Browsing by Author "Vergara, Ana"

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    Dynamic Expression of Follicle-Stimulating Hormone and Estrogen mRNA Receptors Associated with microRNAs 34a and -let-7c in Canine Follicles during the Estrous Cycle
    (2024) De los Reyes, Monica; Dettleff, Phillip; Palomino, Jaime; Peralta, Oscar A.; Vergara, Ana
    The genes encoding for estrogen receptor (ESR2) and follicle-stimulating hormone receptor (FSHR) play crucial roles in ovarian follicular development. This study aimed to determine the expression levels of miRNAs predicted against FSHR and ESR2 mRNAs in follicular cells related to their target genes during the estrous cycle in canines. Antral follicles were dissected from 72 ovaries following ovariohysterectomies. MiRNAs regulating FSHR and ESR2 genes were selected from miRNA databases, and mature miRNA and mRNA expression profiling was performed using real-time polymerase chain reaction (PCR). The best miRNA for each target gene was selected considering the quantitative PCR (qPCR) performance and target prediction probability, selecting only miRNAs with a binding p-value of 1.0, and choosing cfa-miR-34a and cfa-let-7c for FSHR and ESR2, respectively. The expression levels comparing the different phases of the estrous cycle were evaluated using ANOVA. Pearson correlations between the expression pattern of each miRNA and their target genes were performed. Each miRNA and its target genes were expressed in the granulosa cells in all estrous phases. FSHR remained low in anestrus and proestrus, increased (p < 0.05) to the highest level in estrus, and decreased (p < 0.05) in diestrus. ESR2 showed the same trend as FSHR, with the highest (p < 0.05) expression in estrus and the lowest (p < 0.05) in anestrus and proestrus. A tendency for an inverse relationship was observed between the expression of miR-34a and FSHR only in the anestrus phase, while an inverse correlation (r = -0.8) was found between miRNA-7c and ESR2 (p < 0.01). The expression profile of miR-34a and miR-let-7c and their predicted target genes of dog ovarian follicles throughout the estrous cycle observed in this study suggest a role in the transcriptional regulation of FSHR and ESR2, which is the first evidence of the involvement of these miRNAs in the canine follicular function.
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    Rhenium-Based Electrocatalysts for Water Splitting
    (2023) Ramírez, Andrés M. R.; Heidari, Sima; Vergara, Ana; Villicaña Aguilera, Miguel; Preuss, Paulo; Camarada Uribe, María Belén Montserrat; Fischer, Anna
    Due to the contaminationand global warming problems, it is necessaryto search for alternative environmentally friendly energy sources.In this area, hydrogen is a promising alternative. Hydrogen is evenmore promising, when it is obtained through water electrolysis operatedwith renewable energy sources. Among the possible devices to performelectrolysis, proton exchange membrane (PEM) electrolyzers appearas the most promising commercial systems for hydrogen production inthe coming years. However, their massification is affected by thenoble metals used as electrocatalysts in their electrodes, with highcommercial value: Pt at the cathode where the hydrogen evolution reactionoccurs (HER) and Ru/Ir at the anode where the oxygen evolution reaction(OER) happens. Therefore, to take full advantage of the PEM technologyfor green H-2 production and build up a mature PEM market,it is imperative to search for more abundant, cheaper, and stablecatalysts, reaching the highest possible activities at the lowestoverpotential with the longest stability under the harsh acidic conditionsof a PEM. In the search for new electrocatalysts and considering thepredictions of a Trasatti volcano plot, rhenium appears to be a promisingcandidate for HER in acidic media. At the same time, recent studiesprovide evidence of its potential as an OER catalyst. However, someof these reports have focused on chemical and photochemical watersplitting and have not always considered acidic media. This reviewsummarizes rhenium-based electrocatalysts for water splitting underacidic conditions: i.e., potential candidates as cathode materials.In the various sections, we review the mechanism concepts of electrocatalysis,evaluation methods, and the different rhenium-based materials appliedfor the HER in acidic media. As rhenium is less common for the OER,we included a section about its use in chemical and photochemicalwater oxidation and as an electrocatalyst under basic conditions.Finally, concluding remarks and perspectives are given about rheniumfor water splitting.
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