Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 8.402
Filtrar
1.
J Basic Microbiol ; 60(1): 47-57, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31680284

RESUMO

The present investigation deals with the characterisation of three As-resistant bacteria, Bacillus aryabhattai strain VPS1, Bacillus licheniformis strain VPS6 and Sporosarcina thermotolerans strain VPS7 isolated from the rhizosphere of a contaminated paddy field in Chakdaha, Nadia, West Bengal, India. Two strains, VPS6 and VPS7 showed ureolytic activity, which can be used for microbial-induced calcite precipitation of As as a bioremediation option. However, As reduction and oxidation capacities were not reported in any of these bacteria. A phylogenetic tree of 16S ribosomal RNA gene sequences was constructed for all three bacterial isolates, including different species of As-resistant Bacillus and Sporosarcina. Furthermore, literature survey and genome mining were employed to explore the diversity of As resistance-related proteins, arsenite S-adenosylmethyltransferase (ArsM) and arsenical pump membrane protein (ArsB) among different bacteria, and the phylogenetic relatedness was studied to understand the distribution and evolution of their amino acid sequences. ArsB was predominantly present in a wide variety of bacteria (347 taxa); however, ArsM was reported in comparatively fewer isolates (109 taxa). There were a total of 60 similar taxa that contained both ArsM and ArsB. Both proteins were most abundantly present in phylum Proteobacteria. Overall, this investigation enumerates As-resistant bacteria to understand the As metabolism in the environment, and the phylogenetic analysis of As resistance-related proteins helps in understanding the functional relationship in different bacteria for their role in As mobility in the environment.


Assuntos
Arsenicais/metabolismo , Bactérias/metabolismo , Proteínas de Bactérias/genética , Farmacorresistência Bacteriana/genética , Poluentes do Solo/metabolismo , Bacillus/genética , Bacillus/metabolismo , Bacillus licheniformis/genética , Bacillus licheniformis/metabolismo , Bactérias/classificação , Bactérias/genética , Biodegradação Ambiental , Índia , Filogenia , RNA Ribossômico 16S/genética , Rizosfera , Microbiologia do Solo , Sporosarcina/genética , Sporosarcina/metabolismo , Ureia/metabolismo
2.
Chemosphere ; 241: 125083, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31683425

RESUMO

The increasing inflow of nitrogen (N) substrates into marine nearshore ecosystems induces proliferation of harmful algal blooms (HABs) of dinoflagellates, such as potentially toxic invasive species Prorocentrum minimum. In this study, we estimated the influence of NO3-, NH4+ and urea on transcription levels and urea transporter dur3 and nitrate transporter nrt2 genes expression in these dinoflagellates. We identified dur3 and nrt2 genes sequences in unannotated transcriptomes of P. minimum and other dinoflagellates presented in MMETSP database. Phylogenetic analysis showed that these genes of dinoflagellates clustered to the distinct clade demonstrating evolutionary relationship with the other known dur3 and nrt2 genes of microalgae. The evaluation of expression levels of dur3 and nrt2 genes by RT-qPCR revealed their sensitivity to input of the studied N sources. Dur3 expression levels were downregulated after the supplementation of additional N sources and were 1.7-2.6-fold lower than in the nitrate-grown culture. Nrt2 expression levels decreased 1.9-fold in the presence of NH4+. We estimated total RNA and DNA synthesis rates by the analysis of incorporation of 3H-thymidine and 3H-uridine in batch and continuous cultures. Addition of N compounds did not affect the DNA synthesis rates. Transcription levels increased up to 12.5-fold after the N supplementation in urea-limited treatments. Investigation of various nitrogen sources as biomarkers of dinoflagellate proliferation due to their differentiated impact on expression of dur3 and nrt2 genes and transcription rates in P. minimum cells allowed concluding about high potential of the studied parameters for future modeling of HABs under global N pollution.


Assuntos
Dinoflagelados/genética , Nitrogênio/metabolismo , Proteínas de Transporte de Ânions , Dinoflagelados/metabolismo , Ecossistema , Proliferação Nociva de Algas/fisiologia , Proteínas de Membrana Transportadoras , Nitratos/metabolismo , Filogenia , Ureia/metabolismo
3.
J Forensic Sci ; 65(1): 128-133, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31365136

RESUMO

Urea, uric acid, and creatinine have been demonstrated to be relatively stable in postmortem blood (BL), thus being useful for diagnostic purposes. However, no studies have explored their levels in BL, vitreous humor (VH), and synovial fluid (SF) concurrently. Therefore, we measured and compared their levels in these fluids. We also determined the effects of various factors on their levels. The results indicated that BL urea, uric acid, and creatinine levels were significantly higher than VH and SF levels. VH and SF urea levels and SF creatinine levels had a strong correlation with BL urea and creatinine levels, respectively. BL creatinine levels were higher in men than in women. BL and SF creatinine levels were negatively correlated with age. SF uric acid and BL, VH, and SF creatinine levels exhibited a positive correlation with weight. Only VH creatinine levels were positively correlated with body mass index. None of urea, uric acid, and creatinine levels were correlated with postmortem interval.


Assuntos
Creatinina/metabolismo , Líquido Sinovial/metabolismo , Ureia/metabolismo , Ácido Úrico/metabolismo , Corpo Vítreo/metabolismo , Adolescente , Adulto , Idoso , Peso Corporal , Estudos de Coortes , Feminino , Medicina Legal , Humanos , Modelos Lineares , Masculino , Pessoa de Meia-Idade , Fatores Sexuais , Adulto Jovem
4.
Yakugaku Zasshi ; 139(12): 1509-1512, 2019.
Artigo em Japonês | MEDLINE | ID: mdl-31787637

RESUMO

Human induced pluripotent stem (iPS) cell-derived hepatocyte-like cells (iPS-HLCs) are expected to be applicable to large-scale in vitro hepatotoxicity screening systems. Accordingly, methods for generating HLCs from human iPS cells have been improved over the past decade. However, although human hepatocytes have zone-specific characteristics in vivo, there is currently no technique to generate zone-specific HLCs from human iPS cells. Therefore, to generate HLCs with zone-specific properties from human iPS cells, we cultured iPS-HLCs using a parenchymal or nonparenchymal cell-conditioned medium (CM). The results showed that urea production and gluconeogenesis capacity in iPS-HLCs were increased by culturing with cholangiocyte-CM, and glutamine production and drug metabolism capacity in iPS-HLCs were increased by culturing with hepatocyte-CM. It was thus clarified that iPS-HLCs acquire zone 1 hepatocyte-like properties by culturing with cholangiocyte-CM and that iPS-HLCs acquire zone 3 hepatocyte-like properties by culturing with hepatocyte-CM. In addition, we found that WNT inhibitory factor-1 secreted from cholangiocytes, and WNT7B and WNT8B secreted from hepatocytes play important roles in the zone-specific conversion of iPS-HLCs. We hope that our findings will facilitate the application of iPS-HLCs to drug discovery research.


Assuntos
Doença Hepática Induzida por Substâncias e Drogas , Descoberta de Drogas , Hepatócitos , Células-Tronco Pluripotentes Induzidas , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Sistema Biliar/citologia , Sistema Biliar/metabolismo , Técnicas de Cultura de Células , Meios de Cultura , Gluconeogênese , Hepatócitos/metabolismo , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Ureia/metabolismo , Proteínas Wnt/metabolismo
5.
Immunity ; 51(6): 1074-1087.e9, 2019 12 17.
Artigo em Inglês | MEDLINE | ID: mdl-31784108

RESUMO

Infections induce complex host responses linked to antiviral defense, inflammation, and tissue damage and repair. We hypothesized that the liver, as a central metabolic hub, may orchestrate systemic metabolic changes during infection. We infected mice with chronic lymphocytic choriomeningitis virus (LCMV), performed RNA sequencing and proteomics of liver tissue, and integrated these data with serum metabolomics at different infection phases. Widespread reprogramming of liver metabolism occurred early after infection, correlating with type I interferon (IFN-I) responses. Viral infection induced metabolic alterations of the liver that depended on the interferon alpha/beta receptor (IFNAR1). Hepatocyte-intrinsic IFNAR1 repressed the transcription of metabolic genes, including Otc and Ass1, which encode urea cycle enzymes. This led to decreased arginine and increased ornithine concentrations in the circulation, resulting in suppressed virus-specific CD8+ T cell responses and ameliorated liver pathology. These findings establish IFN-I-induced modulation of hepatic metabolism and the urea cycle as an endogenous mechanism of immunoregulation. VIDEO ABSTRACT.


Assuntos
Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Interferon Tipo I/imunologia , Fígado/metabolismo , Vírus da Coriomeningite Linfocítica/imunologia , Receptor de Interferon alfa e beta/metabolismo , Animais , Arginina/sangue , Linhagem Celular , Cricetinae , Feminino , Hepatócitos/metabolismo , Fígado/imunologia , Fígado/virologia , Coriomeningite Linfocítica/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Ornitina/sangue , Ornitina Carbamoiltransferase/genética , Transdução de Sinais/imunologia , Ureia/metabolismo , Células Vero
6.
Chem Commun (Camb) ; 55(94): 14119-14122, 2019 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-31687686

RESUMO

A new strategy to construct a transient supramolecular peptide amphiphile (SPA) and its vesicular aggregates is displayed. The construction of the amphiphile is assisted by the ternary complexation of cucurbit[8]uril and pH responsive imine bond formation. The transient assembly follows a pH clock set by urea/urease and hydrolysis of glucono delta-lactone (GdL). The transient assembly can be repeated for several cycles through feeding the system with the fuel (urea).


Assuntos
Peptídeos/química , Tensoativos/química , Concentração de Íons de Hidrogênio , Hidrólise , Lactonas/química , Lactonas/metabolismo , Substâncias Macromoleculares/síntese química , Substâncias Macromoleculares/química , Estrutura Molecular , Peptídeos/síntese química , Tensoativos/síntese química , Ureia/química , Ureia/metabolismo , Urease/química , Urease/metabolismo
7.
Phys Rev Lett ; 123(12): 128101, 2019 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-31633990

RESUMO

Recent experimental results have shown that enzymes can diffuse faster when they are in the presence of their reactants (substrate). This faster diffusion has been termed enhanced diffusion. Fluorescence correlation spectroscopy (FCS), which has been employed as the only method to make these measurements, relies on analyzing the fluctuations in fluorescence intensity to measure the diffusion coefficient of particles. Recently, artifacts in FCS measurements due to its sensitivity to environmental conditions have been evaluated, calling prior enhanced diffusion results into question. It behooves us to adopt complementary and direct methods to measure the mobility of enzymes. Herein, we use a technique of direct single molecule imaging to observe the diffusion of individual enzymes in solution. This technique is less sensitive to intensity fluctuations and deduces the diffusion coefficient directly based on the trajectory of the enzyme. Our measurements recapitulate that enzyme diffusion is enhanced in the presence of its substrate and find that the relative increase in diffusion of a single enzyme is even higher than those previously reported using FCS. We also use this complementary method to test if the total enzyme concentration affects the relative increase in diffusion and if the enzyme oligomerization state changes during its catalytic turnover. We find that the diffusion increase is independent of the total concentration of enzymes and the presence of substrate does not change the oligomerization state of enzymes.


Assuntos
Enzimas/metabolismo , Imagem Molecular/métodos , Difusão , Enzimas/química , Proteínas de Fluorescência Verde/química , Proteínas de Fluorescência Verde/metabolismo , Cinética , Espectrometria de Fluorescência/métodos , Ureia/metabolismo , Urease/química , Urease/metabolismo
8.
J Agric Food Chem ; 67(42): 11584-11590, 2019 Oct 23.
Artigo em Inglês | MEDLINE | ID: mdl-31566380

RESUMO

Ureolytic microbes play a pivotal role in the maintenance of soil fertility. Soil aggregates are supposed to provide heterogeneous habitats for microorganisms, which may result in distinct metabolic functions. However, limited information is available regarding the distribution patterns, driving factors, and activity of ureolytic microbiota at the aggregate scale. In this study, we characterized the ureolytic microbiota and urease activity of three soil aggregate fractions from an Inceptisol subjected to 5 years of different fertilization regimes. Correlations between soil chemical characteristics and ureolytic microbial communities were analyzed. The results showed that the total abundance as well as the relative abundance of copiotrophic ureolytic microbes generally increased with the increasing soil aggregate size. This trend was in line with the nutrient distribution patterns, including labile carbon, NH4+, total carbon, nitrogen, and phosphorus. Soil urease activity also increased significantly with the increasing soil aggregate size and was positively correlated with copiotrophic ureolyric microbes, such as Betaproteobacteria, Alphaproteobacteria, and Gammaproteobacteria. Thus, we speculated that larger size soil aggregates with greater availability of labile carbon support more copiotrophic ureolyric microbes with a high growth rate, leading to a high density of total ureolytic microbes and higher urease activity. Smaller aggregates with less available carbon were associated with more oligotrophs, higher abundances of total ureolytic microbes, and higher urease activity. Our results suggest that larger soil aggregates and associated ureolyric microbes play a more important role in nutrient cycling for crop growth in this Inceptisol ecosystem.


Assuntos
Bactérias/enzimologia , Proteínas de Bactérias/metabolismo , Microbiologia do Solo , Solo/química , Ureia/metabolismo , Urease/metabolismo , Bactérias/genética , Bactérias/isolamento & purificação , Bactérias/metabolismo , Microbiota , Nitrogênio/metabolismo , Tamanho da Partícula , Fósforo/metabolismo
9.
Syst Appl Microbiol ; 42(6): 126021, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31623889

RESUMO

During long-term extra-terrestrial missions, food is limited and waste is generated. By recycling valuable nutrients from this waste via regenerative life support systems, food can be produced in space. Astronauts' urine can, for instance, be nitrified by micro-organisms into a liquid nitrate fertilizer for plant growth in space. Due to stringent conditions in space, microbial communities need to be be defined (gnotobiotic); therefore, synthetic rather than mixed microbial communities are preferred. For urine nitrification, synthetic communities face challenges, such as from salinity, ureolysis, and organics. In this study, a synthetic microbial community containing an AOB (Nitrosomonas europaea), NOB (Nitrobacter winogradskyi), and three ureolytic heterotrophs (Pseudomonas fluorescens, Acidovorax delafieldii, and Delftia acidovorans) was compiled and evaluated for these challenges. In reactor 1, salt adaptation of the ammonium-fed AOB and NOB co-culture was possible up to 45mScm-1, which resembled undiluted nitrified urine, while maintaining a 44±10mgNH4+-NL-1d-1 removal rate. In reactor 2, the nitrifiers and ureolytic heterotrophs were fed with urine and achieved a 15±6mg NO3--NL-1d-1 production rate for 1% and 10% synthetic and fresh real urine, respectively. Batch activity tests with this community using fresh real urine even reached 29±3mgNL-1d-1. Organics removal in the reactor (69±15%) should be optimized to generate a nitrate fertilizer for future space applications.


Assuntos
Reatores Biológicos/microbiologia , Microbiota , Nitrificação , Urina/química , Eliminação de Resíduos Líquidos/métodos , Amônia/metabolismo , Comamonadaceae/metabolismo , Delftia acidovorans/metabolismo , Nitritos/metabolismo , Nitrobacter/metabolismo , Nitrosomonas europaea/metabolismo , Pseudomonas fluorescens/metabolismo , Ureia/metabolismo
10.
Aquat Toxicol ; 216: 105294, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31585273

RESUMO

Many ecologically important fishes, including mahi-mahi (Coryphaena hippurus), and their offspring were directly exposed to crude oil following the Deepwater Horizon (DWH) oil spill. Early life stage fish are especially vulnerable to the toxicity of crude oil-derived polycyclic aromatic hydrocarbons (PAHs). In teleosts, yolk sac proteins are the main energy source during development and are usually catabolized into ammonia or urea among other byproducts. Although excretion of these waste products is sensitive to oil exposure, we know little about the underlying mechanisms of this process. In this study, we examined the effects of crude oil on ammonia and urea handling in the early life stages of mahi. Mahi embryos exposed to 30-32 µg L-1 ∑PAH exhibited increased urea excretion rates and greater accumulation of urea in the tissues before hatch suggesting that ammonia, which is highly toxic, was converted into less-toxic urea. Oil-exposed embryos (6.3-32 µg L-1 ∑PAH) displayed significantly increased tissue ammonia levels at 42 hpf and upregulated mRNA levels of ammonia transporters (Rhag, Rhbg and Rhcg1) from 30 to 54 hpf. However, despite increased accumulation and higher expression of ammonia transporters, the larvae exposed to higher ∑PAH (30 µg L-1 ∑PAH) showed reduced ammonia excretion rates after hatch. Together, the increased production of nitrogenous waste reinforces previous work that increased energy demand in oil-exposed embryos is fueled, at least in part, by protein metabolism and that urea synthesis plays a role in ammonia detoxification in oil-exposed mahi embryos. To our knowledge, this study is the first to combine physiological and molecular approaches to assess the impact of crude-oil on both nitrogenous waste excretion and accumulation in the early life stages of any teleosts.


Assuntos
Amônia/metabolismo , Estágios do Ciclo de Vida/efeitos dos fármacos , Perciformes/crescimento & desenvolvimento , Perciformes/metabolismo , Poluição por Petróleo/análise , Petróleo/toxicidade , Ureia/metabolismo , Animais , Proteínas de Peixes/genética , Proteínas de Peixes/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Larva/efeitos dos fármacos , Perciformes/genética , Hidrocarbonetos Policíclicos Aromáticos/toxicidade , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Poluentes Químicos da Água/toxicidade
11.
Theor Biol Med Model ; 16(1): 11, 2019 07 31.
Artigo em Inglês | MEDLINE | ID: mdl-31366360

RESUMO

BACKGROUND: After proteolysis, the majority of released amino acids from dietary protein are transported to the liver for gluconeogenesis or to peripheral tissues where they are used for protein synthesis and eventually catabolized, producing ammonia as a byproduct. High ammonia levels in the brain are a major contributor to the decreased neural function that occurs in several pathological conditions such as hepatic encephalopathy when liver urea cycle function is compromised. Therefore, it is important to gain a deeper understanding of human ammonia metabolism. The objective of this study was to predict changes in blood ammonia levels resulting from alterations in dietary protein intake, from liver disease, or from partial loss of urea cycle function. METHODS: A simple mathematical model was created using MATLAB SimBiology and data from published studies. Simulations were performed and results analyzed to determine steady state changes in ammonia levels resulting from varying dietary protein intake and varying liver enzyme activity levels to simulate liver disease. As a toxicity reference, viability was measured in SH-SY5Y neuroblastoma cells following differentiation and ammonium chloride treatment. RESULTS: Results from control simulations yielded steady state blood ammonia levels within normal physiological limits. Increasing dietary protein intake by 72% resulted in a 59% increase in blood ammonia levels. Simulations of liver cirrhosis increased blood ammonia levels by 41 to 130% depending upon the level of dietary protein intake. Simulations of heterozygous individuals carrying a loss of function allele of the urea cycle carbamoyl phosphate synthetase I (CPS1) gene resulted in more than a tripling of blood ammonia levels (from roughly 18 to 60 µM depending on dietary protein intake). The viability of differentiated SH-SY5Y cells was decreased by 14% by the addition of a slightly higher amount of ammonium chloride (90 µM). CONCLUSIONS: Data from the model suggest decreasing protein consumption may be one simple strategy to decrease blood ammonia levels and minimize the risk of developing hepatic encephalopathy for many liver disease patients. In addition, the model suggests subjects who are known carriers of disease-causing CPS1 alleles may benefit from monitoring blood ammonia levels and limiting the level of protein intake if ammonia levels are high.


Assuntos
Amônia/metabolismo , Dieta Rica em Proteínas/efeitos adversos , Hepatopatias/etiologia , Hepatopatias/metabolismo , Amônia/sangue , Cloreto de Amônio/farmacologia , Carbamoil-Fosfato Sintase (Amônia)/metabolismo , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Simulação por Computador , Humanos , Cinética , Fígado/metabolismo , Hepatopatias/sangue , Masculino , Modelos Biológicos , Nitrogênio/metabolismo , Tretinoína/farmacologia , Ureia/metabolismo
12.
Environ Sci Pollut Res Int ; 26(30): 31133-31141, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31463752

RESUMO

To improve crop yielding, a large amount of fungicides is continuously applied during the agricultural management, while the effects of fungicides residues on microbial processing of N in soil need further study. In the present study, two broad spectrum fungicides, chlorothalonil and carbendazim, were applied at the rates of 5, 10, and 50 mg of active ingredient (A.I.) per kg of dry soil combined with urea with 200 mg of N per kg of dry soil under laboratory conditions. The results showed that chlorothalonil obviously retarded the hydrolysis of urea, whereas carbendazim accelerated it in 4 days after the treatments (P < 0.05). Chlorothalonil reduced denitrification, nitrification, and N2O production (P < 0.05), but not for carbendazim. Further analysis on N-associated microbial communities showed chlorothalonil reduced nitrosomonas populations at the rates of 10 and 50 mg of A.I. per kg and autotrophic nitrifying bacterial populations at three application rates (P < 0.05), but Carbendazim decreased nitrosomonas populations only at the rate of 50 mg of A.I. per kg and also autotrophic nitrifying bacterial populations at three rates and heterotrophic nitrifying bacterial populations at the rates of 10 and 50 mg of A.I. per kg. The reasons for this difference were ascribed to arrest urea hydrolysis and impediment of denitrification and nitrification processes by chlorothalonil. In conclusion, to improve crop yielding, chlorothalonil might be more beneficial to conserve soil N by improving soil N fertility, compared with carbendazim.


Assuntos
Benzimidazóis/toxicidade , Carbamatos/toxicidade , Nitrilos/toxicidade , Nitrogênio/metabolismo , Microbiologia do Solo , Ureia/metabolismo , Bactérias/efeitos dos fármacos , Bactérias/metabolismo , Desnitrificação/efeitos dos fármacos , Fertilizantes , Fungicidas Industriais/toxicidade , Hidrólise , Nitrificação/efeitos dos fármacos , Nitrogênio/química , Solo/química , Ureia/química
13.
Int J Food Microbiol ; 308: 108304, 2019 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-31425789

RESUMO

Streptococcus thermophilus strains are used in fermented dairy products for their capacity to metabolize lactose into lactic acid. The rate of lactic acid production in milk is of major economic importance, as rapid acidification prevents growth of undesirable microorganisms. It is also of paramount significance for aroma, texture and flavor of the end product. Besides achieving customer satisfaction, improvement of production rate and operational costs incite industrials into selecting fast acidifying strains. Another important trait of S. thermophilus influencing acidification is the urease, which catabolizes urea into ammonia and has a detrimental effect on acidification. Unfortunately, most of the S. thermophilus strains possess the urease, and the urease-negative ones are necessary for industrial applications. Urease activity is a widely distributed activity in S. thermophilus species, and urease-negative strains are rare. The later are however interesting from an industrial point of view, as they may give faster acidification in dairy applications, because lactic acid is not buffered by urea-derived ammonia. Nowadays, the efforts to improve the characteristics of strains for industrial applications are based on natural strategies such as random mutagenesis. This implies the need of a screening method that is efficient in terms of time and success. In this context, the aim of this study was the development of a new medium that allows selection of urease-defective mutants based on S. thermophilus colony morphology. Discrimination capacity of the new medium was verified using previously characterized urease-negative recombinant strains. The new milk-based medium, applied to industrial S. thermophilus strains subjected to UV mutagenesis, allowed the selection of 3 mutants, partially or completely defective in urease activity. Genetic characterization of urease-defective mutants highlighted the presence of nonsense or missense mutations in the ureA, ureC and ureG genes, thus supporting their phenotype. Evaluation of milk acidification revealed increased performance for one out of three urease-defective mutants compared to wild-type strains.


Assuntos
Amônia/metabolismo , Streptococcus thermophilus/genética , Streptococcus thermophilus/metabolismo , Ureia/metabolismo , Urease/genética , Animais , Ácido Láctico/biossíntese , Lactose/metabolismo , Leite/metabolismo , Fenótipo
14.
Chem Asian J ; 14(17): 2953-2957, 2019 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-31321878

RESUMO

This paper describes the synthesis of protein microtube motors having a urease interior surface and highlights their nonbubble-propelled behavior driven by enzymatic reaction (urea→NH3 and CO2 ). The precursor microtubes were prepared by layer-by-layer assembly using a track-etched microporous polycarbonate membrane. Immobilization of a urease on the internal wall was accomplished using avidin-biotin interaction. The tubules swam smoothly in an aqueous media containing a physiological concentration of urea. Each tubule was rotating laterally while moving forward. It is remarkable that the microtubes were digested completely by proteases, demonstrating perfect biodegradability.


Assuntos
Avidina/química , Biotina/química , Urease/metabolismo , Avidina/metabolismo , Biotina/metabolismo , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Cimento de Policarboxilato/química , Porosidade , Ureia/química , Ureia/metabolismo , Urease/química
15.
J Chromatogr A ; 1605: 360355, 2019 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-31315811

RESUMO

Urea, as an end product of protein metabolism and an abundant polar compound, significantly complicates the metabolomic analysis of urine by GC-MS. We developed a sample preparation method removing urea from urine samples prior the GC-MS analysis. The method based on urease immobilized on magnetic microparticles was compared with the others that are conventionally used (liquid-liquid extraction, free urease protocol), and samples without any treatment. To study the impact of sample preparation approaches on the quality of analytical data, we employed comprehensive metabolomic analysis (using both GC-MS and LC-MS/MS platforms) of standard material based on human urine. Multivariate statistical analysis has shown that immobilized urease treatment provides similar results to a free urease approach. However, significant alterations in the profiles of metabolites were observed in the samples without any treatment and after the extraction. Compared to other approaches that were tested, the immobilization of urease on microparticles reduces both the number of artifacts and the variability of the metabolites (average CV of extraction 19.7%, no treatment 11.4%, free urease 5.0%, and immobilized urease 2.5%). The method that was developed was applied in a GC-MS metabolomic experiment of glutaric aciduria type I, where both known diagnostically important biomarkers and unknowns, as the most discriminating compounds, were found.


Assuntos
Métodos Analíticos de Preparação de Amostras , Enzimas Imobilizadas/urina , Cromatografia Gasosa-Espectrometria de Massas/métodos , Fenômenos Magnéticos , Metabolômica/métodos , Urease/urina , Erros Inatos do Metabolismo dos Aminoácidos/metabolismo , Encefalopatias Metabólicas/metabolismo , Cromatografia Líquida/métodos , Estudos de Viabilidade , Glutaril-CoA Desidrogenase/deficiência , Glutaril-CoA Desidrogenase/metabolismo , Humanos , Metaboloma , Análise de Componente Principal , Reprodutibilidade dos Testes , Espectrometria de Massas em Tandem , Ureia/metabolismo
16.
J Appl Microbiol ; 127(5): 1479-1489, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31301204

RESUMO

AIMS: Development of biomineralization technologies has largely focused on microbially induced carbonate precipitation (MICP) via Sporosarcina pasteurii ureolysis; however, as an obligate aerobe, the general utility of this organism is limited. Here, facultative and anaerobic haloalkaliphiles capable of ureolysis were enriched, identified and then compared to S. pasteurii regarding biomineralization activities. METHODS AND RESULTS: Anaerobic and facultative enrichments for haloalkaliphilic and ureolytic micro-organisms were established from sediment slurries collected at Soap Lake (WA). Optimal pH, temperature and salinity were determined for highly ureolytic enrichments, with dominant populations identified via a combination of high-throughput SSU rRNA gene sequencing, clone libraries and Sanger sequencing of isolates. The enrichment cultures consisted primarily of Sporosarcina- and Clostridium-like organisms. Ureolysis rates and direct cell counts in the enrichment cultures were comparable to the S. pasteurii (strain ATCC 11859) type strain. CONCLUSIONS: Ureolysis rates from both facultatively and anaerobically enriched haloalkaliphiles were either not statistically significantly different to, or statistically significantly higher than, the S. pasteurii (strain ATCC 11859) rates. Work here concludes that extreme environments can harbour highly ureolytic active bacteria with potential advantages for large scale applications, such as environments devoid of oxygen. SIGNIFICANCE AND IMPACT OF THE STUDY: The bacterial consortia and isolates obtained add to the possible suite of organisms available for MICP implementation, therefore potentially improving the economics and efficiency of commercial biomineralization.


Assuntos
Álcalis/metabolismo , Carbonato de Cálcio/metabolismo , Sporosarcina/metabolismo , Ureia/metabolismo , Anaerobiose , Bactérias/metabolismo , Carbonato de Cálcio/química , Sedimentos Geológicos/microbiologia , Consórcios Microbianos , Sporosarcina/genética , Sporosarcina/isolamento & purificação
17.
Toxicol Ind Health ; 35(8): 537-547, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31337283

RESUMO

The adverse health consequences of environmental, occupational, and dietary exposure to either diethylnitrosamine (DEN) or cadmium (Cd) have been widely investigated. However, because most environmental exposures to xenobiotics do not occur in isolation but in mixtures, the effects of simultaneous exposure to both DEN and Cd on hepatorenal function deserves investigation. The present study investigated the impact of 7 days oral co-exposure to 10 mg/kg body weight (b.w.) of DEN and 5 mg/kg b.w. of Cd on biomarkers of hepatic and renal functions, antioxidant defense systems, and oxidative stress indices in the liver and kidney of prepubertal rats. The results showed that the significant (p < 0.05) increases in the levels of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, gamma glutamyl transferase, urea, and creatinine following separate administration of DEN and Cd to rats were further increased in the co-exposure group. Moreover, marked decreases in the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase as well as glutathione levels following individual administration of DEN and Cd to rats were exacerbated in the co-exposure group. Further, the marked increase in the lipid peroxidation level and the histopathological lesions in the liver and kidney of rats treated with DEN or Cd alone were intensified in the co-exposure group These findings indicate that co-exposure to DEN and Cd elicited more severe hepatic and renal oxidative damage in the rats, thus suggesting a greater risk to humans who are co-exposed to them.


Assuntos
Cádmio/toxicidade , Dietilnitrosamina/toxicidade , Rim/efeitos dos fármacos , Fígado/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Alanina Transaminase/metabolismo , Fosfatase Alcalina/metabolismo , Animais , Aspartato Aminotransferases/metabolismo , Catalase/metabolismo , Creatinina/metabolismo , Sinergismo Farmacológico , Glutationa/metabolismo , Masculino , Ratos , Ratos Wistar , Superóxido Dismutase/metabolismo , Ureia/metabolismo , gama-Glutamiltransferase/metabolismo
18.
PLoS One ; 14(7): e0219546, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31329617

RESUMO

Phosphorus (P) deficiency in early lactating dairy cows is receiving increased attention because of incentives aiming at curtailing environmental pollution with P by reducing dietary P in ruminant diets. An in-vitro study using bovine hepatocytes incubated for 7 days with phosphate (Pi) concentrations of 0.9, 1.8 or 2.7 mmol/L, and an in-vivo study feeding late pregnant dairy cows diets with either adequate (0.28% and 0.44% in DM ante-partum and post-partum respectively) or low P content (0.15% and 0.20% in DM ante-partum and post-partum respectively) from 4 weeks before to 4 weeks after calving were conducted to explore effects of P deprivation on liver function. In vitro the relative abundance of mRNA of key enzymes of the carbohydrate metabolism in incubated hepatocytes and liver metabolites in culture medium were determined. In vivo health and productivity of experimental cows on low and adequate dietary P supply were monitored, and liver tissue and blood samples were obtained repeatedly. Liver tissue was assayed for its triacylglycerol-, mineral and water content as well as for the relative abundance of mRNA of enzymes of the carbohydrate-, fat- and protein metabolism. Reduced Pi-availability was not associated with altered enzyme transcription rates or metabolic activity in-vitro. The most prominent clinical finding associated with P deprivation in-vivo was feed intake depression developing after the first week of lactation. Accordingly cows on low P diets had lower milk yield and showed more pronounced increases in liver triacylglycerol after calving. Although the liver P content decreased in P deficient cows, neither negative effects on enzyme transcription rates nor on blood parameters indicative of impaired liver metabolic activity or liver injury were identified. These results indicate the P deprivation only indirectly affects the liver through exacerbation of the negative energy balance occurring as P deficient cows become anorectic.


Assuntos
Indústria de Laticínios , Fígado/metabolismo , Fígado/fisiologia , Fósforo/deficiência , Fósforo/metabolismo , Análise de Variância , Animais , Bovinos , Células Cultivadas , Comportamento Alimentar , Glucose/metabolismo , Hepatócitos/metabolismo , L-Lactato Desidrogenase/metabolismo , Leite , Fosfatos/sangue , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ureia/metabolismo
19.
PLoS One ; 14(6): e0218396, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31211807

RESUMO

Microbially induced calcium carbonate precipitation (MICP) is a potential method for improvement of soil. A laboratory study was conducted to investigate the influence of temperatures for soil improvement by MICP. The ureolytic activity experiments, MICP experiments in aqueous solution and sand column using Sporosarcina pasteurii were conducted at different temperatures(10, 15, 20, 25 and 30°C). The results showed there were microbially induced CaCO3 precipitation at all the temperatures from 10 to 30°C. The results of ureolytic activity experiments showed that the bacterial had higher ureolytic activity at high temperatures within the early 20 hours, however, the ureolytic activity at higher temperatures decreased more quickly than at lower temperatures. The results of MICP experiments in aqueous solution and sand column were consistent with tests of ureolytic activity. Within 20 to 50 hours of the start of the test, more CaCO3 precipitation was precipitated at higher temperature, subsequently, the precipitation rate of all experiments decreased, and the higher the temperature, the faster the precipitation rate dropped. The final precipitation amount of CaCO3 in aqueous solution and sand column tests at 10 °C was 92% and 37% higher than that at 30 °C. The maximum unconfined compressive strength of MICP treated sand column at 10 °C was 135% higher than that at 30 °C. The final treatment effect of MICP at lower temperature was better than that at high temperature within the temperature range studied. The reason for better treatment effect at lower temperatures was due to the longer retention time of ureolytic activity of bacteria at lower temperatures.


Assuntos
Carbonato de Cálcio/química , Microbiologia do Solo , Sporosarcina/metabolismo , Carbonato de Cálcio/metabolismo , Precipitação Química/efeitos dos fármacos , Sporosarcina/química , Temperatura Ambiente , Ureia/química , Ureia/metabolismo , Água/química
20.
Int J Mol Sci ; 20(12)2019 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-31242575

RESUMO

Elucidation of molecular and cellular mechanisms of the uremic syndrome is a very challenging task. More than 130 substances are now considered to be "uremic toxins" and represent a very diverse group of molecules. The toxicity of these molecules affects many cellular processes, and expectably, some of them are able to disrupt mitochondrial functioning. However, mitochondria can be the source of uremic toxins as well, as the mitochondrion can be the site of complete synthesis of the toxin, whereas in some scenarios only some enzymes of the pathway of toxin synthesis are localized here. In this review, we discuss the role of mitochondria as both the target and source of pathological processes and toxic compounds during uremia. Our analysis revealed about 30 toxins closely related to mitochondria. Moreover, since mitochondria are key regulators of cellular redox homeostasis, their functioning might directly affect the production of uremic toxins, especially those that are products of oxidation or peroxidation of cellular components, such as aldehydes, advanced glycation end-products, advanced lipoxidation end-products, and reactive carbonyl species. Additionally, as a number of metabolic products can be degraded in the mitochondria, mitochondrial dysfunction would therefore be expected to cause accumulation of such toxins in the organism. Alternatively, many uremic toxins (both made with the participation of mitochondria, and originated from other sources including exogenous) are damaging to mitochondrial components, especially respiratory complexes. As a result, a positive feedback loop emerges, leading to the amplification of the accumulation of uremic solutes. Therefore, uremia leads to the appearance of mitochondria-damaging compounds, and consecutive mitochondrial damage causes a further rise of uremic toxins, whose synthesis is associated with mitochondria. All this makes mitochondrion an important player in the pathogenesis of uremia and draws attention to the possibility of reducing the pathological consequences of uremia by protecting mitochondria and reducing their role in the production of uremic toxins.


Assuntos
Mitocôndrias/metabolismo , Ureia/metabolismo , Uremia/metabolismo , Lesão Renal Aguda/complicações , Lesão Renal Aguda/metabolismo , Animais , Antioxidantes/farmacologia , Antioxidantes/uso terapêutico , Humanos , Mitocôndrias/efeitos dos fármacos , Terapia de Alvo Molecular , Oxirredução/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Insuficiência Renal Crônica/complicações , Insuficiência Renal Crônica/metabolismo , Toxinas Biológicas/metabolismo , Toxinas Biológicas/toxicidade , Ureia/toxicidade , Uremia/sangue , Uremia/tratamento farmacológico , Uremia/etiologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA