Miguel Walter Fornés

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We previously demonstrated that mouse sperm capacitation is accompanied by a time-dependent increase in protein tyrosine phosphorylation that is dependent on the presence of BSA, Ca2+, and NaHCO(3), all three of which are also required for this maturational event. We also demonstrated that activation of protein kinase A (PK-A) is upstream of this(More)
Testicular sperm that have undergone spermatogeneis and spermiogenesis appear mature from a morphological standpoint but have acquired neither progressive motility nor the ability to fertilize a metaphase Il-arrested egg. In many species, progressive motility and fertilization competence are acquired during epididyma! transit, but complete fertilization(More)
Lipid rafts, membrane sub-domains enriched in sterols and sphingolipids, are controversial because demonstrations of rafts have often utilized fixed cells. We showed in living sperm that the ganglioside G(M1) localized to a micron-scale membrane sub-domain in the plasma membrane overlying the acrosome. We investigated four models proposed for membrane(More)
The molecular basis of mammalian sperm capacitation, defined as those biochemical and functional changes that render the sperm competent to fertilize the egg, is poorly understood. This extratesticular maturational process is accompanied by the activation of a unique signal transduction pathway involving the cAMP-dependent up-regulation of protein tyrosine(More)
Aerobic incubation of rat spermatozoa in a balanced salt solution containing 10 microM of gossypol produced a loss of sperm motility. This effect was not reverted by the presence of 25 mM Theophylline, a well-known stimulant of motility, but was significantly diminished by the addition of 10 mM Mannitol. As mannitol is a superoxide scavenger and we found a(More)
Extensive work was done regarding the ability of Swim up and Percoll gradient to select functional sperm for in vitro embryo production (IVP) systems. The aim of this work was to compare Swim up and Percoll as methods of sperm selection by ultrastructural, biochemical and functional studies. Frozen-thawed semen from two bulls (Experiments 1 and 2,(More)
Rat spermatozoa main lipid classes and their fatty acids were studied to assess their possible changes in capacitation and the acrosomal reaction (AR), induced in vitro. Capacitation-associated protein tyrosine phosphorylation, and the efflux of 30% of the total cholesterol from gametes to the medium, took place concomitantly with the release of a similar(More)
Sphingolipids from rodent testis and spermatozoa are known to contain non-hydroxylated (N-) and 2-hydroxylated (2-OH) very-long-chain polyunsaturated fatty acids (VLCPUFA). In this study, the contribution of species with each type of fatty acids to the total ceramides (Cer) and sphingomyelins (SM) was investigated in rat and mouse testis and in rat(More)
The epithelium of caput and cauda epididymidis of the rat was studied with transmission electron microscopy (TEM) and freeze-fracture techniques. In thin sections of both zones, the tissue consisted mainly of tall columnar cells (principal cells) with long sterocilia. Clusters of small membrane-bound vesicles were located in the lumen between or immediately(More)
Whole seminal plasma (SP) enhances the function and fertility of frozen/thawed ram sperm. The objective of the current study was to investigate whether SP proteins capable of binding to molecules from the sperm plasma membrane were conserved among ram breeds, and whether these proteins were sufficient to overcome cryopreservation-induced reductions in sperm(More)