Rodrigo da Silva Santos

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.

In vitro and ex vivo infection models help assess the molecular aspects of the interaction of Trichophyton rubrum with the host milieu

Dermatophytes are fungal pathogens that cause cutaneous infections such as onychomycosis and athletes foot in both healthy and immunocompromised patients.Trichophyton rubrum is the most prevalent dermatophyte causing human nail and skin infections worldwide, and because of its anthropophilic nature, animal infection models are limited. The purpose of this work was to compare the expression profile of T. rubrum genes encoding putative virulence factors during growth in ex vivo and in vitro infection models. The efficiency of the ex vivo skin infection model was confirmed by scanning electron microscopy (SEM), which showed that the conidia had produced hyphae that penetrated into the epidermis. Quantitative RT-PCR (qRT-PCR) analysis showed that the expression of some genes is modulated in response to the infection model used, as compared to that observed in cells grown in glucose-containing media. We concluded that ex vivo infection models help assess the molecular aspects of the interaction of T. rubrum with the host milieu, and thus provide insights into the modulation of genes during infection.

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.

O processo de formação de professores de Biologia e a interferência das tecnologias e mídias no ensino de Genética e Biologia Molecular

A falta de esclarecimento ou superexposicao das midias acerca da Genetica e Biologia Molecular podem prejudicar seu entendimento ou aceitacao na sociedade. O texto discute a influencia da midia, dos professores ou de pre-conceitos equivocados na assimilacao e/ou aceitacao de temas relacionados a Genetica e Biologia Molecular. Os alunos da modalidade Educacao de Jovens e Adultos (EJA) carregam pre-conceitos ou conceitos erroneos, o que pode ser influenciado por sua bagagem cultural, pela religiao que seguem ou por mau preparo dos educadores em abordar estes temas. Torna-se necessario rever as praticas educativas e a formacao academica dos educadores a fim de evitar a transmissao de informacoes erradas ou a permanencia de pre-conceitos.

A importância da tecnologia de amplificação de ácidos nucléicos para a detecção do vírus da hepatite C em bancos de sangue doi: http://dx.doi.org/10.5892/ruvrv.2012.101.313328

The HCV, agent of hepatitis C, a virus belonging to the genus Hepacivirus of the Flaviviridae family, having a genome comprising a single strand of RNA. HCV transmission occurs via parenteral, such as blood transfusion and blood products, hemophiliacs, intravenous drug users or inhaled, material cutting or piercing can be a vehicle transmitter. The possibility of sexual transmission is still an open question and the transmission is also low, being, however, it may be increased if the patient has strong viremia and/or co-infection with HIV. The diagnosis of hepatitis C is based on serological tests such as ELISA and RIBA and molecular biology techniques. The ELISA detects antibodies against the virus anti-HCV, if the result is indeterminate confirmatory tests must be used such as RIBA. To confirm the diagnosis, we use a qualitative PCR RNA-HCV, and quantitative tests are used to evaluate viral-load, and they are also used to monitor therapeutic response. The nucleic acid amplification technique (NAT) results in a change of conventional laboratory methods, therefore, is quick to identify the “immune gap” period, approximately 50 to 60 days after contamination resulting from 10 to 11 days. The need for incorporation of NAT in blood banks is due to its ability to reduce the immune window period between infection and disease was discovered, thereby increasing transfusion safety.