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García Vázquez, Francisco Alberto

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García Vázquez, Francisco Alberto
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Universidad de Murcia. Departamento de Fisiología
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    Epididymal and ejaculated sperm functionality is regulated differently by periovulatory oviductal fluid in pigs
    (Wiley, 2020-09-13) Soriano-Úbeda, Cristina; Avilés-López, Karen; García Vázquez, Francisco Alberto; Romero Aguirregomezcorta, Jon; Matas Parra, Carmen; Anatomía y Anatomía Patológica Comparada; Facultad de Veterinaria
    Background: The current results of in vitro reproduction techniques in pigs, such as in vitro fertilization (IVF) and embryo development, show high performance with both epididymal and ejaculated spermatozoa. However, the results using ejaculated spermatozoa are even better. Ejaculated spermatozoa are exposed to the secretions of the accessory seminal glands: the seminal plasma (SP). It has been reported that exposure of spermatozoa to reproductive fluids, such as SP or periovulatory oviductal fluid (pOF), modulates sperm functionality both in vivo and in vitro. But whether or not this modulating effect of pOF depends on the origin of the spermatozoa being epididymal or ejaculated, is still unknown. Objectives: To determine and compare the effect of pOF on epididymal and ejaculated sperm functionality. Material and methods: The effects of incubating spermatozoa from the epididymis and ejaculate with pOF in capacitating conditions were investigated by analyzing sperm motility, phosphorylation of protein kinase A substrates and proteins in tyros ine (pPKAs and pTyr, respectively), the interaction of the spermatozoa with the oocyte in IVF and intracytoplasmic sperm injection (ICSI), and, finally, the spermatozoa chromatin condensation status.Results: the pOF modified events related to capacitation in epididymal spermatozoa by decreasing motility, pPKAs and pTyr. In the interaction with the oocyte after sperm capacitation, pOF regulated the epididymal and ejaculated spermatozoa differently. While pOF decreased the number of spermatozoa bound to the zona pellucida (Spz/ZP) and increased oocyte activation after ICSI with epididymal spermatozoa, with the ejaculated spermatozoa, it decreased the mean number penetrating each oocyte (Spz/O). Additionally, pOF significantly increased the nuclear decondensation of the epididymal spermatozoa after the fertilization of the oocyte.Conclusion: The modulation of sperm functionality by pOF is conditioned by the origin of the spermatozoa.
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    Manipulation of bicarbonate concentration in sperm capacitation media improves in vitro fertilisation output in porcine species
    (BioMed Central, 2019-03-11) Soriano-Úbeda, Cristina; Romero Aguirregomezcorta, Jon; Matas Parra, Carmen; Visconti, Pablo E.; García Vázquez, Francisco Alberto; Anatomía y Anatomía Patológica Comparada; Facultad de Veterinaria
    Background. The in vivo concentration of bicarbonate (HCO3−), one of the essential sperm capacitating effectors, varies greatly in the different environments sperm go through from cauda epididymis to the fertilisation site. On the contrary, porcine in vitro sperm capacitation and fertilisation media usually contains a standard concentration of 25 mmol/L, and one of the main problems presented is the unacceptable high incidence of polyspermy. This work hypothesised that by modifying the HCO3− concentration of the medium, the output of in vitro sperm capacitation and fertilisation could be increased. Results: Once exposed to the capacitation medium, the intracellular pH (pHi) of spermatozoa increased immediately even at low concentrations of HCO3−, but only extracellular concentrations of and above 15 mmol/L increased the substrates protein kinase A phosphorylation (pPKAs). Although with a significant delay, 15 mmol/L of HCO3− stimulated sperm linear motility and increased other late events in capacitation such as tyrosine phosphorylation (Tyr-P) to levels similar to those obtained with 25 mmol/L. This information allowed the establishment of a new in vitro fertilisation (IVF) system based on the optimization of HCO3− concentration to 15 mmol/L, which led to a 25.3% increment of the viable zygotes (8.6% in the standard system vs. 33.9%). Conclusions: Optimising HCO3− concentrations allows for establishing an IVF method that significantly reduced porcine polyspermy and increased the production of viable zygotes. A concentration of 15 mmol/L of HCO3− in the medium is sufficient to trigger the in vitro sperm capacitation and increase the fertilisation efficiency in porcine.
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