Publications by authors named "Javier Plasencia"

Fusarium spp. comprise various species of filamentous fungi that cause severe diseases in plant crops of both agricultural and forestry interest. These plant pathogens produce a wide range of molecules with diverse chemical structures and biological activities.

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Multiple studies have shown that testing contributes to learning at all educational levels. In this observational classroom study, we report the use of a learning tool developed for a Genetics and Molecular Biology course at the college level. An interactive set of practice exams that included 136 multiple choice questions (MCQ) or matching queries was developed in the open-source Moodle platform.

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An undergraduate online course on Applied Biochemistry and Molecular Biology was developed through different formats of case study that included lecture, class discussion, small-groups discussion, and individual work. Cases covering health, biotechnology, agriculture, and other issues were developed or adapted from the literature to reach the desired learning goals. Multiple web resources were employed for information integration that were presented and discussed in the synchronous sessions and assignments.

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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 , fumonisins accumulate to high levels in -infected maize kernels, fumonisin B1 (FB1) being the most abundant in naturally infected maize.

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is the fungal symbiont associated with the ambrosia beetle , a plague complex that attacks avocado, among other hosts, causing a disease named dieback (FD). However, the contribution of to the establishment of this disease remains unknown. To advance the understanding of pathogenicity, we profiled its exo-metabolome through metabolomics tools based on accurate mass spectrometry.

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Thymidine kinase 1 (TK1) phosphorylates thymidine nucleosides to generate thymidine monophosphate. This reaction belongs to the pyrimidine salvage route that is phylogenetically conserved. In the model plant , TK activity contributes to maintain nuclear and organellar genome integrity by providing deoxythymidine-triphosphate (dTTP) for DNA synthesis.

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Fumonisin B1 is a mycotoxin produced by that modifies the membrane properties from animal cells and inhibits complex sphingolipids synthesis through the inhibition of ceramide synthase. The aim of this work was to determine the effect of Fumonisin B1 on the plant plasma membrane when the mycotoxin was added to germinating maize embryos. Fumonisin B1 addition to the embryos diminished plasma membrane fluidity, increased electrolyte leakage, caused a 7-fold increase of sphinganine and a small decrease in glucosylceramide in the plasma membrane, without affecting phytosphingosine levels or fatty acid composition.

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species are fungi widely employed as plant-growth-promoting agents and for biological control. Several commercial and laboratory-made solid formulations for mass production of have been reported. In this study, we evaluated a solid kaolin-based formulation to promote the absortion/retention of in the substrate for growing tomato plants.

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Nucleotide biosynthesis proceeds through a de novo pathway and a salvage route. In the salvage route, free bases and/or nucleosides are recycled to generate the corresponding nucleotides. Thymidine kinase (TK) is the first enzyme in the salvage pathway to recycle thymidine nucleosides as it phosphorylates thymidine to yield thymidine monophosphate.

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Objective: To obtain micro propagated Uncaria tomentosa plantlets with enhanced secondary metabolites production, long-term responses to salicylic acid (SA) pre-treatments at 1 and 100 µM were evaluated after propagation of the plantlets in a SA-free medium.

Results: SA pre-treatments of single node cuttings OF U. tomentosa produced long-term responses in microplants grown for 75 days in a SA-free medium.

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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.

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Thymidine kinase catalyzes the first step in the nucleotide salvage pathway by transferring a phosphate group to a thymidine molecule. In mammals thymidine kinase supplies deoxyribonucleotides for DNA replication and DNA repair, and the expression of the gene is tightly regulated during the cell cycle. Although this gene is phylogenetically conserved in many taxa, its physiological function in plants remains unknown.

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Sphingolipids play an important role in signal transduction pathways that regulate physiological functions and stress responses in eukaryotes. In plants, recent evidence suggests that their metabolic precursors, the long-chain bases (LCBs) act as bioactive molecules in the immune response. Interestingly, the virulence of two unrelated necrotrophic fungi, Fusarium verticillioides and Alternaria alternata, which are pathogens of maize and tomato plants, respectively, depends on the production of sphinganine-analog mycotoxins (SAMs).

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Fusarium verticillioides is an important pathogen in maize that causes various diseases affecting all stages of plant development worldwide. The fungal pathogen could be seed borne or survive in soil and penetrate the germinating seed. Most F.

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In recent years salicylic acid (SA) has been the focus of intensive research due to its function as an endogenous signal mediating local and systemic plant defence responses against pathogens. It has also been found that SA plays a role during the plant response to abiotic stresses such as drought, chilling, heavy metal toxicity, heat, and osmotic stress. In this sense, SA appears to be, just like in mammals, an 'effective therapeutic agent' for plants.

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Fumonisin B(1) (FB(1)) is an amphipathic toxin produced by the pathogenic fungus Fusarium verticillioides which causes stem, root and ear rot in maize (Zea mays L.). In this work, we studied the action of FB(1) on the plasma membrane H(+)-ATPase (EC 3.

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Alkaline-cooked corn, called nixtamal, is the basis for many traditional corn products such as tortillas, chips, and taco shells that are used widely in Mexico and Central America and in the preparation of snack foods that are consumed globally. To assess the effects of alkaline and thermal treatments on the detectability of DNA and protein for the presence of genetically modified sequences, various nixtamalized products were prepared from blends of conventional white corn containing 0.1, 1.

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DNA polymerase and DNA primase activities in the maize alpha-type DNA polymerase 2 were dissociated and DNA polymerase-free DNA primase was studied. DNA primase synthesized primers that were 8-34 nucleotides long, with more intense bands at 15-17 nucleotides in length. DNA polymerase 1 (a putative delta-type enzyme) or DNA polymerase 2 were assayed after template-priming with purified DNA primase and showed a differential use of templates: whereas DNA polymerase 2 used a polydT template more efficiently than a natural template, DNA polymerase 1 used both of them poorly.

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Vascular colonization by Verticillium dahliae of 14 potato (Solanum tuberosum) cultivars was evaluated in field trials by a culture plate method and an indirect competitive enzyme-linked immunosorbent assay (IC-ELISA). Whereas the culture plate technique quantifies fungal propa-gules, the monoclonal antibody-based immunoassay detects the soluble antigen, providing an indicator of fungal biomass. Differences in vascular colonization were evident with both methods; thus, cultivars could be ranked as susceptible, intermediate, or resistant.

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