Computer-assisted sperm analysis (CASA): capabilities and potential developments.

Virions of porcine reproductive and respiratory syndrome virus (PRRSV) contain six membrane proteins: the major proteins GP 5 and M and the minor proteins GP 2a , E, GP 3 , and GP 4 . Here, we studied the envelope protein requirements for PRRSV particle formation and infectivity using full-length cDNA clones in which the genes encoding the membrane proteins were disrupted by site-directed mutagenesis. By transfection of RNAs transcribed from these cDNAs into BHK-21 cells and analysis of the culture medium using ultracentrifugation, radioimmunoprecipitation, and real-time reverse transcription-PCR, we observed that the production of viral particles is dependent on both major envelope proteins; no particles were released when either the GP 5 or the M protein was absent. In contrast, particle production was not dependent on the minor envelope proteins. Remarkably, in the absence of any one of the latter proteins, the incorporation of all other minor envelope proteins was affected, indicating that these proteins interact with each other and are assembled into virions as a multimeric complex. Independent evidence for such complexes was obtained by coexpression of the minor envelope proteins in BHK-21 cells using a Semliki Forest virus expression system. By analyzing the maturation of their N-linked oligosaccharides, we found that the glycoproteins were each retained in the endoplasmic reticulum unless expressed together, in which case they were collectively transported through the Golgi complex to the plasma membrane and were even detected in the extracellular medium. As the PRRSV particles lacking the minor envelope proteins are not infectious, we hypothesize that the virion surface structures formed by these proteins function in viral entry by mediating receptor binding and/or virus-cell fusion.

/pdf/envelope-protein-requirements-for-the-assembly-of-infectious-51is0q2sdo.pdf

Envelope protein requirements for the assembly of infectious virions of porcine reproductive and respiratory syndrome virus

The relationship between stallion fertility and oxidative stress remains poorly understood. The purpose of this study was to identify criteria for thoroughbred fertility assessment by performing a logistical regression analysis using "dismount" sperm parameters as predictors and weekly per-cycle conception rate as the dependent variable. Paradoxically, positive relationships between fertility and oxidative stress were revealed, such that samples that produced pregnancies exhibited higher rates of 8-hydroxy-2'-deoxyguanosine release (1490.2% vs. 705.5 pg/ml/24 h) and lower vitality (60.5% vs. 69.6%) and acrosome integrity (40.2% vs. 50.1%) than those that did not. We hypothesized that the most fertile spermatozoa exhibited the highest levels of oxidative phosphorylation (OXPHOS), with oxidative stress simply being a by-product of intense mitochondrial activity. Accordingly, an experiment to investigate the relationship between oxidative stress and motility was conducted and revealed positive correlations between mitochondrial ROS and total motility (R² = 0.90), rapid motility (R² = 0.89), average path velocity (VAP; R² = 0.59), and curvilinear velocity (VCL; R² = 0.66). Similarly, lipid peroxidation was positively correlated with total motility (R² = 0.46), rapid motility (R² = 0.51), average path velocity (R² = 0.62), and VCL (R² = 0.56), supporting the aforementioned hypothesis. The relative importance of OXPHOS in supporting the motility of equine spermatozoa was contrasted with human spermatozoa, which primarily utilize glycolysis. In this study, mitochondrial inhibition significantly reduced the velocity (P < 0.01) and ATP (P < 0.05) content of equine, but not human, spermatozoa, emphasizing the former's relative dependence on OXPHOS. The equine is the first mammal in which such a positive relationship between oxidative stress and functionality has been observed, with implications for the management of stallion fertility in vitro and in vivo.

The Paradoxical Relationship Between Stallion Fertility and Oxidative Stress

Artificial insemination in pigs today

Sperm quality is often evaluated through computer-assisted semen analysis (CASA) and is an indicator of boar fertility. The aim of this research was to study the relationship between CASA motility parameters and fertility results in pigs. Insemination records and semen parameters from a total of 45,532 ejaculates collected over a 3-yr period were used. The statistical model for analysis of fertility data from these inseminations included factors related to sow productivity. The boar- and semen-related variance (direct boar effect) were corrected for the effects of individual boar, genetic line of the boar, age of the boar, days between ejaculations, number of sperm cells in an ejaculate, number of sperm cells in an insemination dose, and AI station. The remaining variance was analyzed if semen motility parameters had a significant effect. This analysis revealed significant (P 0.05) were observed between effects of AI stations on fertility outcome, underscoring the objectivity of the CASA system used. Motility parameters can be measured with CASA to assess sperm motility in an objective manner. On the basis of the motility pattern, CASA enables one to discriminate between the fertilizing capacity of ejaculates, although this depends on the genetic line of the boar used in AI stations.

Application of computer-assisted semen analysis to explain variations in pig fertility.

Efficient production of high quality semen is of major importance to artificial insemination (AI) organizations. The semen produced should be free of contagious organisms, be of high quality, have good storage properties, fertilizing capacity and be of high genetic value. The best approach to prevent the spreading of microorganisms via semen in the process of AI is to collect semen from boars free from specific diseases, for example pseudorabies virus or leptospirosis. Antibiotics are added to the semen to suppress proliferation of microorganisms or even reduce their number. Sperm production is influenced by many factors such as season, collection frequency, breed and age. The average number of sperm cells produced per boar per week can vary more than 30% within one AI station, depending on the breed. Boar selection and boar management markedly influence the efficiency of sperm production. Sperm quality should be evaluated by fertility results obtained at breeding farms related to both farrowing rate and litter size to ensure a good quality monitoring system. A quality control system should be established to provide maximum reliability to customers.

Optimizing semen production for artificial insemination in swine.

The value of microscopic semen motility assessment at collection for a commercial artificial insemination center, a retrospective study on factors explaining variation in pig fertility

H. Feitsma

Papers

Application of computer-assisted semen analysis to explain variations in pig fertility.

Optimizing semen production for artificial insemination in swine.

The value of microscopic semen motility assessment at collection for a commercial artificial insemination center, a retrospective study on factors explaining variation in pig fertility

Reproductive performance of second parity sows: Relations with subsequent reproduction

Additional value of computer assisted semen analysis (CASA) compared to conventional motility assessments in pig artificial insemination.