RESUMEN
K. pneumoniae BLh-1 strain was genetically modified aiming at obtaining high ethanol productivity in cultivations using residual glycerol from biodiesel synthesis as substrate. The recombinant strain K. pneumoniae Kp17 was obtained by inserting the multicopy plasmid pTOPOBL17 containing the AdhE gene, and its own promoter, from K. pneumoniae BLh-1. Influence of Fe2+ supplementation and initial glycerol concentration on culture conditions were analyzed, both in rotatory shaker and in batch bioreactors. In the bioreactor cultures, K. pneumoniae Kp17 strain produced 4.5 g L-1 of ethanol (productivity of 0.50 g L-1 h-1 and yields of 0.15 g g-1) after 24-h cultivation, corresponding to an increase of approximately 40% in ethanol concentration compared to wild strain, K. pneumoniae BLh-1. Best conditions were then applied in exponential fed-batch bioreactors, with final ethanol concentration of 17.30 g L-1 (productivity of 0.59 g L-1 h-1 and yields of 0.16 g g-1) after 30 h of feeding, representing 11.5% of increment in titer of ethanol compared to the wild strain. Mutant cells kept 92.5% of the plasmids under batch in 24 h, and 71.9% under fed-batch after 27 h of exponential feeding. The findings in this work show the possibility of using a simple approach to genetically modify K. pneumoniae to be employed this versatile bacterium for the bioconversion of residual glycerol into ethanol.
Asunto(s)
Técnicas de Cultivo Celular por Lotes , ADN Recombinante/genética , Etanol/metabolismo , Glicerol/metabolismo , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/metabolismo , Biotecnología , Biotransformación , Cinética , Klebsiella pneumoniae/crecimiento & desarrolloRESUMEN
Aim. This study aimed to assess the antioxidant activity of quercetin (Q) in an experimental model of cirrhosis induced by CCl(4) inhalation. Materials and Methods. We used 25 male Wistar rats (250 g) that were divided into 3 groups: control (CO), CCl(4), and CCl(4) + Q. The rats were subjected to CCl(4) inhalation (2x/week) for 16 weeks, and they received phenobarbital in their drinking water at a dose of 0.3 g/dL as a P450 enzyme inducer. Q (50 mg/Kg) was initiated intraperitoneally at 10 weeks of inhalation and lasted until the end of the experiment. Statistical analysis was by ANOVA Student Newman-Keuls (mean ± SEM), and differences were considered statistically significant when P < 0.05. Results. After treatment with quercetin, we observed an improvement in liver complications, decreased fibrosis, as analyzed by picrosirius for the quantification of collagen, and decreased levels of matrix metalloproteinase 2 (MMP-2) compared with the CCl(4) group. It also reduced oxidative stress, as confirmed by the decrease of substances reacting to thiobarbituric acid (TBARS), the increased activity of antioxidant enzymes, and the reduced glutathione ratio and glutathione disulfide (GSH/GSSG). Conclusion. We suggest that the use of quercetin might be promising as an antioxidant therapy in liver fibrosis.
RESUMEN
In hepatic toxicity induced in rats by two injections of thioacetamide (TAA, 350 mg/kg with an interval of 8 hr), the action of quercetin was investigated. After 96 hr, TAA administration resulted in hepatic necrosis, significant increases in serum transaminase activity, and increases in hepatic lipoperoxidation. Thioacetamide-induced hepatotoxicity also showed changes in antioxidant enzymes in the liver of rats, with alterations in p-ERK 1/2 (phosphorylated extracellular-signal related kinase 1/2) as well as an imbalance between proapototic protein Bax and anti-apoptotic protein Bcl-2 expression. With administration of the flavonoid quercetin (50 mg/Kg i.p.) for four consecutive days following TAA, serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activity were close to normal values in rats. Histological findings suggested that quercetin had a preventive effect on TAA-induced hepatic necrosis. Quercetin treatment caused significant decreases in lipid peroxide levels in the TAA-treated rats, with some changes in antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Quercetin also inhibited the change of the p-ERK1/2 by TAA and significantly prevented the increase in Bax/Bcl-2 ratio, thus preventing apoptosis. Findings indicate that quercetin may have a preventive effect on TAA-induced hepatotoxicity by modulating the oxidative stress parameters and apoptosis pathway.
Asunto(s)
Antioxidantes/farmacología , Enfermedad Hepática Inducida por Sustancias y Drogas/tratamiento farmacológico , Quercetina/farmacología , Tioacetamida/toxicidad , Alanina Transaminasa/sangre , Animales , Apoptosis/efectos de los fármacos , Proteínas Reguladoras de la Apoptosis/metabolismo , Aspartato Aminotransferasas/sangre , Western Blotting , Catalasa/metabolismo , Enfermedad Hepática Inducida por Sustancias y Drogas/patología , Enfermedad Hepática Inducida por Sustancias y Drogas/prevención & control , Relación Dosis-Respuesta a Droga , Regulación de la Expresión Génica , Glutatión Peroxidasa/metabolismo , Peroxidación de Lípido/efectos de los fármacos , Peróxidos Lipídicos/análisis , Sistema de Señalización de MAP Quinasas/genética , Masculino , Estrés Oxidativo , Fosforilación , Ratas , Ratas Wistar , Superóxido Dismutasa/metabolismo , Proteína X Asociada a bcl-2/genética , Proteína X Asociada a bcl-2/metabolismoRESUMEN
Omega-3 polyunsaturated fatty acids (omega-3 PUFAs) have been widely associated to beneficial effects over different neuropathologies, but only a few studies associate them to Parkinson's disease (PD). Rats were submitted to chronic supplementation (21-90 days of life) with fish oil, rich in omega-3 PUFAs, and were uni- or bilaterally lesioned with 4microg of the neurotoxin 6-hydroxydopamine (6-OHDA) in the medial forebrain bundle. Although lipid incorporation was evidenced in neuronal membranes, it was not sufficient to compensate motor deficits induced by 6-OHDA. In contrast, omega-3 PUFAs were capable of reducing rotational behavior induced by apomorphine, suggesting neuroprotection over dyskinesia. The beneficial effects of omega-3 PUFAs were also evident in the maintenance of thiobarbituric acid reactive substances index from animals lesioned with 6-OHDA similar to levels from SHAM and intact animals. Although omega-3 PUFAs did not modify the tyrosine hydroxylase immunoreactivity in the substantia nigra pars compacta and in the ventral tegmental area, nor the depletion of dopamine (DA) and its metabolites in the striatum, DA turnover was increased after omega-3 PUFAs chronic supplementation. Therefore, it is proposed that omega-3 PUFAs action characterizes the adaptation of remaining neurons activity, altering striatal DA turnover without modifying the estimated neuronal population.
Asunto(s)
Encéfalo/metabolismo , Ácidos Grasos Omega-3/uso terapéutico , Actividad Motora , Trastornos Parkinsonianos/dietoterapia , Trastornos Parkinsonianos/metabolismo , Animales , Apomorfina/farmacología , Encéfalo/efectos de los fármacos , Encéfalo/enzimología , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Modelos Animales de Enfermedad , Dopamina/metabolismo , Agonistas de Dopamina/farmacología , Ácidos Grasos Omega-3/administración & dosificación , Peroxidación de Lípido , Masculino , Actividad Motora/efectos de los fármacos , Neuronas/efectos de los fármacos , Neuronas/enzimología , Neuronas/metabolismo , Oxidopamina , Trastornos Parkinsonianos/inducido químicamente , Distribución Aleatoria , Ratas , Ratas Wistar , Sustancias Reactivas al Ácido Tiobarbitúrico/metabolismo , Resultado del Tratamiento , Tirosina 3-Monooxigenasa/metabolismoRESUMEN
The main goal of this study is to alert researchers who work with cell cultures for the risk of contamination by structures called nanobacteria (NB). NB are tiny structures with size varying from 80 to 500 nm, commonly occurring in clusters and producing a biofilm which contains carbonate or hydroxyl apatite. The most likely source of cell culture contamination by such organisms is serum used as supplement in culture media. The presence of NB leads to a progressive culture deterioration with accumulation of granules (probably phagocytized NB) in cytoplasmic vacuoles, an increasing number of dead cells in the supernatant and degeneration of cells that remained attached to the bottom of the vessel. NB can also be found in culture supernatants where they are found in clusters with variable size and displaying brownian movement. In this study, 19 cell lineages, 8 batches of sera and 1 batch of growth supplement from different sources were analyzed. Samples from sera were cultured in Eagle's Minimum Essential Medium (E-MEM) or incubated directly at 37ºC. Tests carried out to detect the presence of extracellular bacteria, Mycoplasma sp and viruses were all negative. Analysis by scanning electron microscopy (SEM) revealed tiny oval structures less than 500 nm in size, isolated or in small groups, in all material analyzed except in one fetal bovine serum batch.
O principal objetivo deste estudo é alertar aos pesquisadores que trabalham com cultivos celulares sobre o risco de contaminação por estruturas denominadas nanobactérias (NB). NB são estruturas muito pequenas cujo tamanho varia de 80 a 500 nm e que comumente ocorrem em agrupamentos, produzindo biofilme de carbonato ou hidroxiapatita. A fonte mais provável de contaminação dos cultivos celulares por tais organismos é o soro utilizado como suplemento nos meios de cultura. A presença de NB leva a uma progressiva deterioração do cultivo com acúmulo de grânulos (provavelmente NB fagocitadas) em vacúolos citoplasmáticos, um número cada vez maior de células mortas no sobrenadante e degeneração das células que permaneceram aderidas à superfície do frasco de cultura. NB podem ser encontradas também em sobrenadantes de cultivos onde são observadas em agrupamentos de tamanho variável com movimento browniano. Neste estudo, 19 linhagens celulares, 8 lotes de soro e 1 lote de suplemento de diferentes procedências foram analisados. Amostras de soros foram cultivadas em Meio Essencial Mínimo de Eagle (E-MEM) ou incubados diretamente a 37ºC. Testes efetuados para detectar a presença de bactérias extracelulares, Mycoplasma sp e vírus foram todos negativos. Análise por microscopia eletrônica de varredura (SEM) revelou minúsculas estruturas ovóides com tamanho inferior a 500 nm, isoladas ou em pequenos agrupamentos, em todos os materiais analisados exceto em um lote de soro fetal bovino.