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We made a comparative study on changes of ultrastructure and cytochemical Mg2+-adenosine triphosphatase (Mg2+-ATPase) in ordinary muscle of cultured and wild red sea bream during storage in ice.Degeneration of the Z lines of ordinary muscle was faster in cultured fish than in wild fish. In cultured fish, the structure of the Z lines became discontinuous within 1 day in ice. While, the Z lines showed continuity until day 3 in wild fish. Degenerations of other organella, such as the sarcoplasmic reticulum, mitochondria, A band, and I band were similar in both cultured and wild fish.Mg2+-ATPase activity was found at the sarcoplasmic reticulum, near both ends of A band, mitochondria, and nuclear membrane in both fish immediatedly after death. Mg2+-ATPase ac tivity in these organella became undetectable on day 5 in cultured fish, but it was still weakly de tected on day 7 in wild fish.These results suggested that ultrastructure and cytochemical Mg2+-ATPase activity are good indicators for post-mortem changes in fish muscle.

The separation and the quantitative analysis of ATP, ADP, AMP, IMP, inosine and hypo xanthine in the fish muscle were made using the high-performance liquid chromatography with the reversed-phase column.All the ATP related compounds as well as most of the other nucleic acid related compound could be eluted under the phosphate buffer (0.05M-KH2PO4: 0.05M-K2HPO4=1:1) at pH6.78 with the reasonable resolution and the retention time. For the ATP related compounds in the extract of fish muscle, the recovery and the reproducibility by this method were satisfactory and the values obtained agreed with those prepared by the general purpose method of ion exchange chro matography.

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