Hatching of common carp (Cyprinus carpio L.) embryos stored at 4 and -2 degrees C in different concentrations of methanol and sucrose.

The hatching performance of common carp (Cyprinus carpio L.) embryos was examined after 12-72-h storage at 4 and -2 degrees C using different concentrations of sucrose (0.1, 0.25, 0.5 and 1.0 M or 3.42, 8.55, 17.10 and 34.2%), methanol (MeOH) (0.5, 1.0, 1.5, 2.0, 2.5, 3.0 and 3.5 M or 1.6, 3.2, 4.8, 6.4, 8.0, 9.6 and 11.2%), or varying concentrations of methanol in 0.5 M (17.10%) sucrose. For sucrose, 0.5 M (17.10%) showed the maximum survival (41+/-1% (12 h) to 11+/-1.5% (72 h)) at 4 degrees C. No survival was observed at -2 degrees C with any concentration of sucrose. At both temperatures employed, hatching was higher with mixed combination of methanol (1.5 M or 4.8%) and 0.5 M (17.10%) sucrose (4 degrees C: 41+/-1.5% (12 h), 38+/-1.2% (72 h); -2 degrees C: 33+/-1.7% (12 h), 28+/-1.2% (72 h)) compared to methanol alone (4 degrees C: 38+/-1.5% (12 h), 35+/-2.5% (72 h); -2 degrees C: 31+/-2.5% (12 h), 25+/-2% (72 h)). The combination of 1.5 M (4.8%) methanol and 0.5 M (17.10%) sucrose produced the best results among all the concentrations tested at both temperatures.

Stage-dependent hatching responses of rohu (Labeo rohita) embryos to different concentrations of cryoprotectants and temperatures.

Hatching performances of three embryonic stages of postfertilization rohu (Labeo rohita) (9-, 12-, and 15-h) were examined after treatment with various concentrations (0.5-4.5M) of two cryoprotectants (methanol and propylene glycol) supplemented with 0.1M trehalose. Different lengths of storage (1-48 h) and temperature (-4 degrees C to ambient) were studied. Of the three stages of embryonic development, the 12-h stage proved to be the most suitable stage for low temperature storage, showing the highest percentage of hatch out (72+/-2%) with 2.0M methanol and 0.1M trehalose. Methanol was more useful for storage at higher temperatures and propylene glycol at subzero temperatures. The maximum possible duration of effective storage of 12-h embryos was 31h in 2.0M methanol at 0 degrees C. No hatch out was found beyond 31h of storage with all concentrations of methanol at 0 degrees C. The results of interactions was that the optimal concentration of methanol was 3.0M at 4 degrees C, 2.0M at 0 degrees C, and 1.5M at 4 degrees C. Among three embryonic stages 12-h stage showed better results in trehalose treatment than sucrose. Among all concentrations of trehalose tested 0.1M gave the maximal survival rate of the rohu embryos.

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 4 degrees C 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 -6 degrees C, 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 degrees C, 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 degrees C, 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 24h of storage at the effective temperatures (-4, -2, 0, 2, and 4 degrees C) 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 2 degrees C. At 0 degrees C, the highest percentage hatching occurred with 0.1 M trehalose plus 2.5 M methanol and at -2 and 4 degrees C, the best results were with 0.1 M trehalose plus 3.0 M methanol.