The glyoxylate cycle plays an essential role for anaplerosis of oxaloacetate during growth of microorganisms on carbon sources such as acetate or fatty acids and has been shown to contribute to virulence of several pathogens. Here, we investigated the transcriptional and post‐translational regulation of the glyoxylate cycle key enzyme isocitrate lyase (PbICL) in the human pathogenic fungus Paracoccidioides brasiliensis. Although sequence analyses on fungal isocitrate lyases revealed a high phylogenetic conservation, their regulation seems to differ significantly. Closely related Aspergillus species regulate the glyoxylate cycle at the transcriptional level, whereas Pbicl was constitutively expressed in yeast cells. However, only low PbICL activity was detected when cells were grown in the presence of glucose. Two‐dimensional gel analyses with subsequent antibody hybridization revealed constitutive production of PbICL, but low PbICL activity on glucose coincided with extensive protein phosphorylation. Since an in vitro dephosphorylation of PbICL from glucose grown cells strongly increased ICL activity and resembled the phosphorylation pattern of highly active acetate grown cells, post‐translational modification seems the main mechanism regulating PbICL activity in yeast cells. In agreement, a transfer of yeast cells from glucose to acetate medium increased PbICL activity without requirement of de novo protein synthesis. Thus, inactivation of PbICL by phosphorylation is reversible, denoting a new strategy for the rapid adaptation to changing environmental conditions.

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La ciencia para la sustentabilidad plantea incluir en investigaciones y acciones los conocimientos y técnicas desarrollados por diversos sectores de la sociedad. Esta propuesta reconoce que la complejidad de los problemas ambientales rebasa los enfoques y ritmos de la investigación científica predominante y brinda la posibilidad de acortar tiempos para la acción, aprovechando integralmente la experiencia humana. Presentamos un panorama de nuestro trabajo en: 1) investigación participativa, 2) procesos educativos para la participación y 3) procesos institucionales de comunicación y participación. Se abordan estudios socioecológicos participativos que involucran innovación tecnológica e intercambios de experiencias técnicas y organizativas para atender problemas ambientales en el

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BackgroundThe role of oxidative stress in schizophrenia has been demonstrated, particularly in subjects with treatment-resistant schizophrenia (TRS). In such patients, the decreased levels of antioxidants in conjunction with the increased generation of reactive oxygen species in the brain exposes the neurons to a higher risk of damage.Methods and findingsWe evaluated the association of deletion polymorphisms of two genes of the antioxidant Glutathione S-Transferase family, GSTT1 and GSTM1, with susceptibility to TRS. A total of 54 TRS patients (mean age 38.7 years) and 78 healthy control subjects (mean age 39.0 years) were enrolled in this study. The subjects were matched by sex, age, and smoking and alcohol consumption habits. In the case group, the frequencies of GSTT1-null and GSTM1-null genotypes were 24.1 and 51.9%, respectively, whereas for the control group, the frequencies were 12.8 and 46.2%, respectively. Analysis performed with respect to the risk of developing TRS associated with the GSTT1 and GSTM1 deletion polymorphisms, resulted in odds ratio (OR) values of 2.1 and 1.2, respectively. However, the association was not found to be significant (p = 0.1229 and p = 0.5916, respectively). The analysis performed with respect to the combined genotypes of GSTT1 and GSTM1 revealed that the double-null genotype confers a 4.6-fold increased risk of developing TRS (p = 0.0412).ConclusionThe results of the present study indicate that a combination of GST deficiencies may play a role in enhanced susceptibility to TRS, and the present genotype of one of these genes may buffer the deficiency caused by the lack (null genotype) of the other. The results suggest that combined deletion polymorphisms of GSTT1 and GSTM1 can have implications in the prediction of the clinical course of the disease.

Microorganisms play a vital role in bioethanol production whose usage as fuel energy is increasing worldwide. The filamentous fungus Neurospora crassa synthesize and secrete the major enzymes involved in plant cell wall deconstruction. The production of cellulases and hemicellulases is known to be affected by the environmental pH; however, the regulatory mechanisms of this process are still poorly understood. In this study, we investigated the role of the pH regulator PAC-3 in N. crassa during their growth on sugarcane bagasse at different pH conditions. Our data indicate that secretion of cellulolytic enzymes is reduced in the mutant Δpac-3 at alkaline pH, whereas xylanases are positively regulated by PAC-3 in acidic (pH 5.0), neutral (pH 7.0), and alkaline (pH 10.0) medium. Gene expression profiles, evaluated by real-time qPCR, revealed that genes encoding cellulases and hemicellulases are also subject to PAC-3 control. Moreover, deletion of pac-3 affects the expression of transcription factor-encoding genes. Together, the results suggest that the regulation of holocellulase genes by PAC-3 can occur as directly as in indirect manner. Our study helps improve the understanding of holocellulolytic performance in response to PAC-3 and should thereby contribute to the better use of N. crassa in the biotechnology industry.

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In the present study, we examined the characteristics of cDNA, the regulation of the gene expression of Paracoccidioides brasiliensis MLS (Pbmls), and the enzymatic activity of the protein P. brasiliensis MLS (PbMLS) from the P. brasiliensis Pb01 isolate. Pbmls cDNA contains 1617 bp, encoding a protein of 539 amino acids with a predicted molecular mass of 60 kDa. The protein presents the MLSs family signature, the catalytic residues essential for enzymatic activity and the peroxisomal/glyoxysomal targeting signal PTS1. The high level of Pbmls transcript observed in the presence of two-carbon (2C) sources suggests that in P. brasiliensis, the primary regulation of carbon flux into the glyoxylate cycle (GC) was at the level of the Pbmls transcript. The gene expression, protein level, and enzymatic activity of Pbmls were highly induced by oxalurate in the presence of glucose and by proline in the presence of acetate. In the presence of glucose, the gene expression, protein level, and enzymatic activity of Pbmls were mildly stimulated by proline. Our results suggested that PbMLS condenses acetyl-CoA from both 2C sources (GC) and nitrogen sources (from proline and purine metabolism) to produce malate. The regulation of Pbmls by carbon and nitrogen sources was reinforced by the presence of regulatory motifs CREA and UIS found in the promoter region of the gene.