Mutsuyosi Tsuchimoto

Effects of feeding of β-carotene-supplemented rotifers on survival and lymphocyte proliferation reaction of fish larvae (Japanese parrotfish ( Oplegnathus fasciatus) and Spotted parrotfish(Oplegnathus punctatus)): preliminary trials

Japanese parrotfish (Oplegnathus fasciatus) and Spotted parrotfish(Oplegnathus punctatus) larvae were fed with β-carotene supplemented rotifers or unsupplemented control rotifers for 24 days after hatchout. Results show that survival rates of β-carotene supplemented groups of both Japanese parrotfish and Spotted parrotfish larvae were higher than that of control groups. β-carotene supplemented and unsupplemented control groups exhibited similar growth in both species during this experiment. Proliferation of spleen lymphocytes with 100µg m1−1 of ConA, 10 or 50µg ml−1 of Poke weed mitogen from β-carotene supplemented group was higher than that of a control group of Japanese parrotfish. In Spotted parrotfish treated with 100µg ml−1 of ConA from the β-carotene supplemented groups lymphocytes proliferated to a higher degree than in the control. Results suggest that the supplementation of β-carotene to rotifers, might be of benefit in production of healthy, resistive larvae against infectious disease.

Influence of storage temperatures and killing procedures on post‐mortem changes in the muscle of horse mackerel caught near Nagasaki Prefecture, Japan

The effect of storage temperature (0, 5, 10, and 15°C) and killing procedure (instant, struggled, temperature shocked, and spinal cord destruction killing) on post-mortem changes in the muscle of the horse mackerel caught near Nagasaki, Japan, was investigated. Temporal changes in adenosine triphosphate (ATP), inosine monophosphate (IMP), and lactic acid concentrations were slowest at 10°C storage temperature. The increase in K-values was slower at 10°C and below than at 15°C storage temperature. In addition, 10°C storage temperature was most suitable for maintaining a constant breaking strength value of the muscle. Regarding the effect of killing procedure, temporal changes in ATP, IMP, and lactic acid concentrations were slowest then killed by spinal cord destruction. The increase in K-value and the decrease in breaking strength were also slowest in the spinal cord destruction group. From these results, it was considered that storage at 10°C temperature and spinal cord destruction killing procedure were most effective in delaying post-mortem change in the horse mackerel.

Comparison of 5'-inosine monophosphate and p-nitrophenyl phosphate degrading activities among red, pink, and white muscle fibers of cultured carp

As part of a study to clarify the differences in the temporal change in K-value among fish species, the temporal change in K-value and the 5′-inosine monophosphate (5′-IMP) and p-nitrophenol phosphate (p-NPP) degracling activities in the red, pink, and white muscle fibers in the dorsal muscle of the carp were compared. The temporal change in K-value was fastest in red, followed by pink, and white muscle fibers, at both 0°C and 32°C. Moreover, the 5′-IMP and p-NPP degrading activities were highest in red, followed by pink, and white muscle fibers at near optimum pH concentrations. The 5′-IMP degrading activity at pH 7.0 had a positive correlation with the increasing rate of K-values at 32°C for all types of muscle fibers. These results suggest that differences in increasing rates of K-values between red, pink, and white muscle fibers corresponded to the 5′-IMP degrading activities.

The influence of thermal acclimation on fragmentation of myofibrils from carp stored at different temperatures

10℃(L群)と30℃(H群)に飼育したコイを用い,各保存温度下(0,15,30℃)の筋原線維の小片化を検討したところ,いずれの保存温度でもH>Lの傾向にあった。この差異に影響する要因を次に検討した。筋収縮率は30℃保存ではH Lであった。カルパイン活性は25℃と30℃反応ではH>L,20℃からO℃反応ではH≦Lであった。筋小胞体のCa-ATPase活性は30°CからO°C反応までH<Lであった。両群の筋原線維小片化の差異には,これらの要因の関与が推察された。

Influence of Body Protein Content on Deviation of Fish Body Density in Cultured Red Sea Bream.

To clarify the influence of body composition on the deviation of fish body density in cultured red sea bream, the contents of fat, water, protein, and ash in whole body were analyzed after measuring the body density of living fish in 39 specimens of cultured and wild fish. A significant, negative correlation was found between the fish body density and the body fat content, and a significant, positive correlation was found between the deviation of fish body density from the regression line and the density of remaining matter, without fat and water from whole body. On the other hand, a significant, negative correlation was found between the density of remaining matter and the body protein content though no significant correlation was found between that of remaining matter and body ash content. Therefore, it is suggested that the deviation of fish body density from the regression line between the fish body density and the body fat content is caused by the body protein content, or muscle quantity, in the whole body.

Studies on freshness of trawl catches - II. Freshness of trawl-caught fish at fishing ports and retail markets in Thailand.

To clarify the actual situation of freshness of fish at landing plates of Thailand and its change during transportation and marketing, we measured K values of trawl-caught fish at fishing ports and retail markets in four major fishing ports of Thailand, Phuket, Paknam, Songkhla, and Bangkok. The mean K values just after landing differed by fishing ports; we obtained 39.4% at Songkhla, 34.3% at Paknam, and 36.2% at Bangkok, contrasting with a significantly low value of 26.0% at Phuket. The last-named is located on the Andaman Sea side, while others are on the Gulf of Thailand. Levels of K values also fluctuated from boat to boat. Fish landed by fishing boats operating in the Gulf of Thailand which stayed more days at sea for a cruise than fishing boats operating in the Andaman Sea, showed higher K values. The mean K values of fish landed by fishing boat were found to be in a positive correlation with days at sea of the boat, increasing at a rate of 2.2% per day at sea. The mean K values observed at retail markets were 52.3% in Paknam facing the Gulf of Thailand which was significantly higher than 29.0% observed in Phuket located on the Andaman Sea side. Increase in K values during transportation and marketing, from landing to consumers, was revealed to be at a rate of 0.9 to 1.5% per hour. Taking into consideration the high environ-mental air temperature of the tropical country, the rate mentioned above was rather very low. Early progress of bacterial contamination of fish caught in Thailand was suggested by the rise in pH when K values were comparatively low.