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1.
J Med Microbiol ; 70(8)2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34338626

RESUMO

Introduction. Biofilm formation is a major virulence factor associated with Staphylococcus aureus infections. However, the influence of plasma proteins on biofilm formation of clinical isolates in vitro remains unclear.Hypotheses. We hypothesized that coating surfaces with plasma proteins might induce biofilm formation by S. aureus of different clonal lineages.Aim. To evaluate biofilm production by clinical S. aureus isolates of different clonal lineages isolated in Rio de Janeiro hospitals and investigated the presence of biofilm-associated genes.Methodology. This study assessed biofilm production of 60 S. aureus isolates in polystyrene microtitre plates with and without fibrinogen or fibronectin. The biochemical composition of the biofilm matrices was determined and the biofilm formation on fibrinogen-coated surfaces was also evaluated by confocal laser scanning microscopy. The presence of biofilm-related genes was detected by PCR, and the typing and functionality of agr operon was also evaluated.Results. Most of the isolates (45 %) were weak biofilm producers or non-producers. However, most of them presented a significant increase in biofilm production on plates covered with plasma proteins. There was no significant difference in biofilm formation between methicillin-resistant and -susceptible S. aureus isolates, or between different clonal lineages, except for ST30-IV (weak producers) and ST239-III (strong producers). The fnbB gene was associated with higher biofilm production.Conclusion. An increase in biofilm production in the presence of plasma proteins highlights the importance of investigating biofilm formation by S. aureus clinical isolates under different conditions since this virulence factor contributes to persistent infections and increased resistance to antimicrobials.


Assuntos
Biofilmes/crescimento & desenvolvimento , Fibrinogênio , Fibronectinas , Staphylococcus aureus Resistente à Meticilina/patogenicidade , Staphylococcus aureus/patogenicidade , Adesinas Bacterianas/genética , Aderência Bacteriana/genética , Proteínas de Bactérias/genética , Genes Bacterianos , Genótipo , Humanos , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Staphylococcus aureus Resistente à Meticilina/fisiologia , Óperon , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/genética , Staphylococcus aureus/isolamento & purificação , Staphylococcus aureus/fisiologia , Transativadores/genética
2.
Stroke ; 52(4): 1322-1329, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33719516

RESUMO

BACKGROUND AND PURPOSE: Delirium is an acute and fluctuating impairment of attention, cognition, and behavior. Although common in stroke, studies that associate the clinical subtypes of delirium with functional outcome and death are lacking. We aimed to evaluate the influence of delirium occurrence and its different motor subtypes over stroke patients' prognosis. METHODS: Prospective cohort of stroke patients with symptom onset within 72 hours before research admission. Delirium was diagnosed by Confusion Assessment Method for the Intensive Care Unit, and its motor subtypes were defined according to the Richmond Agitation-Sedation Scale. The main outcome was functional dependence or death (modified Rankin Scale>2) at 90 days comparing: delirium versus no delirium patients; and between motor subtypes. Secondary outcomes included modified Rankin Scale score >2 at 30 days and 90-day-mortality. RESULTS: Two hundred twenty-seven patients were enrolled. Delirium occurred in 71 patients (31.3%), with the hypoactive subtype as the most frequent, in 41 subjects (57.8%). Delirium was associated with increased risk of death and functional dependence at 30 and 90 days and higher 90-day mortality. Multivariate analysis showed delirium (odds ratio, 3.28 [95% CI, 1.17-9.22]) as independent predictor of modified Rankin Scale >2 at 90 days. CONCLUSIONS: Delirium is frequent in stroke patients in the acute phase. Its occurrence-specifically in mixed and hypoactive subtypes-seems to predict worse outcomes in this population. To our knowledge, this is the first study to prospectively investigate differences between delirium motor subtypes over functional outcome three months poststroke. Larger studies are needed to elucidate the relationship between motor subtypes of delirium and functional outcomes in the context of acute stroke.

3.
Biotechnol Prog ; 37(3): e3131, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33511791

RESUMO

The objective of this study was to compare the potential of mono-rhamnolipids (mono-RML) and di-rhamnolipids (di-RML) against biofilm formation on carbon steel coupons submitted to oil produced water for 14 days. The antibiofilm effect of the RML on the coupons was analyzed by scanning electron microscopy (SEM) and by epifluorescence microscopy, and the contact angle was measured using a goniometer. SEM analysis results showed that all RML congeners had effective antibiofilm action, as well as preliminary anticorrosion evaluation confirmed that all RML congeners prevented the metal deterioration. In more detail, epifluorescence microscopy showed that mono-RML were the most efficient congeners in preventing microorganism's adherence on the carbon steel metal. Image analyses indicate the presence of 15.9%, 3.4%, and <0.1% of viable particles in di-RML, mono/di-RML and mono-RML pretreatments, respectively, in comparison to control samples. Contact angle results showed that the crude carbon steel coupon presented hydrophobic character favoring hydrophobic molecules adhesion. We calculated the theoretical polarity of the RML congeners and verified that mono-RML (log P = 3.63) presented the most hydrophobic character. This had perfect correspondence to contact angle results, since mono-RML conditioning (58.2°) more significantly changed the contact angle compared with the conditioning with one of the most common surfactants used on oil industry (29.4°). Based on the results, it was concluded that rhamnolipids are efficient molecules to be used to avoid biofilm on carbon steel metal when submitted to oil produced water and that a higher proportion of mono-rhamnolipids is more indicated for this application.

4.
Front Microbiol ; 11: 588263, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33193246

RESUMO

Penicillium echinulatum 2HH and Penicillium oxalicum 114-2 are well-known cellulase fungal producers. However, few studies addressing global mechanisms for gene regulation of these two important organisms are available so far. A recent finding that the 2HH wild-type is closely related to P. oxalicum leads to a combined study of these two species. Firstly, we provide a global gene regulatory network for P. echinulatum 2HH and P. oxalicum 114-2, based on TF-TG orthology relationships, considering three related species with well-known regulatory interactions combined with TFBSs prediction. The network was then analyzed in terms of topology, identifying TFs as hubs, and modules. Based on this approach, we explore numerous identified modules, such as the expression of cellulolytic and xylanolytic systems, where XlnR plays a key role in positive regulation of the xylanolytic system. It also regulates positively the cellulolytic system by acting indirectly through the cellodextrin induction system. This remarkable finding suggests that the XlnR-dependent cellulolytic and xylanolytic regulatory systems are probably conserved in both P. echinulatum and P. oxalicum. Finally, we explore the functional congruency on the genes clustered in terms of communities, where the genes related to cellular nitrogen, compound metabolic process and macromolecule metabolic process were the most abundant. Therefore, our approach allows us to confer a degree of accuracy regarding the existence of each inferred interaction.

5.
Sci Rep ; 10(1): 6706, 2020 04 21.
Artigo em Inglês | MEDLINE | ID: mdl-32317676

RESUMO

Magnetosomes are intracellular magnetic nanocrystals composed of magnetite (Fe3O4) or greigite (Fe3S4), enveloped by a lipid bilayer membrane, produced by magnetotactic bacteria. Because of the stability of these structures in certain environments after cell death and lysis, magnetosome magnetite crystals contribute to the magnetization of sediments as well as providing a fossil record of ancient microbial ecosystems. The persistence or changes of the chemical and magnetic features of magnetosomes under certain conditions in different environments are important factors in biotechnology and paleomagnetism. Here we evaluated the thermal stability of magnetosomes in a temperature range between 150 and 500 °C subjected to oxidizing conditions by using in situ scanning transmission electron microscopy. Results showed that magnetosomes are stable and structurally and chemically unaffected at temperatures up to 300 °C. Interestingly, the membrane of magnetosomes was still observable after heating the samples to 300 °C. When heated between 300 °C and 500 °C cavity formation in the crystals was observed most probably associated to the partial transformation of magnetite into maghemite due to the Kirkendall effect at the nanoscale. This study provides some insight into the stability of magnetosomes in specific environments over geological periods and offers novel tools to investigate biogenic nanomaterials.

6.
Environ Microbiol Rep ; 12(3): 288-295, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32100462

RESUMO

Transmission electron microscopy (TEM) and rock magnetic study of ferromanganese nodule sample JC120-104B collected from Clarion-Clipperton zone (CCZ) in the eastern Pacific Ocean indicate the presence of biogenic magnetite (magnetofossils). First-order reversal curves (FORCs) and decomposition of isothermal remanent magnetization (IRM) curves were used as the main tool for the characterization of magnetic properties of the bulk magnetic minerals present in the sample. TEM was performed for the direct identification of biogenic magnetic minerals (magnetofossils). The nodule sample has distinctive alternating Mn and Fe-rich layers per micro-X-ray fluorescence data. While diagenetic precipitation of Mn is known for the less oxygenated environment, the presence of biogenic magnetite is also common in the environments where the supply of oxygen is limited. Moreover, the increase in magnetic properties is consistent with the increase in Mn-content, which is related to favourable conditions for Mn precipitation as well as magnetite biomineralization in oxic-suboxic transition zone. Investigations on magnetofossil fingerprints lead to a better understanding of paleoenvironmental conditions involved in the formation and growth of deep-sea ferromanganese nodules.


Assuntos
Biomineralização , Sedimentos Geológicos/microbiologia , Ferro , Manganês , Óxido Ferroso-Férrico , Microscopia Eletrônica de Transmissão , Oceanos e Mares
7.
Microbiol Resour Announc ; 9(1)2020 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-31896630

RESUMO

We report the complete 4.1-Mb genome sequence of strain BW-2, a magnetotactic, sulfur-oxidizing rod, belonging to the family Ectothiorhodospiraceae of the class Gammaproteobacteria, that biomineralizes membrane-bounded magnetite nanocrystals in its magnetosomes. This genome sequence, in comparison with those of other magnetotactic bacteria, is essential for understanding the origin and evolution of magnetotaxis and magnetosome biomineralization.

8.
Environ Microbiol ; 22(4): 1495-1506, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31188524

RESUMO

The most well-recognized magnetoreception behaviour is that of the magnetotactic bacteria (MTB), which synthesize membrane-bounded magnetic nanocrystals called magnetosomes via a biologically controlled process. The magnetic minerals identified in prokaryotic magnetosomes are magnetite (Fe3 O4 ) and greigite (Fe3 S4 ). Magnetosome crystals, regardless of composition, have consistent, species-specific morphologies and single-domain size range. Because of these features, magnetosome magnetite crystals possess specific properties in comparison to abiotic, chemically synthesized magnetite. Despite numerous discoveries regarding MTB phylogeny over the last decades, this diversity is still considered underestimated. Characterization of magnetotactic microorganisms is important as it might provide insights into the origin and establishment of magnetoreception in general, including eukaryotes. Here, we describe the magnetotactic behaviour and characterize the magnetosomes from a flagellated protist using culture-independent methods. Results strongly suggest that, unlike previously described magnetotactic protists, this flagellate is capable of biomineralizing its own anisotropic magnetite magnetosomes, which are aligned in complex aggregations of multiple chains within the cell. This organism has a similar response to magnetic field inversions as MTB. Therefore, this eukaryotic species might represent an early origin of magnetoreception based on magnetite biomineralization. It should add to the definition of parameters and criteria to classify biogenic magnetite in the fossil record.


Assuntos
Óxido Ferroso-Férrico/metabolismo , Magnetossomos/metabolismo , Evolução Biológica , Biomineralização , Eucariotos , Flagelos , Fenômenos Magnéticos
9.
Antonie Van Leeuwenhoek ; 113(2): 197-209, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31535336

RESUMO

Magnetotactic bacteria have intracellular chains of magnetic nanoparticles, conferring to their cellular body a magnetic moment that permits the alignment of their swimming trajectories to the geomagnetic field lines. That property is known as magnetotaxis and makes them suitable for the study of bacterial motion. The present paper studies the swimming trajectories of uncultured magnetotactic cocci and of the multicellular magnetotactic prokaryote 'Candidatus Magnetoglobus multicellularis' exposed to magnetic fields lower than 80 µT. It was assumed that the trajectories are cylindrical helixes and the axial velocity, the helix radius, the frequency and the orientation of the trajectories relative to the applied magnetic field were determined from the experimental trajectories. The results show the paramagnetic model applies well to magnetotactic cocci but not to 'Ca. M. multicellularis' in the low magnetic field regime analyzed. Magnetotactic cocci orient their trajectories as predicted by classical magnetotaxis but in general 'Ca. M. multicellularis' does not swim following the magnetic field direction, meaning that for it the inversion in the magnetic field direction represents a stimulus but the selection of the swimming direction depends on other cues or even on other mechanisms for magnetic field detection.


Assuntos
Deltaproteobacteria/fisiologia , Campos Magnéticos , Células Procarióticas/fisiologia , Deltaproteobacteria/ultraestrutura , Microscopia de Vídeo , Células Procarióticas/ultraestrutura
10.
Eur Biophys J ; 48(6): 513-521, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31203416

RESUMO

Magnetotactic bacteria are microorganisms that present intracellular chains of magnetic nanoparticles, the magnetosome chain. A challenge in the study of magnetotactic bacteria is the measurement of the magnetic moment associated with the magnetosome chain. Several techniques have been used to estimate the average magnetic moment of a population of magnetotactic bacteria, and others permit the measurement of the magnetic moment of individual bacteria. The U-turn technique allows the measurement of the individual magnetic moment and other parameters associated with the movement and magnetotaxis, such as the velocity and the orientation angle of the trajectory relative to the applied magnetic field. The aim of the present paper is to use the U-turn technique in a population of uncultured magnetotactic cocci to measure the magnetic moment, the volume, orientation angle and velocity for the same individuals. Our results showed that the magnetic moment is distributed in a log-normal distribution, with a mean value of 8.2 × 10-15 Am2 and median of 5.4 × 10-15 Am2. An estimate of the average magnetic moment using the average value of the orientation cosine produces a value similar to the median of the distribution and to the average magnetic moment obtained using transmission electron microscopy. A strong positive correlation is observed between the magnetic moment and the volume. There is no correlation between the magnetic moment and the orientation cosine and between the magnetic moment and the velocity. Those null correlations can be explained by our current understanding of magnetotaxis.


Assuntos
Bactérias , Fenômenos Magnéticos , Movimento
11.
PLoS One ; 14(4): e0215657, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31013301

RESUMO

Magnetotactic bacteria biomineralize intracellular magnetic nanocrystals surrounded by a lipid bilayer called magnetosomes. Due to their unique characteristics, magnetite magnetosomes are promising tools in Biomedicine. However, the uptake, persistence, and accumulation of magnetosomes within mammalian cells have not been well studied. Here, the endocytic pathway of magnetite magnetosomes and their effects on human cervix epithelial (HeLa) cells were studied by electron microscopy and high spatial resolution nano-analysis techniques. Transmission electron microscopy of HeLa cells after incubation with purified magnetosomes showed the presence of magnetic nanoparticles inside or outside endosomes within the cell, which suggests different modes of internalization, and that these structures persisted beyond 120 h after internalization. High-resolution transmission electron microscopy and electron energy loss spectra of internalized magnetosome crystals showed no structural or chemical changes in these structures. Although crystal morphology was preserved, iron oxide crystalline particles of approximately 5 nm near internalized magnetosomes suggests that minor degradation of the original mineral structures might occur. Cytotoxicity and microscopy analysis showed that magnetosomes did not result in any apparent effect on HeLa cells viability or morphology. Based on our results, magnetosomes have significant biocompatibility with mammalian cells and thus have great potential in medical, biotechnological applications.


Assuntos
Endocitose , Óxido Ferroso-Férrico/metabolismo , Magnetossomos/metabolismo , Biotecnologia/métodos , Sobrevivência Celular , Endossomos/metabolismo , Endossomos/ultraestrutura , Células HeLa , Humanos , Teste de Materiais , Microscopia Eletrônica de Transmissão , Testes de Toxicidade
12.
Biomark Insights ; 14: 1177271919826550, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30728712

RESUMO

Introduction and Objective: The main goal of asthma treatment is to achieve and maintain clinical control of the disease. The exhaled fraction nitric oxide (FeNO) level is a biomarker of T-helper cell type 2 (Th2) inflammation of the airways. Our objective was to determine whether the FeNO level can be used to discriminate between patients with controlled, partially controlled, and uncontrolled asthma. Materials and Methods: The FeNO level and asthma control were evaluated in a retrospective and analytic cross-sectional study through data collected from asthmatic patients who were assessed by clinical history, asthma control, physical examination, spirometry, and FeNO level. Asthma control was determined by the criteria of the Global Initiative for Asthma and classified as controlled asthma, partially controlled asthma, and uncontrolled asthma. The FeNO values were classified as low (<25 ppb) or intermediate/high (⩾25 ppb) based on the American Thoracic Society recommendations. Results: The symptoms of 81 asthmatic patients were classified as controlled (34 [42%] patients), partially controlled (27 [33.3%] patients), and uncontrolled (20 [24.7%] patients). The FeNO level discriminated between the uncontrolled and controlled groups (P = .01) and between the uncontrolled and partially controlled groups (P = .01), but not between the controlled and partially controlled groups (P = .98). An FeNO level >30 ppb was associated with uncontrolled asthma (P = .0001) with an area under the receiver operating characteristic curve of 0.78 (95% confidence interval = 0.65-0.89). Conclusions: FeNO level could be helpful in determining asthma control as >30 ppb was associated with uncontrolled asthma.

13.
Sao Paulo Med J ; 136(5): 398-406, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30570091

RESUMO

BACKGROUND: Secondary prevention of stroke is a very important goal for achieving continuous reduction in stroke mortality rates over the next decades. DESIGN AND SETTING: Cross-sectional analysis on the Brazilian Longitudinal Study of Adult Health -(ELSA-Brasil), with data from Salvador, Vitória, Belo Horizonte, Rio de Janeiro, São Paulo and Porto Alegre. METHODS: This descriptive analysis focused on secondary prevention of stroke among participants who self-reported a medical diagnosis of stroke at the baseline of ELSA-Brasil, and its association with sociodemographic characteristics. RESULTS: Overall, 197 participants (1.3%) reported a prior medical history of stroke. Participants with stroke were older and less educated and had lower mean monthly family income, compared with non-stroke participants. Among all stroke cases, 23.7% did not use any medication for secondary prevention of stroke. Use of secondary prevention was higher among men than among women (respectively, 59.6% versus 40.4%; P = 0.02 for aspirin; and 71.4% versus 28.6%; P = 0.04 for other antiplatelet drugs). Having private health insurance was associated with greater use of less cost-effective and more expensive medications (like angiotensinogen receptor blockers) and a tendency to use antiplatelet drugs other than aspirin, among participants reporting stroke, compared with others. Use of medication decreased as time passed after suffering a stroke. CONCLUSIONS: In this sample of individuals with better access to healthcare services, use of secondary prevention for stroke was low, which may suggest that the situation in the general population is worse. Sex was the most important sociodemographic variable associated with low use of secondary prevention.


Assuntos
Prevenção Secundária/estatística & dados numéricos , Acidente Vascular Cerebral/epidemiologia , Acidente Vascular Cerebral/prevenção & controle , Adulto , Idoso , Análise de Variância , Anticoagulantes/uso terapêutico , Anti-Hipertensivos/uso terapêutico , Brasil/epidemiologia , Estudos Transversais , Feminino , Humanos , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Inibidores da Agregação Plaquetária/uso terapêutico , Fatores de Risco , Autorrelato , Distribuição por Sexo , Fatores Socioeconômicos , Estatísticas não Paramétricas , Acidente Vascular Cerebral/tratamento farmacológico
14.
Säo Paulo med. j ; 136(5): 398-406, Sept.-Oct. 2018. tab
Artigo em Inglês | LILACS | ID: biblio-979375

RESUMO

ABSTRACT BACKGROUND: Secondary prevention of stroke is a very important goal for achieving continuous reduction in stroke mortality rates over the next decades. DESIGN AND SETTING: Cross-sectional analysis on the Brazilian Longitudinal Study of Adult Health ­(ELSA-Brasil), with data from Salvador, Vitória, Belo Horizonte, Rio de Janeiro, São Paulo and Porto Alegre. METHODS: This descriptive analysis focused on secondary prevention of stroke among participants who self-reported a medical diagnosis of stroke at the baseline of ELSA-Brasil, and its association with sociodemographic characteristics. RESULTS: Overall, 197 participants (1.3%) reported a prior medical history of stroke. Participants with stroke were older and less educated and had lower mean monthly family income, compared with non-stroke participants. Among all stroke cases, 23.7% did not use any medication for secondary prevention of stroke. Use of secondary prevention was higher among men than among women (respectively, 59.6% versus 40.4%; P = 0.02 for aspirin; and 71.4% versus 28.6%; P = 0.04 for other antiplatelet drugs). Having private health insurance was associated with greater use of less cost-effective and more expensive medications (like angiotensinogen receptor blockers) and a tendency to use antiplatelet drugs other than aspirin, among participants reporting stroke, compared with others. Use of medication decreased as time passed after suffering a stroke. CONCLUSIONS: In this sample of individuals with better access to healthcare services, use of secondary prevention for stroke was low, which may suggest that the situation in the general population is worse. Sex was the most important sociodemographic variable associated with low use of secondary prevention.


Assuntos
Humanos , Masculino , Feminino , Adulto , Pessoa de Meia-Idade , Idoso , Acidente Vascular Cerebral/prevenção & controle , Acidente Vascular Cerebral/epidemiologia , Prevenção Secundária/estatística & dados numéricos , Fatores Socioeconômicos , Brasil/epidemiologia , Inibidores da Agregação Plaquetária/uso terapêutico , Estudos Transversais , Fatores de Risco , Análise de Variância , Estudos Longitudinais , Distribuição por Sexo , Estatísticas não Paramétricas , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Acidente Vascular Cerebral/tratamento farmacológico , Autorrelato , Anticoagulantes/uso terapêutico , Anti-Hipertensivos/uso terapêutico
15.
Molecules ; 23(10)2018 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-30249983

RESUMO

Magnetotactic bacteria (MTB) biomineralize magnetosomes, which are defined as intracellular nanocrystals of the magnetic minerals magnetite (Fe3O4) or greigite (Fe3S4) enveloped by a phospholipid bilayer membrane. The synthesis of magnetosomes is controlled by a specific set of genes that encode proteins, some of which are exclusively found in the magnetosome membrane in the cell. Over the past several decades, interest in nanoscale technology (nanotechnology) and biotechnology has increased significantly due to the development and establishment of new commercial, medical and scientific processes and applications that utilize nanomaterials, some of which are biologically derived. One excellent example of a biological nanomaterial that is showing great promise for use in a large number of commercial and medical applications are bacterial magnetite magnetosomes. Unlike chemically-synthesized magnetite nanoparticles, magnetosome magnetite crystals are stable single-magnetic domains and are thus permanently magnetic at ambient temperature, are of high chemical purity, and display a narrow size range and consistent crystal morphology. These physical/chemical features are important in their use in biotechnological and other applications. Applications utilizing magnetite-producing MTB, magnetite magnetosomes and/or magnetosome magnetite crystals include and/or involve bioremediation, cell separation, DNA/antigen recovery or detection, drug delivery, enzyme immobilization, magnetic hyperthermia and contrast enhancement of magnetic resonance imaging. Metric analysis using Scopus and Web of Science databases from 2003 to 2018 showed that applied research involving magnetite from MTB in some form has been focused mainly in biomedical applications, particularly in magnetic hyperthermia and drug delivery.


Assuntos
Bactérias/metabolismo , Magnetossomos/química , Nanopartículas/química , Bactérias/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Biotecnologia , Óxido Ferroso-Férrico/química , Óxido Ferroso-Férrico/metabolismo , Ferro/química , Magnetossomos/metabolismo , Sulfetos/química
16.
Antonie Van Leeuwenhoek ; 111(11): 2213-2223, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29915893

RESUMO

Magnetotactic bacteria, for the most part, are free-living, motile, unicellular prokaryotes that inhabit almost all marine and freshwater environments. One notable exception to the unicellular mode, however, are the magnetotactic multicellular prokaryotes. These morphologically unique prokaryotes (e.g., Candidatus Magnetoglobus multicellularis) are motile aggregates of 20-40 genetically identical, Gram-negative cells organised as a sphere (or ovoid in shape) and only motile as a unit. No specific close physical association between magnetotactic bacteria and non-magnetotactic microorganisms has ever been reported. Here, using culture-independent approaches, we show an unusual association between the spherical magnetotactic multicellular prokaryote Ca. Magnetoglobus multicellularis and Pseudoalteromonas species in environmental sediment and water samples collected from the Araruama Lagoon in Brazil. Cells of Pseudoalteromonas species were observed to be physically attached to the surface and, notably, even in the intercellular space of these spherical magnetotactic multicellular prokaryotes. An attempt to correlate the frequency of association between Pseudoalteromonas and magnetotactic multicellular prokaryotes with sediment depth was made but only a slight decrease in the number of Pseudoalteromonas cells per magnetotactic multicellular prokaryote was observed with increasing depth. Similar observations were made with magnetotactic multicellular prokaryotes from another Brazilian Lagoon (Rodrigo de Freitas) and the putative symbiont/parasite was detected. Although our results suggest some sort of specificity in the relationship between these prokaryotes, the precise nature of this association remains unclear.


Assuntos
Deltaproteobacteria/fisiologia , Água Doce/microbiologia , Pseudoalteromonas/fisiologia , Brasil , Deltaproteobacteria/química , Deltaproteobacteria/isolamento & purificação , Magnetismo , Pseudoalteromonas/química , Pseudoalteromonas/isolamento & purificação
17.
Environ Microbiol ; 20(7): 2615-2624, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29806735

RESUMO

Magnetotactic bacteria (MTB) comprise a group of motile microorganisms common in most mesothermal aquatic habitats with pH values around neutrality. However, during the last two decades, a number of MTB from extreme environments have been characterized including: cultured alkaliphilic strains belonging to the Deltaproteobacteria class of the Proteobacteria phylum; uncultured moderately thermophilic strains belonging to the Nitrospirae phylum; cultured and uncultured moderately halophilic or strongly halotolerant bacteria affiliated with the Deltaproteobacteria and Gammaproteobacteria classes and an uncultured psychrophilic species belonging to the Alphaproteobacteria class. Here, we used culture-independent techniques to characterize MTB from an acidic freshwater lagoon in Brazil (pH ∼ 4.4). MTB morphotypes found in this acidic lagoon included cocci, rods, spirilla and vibrioid cells. Magnetite (Fe3 O4 ) was the only mineral identified in magnetosomes of these MTB while magnetite magnetosome crystal morphologies within the different MTB cells included cuboctahedral (present in spirilla), elongated prismatic (present in cocci and vibrios) and bullet-shaped (present in rod-shaped cells). Intracellular pH measurements using fluorescent dyes showed that the cytoplasmic pH was close to neutral in most MTB cells and acidic in some intracellular granules. Based on 16S rRNA gene phylogenetic analyses, some of the retrieved gene sequences belonged to the genus Herbaspirillum within the Betaproteobacteria class of the Proteobacteria phylum. Fluorescent in situ hybridization using a Herbaspirillum-specific probe hybridized with vibrioid MTB in magnetically-enriched samples. Transmission electron microscopy of the Herbaspirillum-like MTB revealed the presence of many intracellular granules and a single chain of elongated prismatic magnetite magnetosomes. Diverse populations of MTB have not seemed to have been described in detail in an acid environment. In addition, this is the first report of an MTB phylogenetically affiliated with Betaproteobacteria class.


Assuntos
Betaproteobacteria/isolamento & purificação , Água Doce/microbiologia , Betaproteobacteria/classificação , Betaproteobacteria/genética , Betaproteobacteria/ultraestrutura , Brasil , Óxido Ferroso-Férrico/análise , Hibridização in Situ Fluorescente , Magnetossomos , Filogenia , RNA Bacteriano , RNA Ribossômico 16S
18.
Bioelectromagnetics ; 39(6): 485-490, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29797587

RESUMO

Bacteria are the simplest model of living organisms and thus are a convenient object for magnetobiological research. This paper describes some effects of combined magnetic fields (CMFs) on the bacterium Rhodospirillum rubrum strain VKM B-1621, which is not a pathogen but was selected due to its wide spectrum of growth abilities. The authors chose magnetic field-resonant phosphorus and iron (Fe3+ ) because P-containing biochemical compounds (standard abbreviations PP1 , AMP, ADP, ATP) provide energy flows in bacteria while iron could take part in formation of magnetosensitive intracellular inclusions. CMFs were produced by interaction of a geomagnetic field (ВDС ) and an alternating electromagnetic field (ВАС ), which were similar in their intensities. Their magnetic characteristics were as follows: (CMF-1) ВDC = 46.80 µÐ¢, ВАС = 86.11 µT, f = 807.0 Hz; (CMF-2) ВDC = 46.80 µÐ¢, ВАС = 86.11 µT, f = 38.3 Hz; that is, the frequencies of applied alternating electromagnetic fields coincided with cyclotron frequencies of phosphorus or ferric ions, respectively. The blank variants were exposed to the geomagnetic field. The CMFs increased bacterial consumption of dissolved iron as measured by residual concentrations of iron in the medium (P > 99%). An increase of bacterial nitrate reduction in the CMFs was statistically insignificant (P > 90%) when measured by residual concentrations of nitrate. Application of CMFs can influence bacterial activity and metabolism. Bioelectromagnetics. 2018;39:485-490, 2018. © 2018 Wiley Periodicals, Inc.


Assuntos
Campos Magnéticos , Rhodospirillum rubrum/metabolismo , Análise de Variância , Ferro/metabolismo , Microscopia Eletrônica de Transmissão , Nitratos/metabolismo , Rhodospirillum rubrum/ultraestrutura
19.
Protoplasma ; 255(6): 1751-1761, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29846801

RESUMO

This work aimed to evaluate the drought tolerance of transformed plants of the cultivar BRSMG Curinga that overexpress the rice phospholipase D α1 (OsPLDα1) gene. The productivity of independent transformation event plants of the OsPLDα1 gene was evaluated in an experiment where 19 days of water deficit were applied at the reproductive stage, a very strict growing condition for upland rice. The non-genetically modified cultivar (NGM) under drought treatment reduced productivity by 89% compared with that under irrigated treatment, whereas transformed plants (PLDα1_E2) reduced productivity by only 41%. After the drought treatment, the PLDα1_E2 plants productivity was five times greater than that of the NGM plant. Moreover, no adverse effects on growth and development of the transgenic plants were observed. Seven days after the resumption of irrigation, PLDα1_E2 plants had higher stomatal conductance, greater photosynthetic rate, and transpiration rate than did NGM plants, as well as a higher expression level of the OsPLDα1 gene. A delay in the senescence process was observed in these PLDα1_E2 plants, and this was determined for the recovery of photosynthesis, with greater expression of the Rubisco and lower expression of the SOD. This finding was suggestive of decreased oxidative stress, probably due to gas exchange by the partial closure of the stomata of these transformed plants, which prevented the formation of reactive oxygen species. OsPLDα1 gene overexpression resulted in a reduction in production loss under severe water deficit and revealed a possibility for the development of upland rice cultivars that are more tolerant to extreme drought conditions.


Assuntos
Adaptação Fisiológica , Secas , Oryza/enzimologia , Oryza/fisiologia , Fosfolipases/metabolismo , Proteínas de Plantas/metabolismo , Regulação da Expressão Gênica de Plantas , Oryza/genética , Fotossíntese , Estômatos de Plantas/fisiologia , Transpiração Vegetal/fisiologia , Plantas Geneticamente Modificadas , Superóxido Dismutase/metabolismo
20.
Gen Dent ; 65(5): 72-76, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28862593

RESUMO

Hypohidrotic ectodermal dysplasia (HED) is a rare ectodermal disease with a systemic expression. Oral abnormalities are common and may include hypodontia and shape irregularities in the primary and permanent dentitions. Rehabilitation of the dental arches in pediatric patients with HED is a challenge because HED is a multifactorial disease that demands a complicated treatment approach and most dentists have limited experience or training in the necessary treatment. In addition, pediatric patients often lack the patience or ability to cooperate with complex prosthetic treatment. This case report describes a simplified technique used to fabricate complete dentures for a 4-year-old HED patient in 4 sessions.


Assuntos
Prótese Total , Displasia Ectodérmica Anidrótica Tipo 1/complicações , Reabilitação Bucal/métodos , Pré-Escolar , Humanos , Masculino
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