Figure 4. Effects of hydroxylamine and light on human sperm thermotaxis.

(a) Effect of hydroxylamine on sperm thermotaxis, as reflected in the relative accumulation in the warmer compartment. Prior to thermoseparation, the spermatozoa were incubated with hydroxylamine (5 mM) for 30 min at room temperature in the dark (black column) or under illumination (white/color columns). The plus or minus signs above the columns stand for whether or not the indicated opsin absorbs at the wavelength of the illumination ( ≥ 25% of the absorbance at its peak). Each experimental result is the mean ± SEM of 5–9 determinations. The positive control, defined as 1, is the sperm accumulation in the absence of hydroxylamine in the dark [being almost the same in each set of experiments, (140 ± 8)×10⁴cells/ml (mean ± SEM of 5–12 determinations)]. *P (relative to the positive control in the dark) and **P (light versus dark in each wavelength in the presence of hydroxylamine) < 0.03 according to two-way ANOVA. The no-gradient accumulation was (1.6 ± 0.2)×10⁴cells/ml independently of whether hydroxylamine was present or not. (b) Effect of illumination on thermotaxis in the absence of hydroxylamine. Spermatozoa were incubated for 30 min at room temperature in the dark or under illumination at the indicated wavelength prior to thermoseparation. Each experimental result is the mean ± SEM of 7–10 determinations. The dark control was defined as 1 [(141 ± 8)×10⁴ cells/ml (5–13 determinations)]. The results were not significantly different from the control (two-way ANOVA).