Effects of starvation on RNA : DNA ratio, glycogen content, and C : N ratio in columellar muscle of the Japanese turban shell Turbo (Batillus) cornutus (Gastropoda)

ABSTRACT: The validity of using the RNA : DNA ratio, glycogen content, and C : N ratio in the columellar muscle as indicators of the nutritional condition in the Japanese turban shell Turbo cornutus was examined. These biochemical indices were compared between fed and starved animals. The fed animals were fed brown algae to satiation for 108 days as a control, whereas the starved animals were not fed for the first 75 days and then fed for next 33 days. All three indices declined during the starvation period, and the values for the starved group were significantly lower than those for the fed group during days 20–75. At day 108, after the re-feeding period, the indices for the starved group were found to have increased. Among the indices, only the RNA : DNA ratio for the starved males responded rapidly to starved conditions and became significantly lower even at day 4, and only the RNA : DNA ratio for the starved males and females recovered to those levels of the fed animals at day 108. The results indicated that the RNA : DNA ratio is the most rapid indicator of nutritional stress among the three indices. However, it is recommended that glycogen content and C : N ratio be used in addition to the RNA : DNA ratio for monitoring the health of T. cornutus as the RNA : DNA ratio showed large variations.