To study mechanisms involved in fertility, many experimental assays are conducted by incubating spermatozoa in the presence of molecules dissolved in solvents such as ethanol (EtOH) or dimethyl sulfoxide (DMSO). Although a vehicle control group is usually included in such studies, it does not allow to evaluate the intrinsic effect of the solvent on sperm parameters and its potential influence on the outcome of the experiment. In the present study, we incubated human spermatozoa for 4 h in a capacitation medium in the absence or the presence of different concentrations of EtOH and DMSO (0.1, 0.5, 1.0, and 2.0%) to assess the impact of these solvents on sperm motility, vitality, capacitation, and acrosome integrity. The presence of statistically significant relationships between increasing solvent concentrations and the investigated parameters was assessed using linear mixed models. A significant effect was observed with both solvents for total and progressive sperm motilities. We also evaluated the effect of time for these parameters and showed that the influence of the solvents was stable between 0 and 4 h, indicating an almost direct impact of the solvents. While EtOH did not influence sperm vitality and acrosome integrity, a significant effect of increasing DMSO concentrations was observed for these parameters. Finally, regarding capacitation, measured via phosphotyrosine content, although a dose-dependent effect was observed with both solvents, the statistical analysis did not allow to precisely evaluate the intensity of the effect. Based on the results obtained in the present study, and the corresponding linear mixed models, we calculated the concentration of both solvents which would result in a 5% decline in sperm parameters. For EtOH, these concentrations are 0.9, 0.7, and 0.3% for total motility, progressive motility, and capacitation, respectively, while for DMSO they are 1.5, 1.1, >2, 0.3 and >2% for total motility, progressive motility, vitality, capacitation, and acrosome integrity, respectively. We recommend using solvent concentrations below these values to dissolve molecules used to study sperm function in vitro, to limit side effects.

We examine the impact of implementing active pedagogical methodologies in three successive data science courses for a biology curriculum at the University of Mons, Belgium. Blended learning and flipped classroom approaches were adopted, with an emphasis on project-based biological data analysis. Four successive types of exercises of increasing difficulties were proposed to the students. Tutorials written with the R package learnr were identified as a critical step to transition between theory and the application of the concepts. The cognitive workload needed to complete the learnr tutorials was measured for the three courses and it was only lower for the last course, suggesting students needed a long time to get used to their software environment (R, RStudio and git). Data relative to students' activity, collected primarily from the ongoing assessment, were also used to establish student profiles according to their learning strategies. Several suboptimal strategies were observed and discussed. Finally, the timing of students contributions, and the intensity of teacher-learner interactions related to these contributions were analyzed before, during and after the mandatory distance learning due to the COVID-19 lockdown. A lag phase was visible at the beginning of the first lockdown, but the students' work was not markedly affected during the second lockdown period which lasted much longer.