Four semen samples, respectively, were used in each
species. Two microliter of the sperm suspension
(P. fluviatilis) or of the prediluted semen (S. aurata)
were incubated in 200 ll of the appropriate motilityinhibiting
saline solution or in motility-inhibiting
saline solution containing the different amino acids
listed below for 48 h at 4C and at a cell density of
2–3 9 107 cells/ml. Preliminary experiments indicated
that a 48-h incubation period was most
discriminate to detect the effects of amino acids.
After 24 h, the sperm motility was high in all