The complete genome sequence of Chromobacterium violaceum reveals remarkable and exploitable bacterial adaptability

Chromobacterium violaceum is one of millions of species of free-living microorganisms that populate the soil and water in the extant areas of tropical biodiversity around the world. Its complete genome sequence reveals (i) extensive alternative pathways for energy generation, (ii) ≈500 ORFs for transport-related proteins, (iii) complex and extensive systems for stress adaptation and motility, and (iv) wide-spread utilization of quorum sensing for control of inducible systems, all of which underpin the versatility and adaptability of the organism. The genome also contains extensive but incomplete arrays of ORFs coding for proteins associated with mammalian pathogenicity, possibly involved in the occasional but often fatal cases of human C. violaceum infection. There is, in addition, a series of previously unknown but important enzymes and secondary metabolites including paraquat-inducible proteins, drug and heavy-metal-resistance proteins, multiple chitinases, and proteins for the detoxification of xenobiotics that may have biotechnological applications

Análise do nível de sensibilidade do RT-PCR para a translocação BCR/ABL na leucemia mielóide crônica

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Analysis of mRNA transcripts in chronic myeloid leukemia patients

The nature of BCR/ABL hybrid mRNA was analyzed by RT-PCR in cells from 33 patients (22 males, 11 females) with chronic myeloid leukemia (CML). b3a2 mRNA was found in 14 cases, whereas 13 patients had b2a2 mRNA and six had both kinds of mRNA, with a predominance of the b3a2 type. The type of mRNA present showed no significant correlation with age, hemoglobin level, number of leukocytes and platelets, percentage of blasts or basophils or the presence of splenomegaly at diagnosis. There was also no correlation with sex or duration of the chronic phase. When these results were combined with those reported by other groups, a significant association (P = 0.029) was observed for mRNA type vs. sex, with a predominance of men in the groups expressing b2a2 (2.68:1) and b3a2 (1.33:1). We conclude that the classification of patients according to mRNA type does not homogenize the clinical and hematological data within groups, where variance is large, nor does it allow a differentiation between groups

Comparação de três protocolos de extração de DNA a partir de tecido fixado em formol e incluído em parafina Comparison of three DNA extraction protocols from formaldehyde-fixed and paraffin-embedded tissues

OBJETIVO: Padronizar um método alternativo para extração de DNA a partir de tecido fixado em formol e conservado em arquivos de blocos de parafina, visando à realização de estudos retrospectivos. MÉTODOS: Comparou-se a eficiência de protocolos de extração de DNA a partir de tecido parafinado, para análise por reação em cadeia de polimerase (PCR), tomando-se como parâmetro um protocolo baseado em um kit comercial. Foram feitas extrações do DNA de 60 espécimes por três métodos: o protocolo A, baseado no kit GlassMAX; o B, utilizando-se o kit GFX TM; e o C, tendo como base o método de Banerjee et al.(2). A integridade e a suficiência do DNA presente na amostra foram avaliadas pela amplificação por PCR de um segmento de 110pb do gene da beta-globina humana, com visualização por meio de eletroforese em gel de poliacrilamida, corado pela prata. Resultados: Das 60 amostras analisadas, 45 apresentaram resultado positivo na PCR quando o DNA foi extraído por qualquer um dos três protocolos. Em seis amostras, a amplificação foi positiva apenas para o DNA extraído pelos protocolos A e C. Em três amostras, o resultado foi positivo apenas para o DNA extraído pelo protocolo A, e em duas, apenas para o DNA extraído pelo protocolo C. CONCLUSÕES: O protocolo C apresentou desempenho semelhante ao do protocolo A, com as vantagens de apresentar menor custo, dispensar o uso de kit comercial, além de não utilizar solventes orgânicos, revelando-se uma alternativa viável para a obtenção de DNA a partir de tecido fixado em formol e incluído em parafina.<br>OBJECTIVE: To set up a method for DNA extraction from paraffin embedded cervical cancer specimens, previously formalin-fixed, aiming to accomplish retrospective analysis. METHODS: Sixty specimens were submitted to DNA extraction by three different methods. All of them involved digestion of the tissues by proteinase K, followed by DNA purification, based in three different approaches: protocol A used a DNA isolation kit, GlassMax (Gibco/BRL); protocol B was performed with the kit GFX TM Amersham Pharmacia Biotech; and protocol C was based on the method proposed by Banerjee et al.(2), with modifications. To evaluate the integrity and sufficiency of the DNA, the samples were submitted to a in vitro amplification of a segment of the human beta-globin gene, and the PCR products were analyzed by electrophoresis on 7% polyacrylamide gels, followed by silver staining. Results: Among 60 analyzed samples, 45 showed positive results when submitted to the three protocols. In six samples, PCR fragments were obtained with DNAs extracted through protocols A e C; in three samples, DNA extraction was achieved with protocol A only; and in two samples the DNA was successfully extracted only through protocol C. CONCLUSIONS: Protocols A and C generated similar results. Although protocol C is more labor-intensive and time consuming, it does not require a commercial kit and therefore has a lower cost. Furthermore, it does not require the use of organic solvents and may be considered a good alternative for DNA extraction from paraffin embedded tissues