The malfunction of peroxisome has an impact on the oxidative stress sensitivity in Candida albicans

Potential biomarkers in hypoglycemic brain injury

Oxidative stress is a major underlying mechanism in hypoglycemic brain injury. Several oxidative stress-related proteins were identified through previous proteomics and literature review. The aim of the present study was to evaluate the potential of these proteins as biomarkers in hypoglycemic brain injury. Forty male Sprague Dawley rats were randomly and equally divided into four groups: control, acute hypoglycemia, hypoglycemia resuscitation 24 h, and hypoglycemia resuscitation 7 days. The hypoglycemic brain injury rat model was successfully constructed according to the Auer model. Real-time fluorescent quantitative polymerase chain reaction, western blot analysis, and immunohistochemical staining were used to quantify the expression of oxidative stress-related proteins. We also verified the expression level of selected protein in the brain samples of fatal insulin overdose cases. The expression of oxidative stress-related proteins PEX1/5/12 was down-regulated in hypoglycemic brain injury (P < 0.05), while the expressions of DJ-1 and NDRG1 were up-regulated (P < 0.05). Compared with the control group, the serum oxidative stress indexes SOD and MDA in the acute hypoglycemia group were significantly different (P < 0.01). The expressions of DJ-1 and NDRG1 in the hippocampus, cortex, and hypothalamus of rats were increased (P < 0.05). The expressions of DJ-1 and NDRG1 proteins in the cortex of the autopsy samples of insulin overdose were increased (P < 0.05). Oxidative stress-related proteins showed potential value as specific molecular markers in hypoglycemic brain injury, but further confirmatory studies are needed.

Dual transcriptome of Streptococcus mutans and Candida albicans interplay in biofilms

Objective

To assess the interactions between Streptococcus mutans and Candida albicans during cariogenic biofilm formation.

Methods

The S. mutans and C. albicans duo-species biofilms were formed in 1% sucrose to mimic the high caries risk challenges. The biofilm structure was assessed using two-photon laser confocal microscopy. The transcriptome of 48h-biofilms was assessed by RNA-Seq. The expression of S. mutans and C. albicans virulence genes was examined via real-time reverse transcription-polymerase chain reaction.

Results

The morphogenesis of C. albicans-S. mutans duo-species biofilms was significantly altered when comparing to S. mutans or C. albicans single-species biofilm. Duo-species biofilms exhibited unique expression profile with a large number of differentially expressed genes (DEGs), including a higher expression of S. mutans atpD (acid-adaptive), C. albicans CHT2 (fungal cell wall chitin remodeling), and C. albicans SOD3 (cytotoxic oxygen radical destroying) (p < 0.05). KEGG pathway analyses further revealed that the majority of the up-regulated DEGs are related to microbial metabolism. Furthermore, the expressions of S. mutans and C. albicans key virulence genes (gtfB, gtfC, gtfD, ECE1, HWP1, ERG4, CHT2) were associated with sugar availability-related and time-related dynamics.

Conclusion

Cross-kingdom interactions impact S. mutans-C. albicans biofilm formations and dynamic expressions of virulence genes.

A Proteomic Landscape of Candida albicans in the Stepwise Evolution to Fluconazole Resistance

As an opportunistic fungal pathogen, Candida albicans is a major cause of superficial and systemic infections in immunocompromised patients. The increasing rate of azole resistance in C. albicans has brought further challenges to clinical therapy. In this study, we collected five isogenic C. albicans strains recovered over discrete intervals from an HIV-infected patient who suffered 2-year recurrent oropharyngeal candidiasis. Azole resistance was known from the clinical history to have developed gradually in this patient, and this was confirmed by MIC assays of each strain. Proteomic techniques can be used to investigate more comprehensively how resistance develops in pathogenic fungi over time. Our study is the first to use tandem mass tag (TMT) labeling combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) technology to investigate the acquired resistance mechanisms of serial C. albicans isolates at the proteomic level. A total of 4,029 proteins have been identified, of which 3,766 have been quantified. Compared with Ca1, bioinformatics analysis showed that differentially expressed proteins were mainly associated with aspects such as the downregulation of glycolysis/gluconeogenesis, pyruvate metabolism, fatty acid degradation, and oxidative stress response proteins in all four subsequent strains but, remarkably, the activation of amino acid metabolism in Ca8 and Ca14 and increased protection against osmotic stress or excessive copper toxicity, upregulation of respiratory chain activity, and suppression of iron transport in Ca17. By tracing proteomic alterations in this set of isogenic resistance isolates, we acquire mechanistic insight into the steps involved in the acquisition of azole resistance in C. albicans.

Effects of pex1 disruption on wood lignin biodegradation, fruiting development and the utilization of carbon sources in the white-rot Agaricomycete Pleurotus ostreatus and non-wood decaying Coprinopsis cinerea

Peroxisomes are well-known organelles that are present in most eukaryotic organisms. Mutant phenotypes caused by the malfunction of peroxisomes have been shown in many fungi. However, these have never been investigated in Agaricomycetes, which include white-rot fungi that degrade wood lignin in nature almost exclusively and play an important role in the global carbon cycle. Based on the results of a forward genetics study to identify mutations causing defects in the ligninolytic activity of the white-rot Agaricomycete Pleurotus ostreatus, we report phenotypes of pex1 disruptants in P. ostreatus, which are defective in two major features of white-rot Agaricomycetes: lignin biodegradation and mushroom formation. Pex1 disruption was also shown to cause defects in the hyphal growth of P. ostreatus on certain sawdust and minimum media. We also demonstrated that pex1 is essential for fruiting initiation in the non-wood decaying Agaricomycete Coprinopsis cinerea. However, unlike P. ostreatus, significant defects in hyphal growth on the aforementioned agar medium were not observed in C. cinerea. This result, together with previous C. cinerea genetic studies, suggests that the regulation mechanisms for the utilization of carbon sources are altered during the evolution of Agaricomycetes or Agaricales.