RESUMEN
How does a plant detect the changing seasons and make important developmental decisions accordingly? How do they incorporate daylength information into their routine physiological processes? Photoperiodism, or the capacity to measure the daylength, is a crucial aspect of plant development that helps plants determine the best time of the year to make vital decisions, such as flowering. The protein CONSTANS (CO) constitutes the central regulator of this sensing mechanism, not only activating florigen production in the leaves but also participating in many physiological aspects in which seasonality is important. Recent discoveries place CO in the center of a gene network that can determine the length of the day and confer seasonal input to aspects of plant development and physiology as important as senescence, seed size, or circadian rhythms. In this review, we discuss the importance of CO protein structure, function, and evolutionary mechanisms that embryophytes have developed to incorporate annual information into their physiology.
Asunto(s)
Regulación de la Expresión Génica de las Plantas , Fotoperiodo , Proteínas de Plantas , Factores de Transcripción , Ritmo Circadiano/fisiología , Ritmo Circadiano/genética , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Flores/genética , Flores/fisiología , Fenómenos Fisiológicos de las Plantas , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estaciones del Año , Factores de Transcripción/metabolismo , Factores de Transcripción/genéticaRESUMEN
Hypoxia exerts profound effects on cell physiology, but its effect on colonic uptake of the microbiota-generated forms of vitamin B1 (i.e., thiamin pyrophosphate [TPP] and free thiamine) has not been described. Here, we used human colonic epithelial NCM460 cells and human differentiated colonoid monolayers as in vitro and ex vivo models, respectively, and were subjected to either chamber (1% O2, 5% CO2, and 94% N2) or chemically (desferrioxamine; 250 µM)-induced hypoxia followed by determination of different physiological-molecular parameters. We showed that hypoxia causes significant inhibition in TPP and free thiamin uptake by colonic NCM460 cells and colonoid monolayers; it also caused a significant reduction in the expression of TPP (SLC44A4) and free thiamin (SLC19A2 and SLC19A3) transporters and in activity of their gene promoters. Furthermore, hypoxia caused a significant induction in levels of hypoxia-inducible transcription factor (HIF)-1α but not HIF-2α. Knocking down HIF-1α using gene-specific siRNAs in NCM460 cells maintained under hypoxic conditions, on the other hand, led to a significant reversal in the inhibitory effect of hypoxia on TPP and free thiamin uptake as well as on the expression of their transporters. Finally, a marked reduction in level of expression of the nuclear factors cAMP responsive element-binding protein 1 and gut-enriched Krüppel-like factor 4 (required for activity of SLC44A4 and SLC19A2 promoters, respectively) was observed under hypoxic conditions. In summary, hypoxia causes severe inhibition in colonic TPP and free thiamin uptake that is mediated at least in part via HIF-1α-mediated transcriptional mechanisms affecting their respective transporters.
Asunto(s)
Subunidad alfa del Factor 1 Inducible por Hipoxia , Microbiota , Tiamina , Transporte Biológico , Hipoxia de la Célula/fisiología , Humanos , Hipoxia/metabolismo , Hipoxia/microbiología , Subunidad alfa del Factor 1 Inducible por Hipoxia/genética , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Proteínas de Transporte de Membrana/metabolismo , Tiamina/metabolismo , Tiamina Pirofosfato/metabolismoRESUMEN
Flowering time is a key process in plant development. Photoperiodic signals play a crucial role in the floral transition in Arabidopsis thaliana, and the protein CONSTANS (CO) has a central regulatory function that is tightly regulated at the transcriptional and post-translational levels. The stability of CO protein depends on a light-driven proteasome process that optimizes its accumulation in the evening to promote the production of the florigen FLOWERING LOCUS T (FT) and induce seasonal flowering. To further investigate the post-translational regulation of CO protein we have dissected its interactome network employing in vivo and in vitro assays and molecular genetics approaches. The immunophilin FKBP12 has been identified in Arabidopsis as a CO interactor that regulates its accumulation and activity. FKBP12 and CO interact through the CCT domain, affecting the stability and function of CO. fkbp12 insertion mutants show a delay in flowering time, while FKBP12 overexpression accelerates flowering, and these phenotypes can be directly related to a change in accumulation of FT protein. The interaction is conserved between the Chlamydomonas algal orthologs CrCO-CrFKBP12, revealing an ancient regulatory step in photoperiod regulation of plant development.
Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/crecimiento & desarrollo , Proteínas de Unión al ADN/metabolismo , Flores/crecimiento & desarrollo , Isomerasa de Peptidilprolil/metabolismo , Factores de Transcripción/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Chlamydomonas reinhardtii/genética , Secuencia Conservada , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/fisiología , Flores/genética , Flores/metabolismo , Regulación de la Expresión Génica de las Plantas , Isomerasa de Peptidilprolil/genética , Fotoperiodo , Dominios y Motivos de Interacción de Proteínas , Reacción en Cadena en Tiempo Real de la Polimerasa , Factores de Transcripción/genética , Factores de Transcripción/fisiología , Técnicas del Sistema de Dos HíbridosRESUMEN
The water-soluble vitamin B1 is essential for normal human health and physiology. In its main biologically active form, i.e., thiamin pyrophosphate (TPP), the vitamin plays many critical roles in cell metabolism; thus, its deficiency leads to a variety of adverse effects. Humans/mammals obtain vitamin B1 from two exogenous sources: diet and gut microbiota. Considerable amount of the microbiota-generated vitamin B1 exists in the form of TPP, and colonocytes can efficiently absorb this TPP via a high-affinity and specific carrier-mediated mechanism that involves the recently cloned colonic TPP transporter (cTPPT; product of SLC44A4 gene). There is nothing currently known about colonic uptake of TPP during early stages of life and whether the process undergoes developmental regulation. We addressed this issue using the mouse as animal model. Our results showed that colonic uptake of TPP undergoes developmental upregulation as the animal moves from the suckling period to weanling and adulthood. This upregulation in uptake was found to be associated with a parallel induction in level of expression of the cTPPT protein, mRNA, and heterogeneous nuclear RNA, suggesting possible involvement of transcriptional mechanism(s). We also found a parallel upregulation in the level of expression of the two nuclear factors that drive activity of the SLC44A4 promoter (i.e., CREB-1 and Elf-3) with maturation. These results demonstrate, for the first time, to our knowledge, that colonic TPP uptake process and cTPPT expression are developmentally upregulated and that this upregulation is likely driven via transcriptional mechanism(s).NEW & NOTEWORTHY The colonic carrier-mediated uptake process of the microbiota-generated and phosphorylated form of vitamin B1, i.e., thiamin pyrophosphate, undergoes ontogenic changes that parallel the development of the gut microbiota (and their ability to generate vitamins) during early stages of life.
Asunto(s)
Colon/metabolismo , Microbioma Gastrointestinal/fisiología , Proteínas de Transporte de Membrana/metabolismo , Tiamina Pirofosfato/metabolismo , Animales , Dieta , Femenino , Masculino , RatonesRESUMEN
The present work presents the results obtained with a stainless steel (SS) voltammetric sensor to detect variations in humidity (H2O) and oxygen (O2) availability in concretes. First, studies in solution were run by preparing several solutions to represent the different conditions that can be found in concrete pores. Second, the sensor's response was studied by varying O2 availability by argon or synthetic air bubbling. Then concrete conditions with different degrees of carbonation were simulated using solutions with a pH between 13 and 8.45. After characterization in solution, a study by means of concrete samples with several water/cement ratios (0.6, 0.5 and 0.4) was performed, in which sensors were embedded and studied under different O2 and H2O saturation conditions. The obtained results revealed that with the voltagram, it is possible to evaluate O2 availability variation from the slopes of the lines identified logarithmically in the voltagram for the obtained cathodic sweeping. All the results obtained with the sensor were correlated/validated by standard assays to characterize porosity in hardened concretes.
RESUMEN
Flowering is a crucial process that demands substantial resources. Carbon metabolism must be coordinated with development through a control mechanism that optimizes fitness for any physiological need and growth stage of the plant. However, how sugar allocation is controlled during the floral transition is unknown. Recently, the role of a CONSTANS (CO) ortholog (Cr-CO) in the control of the photoperiod response in the green alga Chlamydomonas reinhardtii and its influence on starch metabolism was demonstrated. In this work, we show that transitory starch accumulation and glycan composition during the floral transition in Arabidopsis thaliana are regulated by photoperiod. Employing a multidisciplinary approach, we demonstrate a role for CO in regulating the level and timing of expression of the GRANULE BOUND STARCH SYNTHASE (GBSS) gene. Furthermore, we provide a detailed characterization of a GBSS mutant involved in transitory starch synthesis and analyze its flowering time phenotype in relation to its altered capacity to synthesize amylose and to modify the plant free sugar content. Photoperiod modification of starch homeostasis by CO may be crucial for increasing the sugar mobilization demanded by the floral transition. This finding contributes to our understanding of the flowering process.
Asunto(s)
Arabidopsis/fisiología , Carbono/metabolismo , Flores/fisiología , Fotoperiodo , Arabidopsis/genética , Arabidopsis/crecimiento & desarrollo , Proteínas de Arabidopsis/metabolismo , Regulación de la Expresión Génica de las Plantas , Ontología de Genes , Modelos Biológicos , Mutación/genética , Plantas Modificadas Genéticamente , ARN Mensajero/genética , ARN Mensajero/metabolismo , Solubilidad , Almidón/metabolismoRESUMEN
BACKGROUND: Chlamydomonas reinhardtii is the model organism that serves as a reference for studies in algal genomics and physiology. It is of special interest in the study of the evolution of regulatory pathways from algae to higher plants. Additionally, it has recently gained attention as a potential source for bio-fuel and bio-hydrogen production. The genome of Chlamydomonas is available, facilitating the analysis of its transcriptome by RNA-seq data. This has produced a massive amount of data that remains fragmented making necessary the application of integrative approaches based on molecular systems biology. RESULTS: We constructed a gene co-expression network based on RNA-seq data and developed a web-based tool, ChlamyNET, for the exploration of the Chlamydomonas transcriptome. ChlamyNET exhibits a scale-free and small world topology. Applying clustering techniques, we identified nine gene clusters that capture the structure of the transcriptome under the analyzed conditions. One of the most central clusters was shown to be involved in carbon/nitrogen metabolism and signalling, whereas one of the most peripheral clusters was involved in DNA replication and cell cycle regulation. The transcription factors and regulators in the Chlamydomonas genome have been identified in ChlamyNET. The biological processes potentially regulated by them as well as their putative transcription factor binding sites were determined. The putative light regulated transcription factors and regulators in the Chlamydomonas genome were analyzed in order to provide a case study on the use of ChlamyNET. Finally, we used an independent data set to cross-validate the predictive power of ChlamyNET. CONCLUSIONS: The topological properties of ChlamyNET suggest that the Chlamydomonas transcriptome posseses important characteristics related to error tolerance, vulnerability and information propagation. The central part of ChlamyNET constitutes the core of the transcriptome where most authoritative hub genes are located interconnecting key biological processes such as light response with carbon and nitrogen metabolism. Our study reveals that key elements in the regulation of carbon and nitrogen metabolism, light response and cell cycle identified in higher plants were already established in Chlamydomonas. These conserved elements are not only limited to transcription factors, regulators and their targets, but also include the cis-regulatory elements recognized by them.
Asunto(s)
Chlamydomonas reinhardtii/genética , Redes Reguladoras de Genes , Transcriptoma , Análisis por Conglomerados , ADN de Algas/genética , Familia de Multigenes , Secuencias Reguladoras de Ácidos Nucleicos , Análisis de Secuencia de ARN , Programas Informáticos , Factores de Transcripción/genéticaRESUMEN
The response to daylength is a crucial process that evolved very early in plant evolution, entitling the early green eukaryote to predict seasonal variability and attune its physiological responses to the environment. The photoperiod responses evolved into the complex signaling pathways that govern the angiosperm floral transition today. The Chlamydomonas reinhardtii DNA-Binding with One Finger (CrDOF) gene controls transcription in a photoperiod-dependent manner, and its misexpression influences algal growth and viability. In short days, CrDOF enhances CrCO expression, a homolog of plant CONSTANS (CO), by direct binding to its promoter, while it reduces the expression of cell division genes in long days independently of CrCO. In Arabidopsis (Arabidopsis thaliana), transgenic plants overexpressing CrDOF show floral delay and reduced expression of the photoperiodic genes CO and FLOWERING LOCUS T. The conservation of the DOF-CO module during plant evolution could be an important clue to understanding diversification by the inheritance of conserved gene toolkits in key developmental programs.
Asunto(s)
Chlamydomonas reinhardtii/metabolismo , Secuencia Conservada , Evolución Molecular , Fotoperiodo , Proteínas de Plantas/metabolismo , Transducción de Señal , Arabidopsis/genética , Arabidopsis/fisiología , Proteínas de Arabidopsis/metabolismo , Ciclo Celular , Chlamydomonas reinhardtii/genética , Chlamydomonas reinhardtii/crecimiento & desarrollo , Ritmo Circadiano , Flores/fisiología , Perfilación de la Expresión Génica , Regulación de la Expresión Génica de las Plantas , Modelos Biológicos , Filogenia , Proteínas de Plantas/genética , Plantas Modificadas Genéticamente , Unión Proteica , Estructura Terciaria de Proteína , Factores de Transcripción/metabolismoRESUMEN
BACKGROUND: The aim of this study was to analyze the clinicopathologic features of melanoma in México as the demographics of melanoma are not well known in Mexican and Latin American people. MATERIALS AND METHODS: A total of 1219 patients with cutaneous melanoma were analyzed through a retrospective database collected from a cancer referral institute, and the results were compared with developed countries. RESULTS: Median age was 57 years, and 713 (58.5 %) were females. The most common melanoma subtype was acral lentiginous melanoma (ALM), which was observed in 538 (44.1 %) patients. Median Breslow thickness was 5.2 mm. Among 837 patients with complete data, the 5-year disease-specific survival (DSS) was 52.3 %. Factors associated with worse DSS on univariate analysis were Breslow thickness (p < 0.001), recurrence (p < 0.001), ulceration (p < 0.001), positive margin (p < 0.001), ALM (p = 0.001), and male sex (p = 0.001). Multivariate analysis demonstrated Breslow thickness [hazard ratio (HR) 1.45, 95 % confidence interval (CI) 1.27-1.65; p < 0.001], positive margin (HR 1.25, 95 % CI 1.03-1.57; p = 0.018), recurrence (HR 9.56, 95 % CI 6.89-9.87; p = 0.002), ALM (HR 8.07, 95 % CI 6.77-8.95; p = 0.004), and male sex (HR 1.33, 95 % CI 1.06-1.68; p = 0.013) as independent risk factors for DSS. CONCLUSION: Our patients had worse prognosis compared with data from the US Surveillance, Epidemiology, and End Results database. We found male sex and ALM as independent risk factors for worse survival, in addition to known risk factors.
Asunto(s)
Peca Melanótica de Hutchinson/patología , Recurrencia Local de Neoplasia , Neoplasias Cutáneas/patología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Extremidades , Femenino , Humanos , Peca Melanótica de Hutchinson/epidemiología , Peca Melanótica de Hutchinson/mortalidad , Incidencia , Masculino , México/epidemiología , Persona de Mediana Edad , Recurrencia Local de Neoplasia/mortalidad , Estadificación de Neoplasias , Neoplasia Residual , Estudios Retrospectivos , Factores de Riesgo , Factores Sexuales , Neoplasias Cutáneas/epidemiología , Neoplasias Cutáneas/mortalidad , Tasa de Supervivencia , Carga Tumoral , Adulto JovenRESUMEN
BACKGROUND AND OBJECTIVES: We aimed to determine the prognostic value of the mesorectum quality assessed in a two-grade system compared with a classic system. METHODS: Consecutive patients undergoing surgery for rectal cancer were included (n = 103). Mesorectum was assessed into three grades (classic system: complete, nearly complete, incomplete) and compared with a two-grade system (adequate, inadequate). RESULTS: Mesorectum was complete in 62 (60.25%) patients, nearly complete in 21, and incomplete in 20. Reassessment showed adequate mesorectum in 83 (80.5%) patients and inadequate in 20. A R0 resection was achieved in 90.4% of adequate mesorectum and in 65% of inadequate mesorectum (P = 0.006). Recurrence was present in 18% of adequate mesorectum patients as compared with 50% of inadequate mesorectum (P = 0.003). The classic system failed to accurately predict the 5-year survival rate between complete (78.9%) and nearly complete (86.2%) categories (P = 0.235); whereas a two grading system showed a 5-year survival rate of 80.8% for adequate versus 39.3% for inadequate (P = 0.034). CONCLUSION: High recurrence occurred in inadecuate mesorectum patients and was correlated with R1/R2 resections, positive margins, and decreased survival. We propose a simplified classification of mesorectum that correlates with survival and overall recurrence.
Asunto(s)
Neoplasias del Recto/mortalidad , Neoplasias del Recto/patología , Adulto , Anciano , Anciano de 80 o más Años , Estudios de Cohortes , Supervivencia sin Enfermedad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Clasificación del Tumor , Invasividad Neoplásica , Estadificación de Neoplasias , Neoplasia Residual , Valor Predictivo de las Pruebas , Neoplasias del Recto/cirugía , Tasa de Supervivencia , Resultado del Tratamiento , Adulto JovenRESUMEN
Plants are sessile organisms that have acquired highly plastic developmental strategies to adapt to the environment. Among these processes, the floral transition is essential to ensure reproductive success and is finely regulated by several internal and external genetic networks. The photoperiodic pathway, which controls plant response to day length, is one of the most important pathways controlling flowering. In Arabidopsis photoperiodic flowering, CONSTANS (CO) is the central gene activating the expression of the florigen FLOWERING LOCUS T (FT) in the leaves at the end of a long day. The circadian clock strongly regulates CO expression. However, to date, no evidence has been reported regarding a feedback loop from the photoperiod pathway back to the circadian clock. Using transcriptional networks, we have identified relevant network motifs regulating the interplay between the circadian clock and the photoperiod pathway. Gene expression, chromatin immunoprecipitation experiments, and phenotypic analysis allowed us to elucidate the role of CO over the circadian clock. Plants with altered CO expression showed a different internal clock period, measured by daily leaf rhythmic movements. We showed that CO upregulates the expression of key genes related to the circadian clock, such as CCA1, LHY, PRR5, and GI, at the end of a long day by binding to specific sites on their promoters. Moreover, a high number of PRR5-repressed target genes are upregulated by CO, and this could explain the phase transition promoted by CO. The CO-PRR5 complex interacts with the bZIP transcription factor HY5 and helps to localize the complex in the promoters of clock genes. Taken together, our results indicate that there may be a feedback loop in which CO communicates back to the circadian clock, providing seasonal information to the circadian system.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Relojes Circadianos , Proteínas de Unión al ADN , Regulación de la Expresión Génica de las Plantas , Fotoperiodo , Factores de Transcripción , Arabidopsis/genética , Arabidopsis/fisiología , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Relojes Circadianos/genética , Factores de Transcripción/metabolismo , Factores de Transcripción/genética , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Flores/genética , Flores/fisiologíaRESUMEN
Traditional medicine in Latin America and mainly in Mexico represents an essential alternative for treating different diseases. The use of plants as medicine is the product of a rich cultural tradition of the indigenous peoples, in which a great variety of species are used for the treatment of gastrointestinal, respiratory, and mental diseases and some other sicknesses; the therapeutic efficacy that they possess is due to the properties that derive from the active ingredients of plants principally antioxidants, such as phenolic compounds, flavonoids, terpenes, and tannins. An antioxidant is a substance that, at low concentrations, delays or prevents substrate oxidation through the exchange of electrons. Different methods are used to determine the antioxidant activity and the most commonly used are described in the review. Cancer is a disease in which some cells multiply uncontrollably and spread to other parts of the body, a process known as metastasis. These cells can lead to the formation of tumors, which are lumps of tissue that can be cancerous (malignant) or noncancerous (benign). Generally, the treatment of this disease consists of surgery, radiotherapy, or chemotherapy, which have side effects that decrease the quality of life of patients, so new treatments, focusing on natural resources such as plants, can be developed. This review aims to gather scientific evidence on the antioxidant compounds present in plants used in traditional Mexican medicine, specifically as antitumor treatment in the most common cancer types worldwide (e.g., breast, liver, and colorectal cancer).
RESUMEN
BACKGROUND: Tumor deposits (TDs) are associated with adverse prognostic factors and decreased survival in colon cancer. However, there is no information of their survival impact in rectal cancer with neoadjuvant chemoradiotherapy (n-CRT). METHODS: Retrospective study in 223 patients with rectal cancer with n-CRT. A survival analysis of factors associated with decreased overall survival (OS) including TDs was performed. RESULTS: From 223 patients, 131 (58.7%) were men, mean age 59.8 (± 13.06) years, and 42 (18.8%) of them revealed TDs. Survival analysis of TDs showed no association with mortality. Factors associated with decreased 5-year OS were the histologic grade (p = 0.42), perineural invasion (p = 0.001), and mesorectal quality (p = 0.067). Perineural invasion (HR = 2.335, 95% CI = 1.198-4.552) remained as independent factor in the multivariate analysis. CONCLUSIONS: TDs were not associated with mortality in rectal cancer patients treated with n-CRT. Factors associated with decreased survival were inadequate mesorectal quality and perineural invasion.
Asunto(s)
Adenocarcinoma , Neoplasias del Recto , Masculino , Humanos , Persona de Mediana Edad , Femenino , Terapia Neoadyuvante , Estudios Retrospectivos , Extensión Extranodal/patología , Estadificación de Neoplasias , Supervivencia sin Enfermedad , Adenocarcinoma/patología , Pronóstico , Neoplasias del Recto/cirugía , Neoplasias del Recto/tratamiento farmacológico , Quimioradioterapia , Quimioradioterapia AdyuvanteRESUMEN
Gold nanoparticles (AuNPs) are promising nanomaterials exhibiting anti-cancer effects. Green AuNPs synthesis using plant extracts can be used to achieve stable and beneficial nanoparticles due to their content of bioactive compounds. This research aimed to synthesize and evaluate the antiproliferative and caspase-3 activity induction of green AuNPs synthesized with common mullein (V. thapsus) flowers (AuNPsME) and castor bean (R. communis) leaves (AuNPsCE) ethanolic extracts in human HT29 and SW480 colorectal cancer cells. Their effect was compared with chemically synthesized AuNPs (AuNPsCS). The extracts mainly contained p-coumaric acid (71.88-79.93 µg/g), ferulic acid (19.07-310.71 µg/g), and rutin (8.14-13.31 µg/g). The obtained nanoparticles presented typical FT-IR bands confirming the inclusion of polyphenols from V. thapsus and R. communis and spherical/quasi-spherical morphologies with diameters in the 20.06-37.14 nm range. The nanoparticles (20-200 µg/mL) showed antiproliferative effects in both cell lines, with AuNPsCE being the most potent (IC50 HT29: 110.10 and IC50SW480: 64.57 µg/mL). The AuNPsCS showed the lowest intracellular reactive oxygen species (ROS) generation in SW480 cells. All treatments induced caspase 3/7 activity to a similar or greater extent than 30 mM H2O2-treated cells. Results indicated the suitability of V. thapsus and R. communis extracts to synthesize AuNPs, displaying a stronger antiproliferative effect than AuNPsCS.
RESUMEN
The SiO2 particles system is one of the most common ways to protect colloidal metal systems, such as gold nanoparticles, from aggregation and activity loss due to their high chemical stability and low reactivity. In this study, silica green gold nanoparticles (AuNPs synthesized with mullein extract) were fabricated using two different sol-gel methods. The nanoparticles were characterized by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Fourier Transformed Infrared (FTIR), and the antibacterial activity against pathogens (Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Salmonella enterica). Synthesis-1 nanoparticles had a kidney-shaped form and uniform distribution, while synthesis-2 nanoparticles had a spherical and non-uniform form. Characterization showed that temperature is an important factor in the distribution of AuNPs in silica; a decrease allowed the formation of Janus-type, and an increase showed a higher concentration of gold in energy-dispersive spectroscopy (EDS) analysis. Overall, similar bands of the two synthesis silica nanoparticles were observed in FTIR, while XRD spectra showed differences in the preferential growth in AuNPs depending on the synthesis. Higher antibacterial activity was observed against S. aureus, which was followed by L. monocytogenes. No differences were observed in the antibacterial activity between the two different sol-gel methods.
RESUMEN
Nanocomposite engineering of biosensors, biomaterials, and flexible electronics demand a highly tunable synthesis of precursor materials to achieve enhanced or desired properties. However, this process remains limited due to the need for proper synthesis-property strategies. Herein, we report on the ability to synthesize chitosan-gold nanocomposite thin films (CS/AuNP) with tunable properties by chemically reducing HAuCl4 in chitosan solutions and different HAuCl4/sodium citrate molar relationships. The structure, electrical, and relaxation properties of nanocomposites have been investigated as a function of HAuCl4/sodium citrate molar relation. It was shown that gold particle size, conductivity, Vogel temperature (glass transition), and water content strongly depend upon HAuCl4/sodium citrate relationships. Two relaxation processes have been observed in nanocomposites; the α-relaxation process, related to a glass transition in wet CS/AuNP films, and the σ-relaxation related to the local diffusion process of ions in a disordered system. The ability to fine-tune both α- and σ-relaxations may be exploited in the proper design of functional materials for biosensors, biomaterials, and flexible electronics applications.
RESUMEN
It is widely considered that ADP-glucose pyrophosphorylase (AGP) is the sole source of ADP-glucose linked to bacterial glycogen and plant starch biosynthesis. Genetic evidence that bacterial glycogen biosynthesis occurs solely by the AGP pathway has been obtained with glgCâ» AGP mutants. However, recent studies have shown that (i) these mutants can accumulate high levels of ADP-glucose and glycogen, and (ii) there are sources other than GlgC, of ADP-glucose linked to glycogen biosynthesis. In Arabidopsis, evidence showing that starch biosynthesis occurs solely by the AGP pathway has been obtained with the starchless adg1-1 and aps1 AGP mutants. However, mounting evidence has been compiled previewing the occurrence of more than one important ADP-glucose source in plants. In attempting to solve this 20-year-old controversy, in this work we carried out a judicious characterization of both adg1-1 and aps1. Both mutants accumulated wild-type (WT) ADP-glucose and approximately 2% of WT starch, as further confirmed by confocal fluorescence microscopic observation of iodine-stained leaves and of leaves expressing granule-bound starch synthase fused with GFP. Introduction of the sex1 mutation affecting starch breakdown into adg1-1 and aps1 increased the starch content to 8-10% of the WT starch. Furthermore, aps1 leaves exposed to microbial volatiles for 10 h accumulated approximately 60% of the WT starch. aps1 plants expressing the bacterial ADP-glucose hydrolase EcASPP in the plastid accumulated normal ADP-glucose and reduced starch when compared with aps1 plants, whereas aps1 plants expressing EcASPP in the cytosol showed reduced ADP-glucose and starch. Moreover, aps1 plants expressing bacterial AGP in the plastid accumulated WT starch and ADP-glucose. The overall data show that (i) there occur important source(s), other than AGP, of ADP-glucose linked to starch biosynthesis, and (ii) AGP is a major determinant of starch accumulation but not of intracellular ADP-glucose content in Arabidopsis.
Asunto(s)
Adenosina Difosfato Glucosa/biosíntesis , Proteínas de Arabidopsis/metabolismo , Arabidopsis/enzimología , Glucosa-1-Fosfato Adenililtransferasa/metabolismo , Almidón/biosíntesis , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Glucosa-1-Fosfato Adenililtransferasa/genética , Mutación , Hojas de la Planta/metabolismo , Plantas Modificadas Genéticamente/enzimología , Plantas Modificadas Genéticamente/genética , Almidón Sintasa/metabolismoRESUMEN
The aim of this experimental work was to study the porous structure of Ultra-High-Performance Fibre-Reinforced Concretes (UH) made with different fibre volume contents (0%, 1%, 2%) under several curing conditions (laboratory environment, 20 °C, 60 °C, 90 °C), comparing the results with those recorded for ordinary, high strength and very high strength concretes. Scanning electron microscopy, mercury intrusion porosimetry, thermogravimetry, water absorption and oxygen permeability tests were carried out. The results showed a low portlandite content in UH (in the order of 75% lower than in concrete C50) and a low degree of hydration, but they rise with curing temperature. These concretes have a very fine porous structure, with a high concentration of pores on the nanoscale level, below 0.05 µm. Their porosity accessible to water is consequently around 7-fold lower than in conventional (C30), 6-fold lower than in high-strength (C50) and 4-fold lower than in very high-strength (C90) concretes. Their oxygen permeability is at least one order of magnitude lower than in C90, two orders of magnitude lower than in C50 and three orders of magnitude lower than in C30. The percentage of added steel fibre does not affect the UH porous structure.
RESUMEN
The energy sector is one of the fields of interest for different nations around the world. Due to the current fossil fuel crisis, the scientific community develops new energy-saving experiences to address this concern. Buildings are one of the elements of higher energy consumption, so the generation of knowledge and technological development may offer solutions to this energy demand, which are more than welcome. Phase change materials (PCMs) included in building elements such as wall panels, blocks, panels or coatings, for heating and cooling applications have been shown, when heating, to increase the heat storage capacity by absorbing heat as latent heat. Therefore, the use of latent heat storage systems using phase change materials (PCMs) has been investigated within the last two decades. In the present review, the macro and micro encapsulation methods for construction materials are reviewed, the former being the most viable method of inclusion of PCMs in construction elements. In addition, based on the analysis of the existing papers on the encapsulation process of PCMs, the importance to pay more attention to the bio-based PCMs is shown, since more research is needed to process such PCMs. To determine its thermophysical and mechanical behavior at the micro and macro levels, in order to see the feasibility of substituting petroleum-based PCMs with a more environmentally friendly bio-based one, a section devoted to the excellent PCM with lightweight aggregate (PCM-LWA concrete) is presented due to the lack of description given in other reviews.
RESUMEN
Inflammation has been implicated as an etiological factor in different human cancers. Allelic variations in the genes implicated in inflammation are candidates as genetic determinants or markers of renal carcinoma risk. The present stud investigates whether polymorphisms of the genes that give rise to increases in the levels of proinflammatory cytokines and chemokines are associated with an increased risk of renal carcinoma. To this effect, a number of case-control studies were designed to assess the correlation between renal carcinoma and polymorphisms IL10-1082 A/G (rs 1800896), IL10-592 A/C (rs 1800872), IL10-819 C/T (rs 1800871), IL10-1082 A/G, IL4-590 C/T (rs 2243250), TNF-A-308 A/G (rs 1800629), RANTES-403 G/A (rs 2107538), IL1-A-889 C/T (rs 1800587), MCP-1 2518 G/A (rs 1024611), CTLA-4/+49 A/G (rs 231775) and CTLA-4 CT60 A/G (rs 3087243) in 127 renal carcinoma patients and in 176 healthy subjects. The results obtained in relation to cytokine polymorphism IL-10-1082 A/G indicate that AG heterozygosity status is the principal risk factor in relation to locally advanced or metastatic tumor stage and renal carcinoma. In the case of the molecule CTLA4, the results obtained in renal cancer reveal an association between the polymorphisms of the CTLA-4 gene and an increased risk of developing renal cell carcinoma. A high genotypic frequency of polymorphisms CTLA4/CT60-AA and CTLA4/A49G-AA is observed in patients with renal cell carcinoma versus the controls. An association has been established between polymorphism CTLA4/CT60 and tumor grade in patients with renal cell carcinoma. Logistic regression analysis has confirmed these data, demonstrating a high frequency of the AA genotype in patients with high-grade tumors. The results obtained support the hypothesis that different genetic factors implicated in the regulation of adaptive immune responses, stromal cell composition and local cytokine production levels may be crucial elements in the modification of the clinicopathological parameters of renal carcinoma.