Motility analysis and energetics of the Siberian sturgeon Acipenser baerii spermatozoa

A study of motility was carried out on spermatozoa of the Siberian sturgeon (Acipenser baerii Brandt) reared at the Cemagref experimental research station, St Seurin sur l'Isle, France. About 90% spermatozoa are activated within a few seconds after a double step dilution (final dilution 1/600) and the number of motile cells declines regularly to 10-20% after 2 mn. During the same period of time, the flagellum beat frequency remains stable at about 50 Hz for 30 sec and drops to 30 Hz after 60 sec. A morphological analysis of the movement of the flagellum shows that during the first 20 sec, waves are distributed on the entire length of the flagellum; later, they disappear progressively from the distal part within 1 mn in the case of 90% of the spermatozoa. Finally after 2 mn, most of the flagella are straight and devoid of wave. The ATP content declines very rapidly after activation from 7.58 +/- 1.85 to 4.05 +/- 1.51 nmol/108 spermatozoa within 5 sec (P=0.004). Spermatozoa left in the genital tract of the males over a period of 24 hrs (in vivo survival) do not show significant change in the percentage of motile cells (82 +/- 14 vs 74 +/- 15) nor in the ATP content (6.13 +/- 2.37 vs 4.59 +/- 1.42 nmoles/108 spermatozoa). An aliquot of these spermatozoa stripped from testis and stored during the same period of 24 hrs at 4 degrees C shows a significant decrease in the percentage of motile cells from 82 +/- 14 to 59 +/- 30 (P<0.01) and in the ATP content from 6.15 +/- 2.4 to 1.95 +/- 1.37 nmoles/108 spermatozoa (P=0.001).