Studies on the semen biology and sperm cryopreservation in the
sterlet, Acipenser ruthenus L.
F.
Lahnsteiner, B. Berger, A. Horvath, B. Urbanyi-2004
Aquaculture
Research, 35(6):
519-528
Abstract:
The
present study investigated motility, acrosome reaction, fertility and
cryobiological parameters of the semen of the sterlet, Acipenser ruthenus
L. Sperm motility persisted for about 4 min in water, and the main
swimming type was the linear motion. Motility was prolonged at osmolalities
of 12.5 mosmol kg-1 and in the presence of magnesium
ions, while calcium had no effect. Also a pH in the range of 7.0-9.0 had no
effect on ` motility. At osmolalities of 25-50 mosmol kg-1
the sperm motility was partly inhibited, at osmolalities of 100 mosmol kg-1,
completely and irreversibly. In 50 mosmol kg-1
solutions with 2.5-5 mM L-1 KCl the motility inhibition
was total, but reversible. The acrosome reaction was not induced by one of
the described solutions, but the percentage of spermatozoa with reacted
acrosomes was low (<20%) and highly variable in all experiments. The
optimal extender base for cryopreservation was a solution consisting of 50 mM L-1
NaCl, 5 mM L-1 KCl, 10 mM L-1 Tris
(pH 8.5). From the tested cryoprotectants only dimethylsulphoxide (DMSO) and
methanol provided sufficient cryoprotection. After freezing and thawing, the
motility rates and swimming velocities were higher with DMSO than with
methanol. However, the fertility was very significantly reduced with DMSO
(10.3±0.5%) while with methanol fertilization rates in a similar range
(32.7±4.4%) as with fresh semen (33.90±0.8%) could be obtained. Optimal
freezing conditions for sterlet semen were in the vapour of liquid nitrogen
3-5 cm (-95°C to -85°C) above its surface, the optimal thawing conditions at 25°C for 30 s.
The acrosome reaction was not induced by these cryopreservation protocols.
(Institute for Zoology, University of
Salzburg, Hellbrunnerstrasse 34, A-5020 Salzburg, Austria. E-mail: Franz.Lahnsteiner@sbg.ac.at)