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Late-stage anthrax infections are characterized by dysregulated immune responses and hematogenous spread of Bacillus anthracis, leading to extreme bacteremia, sepsis, multiple organ failure, and, ultimately, death. Despite the bacterium being nonhemolytic, some fulminant anthrax patients develop a secondary atypical hemolytic uremic syndrome (aHUS) through unknown mechanisms. We recapitulated the pathology in baboons challenged with cell wall peptidoglycan (PGN), a polymeric, pathogen-associated molecular pattern responsible for the hemostatic dysregulation in anthrax sepsis. Similar to aHUS anthrax patients, PGN induces an initial hematocrit elevation followed by progressive hemolytic anemia and associated renal failure. Etiologically, PGN induces erythrolysis through direct excessive activation of all three complement pathways. Blunting terminal complement activation with a C5 neutralizing peptide prevented the progressive deposition of membrane attack complexes on red blood cells (RBC) and subsequent intravascular hemolysis, heme cytotoxicity, and acute kidney injury. Importantly, C5 neutralization did not prevent immune recognition of PGN and shifted the systemic inflammatory responses, consistent with improved survival in sepsis. Whereas PGN-induced hemostatic dysregulation was unchanged, C5 inhibition augmented fibrinolysis and improved the thromboischemic resolution. Overall, our study identifies PGN-driven complement activation as the pathologic mechanism underlying hemolytic anemia in anthrax and likely other gram-positive infections in which PGN is abundantly represented. Neutralization of terminal complement reactions reduces the hemolytic uremic pathology induced by PGN and could alleviate heme cytotoxicity and its associated kidney failure in gram-positive infections.
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Lesión Renal Aguda/prevención & control , Anemia Hemolítica/prevención & control , Bacillus anthracis/química , Pared Celular/química , Complemento C5/antagonistas & inhibidores , Peptidoglicano/toxicidad , Sepsis/complicaciones , Lesión Renal Aguda/etiología , Lesión Renal Aguda/patología , Anemia Hemolítica/etiología , Anemia Hemolítica/patología , Animales , Carbunco/microbiología , Carbunco/patología , Femenino , Hemólisis , Masculino , Papio , Sepsis/inducido químicamenteRESUMEN
The quantification of entropy in images is a topic of interest that has had different applications in the field of agronomy, product generation and medicine. Some algorithms have been proposed for the quantification of the irregularity present in an image; however, the challenges to overcome in the computational cost involved in large images and the reliable measurements in small images are still topics of discussion. In this research we propose an algorithm, EspEn Graph, which allows the quantification and graphic representation of the irregularity present in an image, revealing the location of the places where there are more or less irregular textures in the image. EspEn is used to calculate entropy because it presents reliable and stable measurements for small size images. This allows an image to be subdivided into small sections to calculate the entropy in each section and subsequently perform the conversion of values to graphically show the regularity present in an image. In conclusion, the EspEn Graph returns information on the spatial regularity that an image with different textures has and the average of these entropy values allows a reliable measure of the general entropy of the image.
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The above article was published online with incorrect figure 1.
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Efforts to develop self-replicating nucleic acids have led to insights into the origin of life and have also suggested potential pathways to the design of artificial life forms based on non-natural nucleic acids. The template-directed nonenzymatic polymerization of activated ribonucleotide monomers is generally slow because of the relatively weak nucleophilicity of the primer 3'-hydroxyl. To circumvent this problem, several nucleic acids based on amino-sugar nucleotides have been studied, and as expected, the more-nucleophilic amine generally results in faster primer extension. Extending this logic, we have chosen to study morpholino nucleic acid (MoNA), because the secondary amine of the morpholino-nucleotides is expected to be highly nucleophilic. We describe the synthesis of 2-methylimidazole-activated MoNA monomers from their corresponding ribonucleoside 5'-monophosphates and the synthesis of an RNA primer with a terminal MoNA nucleotide. We show that the activated G and C MoNA monomers enable rapid and efficient extension of the morpholino-terminated primer on homopolymeric and mixed-sequenced RNA templates. Our results show that MoNA is a non-natural informational polymer that is worthy of further study as a candidate self-replicating material.
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Citidina/química , Guanosina/química , Imidazoles/química , Morfolinos/síntesis química , ARN/síntesis química , Morfolinos/química , Conformación de Ácido Nucleico , Polimerizacion , ARN/químicaRESUMEN
PURPOSE: To provide data of the incidence and management of common urological malignancies in renal transplant recipients. MATERIALS AND METHODS: We conducted a retrospective analysis of a prospective database from August 1967 to August 2015. A descriptive analysis of the sample was performed. RESULTS: Among 1256 consecutive RTR a total of 88 patients developed malignancies (7%). There were 18 genitourinary tumors in the 16 patients (20.45% of all malignant neoplasms), incidence of 1.27%. The most common neoplasm encounter was renal cancer (38.8%), followed by urothelial carcinoma (33.3%). Median follow up of transplantation was 197 months (R, 36-336). Mean time from RT to cancer diagnosis 89±70 months (R, 12-276). CsA and AZA was the most common immunosuppression regimen in 68.75%. Mean follow-up after diagnosis was 103±72 months (R 10-215). Recurrence free survival rate of 100%. Overall survival of 89.5% of the sample; there were two non-related cancer deaths during follow up. CONCLUSIONS: The incidence of neoplasms in RTR was lower than in other series, with favorable functional and oncologic results after treatment. This suggests that actions to reduce the risk of these malignancies as well as a strict follow-up are mandatory for an early detection and treatment.
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Trasplante de Riñón/efectos adversos , Neoplasias Urogenitales/epidemiología , Neoplasias Urogenitales/terapia , Adolescente , Adulto , Anciano , Femenino , Humanos , Incidencia , Trasplante de Riñón/estadística & datos numéricos , Masculino , México/epidemiología , Persona de Mediana Edad , Estudios Prospectivos , Estudios Retrospectivos , Adulto JovenRESUMEN
Prostate cancer is the most frequent tumor found in men worldwide and in Mexico in particular. Age and family history are the main risk factors. The diagnosis is made by prostate biopsy in patients with abnormalities detected in their prostate-specific antigen (PSA) levels or digital rectal exam (DRE). This article reviews screening and diagnostic methods as well as treatment options for patients diagnosed with prostate cancer.
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Neoplasias de la Próstata , Antineoplásicos Hormonales/uso terapéutico , Detección Precoz del Cáncer , Humanos , Masculino , Metástasis de la Neoplasia , Antígeno Prostático Específico/sangre , Prostatectomía , Neoplasias de la Próstata/diagnóstico , Neoplasias de la Próstata/epidemiología , Neoplasias de la Próstata/prevención & control , Neoplasias de la Próstata/terapia , Radioterapia Conformacional , Factores de RiesgoRESUMEN
Threose nucleic acid (TNA) is a potential alternative genetic material that may have played a role in the early evolution of life. We have developed a novel synthesis of 2'-amino modified TNA nucleosides (2'-NH2-TNA) based on a cycloaddition reaction between a glycal and an azodicarboxylate, followed by direct nucleosidation of the cycloadduct. Using this route, we synthesized the thymine and guanine 2'-NH2-TNA nucleosides in seven steps with 24% and 12% overall yield, respectively. We then phosphorylated the guanine nucleoside on the 3'-hydroxyl, activated the phosphate as the 2-methylimidazolide, and tested the ability of the activated nucleotide to copy C4 RNA, DNA, and TNA templates by nonenzymatic primer extension. We measured pseudo-first-order rate constants for the first nucleotide addition step of 1.5, 0.97, and 0.57 h(-1) on RNA, DNA, and TNA templates, respectively, at pH 7.5 and 4 °C with 150 mM NaCl, 100 mM N-(hydroxylethyl)imidazole catalyst, and 5 mM activated nucleotide. The activated nucleotide hydrolyzed with a rate constant of 0.39 h(-1), causing the polymerization reaction to stall before complete template copying could be achieved. These extension rates are more than 1 order of magnitude slower than those for amino-sugar ribonucleotides under the same conditions, and copying of the TNA template, which best represented a true self-copying reaction, was the slowest of all. The poor kinetics of 2'-NH2-TNA template copying could give insight into why TNA was ultimately not used as a genetic material by biological systems.
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Desoxirribonucleósidos/síntesis química , Moldes Genéticos , Tetrosas/química , Cristalografía por Rayos X , Reacción de Cicloadición , Desoxirribonucleósidos/química , Desoxirribonucleósidos/genética , Hidrólisis , Estructura Molecular , Tetrosas/genéticaRESUMEN
Background: Eye movements can reflect brain alterations and inform on the presence of motor disabilities and cognitive impairments in people with multiple sclerosis (pwMS). Objective: The aim of the study was to determine the correlation between motor and cognitive measurements and eye movement parameters when performing the n-back task (NBKT). Methods: This was a cross-sectional study carried out at Ramos Mejía Hospital, a center specialized in demyelinating diseases in Buenos Aires, Argentina. The study population consisted of 66 patients with relapsing-remitting multiple sclerosis (RRMS) and 5 patients with secondary progressive multiple sclerosis (SPMS). pwMS performed the n-back test while using a device head mounted display (HMD) with eyetracking capabilities in order to capture eye movement. Clinical motor and cognitive measures were assessed with Expanded Disability Status Scale (EDSS), Nine Hole Peg Test (NHPT), Timed 25-Foot Walk (T25FW), and Symbol Digit Modalities Test (SDMT). Results: pwMS showed strong and statistically significant correlations between gaze duration; number of fixations, saccade amplitude and motor disabilities and cognitive impairments as measured by EDSS, NHPT, T25FW, and SDMT. Conclusion: This study found significant correlations between eye movement behavior and motor and cognitive disability in pwMS. These findings suggest that eye movements have the potential to be used as a surrogate biomarker in MS progression.
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OBJECTIVE: We sought to test whether a 2-week Total Worker Health (TWH) training mapped to TWH education competencies could be administered to a Mexican audience of occupational safety and health professionals and could lead to positive changes to knowledge and behaviors. METHODS: This study used robust program evaluation methods collected before and after each of the nine training days and at the end of the course. RESULTS: Overall course quality received a mean score of 4.6 (SD = 0.6) and 98.8% of participants agreed that their TWH knowledge increased. All participants intended to make at least one change to their professional practice, most frequently helping companies assess their organizational culture to support health, safety, and well-being. CONCLUSIONS: This TWH training was well received and led to positive self-reported increase in knowledge and abilities to influence workers' health, safety, and well-being.
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Salud Laboral , Humanos , México , Salud Laboral/educación , Masculino , Femenino , Adulto , Persona de Mediana Edad , Promoción de la Salud/métodos , Evaluación de Programas y Proyectos de Salud , Conocimientos, Actitudes y Práctica en Salud , Cultura OrganizacionalRESUMEN
[This corrects the article DOI: 10.3389/fimmu.2023.1213920.].
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Introduction: The complement system is a key component of the innate immune system, and its aberrant activation underlies the pathophysiology of various diseases. Zilucoplan is a macrocyclic peptide that binds and inhibits the cleavage/activation of human complement component 5 (C5). We present in vitro and ex vivo data on the mechanism of action of zilucoplan for the inhibition of C5 activation, including two clinically relevant C5 polymorphisms at R885. Methods: The interaction of zilucoplan with C5, including for clinical C5 R885 variants, was investigated using surface plasmon resonance (SPR), hemolysis assays, and ELISA. The interference of C5b6 formation by zilucoplan was investigated by native gel analysis and hemolysis assay. The permeability of zilucoplan in a reconstituted basement membrane was assessed by the partition of zilucoplan on Matrigel-coated transwell chambers. Results: Zilucoplan specifically bound human complement C5 with high affinity, competitively inhibited the binding of C5 to C3b, and blocked C5 cleavage by C5 convertases and the assembly of the cytolytic membrane attack complex (MAC, or C5b9). Zilucoplan fully prevented the in vitro activation of C5 clinical variants at R885 that have been previously reported to respond poorly to eculizumab treatment. Zilucoplan was further demonstrated to interfere with the formation of C5b6 and inhibit red blood cell (RBC) hemolysis induced by plasmin-mediated non-canonical C5 activation. Zilucoplan demonstrated greater permeability than a monoclonal C5 antibody in a reconstituted basement membrane model, providing a rationale for the rapid onset of action of zilucoplan observed in clinical studies. Conclusion: Our findings demonstrate that zilucoplan uses a dual mode of action to potently inhibit the activation of C5 and terminal complement pathway including wild-type and clinical R885 variants that do not respond to eculizumab treatment. These data may be relevant to the clinically demonstrated benefits of zilucoplan.
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Activación de Complemento , Complemento C5 , Hemólisis , Humanos , Anticuerpos Monoclonales , Complemento C5/antagonistas & inhibidoresRESUMEN
This paper aims to review, systematically synthesize, and analyze fragmented information about the importance of coat color in local goats and its relationship with productivity and other important traits. Topics on current research on color expression are addressed, the relationship that has as a mechanism of environmental adaptation, its relationship with the production of meat, milk, and derivates, and the economic value of this characteristic. The use of this attribute as a tool to establish selection criteria in breeding programs based on results reported in the scientific literature is significant, particularly for low-income production systems, where the implementation of classic genetic improvement schemes is limited due to the lack of productive information, which is distinctive of extensive marginal or low scaled production systems around the world.
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One present obstacle to the "RNA-first" model for the origin of life is an inability to generate reasonable "hands off" scenarios for the formation of carbohydrates under conditions where they might have survived for reasonable times once formed. Such scenarios would be especially compelling if they deliver pent(ul)oses, five-carbon sugars found in terran genetics, and exclude other carbohydrates (e.g., aldotetroses) that may also be able to function in genetic systems. Here, we provide detailed chemical analyses of carbohydrate premetabolism, showing how borate, molybdate, and calcium minerals guide the formation of tetroses (C(4)H(8)O(4)), heptoses (C(7)H(14)O(7)), and pentoses (C(5)H(10)O(5)), including the ribose found in RNA, in "hands off" experiments, starting with formaldehyde and glycolaldehyde. These results show that pent(ul)oses would almost certainly have formed as stable borate complexes on the surface of an early Earth beneath a humid CO(2) atmosphere suffering electrical discharge. While aldotetroses form extremely stable complexes with borate, they are not accessible by pathways plausible under the most likely early Earth scenarios. The stabilization by borate is not, however, absolute. Over longer times, material is expected to have passed from borate-bound pent(ul)oses to a branched heptulose, which is susceptible to Cannizzaro reduction to give dead end products. We show how this fate might be avoided using molybdate-catalyzed rearrangement of a branched pentose that is central to borate-moderated cycles that fix carbon from formaldehyde. Our emerging understanding of the nature of the early Earth, including the presence of hydrated rocks undergoing subduction to form felsic magmas in the early Hadean eon, may have made borate and molydate species available to prebiotic chemistry, despite the overall "reduced" state of the planet.
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Carbohidratos/síntesis química , Minerales/química , Prebióticos , Aldehídos/química , Boratos/química , Calcio/química , Carbohidratos/química , Dihidroxiacetona/química , Molibdeno/química , EstereoisomerismoRESUMEN
Complement activation is key to anti-microbial defenses by directly acting on microbes and indirectly by triggering cellular immune responses. Complement activation may also contribute to the pathogenesis of numerous inflammatory and immunological diseases. Consequently, intense research focuses on developing therapeutics that block pathology-causing complement activation while preserving anti-microbial complement activities. However, the pace of research is slowed down significantly by the limitations of current tools for evaluating complement-targeting therapeutics. Moreover, the effects of potential therapeutic agents on innate immune cells, like neutrophils, are not fully understood. Here, we employ microfluidic assays and measure chemotaxis, phagocytosis, and swarming changes in human neutrophils ex vivo in response to various complement-targeting agents. We show that whereas complement factor 5 (C5) cleavage inhibitor eculizumab blocks all neutrophil anti-microbial functions, newer compounds like the C5 cleavage inhibitor RA101295 and C5a receptor antagonist avacopan inhibit chemotaxis and swarming while preserving neutrophil phagocytosis. These results highlight the utility of microfluidic neutrophil assays in evaluating potential complement-targeting therapeutics.
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Compuestos de Anilina/farmacología , Anticuerpos Monoclonales Humanizados/farmacología , Activación de Complemento/efectos de los fármacos , Inactivadores del Complemento/farmacología , Dispositivos Laboratorio en un Chip , Técnicas Analíticas Microfluídicas/instrumentación , Neutrófilos/efectos de los fármacos , Ácidos Nipecóticos/farmacología , Células Cultivadas , Quimiotaxis de Leucocito/efectos de los fármacos , Complemento C3/farmacología , Convertasas de Complemento C3-C5/antagonistas & inhibidores , Convertasas de Complemento C3-C5/metabolismo , Complemento C5a/farmacología , Humanos , Activación Neutrófila/efectos de los fármacos , Neutrófilos/inmunología , Neutrófilos/metabolismo , Fagocitosis/efectos de los fármacos , Receptor de Anafilatoxina C5a/antagonistas & inhibidores , Receptor de Anafilatoxina C5a/metabolismoRESUMEN
OBJECTIVE: To evaluate the systemic action of electroacupuncture and laserpuncture in the repair of excisional cutaneous injuries on the back of adult female Wistar rats. METHODS: Ninety animals were divided into three experimental groups: C-control; E-treated with electroacupuncture [acupoints: Feishu (BL13), Geshu (BL17), Zusanli (ST36)]; L-treated with laserpuncture (same acupoints) and euthanized on the 7th, 14th and 21st days for tissue removal and preparation for histomorphometric and biochemical (dosages, zymography and Western blotting) analysis. RESULTS: The number of fibroblasts in the E and L groups presented higher values than the C on the 14th and 21st days. The number of granulocytes was lower than C on the 21st day in groups E and L. The total number of newly formed vessels increased on the 21st day and was higher in both treatments when compared to C. The birefringent collagen fibers detected on the 21st day was lower in groups E and L than group C. The glycosaminoglycans and hydroxyproline amount was similar among groups throughout the experimental period. The active isoform of matrixmetallo proteinase (MMP)-2 and the latent isoform of MMP-9 did not show any differences among all groups and experimental periods. The amount of collagen â presented higher values in the L group on the 14th day and in the E and L groups on the 21st day. For type III collagen, groups E and L presented values lower than C in all experimental periods. The amount of transforming growth factor-ß1 in the E and L groups showed higher amounts than C on the 7th day and lower on the 14th and 21st days. For vascular endothelial growth factor, E and L groups presented similar and lower values than C on the 7th and 14th days, respectively, and similar on the 21st day. CONCLUSION: The therapies evaluated in this article stimulated fibroblast proliferation, neoangiogenesis and altered the reorganization of collagen fibers in the repair of excisional injuries in female adult rats.
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Electroacupuntura , Terapia por Láser , Piel , Cicatrización de Heridas , Animales , Colágeno , Femenino , Ratas , Ratas Wistar , Piel/lesiones , Factor A de Crecimiento Endotelial Vascular/metabolismoRESUMEN
In the past years, several plant breeding programs have been done to select outstanding genotypes of sideoats grama (Bouteloua curtipendula) for restoration purposes. Such programs have been focused mainly on agronomic traits; however, little attention has been paid to the genetic structure and environmental adaptation of the selected genotypes. Thus, in this study we evaluated the genetic structure of 85 sideoats grama populations in Mexico. In addition, we modeled the past, present and future environmental niche of the genetic clusters of this species. Ninety sideoats grama populations were genetically analyzed through AFLP (Amplified Fragment Length Polymorphisms) markers. The environmental niche of the population clusters was modeled by using the maximum entropy method. The genetic analysis separated the populations into two genetically different clusters (p = 0.0003). The differentiation of these lineages can be partially explained by the paleoclimatic events experienced during the last interglacial and glacial maximums. Consequently, the genetic clusters have different environmental niche at the present time. Suitability areas for the distribution of Cluster I are mainly located in the central part of the country while the environmental niche of Cluster II is located in the semiarid region, close to the mountain range of the Sierra Madre Occidental. Thus, selection and restoration programs with sideoats grama must be carried out using local germplasm from each environmental niche. Given the environmental niche of both genetic clusters will suffer changes in the near and mid-century future, climate change must be considered for genotypes selection and restoration programs.
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Análisis del Polimorfismo de Longitud de Fragmentos Amplificados , Variación Genética , México , Filogenia , Fitomejoramiento , PoaceaeRESUMEN
BACKGROUND: The emergence of COVID-19 and its vertiginous spreading speed represents a unique challenge to neurologists managing multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD). The need for data on the impact of the virus on these patients grows rapidly. There is an urgent necessity of sharing information to enable evidence-based decision making on the clinical management. There are no data on what physicians are doing on clinical practice in Latin American countries. AIM: to investigate current management opinion of Latin American MS and/or NMOSD expert neurologists based on their experience and recommendations. METHODS: we developed a voluntary web-based survey based on hypothetical situations that these patients may encounter, while taking into account the potential risk of developing severe COVID-19 infection. RESULTS: 60% of the experts had the possibility of monitoring their patients by telemedicine. Most neurologists postpone magnetic resonance. Laboratory blood tests delay is associated with the type of treatment. Platform therapies, dimethyl-fumarate and natalizumab are considered safe options to initiate in naive patients. CONCLUSION: decision-making about MS and NMOSD patients has become even more complex in order to adapt to the COVID-19 pandemic. Risks and benefits should be taken into consideration throughout the patient follow-up.
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COVID-19/complicaciones , Toma de Decisiones Clínicas , Esclerosis Múltiple/diagnóstico , Esclerosis Múltiple/terapia , Neuromielitis Óptica/diagnóstico , Neuromielitis Óptica/terapia , Adulto , Estudios Transversales , Femenino , Personal de Salud , Humanos , América Latina , Masculino , Persona de Mediana Edad , Esclerosis Múltiple/complicaciones , Neuromielitis Óptica/complicaciones , Encuestas y CuestionariosRESUMEN
Proprotein convertase subtilisin-like/kexin type 9 (PCSK9) is a key regulator of plasma LDL-cholesterol (LDL-C) and a clinically validated target for the treatment of hypercholesterolemia and coronary artery disease. In this paper, we describe a series of novel cyclic peptides derived from an mRNA display screen which inhibit the protein-protein interaction between PCSK9 and LDLR. Using a structure-based drug design approach, we were able to modify our original screening lead 2 to optimize the potency and metabolic stability and minimize the molecular weight to provide novel bicyclic next-generation PCSK9 inhibitor peptides such as 78. These next-generation peptides serve as a critical foundation for continued exploration of potential oral, once-a-day PCSK9 therapeutics for the treatment of cardiovascular disease.
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Diseño de Fármacos , Inhibidores Enzimáticos/metabolismo , Inhibidores de PCSK9 , Proproteína Convertasa 9/metabolismo , ARN Mensajero/metabolismo , Animales , Células Cultivadas , Cristalografía por Rayos X/métodos , Inhibidores Enzimáticos/química , Femenino , Humanos , Macaca fascicularis , Masculino , Ratones , Ratones Endogámicos C57BL , Proproteína Convertasa 9/química , Estructura Secundaria de Proteína , Estructura Terciaria de Proteína , ARN Mensajero/química , Ratas , Ratas Wistar , Relación Estructura-ActividadRESUMEN
The development of a sequence-general nucleic acid copying system is an essential step in the assembly of a synthetic protocell, an autonomously replicating spatially localized chemical system capable of spontaneous Darwinian evolution. Previously described nonenzymatic template-copying experiments have validated the concept of nonenzymatic replication, but have not yet achieved robust, sequence-general polynucleotide replication. The 5'-phosphorimidazolides of the 2'-amino-2',3'-dideoxyribonucleotides are attractive as potential monomers for such a system because they polymerize by forming 2'-->5' linkages, which are favored in nonenzymatic polymerization reactions using similarly activated ribonucleotides on RNA templates. Furthermore, the 5'-activated 2'-amino nucleotides do not cyclize. We recently described the rapid and efficient nonenzymatic copying of a DNA homopolymer template (dC(15)) encapsulated within fatty acid vesicles using 2'-amino-2',3'-dideoxyguanosine-5'-phosphorimidazolide as the activated monomer. However, to realize a true Darwinian system, the template-copying chemistry must be able to copy most sequences and their complements to allow for the transmission of information from generation to generation. Here, we describe the copying of a series of nucleic acid templates using 2'-amino-2',3'-dideoxynucleotide-5'-phosphorimidazolides. Polymerization reactions proceed rapidly to completion on short homopolymer RNA and LNA templates, which favor an A-type duplex geometry. We show that more efficiently copied sequences are generated by replacing the adenine nucleobase with diaminopurine, and uracil with C5-(1-propynyl)uracil. Finally, we explore the copying of longer, mixed-sequence RNA templates to assess the sequence-general copying ability of 2'-amino-2',3'-dideoxynucleoside-5'-phosphorimidazolides. Our results are a significant step forward in the realization of a self-replicating genetic polymer compatible with protocell template copying and suggest that N2'-->P5'-phosphoramidate DNA may have the potential to function as a self-replicating system.