Abstract
BACKGROUND: Cryopreservation is an effective tool for the preservation of live biological materials. OBJECTIVE: This study examined the suitability of cryopreservation protocols and the effectiveness of ultrasound for silver carp embryos. MATERIALS AND METHODS: Embryos at three developmental stages were exposed to 10, 15, 20, and 25% of five cryoprotectants (CPAs), namely propylene glycol (PG), dimethylformamide (DFA), DMSO, Me0H, and ethylene glycol (EG) for 20 min. Embryos were exposed to twelve vitrification solutions (VSs) for 10 (five steps of 2 min), 15 (five steps of 3 min), 20 (five steps of 4 min) min. Embryos were also exposed to ultrasound in VSs prior to cooling for cryopreservation. RESULTS: Hatching rates decreased with increasing CPA concentrations while toxicity varied in the order of PG < DMSO < EG < MeOH < DFA. Tail elongation stage was more tolerant to CPA than 6-somites and morula stages. The survival of embryos exposed to ultrasound in VS was remarkably lower than in water. Embryos exposed to ultrasound in VSs under the best conditions did not response well after attempted vitrification. CONCLUSION: Ultrasound-mediated CPA impregnation could be effective but other innovative methods may be needed to attain successful cryopreservation.