EFFECTS OF ION CONTENT AND PH OF MEDIUM ON MOTILITY OF TILAPIA (OREOCHROMIS NILOTICUS) SPERM

PRAPAPORN UTARABHAND AND VICHAI WATANAKUL

ABSTRACT: The motility of tilapia sperm was found to vary depending on the ionic composition and pH of the diluting solutions. Artificial freshwater at pH 7.0 was the best medium for maintaining both the duration and capacity of sperm motility. Concentration of Na⁺(1.5 mM), K⁺ (0.5 mM), Ca²⁺(1.0 mM) and Mg²⁺ (0.5 mM), the same as those of artificial freshwater, activated the motility maximally. Permeabilized tilapia sperm lost functional motility which was maximally restored in the presence of 1 mM ATP. Ouabain, sodium vanadate and 1-fluoro-2,4-dinitrobenzene (FDNB) were shown to inhibit the flagellar beating with K_0.5 values of 1.3 mM, 25 M and 1.6 M, respectively. Conversely, 1-methyl-3-isobutylxanthine activated flagellar beating with K_0.5 of 0.24 mM. Inhibition of Na⁺/K⁺-ATPase activity by ouabain, inhibition of dynein ATPase activity by sodium vanadate, inhibition of creatine kinase activity by FDNB and inhibition of phosphodiesterase activity by 1-methyl-3-isobutyl-xanthine were found to have K_0.5 values of 1.6 mM, 25 M, 1.8 M and 0.20 mM, respectively. These values were close to those for the inhibition of the flagellar beating. Thus, an involvement of Na⁺/K⁺-ATPase, dynein ATPase, creatine kinase and phosphodiesterase in the motility of tilapia sperm is revealed.

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Department of Biochemistry, Faculty of Science, Prince ofSongkla University, Hat Yai, Songkla 90112, Thailand, and
Songkla Coastal Aquaculture Development Center, Songkla. 90000, Thailand.

Received May 1, 1997