RESUMO
Mutations in PINK1 and parkin highlight the mitochondrial axis of Parkinson's disease (PD) pathogenesis. PINK1/parkin regulation of the transcriptional repressor PARIS bears direct relevance to dopamine neuron survival through augmentation of PGC-1α-dependent mitochondrial biogenesis. Notably, knockout of PARIS attenuates dopaminergic neurodegeneration in mouse models, indicating that interventions that prevent dopaminergic accumulation of PARIS could have therapeutic potential in PD. To this end, we have identified the deubiquitinase cylindromatosis (CYLD) to be a regulator of PARIS protein stability and proteasomal degradation via the PINK1/parkin pathway. Knockdown of CYLD in multiple models of PINK1 or parkin inactivation attenuates PARIS accumulation by modulating its ubiquitination levels and relieving its repressive effect on PGC-1α to promote mitochondrial biogenesis. Together, our studies identify CYLD as a negative regulator of dopamine neuron survival, and inhibition of CYLD may potentially be beneficial in PD by lowering PARIS levels and promoting mitochondrial biogenesis.
Assuntos
Neurônios Dopaminérgicos , Doença de Parkinson , Animais , Enzima Desubiquitinante CYLD/genética , Enzima Desubiquitinante CYLD/metabolismo , Enzimas Desubiquitinantes/metabolismo , Dopamina/metabolismo , Neurônios Dopaminérgicos/metabolismo , Camundongos , Doença de Parkinson/genética , Doença de Parkinson/metabolismo , UbiquitinaçãoRESUMO
Nitrification, the microbial oxidation of ammonia (NH3) to nitrite (NO2-) and NO2- to nitrate (NO3-), plays a vital role in ocean nitrogen cycling. Characterizing the distribution of nitrifying organisms over environmental gradients can help predict how nitrogen availability may change with shifting ocean conditions, for example, due to loss of dissolved oxygen (O2). We characterized the distribution of nitrifiers at 5 depths spanning the oxic to hypoxic zone of the offshore Benguela upwelling system above the continental slope off Namibia. Based on 16S rRNA gene amplicon sequencing, the proportional abundance of nitrifiers (ammonia and nitrite oxidizers) increased with depth, driven by an increase in ammonia-oxidizing archaea (AOA; Thaumarchaeota) to up to 33% of the community at hypoxic depths where O2 concentrations fell to ~25 µM. The AOA community transitioned from being dominated by a few members at oxic depths to a more even representation of taxa in the hypoxic zone. In comparison, the community of NO2--oxidizing bacteria (NOB), composed primarily of Nitrospinae, was far less abundant and exhibited higher evenness at all depths. The AOA:NOB ratio declined with depth from 41:1 in the oxic zone to 27:1 under hypoxia, suggesting potential variation in the balance between NO2- production and consumption via nitrification. Indeed, in contrast to prior observations from more O2-depleted sites closer to shore, NO2- did not accumulate at hypoxic depths near this offshore site, potentially due in part to a tightened coupling between AOA and NOB.
Assuntos
Amônia/metabolismo , Bactérias/classificação , Bactérias/metabolismo , Hipóxia , Nitritos/metabolismo , Nitrogênio/metabolismo , Amônia/química , Bactérias/genética , Namíbia , Nitritos/química , Oxirredução , Filogenia , RNA Ribossômico 16S/genéticaRESUMO
The increased availability and utilization of acute mechanical circulatory support use in cardiogenic shock has led to an increased need for multidisciplinary communication with specialized shock centers. The wide variability of hemodynamic data and local expertise raises a unique communication problem in capturing and documenting necessary information to guide decision making.
RESUMO
BACKGROUND: In ST-segment-elevation myocardial infarction (STEMI), infarct size correlates directly with heart failure and mortality. Preclinical testing has shown that, in comparison with reperfusion alone, mechanically unloading the left ventricle (LV) before reperfusion reduces infarct size and that 30 minutes of unloading activates a cardioprotective program that limits reperfusion injury. The DTU-STEMI pilot trial (Door-To-Unload in STEMI Pilot Trial) represents the first exploratory study testing whether LV unloading and delayed reperfusion in patients with STEMI without cardiogenic shock is safe and feasible. METHODS: In a multicenter, prospective, randomized exploratory safety and feasibility trial, we assigned 50 patients with anterior STEMI to LV unloading by using the Impella CP followed by immediate reperfusion (U-IR) versus delayed reperfusion after 30 minutes of unloading (U-DR). The primary safety outcome was a composite of major adverse cardiovascular and cerebrovascular events at 30 days. Efficacy parameters included the assessment of infarct size by using cardiac magnetic resonance imaging. RESULTS: All patients completed the U-IR (n=25) or U-DR (n=25) protocols with respective mean door-to-balloon times of 72 versus 97 minutes. Major adverse cardiovascular and cerebrovascular event rates were not statistically different between the U-IR versus U-DR groups (8% versus 12%, respectively, P=0.99). In comparison with the U-IR group, delaying reperfusion in the U-DR group did not affect 30-day mean infarct size measured as a percentage of LV mass (15±12% versus 13±11%, U-IR versus U-DR, P=0.53). CONCLUSIONS: We report that LV unloading using the Impella CP device with a 30-minute delay before reperfusion is feasible within a relatively short time period in anterior STEMI. The DTU-STEMI pilot trial did not identify prohibitive safety signals that would preclude proceeding to a larger pivotal study of LV unloading before reperfusion. An appropriately powered pivotal trial comparing LV unloading before reperfusion to the current standard of care is required. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov . Unique identifier: NCT03000270.
Assuntos
Infarto Miocárdico de Parede Anterior/terapia , Coração Auxiliar , Reperfusão Miocárdica/métodos , Implantação de Prótese/instrumentação , Infarto do Miocárdio com Supradesnível do Segmento ST/terapia , Função Ventricular Esquerda , Adulto , Idoso , Idoso de 80 Anos ou mais , Infarto Miocárdico de Parede Anterior/diagnóstico por imagem , Infarto Miocárdico de Parede Anterior/fisiopatologia , Transtornos Cerebrovasculares/etiologia , Transtornos Cerebrovasculares/fisiopatologia , Transtornos Cerebrovasculares/prevenção & controle , Estudos de Viabilidade , Feminino , Humanos , Imagem Cinética por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Reperfusão Miocárdica/efeitos adversos , Traumatismo por Reperfusão Miocárdica/etiologia , Traumatismo por Reperfusão Miocárdica/fisiopatologia , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Projetos Piloto , Estudos Prospectivos , Implantação de Prótese/efeitos adversos , Recuperação de Função Fisiológica , Recidiva , Fatores de Risco , Infarto do Miocárdio com Supradesnível do Segmento ST/diagnóstico por imagem , Infarto do Miocárdio com Supradesnível do Segmento ST/fisiopatologia , Fatores de Tempo , Resultado do Tratamento , Estados Unidos , Adulto JovemRESUMO
A 56-year-old woman with non-ischaemic cardiomyopathy with implantable cardioverter defibrillator (ICD) presented to the hospital with progressive dyspnoea of 4 weeks' duration. She soon spiralled down to develop septic shock with methicillin-sensitive Staphylococcus aureus bacteraemia. A transoesophageal echocardiogram revealed a 2.4×2.1 cm large mobile echodensity in the right atrium likely attached to the ICD lead and to the interatrial septum. Although the ICD along with its leads was extracted, bacteraemia persisted despite appropriate antibiotic therapy. Because of her worsening condition, she underwent a right atrial infected clot extraction by the AngioVac system. Her clinical condition noticeably improved soon after evacuation of the infected clot.
Assuntos
Bacteriemia/complicações , Endocardite Bacteriana/complicações , Cardiopatias/terapia , Choque Séptico/complicações , Infecções Estafilocócicas/complicações , Trombectomia/métodos , Trombose/terapia , Antibacterianos/uso terapêutico , Bacteriemia/terapia , Endocardite Bacteriana/tratamento farmacológico , Endocardite Bacteriana/terapia , Feminino , Cardiopatias/complicações , Humanos , Staphylococcus aureus Resistente à Meticilina , Pessoa de Meia-Idade , Choque Séptico/terapia , Infecções Estafilocócicas/tratamento farmacológico , Infecções Estafilocócicas/terapia , Trombose/complicações , VácuoRESUMO
Ammonia-oxidizing microorganisms are an important source of the greenhouse gas nitrous oxide (N2O) in aquatic environments. Identifying the impact of pH on N2O production by ammonia oxidizers is key to understanding how aquatic greenhouse gas fluxes will respond to naturally occurring pH changes, as well as acidification driven by anthropogenic CO2. We assessed N2O production rates and formation mechanisms by communities of ammonia-oxidizing bacteria (AOB) and archaea (AOA) in a lake and a marine environment, using incubation-based nitrogen (N) stable isotope tracer methods with 15N-labeled ammonium (15[Formula: see text]) and nitrite (15[Formula: see text]), and also measurements of the natural abundance N and O isotopic composition of dissolved N2O. N2O production during incubations of water from the shallow hypolimnion of Lake Lugano (Switzerland) was significantly higher when the pH was reduced from 7.54 (untreated pH) to 7.20 (reduced pH), while ammonia oxidation rates were similar between treatments. In all incubations, added [Formula: see text] was the source of most of the N incorporated into N2O, suggesting that the main N2O production pathway involved hydroxylamine (NH2OH) and/or [Formula: see text] produced by ammonia oxidation during the incubation period. A small but significant amount of N derived from exogenous/added 15[Formula: see text] was also incorporated into N2O, but only during the reduced-pH incubations. Mass spectra of this N2O revealed that [Formula: see text] and 15[Formula: see text] each contributed N equally to N2O by a "hybrid-N2O" mechanism consistent with a reaction between NH2OH and [Formula: see text], or compounds derived from these two molecules. Nitrifier denitrification was not an important source of N2O. Isotopomeric N2O analyses in Lake Lugano were consistent with incubation results, as 15N enrichment of the internal N vs. external N atoms produced site preferences (25.0-34.4) consistent with NH2OH-dependent hybrid-N2O production. Hybrid-N2O formation was also observed during incubations of seawater from coastal Namibia with 15[Formula: see text] and [Formula: see text]. However, the site preference of dissolved N2O here was low (4.9), indicating that another mechanism, not captured during the incubations, was important. Multiplex sequencing of 16S rRNA revealed distinct ammonia oxidizer communities: AOB dominated numerically in Lake Lugano, and AOA dominated in the seawater. Potential for hybrid N2O formation exists among both communities, and at least in AOB-dominated environments, acidification may accelerate this mechanism.
RESUMO
Northern temperate forest soils and Sphagnum-dominated peatlands are a major source and sink of methane. In these ecosystems, methane is mainly oxidized by aerobic methanotrophic bacteria, which are typically found in aerated forest soils, surface peat, and Sphagnum moss. We contrasted methanotrophic bacterial diversity and abundances from the (i) organic horizon of forest soil; (ii) surface peat; and (iii) submerged Sphagnum moss from Cranesville Swamp Preserve, West Virginia, using multiplex sequencing of bacterial 16S rRNA (V3 region) gene amplicons. From ~1 million reads, >50,000 unique OTUs (Operational Taxonomic Units), 29 and 34 unique sequences were detected in the Methylococcaceae and Methylocystaceae, respectively, and 24 potential methanotrophs in the Beijerinckiaceae were also identified. Methylacidiphilum-like methanotrophs were not detected. Proteobacterial methanotrophic bacteria constitute <2% of microbiota in these environments, with the Methylocystaceae one to two orders of magnitude more abundant than the Methylococcaceae in all environments sampled. The Methylococcaceae are also less diverse in forest soil compared to the other two habitats. Nonmetric multidimensional scaling analyses indicated that the majority of methanotrophs from the Methylococcaceae and Methylocystaceae tend to occur in one habitat only (peat or Sphagnum moss) or co-occurred in both Sphagnum moss and peat. This study provides insights into the structure of methanotrophic communities in relationship to habitat type, and suggests that peat and Sphagnum moss can influence methanotroph community structure and biogeography.
RESUMO
BACKGROUND: X-ray use in the catheterization laboratory is guided by the principle of as low as reasonably achievable. In accordance with this principle, we reduced the default fluoroscopic frame rate from 10 to 7.5 frames/s and increased the emphasis on the use of low-dose acquisition starting January 1, 2013. We aimed to study the impact of these measures on the total air kerma during diagnostic catheterization (DC) and percutaneous interventions (PCI). METHODS AND RESULTS: Propensity matching based on age, sex, body surface area, total fluoroscopy time, and total acquisition time was used to select matched patients for 2012 and 2013, further stratified by DC or PCI. The total air kerma was subsequently compared between 2012 and 2013, separately for DC and PCI. Median total air kerma during DC in 2013 was 625 mGy, which was significantly lower than the corresponding values in 2012 (median, 798 mGy; P<0.001). Similarly, median total air kerma during PCI in 2013 was 1675 mGy, which was significantly less than corresponding values in 2012 (median 2463 mGy, P<0.001). On comparison of air kerma rates between corresponding projections in 2 years, we observed a significant reduction in fluoroscopy- and acquisition-based air kerma rates in 2013, after institution of radiation reduction measures in all projections. CONCLUSIONS: With reduction in the default fluoroscopic frame rate and a greater use of low-dose acquisition, there has been a marked reduction in the total air kerma and air kerma rates for DC and PCI.
Assuntos
Cateterismo Cardíaco/métodos , Doenças Cardiovasculares/diagnóstico , Doenças Cardiovasculares/radioterapia , Intervenção Coronária Percutânea/métodos , Idoso , Cateterismo Cardíaco/instrumentação , Exposição Ambiental/efeitos adversos , Feminino , Fluoroscopia , Humanos , Laboratórios Hospitalares , Masculino , Pessoa de Meia-Idade , Intervenção Coronária Percutânea/instrumentação , Melhoria de Qualidade , Doses de Radiação , Radiação Ionizante , Radiografia IntervencionistaRESUMO
The mxaF gene, coding for the large (α) subunit of methanol dehydrogenase, is highly conserved among distantly related methylotrophic species in the Alpha-, Beta- and Gammaproteobacteria. It is ubiquitous in methanotrophs, in contrast to other methanotroph-specific genes such as the pmoA and mmoX genes, which are absent in some methanotrophic proteobacterial genera. This study examined the potential for using the mxaF gene as a functional and phylogenetic marker for methanotrophs. mxaF and 16S rRNA gene phylogenies were constructed based on over 100 database sequences of known proteobacterial methanotrophs and other methylotrophs to assess their evolutionary histories. Topology tests revealed that mxaF and 16S rDNA genes of methanotrophs do not show congruent evolutionary histories, with incongruencies in methanotrophic taxa in the Methylococcaceae, Methylocystaceae, and Beijerinckiacea. However, known methanotrophs generally formed coherent clades based on mxaF gene sequences, allowing for phylogenetic discrimination of major taxa. This feature highlights the mxaF gene's usefulness as a biomarker in studying the molecular diversity of proteobacterial methanotrophs in nature. To verify this, PCR-directed assays targeting this gene were used to detect novel methanotrophs from diverse environments including soil, peatland, hydrothermal vent mussel tissues, and methanotroph isolates. The placement of the majority of environmental mxaF gene sequences in distinct methanotroph-specific clades (Methylocystaceae and Methylococcaceae) detected in this study supports the use of mxaF as a biomarker for methanotrophic proteobacteria.
Assuntos
Oxirredutases do Álcool/genética , Filogenia , Proteobactérias/genética , Clonagem Molecular , Bases de Dados Genéticas , Reação em Cadeia da Polimerase , Proteobactérias/classificaçãoRESUMO
Cambarus (Cambarus) hatfieldi is a stream-dwelling crayfish that appears to be endemic to the Tug Fork River system of West Virginia, Virginia, and Kentucky. Within this region, it is prevalent in all major tributaries in the basin as well as the Tug Fork River's mainstem. The new species is morphologically most similar to Cambarus sciotensis and Cambarus angularis. It can be differentiated from C. sciotensis by its squamous, subtrinagular chelae compared to the elongate triangular chelae of C. sciotensis; its shorter palm length/palm depth ratio (1.9) compared to C. sciotensis (2.3); and a smaller areola length/total carapace length ratio (30.4% vs.36.5% respectively). Cambarus hatfieldi can be differentiated from C. angularis by its smaller areola length/total carapace length ratio (30.4% vs. 36.7% respectively); a smaller rostrum width/rostral length ratio (59.4% vs. 67.2% respectively); its rounded abdominal pleura as compared to the subtruncated pleura of C. angularis; the length of the central projection and mesial process of C. hatfieldi which both extend to the margin of the gonopod shaft or slightly beyond the margin compared to the central projection of C. sciotensis and C. angularis where both extend well beyond the margin of the gonopod shaft.
Assuntos
Astacoidea/classificação , Distribuição Animal , Estruturas Animais/anatomia & histologia , Animais , Astacoidea/anatomia & histologia , Astacoidea/genética , Feminino , Kentucky , Masculino , Dados de Sequência Molecular , Filogenia , Rios , Virginia , West VirginiaRESUMO
Interventions on vein graft occlusions are technically feasible procedures but carry significant risk for periprocedural complications and demonstrate questionable long-term patency. For those circumstances in which recanalization of a graft occlusion is warranted, the authors have highlighted some of the procedural considerations and available techniques that may help maximize chances for success. This should not be mistaken for a wholesale endorsement of vein graft chronic total occlusion interventions. Before undertaking a procedure of this complexity, the operator must put strong consideration into the risks, benefits, and alternatives for a given patient.
RESUMO
This article focuses on the general principles of informed consent, then highlights the particular risks associated with chronic total occlusion interventions. The goal is to provide a basic framework for the interventional cardiologist to use when having consent discussions with his or her patients.
RESUMO
BACKGROUND: Several bone marrow-derived cell populations may have angiogenic activity, including cells termed endothelial progenitor cells. Decreased numbers of circulating angiogenic cell populations have been associated with increased cardiovascular risk. However, few data exist from large, unselected samples, and the genetic determinants of these traits are unclear. METHODS AND RESULTS: We examined the clinical and genetic correlates of early-outgrowth colony-forming units (CFUs) in 1799 participants of the Framingham Heart Study (mean age, 66 years; 54% women). Among individuals without cardiovascular disease (n = 1612), CFU number was inversely related to advanced age (P = 0.004), female sex (P = 0.04), and triglycerides (P = 0.008) and positively related to hormone replacement (P = 0.008) and statin therapy (P = 0.027) in stepwise multivariable analyses. Overall, CFU number was inversely related to the Framingham risk score (P = 0.01) but not with prevalent cardiovascular disease. In genome-wide association analyses in the entire sample, polymorphisms were associated with CFUs at the MOSC1 locus (P = 3.3 × 10(-7)) and at the SLC22A3-LPAL2-LPA locus (P = 4.9 × 10(-7)), a previously replicated susceptibility locus for myocardial infarction. Furthermore, alleles at the SLC22A3-LPAL2-LPA locus that were associated with decreased CFUs were also related to increased risk of myocardial infarction (P = 1.1 × 10(-4)). CONCLUSIONS: In a community-based sample, early-outgrowth CFUs are inversely associated with select cardiovascular risk factors. Furthermore, genetic variants at the SLC22A3-LPAL2-LPA locus are associated with both decreased CFUs and an increased risk of myocardial infarction. These findings are consistent with the hypothesis that decreased circulating angiogenic cell populations promote susceptibility to myocardial infarction.
Assuntos
Células da Medula Óssea , Doenças Cardiovasculares/fisiopatologia , Células Endoteliais , Células-Tronco , Idoso , Células da Medula Óssea/citologia , Células da Medula Óssea/fisiologia , Células Endoteliais/citologia , Células Endoteliais/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Fatores de Risco , Células-Tronco/citologia , Células-Tronco/fisiologiaAssuntos
Doença das Coronárias/terapia , Hipotermia Induzida/efeitos adversos , Veia Cava Inferior , Trombose Venosa/etiologia , Reanimação Cardiopulmonar , Angiografia Coronária , Ponte de Artéria Coronária , Doença das Coronárias/diagnóstico , Eletrocardiografia , Humanos , Hipotermia Induzida/instrumentação , Masculino , Pessoa de Meia-Idade , Trombose Venosa/terapiaRESUMO
The hydrothermal vent clam Calyptogena magnifica (Bivalvia: Mollusca) is a member of the Vesicomyidae. Species within this family form symbioses with chemosynthetic Gammaproteobacteria. They exist in environments such as hydrothermal vents and cold seeps and have a rudimentary gut and feeding groove, indicating a large dependence on their endosymbionts for nutrition. The C. magnifica symbiont, Candidatus Ruthia magnifica, was the first intracellular sulfur-oxidizing endosymbiont to have its genome sequenced (Newton et al. 2007). Here we expand upon the original report and provide additional details complying with the emerging MIGS/MIMS standards. The complete genome exposed the genetic blueprint of the metabolic capabilities of the symbiont. Genes which were predicted to encode the proteins required for all the metabolic pathways typical of free-living chemoautotrophs were detected in the symbiont genome. These include major pathways including carbon fixation, sulfur oxidation, nitrogen assimilation, as well as amino acid and cofactor/vitamin biosynthesis. This genome sequence is invaluable in the study of these enigmatic associations and provides insights into the origin and evolution of autotrophic endosymbiosis.
Assuntos
Adenocarcinoma/complicações , Anticoagulantes/efeitos adversos , Dalteparina/efeitos adversos , Neoplasias Pulmonares/complicações , Dermatopatias/induzido quimicamente , Adenocarcinoma/secundário , Feminino , Humanos , Neoplasias Hepáticas/complicações , Neoplasias Hepáticas/secundário , Neoplasias Pulmonares/patologia , Pessoa de Meia-Idade , Necrose , Embolia Pulmonar/tratamento farmacológico , Dermatopatias/patologia , Trombose Venosa/tratamento farmacológicoRESUMO
Methanotroph abundance was analyzed in control and long-term nitrogen-amended pine and hardwood soils using rRNA-targeted quantitative hybridization. Family-specific 16S rRNA and pmoA/amoA genes were analyzed via PCR-directed assays to elucidate methanotrophic bacteria inhabiting soils undergoing atmospheric methane consumption. Quantitative hybridizations suggested methanotrophs related to the family Methylocystaceae were one order of magnitude more abundant than Methyloccocaceae and more sensitive to nitrogen-addition in pine soils. 16S rRNA gene phylotypes related to known Methylocystaceae and acidophilic methanotrophs and pmoA/amoA gene sequences, including three related to the upland soil cluster Alphaproteobacteria (USCalpha) group, were detected across different treatments and soil depths. Our results suggest that methanotrophic members of the Methylocystaceae and Beijerinckiaceae may be the candidates for soil atmospheric methane consumption.
Assuntos
Alphaproteobacteria/metabolismo , Metano/metabolismo , Methylocystaceae/metabolismo , Microbiologia do Solo , Alphaproteobacteria/genética , Proteínas de Bactérias/genética , DNA Bacteriano/genética , DNA Ribossômico/genética , Methylocystaceae/genética , Dados de Sequência Molecular , Nitrogênio/metabolismo , Hibridização de Ácido Nucleico , Filogenia , RNA Ribossômico 16S/genéticaRESUMO
beta-Carotene and its metabolites exert a broad range of effects, in part by regulating transcriptional responses through specific nuclear receptor activation. Symmetric cleavage of beta-carotene can yield 9-cis retinoic acid (9-cisRA), the natural ligand for the nuclear receptor RXR, the obligate heterodimeric partner for numerous nuclear receptor family members. A significant portion of beta-carotene can also undergo asymmetric cleavage to yield apocarotenals, a series of poorly understood naturally occurring molecules whose biologic role, including their transcriptional effects, remains essentially unknown. We show here that beta-apo-14'-carotenal (apo14), but not other structurally related apocarotenals, represses peroxisome proliferator-activated receptors (PPAR) and RXR activation and biologic responses induced by their respective agonists both in vitro and in vivo. During adipocyte differentiation, apo14 inhibited PPARgamma target gene expression and adipogenesis, even in the presence of the potent PPARgamma agonist BRL49653. Apo14 also suppressed known PPARalpha responses, including target gene expression and its known antiinflammatory effects, but not if PPARalpha agonist stimulation occurred before apo14 exposure and not in PPARalpha-deficient cells or mice. Other apocarotenals tested had none of these effects. These data extend current views of beta-carotene metabolism to include specific apocarotenals as possible biologically active mediators and identify apo14 as a possible template for designing PPAR and RXR modulators and better understanding modulation of nuclear receptor activation. These results also suggest a novel model of molecular endocrinology in which metabolism of a parent compound, beta-carotene, may alternatively activate (9-cisRA) or inhibit (apo14) specific nuclear receptor responses.
Assuntos
Receptores Ativados por Proliferador de Peroxissomo/química , Receptores X de Retinoides/química , beta Caroteno/química , Células 3T3-L1 , Adipócitos/metabolismo , Animais , Núcleo Celular/metabolismo , Regulação da Expressão Gênica , Humanos , Masculino , Camundongos , Modelos Químicos , Ligação Proteica , Estrutura Terciária de Proteína , Transcrição GênicaRESUMO
Lithified coniform structures are common within cyanobacterial mats in Yellowstone National Park hot springs. It is unknown whether these structures and the mats from which they develop are inhabited by the same cyanobacterial populations. Denaturing gradient gel electrophoresis and sequencing and phylogenetic analysis of 16S rDNA was used to determine whether (1) three different morphological types of lithified coniform structures are inhabited by different cyanobacterial species, (2) these species are partitioned along a vertical gradient of these structures, and (3) lithified and non-lithified sections of mat are inhabited by different cyanobacterial species. Our results, based on multiple samplings, indicate that the cyanobacterial community compositions in the three lithified morphological types were identical and lacked any vertical differentiation. However, lithified and non-lithified portions of the same mat were inhabited by distinct and different populations of cyanobacteria. Cyanobacteria inhabiting lithified structures included at least one undefined Oscillatorialean taxon, which may represent the dominant cyanobacteria genus in lithified coniform stromatolites, Phormidium, three Synechococcus-like species, and two unknown cyanobacterial taxa. In contrast, the surrounding mats contained four closely related Synechococcus-like species. Our results indicate that the distribution of lithified coniform stromatolites may be dependent on the presence of one or more microorganisms, which are phylogenetically different from those inhabiting surrounding non-lithified mats.