RESUMO
In recent years, the exploration of genome three-dimensional (3D) conformation has yielded profound insights into the regulation of gene expression and cellular functions in both animals and plants. While animals exhibit a characteristic genome topology defined by topologically associating domains (TADs), plants display similar features with a more diverse conformation across species. Employing advanced high-throughput sequencing and microscopy techniques, we investigated the landscape of 26 histone modifications and RNA polymerase II distribution in tomato (Solanum lycopersicum). Our study unveiled a rich and nuanced epigenetic landscape, shedding light on distinct chromatin states associated with heterochromatin formation and gene silencing. Moreover, we elucidated the intricate interplay between these chromatin states and the overall topology of the genome. Employing a genetic approach, we delved into the role of the histone modification H3K9ac in genome topology. Notably, our investigation revealed that the ectopic deposition of this chromatin mark triggered a reorganization of the 3D chromatin structure, defining different TAD-like borders. Our work emphasizes the critical role of H3K9ac in shaping the topology of the tomato genome, providing valuable insights into the epigenetic landscape of this agriculturally significant crop species.
Assuntos
Epigenoma , Histonas , Solanum lycopersicum , Solanum lycopersicum/genética , Solanum lycopersicum/metabolismo , Histonas/metabolismo , Histonas/genética , Epigênese Genética , Genoma de Planta , Cromatina/metabolismo , Cromatina/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Regulação da Expressão Gênica de Plantas , Heterocromatina/metabolismo , Heterocromatina/genética , Código das Histonas/genéticaRESUMO
The 3D chromatin organization plays a major role in the control of gene expression. However, our comprehension of the governing principles behind nuclear organization remains incomplete. Particularly, the spatial segregation of loci with similar repressive transcriptional states in plants poses a significant yet poorly understood puzzle. In this study, employing a combination of genetics and advanced 3D genomics approaches, we demonstrated that a redistribution of facultative heterochromatin marks in regions usually occupied by constitutive heterochromatin marks disrupts the 3D genome compartmentalisation. This disturbance, in turn, triggers novel chromatin interactions between genic and transposable element (TE) regions. Interestingly, our results imply that epigenetic features, constrained by genetic factors, intricately mold the landscape of 3D genome organisation. This study sheds light on the profound genetic-epigenetic interplay that underlies the regulation of gene expression within the intricate framework of the 3D genome. Our findings highlight the complexity of the relationships between genetic determinants and epigenetic features in shaping the dynamic configuration of the 3D genome.
RESUMO
Transcriptional silencing is an essential mechanism for controlling the expression of genes, transgenes and heterochromatic repeats through specific epigenetic marks on chromatin that are maintained during DNA replication. In Arabidopsis, silenced transgenes and heterochromatic sequences are typically associated with high levels of DNA methylation, while silenced genes are enriched in H3K27me3. Reactivation of these loci is often correlated with decreased levels of these repressive epigenetic marks. Here, we report that the DNA helicase REGULATOR OF TELOMERE ELONGATION 1 (RTEL1) is required for transcriptional silencing. RTEL1 deficiency causes upregulation of many genes enriched in H3K27me3 accompanied by a moderate decrease in this mark, but no loss of DNA methylation at reactivated heterochromatic loci. Instead, heterochromatin exhibits DNA hypermethylation and increased H3K27me3 in rtel1. We further find that loss of RTEL1 suppresses the release of heterochromatin silencing caused by the absence of the MOM1 silencing factor. RTEL1 is conserved among eukaryotes and plays a key role in resolving DNA secondary structures during DNA replication. Inducing such aberrant DNA structures using DNA cross-linking agents also results in a loss of transcriptional silencing. These findings uncover unappreciated roles for RTEL1 in transcriptional silencing and in stabilizing DNA methylation and H3K27me3 patterns.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , DNA Helicases , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Metilação de DNA/genética , Epigenoma , Inativação Gênica , Heterocromatina/genética , Heterocromatina/metabolismo , Histonas/genética , Histonas/metabolismo , Telômero/metabolismo , DNA Helicases/metabolismoRESUMO
Selection of C-terminal motifs participated in evolution of distinct histone H2A variants. Hybrid types of variants combining motifs from distinct H2A classes are extremely rare. This suggests that the proximity between the motif cases interferes with their function. We studied this question in flowering plants that evolved sporadically a hybrid H2A variant combining the SQ motif of H2A.X that participates in the DNA damage response with the KSPK motif of H2A.W that stabilizes heterochromatin. Our inventory of PTMs of H2A.W variants showed that in vivo the cell cycle-dependent kinase CDKA phosphorylates the KSPK motif of H2A.W but only in absence of an SQ motif. Phosphomimicry of KSPK prevented DNA damage response by the SQ motif of the hybrid H2A.W/X variant. In a synthetic yeast expressing the hybrid H2A.W/X variant, phosphorylation of KSPK prevented binding of the BRCT-domain protein Mdb1 to phosphorylated SQ and impaired response to DNA damage. Our findings illustrate that PTMs mediate interference between the function of H2A variant specific C-terminal motifs. Such interference could explain the mutual exclusion of motifs that led to evolution of H2A variants.
Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Histonas/genética , Processamento de Proteína Pós-Traducional , Schizosaccharomyces/genética , Sequência de Aminoácidos , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Técnicas de Cultura de Células , Ciclo Celular/genética , Proteínas Cromossômicas não Histona/genética , Proteínas Cromossômicas não Histona/metabolismo , Quinases Ciclina-Dependentes/genética , Quinases Ciclina-Dependentes/metabolismo , Dano ao DNA , Evolução Molecular , Heterocromatina/química , Heterocromatina/metabolismo , Histonas/metabolismo , Fosforilação , Células Vegetais/metabolismo , Plantas Geneticamente Modificadas , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Schizosaccharomyces/metabolismo , Proteínas de Schizosaccharomyces pombe/genética , Proteínas de Schizosaccharomyces pombe/metabolismo , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , TransgenesRESUMO
Drowning is the leading cause of death by accident of everyday life in people under 25 years of age. Xenobiotics are frequently involved in drowning cases but their influence on the diagnosis of fatal drowning has not been studied so far. This preliminary study aimed to assess the influence of an alcohol and/or a drug intoxication on the autopsy signs of drowning, and on the results of diatom analyses in drowning deaths. Twenty-eight autopsy cases of drowning including 19 freshwater drownings, 6 seawater drownings, and 3 brackish water drownings were prospectively included. Toxicological and diatom tests were performed in each case. The influence of alcohol and other xenobiotics on drowning signs and diatom analyses was assessed separately then in combination through a global toxicological participation score (GTPS). Diatom analyses showed positive results in lung tissue in every case. No significant association was found between the degree of intoxication and the diatom concentration in the organs, even after considering freshwater drowning cases only. The vast majority of the traditional autopsy signs of drowning were not significantly affected by the individual toxicological status either, with the exception of lung weight which tended to raise in case of intoxication, probably due to the pulmonary edema and congestion increase. Further research on larger autopsy samples is needed to confirm the results of this exploratory study.
Assuntos
Diatomáceas , Afogamento , Humanos , Afogamento/diagnóstico , Xenobióticos , Autopsia , Etanol , PulmãoRESUMO
The combustion properties of a gasoline-like blend of pentene isomers were determined using multiple types of experimental measurements. The representative mixture (Mix A) is composed of 5.7% 1-pentene (1-C5H10), 39.4% 2-pentene (2-C5H10), 12.5% 2-methyl-1-butene (2M1B), and 42.4% 2-methyl-2-butene (2M2B) (% mol). Laminar flame speeds were measured at equivalence ratios of 0.7-1.5 in a constant-volume combustion chamber, and ignition delay times (including both OH* and CH* diagnostics) as well as CO time-history profiles were performed in shock tubes, in highly diluted mixtures (0.995 He/Ar), at a stoichiometric condition for temperatures ranging from 1350 to 1750 K, and at near-atmospheric pressure. Two additional unbalanced mixtures removing either 2M2B (Mix B) or 2-C5H10 (Mix C) were studied in a shock tube to collect CO time histories, representing the most stringent validation constraints, as these two pentenes constitute the biggest proportions in Mix A and exhibit opposite behaviors in terms of reactivity due to their chemical structure differences. Numerical predictions using a recent validated chemical kinetics mechanism encompassing all pentene isomers from Grégoire et al. ( Fuel2022, 323, 124223) are presented. The use of a complex blend of four pentene isomers in the present paper provided a capstone test of the current mechanism's ability to model pentene-isomer combustion chemistry, with very good results that reflect positively on the current state of the art in pentene isomer kinetics modeling.
RESUMO
Recent evidence suggests that lactic acid bacteria communicate with host cells via secretome components to influence immune responses but less is known about gut-pathogen secretomes, impact of lactic acid bacteria secretomes on host-pathogen interactions, and the mechanisms underlying these interactions. Genome-wide microarrays and cytokine profiling were used to interrogate the impact of the Lactobacillus rhamnosus R0011 secretome (LrS) on TNF-α and Salmonella enterica subsp. enterica serovar Typhimurium secretome (STS)-induced outcomes in human intestinal epithelial cells. The LrS attenuated both TNF-α- and STS-induced gene expression involved in NF-κB and MAPK activation, as well as expression of genes involved in other immune-related signaling pathways. Specifically, the LrS induced the expression of dual specificity phosphatase 1 (DUSP1), activating transcription factor 3 (ATF3), and tribbles pseudokinase 3 (TRIB3), negative regulators of innate immune signaling, in HT-29 intestinal epithelial cells challenged with TNF-α or STS. TNF-α- and STS-induced acetylation of H3 and H4 histones was attenuated by the LrS, as was the production of TNF-α- and STS-induced proinflammatory cytokines and chemokines. Interestingly, the LrS induced production of macrophage migration inhibitory factor (MIF), a cytokine involved in host-microbe interactions at the gut interface. We propose that the LrS attenuates proinflammatory mediator expression through increased transcription of negative regulators of innate immune activity and changes in global H3 and H4 histone acetylation. To our knowledge, these findings provide novel insights into the complex multifaceted mechanisms of action behind secretome-mediated interdomain communication at the gut-mucosal interface.
Assuntos
Células Epiteliais/imunologia , Inflamação/imunologia , Intestinos/imunologia , Lacticaseibacillus rhamnosus/imunologia , Salmonelose Animal/imunologia , Salmonella typhimurium/imunologia , Fator de Necrose Tumoral alfa/imunologia , Acetilação , Animais , Linhagem Celular Tumoral , Citocinas/imunologia , Células Epiteliais/microbiologia , Expressão Gênica/imunologia , Células HT29 , Histonas/imunologia , Interações Hospedeiro-Patógeno/imunologia , Humanos , Imunidade Inata/imunologia , Inflamação/microbiologia , Mucosa Intestinal/imunologia , Mucosa Intestinal/microbiologia , Intestinos/microbiologia , Fatores Inibidores da Migração de Macrófagos/imunologia , Proteínas Quinases Ativadas por Mitógeno/metabolismo , NF-kappa B/metabolismo , Salmonelose Animal/microbiologia , Sorogrupo , Transdução de Sinais/fisiologia , Transcrição Gênica/imunologiaRESUMO
OBJECTIVES: Methotrexate requires therapeutic drug monitoring in oncology because of narrow therapeutic index, especially the metabolite 7-hydroxymethotrexate exhibits nephrotoxicity. The goal of this study was to evaluate different assays and their impact on clinical decisions. METHODS: Following routine measurement with Abbott TDxFLx® assay (MTX-TDX), 62 samples were analysed on Architect®i1000 (MTX-ARCHI), Xpand® (ARK/XPND), Indiko® (ARK/INDI), and HPLC (MTX-HPLC) as the reference method. The influence of 7-hydroxymethotrexate was explored on ARK reagent to document the cause of the observed bias. ROC curves were built to study the impact of the method on the discharge thresholds for the patients at three levels. RESULTS: Total imprecision was below 2.60% for the methotrexate-ARCHI and close to 10% for both ARK assays for plasma pools. The correlation coefficients were 0.93, 0.93, 0.89 and 0.95, the Bland-Altman difference plot revealed a bias of 0.075, 0.037, 0.049 and -0.002, and the number of results exceeding the TE criteria of 0.1 µM was 17 (27%), 13 (21%), 15 (24%) and 15 (24%) for MTX-TDX, ARK/INDI, ARK/XPND and MTX-ARCHI, respectively. Cross reactivity with 7-hydroxymethotrexate was between 1 and 9%. Overestimation of methotrexate concentration was between -4% and +32%. The most robust clinical level was found to be the highest level (0.2 µM) with ROC curves. CONCLUSIONS: The authors found the best results for imprecision with chemiluminescent microparticle immunoassay method on methotrexate-ARCHI, with bias below to the RICOS recommendations and best correlation to the reference method. Impact on the threshold values for clinical decision need to be clearly exposed to clinicians.
Assuntos
Monitoramento de Medicamentos , Metotrexato , Cromatografia Líquida de Alta Pressão , Imunoensaio de Fluorescência por Polarização , Humanos , ImunoensaioRESUMO
The two paralogous Arabidopsis genes MAINTENANCE OF MERISTEMS (MAIN) and MAINTENANCE OF MERISTEMS LIKE1 (MAIL1) encode a conserved retrotransposon-related plant mobile domain and are known to be required for silencing of transposable elements (TE) and for primary root development. Loss of function of either MAIN or MAIL1 leads to release of heterochromatic TEs, reduced condensation of pericentromeric heterochromatin, cell death of meristem cells and growth arrest of the primary root soon after germination. Here, we show that they act in one protein complex that also contains the inactive isoform of PROTEIN PHOSPHATASE 7 (PP7), which is named PROTEIN PHOSPHATASE 7-LIKE (PP7L). PP7L was previously shown to be important for chloroplast biogenesis and efficient chloroplast protein synthesis. We show that loss of PP7L function leads to the same root growth phenotype as loss of MAIL1 or MAIN. In addition, pp7l mutants show similar silencing defects. Double mutant analyses confirmed that the three proteins act in the same molecular pathway. The primary root growth arrest, which is associated with cell death of stem cells and their daughter cells, is a consequence of genome instability. Our data demonstrate so far unrecognized functions of an inactive phosphatase isoform in a protein complex that is essential for silencing of heterochromatic elements and for maintenance of genome stability in dividing cells.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Elementos de DNA Transponíveis/genética , Proteínas Nucleares/metabolismo , Fosfoproteínas Fosfatases/metabolismo , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/fisiologia , Proteínas de Arabidopsis/genética , Cloroplastos/metabolismo , Inativação Gênica , Germinação , Heterocromatina/genética , Isoenzimas , Meristema/genética , Meristema/crescimento & desenvolvimento , Meristema/fisiologia , Mutação , Proteínas Nucleares/genética , Fenótipo , Fosfoproteínas Fosfatases/genética , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/fisiologia , Retroelementos/genéticaRESUMO
BACKGROUND: Levobupivacaine is commonly used during transversus abdominis plane (TAP) block in pediatric patients. However, the dosing regimen is still empirical, and the pharmacokinetic properties of levobupivacaine are not considered. Here, the pharmacokinetics of levobupivacaine during an ultrasound-guided TAP block were evaluated to optimize dosing regimen, regarding the between-subject variability (BSV) and the volume of levobupivacaine injected. METHOD: The clinical trial (prospective, randomized, double-blind study protocol) was conducted in 40 children aged 1-5 years, who were scheduled for inguinal surgery. Each patient received 0.4 mg/kg of levobupivacaine with a volume of local anesthesia solution adjusted to 0.2 mL/kg of 0.2% or 0.4 mL/kg of 0.1% levobupivacaine. Blood samples were collected at 5, 15, 20, 25, 30, 45, 60, and 75 minutes after the block injection. The population pharmacokinetic analysis was performed using the NONMEM software. RESULTS: From the pharmacokinetic parameters obtained, median Cmax, tmax,, and area under the concentration versus time curve were 0.315 mg/L, 17 minutes, and 41 mg/L·min, respectively. BSV of clearance was explained by weight. At the dose regimen of 0.4 mg/kg, none of the infants showed signs of toxicity, but in 13 patients, TAP block failed. After analysis, BSV for absorption rate constant, distribution volume, and clearance were 81%, 47%, and 41%, respectively. Residual unexplained variability was estimated to be 14%. CONCLUSIONS: For improved efficiency in the pediatric population, the dose of levobupivacaine should be greater than 0.4 mg/kg. Children's weight should be considered to anticipate any risk of toxicity.
Assuntos
Anestésicos Locais/farmacocinética , Levobupivacaína/farmacocinética , Bloqueio Nervoso/métodos , Músculos Abdominais Oblíquos/inervação , Área Sob a Curva , Peso Corporal , Pré-Escolar , Relação Dose-Resposta a Droga , Método Duplo-Cego , Feminino , Humanos , Lactente , Masculino , Taxa de Depuração Metabólica , Estudos ProspectivosRESUMO
Phosphine (PH3) is a highly reactive and toxic gas. Prior experimental investigations of PH3 pyrolysis reactions have included only low-temperature measurements. This study reports the first shock-tube measurements of PH3 pyrolysis using a new PH3 laser absorption technique near 4.56 µm. Experiments were conducted in mixtures of 0.5% PH3/Ar behind reflected shock waves at temperatures of 1460-2013 K and pressures of â¼1.3 and â¼0.5 atm. The PH3 time histories displayed two-stage behavior similar to that previously observed for NH3 decomposition, suggesting by analogy that the rate constant for PH3 + M â PH2 + H + M (R1) could be determined. A simple three-step mechanism was assembled for data analysis. In a detailed kinetic analysis of the first-stage PH3 decomposition, values of k1,0 were obtained and best described by (in cm3·mol-1·s-1) k1,0 = 7.78 × 1017 exp(-80,400/RT), with units of cal, mol, K, s, and cm3. Agreement between the 1.3 and 0.5 atm data confirmed that the measured k1,0 was in the low-pressure limit. Agreement of the experimental k1,0 with ab initio estimates resolved the question of the main pathway of PH3 decomposition: it proceeds as PH3 â PH2 + H instead of PH3 â PH + H2.
RESUMO
BACKGROUND: The transversus abdominis plane (TAP) block has become a common regional anesthesia technique for pain management in a wide variety of abdominal procedures. Evidence to support any particular local anesthetic regimen as well as pharmacokinetic and systemic toxicity risks of TAP block remain insufficiently studied in children. The aim of this study was to compare the analgesic effects and investigate pharmacokinetic profile of levobupivacaine after ultrasound-guided TAP block using a low volume/high concentration (LVHC) or a high volume/low concentration (HVLC) solution in children. METHODS: This prospective randomized study included children scheduled for day-case inguinal surgery. Children were randomized to receive TAP block using 0.4 mg·kg levobupivacaine as either HVLC (0.2 mL·kg of 0.2% levobupivacaine) or LVHC (0.1 mL·kg of 0.4% levobupivacaine). The primary outcome was the number of children who required opioid rescue analgesia postoperatively. Pharmacokinetic profile study of levobupivacaine was also performed. RESULTS: Seventy patients were equally randomized, and 65 were included in the final analysis. Seventy-one percent of patients did not require any postoperative opioid analgesia. The number of patients who received rescue analgesia was 12 (35%) in the LVHC group and 7 (23%) in the HVLC group (relative risk, 0.64; 95% confidence interval [CI], 0.29-1.42; P = .26). Mean pain scores (FLACC [faces, legs, activity, cry, and consolability]) at postanesthesia care unit discharge did not differ between LVHC and HVLC groups, respectively, 0.39 ± 0.86 and 1 ± 1.71 with mean group difference -0.60 (95% CI, -1.27 to 0.06; P = .08). The pharmacokinetic profile of levobupivacaine was comparable in the 2 groups: the mean total and free levobupivacaine peak concentrations were 379 ± 248 and 3.95 ± 3.16 ng·mL, respectively, occurring 22.5 ± 11 minutes after injection. The highest total and free levobupivacaine concentrations collected, respectively, 1360 and 15.1 ng·mL, remained far below theoretical toxic thresholds. CONCLUSIONS: In children, quality of postoperative pain control provided by TAP block using levobupivacaine 0.4 mg·kg administered as either HVLC or LVHC did not differ and was associated with a very low risk of local anesthetic systemic toxicity.
Assuntos
Músculos Abdominais/efeitos dos fármacos , Anestesia Local/métodos , Levobupivacaína/farmacocinética , Bloqueio Nervoso/métodos , Analgesia/métodos , Analgésicos Opioides/farmacocinética , Anestésicos Locais/farmacocinética , Bupivacaína/farmacocinética , Pré-Escolar , Método Duplo-Cego , Feminino , Humanos , Lactente , Masculino , Manejo da Dor/métodos , Dor Pós-Operatória/tratamento farmacológico , Estudos Prospectivos , UltrassonografiaRESUMO
Genes and transposons can exist in variable DNA methylation states, with potentially differential transcription. How these epialleles emerge is poorly understood. Here, we show that crossing an Arabidopsis thaliana plant with a hypomethylated genome and a normally methylated WT individual results, already in the F1 generation, in widespread changes in DNA methylation and transcription patterns. Novel nonparental and heritable epialleles arise at many genic loci, including a locus that itself controls DNA methylation patterns, but with most of the changes affecting pericentromeric transposons. Although a subset of transposons show immediate resilencing, a large number display decreased DNA methylation, which is associated with de novo or enhanced transcriptional activation and can translate into transposon mobilization in the progeny. Our findings reveal that the combination of distinct epigenomes can be viewed as an epigenomic shock, which is characterized by a round of epigenetic variation creating novel patterns of gene and TE regulation.
Assuntos
Arabidopsis/genética , Metilação de DNA , Elementos de DNA Transponíveis , Epigênese Genética , Inativação Gênica , Genoma de Planta , Hibridização Genética , Transcrição GênicaRESUMO
DNA methylation is an epigenetic mark that ensures silencing of transposable elements (TEs) and affects gene expression in many organisms. The function of different DNA methylation regulatory pathways has been largely characterized in the model plant Arabidopsis thaliana. However, far less is known about DNA methylation regulation and functions in basal land plants. Here we focus on the liverwort Marchantia polymorpha, an emerging model species that represents a basal lineage of land plants. We identified MpMET, the M. polymorpha ortholog of the METHYLTRANSFERASE 1 (MET1) gene required for maintenance of methylation at CG sites in angiosperms. We generated Mpmet mutants using the CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated protein9) system, which showed a significant loss of CG methylation and severe morphological changes and developmental defects. The mutants developed many adventitious shoot-like structures, suggesting that MpMET is required for maintaining differentiated cellular identities in the gametophyte. Even though numerous TEs were up-regulated, non-CG methylation was generally highly increased at TEs in the Mpmet mutants. Closer inspection of CHG methylation revealed features unique to M. polymorpha. Methylation of CCG sites in M. polymorpha does not depend on MET1, unlike in A. thaliana and Physcomitrella patens. Our results highlight the diversity of non-CG methylation regulatory mechanisms in plants.
Assuntos
Divisão Celular/genética , Ilhas de CpG/genética , Metilação de DNA/genética , Marchantia/citologia , Marchantia/genética , Elementos de DNA Transponíveis/genética , Genoma de Planta , Mutação/genéticaRESUMO
In soil, the link between microbial diversity and carbon transformations is challenged by the concept of functional redundancy. Here, we hypothesized that functional redundancy may decrease with increasing carbon source recalcitrance and that coupling of diversity with C cycling may change accordingly. We manipulated microbial diversity to examine how diversity decrease affects the decomposition of easily degradable (i.e., allochthonous plant residues) versus recalcitrant (i.e., autochthonous organic matter) C sources. We found that a decrease in microbial diversity (i) affected the decomposition of both autochthonous and allochthonous carbon sources, thereby reducing global CO2 emission by up to 40%, and (ii) shaped the source of CO2 emission toward preferential decomposition of most degradable C sources. Our results also revealed that the significance of the diversity effect increases with nutrient availability. Altogether, these findings show that C cycling in soil may be more vulnerable to microbial diversity changes than expected from previous studies, particularly in ecosystems exposed to nutrient inputs. Thus, concern about the preservation of microbial diversity may be highly relevant in the current global-change context assumed to impact soil biodiversity and the pulse inputs of plant residues and rhizodeposits into the soil.IMPORTANCE With hundreds of thousands of taxa per gram of soil, microbial diversity dominates soil biodiversity. While numerous studies have established that microbial communities respond rapidly to environmental changes, the relationship between microbial diversity and soil functioning remains controversial. Using a well-controlled laboratory approach, we provide empirical evidence that microbial diversity may be of high significance for organic matter decomposition, a major process on which rely many of the ecosystem services provided by the soil ecosystem. These new findings should be taken into account in future studies aimed at understanding and predicting the functional consequences of changes in microbial diversity on soil ecosystem services and carbon storage in soil.
Assuntos
Carbono/metabolismo , Ecossistema , Microbiota , Microbiologia do Solo , Bactérias/classificação , Fungos/classificaçãoRESUMO
BACKGROUND: The measurement of carbon isotopic discrimination in grape sugars at harvest (δ13 C) is an integrated assessment of water status during ripening. It is an efficient alternative to assess variability in the field and discriminate between management zones in precision viticulture, but further work is needed to completely understand the signal. RESULTS: This work, spanning over 3 years, performed in a hillslope toposequence in Burgundy, delineates the relationships between main soil properties (gravel amount, slope, texture) and the grapevine water status assessed by δ13 C. The highest δ13 C, indicating most severe water deficit, was recorded in gravelly soils on steep slopes. The amount of sugars and malic and tartaric acids was also related to δ13 C. The relationship between δ13 C and predawn leaf water potentials (Ψpd ) was also investigated, because the absolute values of measured δ13 C were lower than the values currently found in the literature. CONCLUSIONS: A mini-meta-analysis was performed, which showed that the slope of the relationships between minimum Ψpd and δ13 C was stable across studies (a change of 1 in δ13 C corresponded to a change of -0.2 MPa in the minimum Ψpd ), while the intercept of the comparison δ13 C/Ψpd changed, probably because of genetic variations between varieties, or environmental differences. © 2017 Society of Chemical Industry.
Assuntos
Solo/classificação , Vitis/fisiologia , Água/fisiologia , Metabolismo dos Carboidratos , Isótopos de Carbono , Manipulação de Alimentos , Frutas/química , Folhas de Planta/química , Folhas de Planta/metabolismo , Solo/química , VinhoRESUMO
Designer benzodiazepines (DBZDs) have become of particular importance in the past few years. The metabolite monitoring of DBZD in biological fluids could be of great interest in clinical and forensic toxicology. However, DBZD metabolites are not known or not commercially available. The identification of some DBZD metabolites has been mostly explored by self-administration studies or by in vitro studies followed by high-resolution mass spectrometry. The question arose whether a unit resolution instrument could be efficient enough to allow the identification of DBZD metabolites. In this study, we used an in vitro experiment where eight DBZDs (diclazepam, flubromazepam, etizolam, deschloroetizolam, flubromazolam, nifoxipam, meclonazepam and clonazolam) were incubated with human liver microsomes (HLMs) and metabolite identification was carried out by using a UHPLC coupled to a QTRAP triple quadrupole linear iontrap tandem mass spectrometer system. Post-mortem samples obtained from a real poisoning case, involving deschloroetizolam and diclazepam, were also analysed and discussed. Our study using HLM allowed the identification of 26 metabolites of the 8 DBZDs. These were denitro-, mono- or di-hydroxylated and desmethyl metabolites. In the forensic case, diclazepam was not detected whereas its metabolites (lormetazepam and lorazepam) were present at high concentrations in urine. We also identified hydroxy-deschloroetizolam in urine, while the parent compound was not detected in this matrix. This supports the approach that LC coupled to a simple QTRAP could be used by laboratories to identify other not-known/not-commercialized new psychoactive substance (NPS) metabolites.
Assuntos
Benzodiazepinas/química , Drogas Desenhadas/química , Microssomos Hepáticos/química , Adulto , Benzodiazepinas/análise , Cromatografia Líquida , Drogas Desenhadas/análise , Humanos , Lorazepam/análogos & derivados , Lorazepam/urina , Masculino , Oxazepam/urina , Transtornos Relacionados ao Uso de Substâncias/urina , Espectrometria de Massas em TandemRESUMO
BACKGROUND: Recurrent Clostridium difficile infection (RCDI) is associated with repeated antibiotic treatment and the enhanced growth of antibiotic-resistant microbes. This study tested the hypothesis that patients with RCDI would harbor large numbers of antibiotic-resistant microbes and that fecal microbiota transplantation (FMT) would reduce the number of antibiotic-resistant genes. METHODS: In a single center study, patients with RCDI (n = 20) received FMT from universal donors via colonoscopy. Stool samples were collected from donors (n = 3) and patients prior to and following FMT. DNA was extracted and shotgun metagenomics performed. Results as well as assembled libraries from a healthy cohort (n = 87) obtained from the Human Microbiome Project were aligned against the NCBI bacterial taxonomy database and the Comprehensive Antibiotic Resistance Database. Results were corroborated through a DNA microarray containing 354 antibiotic resistance (ABR) genes. RESULTS: RCDI patients had a greater number and diversity of ABR genes compared with donors and healthy controls. Beta-lactam, multidrug efflux pumps, fluoroquinolone, and antibiotic inactivation ABR genes were increased in RCDI patients, although donors primarily had tetracycline resistance. RCDI patients were dominated by Proteobacteria with Escherichia coli and Klebsiella most prevalent. FMT resulted in a resolution of symptoms that correlated directly with a decreased number and diversity of ABR genes and increased Bacteroidetes and Firmicutes with reduced Proteobacteria. ABR gene profiles were maintained in recipients for up to a year following FMT. CONCLUSIONS: RCDI patients have increased numbers of antibiotic-resistant organisms. FMT is effective in the eradication of pathogenic antibiotic-resistant organisms and elimination of ABR genes.
Assuntos
Clostridioides difficile/efeitos dos fármacos , Farmacorresistência Bacteriana/genética , Enterocolite Pseudomembranosa/terapia , Transplante de Microbiota Fecal , Microbioma Gastrointestinal/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Antibacterianos/farmacologia , Clostridioides difficile/genética , Enterocolite Pseudomembranosa/microbiologia , Fezes/microbiologia , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
The stability of epigenetic patterns is critical for genome integrity and gene expression. This highly coordinated process involves interrelated positive and negative regulators that impact distinct epigenetic marks, including DNA methylation and dimethylation at histone H3 lysine 9 (H3K9me2). In Arabidopsis, mutations in the DNA methyltransferase MET1, which maintains CG methylation, result in aberrant patterns of other epigenetic marks, including ectopic non-CG methylation and the relocation of H3K9me2 from heterochromatin into gene-rich chromosome regions. Here, we show that the expression of the H3K9 demethylase IBM1 (increase in BONSAI methylation 1) requires DNA methylation. Surprisingly, the regulatory methylated region is contained in an unusually large intron that is conserved in IBM1 orthologues. The re-establishment of IBM1 expression in met1 mutants restored the wild-type H3K9me2 nuclear patterns, non-CG DNA methylation and transcriptional patterns at selected loci, which included DNA demethylase genes. These results provide a mechanistic explanation for long-standing puzzling observations in met1 mutants and reveal yet another layer of control in the interplay between DNA methylation and histone modification, which stabilizes DNA methylation patterns at genes.