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Fusarium verticillioides is a fungal pathogen of maize that causes seedling blight, stem rot, and Fusarium ear rot. Fungal infestation of maize kernels and ears affects grain quality from the ensuing mycotoxin buildup. Among the mycotoxins produced by F. verticillioides, fumonisins accumulate to high levels in Fusarium-infected maize kernels, fumonisin B1 (FB1) being the most abundant in naturally infected maize. Achieving resistance to Fusarium ear rot has been challenging, as various environmental factors facilitate fungal infection. Among the maize grain components that contribute to resistance to F. verticillioides infection, the pericarp is the first barrier faced by the fungus and thus plays a key role. Phenolic acids are major constituents of maize pericarp, of which ferulic acid (FA) is the predominant molecular species. In this work, we explored the relationship between FA levels, fungal infection, and FB1 production in 51 maize genotypes and whether the antioxidant activity of FA might play a role. We confirmed that FA is a major component of the seed pericarp, whose levels as bound FA varied between 4.5 and 26.3 mg/g across maize genotypes. We selected two pools of five maize varieties, with contrasting FA contents: low FA (LFA; 6.14 ± 0.40 mg/g) and high FA (HFA; 15.49 ± 1.31 mg/g). In vitro, HFA extracts inhibited fungal growth with effects comparable to FA concentrations in the 0.25-0.50 mM range. We also established a kernel assay to study F. verticillioides colonization and FB1 production in the LFA and HFA genotypes. Fungal colonization was significantly lower in HFA genotypes relative to LFA genotypes, based on ergosterol levels. Moreover, FB1 production was also inhibited in the HFA genotypes. Importantly, the antioxidant activity of maize pericarp extracts was associated with FA contents, with HFA extracts exhibiting a greater antioxidant activity than LFA extracts. Overall, our results highlight the role of FA and its antioxidant activity on resistance to Fusarium ear rot and provide the basis of a phenotypic trait that can be deployed for breeding selection.

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The field of plant sphingolipid biology has evolved in recent years. Sphingolipids are abundant in cell membranes, and genetic analyses revealed essential roles for these lipids in plant growth, development, and responses to abiotic and biotic stress. Salicylic acid (SA) is a key signaling molecule that is required for induction of defense-related genes and rapid and localized cell death at the site of pathogen infection (hypersensitive response) during incompatible host-pathogen interactions. Conceivably, while levels of SA rapidly increase upon pathogen infection for defense activation, they must be tightly regulated during plant growth and development in the absence of pathogens. Genetic and biochemical evidence suggest that the sphingolipid intermediates, long-chain sphingoid bases, and ceramides, play a role in regulating SA accumulation in plant cells. However, how signals generated from the perturbation of these key sphingolipid intermediates are transduced into the activation of the SA pathway has long remained to be an interesting open question. At least four types of molecules - MAP kinase 6, reactive oxygen species, free calcium, and nitric oxide - could constitute a mechanistic link between sphingolipid metabolism and SA accumulation and signaling.

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Objetivo: Proponer un proceso de desregulación de alimentos derivados de cultivos genéticamente mejorados desarrollados en Costa Rica, plantea un trámite a la Consulta de desregulación de un nuevo alimento desarrollado por ingeniería genética, labor que le competerá al Ministerio de Salud principalmente. Material y métodos: La propuesta incluye procedimientos de iniciar la consulta, conformación del equipo de evaluadores, información que se solicita en el dossier sobre alimentos derivados de cultivos genéticamente mejorados, y comunicación de la decisión de la Consulta. Se construyó con base a marcos regulatorios de bioseguridad, utilizados en países desarrollados, que orientan a los desarrolladores en los lineamientos a seguir para la desregulación de los nuevos alimentos. Resultados: Lo que establecen los marcos de regulación responde a lo planteado en el concepto de equivalencia sustancial, aceptada internacionalmente como el compendio de información que refleja la inocuidad de un alimento seguro para el consumo. El ensayo revisa los procesos de regulación en bioseguridad de Costa Rica y la experiencia en la regulación para el cultivo y movilización de materiales modificados genéticamente. Discusión: Se evidencia que Costa Rica se carece de un procedimiento para atender Consulta de desregulación de alimentos sometidos al proceso de equivalencia sustancial.

Objective: To develop a feasibility analysis of the implementation of a consultation process as it would apply to foods derived from genetically modified crops in Costa Rica; this includes a general proposal for procedures for a consultation request within the country, in order to deregulate foods derived from genetically modified crops. The Ministry of Health would be responsible for the Consultation. Methods: The proposal includes procedures for Consultation reception, group of experts for evaluation, information required in the dossier of genetically-modified crops and Consultation resolution communication. The proposal was constructed based on biosafety regulatory frameworks, used by industrialized countries, which are meant to guide developers on guidelines for the safety assessment of novel foods.Results: These guidelines follow the substantial equivalence concept, which defines what information should be accepted internationally to demonstrate that the new food is safe for human and animal consumption. In this essay a review of the biosecurity regulatory procedures in Costa Rica is presented; this review indicates that there is expertise on the regulation of planting and mobilization of GM materials.Discussion: However there is a lack of procedures addressed to doing a Consultation for deregulating a GM food that has completed the substantial equivalence process.

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Two protocols were tested to assess anticonvulsant efficacy and drug concentrations after intracerebroventricular (i.c.v.) continuous valproic acid (VPA) infusion, as compared with acute injections in the kindling epilepsy model. Protocol 1: amygdala-kindled rats were injected via intraperitoneal (i.p.) and i.c.v. routes with varying doses of VPA and tested for seizure intensity, afterdischarge and seizure duration, ataxia and sedation. Concentrations of VPA were determined by immunofluorescence in the brain, plasma, cerebrospinal fluid (CSF) and liver in matching rats. Protocol 2: amygdala-kindled rats were implanted with osmotic minipumps containing a VPA solution in saline and connected to intraventricular catheters for 7 days. Seizure threshold, latency and duration, afterdischarge duration, ataxia and sedation were recorded daily before, during, and until 5 days after VPA infusion. In matching animals, CSF, brain, plasma and liver VPA concentration was determined. Acute i.c.v. VPA injection suppressed seizures with a remarkable ataxia and sedation. However, continuous i.c.v. infusion controlled generalised and even focal seizures without producing important side effects, high plasma levels or hepatic drug concentrations. In conclusion, continuous i.c.v. VPA infusion may protect against kindled seizures by minimising ataxia and sedation, and achieving suitable intracerebral, yet low plasma or hepatic drug concentrations, thus avoiding potential systemic toxicity.

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OBJECTIVE: To explore the effect of continuous intra-amygdalar infusion of GABA in the amygdala kindling model of epilepsy in rat. METHODS: An electrode and cannula complex was implanted in adult male Wistar rats, the electrode being targeted to the left basolateral amygdala. The animals were subjected to a standard kindling procedure. Osmotic minipumps filled with either GABA or mannitol were connected to cannulas and allowed to infuse during 7 days. Kindling experiments measuring after-discharge and seizure thresholds, seizure severity and duration, and behavioral toxicity were performed before, during and after the drug infusion period. RESULTS: Both after-discharge and seizure thresholds were significantly increased both during and after GABA infusion with respect to pre-infusion controls, while the group receiving mannitol showed no significant differences. Seizure duration was not affected by GABA infusion. Seizures were either completely blocked or fully developed. CONCLUSIONS: Direct continuous GABA infusion within the epileptogenic focus raises the seizure thresholds without affecting the generalized components in the amygdala kindling model of epilepsy.

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