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Glyphosate Effects on Sugarcane Metabolism and Growth  [PDF]
Caio Antonio Carbonari, Giovanna Larissa Gimenes Cotrick Gomes, Edivaldo Domingues Velini, Renato Fernandes Machado, Plinio Saulo Sim?es, Gabrielle de Castro Macedo
American Journal of Plant Sciences (AJPS) , 2014, DOI: 10.4236/ajps.2014.524374
Abstract: Glyphosate is the most widely used herbicide in the world. In sugarcane, it is used as a herbicide when applied at its field rate, but it is also used as ripener when applied as low doses. However, the effects of glyphosate on plant metabolism and sugarcane growth are not fully understood. This study aimed to evaluate the metabolic changes and the effects on sugarcane plant growth caused by the application of different doses of glyphosate. Sugarcane plants were grown in a greenhouse and subjected to glyphosate applications at doses of 7.2; 18; 36; 72; 180; 360 and 720 g a.e. ha-1. Plants grown without an herbicide application were used as a control. Plants from each treatment were collected at 2, 7, 14, and 21 days after treatment (DAT) application to quantify the levels of shikimic acid, quinic acid, shikimate-3-phosphate, glyphosate, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), phenylalanine, tyrosine, and tryptophan. Visual evaluations of plant intoxication were performed at the same time as the collection of plants, and the quantification of their shoot dry biomass was performed at 21 DAT. At doses of glyphosate greater than 72 g a.e. ha-1, increases in the levels of shikimic acid, quinic acid, and shikimate-3-phosphate occurred and AMPA was detected in the plants. Initially, glyphosate caused increases in the plant levels of phenylalanine and tyrosine at doses of 72 and 180 g a.e. ha-1, although a decrease in the levels of aromatic amino acids subsequently occurred at and above the doses of 72 or 180 g a.e. ha-1. The doses ranging from 7.2 to 36 g a.e. ha-1 promoted an increase in plant shoot biomass, and doses greater than 72 g a.e. ha-1 caused significant reductions in dry mass.
Resíduos de glifosato e ácido aminometilfosf?nico e teores de isoflavonas em soja BRS 244 RR e BRS 154
Bohm, Giani Mariza B?rwald;Genovese, Maria Inés;Pigosso, Gustavo;Trichez, Daniel;Rombaldi, Cesar Valmor;
Ciência e Tecnologia de Alimentos , 2008, DOI: 10.1590/S0101-20612008000500030
Abstract: the use of glyphosate is the best way to control weed growing when cultivating genetically modified soybean (gmrr) brs 244 rr. however, there have been doubts about the safety of this herbicide use concerning its effects on the quality of grains and on the soil of albaqualf cultivated gmrr soybean. glyphosate and the metabolite aminomethylphosphonic acid (ampa) residues can be present in the grains and affect the isoflavones concentration. therefore, brs 244 rr and brs 154 soybeans with the following cultivated treatments were evaluated: t1 - soybean brs 244 rr, without herbicide and hand-weeded at 28 days after planting (dap); t2 - soybean brs 154, without herbicide and hand-weeded at 28 dap; t3 - soybean brs 244 rr with one application of 960 g ai ha-1 of glyphosate at 28 dap; t4 - soybean brs 244 rr, with two applications of 960 g ai ha-1 of glyphosate at 28 and 56 dap; t5 - soybean brs 244 rr, with one application of 100 g ai ha-1 of imazethapyr at 28 dap; and t6 - soybean brs 154 with one application of 100 g ai ha-1 of imazethapyr at 28 dap. it was verified that the glyphosate application for weed control resulted in high levels of glyphosate and aminomethylphosphonic acid on the soil. the levels of isoflavone in the grains apparently were not affected by the glyphosate application, but the herbicide residues were higher than the current amount allowed by the legislation (10 mg.kg-1).
Estudo de recupera??o de glifosato e AMPA derivados em solo utilizando-se resinas nacionais
Souza, Tomaz Alves de;Matta, Marcia Helena de Rizzo da;Montagner, émerson;Abreu, Adley Bergson Gon?alves de;
Química Nova , 2006, DOI: 10.1590/S0100-40422006000600037
Abstract: in the present paper we studied the recoveries of glyphosate, n-(phosphonomethyl)glycine (gly) and its major metabolite, (aminomethyl)phosphonic acid (ampa) in soil using national (brazilian) ion-exchange resins, derivatization by a mixture of trifluoroacetic anhydride and trifluoroethanol and analyses by gc-ms. the quantification limits were 12 ng.g-1 for both compounds and the methodology showed a range of recuperation from 85 to 94% with coefficients of variation (cv) ranging from 4.07 to 6.91% for gly. for ampa, the mean recoveries ranged from 87 to 102% with cvs ranging from 5.81 to 6.99%. additional studies showed that, due to the instability of the derivatized compounds, they must be analysed keeping constant time between derivatization and analysis, preferably less than 24 h.
Regulation of Excitatory Synapses and Fearful Memories by Stress Hormones
Harm J. Krugers
Frontiers in Behavioral Neuroscience , 2011, DOI: 10.3389/fnbeh.2011.00062
Abstract: Memories for emotionally arousing and fearful events are generally well retained. From the evolutionary point of view this is a highly adaptive behavioral response aimed to remember relevant information. However, fearful memories can also be inappropriately and vividly (re)expressed, such as in posttraumatic stress disorder. The memory formation of emotionally arousing events is largely modulated by hormones, peptides, and neurotransmitters which are released during and after exposure to these conditions. One of the core reactions in response to a stressful situation is the rapid activation of the autonomic nervous system, which results in the release of norepinephrine in the brain. In addition, stressful events stimulate the hypothalamus–pituitary–adrenal axis which slowly increases the release of glucocorticoid hormones from the adrenal glands. Here we will review how glucocorticoids and norepinephrine regulate the formation of fearful memories in rodents and humans and how these hormones can facilitate the storage of information by regulating excitatory synapses.
PTEN对原代培养大鼠海马神经元牵张损伤后GluR2受体亚单位定位表达的调节作用
许民辉,程远,周椿,沈光建,徐伦山,易良
第三军医大学学报 , 2010,
Abstract: 目的探讨第10染色体同源丢失性磷酸酶张力蛋白基因(phosphataseandtensinhomologdeletedonchromosometen,PTEN)对大鼠原代海马神经元牵张损伤后AMPA受体GluR2亚单位定位表达的调节作用。方法选用新生SD大鼠培养原代海马神经元,建立神经元牵张损伤模型,利用RNAi慢病毒载体敲减神经元中PTEN基因的表达。采用Tunel染色评估神经元牵张各时相点的损伤情况。采用Westernblot检测牵张各时相点AMPA受体GluR2亚单位在细胞中的表达定位变化。结果慢病毒介导的RNAi能有效下调PTEN基因的表达。PTEN基因表达下调后,0、2、6h细胞凋亡比例无明显差异,但24h细胞凋亡比例由(68.7%±5.1%)下降至(39.3%±3.5%),48h细胞凋亡比例由(76.7%±5.3%)下降至(52.0%±4.3%)。神经元细胞膜中的AMPA受体GluR2亚单位含量在牵张损伤6、24、48h明显降低。下调PTEN基因的表达后,神经元细胞膜中的AMPA受体GluR2亚单位含量在牵张损伤6h无明显降低,牵张损伤24、48h后降低。细胞损伤6、24、48h时,下调PTEN基因的表达能够明显上调神经元细胞膜中的AMPA受体GluR2亚单位含量。结论海马神经元受到机械性牵张损伤后,下调PTEN的表达能够有效地阻止AMPA受体GluR2亚单位在细胞膜上定位的降低,降低凋亡细胞比例。PTEN对AMAP受体的调节作用可能为预防和治疗脑创伤提供一条新途径。
Postnatal developmental alterations in the locus coeruleus neuronal fast excitatory postsynaptic currents mediated by ionotropic glutamate receptors of rat
Masoumeh Kourosh Arami,Saeed Semnanian,Mohammad Javan,Sohrab Hajizadeh
Physiology and Pharmacology , 2011,
Abstract: Introduction: In the present work, spontaneous postsynaptic currents were assessed to investigate the postnatal development of excitatory postsynaptic currents in locus coeruleus neurons. Methods: In this study, AMPA and NMDA receptor-mediated spontaneous synaptic currents in the neurons of locus coeruleus were assessed using whole cell voltage-clamp recording during the first three weeks. Results: The frequency and amplitude of NMDA sEPSCs and the frequency of AMPA sEPSCs were increased in the second and third postnatal weeks compared with these parameters recorded in the first postnatal week. However, the ratio of the AMPA to NMDA current frequency and amplitude was constant until the 3rd postnatal week. Conclusion: These findings suggest that a vast majority of nascent glutamatergic synapses express both functional AMPA and NMDA receptors in the postnatal locus coeruleus, so that AMPA/NMDA sEPSCs remained constant during this period.
Efecto neuroprotector de los cannabinoides sobre la muerte neuronal inducida por Ampa en la médula espinal: Activación conjunta de los receptores CB1 y CB2
V. Mu?etón Gómez,F. Docagne,Joaquín Sancho,Manuel Nieto Sampedro
Iatreia , 2005,
Abstract: La sobreactivación de receptores de glutamato, como el receptor AMPA, induce la muerte neural por un proceso denominado excitotoxicidad, el cual ha sido claramente implicado en enfermedades agudas del sistema nerviso central (SNC), particularmente con da o axonal.
Peripheral nerve injury increases glutamate-evoked calcium mobilization in adult spinal cord neurons
Doolen Suzanne,Blake Camille B,Smith Bret N,Taylor Bradley K
Molecular Pain , 2012, DOI: 10.1186/1744-8069-8-56
Abstract: Background Central sensitization in the spinal cord requires glutamate receptor activation and intracellular Ca2+ mobilization. We used Fura-2 AM bulk loading of mouse slices together with wide-field Ca2+ imaging to measure glutamate-evoked increases in extracellular Ca2+ to test the hypotheses that: 1. Exogenous application of glutamate causes Ca2+ mobilization in a preponderance of dorsal horn neurons within spinal cord slices taken from adult mice; 2. Glutamate-evoked Ca2+ mobilization is associated with spontaneous and/or evoked action potentials; 3. Glutamate acts at glutamate receptor subtypes to evoked Ca2+ transients; and 4. The magnitude of glutamate-evoked Ca2+ responses increases in the setting of peripheral neuropathic pain. Results Bath-applied glutamate robustly increased [Ca2+]i in 14.4 ± 2.6 cells per dorsal horn within a 440 x 330 um field-of-view, with an average time-to-peak of 27 s and decay of 112 s. Repeated application produced sequential responses of similar magnitude, indicating the absence of sensitization, desensitization or tachyphylaxis. Ca2+ transients were glutamate concentration-dependent with a Kd = 0.64 mM. Ca2+ responses predominantly occurred on neurons since: 1) Over 95% of glutamate-responsive cells did not label with the astrocyte marker, SR-101; 2) 62% of fura-2 AM loaded cells exhibited spontaneous action potentials; 3) 75% of cells that responded to locally-applied glutamate with a rise in [Ca2+]i also showed a significant increase in AP frequency upon a subsequent glutamate exposure; 4) In experiments using simultaneous on-cell recordings and Ca2+ imaging, glutamate elicited a Ca2+ response and an increase in AP frequency. AMPA/kainate (CNQX)- and AMPA (GYKI 52466)-selective receptor antagonists significantly attenuated glutamate-evoked increases in [Ca2+]i, while NMDA (AP-5), kainate (UBP-301) and class I mGluRs (AIDA) did not. Compared to sham controls, peripheral nerve injury significantly decreased mechanical paw withdrawal threshold and increased glutamate-evoked Ca2+ signals. Conclusions Bulk-loading fura-2 AM into spinal cord slices is a successful means for determining glutamate-evoked Ca2+ mobilization in na ve adult dorsal horn neurons. AMPA receptors mediate the majority of these responses. Peripheral neuropathic injury potentiates Ca2+ signaling in dorsal horn.
Are AMPA Receptor Positive Allosteric Modulators Potential Pharmacotherapeutics for Addiction?
Lucas R. Watterson,M. Foster Olive
Pharmaceuticals , 2014, DOI: 10.3390/ph7010029
Abstract: Positive allosteric modulators (PAMs) of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors are a diverse class of compounds that increase fast excitatory transmission in the brain. AMPA PAMs have been shown to facilitate long-term potentiation, strengthen communication between various cortical and subcortical regions, and some of these compounds increase the production and release of brain-derived neurotrophic factor (BDNF) in an activity-dependent manner. Through these mechanisms, AMPA PAMs have shown promise as broad spectrum pharmacotherapeutics in preclinical and clinical studies for various neurodegenerative and psychiatric disorders. In recent years, a small collection of preclinical animal studies has also shown that AMPA PAMs may have potential as pharmacotherapeutic adjuncts to extinction-based or cue-exposure therapies for the treatment of drug addiction. The present paper will review this preclinical literature, discuss novel data collected in our laboratory, and recommend future research directions for the possible development of AMPA PAMs as anti-addiction medications.
Phenobarbital but Not Diazepam Reduces AMPA/kainate Receptor Mediated Currents and Exerts Opposite Actions on Initial Seizures in the Neonatal Rat Hippocampus
Yehezkel Ben-Ari
Frontiers in Cellular Neuroscience , 2011, DOI: 10.3389/fncel.2011.00016
Abstract: Diazepam (DZP) and phenobarbital (PB) are extensively used as first and second line drugs to treat acute seizures in neonates and their actions are thought to be mediated by increasing the actions of GABAergic signals. Yet, their efficacy is variable with occasional failure or even aggravation of recurrent seizures questioning whether other mechanisms are not involved in their actions. We have now compared the effects of DZP and PB on ictal-like events (ILEs) in an in vitro model of mirror focus (MF). Using the three-compartment chamber with the two immature hippocampi and their commissural fibers placed in three different compartments, kainate was applied to one hippocampus and PB or DZP to the contralateral one, either after one ILE, or after many recurrent ILEs that produce an epileptogenic MF. We report that in contrast to PB, DZP aggravated propagating ILEs from the start, and did not prevent the formation of MF. PB reduced and DZP increased the network driven giant depolarizing potentials suggesting that PB may exert additional actions that are not mediated by GABA signaling. In keeping with this, PB but not DZP reduced field potentials recorded in the presence of GABA and NMDA receptor antagonists. These effects are mediated by a direct action on AMPA/kainate receptors since PB: (i) reduced AMPA/kainate receptor mediated currents induced by focal applications of glutamate; (ii) reduced the amplitude and the frequency of AMPA but not NMDA receptor mediated miniature excitatory postsynaptic currents (EPSCs); (iii) augmented the number of AMPA receptor mediated EPSCs failures evoked by minimal stimulation. These effects persisted in MF. Therefore, PB exerts its anticonvulsive actions partly by reducing AMPA/kainate receptors mediated EPSCs in addition to the pro-GABA effects. We suggest that PB may have advantage over DZP in the treatment of initial neonatal seizures since the additional reduction of glutamate receptors mediated signals may reduce the severity of neonatal seizures.
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