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1.
ACS Nano ; 18(26): 16622-16631, 2024 Jul 02.
Artículo en Inglés | MEDLINE | ID: mdl-38904174

RESUMEN

Atomically precise graphene nanoribbons (GNRs) have a wide range of electronic properties that depend sensitively on their chemical structure. Several types of GNRs have been synthesized on metal surfaces through selective surface-catalyzed reactions. The resulting GNRs are adsorbed on the metal surface, which may lead to hybridization between the GNR orbitals and those of the substrate. This makes investigation of the intrinsic electronic properties of GNRs more difficult and also rules out capacitive gating. Here, we demonstrate the formation of a dielectric gold chloride adlayer that can intercalate underneath GNRs on the Au(111) surface. The intercalated gold chloride adlayer electronically decouples the GNRs from the metal and leads to a substantial hole-doping of the GNRs. Our results introduce an easily accessible tool in the in situ characterization of GNRs grown on Au(111) that allows for exploration of their electronic properties in a heavily hole-doped regime.

2.
Acta Crystallogr E Crystallogr Commun ; 80(Pt 4): 388-391, 2024 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-38584735

RESUMEN

The title compound, C8H7NO2, crystallizes as prismatic colourless crystals in space group P , with one mol-ecule in the asymmetric unit. The pyridine ring is fused to acrylic acid, forming an almost planar structure with an E-configuration about the double bond with a torsion angle of -6.1 (2)°. In the crystal, strong O-H⋯N inter-actions link the mol-ecules, forming chains along the [101] direction. Weak C-H⋯O inter-actions link adjacent chains along the [100] direction, generating an R 2 2(14) homosynthon. Finally, π-π stacking inter-actions lead to the formation of the three-dimensional structure. The supra-molecular analysis was supported by Hirshfeld surface and two-dimensional fingerprint plot analysis, indicating that the most abundant contacts are associated with H⋯H, O⋯H/H⋯O, N⋯H/H⋯N and C⋯H/H⋯C inter-actions.

3.
ACS Chem Biol ; 19(4): 875-885, 2024 04 19.
Artículo en Inglés | MEDLINE | ID: mdl-38483263

RESUMEN

It is well established that oxaliplatin, one of the three Pt(II) anticancer drugs approved worldwide, and phenanthriplatin, an important preclinical monofunctional Pt(II) anticancer drug, possess a different mode of action from that of cisplatin and carboplatin, namely, the induction of nucleolar stress. The exact mechanisms that lead to Pt-induced nucleolar stress are, however, still poorly understood. As such, studies aimed at better understanding the biological targets of both oxaliplatin and phenanthriplatin are urgently needed to expand our understanding of Pt-induced nucleolar stress and guide the future design of Pt chemotherapeutics. One approach that has seen great success in the past is the use of Pt-click complexes to study the biological targets of Pt drugs. Herein, we report the synthesis and characterization of the first examples of click-capable phenanthriplatin complexes. Furthermore, through monitoring the relocalization of nucleolar proteins, RNA transcription levels, and DNA damage repair biomarker γH2AX, and by investigating their in vitro cytotoxicity, we show that these complexes successfully mimic the cellular responses observed for phenanthriplatin treatment in the same experiments. The click-capable phenanthriplatin derivatives described here expand the existing library of Pt-click complexes. Significantly they are suitable for studying nucleolar stress mechanisms and further elucidating the biological targets of Pt complexes.


Asunto(s)
Antineoplásicos , Nucléolo Celular , Compuestos Organoplatinos , Fenantridinas , Antineoplásicos/farmacología , Antineoplásicos/metabolismo , Cisplatino/farmacología , Compuestos Organoplatinos/química , Compuestos Organoplatinos/farmacología , Oxaliplatino/farmacología , Fenantridinas/síntesis química , Fenantridinas/química , Fenantridinas/farmacología , Química Clic , Nucléolo Celular/efectos de los fármacos , Nucléolo Celular/metabolismo
4.
Biol Trace Elem Res ; 202(1): 246-257, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-37086356

RESUMEN

This study is based on the premise that the application of chemical synthesis strategies to structurally modify commercial drugs by complexation with biometals is a valid procedure to improve their biological effects. Our purpose is to synthesize a compound with greater efficacy than the original drug, able to enhance its antihypertensive and cardiac pharmacological activity. Herein, the structure of the coordination compound of Zn(II) and the antihypertensive drug olmesartan, [Zn(Olme)(H2O)2] (ZnOlme), is presented. After 8 weeks of treatment in SHR male rats, ZnOlme displayed a better blood pressure-lowering activity compared with olmesartan, with a noticeable effect even in the first weeks of treatment, while ZnCl2 showed similar results than the control. ZnOlme also reduced left ventricle (LV) weight and left ventricle/tibia length ratio (LV/TL), posterior wall thickness (PWT), and intraventricular septum in diastole (IVSd) suggesting its potential to prevent LV hypertrophy. Besides, ZnOlme reduced interstitial fibrosis (contents of collagen types I and III, responsible for giving rigidity and promoting vascular elasticity, respectively). The recovery of heart function was also evidenced by fractional shortening (diastolic left ventricular/systolic left ventricular) diameter determinations. Furthermore, ZnOlme increased the antioxidant capacity and prevented cardiac oxidative stress: it enhanced the reduction of reactive oxygen species generation, exerted a significant decrease in lipid peroxidation and enhanced glutathione contents in heart tissues compared to the control, Zn, and olmesartan treatments. Our results demonstrate that continuous oral administration of ZnOlme causes a better antihypertensive effect and grants enhancement of cardioprotection through antioxidant activity, in combination with hemodynamic improvement.


Asunto(s)
Antihipertensivos , Hipertensión , Ratas , Animales , Masculino , Antihipertensivos/farmacología , Antihipertensivos/uso terapéutico , Hipertensión/tratamiento farmacológico , Ratas Endogámicas SHR , Presión Sanguínea , Hipertrofia Ventricular Izquierda/tratamiento farmacológico , Hipertrofia Ventricular Izquierda/prevención & control , Zinc/farmacología , Zinc/uso terapéutico
5.
RSC Chem Biol ; 4(10): 785-793, 2023 Oct 04.
Artículo en Inglés | MEDLINE | ID: mdl-37799581

RESUMEN

Pt(ii) chemotherapeutic complexes have been used as predominant anticancer drugs for nearly fifty years. Currently there are three FDA-approved chemotherapeutic Pt(ii) complexes: cisplatin, carboplatin, and oxaliplatin. Until recently, it was believed that all three complexes induced cellular apoptosis through the DNA damage response pathway. Studies within the last decade, however, suggest that oxaliplatin may instead induce cell death through a unique nucleolar stress pathway. Pt(ii)-induced nucleolar stress is not well understood and further investigation of this pathway may provide both basic knowledge about nucleolar stress as well as insight for more tunable Pt(ii) chemotherapeutics. Through a previous structure-function analysis, it was determined that nucleolar stress induction is highly sensitive to modifications at the 4-position of the 1,2-diaminocyclohexane (DACH) ring of oxaliplatin. Specifically, more flexible and less rigid substituents (methyl, ethyl, propyl) induce nucleolar stress, while more rigid and bulkier substituents (isopropyl, acetamide) do not. These findings suggest that a click-capable functional group can be installed at the 4-position of the DACH ring while still inducing nucleolar stress. Herein, we report novel click-capable azide-modified oxaliplatin mimics that cause nucleolar stress. Through NPM1 relocalization, fibrillarin redistribution, and γH2AX studies, key differences have been identified between previously studied click-capable cisplatin mimics and these novel click-capable oxaliplatin mimics. These complexes provide new tools to identify cellular targets and localization through post-treatment Cu-catalyzed azide-alkyne cycloaddition and may help to better understand Pt(ii)-induced nucleolar stress. To our knowledge, these are the first reported oxaliplatin mimics to include an azide handle, and cis-[(1R,2R,4S) 4-methylazido-1,2-cyclohexanediamine]dichlorido platinum(ii) is the first azide-functionalized oxaliplatin derivative to induce nucleolar stress.

6.
Anal Chem ; 95(21): 8223-8231, 2023 05 30.
Artículo en Inglés | MEDLINE | ID: mdl-37194568

RESUMEN

Mass spectrometry-based glycome analysis is a viable strategy for the compositional and functional exploration of glycosylation. However, the lack of generic tools for high-throughput and reliable glycan spectral interpretation largely hampers the broad usability of glycomic research. Here, we developed a generic and reliable glycomic tool, GlycoNote, for comprehensive and precise glycome analysis. GlycoNote supports interpretation of tandem-mass spectrometry glycomic data from any sample source, uses a novel target-decoy method with iterative decoy searching for highly reliable result output, and embeds an open-search component analysis mode for heterogeneity analysis of monosaccharides and modifications. We tested GlycoNote on several different large-scale glycomic datasets, including human milk oligosaccharides, N- and O-glycome from human cell lines, plant polysaccharides, and atypical glycans from Caenorhabditis elegans, demonstrating its high capacity for glycome analysis. An application of GlycoNote to the analysis of labeled and derived glycans further demonstrates its broad usability in glycomic studies. By enabling generic characterization of various glycan types and elucidation of component heterogeneity in glycomic samples, the freely available GlycoNote is a promising tool for facilitating glycomics in glycobiology research.


Asunto(s)
Glicómica , Polisacáridos/química , Glicómica/métodos , Humanos , Espectrometría de Masas en Tándem
7.
Nat Mater ; 21(12): 1419-1425, 2022 12.
Artículo en Inglés | MEDLINE | ID: mdl-36229651

RESUMEN

The heat capacity of a material is a fundamental property of great practical importance. For example, in a carbon capture process, the heat required to regenerate a solid sorbent is directly related to the heat capacity of the material. However, for most materials suitable for carbon capture applications, the heat capacity is not known, and thus the standard procedure is to assume the same value for all materials. In this work, we developed a machine learning approach, trained on density functional theory simulations, to accurately predict the heat capacity of these materials, that is, zeolites, metal-organic frameworks and covalent-organic frameworks. The accuracy of our prediction is confirmed with experimental data. Finally, for a temperature swing adsorption process that captures carbon from the flue gas of a coal-fired power plant, we show that for some materials, the heat requirement is reduced by as much as a factor of two using the correct heat capacity.


Asunto(s)
Estructuras Metalorgánicas , Nanoporos , Carbón Mineral , Calor , Centrales Eléctricas , Carbono
8.
Am J Trop Med Hyg ; 107(2): 427-432, 2022 08 17.
Artículo en Inglés | MEDLINE | ID: mdl-35895412

RESUMEN

Eight people with human body louse-borne Bartonella quintana infections were detected among people experiencing homelessness (PEH) in Denver during January-September 2020, prompting a public health investigation and community outreach. Public health officials conducted in-person interviews with PEH to more fully quantify body lice prevalence, transmission risk factors, access to PEH resources, and how the COVID-19 pandemic has affected resource access. Recent body lice exposure was reported by 35% of 153 interview participants. In total, 75% of participants reported reduced access to PEH services, including essential hygiene activities to prevent body lice, during Colorado's COVID-19 stay-at-home orders. Future pandemic planning should consider hygiene resource allocation for PEH populations to prevent emerging and reemerging infections such as B. quintana.


Asunto(s)
Bartonella quintana , COVID-19 , Personas con Mala Vivienda , Infestaciones por Piojos , Pediculus , Fiebre de las Trincheras , Animales , Humanos , Pandemias/prevención & control , Colorado/epidemiología , COVID-19/epidemiología , Higiene
9.
Chembiochem ; 23(14): e202200130, 2022 07 19.
Artículo en Inglés | MEDLINE | ID: mdl-35475312

RESUMEN

Oxaliplatin, a platinum compound in broad clinical use, can induce cell death through a nucleolar stress pathway rather than the canonical DNA damage response studied for other Pt(II) compounds. Previous work has found that the oxaliplatin 1,2-diaminocyclohexane (DACH) ring but not the oxalate leaving group is important to the ability to induce nucleolar stress. Here we study the influence of DACH ring substituents at the 4-position on the ability of DACH-Pt(II) compounds to cause nucleolar stress. We determine that DACH-Pt(II) compounds with 4-position methyl, ethyl, or propyl substituents induce nucleolar stress, but DACH-Pt(II) compounds with 4-isopropyl substituents do not induce nucleolar stress. This effect is independent of whether the substituent is in the axial or equatorial position relative to the trans diamines of the ligand. These results suggest that spatially sensitive interactions could be involved in the ability of platinum compounds to cause nucleolar stress.


Asunto(s)
Antineoplásicos , Compuestos Organoplatinos , Antineoplásicos/farmacología , Ligandos , Compuestos Organoplatinos/metabolismo , Compuestos Organoplatinos/farmacología , Oxaliplatino/farmacología
10.
ACS Omega ; 7(8): 7257-7277, 2022 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-35252716

RESUMEN

A green and optimized protocol has been developed for the preparation of symmetric 1,7-bis(aryl)-1,6-heptadiene-3,5-diones and asymmetric 2-aryl-6-arylidenecyclohexanones with modified substrate scope and good functional group tolerance. Syntheses proceed smoothly under solvent-free conditions, providing moderate to excellent product yields with a minimal workup procedure. Control experiments, spectroscopic, and computational studies support a mechanism involving the boron-assisted in situ generation of imine intermediates. Crystal structures of three curcuminoids and isolated mechanistic intermediates are reported. The data provide insight for the further development of solvent-free protocols toward diverse curcumin derivatives in the fields of pharmaceutical and synthetic chemistries.

11.
ACS Appl Mater Interfaces ; 13(48): 57118-57131, 2021 Dec 08.
Artículo en Inglés | MEDLINE | ID: mdl-34817166

RESUMEN

Metal-organic frameworks (MOFs) are promising materials for the photocatalytic H2 evolution reaction (HER) from water. To find the optimal MOF for a photocatalytic HER, one has to consider many different factors. For example, studies have emphasized the importance of light absorption capability, optical band gap, and band alignment. However, most of these studies have been carried out on very different materials. In this work, we present a combined experimental and computation study of the photocatalytic HER performance of a set of isostructural pyrene-based MOFs (M-TBAPy, where M = Sc, Al, Ti, and In). We systematically studied the effects of changing the metal in the node on the different factors that contribute to the HER rate (e.g., optical properties, the band structure, and water adsorption). In addition, for Sc-TBAPy, we also studied the effect of changes in the crystal morphology on the photocatalytic HER rate. We used this understanding to improve the photocatalytic HER efficiency of Sc-TBAPy, to exceed the one reported for Ti-TBAPy, in the presence of a co-catalyst.

12.
ACS Appl Mater Interfaces ; 13(22): 26411-26420, 2021 Jun 09.
Artículo en Inglés | MEDLINE | ID: mdl-34034486

RESUMEN

Two-dimensional covalent organic frameworks (2D COFs) have attracted attention as versatile active materials in many applications. Recent advances have demonstrated the synthesis of monolayer 2D COF via an air-water interface. However, the interfacial 2D polymerization mechanism has been elusive. In this work, we have used a multiscale modeling strategy to study dimethylmethylene-bridged triphenylamine building blocks confined at the air-water interface to form a 2D COF via Schiff-base reaction. A synergy between the computational investigations and experiments allowed the synthesis of a 2D-COF with one of the linkers considered. Our simulations complement the experimental characterization and show the preference of the building blocks to be at the interface with a favorable orientation for the polymerization. The air-water interface is shown to be a key factor to stabilize a flat conformation when a dimer molecule is considered. The structural and electronic properties of the monolayer COFs based on the two monomers are calculated and show a semiconducting nature with direct bandgaps. Our strategy provides a first step toward the in silico polymerization of 2D COFs at air-water interfaces capturing the initial steps of the synthesis up to the prediction of electronic properties of the 2D material.

13.
Chem Soc Rev ; 50(5): 3143-3177, 2021 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-33475661

RESUMEN

Pyrene is one of the most widely investigated aromatic hydrocarbons given to its unique optical and electronic properties. Hence, pyrene-based ligands have been attractive for the synthesis of metal-organic frameworks (MOFs) in the last few years. In this review, we will focus on the most important characteristics of pyrene, in addition to the development and synthesis of pyrene-based molecules as bridging ligands to be used in MOF structures. We will summarize the synthesis attempts, as well as the post-synthetic modifications of pyrene-based MOFs by the incorporation of metals or ligands in the structure. The discussion of promising results of such MOFs in several applications; including luminescence, photocatalysis, adsorption and separation, heterogeneous catalysis, electrochemical applications and bio-medical applications will be highlighted. Finally, some insights and future prospects will be given based on the studies discussed in the review. This review will pave the way for the researchers in the field for the design and development of novel pyrene-based structures and their utilization for different applications.

14.
J Am Coll Radiol ; 17(8): 1011-1013, 2020 08.
Artículo en Inglés | MEDLINE | ID: mdl-32610104

RESUMEN

BACKGROUND: Quarantine and stay-at-home orders are strategies that many countries used during the acute pandemic period of coronavirus disease 2019 (COVID-19) to prevent disease dissemination, health system overload, and mortality. However, there are concerns that patients did not seek necessary health care because of these mandates. PURPOSE: To evaluate the differences in the clinical presentation of acute appendicitis and CT findings related to these cases between the COVID-19 acute pandemic period and nonpandemic period. MATERIALS AND METHODS: A retrospective observational study was performed to compare the acute pandemic period (March 23, 2020, to May 4, 2020) versus the same period the year before (March 23, 2019, to May 4, 2019). The proportion of appendicitis diagnosed by CT and level of severity of the disease were reviewed in each case. Univariate and bivariate analyses were performed to identify significant differences between the two groups. RESULTS: A total of 196 abdominal CT scans performed due to suspected acute appendicitis were evaluated: 55 from the acute pandemic period and 141 from the nonpandemic period. The proportion of acute appendicitis diagnosed by abdominal CT was higher in the acute pandemic period versus the nonpandemic period: 45.5% versus 29.8% (P = .038). The severity of the diagnosed appendicitis was higher during the acute pandemic period: 92% versus 57.1% (P = .003). CONCLUSION: During the acute COVID-19 pandemic period, fewer patients presented with acute appendicitis to the emergency room, and those who did presented at a more severe stage of the disease.


Asunto(s)
Apendicitis/diagnóstico por imagen , Apendicitis/epidemiología , Infecciones por Coronavirus/prevención & control , Control de Infecciones/organización & administración , Pandemias/prevención & control , Neumonía Viral/prevención & control , Tomografía Computarizada por Rayos X/estadística & datos numéricos , Análisis de Varianza , COVID-19 , Estudios de Cohortes , Infecciones por Coronavirus/epidemiología , Servicio de Urgencia en Hospital/estadística & datos numéricos , Femenino , Humanos , Incidencia , Masculino , Análisis Multivariante , Pandemias/estadística & datos numéricos , Neumonía Viral/epidemiología , Cuarentena/estadística & datos numéricos , Estudios Retrospectivos , Medición de Riesgo , Tomografía Computarizada por Rayos X/métodos , Estados Unidos
15.
Artículo en Inglés | MEDLINE | ID: mdl-32286980

RESUMEN

Phase retrieval is an inverse problem that consists in estimating a scene from diffraction intensities. This problem appears in optical imaging, which has three main diffraction zones where the measurements can be acquired, i.e., near, middle and far. Recent works have theoretically solved this inverse problem for the far zone, creating redundancy in the measurement process by including a coded aperture, which allows to modulate the scene and acquire coded diffraction patterns (CDP). However, in the state-of-the-art, the PR problem has not been theoretically studied for CDP at the near and middle zones. Moreover, the structure of the coded aperture is selected at random, leading to suboptimal estimations. Indeed, some of the coding elements employed in the literature are unfeasible because they increase the power of the scene in the modulation process. This paper provides theoretical guarantees for the recovery of a scene from CDP acquired at the three diffraction zones using admissible modulations. Based on the theoretical results, it is established that the image reconstruction quality directly depends on the coded aperture structure; therefore, a design strategy is proposed. In fact, when the scene can be sparsely represented in some basis, its support can be better estimated for a suitable choice of the coding elements in the modulation process. Experimental results show that the scene is successfully recovered by using designed coded apertures with up to 40% less measurements compared to non-designed ensembles.

16.
J Pediatr Orthop ; 40(1): e63-e67, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31022015

RESUMEN

BACKGROUND: A growing trend of survey-based research has been seen in the field of pediatric orthopaedics. The purpose of this study was to describe patterns of surveys of Pediatric Orthopaedic Society of North America (POSNA) membership and evaluate for associations between study characteristics and response rates in order to inform future research efforts. We hypothesized that studies with fewer survey questions and study group or committee involvement would demonstrate higher response rates. METHODS: A systematic review of the literature was performed to identify all peer-reviewed survey publications targeting POSNA members published up to December 2017. Included studies were reviewed to identify author and publication characteristics, survey development and methodology, survey distribution procedures, and response rates. Statistical analyses were performed to describe publication patterns and evaluate for associations between study characteristics and response rates. RESULTS: Thirty-four studies published from 1991 to 2017 were identified as meeting inclusion criteria, with a substantial increase noted over the last 3 years. Studies included 4.6 (SD 1.9) authors and 14.7% had affiliations with study groups or committees. Survey development methodology was detailed in only 1 study. Surveys included a median of 19.5 questions (3 to 108) and were primarily electronically distributed. The mean survey response rate was 42% with a downward trend noted over the studied time period. None of the studied author, publication, and design characteristics were associated with increased response rates. CONCLUSIONS: Survey-based studies of the POSNA membership have become increasingly popular study designs in recent years. Response rates are lower than reports in other physician cohorts, and appear to be declining, possibly representative of respondent fatigue. No associations were identified between response rates and the modifiable study characteristics evaluated (number of authors, committee or subgroup affiliation, number of questions, and mode of distribution). Efforts should be made to identify tactics to sustain participation as these studies become more widely utilized within our field. Optimizing study design and implementation features while valuing physician time and effort spent on survey completion is important to avoid member survey fatigue. LEVEL OF EVIDENCE: Level V-systematic review of Level V research.


Asunto(s)
Bibliometría , Ortopedia , Pediatría , Sociedades Médicas , Encuestas y Cuestionarios/estadística & datos numéricos , Autoria , Humanos , América del Norte , Publicaciones Periódicas como Asunto
17.
Hepatol Commun ; 3(10): 1400-1414, 2019 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-31592495

RESUMEN

CD73, a cell-surface N-linked glycoprotein that produces extracellular adenosine, is a novel target for cancer immunotherapy. Although anti-CD73 antibodies have entered clinical development, CD73 has both protumor and antitumor functions, depending on the target cell and tumor type. The aim of this study was to characterize CD73 regulation in human hepatocellular carcinoma (HCC). We examined CD73 expression, localization, and activity using molecular, biochemical, and cellular analyses on primary HCC surgical specimens, coupled with mechanistic studies in HCC cells. We analyzed CD73 glycan signatures and global alterations in transcripts encoding other N-linked glycoproteins by using mass spectrometry glycomics and RNA sequencing (RNAseq), respectively. CD73 was expressed on tumor hepatocytes where it exhibited abnormal N-linked glycosylation, independent of HCC etiology, tumor stage, or fibrosis presence. Aberrant glycosylation of tumor-associated CD73 resulted in a 3-fold decrease in 5'-nucleotidase activity (P < 0.0001). Biochemically, tumor-associated CD73 was deficient in hybrid and complex glycans specifically on residues N311 and N333 located in the C-terminal catalytic domain. Blocking N311/N333 glycosylation by site-directed mutagenesis produced CD73 with significantly decreased 5'-nucleotidase activity in vitro, similar to the primary tumors. Glycosylation-deficient CD73 partially colocalized with the Golgi structural protein GM130, which was strongly induced in HCC tumors. RNAseq analysis further revealed that N-linked glycoprotein-encoding genes represented the largest category of differentially expressed genes between HCC tumor and adjacent tissue. Conclusion: We provide the first detailed characterization of CD73 glycosylation in normal and tumor tissue, revealing a novel mechanism that leads to the functional suppression of CD73 in human HCC tumor cells. The present findings have translational implications for therapeutic candidate antibodies targeting cell-surface CD73 in solid tumors and small-molecule adenosine receptor agonists that are in clinical development for HCC.

18.
Anal Chem ; 91(11): 7254-7265, 2019 06 04.
Artículo en Inglés | MEDLINE | ID: mdl-30983332

RESUMEN

The recruitment of a bacterial consortium by the host is a strategy not limited to animals but is also used in plants. A maize aerial root mucilage has been found that harbors nitrogen fixing bacteria that are attracted to the carbohydrate rich environment. This synbiotic relationship is facilitated by a polysaccharide, whose complicated structure has been previously unknown. In this report, we present the characterization of the maize polysaccharide by employing new analytical strategies combining chemical depolymerization, oligosaccharide sequencing, and monosaccharide and glycosidic linkage quantitation. The mucilage contains a single heterogeneous polysaccharide composed of a highly fucosylated and xylosylated galactose backbone with arabinan and mannoglucuronan branches. This unique polysaccharide structure may select for the diazotrophic community by containing monosaccharides and linkages that correspond to the glycosyl hydrolases associated with the microbial community. The elucidation of this complicated structure illustrates the power of the analytical methods, which may serve as a general platform for polysaccharide analysis in the future.


Asunto(s)
Bacterias Fijadoras de Nitrógeno/química , Polisacáridos/análisis , Zea mays/química , Conformación de Carbohidratos , Cromatografía Líquida de Alta Presión , Espectrometría de Masas
19.
J Ethnobiol Ethnomed ; 12(1): 33, 2016 Aug 18.
Artículo en Inglés | MEDLINE | ID: mdl-27539307

RESUMEN

BACKGROUND: Traditional climate knowledge is a comprehensive system of insights, experiences and practices used by peasant communities to deal with the uncertainties of climate conditions affecting their livelihood. This knowledge is today as relevant in the Mesoamerican and Andean regions as it is in Europe and Asia. Our research sought to analyze the traditional knowledge about the weather and climate in a rural village of the state of Tlaxcala, Mexico, and its importance in decision-making in agriculture. METHODS: Through 30 interviews and participant observation in the community during 2013, information was gathered about traditional climate and weather indicators and prediction tools, as well as rituals and agronomic and agroforestry strategies. This information allowed for the reconstruction of the community's agro-festive calendar. Data analysis was carried out with the help of the qualitative analysis software Atlas.ti (version 7). RESULTS: The socio-ecological importance of traditional knowledge about the climate lies in its ability to forecast local weather conditions and recognize climate variations, so vital to the food security of rural families. Knowledge about climate predictors is exchanged and passed on from generation to generation, contributing to the preservation and promotion of biodiversity. By observing the behavior of 16 animals and 12 plant species (both domestic and wild) as well as seven astronomical indicators, villagers are able to predict rain, dry weather and frosts. However, the continuity of this traditional knowledge in the community under study is now compromised by the little interest in agriculture characteristic of the younger generations, the ensuing abandonment of the countryside, the widespread economic crisis and the disappearance of animal and plant species. CONCLUSIONS: Traditional climate knowledge includes the understanding of weather events and weather changes at different time scales (hours, days, weeks, and seasons). The ability to interpret weather events thanks to the accumulated knowledge about the climate through generations may prove today a relevant tool for improving agricultural practices and dealing with local and global socio-ecological changes.


Asunto(s)
Agricultura , Clima , Conocimiento , Animales , Astronomía , Biodiversidad , Abastecimiento de Alimentos , Humanos , México , Tiempo (Meteorología)
20.
Front Plant Sci ; 7: 743, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27379103

RESUMEN

To optimize the expression, extraction and purification of plant-derived tetrameric recombinant human butyrylcholinesterase (prBChE), we describe the development and use of plant viral amplicon-based gene expression system; Tobacco Mosaic Virus (TMV) RNA-based overexpression vector (TRBO) to express enzymatically active FLAG-tagged plant made recombinant butyrylcholinesterase (rBChE) in Nicotiana benthamiana leaves using transient agroinfiltration. Two gene expression cassettes were designed to express the recombinant protein in either the ER or to the apoplastic compartment. Leaf homogenization was used to isolate ER-retained recombinant butyrylcholinesterase (prBChE-ER) while apoplast-targeted rBChE was isolated by either leaf homogenization (prBChE) or vacuum-extraction of apoplastic wash fluid (prBChE-AWF). rBChE from apoplast wash fluid had a higher specific activity but lower enzyme yield than leaf homogenate. To optimize the isolation and purification of total recombinant protein from leaf homogenates, an acidic extraction buffer was used. The acidic extraction buffer yielded >95% enzymatically active tetrameric rBChE as verified by Coomassie stained and native gel electrophoresis. Furthermore, when compared to human butyrylcholinesterase, the prBChE was found to be similar in terms of tetramerization and enzyme kinetics. The N-linked glycan profile of purified prBChE-ER was found to be mostly high mannose structures while the N-linked glycans on prBChE-AWF were primarily complex. The glycan profile of the prBChE leaf homogenates showed a mixture of high mannose, complex and paucimannose type N-glycans. These findings demonstrate the ability of plants to produce rBChE that is enzymatically active and whose oligomeric state is comparable to mammalian butyrylcholinesterase. The process of plant made rBChE tetramerization and strategies for improving its pharmacokinetics properties are also discussed.

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