Fig. 6

Stimulation of caput sperm motility by FKBP12. Caput and corpus sperm were isolated from the epididymal tubules and dispersed in Hank’s balanced salt solution (HBSS) buffered with 15 mM Hepes and 4 mM sodium bicarbonate, and containing 0.2% BSA, 5 mM D-glucose, 10 mM sodium pyruvate, 1 mM nonessential amino acids, and 25 µg/ml soybean trypsin inhibitor. Samples (100 µl) of sperm were treated with 10 nM FKBP12 and videotaped for motility analysis at 15-, 30- and 60-min time points. Videotaped images were digitized and analyzed in real time using a Hamilton Thorne 2000 motility analyzer. After a 15-min incubation with 10 nM FKBP12 (solid bars), caput sperm exhibited double the curvilinear velocity (VCL) of control caput sperm (top panel). A smaller but statistically significant increase was also evident in the path velocity (PATH). The straight line velocity (VSL), straightness (STR), linearity (LIN), beat cross frequency (BCF), and lateral head amplitude (ALH) were not significantly affected by FKBP12. Treatment of the more mature corpus sperm with FKBP12 had no statistically significant effect on their motility parameters compared with control corpus sperm (bottom panel). The treatment of immature caput sperm with FKBP12 stimulated their curvilinear velocity to the level seen in normal corpus sperm. Units presented are as follows: PCT = percent; VSL, PATH, VCL = µM/sec; STR, LIN = ratios; ALH = µM; BCF = 1/sec. Open bars represent vehicle. Error bars represent standard deviations of the mean. The asterisks represent statistical significance.