異なる塩分濃度で飼育したウシエビの筋肉と血リンパ中の遊離アミノ酸組成

抄録

The black tiger prawn Penaeus monodon is cultured in barckish water ponds for better growth rate by farmers despite being a marine species. This study on the free amino acid (FAA) variation in the hemolymph and muscle of the prawn in different salinities revealed that the composition of FAA in the hemolymph of 30‰ acclimatized prawns was similar to that in the muscle, indicating this is indeed a physiologically marine-adapted species. The composition of FAA in the muscle from prawns acclimatized to different salinities were similar to each other. The very high concentration of FAA which belong to essential amino acids in the hemolymph of 15‰ acclimatized prawns suggested that these FAA could be more available for tissue to take up at this salinity. Significant amounts of urea were found in the hemolymph of 45‰ acclimatized prawns, suggesting that urea was purposely kept as an inexpensive osmolite. The ability to use urea to adapt to a high salinity environment in invertebrates might have developed long before sharks and rays adapted urea as an osmolite.