scholarly journals Differential Involvement of Histidine Kinase Receptors in Pseudohyphal Development, Stress Adaptation, and Drug Sensitivity of the Opportunistic Yeast Candida lusitaniae

2007 ◽  
Vol 6 (10) ◽  
pp. 1782-1794 ◽  
Author(s):  
Florence Chapeland-Leclerc ◽  
Paméla Paccallet ◽  
Gwenaël Ruprich-Robert ◽  
David Reboutier ◽  
Christiane Chastin ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Histidine Kinase ◽  
High Sensitivity ◽  
Triple Mutant ◽  
Mating Ability ◽  
Reverse Transcription Pcr ◽  
Moderate Sensitivity ◽  
Candida Lusitaniae ◽  
High Level

ABSTRACT Fungal histidine kinase receptors (HKRs) sense and transduce many extracellular signals. We investigated the role of HKRs in morphogenetic transition, osmotolerance, oxidative stress response, and mating ability in the opportunistic yeast Candida lusitaniae. We isolated three genes, SLN1, NIK1, and CHK1, potentially encoding HKRs of classes VI, III, and X, respectively. These genes were disrupted by a transformation system based upon the “URA3 blaster” strategy. Functional analysis of disruptants was undertaken, except for the sln1 nik1 double mutant and the sln1 nik1 chk1 triple mutant, which are not viable in C. lusitaniae. The sln1 mutant revealed a high sensitivity to oxidative stress, whereas both the nik1 and chk1 mutants exhibited a more moderate sensitivity to peroxide. We also showed that the NIK1 gene was implicated in phenylpyrrole and dicarboximide compound susceptibility while HKRs seem not to be involved in resistance toward antifungals of clinical relevance. Concerning mating ability, all disruptants were still able to reproduce sexually in vitro in unilateral or bilateral crosses. The most important result of this study was that the sln1 mutant displayed a global defect of pseudohyphal differentiation, especially in high-osmolarity and oxidative-stress conditions. Thus, the SLN1 gene could be crucial for the C. lusitaniae yeast-to-pseudohypha morphogenetic transition. This implication is strengthened by a high level of SLN1 mRNAs revealed by semiquantitative reverse transcription-PCR when the yeast develops pseudohyphae. Our findings highlight a differential contribution of the three HKRs in osmotic and oxidant adaptation during the morphological transition in C. lusitaniae.

scholarly journals Contributions of the Response Regulators Ssk1p and Skn7p in the Pseudohyphal Development, Stress Adaptation, and Drug Sensitivity of the Opportunistic Yeast Candida lusitaniae

2008 ◽  
Vol 7 (6) ◽  
pp. 1071-1074 ◽  
Author(s):  
Gwenaël Ruprich-Robert ◽  
Florence Chapeland-Leclerc ◽  
Stéphanie Boisnard ◽  
Martine Florent ◽  
Gaël Bories ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Functional Analysis ◽  
Histidine Kinase ◽  
Drug Sensitivity ◽  
Stress Adaptation ◽  
Response Regulators ◽  
Candida Lusitaniae

ABSTRACT We recently characterized the histidine kinase receptor genes of Candida lusitaniae. For the present study, we have further investigated the role of SSK1 and SKN7, encoding response regulators. The results of functional analysis of mutants indicated that Ssk1p is involved in osmotolerance and pseudohyphal development, whereas Skn7p appears crucial for oxidative stress adaptation.

scholarly journals DDB2, an Essential Mediator of Premature Senescence

2010 ◽  
Vol 30 (11) ◽  
pp. 2681-2692 ◽  
Author(s):  
Nilotpal Roy ◽  
Tanya Stoyanova ◽  
Carmen Dominguez-Brauer ◽  
Hyun Jung Park ◽  
Srilata Bagchi ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Dna Damage ◽  
Excision Repair ◽  
Culture Shock ◽  
Premature Senescence ◽  
Antioxidant Genes ◽  
Repair Protein ◽  
High Level

ABSTRACT Reactive oxygen species (ROS) is critical for premature senescence, a process significant in tumor suppression and cancer therapy. Here, we reveal a novel function of the nucleotide excision repair protein DDB2 in the accumulation of ROS in a manner that is essential for premature senescence. DDB2-deficient cells fail to undergo premature senescence induced by culture shock, exogenous oxidative stress, oncogenic stress, or DNA damage. These cells do not accumulate ROS following DNA damage. The lack of ROS accumulation in DDB2 deficiency results from high-level expression of the antioxidant genes in vitro and in vivo. DDB2 represses antioxidant genes by recruiting Cul4A and Suv39h and by increasing histone-H3K9 trimethylation. Moreover, expression of DDB2 also is induced by ROS. Together, our results show that, upon oxidative stress, DDB2 functions in a positive feedback loop by repressing the antioxidant genes to cause persistent accumulation of ROS and induce premature senescence.

scholarly journals After In Vitro Digestion, Jackfruit Flake Affords Protection against Acrylamide-Induced Oxidative Damage

Molecules ◽  
2019 ◽  
Vol 24 (18) ◽  
pp. 3322 ◽  
Author(s):  
Daofeng Qu ◽  
Chu Liu ◽  
Mengxue Jiang ◽  
Lifang Feng ◽  
Yuewen Chen ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Oxidative Damage ◽  
High Performance ◽  
In Vitro Digestion ◽  
Protective Effects ◽  
Physical Damage ◽  
Before And After ◽  
High Content Analysis ◽  
High Level

Some studies have demonstrated that acrylamide (AA) was correlated with oxidative stress, resulting in physical damage. The jackfruit flake was an immature pulp that contained a high level of antioxidant activity. This study aimed to assess the defensive efficacy of jackfruit flake in AA-induced oxidative stress before and after simulated gastrointestinal digestion. Our results indicate that the total polyphenol content of Jackfruit flake digest (Digestive products of jackfruit flake after gastrointestinal, JFG) was diminished; however, JFG had raised the relative antioxidant capacity compared to Jackfruit flake extract (JFE). Additionally, the results of High Performance Liquid Chromatography-Mass Spectrometry (HPLC-MS) implied that a proportion of compounds were degraded/converted into other unknown and/or undetected metabolites. Further, by high content analysis (HCA) techniques, JFG markedly reduced cytotoxicity and excessive production of reactive oxygen species (ROS) in cells, thereby alleviating mitochondrial disorders. In this study, it may be converted active compounds after digestion that had preferable protective effects against AA-induced oxidative damage.

scholarly journals In Vivo and In Vitro Evaluation of Urinary Biomarkers in Ischemia/Reperfusion-Induced Kidney Injury

2021 ◽  
Vol 22 (21) ◽  
pp. 11448
Author(s):  
Keiko Hosohata ◽  
Denan Jin ◽  
Shinji Takai
Keyword(s):  
Oxidative Stress ◽  
Ischemia Reperfusion ◽  
Kidney Injury ◽  
Experimental Models ◽  
Left Renal Artery ◽  
Tubular Injury ◽  
Renal Tubular ◽  
High Level

Oxidative stress plays an important role in the pathophysiology of acute kidney injury (AKI). Previously, we reported that vanin-1, which is involved in oxidative stress, is associated with renal tubular injury. This study was aimed to determine whether urinary vanin-1 is a biomarker for the early diagnosis of AKI in two experimental models: in vivo and in vitro. In a rat model of AKI, ischemic AKI was induced in uninephrectomized rats by clamping the left renal artery for 45 min and then reperfusing the kidney. On Day 1 after renal ischemia/reperfusion (I/R), serum creatinine (SCr) in I/R rats was higher than in sham-operated rats, but this did not reach significance. Urinary N-acetyl-β-D-glucosaminidase (NAG) exhibited a significant increase but decreased on Day 2 in I/R rats. In contrast, urinary vanin-1 significantly increased on Day 1 and remained at a significant high level on Day 2 in I/R rats. Renal vanin-1 protein decreased on Days 1 and 3. In line with these findings, immunofluorescence staining demonstrated that vanin-1 was attenuated in the renal proximal tubules of I/R rats. Our in vitro results confirmed that the supernatant from HK-2 cells under hypoxia/reoxygenation included significantly higher levels of vanin-1 as well as KIM-1 and NGAL. In conclusion, our results suggest that urinary vanin-1 might be a potential novel biomarker of AKI induced by I/R.

scholarly journals In Vitro Evolution of Itraconazole Resistance in Aspergillus fumigatus Involves Multiple Mechanisms of Resistance

2004 ◽  
Vol 48 (11) ◽  
pp. 4405-4413 ◽  
Author(s):  
Márcia Eliana da Silva Ferreira ◽  
José Luiz Capellaro ◽  
Everaldo dos Reis Marques ◽  
Iran Malavazi ◽  
David Perlin ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Resistant Mutant ◽  
Marker Genes ◽  
Reverse Transcription Pcr ◽  
Selectable Marker Genes ◽  
Clinical Resistance ◽  
Mutant Strains ◽  
Drug Efflux Pumps ◽  
High Level

ABSTRACT We investigated the evolution of resistance to the antifungal drug itraconazole in replicate populations of Aspergillus fumigatus that were founded from a strain with a genotype of sensitivity to a single drug and then propagated under uniform conditions. For each population, conidia were serially transferred 10 times to agar medium either with or without itraconazole. After 10 transfers in medium supplemented with itraconazole, 10 itraconazole-resistant mutant strains were isolated from two populations. These mutant strains had different growth rates and different levels of itraconazole resistance. Analysis of the ergosterol contents of these mutants showed that they accumulate ergosterol when they are grown in the presence of itraconazole. The replacement of the CYP51A gene of the wild-type strain changed the susceptibility pattern of this strain to one of itraconazole resistance only when CYP51A genes with N22D and M220I mutations were used as selectable marker genes. Real-time quantitative reverse transcription-PCR was used to assess the levels of expression of the Afumdr1, Afumdr2, Afumdr3, Afumdr4, AtrF transporter, CYP51A, and CYP51B genes in these mutant strains. Most mutants showed either constitutive high-level expression or induction upon exposure of Afumdr3, Afumdr4, and AtrF to itraconazole. Our results suggest that overexpression of drug efflux pumps and/or selection of drug target site mutations are at least partially responsible for itraconazole resistance and could be considered mechanisms for the emergence of clinical resistance to this drug.

Redox-mediated interactions of VHb (Vitreoscilla haemoglobin) with OxyR: novel regulation of VHb biosynthesis under oxidative stress

2010 ◽  
Vol 426 (3) ◽  
pp. 271-280 ◽  
Author(s):  
Arvind Anand ◽  
Brian T. Duk ◽  
Sandeep Singh ◽  
Meltem Y. Akbas ◽  
Dale A. Webster ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Transcriptional Control ◽  
High Sensitivity ◽  
Reduced Form ◽  
Gene Encoding ◽  
Antioxidant Genes ◽  
E Coli ◽  
Hypoxic Conditions ◽  
Catalase Peroxidase

The bacterial haemoglobin from Vitreoscilla, VHb, displays several unusual properties that are unique among the globin family. When the gene encoding VHb, vgb, is expressed from its natural promoter in either Vitreoscilla or Escherichia coli, the level of VHb increases more than 50-fold under hypoxic conditions and decreases significantly during oxidative stress, suggesting similar functioning of the vgb promoter in both organisms. In the present study we show that expression of VHb in E. coli induced the antioxidant genes katG (catalase–peroxidase G) and sodA (superoxide dismutase A) and conferred significant protection from oxidative stress. In contrast, when vgb was expressed in an oxyR mutant of E. coli, VHb levels increased and the strain showed high sensitivity to oxidative stress without induction of antioxidant genes; this indicates the involvement of the oxidative stress regulator OxyR in mediating the protective effect of VHb under oxidative stress. A putative OxyR-binding site was identified within the vgb promoter and a gel-shift assay confirmed its interaction with oxidized OxyR, an interaction which was disrupted by the reduced form of the transcriptional activator Fnr (fumurate and nitrate reductase). This suggested that the redox state of OxyR and Fnr modulates their interaction with the vgb promoter. VHb associated with reduced OxyR in two-hybrid screen experiments and in vitro, converting it into an oxidized state in the presence of NADH, a condition where VHb is known to generate H2O2. These observations unveil a novel mechanism by which VHb may transmit signals to OxyR to autoregulate its own biosynthesis, simultaneously activating oxidative stress functions. The activation of OxyR via VHb, reported in the present paper for the first time, suggests the involvement of VHb in transcriptional control of many other genes as well.

scholarly journals Hyperinsulinemia contributes to impaired-glucose-tolerance-induced renal injury via mir-7977/SIRT3 signaling

2020 ◽  
Vol 11 ◽  
pp. 204062232091600 ◽  
Author(s):  
Zhongai Gao ◽  
Ziyan Wang ◽  
Hong Zhu ◽  
Xinxin Yuan ◽  
Mengdi Sun ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Glucose Tolerance ◽  
Impaired Glucose Tolerance ◽  
Renal Injury ◽  
Structural Damage ◽  
Cellular Response ◽  
Renal Tubules ◽  
Tubular Injury ◽  
High Level

Background: Increasing evidence indicates that impaired glucose tolerance (IGT) is independently associated with chronic kidney disease, but the characteristics and underlying mechanisms remain largely unknown. Methods: Here, the cross-sectional study was performed to study the characteristics of IGT-induced renal injury (IGT-RI). Furthermore, urine microRNA profile was evaluated and microRNAs involved in tubular injury were determined by in-vitro experiments. Results: It was found that 12.1% of IGT patients had microalbuminuria, which we termed “IGT-RI.” Overall, 100% of patients with IGT-RI exhibited reabsorption dysfunction and 58.3% had structural damage in the renal tubules. Two-hour postprandial insulin, retinol-binding protein, and N-acetyl-β-glucosaminidase were significantly associated with microalbuminuria and they were independent risk factors for IGT-RI. The expression of mir-7977 was altered in IGT-RI patients and may be involved in cellular response to oxidative stress. In proximal tubule epithelial cells in vitro, a high level of insulin increased the expression of mir-7977 and decreased that of sirtuin 3 (SIRT3), leading to oxidative stress. Overexpression of mir-7977 further decreased SIRT3 expression, whereas inhibition of mir-7977 had the opposite effect. Furthermore, mir-7977 can bind to the 3′-untranslated region of SIRT3 mRNA and inhibit its expression. Moreover, inhibition of SIRT3 reduced the expression of cubilin and the endocytosis of albumin. Conclusions: In conclusion, IGT-RI mainly manifests as tubular injury, especially reabsorption dysfunction. Compensatory hyperinsulinemia may be involved. A high level of insulin can activate mir-7977/SIRT3 signaling, resulting in tubular injury by inducing oxidative stress as well as reabsorption dysfunction by inhibiting the expression of cubilin, ultimately contributing to IGT-RI.

scholarly journals Molecular Tools for the Detection of Nitrogen Cycling Archaea

Archaea ◽  
2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Antje Rusch
Keyword(s):  
Nitrogen Cycling ◽  
High Sensitivity ◽  
The Novel ◽  
Degenerate Primers ◽  
Culture Studies ◽  
Metabolic Genes ◽  
Nitrite Reductases ◽  
Genes Encoding ◽  
Moderate Sensitivity

Archaea are widespread in extreme and temperate environments, and cultured representatives cover a broad spectrum of metabolic capacities, which sets them up for potentially major roles in the biogeochemistry of their ecosystems. The detection, characterization, and quantification of archaeal functions in mixed communities require Archaea-specific primers or probes for the corresponding metabolic genes. Five pairs of degenerate primers were designed to target archaeal genes encoding key enzymes of nitrogen cycling: nitrite reductases NirA and NirB, nitrous oxide reductase (NosZ), nitrogenase reductase (NifH), and nitrate reductases NapA/NarG. Sensitivity towards their archaeal target gene, phylogenetic specificity, and gene specificity were evaluated in silico and in vitro. Owing to their moderate sensitivity/coverage, the novelnirB-targeted primers are suitable for pure culture studies only. ThenirA-targeted primers showed sufficient sensitivity and phylogenetic specificity, but poor gene specificity. The primers designed for amplification of archaealnosZperformed well in all 3 criteria; their discrimination against bacterial homologs appears to be weakened when Archaea are strongly outnumbered by bacteria in a mixed community. The novelnifH-targeted primers showed high sensitivity and gene specificity, but failed to discriminate against bacterial homologs. Despite limitations, 4 of the new primer pairs are suitable tools in several molecular methods applied in archaeal ecology.

scholarly journals In vitro susceptibility of duck, chicken, and pig erythrocyte lipids to peroxidation

2012 ◽  
Vol 47 (No. 10 - 11) ◽  
pp. 303-308 ◽  
Author(s):  
B. Gradinski-Vrbanac ◽  
Z. Stojevič ◽  
S. Milinkovič-Tur ◽  
T. Balenovič ◽  
J. Piršljin ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Reduced Glutathione ◽  
Thiobarbituric Acid ◽  
Thiobarbituric Acid Reactive Substances ◽  
Erythrocyte Suspension ◽  
In Vitro Susceptibility ◽  
Before And After ◽  
High Level ◽  
Erythrocyte Lipid

The susceptibility of erythrocyte lipid to in vitro peroxidation as measured by TBARS (thiobarbituric acid-reactive substances) and concentration of reduced glutathione (GSH) in whole blood and erythrocyte suspension before and after incubation with hydrogen peroxide was assessed in ducks, chickens and pigs. A high susceptibility of erythrocytes to peroxidation in vitro was observed in all animals tested, but this susceptibility was of different intensity. Pig erythrocytes exhibited the lowest resistance to oxidative stress in vitro as compared with that in ducks (P < 0.01) and chickens (P < 0.02). A high level of GSH in the erythrocytes of ducks and chickens offers higher resistance to oxidative stress in comparison with that in the pig erythrocytes.

scholarly journals Role of Beclin-1-Mediated Autophagy in the Survival of Pediatric Leukemia Cells

2016 ◽  
Vol 39 (5) ◽  
pp. 1827-1836 ◽  
Author(s):  
Xiaoli Wu ◽  
Xuefeng Feng ◽  
Xiaoqing Zhao ◽  
Futian Ma ◽  
Na Liu ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Survival ◽  
Marrow Cell ◽  
Beclin 1 ◽  
Luciferase Reporter ◽  
Pediatric Leukemia ◽  
Protein Levels ◽  
High Level

Background/Aims: Acute and chronic leukemia are severe malignant cancers worldwide, and can occur in pediatric patients. Since bone marrow cell transplantation is seriously limited by the availability of the immune-paired donor sources, the therapy for pediatric leukemia (PL) remains challenging. Autophagy is essential for the regulation of cell survival in the harsh environment. However, the role of autophagy in the survival of PL cells under the oxidative stress, e.g. chemotherapy, remain ill-defined. In the current study, we addressed these questions. Methods: We analyzed the effects of oxidative stress on the cell viability of PL cells in vitro, using a CCK-8 assay. We analyzed the effects of oxidative stress on the apoptosis and autophagy of PL cells. We analyzed the levels of Beclin-1 and microRNA-93 (miR-93) in PL cells. Prediction of binding between miR-93 and 3'-UTR of Beclin-1 mRNA was performed by a bioinformatics algorithm and confirmed by a dual luciferase reporter assay. The relationship between levels of miR-93 and patients' survival was analyzed in PL patients. Results: We found that oxidative stress dose-dependently increased autophagy in PL cells. While low-level oxidative stress did not increase apoptosis, high-level oxidative stress increased apoptosis, seemingly from failure of autophagy-mediated cell survival. High-level oxidative stress appeared to suppress the protein levels of an autophagy protein Beclin-1 in PL cells, possibly through induction of miR-93, which inhibited the translation of Beclin-1 mRNA via 3'-UTR binding. Conclusion: Beclin-1-mediated autophagy plays a key role in the survival of PL cells against oxidative stress. Induction of miR-93 may increase the sensitivity of PL cells to oxidative stress during chemotherapy to improve therapeutic outcome.

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