeds contain three different lectins (Frutalin, Frutapin (FTP) and Frutackin) with distinct carbohydrate specificities. The most abundant lectin is Frutalin, an α-D-galactose-specific carbohydrate-binding glycoprotein with antitumour properties and potential for tumour biomarker discovery as already reported. FTP is the second most abundant, but proved difficult to purify with very low yields and contamination with Frutalin frustrating its characterization. Here, we report for the first time high-level production and isolation of biologically active recombinant FTP in Escherichia coli BL21, optimizing conditions with the best set yielding >40 mg/l culture of soluble active FTP. The minimal concentration for agglutination of red blood cells was 62.5 µg/ml of FTP, a process effectively inhibited by mannose. Apo-FTP, FTP-mannose and FTP-glucose crystals were obtained, and they diffracted X-rays to a resolution of 1.58 (P212121), 1.70 (P3121) and 1.60 (P3121) Å respectively. The best solution showed four monomers per asymmetric unit. Molecular dynamics (MD) simulation suggested that FTP displays higher affinity for mannose than glucose. Cell studies revealed that FTP was non-cytotoxic to cultured mouse fibroblast 3T3 cells below 0.5 mg/ml and was also capable of stimulating cell migration at 50 µg/ml. In conclusion, our optimized expression system allowed high amounts of correctly folded soluble FTP to be isolated. This recombinant bioactive lectin will now be tested in future studies for therapeutic potential; for example in wound healing and tissue regeneration.

Label-Free Proteome Analysis of Plasma from Patients with Breast Cancer: Stage-Specific Protein Expression.

Breast cancer is one of the most commonly diagnosed types of cancer among women. Breast cancer mortality rates remain high probably because its diagnosis is hampered by inaccurate detection methods. Since changes in protein expression as well as modifications in protein glycosylation have been frequently reported in cancer development, the aim of this work was to study the differential expression as well as modifications of glycosylation of proteins from plasma of women with breast cancer at different stages of disease (n = 30) compared to healthy women (n = 10). A proteomics approach was used that depleted albumin and IgG from plasma followed by glycoprotein enrichment using immobilized Moraceae lectin (frutalin)-affinity chromatography and data-independent label-free mass spectrometric analysis. Data are available via ProteomeXchange with identifier PXD003106. As result, 57,016 peptides and 4,175 proteins among all samples were identified. From this, 40 proteins present in unbound (PI-proteins that did not interact with lectin) and bound (PII-proteins that interacted with lectin) fractions were differentially expressed. High levels of apolipoprotein A-II were detected here that were elevated significantly in the early and advanced stages of the disease. Apolipoprotein C-III was detected in both fractions, and its level was increased slightly in the PI fraction of patients with early-stage breast cancer and expressed at higher levels in the PII fraction of patients with early and intermediate stages. Clusterin was present at higher levels in both fractions of patients with early and intermediate stages of breast cancer. Our findings reveal a correlation between alterations in protein glycosylation, lipid metabolism, and the progression of breast cancer.

A panel of glycoproteins as candidate biomarkers for early diagnosis and treatment evaluation of B-cell acute lymphoblastic leukemia.

BACKGROUND: Acute lymphoblastic leukemia is the most common malignant cancer in childhood. The signs and symptoms of childhood cancer are difficult to recognize, as it is not the first diagnosis to be considered for nonspecific complaints, leading to potential uncertainty in diagnosis. The aim of this study was to perform proteomic analysis of serum from pediatric patients with B-cell acute lymphoblastic leukemia (B-ALL) to identify candidate biomarker proteins, for use in early diagnosis and evaluation of treatment. METHODS: Serum samples were obtained from ten patients at the time of diagnosis (B-ALL group) and after induction therapy (AIT group). Sera from healthy children were used as controls (Control group). The samples were subjected to immunodepletion, affinity chromatography with α-d-galactose-binding lectin (from Artocarpus incisa seeds) immobilized on a Sepharose(TM) 4B gel, concentration, and digestion for subsequent analysis with nano-UPLC tandem nano-ESI-MS(E). The program Expression (E) was used to quantify differences in protein expression between groups. RESULTS: A total of 96 proteins were identified. Leucine-rich alpha-2-glycoprotein 1 (LRG1), Clusterin (CLU), thrombin (F2), heparin cofactor II (SERPIND1), alpha-2-macroglobulin (A2M), alpha-2-antiplasmin (SERPINF2), Alpha-1 antitrypsin (SERPINA1), Complement factor B (CFB) and Complement C3 (C3) were identified as candidate biomarkers for early diagnosis of B-ALL, as they were upregulated in the B-ALL group relative to the control and AIT groups. Expression levels of the candidate biomarkers did not differ significantly between the AIT and control groups, providing further evidence that the candidate biomarkers are present only in the disease state, as all patients achieved complete remission after treatment. CONCLUSION: A panel of protein biomarker candidates has been developed for pre-diagnosis of B-ALL and also provided information that would indicate a favorable response to treatment after induction therapy.

Synergistic effect of the flavonoid catechin, quercetin, or epigallocatechin gallate with fluconazole induces apoptosis in Candida tropicalis resistant to fluconazole.

Flavonoids are a class of phenolic compounds commonly found in fruits, vegetables, grains, flowers, tea, and wine. They differ in their chemical structures and characteristics. Such compounds show various biological functions and have antioxidant, antimicrobial, anti-inflammatory, and antiapoptotic properties. The aim of this study was to evaluate the in vitro interactions of flavonoids with fluconazole against Candida tropicalis strains resistant to fluconazole, investigating the mechanism of synergism. Three combinations formed by the flavonoids (+)-catechin hydrated, hydrated quercetin, and (-)-epigallocatechin gallate at a fixed concentration with fluconazole were tested. Flavonoids alone had no antifungal activity within the concentration range tested, but when they were used as a cotreatment with fluconazole, there was significant synergistic activity. From this result, we set out to evaluate the possible mechanisms of cell death involved in this synergism. Isolated flavonoids did not induce morphological changes or changes in membrane integrity in the strains tested, but when they were used as a cotreatment with fluconazole, these changes were quite significant. When evaluating mitochondrial damage and the production of reactive oxygen species (ROS) only in the cotreatment, changes were observed. Flavonoids combined with fluconazole were shown to cause a significant increase in the rate of damage and the frequency of DNA damage in the tested strains. The cotreatment also induced an increase in the externalization of phosphatidylserine, an important marker of early apoptosis. It is concluded that flavonoids, when combined with fluconazole, show activity against strains of C. tropicalis resistant to fluconazole, promoting apoptosis by exposure of phosphatidylserine in the plasma membrane and morphological changes, mitochondrial depolarization, intracellular accumulation of ROS, condensation, and DNA fragmentation.

Expression and efficient secretion of a functional chitinase from Chromobacterium violaceum in Escherichia coli.

BACKGROUND: Chromobacterium violaceum is a free-living ß-proteobacterium found in tropical and subtropical regions. The genomic sequencing of C. violaceum ATCC 12472 has revealed many genes that underpin its adaptability to diverse ecosystems. Moreover, C. violaceum genes with potential applications in industry, medicine and agriculture have also been identified, such as those encoding chitinases. However, none of the chitinase genes of the ATCC 12472 strain have been subjected to experimental validation. Chitinases (EC 3.2.1.14) hydrolyze the ß-(1,4) linkages in chitin, an abundant biopolymer found in arthropods, mollusks and fungi. These enzymes are of great biotechnological interest as potential biocontrol agents against pests and pathogens. This work aimed to experimentally validate one of the chitinases from C. violaceum. RESULTS: The open reading frame (ORF) CV2935 of C. violaceum ATCC 12472 encodes a protein (439 residues) that is composed of a signal peptide, a chitin-binding domain, a linker region, and a C-terminal catalytic domain belonging to family 18 of the glycoside hydrolases. The ORF was amplified by PCR and cloned into the expression vector pET303/CT-His. High levels of chitinolytic activity were detected in the cell-free culture supernatant of E. coli BL21(DE3) cells harboring the recombinant plasmid and induced with IPTG. The secreted recombinant protein was purified by affinity chromatography on a chitin matrix and showed an apparent molecular mass of 43.8 kDa, as estimated by denaturing polyacrylamide gel electrophoresis. N-terminal sequencing confirmed the proper removal of the native signal peptide during the secretion of the recombinant product. The enzyme was able to hydrolyze colloidal chitin and the synthetic substrates p-nitrophenyl-ß-D-N,N'-diacetylchitobiose and p-nitrophenyl-ß-D-N,N',N"-triacetylchitotriose. The optimum pH for its activity was 5.0, and the enzyme retained ~32% of its activity when heated to 60°C for 30 min. CONCLUSIONS: A C. violaceum chitinase was expressed in E. coli and purified by affinity chromatography on a chitin matrix. The secretion of the recombinant protein into the culture medium was directed by its native signal peptide. The mature enzyme was able to hydrolyze colloidal chitin and synthetic substrates. This newly identified signal peptide is a promising secretion factor that should be further investigated in future studies, aiming to demonstrate its usefulness as an alternative tool for the extracellular production of recombinant proteins in E. coli.

Synergistic effects of amiodarone and fluconazole on Candida tropicalis resistant to fluconazole.

There have recently been significant increases in the prevalence of systemic invasive fungal infections. However, the number of antifungal drugs on the market is limited in comparison to the number of available antibacterial drugs. This fact, coupled with the increased frequency of cross-resistance, makes it necessary to develop new therapeutic strategies. Combination drug therapies have become one of the most widely used and effective strategies to alleviate this problem. Amiodarone (AMD) is classically used for the treatment of atrial fibrillation and is the drug of choice for patients with arrhythmia. Recent studies have shown broad antifungal activity of the drug when administered in combination with fluconazole (FLC). In the present study, we induced resistance to fluconazole in six strains of Candida tropicalis and evaluated potential synergism between fluconazole and amiodarone. The evaluation of drug interaction was determined by calculating the fractional inhibitory concentration and by performing flow cytometry. We conclude that amiodarone, when administered in combination with fluconazole, exhibits activity against strains of C. tropicalis that are resistant to fluconazole, which most likely occurs via changes in the integrity of the yeast cell membrane and the generation of oxidative stress, mitochondrial dysfunction, and DNA damage that could lead to cell death by apoptosis.