Aline Helena da Silva Cruz

Ambient pH sensing in filamentous fungi: Pitfalls in elucidating regulatory hierarchical signaling networks

In this article, the experiments used to construct the ambient pH‐signaling network involved in the secretion of enzymes by filamentous fungi have been reviewed, focusing on the phosphate‐repressible phosphatases in Aspergillus nidulans. Classic and molecular genetics have been used to demonstrate that proteolysis of the transcription factor PacC at alkaline ambient pH is imperative for its action, implying that the full‐length version is not an active molecular form of PacC. It has been hypothesized that the transcriptional regulator PacC may be functional at both acidic and alkaline ambient pH, in either the full‐length or the proteolyzed form, if it carries a pal‐dependent molecular tag. The products of the pal genes are involved in a metabolic pathway that led to the synthesis of effector molecules that tag the pacC product, perhaps facilitating its proteolysis.

Transcription of Aspergillus nidulans pacC is modulated by alternative RNA splicing of palB

Fungi have evolved elaborate signal transduction networks for remodeling metabolic pathways to scavenge nutrients, including the secretion of nutritional enzymes. This adaptive response involves the conserved PacC/Pal signal transduction pathway, which mediates the transcriptional response to ambient pH. In this study, we show that transcription of the gene for PacC is modulated in response to nutrient changes, phosphate and carbon sources, and pH. In addition, we show that transcription of pacC is modulated in response to alternative RNA splicing of the palB gene. These results reveal novel aspects of the complex network involved in modulation of pacC.

Deletion of pH regulator pac-3 affects cellulase and xylanase activity during sugarcane bagasse degradation by Neurospora crassa.

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.

Transcription of N- and O-linked mannosyltransferase genes is modulated by the pacC gene in the human dermatophyte Trichophyton rubrum

In fungi, ambient pH sensing involves the activation of the Pal/PacC signalling pathway. In the dermatophyte Trichophyton rubrum, pH‐dependent secretion of keratinases, which are major virulence determinants, is affected by disruption of the pacC gene. Here, the transcription profiling of the genes coding for N‐ and O‐linked mannosyltransferases, enzymes involved in protein glycosylation, was evaluated in T. rubrum in response to disruption of the pacC gene and growth in keratin, glucose, and glucose plus glycine. We show that transcription of these mannosyltransferase genes is affected by nutrients at acidic pH and by PacC.

Drosophila: um importante modelo biológico para a pesquisa e o ensino de Genética

Uma das maiores dificuldades enfrentadas pelos professores de biologia e organizar o conteudo a ser ministrado de maneira a garantir a eficiencia do processo de ensino-aprendizagem. Nesse sentido, as Drosophilas tem sido aliadas dos professores durante aulas teoricas e praticas nao so de zoologia, mas tambem de genetica e ecologia, alem de serem modelos utilizados intensamente na pesquisa, o que permite aos professores uma complementacao das aulas com debates de atualidades cientificas utilizando um modelo conhecido pelos alunos. Estes organismos sao modelos de referencia no ensino e pesquisa devido a facil manutencao laboratorial, baixo custo, por sobrevivem a temperatura ambiente, serem facilmente observaveis com lupa e possuirem genoma relativamente menor que de outros eucariontes. Dada a importância destes insetos, o presente trabalho consiste em um breve historico sobre o uso das Drosophilas seja na pesquisa ou na educacao, descrevendo o modo como estes organismos podem ser utilizados no ensino em aulas praticas e teoricas, como bioindicadores na natureza, e na pesquisa em testes de genotoxicidade e doencas humanas, como a doenca de Parkinson, por exemplo. Tornando-se um trabalho formativo e informativo para graduandos de Ciencias Biologicas e profissionais atuantes no ensino basico e superior, de instituicoes publicas e privadas, que possuem ou nao boas condicoes laboratoriais para desenvolverem suas praticas.

Do GST polymorphisms influence in the pathogenesis of diabetic nephropathy

Diabetic patients often develop Diabetic Nephropathy (DN) despite severe long-lasting hyperglycemia, while others develop DN even under intensive insulin therapy. This indicates that factors other than chronic hyperglycemia may also contribute to the susceptibility to the development of DN. The purpose of this case-control study was to investigate the possible role of GSTM1 and GSTT1 deletion polymorphisms, and Single Nucleotide Polymorphism (SNP), GSTP1 313 A > G (Ile105Val), in DN susceptibility. Multiple logistic regression analysis revealed that the occurrence of GST polymorphisms in the Central Brazilian population was not associated with increased risk of DN. However, the presence GSTT1 null genotype suggest an increase trend in systolic blood pressure and opposite inference was observed for the GSTP1 genotype (Ile⁄Val or Val⁄Val). On the order hand, other studies may clarify the relationship of these polymorphisms with DN and help in the prevention of this disease.

Clinical data and risk factors for diabetic nephropathy in Brazilian central population

This article describes data set of the profile of patients diagnosed with Diabetic Nephropathy (DN) undergoing hemodialysis and followed-up by Hemodialysis Service in medical centers in Goiânia, Go, Brazil. These data describe specifically the demographic, clinical, and lifestyle variables of 101 patients. In addition, these data provide detailed clinical associations about the profile of patients diagnosed with DN and which are made publicly available to enable critical or extended analyzes. For further interpretation of the data presented in this article, see the research article: Do GST polymorphisms influence in the pathogenesis of diabetic nephropathy? (Lima et al., 2018).

GSTM1/GSTT1 double-null genotype increases risk of treatment-resistant schizophrenia: A genetic association study in Brazilian patients

Background The 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 findings We 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). Conclusion The 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.

AS PESQUISAS E O TRATAMENTO ENVOLVENDO CÉLULAS-TRONCO: UMA ABORDAGEM INVESTIGATIVA E SUAS IMPLICAÇÕES BIOÉTICAS

As celulas-tronco sao classificadas em embrionarias e adultas, e tem sido aplicadas, por exemplo, na analise do desenvolvimento humano, terapias genicas e na producao de linhagens especificas para transplantes. Por isso, existe uma tendencia internacional em legalizar de forma etica os protocolos e as pesquisas cientificas que utilizam estes tipos celulares. Principalmente porque os resultados destas pesquisas revelam esperancas de melhoria na qualidade de vida dos seres humanos portadores de doencas que ate o momento sao consideradas incuraveis, ou que levam ao termino da vida num processo muito rapido e doloroso em relacao as demais. Mas interligado as perspectivas de cura estao os questionamentos e discussoes eticas, morais e religiosas a respeito do uso destas celulas. Nesse sentido, o objetivo desse trabalho foi de verificar a opiniao e o conhecimento de algumas pessoas da sociedade sobre a utilizacao de celulas-tronco embrionarias em pesquisas e no tratamento de doencas degenerativas. Para tanto os participantes da presente pesquisa responderam um questionario cujos resultados revelaram que a maioria dos entrevistados considera que pesquisas envolvendo celulas-tronco sao inevitaveis, mas tambem que esta tecnologia trara beneficios. Eles tambem sugerem que embrioes congelados nas clinicas de fertilizacao devem ter outro destino alem das pesquisas e tratamento de doencas degenerativas, como por exemplo, a doacao para casais que desejam ter filhos.