María Elena Trujillo Ortega

Boar spermatozoa cryopreservation in low glycerol/trehalose enriched freezing media improves cellular integrity ☆

The use of glycerol for boar semen cryopreservation results in low fertility, possibly due to toxicity. This has led to recommend the use of solutions with less than 4% glycerol. Trehalose is a disaccharide known to stabilize proteins and biologic membranes during processes such as cryopreservation. Thus, it was decided to evaluate the cryoprotective effect of glycerol/trehalose mixtures. Effects on motility (M), viability (Vb) and acrosomal integrity (nA) were evaluated. Sperm samples were frozen in three different extenders: G4 contained 4% glycerol; T1 contained 1% glycerol plus 250 mM trehalose and T0.5 was constituted by 0.5% glycerol plus 250 mM trehalose. All extenders yielded similar post-freezing/thawing motility rates. Viability was diminished in T0.5 as compared to the others. In regard to acrosome integrity, it was twice as high (P<0.05) in the trehalose enriched media as in G4, the glycerol-only extender. Thus, T1 twice as many spermatozoa were alive, motile and intact, than in either T0.5 or G4, i.e. during freeze/thawing the use of T1 resulted in twice as many fertile cells as when using the other extenders. During our study, we noted that there were wide individual variations both in sperm viability and in motility.

Glycerol decreases the integrity of the perinuclear theca in boar sperm

We evaluated the effect of glycerol on the perinuclear theca (PT) of boar sperm. Samples from six ejaculates obtained from three different boars were incubated in the detergent Brij 36-T. Spermatozoa were treated with a glycerol concentration of either 2 or 4%, and incubated for 10 or 30 min; two other samples were treated with protease inhibitors (PI; leupeptin or an inhibitor commercial cocktail), mixed with 4% glycerol, and incubated for 30 min. A third glycerol-free group was used as the control. The samples were processed for electron microscopy evaluation. The PT remained intact in 78% of the control samples while, after addition of glycerol for 30 min, the proportion of spermatozoa with disrupted or absent PT increased (P < 0.05). PT was preserved in PI samples, but PT changes increased (P < 0.05). Differences due to treatment with glycerol (2 or 4%) at 10 or 30 min were not observed. These results show, to our knowledge for the first time, the adverse effect of glycerol on the integrity of the PT.

Identification and genotyping of porcine circovirus type II (PCV2) in Mexico

Porcine circovirus type 2 (PCV2), family Circoviridae, genus Circovirus infection in domestic pig has been associated with several pathological conditions being the most important of them the postweaning multisystemic wasting syndrome. Many studies have demonstrated the existence of three PCV2 genotypes (a, b, and c) and recently PCV3. Until now, these genotypes or subgenotypes have not been described in Mexico. We found genetic changes in ORF2 from nine strains of PCV2 obtained from samples of Jalisco, Veracruz, Estado de México, Hidalgo and Sonora states of Mexico. Our results shown the presence of two genotypes (PCV2a and PCV2b) as well as, the presence and differences between the reported subgenotypes. The subgenotype PCV2b (1A/1B, 1A) has a higher prevalence (87.5%) in comparison with PCV2a (2C) (12.5%).