Avaliação do efeito da inibição do reparo de sítios abásicos na resposta inflamatória celular

Base excision repair (BER) proteins has been associated with functions beyond DNA repair. Apurynic/apyrimidinic endonuclease 1 (APE1) is a multifunctional protein involved in a plethora of cellular activities, such as redox activation of transcription factors, RNA processing and DNA repair. Some studies have described the action of the protein 8-oxoguanine (OGG1) in correcting oxidized lesions in promoters as a step in the transcription of pro-inflammatory cytokines. Despite being especially important in redox activation of transcription factors such as nuclear factor κB (NF-κB) and AP- 1, the repair activity of APE1 has not yet been associated with the inflammatory response. In this study, experimental and bioinformatic analysis approaches have been used to investigate the relationship between inhibition of the repair of abasic sites in DNA by MX, a synthetic molecule designed to inhibt the repair activity of APE1, and the modulation of the inflammatory response. The results showed that treatment of monocytes with lipopolysaccharide (LPS) and MX reduced the expression of cytokines, chemokines and toll-like receptors, and negatively regulated biological immune processes, as macrophages activation, and NF-κB and tumor necrosis factor (TNF-α) and interferon pathways, without inducing cell death. The transcriptomic analysis suggests that LPS/MX treatment induces mitochondrial dysfunction, endoplasmic reticulum stress and activation of autophagy pathways, probably activated by impairment of cellular energy and/or the accumulation of nuclear and mitochondria DNA damage. Additionally, it is proposed that the repair activity of APE1 is required for transcription of inflammatory genes by interaction with abasic sites at specific promoters and recruitment of transcriptional complexes during inflammatory signaling. This work presents a new perspective on the interactions between the BER activity and the modulation of inflammatory response, and suggests a new activity for APE1 protein as modulator of the immune response in a redox-independent manner.

Abordagem da ergonomia para avaliação do treinamento simulado das equipes de resposta à emergência em lançamentos de veículos aeroespaciais

This dissertation introduces a study that aims to analyze the simulated training of emergency teams and proposes recommendations for the current training system in order to improve the collective skills and resilience of these teams when facing possible critical situations, triggered by possible accident occurrences during aerospace vehicle launching operations in the Barreira do Inferno Launch Center in Parnamirim / RN. This is a field, exploratory, descriptive, explanatory, and a case study with a qualitative approach. Therefore, we adopted the ergonomics approach, using the situated method of ergonomic work analysis (AET), combining observational and interactive methods. The relevance of this research is characterized by the contributions to minimize the human and material hazzards resulting from possible accidents in these operations, the scientific contribution of the AET for simulated emergency training analysis in the launching operations of aerospace vehicles - which are complex and involve risk of accidents - and consequently, the scientific contribution to the current process of recovering the Brazilian Space Program. The survey results point to problems of various kinds in the current simulated training system which compromise the safety of the operations. These problems are grouped into four categories: technological, organizational, team training and from the activity itself, regarding more specifically communication and cooperation (among the team members and these ones with other sectors involved in the launching operation) and regarding the coordination of actions. We propose: a) a new training model, from the creation and application of scenarios based on postulated abnormalities, which could simulate real critical situations, in order to train and improve the skills of the emergency response teams especially in terms of communication, coordination and cooperation; b) restructuring and reorganizing the current training system, based on the formal establishment of a managing staff, on the clear division of responsibilities, on the standardization of processes, on the production of management indicators, on the continuous monitoring, on the feedback from trainees about the quality of the training and on the continuing and frequent training of emergency teams.

Estudo da resposta Th17 no transplante renal alogênico: contribuição do eixo quimiotático CCR6/CCL20 e dos polimorfismos gênicos em IL17A e IL17RA

Kidney transplantation is the best treatment for patients who have lost kidney function. Renal transplant patients require accurate immunosuppressive drugs to prevent rejection. In this process T helper cells of the immune system perform key role in the immune response to the graft, and recently the Th17 cells has been investigated by production of IL-17 potent proinflammatory cytokine whose role in the rejection has also been described. Increased of Th17 cell expression has an important association with the development of rejection in renal microenvironment, however the likely mechanism is not well understood. This study aimed to evaluate the Th17 response from the influence of the chemotactic axis CCR6/CCL20 and genetic variants in IL-17 and IL-17RA. We conducted a case-control study involving 148 patients transplanted at the University Hospital Onofre Lopes/UFRN in which assessed by immunohistochemistry protein expression of IL-17 and chemokines CCR6/CCL20 and by PCR-RFLP genetic variants in IL17A and IL17RA. Our results showed no influence of genetic polymorphisms on the outcome of the graft or the protein expression of IL-17. In renal graft microenvironment found several sources producing IL-17: tubular epithelial cells, glomerular cells, neutrophils and cell interstitial infiltration, in turn the expression of chemotactic axis CCR6/CCL20 was restricted to the tubular epithelium cells. There was a slight positive linear correlation between the presence of IL-17 and expression of chemotactic axis CCR6/CCL20 in the microenvironment of renal graft. Therefore, we believe that, combined with our results, further studies with increased "n" sample and greater control over the variables involved in obtaining the renal specimen, can determine more clearly the influence of chemotactic axis CCR6 / CCL20 and polymorphisms in cytokines related to Th17 profile on the control of this cell subtype response in rejection processes to renal allograft.

Efeito da Olmesartana na resposta inflamatória em modelo de mucosite intestinal em ratos

Intestinal Mucositis is inflammation and/or ulceration of mucosa of the gastrointestinal tract caused by anticancer therapies. Histologically, villous atrophy, damage to enterocytes and infiltration of inflammatory cells. Methotrexate (MTX) is a compound that depletes dihydrofolate pools and is widely used in the treatment of leukemia and other malignancies. The aim of this study was to evaluate the effect of Olmesartan (OLM), an angiotensin II receptor antagonist, on an Intestinal Mucositis Model (IMM) induced by MTX in Wistar rats. IMM was induced via intraperitoneal (i.p.) administration of MTX (7 mg/kg) for three consecutive days. The animals were pretreated with oral OLM at 0.5, 1 or 5 mg/kg or with vehicle 30 min prior to exposure to MTX, for three days. Small intestinal (duodenum, jejunum and ileum) homogenates were assayed for levels of the IL-1β, IL-10 and TNF-α cytokines, malondialdehyde and myeloperoxidase activity. Additionally, immunohistochemical analyses of MMP-2, MMP-9, COX-2, RANK/RANKL and SOCS-1 and confocal microscopy analysis of SOCS-1 expression were performed. Treatment with MTX+OLM (5 mg/kg) resulted in a reduction of mucosal inflammatory infiltration, ulcerations, vasodilatation and hemorrhagic areas (p<0.05) as well as reduced concentrations of MPO (p<0.001) and the pro-inflammatory cytokines IL-1β and TNF-α (p<0.01), and increase antiinflammatory cytosine IL-10 (p,0.05). Additionally, the combined treatment reduced expression of MMP-2, MMP-9, COX-2, RANK and RANKL (p<0.05) and increased cytoplasmic expression of SOCS-1 (p<0.05). Our findings confirm the involvement of OLM in reducing the inflammatory response through increased immunosuppressive signaling in an IMM. We also suggest that the beneficial effect of Olmesartan treatment is specifically exerted during the damage through blocking inflammatory cytosines.

Resposta de ovinos naturalmente infectados por nematoides gastrintestinais em pastos de capim-massai

The aim of this study was to evaluate the crossbred sheep Santa Ines response to natural infections by gastrointestinal nematodes in Panicum maximum cv. pastures Massai at different times of grazing. For this it was used 36 crossbred sheep Santa Inês, divided into four groups and randomly distributed in massai-grass pickets naturally infected by gastrointestinal nematodes. In the period from October 2013 to May 2014, the animals were weekly monitored for hematology tests (packed cell volume) and parasitological (egg counts per gram of feces and fecal culture) in order to monitor the level of infection of sheep and they were assessed for weight, body condition score and staining ocular mucosa by FAMACHA© method. Furthermore infective larvae was recovery from pasture in times of pre-and post-grazing pasture. At 35 kg body weight, the animals were slaughtered and necropsied to collect the contents of the abomasum and small and large intestines to recover the adult parasites, carrying out the count and identification. The animals on pasture with a height of 40 cm pre-grazing obtained low nematode eggs in feces (1608 eggs / g) and 33 cm those in pre-grazing the highest average (2,539 eggs / g). The animals in different groups showed mean values of packed cell volume less than 23% (P> 0.05). Regarding to FAMACHA, the animals belonging to the groups 40 and 50 cm pre-grazing remained over 50% of individuals between FAMACHA 1 and 2 , and those to 33 and 45 cm pre-grazing showed mostly between FAMACHA 3, 4 and 5 (69.06% and 58.93%, respectively). In the culture of larvae in feces and recovery of pasture larvae before and after grazing the following genera were found, in order of prevalence: Haemonchus, Trichostrongylus, Oesophagostomum and Strongyloides. The pasture with 33 cm of pre-grazing provided the highest number of larvae recovered both in the pre and post-grazing (1,081 and 715 L3 / 100 g of green matter, respectively). Among the different groups, the sheep had an average weight of between 23 and 26 kg and variation between the body 1 and 3 scores with scores greater frequency of 1.5 to 2.It can be observed that the animals kept at different times of grazing got different answers on the parasite load. Animals kept in 40 cm pre-grazing expressed a satisfactory answer than the other groups (33, 45 and 50 cm), best supporting the action of endoparasites. Moreover, this same height, was recovered fewer infective larvae on pasture in pre and post-grazing.

Resposta clínica periodontal e controle glicêmico em pacientes com e sem diabetes tipo II portadores de periodontite crônica ao tratamento periodontal “full mouth desinfection”

There is a bidirectional association between periodontal disease (PD) and diabetes mellitus, in which diabetes favors the development of PD and PD, if left untreated, can worsen the metabolic control of diabetes. Thus, periodontal disease should be treated to restore periodontal health and reduce the complications of diabetes. Therefore, the objective is assess the effect of full mouth periodontal therapy decontamination (Full Mouth Desinfection - FMD) in diabetic type II patients with chronic periodontitis during 12 months. Thirty-one patients in group one (G1) and 12 in group two (G2) were followed at baseline, 03, 06 09 and 12 months. There following clinical parameters were accessed: probing on bleeding (BOP), visible plaque index (PI), probing depth (PD), clinical attachment level (CAL) and gingival recession (GR). For diabetic patients, there were also made laboratory tests to evaluate blood parameters: fasting glucose and glycated hemoglobin. The results had been analyzed in two ways: all sites in the mouth and another with diseased sites. The Mann-Whitney, Friedman and Wilcoxon tests were used with 5% significance. Intergroup analysis of all sites it is clear that there was no significant difference over time concerning PD, BOP, PI, CAL and RG. However, when evaluating the diseased sites, we observed significant difference for CAL and PD, with higher values in G1. The intragroup analysis for all sites showed a statistically significant reduction at PD, PI and BOP in both groups. Intragroup analysis of periodontal affected sites showed a statistically significant reduction in PD, BOP and CAL in both groups. There was also a statistically significant increase in RG values. There was no significant change concerning glycated hemoglobin and fasting glucose in the G1. Therefore, it can be concluded that there were improvements in periodontal parameters over the 12 months of research, but without changes in glycemic levels of diabetic patients. Thus, periodontal therapy proved effective in maintaining oral health.

Efeito do parceiro social sobre a resposta comportamental ao ambiente novo em sagüi comum (Callithrix jacchus)

Algumas pesquisas demonstram que a presença de um parceiro social durante uma situação de risco modula a resposta ao estresse, atenuando seus efeitos negativos. Neste estudo, 8 díades de machos e 8 de fêmeas de sagüi comum (Callithrix jacchus) foram expostos a um ambiente novo, sozinhos e acompanhados de um parceiro de mesmo sexo e idade. Quando submetidos a um ambiente novo em companhia de um animal de mesmo sexo, os machos apresentaram um perfil mais filiativo enquanto as fêmeas foram mais competitivas entre si. Os resultados mostram que a resposta comportamental é sexualmente dimórfica, e que machos e fêmeas utilizam diferentes estratégias quando confrontados com situações desafiadoras no ambiente natural Abstract Some researches demonstrate that the presence of a social partner during a challenging situation modulates the stress response, decreasing its negative effects. In this study common marmoset (Callithrix jacchus) males and females were exposed to a new environment, alone or in companion of a social partner of the same sex and age. When submitted to new environment in companion of a same-sex social partner males showed more affiliation whereas females performed agonistic behaviors. The results show that behavioral response is sexually dimorphic and that males and females used different strategies when facing challenging situations in natural conditions

Influência do vírus da hepatite G (GBV-C) na resposta imune frente à infecção por Leishmania chagasi

GB virus type C (GBV-C) appears to promote a Th1 response and is associated with prolonged survival in HIV-infected people. L. chagasi causes a spectrum of illness that varies from severe visceral leishmaniasis, a disease that in the majority of cases is fatal if not treated, to self resolution of infection and development of positive DTH response that is protective against symptomatic disease. To determine if GBV-C viremia might influence the outcome of Leishmania infection, we characterized GBV-C status in a cohort of subjects residing in a L. chagasi endemic area in Brazil. GBV-C viremia was more prevalent in blood donors from urban than in periurban regions of Natal, Brazil (16% and 7.5% respectively). Evidence of prior GBV-C (anti-E2 antibodies) was detected in 24% and 12%of these groups respectively. Anti-E2 increased with age (p= 0.0121). No difference in GBV-C viremia was found in the DTH+ and VL groups (p= 0.269); however, subjects with visceral leishmaniasis were more likely to have anti-E2 than DTH+ subjects (p=0.0012), and DTH induration was smaller in subjects with E2 antibodies (4.5 mm) compared those without (7.12 mm) (p= 0.002). Furthermore, the size of the Leishmania DTH response was greater in GBV-C viremica subjects (6.8 mm) compared to non-viremic subjects (3.3 mm; p= 0.0054). There findings suggest that GBV-C virus may promote a type 1 immune response that could influence the outcome of Leishmania infection

Resposta imune à saliva de flebotomíneos (diptera: psychodidae) em indivíduos residentes em áreas urbana e periurbana no nordeste do brasil

Visceral leishmaniasis (VL) has a wide geographical distribution in tropical and subtropical areas of the planet, which is a protozoan parasite of the genus Leishmania. This pathogen is transmitted to the host through the sandflies bite, with its saliva, the immune response that leads to both. In the state of Rio Grande do Norte, 85% of the sand flies captured is Lutzomyia longipalpis, but the second most abundant, Lutzomyia evandroi, it deserves emphasis because its wide distribution and eclectic behavior. The exposure of people living in endemic areas for the insect vector VL greatly increases the chances of infection. This study aimed to evaluate aspects of the epidemiological profile of VL in endemic areas of human and nonendemic in the metropolitan area of Natal, as well as verify the abundance and seasonal fluctuations of sandflies species in two counties endemic for VL. Were collected in the municipalities of Nísia Floresta, Parnamirim, São Gonçalo do Amarante and Macaíba, of which groups of females were separated for further dissection of the salivary glands and identification of species. The blood samples used were from individuals of two Natal s districts where it has never been reported cases of VL and neighborhoods of Parnamirim applicants who present cases of VL. In the municipality of Nísia Floresta, the most abundant species was L. evandroi with 38.39%, followed by L. longipalpis with 36.22%, L. walkeri 19.67% L. lenti 3.81%, L. wellcomei 1.39% and L. whitmani 0.52%. Already in Parnamirim the proportions were L. walkeri with 73.15%, L. evandroi with 10.55%, L. wellcomei 7.63%, L. longipalpis 6.37%, L. whitmani 1.46%, L. sordellii 0.52%, L. intermedia 0.21 and L. shanonni 0.1%. In both municipalities was observed higher abundance of species distributed in the initial months of the year, as February and March. The study showed that no difference in exposure to the vector of VL among individuals from endemic and non endemic area for this disease. But there are differences in exposure between individuals of L. longipalpis and L. evandroi, confirming the great powers of the first vector. It was also characterized as predominant phenotype in the population of endemic areas who had negative serologic responses to antigens of Leishmania and result in negative Montenegro skin test (DTH), indicating that much of the population hasn t been bitten by infected insects

Modulação da expressão da proteína XPA em resposta ao tratamento com azul de metileno fotossensibilizado

Reactive oxygen species (ROS) are produced by aerobic metabolism and react with biomolecules, such as lipids, proteins and DNA. In high concentration, they lead to oxidative stress. Among ROS, singlet oxygen (1O2) is one of the main ROS involved in oxidative stress and is one of the most reactive forms of molecular oxygen. The exposure of some dyes, such as methylene blue (MB) to light (MB+VL), is able to generate 1O2 and it is the principle involved in photodynamic therapy (PDT). 1O2 e other ROS have caused toxic and carcinogenic effects and have been associated with ageing, neurodegenerative diseases and cancer. Oxidative DNA damage is mainly repaired by base excision repair (BER) pathway. However, recent studies have observed the involvement of nucleotide excision repair (NER) factors in the repair of this type of injury. One of these factors is the Xeroderma Pigmentosum Complementation Group A (XPA) protein, which acts with other proteins in DNA damage recognition and in the recruitment of other repair factors. Moreover, oxidative agents such as 1O2 can induce gene expression. In this context, this study aimed at evaluating the response of XPA-deficient cells after treatment with photosensitized MB. For this purpose, we analyzed the cell viability and occurrence of oxidative DNA damage in cells lines proficient and deficient in XPA after treatment with MB+VL, and evaluated the expression of this enzyme in proficient and complemented cells. Our results indicate an increased resistance to treatment of complemented cells and a higher level of oxidative damage in the deficient cell lines. Furthermore, the treatment was able to modulate the XPA expression up to 24 hours later. These results indicate a direct evidence for the involvement of NER enzymes in the repair of oxidative damage. Besides, a better understanding of the effects of PDT on the induction of gene expression could be provided

Estado nutricional e efeito da vitamina A na resposta imune frente à infecção por Leishmania Infantum

Nutritional status is an important determinant to the response against Leishmania infection, although few studies have characterized the molecular basis for the association found between malnutrition and the disease. Vitamin A supplementation has long been used in developing countries to prevent mortality by diarrheal and respiratory diseases, but there are no studies on the role of vitamin A in Leishmania infection, although we and others have found vitamin A deficiency in visceral Leishmaniasis (VL). Regulatory T cells are induced in vitro by vitamin A metabolites and are considered important cells implicated T CD4+ cell suppression in human VL. This work aimed to examine the correlation of nutritional status and the effect of vitamin A in the response against Leishmania infantum infection. A total of 179 children were studied: 31 had active VL, 33 VL history, 44 were DTH+ and 71 were DTH- and had negative antibody to Leishmania (DTH-/Ac-). Peripheral blood monuclear cells were isolated in a subgroup of 10 active VL and 16 DTH-/Ac- children and cultivated for 20h under 5 different conditions: 1) Medium, 2) Soluble promastigote L. infantum antigens (SLA), 3) All-trans retinoic acid (ATRA), 4) SLA + ATRA and 5) Concanavalin A. T CD4+CD25highFoxp3+, T CD4+CD25-Foxp3- and CD14+ monocytes were stained and studied by flow cytometry for IL-10, TGF-β and IL-17 production. Nutritional status was compromised in VL children, which presented lower BMI/Age and retinol concentrations when compared to healthy controls. We found a negative correlation between nutritional status (measured by BMI/Age and serum retinol) and anti-Leishmania antibodies and acute phase proteins. There was no correlation between nutritional status and parasite load. ATRA presented a dual effect in Treg cells and monocytes: In healthy children (DTH-/Ac-), it induced a regulatory response, increasing IL-10 and TGF-β production; in VL children it modulated the immune response, preventing increased IL-10 production after SLA stimulation. Furthermore, we found a positive correlation between BMI/Age and IL-17 production and negative correlation between serum retinol and IL-10 and TGF-β production in T CD4+CD25highFoxp3+ cells after SLA stimulus. Our results show a potential dual role of vitamin A in the immune system: improvement of regulatory profile during homeostasis and down modulation of IL-10 in Treg cells and monocytes during symptomatic VL. Therefore, the use of vitamin A concomitant to VL therapy might improve recovery from disease status in Leishmania infantum infection

O papel modulatório do ferro sobre a resposta imune na Leishmaniose Visceral

Iron is an essential element for many cellular functions, including the immune response against intracellular pathogens. In this study, we aimed evaluate the effect of iron on IRP2, IFN-γ, TNF-α, IL-6, IL-10, MIG and IP10 expression in PBMC and assess the effect of the spleen parasite load on the expression of these genes in the spleen of L. infantum naturally infected dogs. Blood sample from 7 DTH+ donor was collected and PBMC was obtained. The cells were cultivated in absence (iron chelator desferroximane, DFO 10 μM supplemented media) or in presence of iron (hemin 6 mM) for 1 h, followed by stimulation with Leishmania infatum antigen for 4 h. 44 dog spleen samples were obtained and parasite load in this organ was determinate by qPCR. Gene expression was analyzed by qPCR and cytokine production quantified by flow cytometry. In antigen stimulated cells, genes involved in immune response are significantly more expressed in presence of iron. T CD4+ and TCD8+ lymphocytes produces IFN-γ, TNF-α and IL-10 possibly in iron dependent pathway. Monocytes antigen stimulated reduced TNF-α, IL-6 and IL-10 production in presence of iron. We found spleen of infected dogs IRP2 expression increases according to parasite load in that organ, while an inverse profile was found for IFN-γ, TNF-α e IL-10 expression. These results suggest that T lymphocytes depends on iron to produce IFN-γ, TNF-α and IL-10, while iron seems to inhibit cytokine production in monocytes. So, we propose an immunoregulatory mechanism carried out by iron during L. infantum infection in humans and dogs

Resposta de Chromobacterium Violaceum cultivada em alta concentração de ferro

The Chromobacterium violaceum is a β-proteobacterium Gram-negative widely found in tropical and subtropical regions, whose genome was sequenced in 2003 showing great metabolic versatility and biotechnological and pharmaceutical potential. Given the large number of ORFs related to iron metabolism described in the genome of C. violaceum, the importance of this metal for various biological processes and due to lack of data about the consequences of excess of iron in free-living organisms, it is important to study the response mechanism of this bacterium in a culture filled with iron. Previous work showed that C. violaceum is resistant to high concentrations of this metal, but has not yet been described the mechanism which is used to this survival. Thus, to elucidate the response of C. violaceum cultured in high concentrations of iron and expecting to obtain candidate genes for use in bioremediation processes, this study used a shotgun proteomics approach and systems biology to assess the response of C. violaceum grown in the presence and absence of 9 mM of iron. The analysis identified 531 proteins, being 71 exclusively expressed by the bacteria grown in the presence of the metal and 100 just in the control condition. The increase in expression of proteins related to the TCA cycle possibly represents a metabolic reprogramming of the bacteria caused by high concentration of iron in the medium. Moreover, we observed an increase in the activity assay of superoxide dismutase and catalase as well as in Total Antioxidant Activity assay, suggesting that the metal is inducing oxidative stress in C. violaceum that increases the levels of violacein and antioxidant enzymes to better adapt to the emerging conditions. Are also part of the adaptive response changes in expression of proteins related to transport, including iron, as well as an increased expression of proteins related to chemotaxis response, which would lead the bacteria to change the direction of its movement away from the metal. Systems Biology results, also suggest a metabolic reprogramming with mechanisms coordinated by bottleneck proteins involved in transcription (GreA), energy metabolism (Rpe and TpiA) and methylation (AhcY)

Identificação de genes em Chromobacterium violaceum relacionados à resposta ao estresse

The sequencing of the genome of Chromobacterium violaceum identified one single circular chromosome of 4.8 Mb, in which approximately 40% of the founded ORFs are classified as hypothetical conserved or hypothetical. Some genic regions of biotechnological and biological interest had been characterized, e. g., environmental detoxification and DNA repair genes, respectively. Given this fact, the aim of this work was to identify genes of C. violaceum related to stress response, as the ones involved with mechanisms of DNA repair and/or genomic integrity maintenance. For this, a genomic library of C. violaceum was built in Escherichia coli strain DH10B (RecA-), in which clones were tested to UVC resistance, resulting in five candidates clones. In the PLH6A clone were identified four ORFs (CV_3721 to 3724). Two ORFs, CV_3722 and CV_3724, were subcloned and a synergic complementation activity was observed. The occurrence of an operon was confirmed using cDNA from C. violaceum in a RT-PCR assay. Further, it was observed the induction of the operon after the treatment with UVC. Thus, this operon was related to the stress response in C. violaceum. The mutagenesis assay with rifampicin after the treatment with UVC light showed high frequency of mutagenicity for the ORF CV_3722 (Pol III δ subunit). In this way, we propose that the C. violaceum δ subunit can act in DH10B in the translesion synthesis using Pol IV in a RecA independent-manner pathway. In growth curve assays other four clones (PLE1G, PLE7B, PLE10B and PLE12H) were able to complement the function at the dose 5 J/m2 and in mutagenicity assays PLE7B, PLE10B and PLE12H showed frequencies of mutation with significant differences upon the control (DH10B), demonstrating that in some way they are involved with the stress response in C. violaceum. These clones appear to be interrelated, probably regulated by a messenger molecule (eg., nucleotide c-di-GMP) and/or global regulatory molecule (eg., σS subunit of RNA polymerase).The results obtained contribute for a better genetic knowledge of this specie and its response mechanisms to environmental stress.

Proteômica diferencial da Chromobacterium violaceum em resposta ao estresse oxidativo induzido por peróxido de hidrogênio

The β-proteobacterium Chromobacterium violaceum is a Gram-negative, free-living, saprophytic and opportunistic pathogen that inhabits tropical and subtropical ecosystems among them, in soil and water of the Amazon. It has great biotechnological potential, and because of this potential, its genome was completely sequenced in 2003. Genome analysis showed that this bacterium has several genes with functions related to the ability to survive under different kinds of environmental stresses. In order to understand the physiological response of C. violaceum under oxidative stress, we applied the tool of shotgun proteomics. Thus, colonies of C. violaceum ATCC 12472 were grown in the presence and absence of 8 mM H2O2 for two hours, total proteins were extracted from bacteria, subjected to SDS-PAGE, stained and hydrolysed. The tryptic peptides generated were subjected to a linear-liquid chromatography (LC) followed by mass spectrometer (LTQ-XL-Orbitrap) to obtain quantitative and qualitative data. A shotgun proteomics allows to compare directly in complex samples, differential expression of proteins and found that in C. Violaceum, 131 proteins are expressed exclusively in the control condition, 177 proteins began to be expressed under oxidative stress and 1175 proteins have expression in both conditions. The results showed that, under the condition of oxidative stress, this bacterium changes its metabolism by increasing the expression of proteins capable of combating oxidative stress and decreasing the expression of proteins related processes bacterial growth and catabolism (transcription, translation, carbon metabolism and fatty acids). A tool with of proteomics as an approach of integrative biology provided an overview of the metabolic pathways involved in the response of C. violaceum to oxidative stress, as well as significantly amplified understanding physiological response to environmental stress. Biochemical and "in silico" assays with the hypothetical ORF CV_0868 found that this is part of an operon. Phylogenetic analysis of superoxide dismutase, protein belonging to the operon also showed that the gene is duplicated in genome of C. violaceum and the second copy was acquired through a horizontal transfer event. Possibly, not only the SOD gene but also all genes comprising this operon were obtained in the same manner. It was concluded that C. violaceum has complex, efficient and versatile mechanisms in oxidative stress response