RESUMO
Aspergillus fumigatus causes a range of human and animal diseases collectively known as aspergillosis. A. fumigatus possesses and expresses a range of genetic determinants of virulence, which facilitate colonisation and disease progression, including the secretion of mycotoxins. Gliotoxin (GT) is the best studied A. fumigatus mycotoxin with a wide range of known toxic effects that impair human immune cell function. GT is also highly toxic to A. fumigatus and this fungus has evolved self-protection mechanisms that include (i) the GT efflux pump GliA, (ii) the GT neutralising enzyme GliT, and (iii) the negative regulation of GT biosynthesis by the bis-thiomethyltransferase GtmA. The transcription factor (TF) RglT is the main regulator of GliT and this GT protection mechanism also occurs in the non-GT producing fungus A. nidulans. However, the A. nidulans genome does not encode GtmA and GliA. This work aimed at analysing the transcriptional response to exogenous GT in A. fumigatus and A. nidulans, two distantly related Aspergillus species, and to identify additional components required for GT protection. RNA-sequencing shows a highly different transcriptional response to exogenous GT with the RglT-dependent regulon also significantly differing between A. fumigatus and A. nidulans. However, we were able to observe homologs whose expression pattern was similar in both species (43 RglT-independent and 11 RglT-dependent). Based on this approach, we identified a novel RglT-dependent methyltranferase, MtrA, involved in GT protection. Taking into consideration the occurrence of RglT-independent modulated genes, we screened an A. fumigatus deletion library of 484 transcription factors (TFs) for sensitivity to GT and identified 15 TFs important for GT self-protection. Of these, the TF KojR, which is essential for kojic acid biosynthesis in Aspergillus oryzae, was also essential for virulence and GT biosynthesis in A. fumigatus, and for GT protection in A. fumigatus, A. nidulans, and A. oryzae. KojR regulates rglT, gliT, gliJ expression and sulfur metabolism in Aspergillus species. Together, this study identified conserved components required for GT protection in Aspergillus species.
Assuntos
Aspergillus/crescimento & desenvolvimento , Gliotoxina/farmacologia , Metiltransferases/genética , Fatores de Transcrição/genética , Aspergillus/efeitos dos fármacos , Aspergillus/genética , Aspergillus fumigatus/efeitos dos fármacos , Aspergillus fumigatus/genética , Aspergillus fumigatus/crescimento & desenvolvimento , Aspergillus nidulans/efeitos dos fármacos , Aspergillus nidulans/genética , Aspergillus nidulans/crescimento & desenvolvimento , Aspergillus oryzae/efeitos dos fármacos , Aspergillus oryzae/genética , Aspergillus oryzae/crescimento & desenvolvimento , Proteínas Fúngicas/genética , Perfilação da Expressão Gênica , Regulação Fúngica da Expressão Gênica , Gliotoxina/biossíntese , RNA-SeqRESUMO
Bendamustine, an anticancer drug with alkylating properties, is widely used to treat hematological malignancies. Since the nitrogen mustard family alkylators induce DNA damages and have been associated with an elevated risk of second malignancy, current study evaluates the cytotoxic, mutagenic, and recombinogenic effects of bendamustine by using, respectively the mitotic index assay, the in vitro mammalian cell micronucleus test (Mnvit) and the chromosome aberration (CA) test in human peripheral lymphocytes, and the in vivo homozygotization assay in Aspergillus nidulans, which detects the loss of heterozygosity (LOH) due to somatic recombination. Bendamustine (6.0 µg/ml, 9.0 µg/ml, and 12.0 µg/ml) induced a statistically significant concentration-related increase in the frequencies of micronuclei and a significant reduction in the cytokinesis block proliferation index (CBPI) rates when compared to negative control. In the CA test, bendamustine significantly increased the frequencies of structural aberrations at the three tested concentrations when compared to the negative control. Aspergillus nidulans diploids, obtained after bendamustine treatment (6.0 µg/ml, 12.0 µg/ml, and 24.0 µg/ml), produced, after haploidization, homozygotization index (HI) rates higher than 2.0 and significantly different from the negative control. Since bendamustine showed genotoxic effects in all tested concentrations, two of them corresponding to the peak plasma concentrations observed in cancer patients treated with bendamustine, data provided in the current research work may be useful to identify the most appropriate dosage regimen to achieve the efficacy and safety of this anticancer medication.
Assuntos
Antineoplásicos Alquilantes/toxicidade , Aspergillus nidulans/efeitos dos fármacos , Cloridrato de Bendamustina/toxicidade , Aberrações Cromossômicas/induzido quimicamente , Perda de Heterozigosidade/efeitos dos fármacos , Linfócitos/efeitos dos fármacos , Adolescente , Adulto , Aspergillus nidulans/genética , Células Cultivadas , Relação Dose-Resposta a Droga , Humanos , Linfócitos/patologia , Micronúcleos com Defeito Cromossômico/induzido quimicamente , Testes para Micronúcleos , Adulto JovemRESUMO
Medicinal plants such as Aloe arborescens Miller and Aloe barbadensis Miller are used by the general population to treat various diseases. Therefore, the aim of this study was to evaluate the antimutagenicity of these two species using a methG1 system in Aspergillus nidulans and the comet assay in rats. The animals were treated with the plants at concentrations of 360 and 720 mg/kg body weight (1 and 2, respectively) by gavage for 14 days, followed by the administration of etoposide on treatment day 8. Blood samples were prepared for analysis of DNA damage. For the test in A. nidulans, the biA1methG1 lineage conidia were treated for 4 h with both plant species at concentrations of 4 and 8% (w/v). Then, they were washed and plated on a selective medium for frequency analysis of survival and mutation. The results of the comet assay showed that both plants were antigenotoxic compared to etoposide, which was not a typical response of methG1 systems, where only the highest concentration of plant extracts usually exhibit beneficial effects. This study demonstrates the potential antigenotoxicity and antimutagenicity of the Aloe plants tested and, therefore, supports their use as a form of preventive therapy and for health maintenance by the population.
Assuntos
Aloe/química , Aspergillus nidulans/efeitos dos fármacos , DNA/química , Etoposídeo/antagonistas & inibidores , Mutagênicos/toxicidade , Extratos Vegetais/farmacologia , Administração Oral , Animais , Aspergillus nidulans/crescimento & desenvolvimento , Ensaio Cometa , DNA/genética , Dano ao DNA , Etoposídeo/toxicidade , Masculino , Testes de Sensibilidade Microbiana , Testes de Mutagenicidade , Extratos Vegetais/isolamento & purificação , Plantas Medicinais , Ratos , Ratos Wistar , Esporos Fúngicos/efeitos dos fármacos , Esporos Fúngicos/crescimento & desenvolvimentoRESUMO
The photoprotective and antimutagenic activity of opened and closed basidiocarps of Agaricus subrufescens (=A. blazei; =A. brasiliensis) obtained by different extraction methods were evaluated on Aspergillus nidulans conidia submitted to ultraviolet (UV) light. The aqueous extracts were obtained by three extraction methods: maceration, infusion, and decoction, at two different extraction times. The extracts of A. subrufescens did not present toxicity for A. nidulans conidia. A suspension of A. nidulans conidia was submitted to extracts before and after the exposure to UV light. All basidiocarp extracts, regardless of the extraction method or development stage, protected A. nidulans conidia against the damaging effects of the mutagenic agent. The antimutagenic and photoprotective activity was strengthened with extracts obtained by 168-h maceration, followed by 24-h maceration and 60-min infusion and, at last, by 30-min infusion. Although the extracts presented protector effect as well as recoverer effect to the action of UV light, the preventive effect was more evident. Differences in the biological activity in function of the different development stages were detected with greater antimutagenic and photoprotective activity for the opened basidiocarps. However, the extraction method is the most important factor to be considered when compared to the basidiocarp development stage to obtain better antimutagenic and photoprotective activity of A. subrufescens basidiocarps.
Assuntos
Agaricus/química , Antimutagênicos/isolamento & purificação , Aspergillus nidulans/efeitos dos fármacos , Aspergillus nidulans/efeitos da radiação , Viabilidade Microbiana/efeitos dos fármacos , Viabilidade Microbiana/efeitos da radiação , Protetores contra Radiação/isolamento & purificação , Antimutagênicos/metabolismo , Carpóforos/química , Protetores contra Radiação/metabolismo , Esporos Fúngicos/efeitos dos fármacos , Esporos Fúngicos/efeitos da radiaçãoRESUMO
Este artigo propõe estudar os primeiros 12 anos de existência do Instituto de Radium de Minas Gerais, fundado em 1922. Sua atuação na luta contra o câncer no Brasil, ainda pouco conhecida, começa a ser esboçada pelo estudo de documentação institucional inédita. Através de um banco de dados elaborado com informações constantes em seu livro de registro de pacientes, foram feitos levantamentos estatísticos dos tipos de câncer e das formas de tratamento existentes entre 1923 e 1935. Esse livro faz parte de um conjunto de outros cinco recentemente descobertos no Centro de Memória da Medicina/UFMG. A documentação permite resgatar os primórdios das intervenções de radioterapia no país e acompanhar seu desenvolvimento e a influência exercida por esse hospital modelo.
This article proposes to study the first 12 years of the Minas Gerais Radium Institute, founded in 1922. Its work in the fight against cancer in Brazil, albeit still little known, is coming to light as its institutional documents are studied. A database has been prepared using information from its patient register, based on which statistical analyses have been done to identify the types of cancer and treatments available there between 1923 and 1935. This register is one of five recently unearthed at the Medicine Memory Center of the Universidade Federal de Minas Gerais. Through them, the earliest experiments in radiotherapy in Brazil can be reconstituted, and its development and the influence of this model hospital can be mapped out.
Assuntos
Feminino , Humanos , Masculino , Aspergillus nidulans/enzimologia , Dioxigenases , Ácido Homogentísico/análise , Oxigenases/metabolismo , Espectrofotometria/métodos , Alcaptonúria/metabolismo , Aspergillus nidulans/efeitos dos fármacos , Aspergillus nidulans/metabolismo , Cromatografia Líquida de Alta Pressão , Ácido Homogentísico/metabolismo , Ácido Homogentísico/urina , Oxigenases/genética , Fenilacetatos/metabolismo , Fenilacetatos/farmacologia , Sensibilidade e EspecificidadeRESUMO
The increasing tolerance to currently-used fungicides is a major problem both in clinical and agricultural areas leading to an urgent need for the development of novel antifungal strategies. This study investigated the in vitro antimicrobial photo treatment (APT) of conidia of the plant-pathogenic fungus Colletotrichum acutatum and the ascomycete Aspergillus nidulans with the furocoumarins 8-methoxypsoralen (8-MOP) and isopimpinellin, and a mixture of two coumarins (7-methoxy coumarin and citropten). Subcellular localization of the photosensitizer 8-MOP was also determined in C. acutatum conidia. Additionally, the effects of APT on the leaves of the plant host Citrus sinensis were determined. APT with 8-MOP (50µM) led to a reduction of approximately 4 logs in the survival of the conidia of both species, and the mixture of the two coumarins (12.5mgL(-1)) resulted in a reduction of approximately 4 logs for A. nidulans and 3 logs for C. acutatum. Isopimpinellin (50µM) displayed a reduction of 4 logs for A. nidulans but less than 2 logs for C. acutatum. Washing the conidia to remove unbound photosensitizers before light exposure reduced the photodynamic inactivation of C. acutatum both with 8-MOP and the mixture of the two coumarins. The reduction was smaller for A. nidulans. 8-MOP spread throughout the cytoplasm and accumulated in structures such as lipid bodies of C. acutatum conidia. No damage to orange tree leaves was observed after APT with any of the photosensitizers.
Assuntos
Antifúngicos/farmacologia , Aspergillus nidulans/efeitos dos fármacos , Colletotrichum/efeitos dos fármacos , Cumarínicos/farmacologia , Furocumarinas/farmacologia , Metoxaleno/farmacologia , Citrus/química , Citrus/microbiologia , Colletotrichum/patogenicidade , Cumarínicos/química , Cumarínicos/isolamento & purificação , Furocumarinas/isolamento & purificação , Metoxaleno/isolamento & purificação , Estrutura Molecular , Fármacos Fotossensibilizantes/farmacologia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/microbiologia , Esporos Fúngicos/efeitos dos fármacos , Luz SolarRESUMO
Mitotic recombination is a process involved in carcinogenesis which can lead to genetic loss through the loss of heterozygosity. The recombinogenic potentials of two anticancer drugs topoisomerase I inhibitors, camptothecin (CPT) and irinotecan (CPT-11), were evaluated in the present study. The homozygotization assay, which assess the induction of mitotic recombination and gene homozygosis, as well as the heterozygous A757//UT448 diploid strain of Aspergillus nidulans were employed. The three non-cytotoxic concentrations of CPT (3.5 ng mL-1, 10.5 ng mL-1 and 17.4 ng mL-1) were found to induce both mitotic recombination and gene homozygosis. CPT treatment produced three diploids homozygous, for nutritional and conidia color genes, and Homozygotization Indices (HI) significantly different from negative control. On the other hand, only the highest CPT-11 concentration tested (18 µg mL-1), corresponding to the maximal single chemotherapeutic dose, produced HI values higher than 2.0 and significantly different from negative control HI values. The recombinogenic effects of both topoisomerase I blockers were associated with the recombinational repair of DNA strand breaks induced by CPT and CPT-11. The anticancer drugs CPT and CPT-11 may be characterized as secondary malignancies promoters in cancer patients after chemotherapy treatment.
Assuntos
Aspergillus nidulans/efeitos dos fármacos , Camptotecina/análogos & derivados , Camptotecina/toxicidade , Recombinação Genética/efeitos dos fármacos , Inibidores da Topoisomerase I/toxicidade , Aspergillus nidulans/genética , Diploide , Homozigoto , Irinotecano , Mitose/efeitos dos fármacos , Mitose/genética , Testes de MutagenicidadeRESUMO
The increasing tolerance to currently used fungicides in both clinical and agricultural areas is of great concern. The nonconventional light-based approach of antimicrobial photodynamic treatment (APDT) is a promising alternative to conventional fungicides. We evaluated the effects of APDT with four phenothiazinium derivatives (methylene blue [MB], new methylene blue N [NMBN], toluidine blue O [TBO], and the novel pentacyclic phenothiazinium photosensitizer [PS] S137) on conidia of three fungal species (Colletotrichum acutatum, Colletotrichum gloeosporioides, and Aspergillus nidulans). The efficacy of APDT with each PS was determined, initially, based on photosensitizer MICs. Additionally, the effects of APDT with two selected PSs (NMBN and S137) on survival of conidia were evaluated. The subcellular localization of the PS in C. acutatum conidia was determined. The effects of photodynamic treatments on leaves of the plant host Citrus sinensis were also investigated. APDT with S137 showed the lowest MIC. MICs for S137 were 5 µM for the three fungal species when a fluence of 25 J cm(-2) was used. APDT with NMBN (50 µM) and S137 (10 µM) resulted in a reduction in the survival of the conidia of all species of approximately 5 logs with fluences of ≥15 J cm(-2). Washing of the conidia before light exposure did not prevent photodynamic inactivation. Both NMBN and S137 accumulated in cytoplasmic structures, such as lipid bodies, of C. acutatum conidia. No damage to orange tree leaves was observed after APDT.
Assuntos
Antifúngicos/farmacologia , Colletotrichum/efeitos dos fármacos , Colletotrichum/fisiologia , Viabilidade Microbiana/efeitos dos fármacos , Fenotiazinas/farmacologia , Fármacos Fotossensibilizantes/farmacologia , Aspergillus nidulans/efeitos dos fármacos , Aspergillus nidulans/fisiologia , Citrus sinensis/microbiologia , Fungos , Testes de Sensibilidade Microbiana , Esporos Fúngicos/efeitos dos fármacosRESUMO
Metformin is a hypoglycemiant drug prescribed for the treatment and control of the type 2 diabetes mellitus. Recently, the potential efficacy of this antidiabetic drug as an anticancer agent has been demonstrated in various mammalian cancer cells. This report evaluates the mutagenic as well as the recombinogenic potentials of the metformin drug in therapeutically relevant plasma concentrations (12.5 µM, 25.0 µM or 50.0 µM). Since the loss of heterozygosity is a process associated with carcinogenesis, the recombinogenic potential of such a drug was evaluated by the homozygotization assay using a heterozygous diploid strain of Aspergillus nidulans. The homozigotization indices (HI) for the genetic markers from the metformin-treated diploids were not statistically different from the negative control (non-treated diploids). For the first time, this indicated a lack of recombinogenic activity of the antidiabetic drug. The mutagenic potential of the metformin drug was evaluated by the chromosome aberrations and the micronuclei tests in human lymphocytes cultures. The metformin drug did not show any significant increase either in the numerical or in the structural chromosome aberrations and did not affect significantly the mitotic index when compared to the negative control. In the in vitro micronucleus test, the drug did not increase the number of micronuclei or nuclear buds when compared with the negative control. The data in this study suggest that the metformin drug is not a secondary cancer inducer, since it has neither showed recombinogenic nor mutagenic activities when used in pharmacological concentrations.
Assuntos
Metformina/toxicidade , Mutagênicos/toxicidade , Adulto , Aspergillus nidulans/citologia , Aspergillus nidulans/efeitos dos fármacos , Cromátides/metabolismo , Aberrações Cromossômicas/efeitos dos fármacos , Segregação de Cromossomos/efeitos dos fármacos , Cromossomos de Mamíferos/metabolismo , Diploide , Feminino , Haploidia , Heterozigoto , Homozigoto , Humanos , Linfócitos/efeitos dos fármacos , Linfócitos/metabolismo , Masculino , Testes para Micronúcleos , Índice Mitótico , Adulto JovemRESUMO
Imidocarb dipropionate (IMD) is a chemotherapeutic agent prescribed for the treatment and control of babesiosis; it is known to be a nucleic acid synthesis inhibitor. Although it is an effective babesicide, there are reports of persistent IMD residues retained at high levels in edible tissues of cattle, swine and sheep, raising concerns about potential effects on humans. Since the carcinogenic potential of a chemical compound can be assessed through its effect on the homologous recombination, we investigated whether IMD is recombinogenic in Aspergillus nidulans diploid cells and whether it is capable of inducing homozygosis in genes that were previously heterozygous. This analysis was done with a homozygotization assay applied to a heterozygous diploid strain of A. nidulans. IMD used at non-toxic concentrations (2.5 to 10.0 µM) was recombinogenic, demonstrated by homozygotization indices higher than 2.0 for diploid markers. A diploid homozygous for genetic markers from chromosomes I and II was also produced. Since DNA replication blockers that induce DNA strand breaks have been classified as potent inducers of homologous recombination, the recombinogenic potential of IMD may be due to induction of recombinational repair.
Assuntos
Antiprotozoários/farmacologia , Aspergillus nidulans/citologia , Aspergillus nidulans/genética , Diploide , Imidocarbo/análogos & derivados , Mitose/efeitos dos fármacos , Recombinação Genética/efeitos dos fármacos , Animais , Aspergillus nidulans/efeitos dos fármacos , Babesia/efeitos dos fármacos , Bovinos , Cromossomos Fúngicos/genética , Troca Genética/efeitos dos fármacos , Genótipo , Imidocarbo/farmacologiaRESUMO
Cutinases are versatile carboxylic ester hydrolases with great potential in many biocatalytic processes, including biodiesel production. Genome sequence analysis of the model organism Aspergillus nidulans reveals four genes encoding putative cutinases. In this work, we purified and identified for the first time a cutinase (ANCUT2) produced by A. nidulans. ANCUT2 is a 29-kDa protein which consists of 255 amino acid residues. Comparison of the amino acid sequence of ANCUT2 with other microbial cutinase sequences revealed a high degree of homology with other fungal cutinases as well as new features, which include a serine-rich region and conserved cysteines. Cutinase production with different lipidic and carbon sources was also explored. Enzyme activity was induced by olive oil and some triacylglycerides and fatty acids, whereas it was repressed by glucose (1%) and other sugars. In some conditions, a 22-kDa post-translational processing product was also detected. The cutinase nature of the enzyme was confirmed after degradation of apple cutin.
Assuntos
Aspergillus nidulans/citologia , Hidrolases de Éster Carboxílico/biossíntese , Espaço Extracelular/metabolismo , Óleos de Plantas/farmacologia , Sequência de Aminoácidos , Aspergillus nidulans/efeitos dos fármacos , Aspergillus nidulans/genética , Aspergillus nidulans/crescimento & desenvolvimento , Carbono/farmacologia , Hidrolases de Éster Carboxílico/química , Hidrolases de Éster Carboxílico/isolamento & purificação , Hidrolases de Éster Carboxílico/metabolismo , Meios de Cultura , Evolução Molecular , Espaço Extracelular/efeitos dos fármacos , Espaço Extracelular/enzimologia , Ácidos Graxos/farmacologia , Dados de Sequência Molecular , Peso Molecular , Nitrogênio/farmacologia , Azeite de Oliva , Filogenia , Processamento de Proteína Pós-Traducional/efeitos dos fármacos , Triglicerídeos/farmacologiaRESUMO
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.
Assuntos
Processamento Alternativo/genética , Aspergillus nidulans/genética , Cisteína Endopeptidases/genética , Proteínas Fúngicas/genética , Fatores de Transcrição/genética , Transcrição Gênica/genética , Processamento Alternativo/efeitos dos fármacos , Aspergillus nidulans/efeitos dos fármacos , Carbono/farmacologia , Cisteína Endopeptidases/deficiência , Regulação Fúngica da Expressão Gênica/efeitos dos fármacos , Regulação Fúngica da Expressão Gênica/genética , Concentração de Íons de Hidrogênio , Mutação , Fosfatos/farmacologia , Reação em Cadeia da Polimerase em Tempo Real , Transcrição Gênica/efeitos dos fármacosRESUMO
FOH (farnesol), a non-sterol isoprenoid produced by dephosphorylation of farnesyl pyrophosphate, has been shown to inhibit proliferation and induce apoptosis. We have been using Aspergillus nidulans and FOH as a model system and cell death stimulus, respectively, aiming to understand by which means filamentous fungi are driven towards cell death. Here, we review some of our findings about FOH-induced cell death in A. nidulans.
Assuntos
Aspergillus nidulans/efeitos dos fármacos , Aspergillus nidulans/fisiologia , Morte Celular/efeitos dos fármacos , Farneseno Álcool/farmacologia , Animais , Aspergillus nidulans/citologia , Morte Celular/fisiologia , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Humanos , Mitocôndrias/metabolismo , Resposta a Proteínas não Dobradas/fisiologiaRESUMO
Previously, we demonstrated that the Aspergillus nidulans calC2 mutation in protein kinase C pkcA was able to confer tolerance to farnesol (FOH), an isoprenoid that has been shown to inhibit proliferation and induce apoptosis. Here, we investigate in more detail the role played by A. nidulans pkcA in FOH tolerance. We demonstrate that pkcA overexpression during FOH exposure causes increased cell death. FOH is also able to activate several markers of endoplasmic reticulum (ER) stress and the unfolded protein response (UPR). Our results suggest an intense cross-talk between PkcA and the UPR during FOH-induced cell death. Furthermore, the overexpression of pkcA increases both mRNA accumulation and metacaspases activity, and there is a genetic interaction between PkcA and the caspase-like protein CasA. Mutant analyses imply that MAP kinases are involved in the signal transduction in response to the effects caused by FOH.
Assuntos
Aspergillus nidulans/efeitos dos fármacos , Aspergillus nidulans/enzimologia , Farneseno Álcool/farmacologia , Proteínas Fúngicas/metabolismo , Proteína Quinase C/metabolismo , Resposta a Proteínas não Dobradas/efeitos dos fármacos , Aspergillus nidulans/genética , Aspergillus nidulans/metabolismo , Retículo Endoplasmático/efeitos dos fármacos , Retículo Endoplasmático/genética , Retículo Endoplasmático/metabolismo , Proteínas Fúngicas/genética , Regulação Fúngica da Expressão Gênica/efeitos dos fármacos , Proteína Quinase C/genéticaRESUMO
This report evaluates the potential of the antidepressant drug citalopram to induce homozygotization of genes previously present in a heterozygous condition, by homologous recombination. In order to address this question, a heterozygous diploid strain of the filamentous fungus Aspergillus nidulans and the homozygotization assay were utilized. Non-cytotoxic concentrations of citalopram (50, 75 and 100 µmol/L) showed a strong recombinogenic effect in A. nidulans, inducing homozygosis of the diploid strain's nutritional markers. The genetic markers exhibited homozygotization index (HI) rates higher than 2.0 and significantly different from HI control ones. Since citalopram has been previously characterized as a DNA synthesis inhibitor, the recombinogenic potential of this antidepressant in A. nidulans may be associated with the recombinational repair of citalopram-induced DNA strand breaks.
Assuntos
Antidepressivos de Segunda Geração/toxicidade , Aspergillus nidulans/efeitos dos fármacos , Aspergillus nidulans/genética , Citalopram/toxicidade , Mutagênicos/toxicidade , Recombinação Genética/efeitos dos fármacos , Aspergillus nidulans/citologia , Carcinógenos/toxicidade , Troca Genética/efeitos dos fármacos , Dano ao DNA , Reparo do DNA , Transtorno Depressivo/complicações , Transtorno Depressivo/tratamento farmacológico , Diploide , Genes Fúngicos , Marcadores Genéticos , Heterozigoto , Homozigoto , Humanos , Mitose/efeitos dos fármacos , Mitose/genética , Neoplasias/complicações , Neoplasias/etiologiaRESUMO
Farnesol (FOH) is a nonsterol isoprenoid produced by dephosphorylation of farnesyl pyrophosphate, a catabolite of the cholesterol biosynthetic pathway. These isoprenoids inhibit proliferation and induce apoptosis. Here, we show that Aspergillus nidulans AifA encoding the apoptosis-inducing factor (AIF)-like mitochondrial oxidoreductase plays a role in the function of the mitochondrial Complex I. Additionally, we demonstrated that ndeA-B and ndiA encode external and internal alternative NADH dehydrogenases, respectively, that have a function in FOH resistance. When exposed to FOH, the ΔaifA and ΔndeA strains have increased ROS production while ΔndeB, ΔndeA ΔndeB, and ΔndiA mutant strains showed the same ROS accumulation than in the absence of FOH. We observed several compensatory mechanisms affecting the differential survival of these mutants to FOH.
Assuntos
Fator de Indução de Apoptose/metabolismo , Aspergillus nidulans/enzimologia , Complexo I de Transporte de Elétrons/metabolismo , Farneseno Álcool/metabolismo , Proteínas Fúngicas/metabolismo , Mitocôndrias/enzimologia , Fator de Indução de Apoptose/genética , Aspergillus nidulans/efeitos dos fármacos , Aspergillus nidulans/genética , Aspergillus nidulans/metabolismo , Complexo I de Transporte de Elétrons/genética , Proteínas Fúngicas/genética , Mitocôndrias/genética , Espécies Reativas de Oxigênio/metabolismoRESUMO
Some herbicides are suspected of promoting teratogenic, carcinogenic and mutagenic events. Detection of induced mitotic crossing-over has proven to be an indirect way of testing the carcinogenic properties of suspicious substances, because mitotic crossing-over is involved in the multistep process of carcinogenesis. We examined mitotic crossing-over induced by two commercial herbicides (diuron and trifluralin) in diploid strains of Aspergillus nidulans based on the homozygotization index. Low doses (2.5 microg/mL) of diuron were sufficient to increase the mean homozygotization index in 2.1 and 11.3 times for UT448//UT196 and Dp II-I//UT196, respectively, whereas the same dose of trifluralin increased this mean only 1.2 (UT448//UT196) and 3.5 (Dp II-I//UT196) times, respectively. The lower homozygotization index value found for trifluralin could be due to its interference with mitotic crossing-over in eukaryotic cells. We concluded that the diploid Dp II-I//UT196 of A. nidulans is more sensitive to organic compounds than UT448//UT196; these compounds cause recombinational events at a greater frequency in the latter diploid. This system holds promise as an initial test for carcinogenicity of organic compounds, including herbicides.
Assuntos
Aspergillus nidulans/efeitos dos fármacos , Aspergillus nidulans/genética , Troca Genética/efeitos dos fármacos , Diploide , Herbicidas/toxicidade , Mitose/efeitos dos fármacos , Diurona/toxicidade , Ligação Genética , Genótipo , Homozigoto , Trifluralina/toxicidadeRESUMO
Mercury (Hg) pollution is one of the most serious environmental problems. Due to public concern prompted by the symptoms displayed by people who consumed contaminated fish in Minamata, Japan in 1956, Hg pollution has since been kept under constant surveillance. However, despite considerable accumulation of knowledge on the noxious effects of ingested or inhaled Hg, especially for humans, there is virtually nothing known about the genotoxic effects of Hg. Because increased mitotic crossing over is assumed to be the first step leading to carcinogenesis, we used a sensitive short-term test (homozygotization index) to look for DNA alterations induced by Hg fumes. In one Aspergillus nidulans diploid strain (UT448//UT184), the effects of the Hg fumes appeared scattered all over the DNA, causing 3.05 times more recombination frequencies than the mean for other strains. Another diploid (Dp II-I//UT184) was little affected by Hg. This led us to hypothesize that a genetic factor present in the UT184 master strain genome, close to the nicB8 genetic marker, is responsible for this behavior. These findings corroborate our previous findings that the homozygotization index can be used as a bioassay for rapid and efficient assessment of ecotoxicological hazards.
Assuntos
Poluentes Atmosféricos/toxicidade , Aspergillus nidulans/efeitos dos fármacos , Aspergillus nidulans/genética , Células Eucarióticas/efeitos dos fármacos , Células Eucarióticas/metabolismo , Mercúrio/toxicidade , Testes de Mutagenicidade/métodos , Cromossomos Fúngicos/genética , Troca Genética/efeitos dos fármacos , DNA Fúngico/genética , Diploide , Monitoramento AmbientalRESUMO
Proteins are subject to modification by reactive oxygen species (ROS), and oxidation of specific amino acid residues can impair their biological function, leading to an alteration in cellular homeostasis. Sulfur-containing amino acids as methionine are the most vulnerable to oxidation by ROS, resulting in the formation of methionine sulfoxide [Met(O)] residues. This modification can be repaired by methionine sulfoxide reductases (Msr). Two distinct classes of these enzymes, MsrA and MsrB, which selectively reduce the two methionine sulfoxide epimers, methionine-S-sulfoxide and methionine-R-sulfoxide, respectively, are found in virtually all organisms. Here, we describe the homologs of methionine sulfoxide reductases, msrA and msrB, in the filamentous fungus Aspergillus nidulans. Both single and double inactivation mutants were viable, but more sensitive to oxidative stress agents as hydrogen peroxide, paraquat, and ultraviolet light. These strains also accumulated more carbonylated proteins when exposed to hydrogen peroxide indicating that MsrA and MsrB are active players in the protection of the cellular proteins from oxidative stress damage.
Assuntos
Aspergillus nidulans/enzimologia , Proteínas Fúngicas/metabolismo , Oxirredutases/metabolismo , Aspergillus nidulans/efeitos dos fármacos , Aspergillus nidulans/efeitos da radiação , Proteínas Fúngicas/genética , Deleção de Genes , Humanos , Peróxido de Hidrogênio/toxicidade , Metionina Sulfóxido Redutases , Viabilidade Microbiana , Oxidantes/toxicidade , Estresse Oxidativo , Oxirredutases/genética , Paraquat/toxicidade , Carbonilação Proteica , Raios UltravioletaRESUMO
Farnesol (FOH) is a non-sterol isoprenoid produced by dephosphorylation of farnesyl pyrophosphate, a catabolite of the cholesterol biosynthetic pathway. These isoprenoids inhibit proliferation and induce apoptosis. It has been shown previously that FOH triggers morphological features characteristic of apoptosis in the filamentous fungus Aspergillus nidulans. Here, we investigate which pathways are influenced through FOH by examining the transcriptional profile of A. nidulans exposed to this isoprenoid. We observed decreased mRNA abundance of several genes involved in RNA processing and modification, transcription, translation, ribosomal structure and biogenesis, amino acid transport and metabolism, and ergosterol biosynthesis. We also observed increased mRNA expression of genes encoding a number of mitochondrial proteins and characterized in detail one of them, the aifA, encoding the Apoptosis-Inducing Factor (AIF)-like mitochondrial oxidoreductase. The DeltaaifA mutant is more sensitive to FOH (about 8.0% and 0% survival when exposed to 10 and 100 microM FOH respectively) than the wild type (about 97% and 3% survival when exposed to 10 and 100 microM FOH respectively). These results suggest that AifA is possibly important for decreasing the effects of FOH and reactive oxygen species. Furthermore, we showed an involvement of autophagy and protein kinase C in A. nidulans FOH-induced apoptosis.