Propionate-induced sperm chemotaxis. (a) Histogram shows the numbers of spermatozoa recovered in the distal fractions of modified swim-up assays, upon the indicated treatment (50 mM PA, 5 mM AA, or 0,6% BSA as positive control). The number of sperm cells (NT) recovered in the untreated medium is arbitrarily set to 1. Mean ± SD of six independent experiments are shown (n = 6. * = p < 0.05, ** = p < 0.01, *** = p < 0.001, one sample t-test). (b) Histogram shows the kinematic parameters obtained by CASA system, relative to sperm cells recovered in the distal fraction of modified swim-up assays, upon the indicated treatment (50 mM PA). Curvilinear velocity (VCL, µm/s), linearity (LIN, %), straightness (STR, %), straight-line velocity (VSL, µm/s), and average path velocity (VAP, µm/s). The kinematic values of sperm cells (NT) recovered in the untreated medium are arbitrarily set to 1. Mean ± SD of 8 independent experiments are shown (n = 8. * = p < 0.05, ** = p < 0.01, one sample t-test). (c) Histogram shows the kinematic parameters obtained by CASA system, relative to sperm cells recovered in the distal fraction of modified swim-up assays, upon the indicated treatment (5 mM AA). Curvilinear velocity (VCL, µm/s), linearity (LIN, %), straightness (STR, %), straight-line velocity (VSL, µm/s), and average path velocity (VAP, µm/s). The kinematic values of sperm cells (NT) recovered in the untreated medium are arbitrarily set to 1. Mean ± SD of 8 independent experiments are shown (N = 8. * = p < 0.05, ** = p < 0.01, one sample t-test).