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Data presented here showed that the degradation pattern of varying nucleotides in muscle of wrasse, Pseudolabrus japonicas, kept at 0°C somewhat differed from that of carp1). ATP decreased quite rapidly as compared with that in carp muscle. A complete degradation of ATP occured approximately a three-hour period after slaughter, which corresponded to 1/20 to 1/30 of the time required for ATP degradation in carp muscle. While nearly no rigor mortis was detected in carp muscle during the chill-storage1), a quite marked rigor mortis was detected in the wrasse muscle at three-hour period of storage, accompanied with the rapid disappearance of ATP and the accumulation of considerable amount of AMP. Not much difference was noted between wrasse and carp muscle in the time of maintain-ing of maximal amount of IMP. The time of keeping passable flavor-quality was found about a half the time of incipient spoilage.

The stability of tetracyclines in muscle tissue at lower temperatures has been studied by WEISER et1), TARR et al2), WALKER and AYRES3), and TOMIYAMA et al 4-6). No concordant results, however, have been reported so far. The present authors studied on factors governing the stability of CTC in mackerel flesh brei, and revealed that two modes of inactivation were involved, namely, one occurred shortly after the addition of CTC, and the other during storage. It was found that the former could be inhibited by the inclusion of chelating agents and the latter by the presence of antioxidants (Tables 2 and 3). These protective substances, however, did not prevent CTC in a buffered solution from deterioration at 100°C (Fig. 1). It was observed that residual CTC after a 3-day icing appeared to become stabilized (Fig. 2). This apparent increase in the stability seems to be due to either antibacterial activity of oxidized CTC or of oxidized oil per se. Data herein reported made it clear that a disagreement among the works above-cited on the stability of CTC in tissues was resulted from a difference among tissues employed by the above cited authors in their ferric iron content and the rate of oxidation of oil in tissues.

The present paper deals with development of a practical fluorometric method for the determination of chlortetracycline (CTC) and with the reliability of the fluorometric method for CTC assay in ice as compared with several chemical and microbiologic assay methods. Two field fluorometric procedures have been developed in which the visual comparison of the fluorescence of a sample with that of a standard is made by using flat-bottom test tubes, on one hand, and a portable nephelo-colorimeter, on the other, viz., (1) by the use of test tubes: place 10-cc aliquots of supernatent of a thawed sample ice and the standard CTC solution series in a series of the flat-bottom test tubes of 27mm. in diameter, and then add to each test tube lcc. of the alum reagent; after a 5- to 10-minute standing, estimate the CTC concentration of the sample by comparing from top of the tubes the intensity of fluorescence of the sample with each of the standard series while being side-irradiated with a long wave ultra-violet ray lamp, (2) by the use of the portable nephelo-colorimeter: add 1-cc. aliquot of the alum reagent to 10-cc. aliquot of supernatent of a thawed sample ice and a standard CTC solution (4 or 2mcg./cc. depending on CTC content of the sample); after allowing it to stand for 10 minutes, place the sample in one of the comparison tube, a, and the standard in the other tube, b; set the bottom of an inner tube for the tube, b, at a depth of 30mm. and by adjusting the other inner tube find the reading, h, on the tube, a, which will give fluores-cence intensity comparable to that of the standard, both tubes being equally irradiated with the long wave ultra-violet lamp; the content of CTC (mcg./cc.) can be calculated by a formula, S×30/h, where, S, the CTC concentration of the standard solution employed. The feasibility of the fluorometric method for CTC-estimate in ice has been clearly shown by data that, while the fluorometric method gave a comparable value to that obtained by the microbiologic method, higher values were always resulted when assayed by a modified acid colorimetric8), the UPHAM et al's7) and the SAKAGUCHI et al's method9), but lower values by the Japan FDA method6).