A step towards using the semen of the common pandora Pagellus erythrinus for practical applications of cryo-research: The computer-assessed sperm motility pattern in long-term cryostored samples

The implementation of gamete cryobanking in aquaculture may improve hatchery practices such as assisted reproduction and genetic selection of desired strains. This paper preliminarily investigated the technical feasibility of cryobanking semen of the common pandora Pagellus erythrinus, an important fishery resource in the Mediterranean area and a promising species for the diversification of productions. Post-thawing motility was evaluated in common pandora semen samples cryopreserved according to eight previously selected protocols and stored in liquid nitrogen for eight years. In order to mimic the practical use of long-term cryostored semen samples, the proportion of living sperm in which motility could be activated was evaluated, by computer-assisted analysis, on thawing and after 3 h of post-thawing incubation at 18 degrees C as biomarker of sperm viability. The assessed parameters were percentage of motile spermatozoa (TM), curvilinear velocity (VCL), lateral head displacement (ALH), beat-cross frequency (BCF) and dance (DNC).The cryostored sperm of the common pandora proved to have promising features. In fact, percentages of motile sperm higher than 40% were always obtained on thawing; moreover, the semen retained its activation ability in the times after thawing, showing no or slight alterations in the motility profile also when activated after 3 h of post-thawing incubation. The best post-thawing performances were recorded with the EG5%-based extender under the F1 curve (equilibration at 2 degrees C; freezing from +2 degrees C to -70 degrees C at 3.8 degrees C/min), that showed the highest percentages of motile cells (80 +/- 3) and no significant alterations in any of the evaluated motility parameters, followed by the EG10% based extender under the F2 curve (equilibration/cooling from 20 degrees C to 2 degrees C at 1 degrees C/min; freezing from +2 degrees C to -150 degrees C at 23.3 degrees C/min).