RESUMEN
Postoperative pain and delayed healing in surgical wounds, which require complex management strategies have understudied complicated mechanisms. Here we investigated temporal changes in behavior, tissue structure, and transcriptomic profiles in a rat model of a surgical incision, using hyperalgesic behavioral tests, histological analyses, and next-generation RNA sequencing, respectively. The most rapidly (1 hour) expressed genes were the chemokines, Cxcl1 and Cxcl2. Consequently, infiltrating leukocytes were abundantly observed starting at 6 and peaking at 24 hours after incising which was supported by histological analysis and appearance of the neutrophil markers, S100a8 and S100a9. At this time, hyperalgesia was at a peak and overall transcriptional activity was most highly activated. At the 1-day timepoint, Nppb, coding for natriuretic peptide precursor B, was the most strongly upregulated gene and was localized by in situ hybridization to the epidermal keratinocytes at the margins of the incision. Nppb was basically unaffected in a peripheral inflammation model transcriptomic dataset. At the late phase of wound healing, five secreted, incision-specific peptidases, Mmp2, Aebp1, Mmp23, Adamts7, and Adamtsl1, showed increased expression, supporting the idea of a sustained tissue remodeling process. Transcripts that are specifically upregulated at each timepoint in the incision model may be potential candidates for either biomarkers or therapeutic targets for wound pain and wound healing. This study incorporates the examination of longitudinal temporal molecular responses, corresponding anatomical localization, and hyperalgesic behavioral alterations in the surgical incision model that together provide important and novel foundational knowledge to understand mechanisms of wound pain and wound healing.
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Hiperalgesia/patología , Dolor Postoperatorio/patología , Placa Plantar/fisiología , RNA-Seq/métodos , Herida Quirúrgica/complicaciones , Transcriptoma , Cicatrización de Heridas , Animales , Conducta Animal , Edema/etiología , Edema/metabolismo , Edema/patología , Hiperalgesia/etiología , Hiperalgesia/metabolismo , Inflamación/etiología , Inflamación/metabolismo , Inflamación/patología , Masculino , Dolor Postoperatorio/etiología , Dolor Postoperatorio/metabolismo , Ratas , Ratas Sprague-DawleyRESUMEN
Despite decades of research and an enormity of resultant data, cancer remains a significant public health problem. New tools and fresh perspectives are needed to obtain fundamental insights, to develop better prognostic and predictive tools, and to identify improved therapeutic interventions. With increasingly common genome-scale data, one suite of algorithms and concepts with potential to shed light on cancer biology is phylogenetics, a scientific discipline used in diverse fields. From grouping subsets of cancer samples to tracing subclonal evolution during cancer progression and metastasis, the use of phylogenetics is a powerful systems biology approach. Well-developed phylogenetic applications provide fast, robust approaches to analyze high-dimensional, heterogeneous cancer data sets. This article is part of a Special Issue entitled: Evolutionary principles - heterogeneity in cancer?, edited by Dr. Robert A. Gatenby.
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Biomarcadores de Tumor/genética , Transformación Celular Neoplásica/genética , Evolución Molecular , Aptitud Genética , Neoplasias/genética , Filogenia , Adaptación Fisiológica , Algoritmos , Animales , Biomarcadores de Tumor/metabolismo , Transformación Celular Neoplásica/metabolismo , Transformación Celular Neoplásica/patología , Regulación Neoplásica de la Expresión Génica , Predisposición Genética a la Enfermedad , Genómica/métodos , Herencia , Humanos , Modelos Genéticos , Mutación , Neoplasias/tratamiento farmacológico , Neoplasias/metabolismo , Neoplasias/patología , Linaje , Fenotipo , Transducción de Señal/genética , Biología de Sistemas , Factores de TiempoRESUMEN
Demosponges share eight orthologous microRNAs (miRNAs), with none in common with Bilateria. Biological functions of these demosponge miRNAs are unknown. Bilaterian miRNAs are key regulators of cellular processes including cell cycle, differentiation, and metabolism. Resolving if demosponge miRNAs participate in such biological functions will provide clues whether these functions are convergent, evidence on the mode of evolution of cellular developmental processes. Here, a quantitative PCR (qPCR) assay was developed and used to test for differential miRNA expression during dissociation and reaggregation in Spongosorites, compare expression profiles between choanosome and cortex in Spongosorites, and compare undifferentiated gemmules to differentiated juveniles in Ephydatia. During Spongosorites dissociation and reaggregation, miRNA expression showed a global decrease in expression across a range of reaggregating cell densities. miRNA differential response could be related to various general cellular responses, potentially related to nutrient-poor conditions of the minimal artificial seawater media, stress response from tissue dissociation, or loss of cell-cell or cell-matrix contact. In Ephydatia, overall increase in miRNA expression in gemmule-hatched stage 4/5 juveniles relative to gemmules is observed, indicating that increased miRNA expression may be related to increased cellular activity such as migration, cell cycle, and/or differentiation. Observed differential miRNA expression of miRNA during dissociation in Spongosorites (lowered global expression), and during activation, and differentiation of Ephydatia gemmules (increased global expression) could indicate that miRNA expression is associated with cell cycle, differentiation, or metabolism pathways. Interspecies comparison was performed, results indicating that orthologous miRNAs share similar relative expression pattern between the four species tested (Spongosorites, Cinachyrella, Haliclona, and Ephydatia), demonstrating and evolutionarily conserved miRNA expression profile across Demospongia. While these results do not elucidate specific molecular and cellular pathways, together they provide a broad survey of miRNA expression in demosponge systems.
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Evolución Molecular , Regulación del Desarrollo de la Expresión Génica , MicroARNs/genética , Poríferos/genética , Transcriptoma , Animales , Perfilación de la Expresión Génica/métodos , Poríferos/clasificación , Poríferos/crecimiento & desarrollo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Especificidad de la EspecieRESUMEN
microRNAs (miRNAs) are a key component of gene regulatory networks and have been implicated in the regulation of virtually every biological process found in multicellular eukaryotes. What makes them interesting from a phylogenetic perspective is the high conservation of primary sequence between taxa, their accrual in metazoan genomes through evolutionary time, and the rarity of secondary loss in most metazoan taxa. Despite these properties, the use of miRNAs as phylogenetic markers has not yet been discussed within a clear conceptual framework. Here we highlight five properties of miRNAs that underlie their utility in phylogenetics: 1) The processes of miRNA biogenesis enable the identification of novel miRNAs without prior knowledge of sequence; 2) The continuous addition of miRNA families to metazoan genomes through evolutionary time; 3) The low level of secondary gene loss in most metazoan taxa; 4) The low substitution rate in the mature miRNA sequence; and 5) The small probability of convergent evolution of two miRNAs. Phylogenetic analyses using both Bayesian and parsimony methods on a eumetazoan miRNA data set highlight the potential of miRNAs to become an invaluable new tool, especially when used as an additional line of evidence, to resolve previously intractable nodes within the tree of life.
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Evolución Molecular , MicroARNs/genética , MicroARNs/metabolismo , Filogenia , Animales , Secuencia de Bases , Teorema de Bayes , Secuencia Conservada , Redes Reguladoras de Genes , Genoma , Humanos , Metabolismo Secundario/genética , Especificidad de la EspecieRESUMEN
We present the discovery of microRNAs (miRNAs) in the calcisponges Sycon and Leucosolenia (phylum Calcarea), and potential miRNAs in the homoscleromorph Oscarella carmela (Phylum Homoscleromorpha), expanding the complement of poriferan miRNAs previously known only from the siliceous sponges (demosponges and hexactinellids). Comparison of these miRNAs with those previously described from silicisponges and eumetazoans reveals that these newly described miRNAs are novel, with each metazoan lineage (Silicea, Calcarea, Homoscleromorpha, and Eumetazoa) characterized by a unique and non-overlapping repertoire of miRNAs (or potential miRNAs as in the case of the homoscleromorphs). Because each group is characterized by a unique repertoire of miRNAs, miRNAs cannot be used to help resolve the contentious issue of sponge mono- versus paraphyly. Further, because all sponges are characterized by a similar repertoire of tissue types and body plan organisation, we hypothesize that the lack of conserved miRNAs amongst the three primary sponge lineages is evidence that cellular differentiation and cell type specificity in sponges are not dependent upon conserved miRNAs, contrary to many known cases in eumetazoans. Finally, we suggest that miRNAs evolved multiple times independently not only among eukaryotes, but even within animals, independently evolved miRNAs representing molecular exaptations of RNAi machinery into pre-existing gene regulatory networks. The role(s) miRNAs play though in sponge biology and evolution remains an open question.
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Evolución Molecular , MicroARNs/análisis , Animales , Secuencia de Bases , Teorema de Bayes , MicroARNs/genética , Datos de Secuencia Molecular , Filogenia , Homología de Secuencia de AminoácidoRESUMEN
BACKGROUND: Persons with HIV (PWHIV) on highly active antiretroviral treatments (HAART) may require specialized care based on health and demographic indicators. This study investigated the association of comorbidities, race, weight status, and gastrointestinal (GI) and cardiovascular (CV) symptoms among PWHIV. METHODS: The Symptom Checklist, Co-Morbidity Questionnaire, and Sociodemographic Questionnaire were used to assess weight status and GI and CV symptoms among 283 PWHIV. Data were analyzed using latent class analysis on John's Macintosh Project 13 Platform. RESULTS: Participants were majority Black (50%), 69% male, and 35% AIDS diagnosed. Ages were 25 to 66. Clusters included least symptomatic status, weight gain, and weight loss by Black and non-Black participants. The non-Black weight gain cluster reported a higher incidence of AIDS (70.6% vs 38.2%), nausea (70.6% vs 17.6%), diarrhea (70.6% vs 26.5%), and shortness of breath (58.8% vs 20.6%) compared to the Black weight gain cluster. The Black weight loss cluster reported a higher incidence of CV symptoms such as chest palpitations (42.2% vs 2.7%), chest pain (44.4% vs 8.1%), and shortness of breath (73.3% vs 35.1%). Moreover, the Black weight loss cluster reported a higher incidence of all GI symptoms with the most prominent being diarrhea (71.1% vs 48.6%) compared to the non-Black weight loss cluster. CONCLUSIONS: The existing racial disparities in health-related quality of life for PWHIV may be improved through precision health and nutrition modifications. Continued research is needed investigating differential health outcomes among PWHIV on HAART. CLINICAL TRIAL REGISTRATION NUMBER: NCT00222716. Registered 22 September 2005. Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT00222716?term=NCT00222716&draw=2&rank=1.
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Síndrome de Inmunodeficiencia Adquirida , Infecciones por VIH , Cardiopatías , Femenino , Humanos , Masculino , Antirretrovirales/uso terapéutico , Estudios Transversales , VIH , Infecciones por VIH/tratamiento farmacológico , Infecciones por VIH/epidemiología , Calidad de Vida , Estados Unidos/epidemiologíaRESUMEN
Submarine hydrothermal vents are model systems for the Archaean Earth environment, and some sites maintain conditions that may have favored the formation and evolution of cellular life. Vents are typified by rapid fluctuations in temperature and redox potential that impose a strong selective pressure on resident microbial communities. Nautilia profundicola strain Am-H is a moderately thermophilic, deeply-branching Epsilonproteobacterium found free-living at hydrothermal vents and is a member of the microbial mass on the dorsal surface of vent polychaete, Alvinella pompejana. Analysis of the 1.7-Mbp genome of N. profundicola uncovered adaptations to the vent environment--some unique and some shared with other Epsilonproteobacterial genomes. The major findings included: (1) a diverse suite of hydrogenases coupled to a relatively simple electron transport chain, (2) numerous stress response systems, (3) a novel predicted nitrate assimilation pathway with hydroxylamine as a key intermediate, and (4) a gene (rgy) encoding the hallmark protein for hyperthermophilic growth, reverse gyrase. Additional experiments indicated that expression of rgy in strain Am-H was induced over 100-fold with a 20 degrees C increase above the optimal growth temperature of this bacterium and that closely related rgy genes are present and expressed in bacterial communities residing in geographically distinct thermophilic environments. N. profundicola, therefore, is a model Epsilonproteobacterium that contains all the genes necessary for life in the extreme conditions widely believed to reflect those in the Archaean biosphere--anaerobic, sulfur, H2- and CO2-rich, with fluctuating redox potentials and temperatures. In addition, reverse gyrase appears to be an important and common adaptation for mesophiles and moderate thermophiles that inhabit ecological niches characterized by rapid and frequent temperature fluctuations and, as such, can no longer be considered a unique feature of hyperthermophiles.
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Adaptación Fisiológica/genética , Epsilonproteobacteria/genética , Genoma Bacteriano , Archaea/genética , Archaea/crecimiento & desarrollo , Carbono/metabolismo , Replicación del ADN , ADN de Archaea/metabolismo , Ecosistema , Epsilonproteobacteria/crecimiento & desarrollo , Nitrógeno/metabolismo , Oxidación-Reducción , Filogenia , Agua de Mar , Transducción de Señal , Azufre/metabolismo , TemperaturaRESUMEN
BACKGROUND: Irritable bowel syndrome (IBS) is a chronic gastrointestinal condition predominantly affecting the female sex, and is characterized by brain-gut axis dysregulation. Relevance of hormones along the hypothalamic-pituitary gonadal axis and hypothalamic-pituitary adrenal axis to IBS symptomatology remain unclear, as does the significance of other modulators including brain derived neurotrophic factor (BDNF), leptin, and transforming growth factor ßeta 1 (TGF-ß1). METHODS: Females with IBS were compared with female healthy controls (HC) on age, race, hormonal contraceptive use, body mass index, adrenocorticotropic hormone, cortisol, estradiol, follicular stimulating hormone, luteinizing hormone, progesterone, total cholesterol, Center for Epidemiological Studies Depression Scale (CES-D) and Perceived Stress Scale (PSS). BDNF, leptin, and TGF-ß1 were quantified using enzyme-linked immunosorbent assay. Descriptive statistics, non-parametric techniques, and regression analyses were performed. RESULTS: Participants with IBS (n = 12) displayed higher estradiol (p = .027) than did HC (n = 21). Direction of associations among study variables often differed between groups: BDNF and progesterone in HC (rs = .623) and in IBS (rs = -.723). The relationship between log (CES-D) and log (estradiol) varied by IBS status (interaction term p = 0.019). DISCUSSION: Elevated estradiol in participants with IBS, and differential patterns of biological and psychological indices between groups, encourages further inquiry on the relevance of sex hormones, BDNF, leptin, and TGF-ß1 to symptoms of IBS. Future research endeavors should conduct longitudinal quantification of sex hormones with subjective symptom assessment to facilitate insight on the pathophysiology and female sex bias in IBS.
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Factor Neurotrófico Derivado del Encéfalo/sangre , Hormonas Esteroides Gonadales/sangre , Síndrome del Colon Irritable/sangre , Leptina/sangre , Factor de Crecimiento Transformador beta1/sangre , Hormona Adrenocorticotrópica/sangre , Adulto , Depresión/sangre , Depresión/psicología , Femenino , Humanos , Hidrocortisona/sangre , Síndrome del Colon Irritable/psicología , Proyectos PilotoRESUMEN
Pain is a common but potentially debilitating symptom, often requiring complex management strategies. To understand the molecular dynamics of peripheral inflammation and nociceptive pain, we investigated longitudinal changes in behavior, tissue structure, and transcriptomic profiles in the rat carrageenan-induced peripheral inflammation model. Sequential changes in the number of differentially expressed genes are consistent with temporal recruitment of key leukocyte populations, mainly neutrophils and macrophages with each wave being preceded by upregulation of the cell-specific chemoattractants, Cxcl1 and Cxcl2, and Ccl2 and Ccl7, respectively. We defined 12 temporal gene clusters based on expression pattern. Within the patterns we extracted genes comprising the inflammatory secretome and others related to nociceptive tissue remodeling and to sensory perception of pain. Structural tissue changes, involving upregulation of multiple collagens occurred as soon as 1-hour postinjection, consistent with inflammatory tissue remodeling. Inflammatory expression profiling revealed a broad-spectrum, temporally orchestrated molecular and cellular recruitment process. The results provide numerous potential targets for modulation of pain and inflammation. PERSPECTIVE: This study investigates the highly orchestrated biological response during tissue inflammation with precise assessment of molecular dynamics at the transcriptional level. The results identify transcriptional changes that define an evolving inflammatory state in rats. This study provides foundational data for identifying markers of, and potential treatments for, inflammation and pain in patients.
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Perfilación de la Expresión Génica , Hiperalgesia/inmunología , Inmunidad Innata/inmunología , Inflamación/inmunología , Dolor Nociceptivo/inmunología , Secretoma/inmunología , Animales , Carragenina/farmacología , Modelos Animales de Enfermedad , Pie , Hiperalgesia/inducido químicamente , Inflamación/inducido químicamente , Masculino , Dolor Nociceptivo/inducido químicamente , Ratas , Ratas Sprague-Dawley , Análisis de Secuencia de ARNRESUMEN
Yersinia pestis proteins were sequentially extracted from crude membranes with a high salt buffer (2.5 M NaBr), an alkaline solution (180 mM Na2CO3, pH 11.3) and membrane denaturants (8 M urea, 2 M thiourea and 1% amidosulfobetaine-14). Separation of proteins by 2D gel electrophoresis was followed by identification of more than 600 gene products by MS. Data from differential 2D gel display experiments, comparing protein abundances in cytoplasmic, periplasmic and all three membrane fractions, were used to assign proteins found in the membrane fractions to three protein categories: (i) integral membrane proteins and peripheral membrane proteins with low solubility in aqueous solutions (220 entries); (ii) peripheral membrane proteins with moderate to high solubility in aqueous solutions (127 entries); (iii) cytoplasmic or ribosomal membrane-contaminating proteins (80 entries). Thirty-one proteins were experimentally associated with the outer membrane (OM). Circa 50 proteins thought to be part of membrane-localized, multi-subunit complexes were identified in high Mr fractions of membrane extracts via size exclusion chromatography. This data supported biologically meaningful assignments of many proteins to the membrane periphery. Since only 32 inner membrane (IM) proteins with two or more predicted transmembrane domains (TMDs) were profiled in 2D gels, we resorted to a proteomic analysis by 2D-LC-MS/MS. Ninety-four additional IM proteins with two or more TMDs were identified. The total number of proteins associated with Y. pestis membranes increased to 456 and included representatives of all six beta-barrel OM protein families and 25 distinct IM transporter families.
RESUMEN
The periplasmic proteome of Yersinia pestis strain KIM6+ was characterized using differential 2-DE display of proteins isolated from several subcellular fractions. Circa 160 proteins were designated as periplasmic, including 62 (putative) solute-binding proteins of ATP-binding cassette (ABC) transporters (SBPs) and 46 (putative) metabolic enzymes. More than 30 SBPs were significantly increased in abundance during stationary phase cell growth, compared to the exponential phase. The data suggest that nutrient exhaustion in the stationary phase triggers cellular responses resulting in the induced expression of numerous ABC transporters, which are responsible for the import of solutes/nutrients. Limited availability of inorganic phosphate (P(i)) also caused dramatic proteomic changes. Nine proteins were functionally linked to the mobilization and import of three small molecules (P(i), phosphonate and glycerol-3-phosphate) and accounted for nearly half of the total protein mass in the periplasm of P(i)-starved cells. When cells were grown at 26 degrees C versus 37 degrees C, corresponding to ambient temperatures in the flea vector and mammalian hosts, respectively, several periplasmic proteins with no known roles in the Y. pestis life cycle were strongly altered in abundance. This included a putative nitrate/sulfonate/bicarbonate-specific SBP (Y1004), encoded by the virulence-associated plasmid pMT1 and increased in abundance at 37 degrees C.
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Proteínas Bacterianas/química , Proteínas Periplasmáticas/química , Yersinia pestis/química , Permeabilidad de la Membrana Celular , Medios de Cultivo , Electroforesis en Gel Bidimensional , Fosfatos/metabolismo , Proteómica/métodos , Temperatura , Yersinia pestis/crecimiento & desarrolloRESUMEN
Background & Aims: Intestinal barrier alterations are associated with fatty liver (FL) and metabolic syndrome (MetS), but microRNA (miR) signaling pathways in MetS-FL pathogenesis remain unclear. This study investigates an epithelial-focused miR network in colorectal cell models based on the previously reported MetS-FL miR trio of hsa-miR-142-3p, hsa-miR-18b, and hsa-miR-890. Methods: Each miR mimic construct of MetS-FL miR trio was transfected into human colorectal cells, CRL-1790 or Caco-2. Global miRNome changes posttransfection were profiled (nCounter® Human v3 miRNA, NanoString Technologies). Changes in barrier (transepithelial electrical resistance, TEER) and epithelial cell junction structure (Occludin and Zona Occludens-1/ZO-1 immunofluorescence staining-confocal microscopy) were examined pre- and posttransfection in Caco-2 cell monolayers. A signaling network was constructed from the MetS-FL miR trio, MetS-FL miR-induced colorectal miRNome changes, ZO-1, and Occludin. Results: Transfection of CRL-1790 cells with each MetS-FL miR mimic led to global changes in the cellular miRNome profile, with 288 miRs being altered in expression by more than twofold. Eleven miRs with known cytoskeletal and metabolic roles were commonly altered in expression by all three miR mimics. Transfection of Caco-2 cell monolayers with each MetS-FL miR mimic induced barrier-associated TEER variations and led to structural modifications of ZO-1 and Occludin within epithelial cell junctions. Pathway analysis incorporating the MetS-FL miR trio, eleven common target miRs, ZO-1, and Occludin revealed a signaling network centered on TNF and AKT2, which highlights injury, inflammation, and hyperplasia. Conclusions: Colon-specific changes in epithelial barriers, cell junction structure, and a miRNome signaling network are described from functional studies of a MetS-FL miR trio signature.
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Células Epiteliales/fisiología , Hígado Graso/metabolismo , Uniones Intercelulares/ultraestructura , Síndrome Metabólico/metabolismo , MicroARNs/metabolismo , Transducción de Señal , Células CACO-2 , Colon , Impedancia Eléctrica , Células Epiteliales/metabolismo , Humanos , Uniones Intercelulares/metabolismo , MicroARNs/genética , Microscopía Confocal , Ocludina/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Transfección , Factor de Necrosis Tumoral alfa/metabolismo , Proteína de la Zonula Occludens-1/metabolismoRESUMEN
Yersinia pestis cells were grown in vitro at 26 and 37 degrees C, the ambient temperatures of its flea vector and its mammalian hosts, respectively, and subjected to subcellular fractionation. Abundance changes at 26 vs 37 degrees C were observed for many outer-membrane (OM) proteins. The cell adhesion protein Ail (y1324) and three putative small beta-barrel OM proteins (y1795, y2167 and y4083) were strongly increased at 37 degrees C. The Ail/Lom family protein y1682 (OmpX) was strongly increased at 26 degrees C. Several porins and TonB-dependent receptors, which control small molecule transport through the OM, were also altered in abundance in a temperature-dependent manner. These marked differences in the composition of the OM proteome are probably important for the adaptation of Y. pestis to its in vivo life stages. Thirteen proteins that appear to be part of an intact type VI secretion system (T6SS) were identified in membrane fractions of stationary-phase cells grown at 26 degrees C, but not at 37 degrees C. The corresponding genes are clustered in the Y. pestis KIM gene locus y3658-y3677. The proteins y3674 and y3675 were particularly abundant and co-fractionated in a Mr range indicative of participation in a multi-subunit complex. The soluble haemolysin-coregulated protein y3673 was even more abundant. Its release into the extracellular medium was triggered by treatment of Y. pestis cells with trypsin. Proteases and other stress-response-inducing factors may constitute environmental cues resulting in the activation of the T6SS in Y. pestis.
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Proteínas de la Membrana Bacteriana Externa/metabolismo , Regulación Bacteriana de la Expresión Génica , Proteómica , Yersinia pestis/química , Yersinia pestis/crecimiento & desarrollo , Proteínas de la Membrana Bacteriana Externa/química , Proteínas de la Membrana Bacteriana Externa/genética , Electroforesis en Gel Bidimensional , Transporte de Proteínas , Temperatura , Yersinia pestis/genética , Yersinia pestis/metabolismoRESUMEN
Extraction of crude membrane fractions with alkaline solutions, such as 100-200 mM Na(2)CO(3) (pH ~11), is often used to solubilize peripheral membrane proteins. Integral membrane proteins are largely retained in membrane pellets. We applied this method to the fractionation of membrane proteins of the plague bacterium Yersinia pestis. Extensive horizontal spot trains were observed in 2-DE gels. The pI values of the most basic spots part of such protein spot trains usually matched the computationally predicted pI values. Regular patterns of decreasing spot pI values and in silico analysis with the software ProMoST suggested ;n-1' deamidations of asparagine (N) and/or glutamine (Q) side chains for ;n' observed spots of a protein in a given spot train. MALDI-MS analysis confirmed the occurrence of deamidations, particularly in N side chains part of NG dipeptide motifs. In more than ten cases, tandem MS data for tryptic peptides provided strong evidence for deamidations, with y- and b-ion series increased by 1 Da following N-to-D substitutions. Horizontal spot trains in 2-DE gels were rare when alkaline extraction was omitted during membrane protein sample preparation. This study strongly supports the notion that exposure to alkaline pH solutions is a dominant cause of extensive N and Q side chain deamidations in proteins during sample preparation of membrane extracts. The modifications are of non-enzymatic nature and not physiologically relevant. Therefore, quantitative spot differences within spot trains in differential protein display experiments following the aforementioned sample preparation steps need to be interpreted cautiously.
RESUMEN
Dehalococcoides ethenogenes is the only bacterium known to reductively dechlorinate the groundwater pollutants, tetrachloroethene (PCE) and trichloroethene, to ethene. Its 1,469,720-base pair chromosome contains large dynamic duplicated regions and integrated elements. Genes encoding 17 putative reductive dehalogenases, nearly all of which were adjacent to genes for transcription regulators, and five hydrogenase complexes were identified. These findings, plus a limited repertoire of other metabolic modes, indicate that D. ethenogenes is highly evolved to utilize halogenated organic compounds and H2. Diversification of reductive dehalogenase functions appears to have been mediated by recent genetic exchange and amplification. Genome analysis provides insights into the organism's complex nutrient requirements and suggests that an ancestor was a nitrogen-fixing autotroph.