RESUMO
BACKGROUND: Gastric and esophageal cancers are malignant diseases with rising importance in Western countries. To improve oncologic outcome after surgery, it is essential to understand the relevance of germline mutations. The aim of the study was to identify and distinguish clinically relevant single-nucleotide polymorphisms (SNPs). PATIENTS AND METHODS: In total, 190 patients with curative oncological resections of gastric and distal esophageal adenocarcinomas at Heidelberg University Hospital were eligible for this study. Outcome differences were determined for each SNP by analysis of clinical variables, survival, and mRNA expression levels. RESULTS: Significant survival differences were found on univariate analysis for usual prognostic variables (such as pTNM) and for six SNPs. On multivariate survival analysis, the SNPs rs12268840 (intron variant of MGMT, p = 0.045) and rs9972882 (intron variant of STARD3 and eQTL of PGAP3, p = 0.030) were independent and significant survival predictors along with R status and pT/pN category. Group TT of rs12268840 had the highest rate of second primary carcinoma (30.4%, p = 0.0003), lowest expression of MGMT based on cis-eQTL analysis in normal gastroesophageal tissue (p = 1.99 × 10-17), and worst oncologic outcome. Group AA of rs9972882 had the highest rate of distant metastases pM1 (42.9%, p = 0.0117), highest expression of PGAP3 (p = 1.29 × 10-15), and worst oncologic outcome. CONCLUSIONS: Two intron variant SNPs of MGMT and STARD3 were identified that were significant survival predictors and may influence tumor biology. The data indicate that DNA methylation (MGMT) and malfunction of GPI anchoring (PGAP3) are distinct mechanisms that are relevant for tumor progression and relapse.
Assuntos
Neoplasias Esofágicas , Neoplasias Gástricas , Metilação de DNA , Neoplasias Esofágicas/genética , Neoplasias Esofágicas/cirurgia , Humanos , Recidiva Local de Neoplasia/genética , Recidiva Local de Neoplasia/cirurgia , Polimorfismo de Nucleotídeo Único , Prognóstico , Neoplasias Gástricas/genética , Neoplasias Gástricas/cirurgiaRESUMO
MAIN CONCLUSION: Smut pathogen induced an early modulation of the production and scavenging of reactive oxygen species during defence responses in resistant sugarcane that coincided with the developmental stages of fungal growth. Sporisorium scitamineum is the causal agent of sugarcane smut disease. In this study, we characterized sugarcane reactive oxygen species (ROS) metabolism in response to the pathogen in smut-resistant and -susceptible genotypes. Sporisorium scitamineum teliospore germination and appressorium formation coincided with H2O2 accumulation in resistant plants. The superoxide dismutase (SOD) activity was not responsive in any of the genotypes; however, a higher number of isoenzymes were detected in resistant plants. In addition, related to resistance were lipid peroxidation, a decrease in catalase (CAT), and an increase in glutathione S-transferase (GST) activities and an earlier transcript accumulation of ROS marker genes (CAT3, CATA, CATB, GST31, GSTt3, and peroxidase 5-like). Furthermore, based on proteomic data, we suggested that the source of the increased hydrogen peroxide (H2O2) may be due to a protein of the class III peroxidase, which was inhibited in the susceptible genotype. H2O2 is sensed and probably transduced through overlapping systems related to ascorbate-glutathione and thioredoxin to influence signalling pathways, as revealed by the presence of thioredoxin h-type, ascorbate peroxidase, and guanine nucleotide-binding proteins in the infected resistant plants. Altogether, our data depicted the balance of the oxidative burst and antioxidant enzyme activity in the outcome of this interaction.
Assuntos
Doenças das Plantas/microbiologia , Explosão Respiratória/fisiologia , Saccharum/fisiologia , Ustilago/patogenicidade , Suscetibilidade a Doenças/metabolismo , Regulação da Expressão Gênica de Plantas/fisiologia , Genótipo , Peróxido de Hidrogênio/metabolismo , Peroxidação de Lipídeos , Espécies Reativas de Oxigênio/metabolismo , Saccharum/microbiologiaRESUMO
Many aspects related to ROS modulation of signaling networks and biological processes that control stress responses still remain unanswered. For this purpose, the grafting technique may be a powerful tool to investigate stress signaling and specific responses between plant organs during stress. In order to gain new insights on the modulation of antioxidant stress responses mechanisms, gas-exchange measurements, lipid peroxidation, H2O2 content, proline, superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), ascorbate peroxidase (APX) and guaiacol peroxidase (GPOX) were analyzed in Micro-Tom grafted plants submitted to cadmium (Cd). The results observed revealed that higher amounts of Cd accumulated mainly in the roots and rootstocks when compared to leaves and scions. Macronutrients uptake (Ca, S, P and Mg) decreased in non-grafted plants, but differed among plant parts in all grafted plants. The results showed that the accumulation of proline observed in scions of grafted plants could be associated to the lower MDA contents in the scions of grafted plants. In the presence of Cd, non-grafted plants displayed increased CAT, GR, GPOX and APX activities for both tissues, whilst grafted plants revealed distinct trends that clearly indicate signaling responses from the rootstocks, allowing sufficient time to activate defense mechanisms in shoot. The information available concerning plants subjected to grafting can provide a better understanding of the mechanisms of Cd detoxification involving root-to-shoot signaling, opening new possibilities on strategies which can be used to manipulate heavy metal tolerance, since antioxidant systems are directly involved in such mechanism.
Assuntos
Antioxidantes/metabolismo , Cádmio/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Solanum lycopersicum/crescimento & desenvolvimento , Ascorbato Peroxidases/metabolismo , Catalase/metabolismo , Glutationa Redutase/metabolismo , Peróxido de Hidrogênio/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Solanum lycopersicum/efeitos dos fármacos , Solanum lycopersicum/genética , Desintoxicação Metabólica Fase I/genética , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Brotos de Planta/efeitos dos fármacos , Brotos de Planta/metabolismo , Superóxido Dismutase/metabolismoRESUMO
Paracoccidioidomycosis is an infection with the potential for environmental dissemination, especially in regions of hot and humid climate, where human cases have been recorded in the Southwestern Amazon of Brazil, specifically in the state of Acre. Despite studies providing information about the presence of these fungi in soil and animal samples, such as armadillos, further investigations are still needed to determine the epidemiological distribution of the genus Paracoccidioides. The aim of this study was to detect the occurrence of Paracoccidioides fungi in the Southwestern Amazon. To achieve this, 60 soil samples were collected from armadillo burrows on rural properties in the in the municipalities of Acrelândia, Bujari, Plácido de Castro, Rio Branco, Sena Madureira, and Senador Guiomard, located in the state of Acre, Brazil. Fungal DNA was extracted from these samples using the DNEASY® PowerSoil kit-Quiagen, followed by Nested PCR technique with ITS4 and ITS5 as external primers, and PBITS-E and PBITS-R as internal primers. DNA amplification products of about 380 bp compatible with Paracoccidioides spp. were detected in six samples (10%), being sequenced and identified as P. brasiliensis. These findings indicate that the soils of the Acre state could be considered a potential source for Paracoccidioides spp., suggesting that local infections are likely.
Assuntos
Paracoccidioides , Paracoccidioidomicose , Animais , Humanos , Paracoccidioides/genética , Microbiologia do Solo , Fungos , Solo , Paracoccidioidomicose/epidemiologia , Paracoccidioidomicose/microbiologia , Brasil/epidemiologiaRESUMO
Agaricomycetes are highlighted for producing a variety of compounds and enzymes with nutritional and medicinal properties. However, the knowledge of the diversity of this group of fungi is still insufficient, as well as their biological and enzymatic activities. Thus, the objective of this work is to describe the occurrence, biological and enzymatic activities of Agaricomycetes from the Brazilian Amazon. The present study is a systematic review with the literature search done in the following databases: Scielo, Google Scholar, PubMed and ScienceDirect. The descriptors used were Basidiomycota, Agaricomycetes, mushroom, antimicrobial activity, antitumor activity, antioxidant activity, anti-inflammatory activity, immunomodulator, enzymatic activity, and Brazilian Amazon. We used as inclusion criteria articles in Portuguese and English, published between 2010 and 2021 and that had the full text available and presented relevance to the exposed topic, and as exclusion criteria, works not done in the Brazilian Amazon, duplicate articles in the databases search or outside the topic under study. A total of 40 articles, published between 2010 and 2021, were selected for analysis. 230 species of Agaricomycetes fungi were described for the Brazilian Amazon, with the most frequent orders being Polyporales (52.60%), Agaricales (14.35%), and Hymenochaetales (13.91%). Six studies were found on antimicrobial activity for promising Agaricomycete fungi against the bacteria Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus and the fungi Candida albicans, C. parapsilosis and C. tropicalis. For the antioxidant activity, a study described the species Lentinus citrinus with high amounts of antioxidant compounds. For enzymatic activity, five studies reported Agaricomycete fungi producing protease, cellulase, amylase, pectinase, laccase, and xylanase enzymes. This review shows the scarcity of studies on the description and technological potential of Agaricomycetes from the Brazilian Amazon, highlighting the need to encourage the study of this group of organisms.
Assuntos
Agaricales , Anti-Infecciosos , Basidiomycota , Brasil , Antioxidantes/farmacologiaRESUMO
PURPOSE: Surgical oncologists are frequently confronted with the question of expected long-term prognosis. The aim of this study was to apply machine learning algorithms to optimize survival prediction after oncological resection of gastroesophageal cancers. METHODS: Eligible patients underwent oncological resection of gastric or distal esophageal cancer between 2001 and 2020 at Heidelberg University Hospital, Department of General Surgery. Machine learning methods such as multi-task logistic regression and survival forests were compared with usual algorithms to establish an individual estimation. RESULTS: The study included 117 variables with a total of 1360 patients. The overall missingness was 1.3%. Out of eight machine learning algorithms, the random survival forest (RSF) performed best with a concordance index of 0.736 and an integrated Brier score of 0.166. The RSF demonstrated a mean area under the curve (AUC) of 0.814 over a time period of 10 years after diagnosis. The most important long-term outcome predictor was lymph node ratio with a mean AUC of 0.730. A numeric risk score was calculated by the RSF for each patient and three risk groups were defined accordingly. Median survival time was 18.8 months in the high-risk group, 44.6 months in the medium-risk group and above 10 years in the low-risk group. CONCLUSION: The results of this study suggest that RSF is most appropriate to accurately answer the question of long-term prognosis. Furthermore, we could establish a compact risk score model with 20 input parameters and thus provide a clinical tool to improve prediction of oncological outcome after upper gastrointestinal surgery.
Assuntos
Algoritmos , Neoplasias Esofágicas , Humanos , Prognóstico , Fatores de Risco , Aprendizado de Máquina , Neoplasias Esofágicas/cirurgiaRESUMO
Biochemical responses inherent to antioxidant systems as well morphological and anatomical properties of photomorphogenic, hormonal and developmental tomato mutants were investigated. Compared to the non-mutant Micro-Tom (MT), we observed that the malondialdehyde (MDA) content was enhanced in the diageotropica (dgt) and lutescent (l) mutants, whilst the highest levels of hydrogen peroxide (H(2)O(2)) were observed in high pigment 1 (hp1) and aurea (au) mutants. The analyses of antioxidant enzymes revealed that all mutants exhibited reduced catalase (CAT) activity when compared to MT. Guaiacol peroxidase (GPOX) was enhanced in both sitiens (sit) and notabilis (not) mutants, whereas in not mutant there was an increase in ascorbate peroxidase (APX). Based on PAGE analysis, the activities of glutathione reductase (GR) isoforms III, IV, V and VI were increased in l leaves, while the activity of superoxide dismutase (SOD) isoform III was reduced in leaves of sit, epi, Never ripe (Nr) and green flesh (gf) mutants. Microscopic analyses revealed that hp1 and au showed an increase in leaf intercellular spaces, whereas sit exhibited a decrease. The au and hp1 mutants also exhibited a decreased in the number of leaf trichomes. The characterization of these mutants is essential for their future use in plant development and ecophysiology studies, such as abiotic and biotic stresses on the oxidative metabolism.
Assuntos
Antioxidantes/metabolismo , Oxirredutases/genética , Solanum lycopersicum/genética , Eletroforese em Gel de Poliacrilamida , Solanum lycopersicum/enzimologia , Solanum lycopersicum/ultraestrutura , Microscopia Eletrônica de Varredura , Oxirredutases/metabolismo , Estresse Fisiológico/genéticaRESUMO
This study aimed to examine the antibacterial activity of extracts of Amazonian Agaricomycetes macrofungi. The sample comprised 168 specimen collected at the Zoobotanical Park of the Federal University of Acre (Brazil), of which 32 (19%) were isolated. Extracts of the 32 isolates and 28 Agaricomycetes basidiomata were prepared and tested for activity against Staphylococcus aureus, Streptococcus pneumoniae, Escherichia coli, and Klebsiella pneumoniae bacteria, using the disc diffusion method. Of the 32 metabolite extracts of the isolated Basidiomycetes, 11 (34.4%) exhibited antibacterial activity especially against Gram-negative E. coli and K. pneumoniae bacteria, while of the 28 basidiomata extracts, 6 (21.4%) exhibited antibacterial activity mainly against the Gram-positive S. aureus bacteria. This study is the first to report the antibacterial activity of the Agaricomycetes species Coriolopsis caperata, Cyclomyces iodinus, Cymatoderma sp., Favolus tenuiculus, and Tyromyces cf. polyporoides, and contributes as the first investigation about the antibacterial potential of Basidiomycetes grown in Southwest Amazonia.
Assuntos
Agaricales/química , Antibacterianos/farmacologia , Basidiomycota/química , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Polyporales/química , Agaricales/classificação , Antibacterianos/isolamento & purificação , Basidiomycota/classificação , Brasil , Escherichia coli/efeitos dos fármacos , Klebsiella pneumoniae/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Polyporaceae/química , Staphylococcus aureus/efeitos dos fármacos , Streptococcus pneumoniae/efeitos dos fármacosRESUMO
ABSTRACT Termites of the Nasutitermes genus are considered one of the main urban and agroforestry pests in Brazil, where the main method of control is the application of pesticides. The uso of entomopathogenic fungi to reduce the population of this plague in the environment could be use as an alternative. The goal of this study was to evaluate the virulence of isolates native Amazonian fungi belonging to the Tolypocladium endophyticum, Metarhizium anisopliae and Metarhizium marquandii species for the control of Nasutitermes sp. The strains of T. endophyticum (4.439), M. anisopliae (4.443) and M. marquandii (4.472) with their respective isolation codes, were evaluated using suspensions at concentrations of 105, 106, 107 and 108 conidia/mL against the termites. The fungi were characterized to species level by molecular analysis. The greatest virulence was registered with T. endophyticum (4.439), with a mortality of 100 % on the 4th day of treatment for all analyzed concentrations. The M. anisopliae strain (4.443) proved to be efficient, causing a mortality of 100 % on the 7th and 6th days at dilutions of 107 and 108 conidia/mL, respectively. Rates lower than 100 % were registered with M. marquandii (4.472). Therefore, the three fungal strains showed virulence against the termites Nasutitermes sp. In this study, the fungi Tolypocladium endophyticum and Metarhizium marquandii are reported for the first time for the biological control of pests, indicating the potential of native Amazonian fungi for the biological control of thermites Nasutitermes sp.
RESUMEN Las termitas del género Nasutitermes son consideradas una de las principales plagas urbanas y agroforestales de Brasil, donde el principal método de control es la aplicación de pesticidas. Los hongos entomopatógenos pueden ser usados como alternativa para reducir la población de esta plaga en el medio ambiente. Por tanto, el objetivo de este estudio fue evaluar la virulencia de aislados de hongos nativos de suelo amazónico pertenecientes a las especies Tolypocladium endophyticum, Metarhizium anisopliae y Metarhizium marquandii para el control de Nasutitermes sp. Las cepas de T. endophyticum (4,439), M. anisopliae (4,443) y M. marquandii (4,472) con sus respectivos códigos de aislamiento, fueron evaluadas utilizando suspensiones a concentraciones de 105, 106, 107 y 108 conidios/mL contra las termitas. Los hongos se caracterizaron mediante análisis moleculares para confirmar la especie. La mayor virulencia se registró con el hongo T. endophyticum (4,439), con una mortalidad del 100 % al cuarto día de tratamiento para todas las concentraciones analizadas. La cepa M. anisopliae (4,443) demostró ser eficiente, causando una mortalidad del 100 % al sexto y septimo días a las diluciones de 107 y 108 conidios / mL, respectivamente. Se registraron tasas inferiores al 100 % con M. marquandii (4,472). Por tanto, las tres cepas de hongos mostraron virulencia contra las termitas Nasutitermes sp. En este estudio, los hongos Tolypocladium endophyticum y Metarhizium marquandii son reportados por primera vez para el control biológico de plagas, indicando el potencial de hongos nativos de suelo amazónico para el control biológico de termitas Nasutitermes sp.
RESUMO
Sugarcane smut disease, caused by the biotrophic fungus Sporisorium scitamineum, is characterized by the development of a whip-like structure from the plant meristem. The disease causes negative effects on sucrose accumulation, fiber content and juice quality. The aim of this study was to exam whether the transcriptomic changes already described during the infection of sugarcane by S. scitamineum result in changes at the metabolomic level. To address this question, an analysis was conducted during the initial stage of the interaction and through disease progression in a susceptible sugarcane genotype. GC-TOF-MS allowed the identification of 73 primary metabolites. A set of these compounds was quantitatively altered at each analyzed point as compared with healthy plants. The results revealed that energetic pathways and amino acid pools were affected throughout the interaction. Raffinose levels increased shortly after infection but decreased remarkably after whip emission. Changes related to cell wall biosynthesis were characteristic of disease progression and suggested a loosening of its structure to allow whip growth. Lignin biosynthesis related to whip formation may rely on Tyr metabolism through the overexpression of a bifunctional PTAL. The altered levels of Met residues along with overexpression of SAM synthetase and ACC synthase genes suggested a role for ethylene in whip emission. Moreover, unique secondary metabolites antifungal-related were identified using LC-ESI-MS approach, which may have potential biomarker applications. Lastly, a putative toxin was the most important fungal metabolite identified whose role during infection remains to be established.
RESUMO
Sugarcane smut disease is caused by the biotrophic fungus Sporisorium scitamineum. The disease is characterized by the development of a whip-like structure from the primary meristems, where billions of teliospores are produced. Sugarcane smut also causes tillering and low sucrose and high fiber contents, reducing cane productivity. We investigated the biological events contributing to disease symptoms in a smut intermediate-resistant sugarcane genotype by examining the transcriptional profiles (RNAseq) shortly after inoculating the plants and immediately after whip emission. The overall picture of disease progression suggests that premature transcriptional reprogramming of the shoot meristem functions continues until the emergence of the whip. The guidance of this altered pattern is potentially primarily related to auxin mobilization in addition to the involvement of other hormonal imbalances. The consequences associated with whip emission are the modulation of typical meristematic functions toward reproductive organ differentiation, requiring strong changes in carbon partitioning and energy production. These changes include the overexpression of genes coding for invertases and trehalose-6P synthase, as well as other enzymes from key metabolic pathways, such as from lignin biosynthesis. This is the first report describing changes in the transcriptional profiles following whip development, providing a hypothetical model and candidate genes to further study sugarcane smut disease progression.
Assuntos
Perfilação da Expressão Gênica , Doenças das Plantas/microbiologia , Saccharum/microbiologia , Análise de Sequência de RNA/métodos , Transcrição Gênica , Ustilaginales/patogenicidade , Saccharum/genéticaRESUMO
Sporisorium scitamineum is a biotrophic fungus responsible for the sugarcane smut, a worldwide spread disease. This study provides the complete sequence of individual chromosomes of S. scitamineum from telomere to telomere achieved by a combination of PacBio long reads and Illumina short reads sequence data, as well as a draft sequence of a second fungal strain. Comparative analysis to previous available sequences of another strain detected few polymorphisms among the three genomes. The novel complete sequence described herein allowed us to identify and annotate extended subtelomeric regions, repetitive elements and the mitochondrial DNA sequence. The genome comprises 19,979,571 bases, 6,677 genes encoding proteins, 111 tRNAs and 3 assembled copies of rDNA, out of our estimated number of copies as 130. Chromosomal reorganizations were detected when comparing to sequences of S. reilianum, the closest smut relative, potentially influenced by repeats of transposable elements. Repetitive elements may have also directed the linkage of the two mating-type loci. The fungal transcriptome profiling from in vitro and from interaction with sugarcane at two time points (early infection and whip emergence) revealed that 13.5% of the genes were differentially expressed in planta and particular to each developmental stage. Among them are plant cell wall degrading enzymes, proteases, lipases, chitin modification and lignin degradation enzymes, sugar transporters and transcriptional factors. The fungus also modulates transcription of genes related to surviving against reactive oxygen species and other toxic metabolites produced by the plant. Previously described effectors in smut/plant interactions were detected but some new candidates are proposed. Ten genomic islands harboring some of the candidate genes unique to S. scitamineum were expressed only in planta. RNAseq data was also used to reassure gene predictions.
Assuntos
Genoma Fúngico , Interações Hospedeiro-Patógeno/genética , Transcriptoma , Ustilaginales/genética , Sequência de Aminoácidos , Sequência de Bases , Dados de Sequência Molecular , Fases de Leitura Aberta , Saccharum/microbiologia , Ustilaginales/patogenicidade , Virulência/genéticaRESUMO
The herbicides ametryn and clomazone are widely used in sugarcane cultivation, and following microbial degradation are considered as soil and water contaminants. The exposure of microorganisms to pesticides can result in oxidative damage due to an increase in the production of reactive oxygen species (ROS). This study investigated the response of the antioxidant systems of two bacterial strains tolerant to the herbicides ametryn and clomazone. Bacteria were isolated from soil with a long history of ametryn and clomazone application. Comparative analyses based on 16S rRNA gene sequences revealed that strain CC07 is phylogenetically related to Pseudomonas aeruginosa and strain 4C07 to P. fulva. The two bacterial strains were grown for 14 h in the presence of separate and combined herbicides. Lipid peroxidation, reduced glutathione content (GSH) and antioxidant enzymes activities were evaluated. The overall results indicated that strain 4C07 formed an efficient mechanism to maintain the cellular redox balance by producing reactive oxygen species (ROS) and subsequently scavenging ROS in the presence of the herbicides. The growth of bacterium strain 4C07 was inhibited in the presence of clomazone alone, or in combination with ametryn, but increased glutathione reductase (GR) and glutathione S-transferase (GST) activities, and a higher GSH concentration were detected. Meanwhile, reduced superoxide dismutase (SOD), catalase (CAT) and GST activities and a lower concentration of GSH were detected in the bacterium strain CC07, which was able to achieve better growth in the presence of the herbicides. The results suggest that the two bacterial strains tolerate the ametryn and clomazone herbicides with distinctly different responses of the antioxidant systems.
Assuntos
Herbicidas/metabolismo , Isoxazóis/metabolismo , Oxazolidinonas/metabolismo , Pseudomonas/efeitos dos fármacos , Pseudomonas/enzimologia , Microbiologia do Solo , Poluentes do Solo/metabolismo , Triazinas/metabolismo , Antioxidantes/metabolismo , Catalase/metabolismo , Glutationa/metabolismo , Glutationa Peroxidase/metabolismo , Glutationa Redutase/metabolismo , Glutationa Transferase/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Filogenia , Pseudomonas/genética , Pseudomonas/metabolismo , RNA Ribossômico 16S/genética , Espécies Reativas de Oxigênio/metabolismo , Superóxido Dismutase/metabolismoRESUMO
Seed priming with hormones has been an efficient method for increasing seed vigor as well as seedling growth under stressful conditions. These responses have in the past been attributed to the activation of antioxidant systems in a range of crops. The results described in this work show that hormonal priming with methyl jasmonate, salicylic acid or CEPA (chloroethylphosphonic acid), an ethylene (ET) releaser, does not induce the antioxidant activity of superoxide dismutase, catalase, ascorbate peroxidase or glutathione reductase in maize seedlings subjected to salt stress. The enhanced biomass of maize seedlings under salt stress that was observed only from ET priming indicates that the stress tolerance in maize from ethylene priming is a fundamental process for stress tolerance acquisition, which is explained, however, by other biochemical mechanisms but not by changes in the antioxidant system.
RESUMO
Seed priming with hormones has been an efficient method for increasing seed vigor as well as seedling growth under stressful conditions. These responses have in the past been attributed to the activation of antioxidant systems in a range of crops. The results described in this work show that hormonal priming with methyl jasmonate, salicylic acid or CEPA (chloroethylphosphonic acid), an ethylene (ET) releaser, does not induce the antioxidant activity of superoxide dismutase, catalase, ascorbate peroxidase or glutathione reductase in maize seedlings subjected to salt stress. The enhanced biomass of maize seedlings under salt stress that was observed only from ET priming indicates that the stress tolerance in maize from ethylene priming is a fundamental process for stress tolerance acquisition, which is explained, however, by other biochemical mechanisms but not by changes in the antioxidant system.
RESUMO
O objetivo deste estudo foi analisar a forma de organização de uma atividade em pequenos grupos, a partir das significações produzidas/veiculadas no contexto de aulas de Educação Física. Foram utilizadas como ferramentas metodológicas a videografia e a análise microgenética, ambas pautadas nos aportes da perspectiva histórico-cultural. A atividade analisada constitui-se da elaboração de um jogo desenvolvido por um grupo de alunos. Na apreensão do fluxo das interações, evidenciou-se um movimento de disputa entre os membros do grupo pelo direito de voz, na tentativa de ocupar um lugar social de destaque diante dos demais, episódio em que houve pouca mediação por parte da professora. Assim, constatou-se que a atividade em pequenos grupos é um importante espaço de interação entre os sujeitos que dela participaram e como locus de produção de significações, pela possibilidade de confrontos/oposições/alianças de pontos de vista entre esses sujeitos.
The objective of this study was to analyze the organization of an activity within small groups, starting from significations obtained within the context of physical education lessons. As tools of methodology, videography and micro-genetic analysis were employed, both utilized from a cultural-historical perspective. The activity under analysis was the development of a game, on part of a group of students. From the flow of interaction, it became evident that an element of vocal competition had arisen among the group members, in an attempt to occupy a position of prominence over the others, an event that lead to a little mediation on part of the teacher. Therefore, it can be seen that the activity performed in small groups is an important realm of interaction, where participating members act as locus of production of significations, through the possibility of alliances, confrontation and opposition of ideas between participating subjects.
El objetivo de este estudio fue analizar la forma de organización de una actividad en pequeños grupos, a partir de las significaciones producidas / difundidas en el contexto de clases de Educación Física. Se utilizaron como herramientas metodológicas la videografía y el análisis micro genético, ambos pautados en los aportes de la perspectiva histórico-cultural. La actividad analizada se constituyó de la elaboración de un juego desarrollado por un grupo de alumnos. En la aprehensión del flujo de las interacciones, se evidenció un movimiento de disputa entre los miembros del grupo por el derecho de voz, en el intento de ocupar un lugar social de destaque delante de los demás, episodio en el que hubo poca mediación por parte de la profesora. Así, se constató que la actividad en pequeños grupos es un importante espacio de interacción entre los sujetos que de ella participaron y como locus de producción de significaciones, por la posibilidad de confrontes /oposiciones /alianzas de puntos de vista entre esos sujetos.
Assuntos
Educação Física e Treinamento , Grupos de PesquisaRESUMO
O objetivo deste estudo foi analisar a forma de organização de uma atividade em pequenos grupos, a partir das significações produzidas/veiculadas no contexto de aulas de Educação Física. Foram utilizadas como ferramentas metodológicas a videografia e a análise microgenética, ambas pautadas nos aportes da perspectiva histórico-cultural. A atividade analisada constitui-se da elaboração de um jogo desenvolvido por um grupo de alunos. Na apreensão do fluxo das interações, evidenciou-se um movimento de disputa entre os membros do grupo pelo direito de voz, na tentativa de ocupar um lugar social de destaque diante dos demais, episódio em que houve pouca mediação por parte da professora. Assim, constatou-se que a atividade em pequenos grupos é um importante espaço de interação entre os sujeitos que dela participaram e como locus de produção de significações, pela possibilidade de confrontos/oposições/alianças de pontos de vista entre esses sujeitos(AU)
Assuntos
Grupos de Pesquisa , Educação Física e TreinamentoRESUMO
Esta dissertação teve como objetivo analisar a forma de organização de uma atividade em pequenos grupos no contexto de aulas de Educação Física e seus desdobramentos no que se refere ao desenvolvimento da atividade e às relações interpessoais dali decorrentes. Pautadas na perspectiva histórico-cultural, foram tomadas como unidade de análise as significações veiculadas e produzidas no decurso dessa atividade pelos sujeitos compostos por uma professora de Educação Física e uma de suas turmas do ensino fundamental de uma escola municipal. Intencionando captar nuances da trama dialógica configurada pelas falas e expressões gestuais dos sujeitos em relação, foi utilizado como procedimento para a coleta de dados o uso de filmagens em VHS (videografia) e para a sua análise, a técnica de análise de episódios (Smolka, 1991). Para tanto, a professora dividiu a turma em grupos, e organizou a atividade que posteriormente foi analisada em quatro momentos: elaboração, apresentação, execução e avaliação de um jogo, sendo que as análises da presente pesquisa se centraram no movimento de um dos grupos. Mais do que conclusões, este estudo pretendeu explicitar processos, portanto, a partir dos dados analisados, foi possível apreender o fluxo de interações e significações propiciadas pelo desenvolvimento da atividade e pelas intervenções da professora (AU)