SUMMARY The influence of feeding, activity and pasteurizing doses of gamma irradiation on the nucleotide composition and breakdown in English sole (Parophrys vetulus) was studied. Feeding did not cause any significant change in the total amount of nucleotides. Active fish had lower amounts of ATP and increased levels of IMP, but this difference was not significant after they had been stored 7 days in ice. In contrast to the results reported for other species of sole, inosine was present in English sole after 7 days in ice. Irradiation, 0.5 and 1.0 Mrad, did not affect the changes in the nucleoside and nucleotide composition.

sine, phenylalanine, and ornithine. In this connection it is interesting to note that the average weight of the liver between 150 and 175 days only increased 1.3%. An increase in free amino acid concentration during this period could be explained by a general increase in metabolic activity and enzyme maturation. A decrease in concentrations of the TCA cycle related amino acids, glutamic acid and aspartic acid, may be related to the sharp increase in demand for energy, but no proof is available. Correlation between free amino acid concentrations in the brain and the liver of fetal monkeys is virtually absent. The four amino acids whose concentrations increase in the brain during fetal development do not show this trend in the liver. On the contrary, while the concentrations of aspartic acid and glutamine increase in the brain, they decrease in the liver. Glutamic acid levels in the brain and the liver showed the same sharp increase shortly after birth. The concentrations of threonine, proline, and alanine decrease both in brain and liver.The free amino acid content of umbilical cord serum from the same fetal monkeys (1) failed to correlate with our data on the brain and liver amino acid concentrations. The free amino acid pool available during develop-ment of the fetus is undoubtedly a reflection of the free amino acid concentration in the plasma of the mother ( 6 ) , but the influence of fasting of the mother monkeys for 8 hr prior to surgery on the amin? acid levels in the organs of the fetus is unknown.It is however, difficult to conceive that the wide range of values for some amino acids are due to dietary influences. Although all animals in this study were growing at the same rate despite the differences in free amino acid concentrations, it is doubtful that these levels in the organs of the fetus are a proper reflection of the rate of protein synthesis at the cellular level.

No abstract

SUMMARY The formation of volatile bases and volatile acids during heat processing of albacore tuna loin sections was studied, using a closed system swept with nitrogen gas. The cell containing the tuna was heated gradually to 100°C, and the volatile acids and bases were trapped in standardized solutions. During the first 80 min of heating, at precooking temperatures, volatile acid evolved exceeded by threefold the slight amounts of volatile base (less than 0.5 mcq per 1000 g). Later during the heating cycle equal amounts of volatile acids and bases were formed. The ratio of sulfur to iron responded directly to the initial vacuum present in canned tuna. At high vacuum the ratio was 0.575. Sulfur was absent from the black deposits when the cans were sealed without evacuation, even when high levels of cystine were added. In commercially packed shrimp the sulfur to iron ratio was 0.322, which is consistent with a deposit of mixed oxides of iron, combined with ferrous sulfide. Addition of acetic acid (a volatile acid) at 10 mM per can suppressed the formation of black deposits at all closing vacuums in a model system containing added cysteine, while the addition of ammonium hydroxide (volatile base) or no addition resulted in the formation of black deposits at 26 inches Hg of closing vacuum.

SUMMARY: The concentration of nucleotides was lower in the adductor muscle of the oyster (1.64 μmoles/g) than in the remaining dark tissues of the oyster (2.75 μmoles/g). The concentration was less in the whole oyster meats (2.87 μmoles/g) than is usually found in fish muscle, or other marine invertebrates. In addition to the adenine nucleotides and inosine monophosphate, uridine triphosphate, guanosine triphosphate, guanosine diphosphate, guanosine monophosphate and guanosine diphosphate‐mannose were found in the fresh oysters. Samples collected in summer had greater concentrations of nucleotides than similar winter samples. lnosine monophosphate formed rapidly from adenosine triphosphate during storage at 0°–2°C, while the turnover rate of inosine monophosphate was slow and reflected low 5′‐nucleotidase activity. Hypoxanthine, inosine, guanosine, guanine and uracil were formed during ice storage. The nucleotide breakdown in oysters was not changed by 2 mrads of radiation dose. Total nucleosides and free bases increased during storage of both unirradiated and irradiated samples. During the latter part of the storage period the concentrations of nucleosides and free bases were considerably greater in the irradiated samples. This difference probably is due to the utilization of these compounds by bacteria in the un‐irradiated samples. After 15 days of storage bacteria had increased to more than 10’organisms per g, while the counts for irradiated samples were very low (less than 103 per g).