The hatching of common carp (Cyprinus carpio L.) embryos in response to exposure to different concentrations of cryoprotectant at low temperatures

The hatching performance of embryos of the common carp (Cyprinus carpio L.) was examined after 1, 7, 14, 21, or 28 days of storage at -8, -6, -4, -2, 0, 2, or 4degreesC with different concentrations of methanol (0.5-7.0 M in 0.5 M steps) or varying concentrations of methanol in 0.1 M sucrose or trehalose. Preserved embryos failed to hatch after storage at -8 and -6degreesC,regardless of the duration of storage or the concentrations tested. Likewise, there was no hatching out above 5.0 M concentration of methanol, even with the addition of sucrose or trehalose. After storage at 2 or 4 degreesC, the hatching rate was higher with mixtures of methanol (1.5 M) and trehalose (0.1 M) than with methanol plus sucrose or methanol alone. At 4 degreesC, the solution containing 1.5 M methanol supplemented with trehalose gave the highest hatching response of embryos stored for 14 days. Comparison of hatching after 24 h of storage at the effective temperatures (-4, -2, 0, 2, and 4degreesC) revealed that low concentrations of methanol were effective at high temperatures and high concentrations at sub-zero temperatures. The combination of 0.1 M trehalose with 1.5 M methanol gave the highest percentage hatching out both at 4 and 2degreesC. At 0degreesC, the highest percentage hatching occurred with 0.1 M trehalose plus 2.5 M methanol and at -2 and 4 degreesC, the best results were with 0.1 M trehalose plus 3.0 M methanol. (C) 2002 Elsevier Science (USA). All rights reserved.