Biomedical subjects

Carmen Matás

Publications and source records attributed to Carmen Matás.

6 recordsLinked to original sources

PubMed2006

Analysis of different factors influencing the intracytoplasmic sperm injection (ICSI) yield in pigs.

Intracytoplasmic sperm injection (ICSI) in pigs is a technique with potential application in diverse fields of animal production and biomedicine. Even though there are some cases of live offspring resulting from this technique, its yield is still quite low compared to other species. The aim of this study was to evaluate different factors affecting the ICSI performance. This was done by studying (1) the sequence of culture media for the oocytes after injection; (2) modifications in the in vitro maturation system (IVM) through meiotic inhibitors such as roscovitine, and changes in the IVM time; (3) oocyte activation through injection of inositol triphosphate (InsP(3)) together with the sperm. In vitro matured oocytes were employed. All the ICSI experiments were performed with fresh ejaculated semen. Results showed that porcine ICSI zygotes give an improved proportion of two-cell embryos using the sequence IVF medium-embryo culture medium (NCSU-23) rather than transferring directly to NCSU-23. Pronuclear formation ability was not affected by prematuration, but a faster embryo development was observed in roscovitine treated oocytes. In relation to IVM times, oocytes matured for 36 h can achieve better fertilization percentages than oocytes matured for 44 h. These results were independent of the roscovitine treatment. Finally, no influence on embryo development was observed until the blastocyst stage with the use of the InsP(3) as an exogenous activating factor.

Animals↗

PubMed2005

Influence of sperm pretreatment on the efficiency of intracytoplasmic sperm injection in pigs.

The purpose of this study was to determine the influence of sperm pretreatment on the efficiency of intracytoplasmic sperm injection (ICSI) in pigs. This was done by examining the effect of 1) the conservation method (fresh vs frozen); 2) the sperm treatment preinjection (resuspension in Dulbecco phosphate-buffered saline (DPBS) vs selection by a Percoll gradient); and 3) the acrosomal and live or dead status of the spermatozoa (by incubation with or without calcium ionophore, 1 muM and 5 muM). In vitro matured porcine oocytes were injected with treated spermatozoa according to each experiment. All the experiments were done with non-artificially activated oocytes. The percentages of activation and cleavage were higher (68% vs 43% and 63% vs 43%, respectively, P < .05) in oocytes injected with fresh vs frozen spermatozoa. The DPBS treatment allowed higher cleavage proportions than the Percoll treatment (P < .05). Moreover, a boar effect was observed in the percentage of developing blastocysts. None of the studied parameters was affected by the acrosomal or the live or dead status of the spermatozoa injected. In conclusion, the use of fresh semen is recommended for porcine ICSI, as well as careful selection of the boar; Percoll treatment is only recommended for poor-quality samples or for removing toxic agents, and no exogenous form of activation or induction of the acrosome reaction is necessary for porcine oocytes to develop a male pronucleus and cleave up to the 2-cell stage after ICSI, although experimental conditions to reach the blastocyst stage need to be investigated further.

Animals↗

PubMed2005

Birth of piglets after transferring of in vitro-produced embryos pre-matured with R-roscovitine.

The objectives of this study were to evaluate: (1) the nuclear maturation, (2) the intracellular glutathione (GSH) content, (3) the normality of fertilization and (4) full development after transplantation of embryos derived from porcine oocytes pre-cultured with 50 micromol/l roscovitine (an inhibitor of p34cdc2/cyclin B kinase) for 22 h. After treatment with roscovitine, the nuclear configuration of oocytes (Hoechst staining) was comparable with those examined just after collection: the majority of oocytes were arrested at the germinal vesicle (GV) 1 stage (63.2%). Roscovitine-treated oocytes progressed through meiosis to the metaphase II stage in a conventional step-wise in vitro maturation (IVM) program for 44 h in a proportion similar to control ones (>85.0%). When roscovitine-treated oocytes and non-treated oocytes were matured for 44 h and then co-cultured with fresh spermatozoa for 18 h, no differences were observed in oocyte penetrability, proportion of monospermic penetration and male pronuclear formation (>87%). Roscovitine increased the GSH synthesis in oocytes at 22 h, whereas, after 44 h, roscovitine-treated oocytes had similar amounts of GSH to non-treated oocytes. Finally, surgical transfer of zygotes at 22-24 h post-insemination, derived from roscovitine-treated oocytes, resulted in one pregnancy with 12 piglets born; control non-treated zygotes resulted in one pregnancy and 10 piglets born. The full-term developmental ability of mammalian oocytes pre-cultured with roscovitine prior to IVM is thereby demonstrated. This validation is important before the introduction of roscovitine into routine procedures.

Animals↗

PubMed2004

Decrease in glutathione content in boar sperm after cryopreservation. Effect of the addition of reduced glutathione to the freezing and thawing extenders.

Although glutathione content in boar spermatozoa has been previously reported, the effect of reduced glutathione (GSH) on semen parameters and the fertilizing ability of boar spermatozoa after cryopreservation has never been evaluated. In this study, GSH content was determined in ejaculated boar spermatozoa before and after cryopreservation. Semen samples were centrifuged and GSH content in the resulting pellet monitored spectrophotometrically. The fertilizing ability of frozen-thawed boar sperm was also tested in vitro by incubating sperm with in vitro matured oocytes obtained from gilts. GSH content in fresh semen was 3.84 +/- 0.21 nM GSH/10(8) sperm. Following semen cryopreservation, there was a 32% decrease in GSH content (P < 0.0001). There were significant differences in sperm GSH content between different boars and after various preservation protocols (P = 0.0102 ). The effect of addition of GSH to the freezing and thawing extenders was also evaluated. Addition of 5 mM GSH to the freezing extender did not have a significant effect on standard semen parameters or sperm fertilizing ability after thawing. In contrast, when GSH was added to the thawing extender, a dose-dependent tendency to increase in sperm fertilizing ability was observed, although no differences were observed in standard semen parameters. In summary, (i) there was a loss in GSH content after cryopreservation of boar semen; (ii) addition of GSH to the freezing extender did not result in any improvement in either standard semen parameters or sperm fertilizing ability; and (iii) addition of GSH to the thawing extender resulted in a significant increase in sperm fertilizing ability. Nevertheless, future studies must conclude if this is the case for all boars. Furthermore, since addition of GSH to the thawing extender did not result in an improvement in standard semen parameters, this suggests that during the thawing process, GSH prevents damage of a sperm property that is critical in the fertilization process but that is not measured in the routine semen analysis.

Animals↗

PubMedDate not supplied

Cooling and freezing of boar spermatozoa: supplementation of the freezing media with reduced glutathione preserves sperm function.

In this study, we evaluated the effects of glutathione (L-gamma-glutamyl-L-cysteinylglycine; GSH) supplementation of the freezing extender on semen parameters during the cooling (2 hours at 5 degrees C) and freezing phases of the cryopreservation process to compensate for the decrease in GSH content observed during sperm freezing. To fully address these questions, we incorporated a new set of functional sperm tests. These included tests of mitochondrial function, inducibility of the acrosome reaction, in vitro penetration (IVP) of oocytes, changes in sulfhydryl group content in membrane proteins, and capacitation status. The main findings emerging from this study were that the addition of GSH to the freezing media resulted in 1) an improvement in percent motility (%MOT) and motion parameters of thawed spermatozoa, as measured by both microscopic analysis and computer-assisted semen analysis (CASA); 2) a higher number of total viable spermatozoa; 3) a higher number of noncapacitated viable spermatozoa; and 4) a decrease in the number of spermatozoa with changes in the sulfhydryl groups in membrane proteins. This protective effect on sperm function was more pronounced with 1 mM of GSH than with 5 mM of GSH.

Acrosome Reaction↗

PubMedDate not supplied

Supplementation of the thawing media with reduced glutathione improves function and the in vitro fertilizing ability of boar spermatozoa after cryopreservation.

In this study, we evaluated the effects of glutathione (L-g-glutamyl-L-cysteinylglycine; GSH) supplementation of the thawing extender on semen parameters to compensate for the decrease in GSH content observed during sperm freezing. To fully address these questions, we used a set of functional sperm tests. These included tests of motility and motion parameters, changes in sulfhydryl group content in membrane proteins, capacitation status, measures of intra-cellular reactive oxygen species generation, sperm chromatin condensation, and in vitro penetration of immature oocytes. The main findings emerging from this study were that addition of GSH to the thawing media resulted in a lower number of capacitated viable spermatozoa, a decrease in the number of spermatozoa with changes in the sulfhydryl groups in membrane proteins, a reduction of the reactive oxygen species generation, a lower chromatin condensation, and a higher penetration ability of oocytes in vitro and a higher proportion of decondensated sperm heads. GSH appears to play an important role in sperm antioxidant defense strategy. Addition of GSH to the thawing extender could be of significant benefit in improving the function and fertilizing capacity of frozen boar spermatozoa.

Animals↗