RESUMO
Salinity is harmful to crops when the concentration of soluble salts overcomes the salinity threshold of the crop, causing osmotic stress and limitations in plant growth. In this scenario, adopting tolerant cultivars is the most adequate strategy to minimize agricultural losses. However, the inheritance of tolerance depends on the genotype. From this perspective, this study assessed the tolerance to severe salt stress in 11 cotton cultivars based on gas exchange parameters and the free proline content. The cultivars were grown in a greenhouse and subjected to 34 days of saline irrigation (10 dS m-1), starting 45 days after seedling emergence (B1 phase). Plant growth was monitored weekly until the end of the salt stress period. The treatments consisted of a combination of two factors: eleven cultivars associated with two electrical conductivity levels of irrigation water (ECw: 0.3 and 10.0 dS m-1). The experimental design was in randomized blocks in a 11 × 2 factorial arrangement with three replications (66 plots), with the experimental unit consisting of one plant per plot. Salinity impacted plant growth, being reflected on the gas exchange and free proline data of most cultivars. However, BRS 286, FMT 705, BRS 416, and BRS Acácia, and CNPA 7MH withstood the effects of stress and osmotically adjusted to the salt stress conditions, thus minimizing the damage to growth. Those cultivars are the most indicated for improvement programs aiming at tolerance to salt stress based on the results found in this research.
Assuntos
Estresse Salino , Tolerância ao Sal , Plântula , Salinidade , ProlinaRESUMO
The transient receptor potential ankyrin 1 (TRPA1) is expressed in peripheral and spinal terminals of sensory neurons, jointly to the vanilloid receptor (TRPV1). A relevant peripheral role of TRPA1 receptor has been implicated in a variety of processes, including the detection of noxious cold, and diverse painful stimulus, but the functional role of TRPA1 receptor in nociceptive transmission at spinal cord in vivo is poorly known. Therefore, the aim of this study was to evaluate whether the glutamatergic system is involved in the transmission of nociceptive stimulus induced for a TRPA1 agonist in the rat spinal cord. We observed that cinnamaldehyde, a TRPA1 agonist, on spinal cord synaptosomes leads to an increase in [Ca(2+)](i) and a rapid release of glutamate, but was not able to change the specific [(3)H]-glutamate binding. In addition, spinally administered cinnamaldehyde produced heat hyperalgesia and mechanical allodynia in rats. This behavior was reduced by the co-injection (i.t.) of camphor (TRPA1 antagonist) or MK-801 (N-methyl-D-aspartate (NMDA) receptor antagonist) to cinnamaldehyde. Besides, the pretreatment with resiniferatoxin (RTX), a potent TRPV1 agonist, abolished the cinnamaldehyde-induced heat hyperalgesia. Here, we showed that intrathecal RTX results in a decrease in TRPA1 and TRPV1 immunoreactivity in dorsal root ganglion. Collectively, our results demonstrate the pertinent participation of spinal TRPA1 in the possible enhancement of glutamatergic transmission of nociceptive signals leading to increase of the hypersensitivity, here observed as heat hyperalgesia. Then the modulation of spinal TRPA1 might be a valuable target in painful conditions associated with central pain hypersensitivity.
Assuntos
Ácido Glutâmico/fisiologia , Nociceptividade/efeitos dos fármacos , Canais de Cátion TRPC/agonistas , Acroleína/análogos & derivados , Animais , Cálcio/metabolismo , Antagonistas de Aminoácidos Excitatórios/farmacologia , Ácido Glutâmico/metabolismo , Temperatura Alta , Técnicas In Vitro , Injeções Espinhais , Masculino , Membranas/efeitos dos fármacos , Membranas/metabolismo , N-Metilaspartato/metabolismo , Medição da Dor/efeitos dos fármacos , Estimulação Física , Ratos , Ratos Wistar , Medula Espinal/efeitos dos fármacos , Transmissão Sináptica/efeitos dos fármacos , Sinaptossomos/efeitos dos fármacos , Sinaptossomos/metabolismo , Canal de Cátion TRPA1 , Canais de Cátion TRPV/agonistas , Canais de Cátion TRPV/antagonistas & inibidoresRESUMO
The sorghum crop has grown rapidly in recent years, for being a plant with xerophilous characteristics; its production has especially increased in Northeastern Brazil due to its ability to withstand dry environments. Weeds are a major problem for grain crops, as these can significantly reduce yield, particularly when they emerge in the early stages of crops. To obtain crops resistant to weeds, studies have been conducted to demonstrate that some plants have a natural defense consisting in an organism's ability to produce metabolites that act to either inhibit or stimulate growth and development of other organisms grown in the same environment, which is called allelopathy. Sorghum is one of the plants that possess proven allelopathy, producing a set of lipid complex substances and proteins generically called sorgoleone, having as its main compound 2-hydroxy-5-methoxy-3-[(Z,Z)-8',11',14'-pentadecatriene]-p-benzoquinone, which is naturally released into the soil from their roots and trichomes, inhibiting the growth of weeds upon contact with them. Because of these inherent characteristics of the sorghum crop, the present work aims to discuss the possible benefits of using this cereal, due to its allelopathic effects, as well as to inform about the known mechanisms of production and action of the main constituent compounds of sorgoleone and other compounds produced by the plant's roots.
A cultura do sorgo cresceu rapidamente nestes últimos anos, por ser uma planta com características xerófilas, apresentando um aumento de sua produção principalmente na região nordeste devido a sua capacidade de suportar ambientes de cultivo mais secos. As ervas daninhas são um grande problema para os cultivares, pois estas podem reduzir significativamente a produção de grãos, particularmente quando surgem nas fases iniciais das culturas. Visando a obtenção de culturas resistentes às ervas daninhas, estudos têm sido realizados demonstrando que algumas plantas possuem uma defesa natural que consiste na capacidade de um organismo produzir metabólitos que atuam inibindo ou o crescimento ou o desenvolvimento de outros organismos que estão próximos; a esta capacidade dá-se o nome de alelopatia. O sorgo é uma das plantas que possuem sua alelopatia comprovada, produzindo um complexo de substâncias lipídicas e proteínas denominados genericamente de sorgoleone, tendo como seu principal composto o 2-hidroxi-5-metoxi-3-[(Z,Z)-8',11',14'-pentadecatrieno]-p-benzoquinona, que é naturalmente liberado para o solo a partir dos tricomas das suas raízes e, no momento em que entram em contato com as ervas daninhas, inibem seu crescimento. Devido a tais características inerentes à cultura do sorgo, este trabalho tem como objetivo discorrer sobre os possíveis benefícios do uso desse cereal devido a sua comprovada alelopatia, bem como informar os conhecidos mecanismos de produção e atuação dos principais compostos constituintes do sorgoleone produzidos pelas suas raízes.
RESUMO
The sorghum crop has grown rapidly in recent years, for being a plant with xerophilous characteristics; its production has especially increased in Northeastern Brazil due to its ability to withstand dry environments. Weeds are a major problem for grain crops, as these can significantly reduce yield, particularly when they emerge in the early stages of crops. To obtain crops resistant to weeds, studies have been conducted to demonstrate that some plants have a natural defense consisting in an organism's ability to produce metabolites that act to either inhibit or stimulate growth and development of other organisms grown in the same environment, which is called allelopathy. Sorghum is one of the plants that possess proven allelopathy, producing a set of lipid complex substances and proteins generically called sorgoleone, having as its main compound 2-hydroxy-5-methoxy-3-[(Z,Z)-8',11',14'-pentadecatriene]-p-benzoquinone, which is naturally released into the soil from their roots and trichomes, inhibiting the growth of weeds upon contact with them. Because of these inherent characteristics of the sorghum crop, the present work aims to discuss the possible benefits of using this cereal, due to its allelopathic effects, as well as to inform about the known mechanisms of production and action of the main constituent compounds of sorgoleone and other compounds produced by the plant's roots.
A cultura do sorgo cresceu rapidamente nestes últimos anos, por ser uma planta com características xerófilas, apresentando um aumento de sua produção principalmente na região nordeste devido a sua capacidade de suportar ambientes de cultivo mais secos. As ervas daninhas são um grande problema para os cultivares, pois estas podem reduzir significativamente a produção de grãos, particularmente quando surgem nas fases iniciais das culturas. Visando a obtenção de culturas resistentes às ervas daninhas, estudos têm sido realizados demonstrando que algumas plantas possuem uma defesa natural que consiste na capacidade de um organismo produzir metabólitos que atuam inibindo ou o crescimento ou o desenvolvimento de outros organismos que estão próximos; a esta capacidade dá-se o nome de alelopatia. O sorgo é uma das plantas que possuem sua alelopatia comprovada, produzindo um complexo de substâncias lipídicas e proteínas denominados genericamente de sorgoleone, tendo como seu principal composto o 2-hidroxi-5-metoxi-3-[(Z,Z)-8',11',14'-pentadecatrieno]-p-benzoquinona, que é naturalmente liberado para o solo a partir dos tricomas das suas raízes e, no momento em que entram em contato com as ervas daninhas, inibem seu crescimento. Devido a tais características inerentes à cultura do sorgo, este trabalho tem como objetivo discorrer sobre os possíveis benefícios do uso desse cereal devido a sua comprovada alelopatia, bem como informar os conhecidos mecanismos de produção e atuação dos principais compostos constituintes do sorgoleone produzidos pelas suas raízes.
RESUMO
Brain damage from neonatal hypoxia-ischemia (HI) plays a major role in neonatal mortality and morbidity. Using the Rice-Vannucci model of HI in rats, we verified that 8 days after HI injury, adenosine deaminase (ADA), N-acetyl-glucosaminidase (NAG) and myeloperoxidase (MPO) activities increased in the left hemisphere hippocampus (HI group); however, the activity of 5'-nucleotidase (5'NT) remained unchanged. In the hematoxylin-eosin analysis (HE), we detected selective and delayed degeneration of hippocampal pyramidal neurons and astroglial reaction accompanied by glial fibrillary acidic protein (GFAP)-positive and vimentin-positive in the immunohistochemistry analysis in the HI group compared with the control group. We observed the selective necrosis of neurons, vascular endothelial proliferation and inflammatory response accompanied by the increase of the key enzyme of adenosine metabolism in the HI group. The increase of ADA activity, despite the 5'NT activity was not altered, indicates the predominance of ADA activity in the postischemic homeostasis of extra cellular adenosine. The presence of leukocytes into the ischemic areas displays the possible importance of the neutrophil-macrophages associated with the increase of MPO and NAG activities 8 days after HI. These findings may contribute to the evaluation of some consequences of the damage caused by neonatal HI.
Assuntos
Hipocampo/enzimologia , Hipocampo/patologia , Hipóxia-Isquemia Encefálica/metabolismo , Hipóxia-Isquemia Encefálica/patologia , Animais , Animais Recém-Nascidos , Astrócitos/metabolismo , Astrócitos/patologia , Hexosaminidases/metabolismo , Hipocampo/lesões , Hipóxia-Isquemia Encefálica/imunologia , Imuno-Histoquímica , Inflamação/metabolismo , Inflamação/patologia , Masculino , Neurônios/metabolismo , Neurônios/patologia , Peroxidase/metabolismo , Ratos , Ratos WistarRESUMO
Chromosome numbers in Cyperaceae lower than the typical basic number x = 5 have been described for only three species: Rhynchospora tenuis (n = 2), Fimbristylis umbellaris (n = 3) and Eleocharis subarticulata (n = 3). Eleocharis maculosa is recorded here as the fourth species of Cyperaceae that has a chromosome number lower than 2n = 10, with 2n = 8, 7 and 6. The karyotype differentiation in E. maculosa was studied using conventional staining (mitosis and meiosis), FISH with 45S and 5S rDNA and telomere probes. The results allow us to determine which chromosomes of the chromosome race with 2n = 10 fused to form the remaining reduced numbers, as well as to understand how the symploidy and translocation mechanisms were important in karyotype differentiation and the formation of chromosome races in Eleocharis.
Assuntos
Cromossomos de Plantas/genética , Eleocharis/genética , DNA Ribossômico/genética , Eleocharis/crescimento & desenvolvimento , Hibridização in Situ Fluorescente , Cariotipagem , Meiose/genéticaRESUMO
Extending a model due to Derrida, Gardner, and Zippelius, we have studied the recognition ability of an extreme and asymmetrically diluted version of the Hopfield model for associative memory by including the effect of a stimulus in the dynamics of the system. We obtain exact results for the dynamic evolution of the average network superposition. The stimulus field was considered as proportional to the overlapping of the state of the system with a particular stimulated pattern. Two situations were analyzed, namely, the external stimulus acting on the initialization pattern (parallel stimulus) and the external stimulus acting on a pattern orthogonal to the initialization one (orthogonal stimulus). In both cases, we obtained the complete phase diagram in the parameter space composed of the stimulus field, thermal noise, and network capacity. Our results show that the system improves its recognition ability for parallel stimulus. For orthogonal stimulus two recognition phases emerge with the system locking at the initialization or stimulated pattern. We confront our analytical results with numerical simulations for the noiseless case T = 0.
Assuntos
Potenciais de Ação/fisiologia , Estimulação Elétrica , Modelos Neurológicos , Rede Nervosa/fisiologia , Transmissão Sináptica/fisiologia , Animais , Simulação por Computador , HumanosRESUMO
We investigate the scale invariance of the average ratio between the masses of the largest and second largest clusters at percolation. We employ a finite size scaling method to estimate percolation thresholds based on the simulations of relatively small lattices, and report on estimates for p(c) in hypercubic lattices with d=2-7, in full agreement with the best literature estimates. Also, we find the critical mass ratio to be strongly dependent on the boundary conditions, decreasing with the lattice dimension. Further, we compute several relevant mass distribution functions associated with the two largest clusters, which approach to limiting distributions for d>6. Finally, we discuss the main relevant features of the mass distributions in light of the relative role played by the spanning and nonspanning clusters.