Abstract
The amount of nickel (Ni) per 1 gram dry weight of each tissue and organ and that per individual were measured in silkworms reared aseptically on an artificial diet (germ-free silkworms) and in those fed a diet containing 250ppm Ni continuously from the day of hatching to the 6th day of the 5th inster.
The amount of Ni excreted into the feces of the silkworms fed a diet containing 250ppm Ni continuously from the day of hatching to the 2nd day of the 5th instar was examined every 24hrs up to the 96th hr, starting immediately after the replacement of the diet with the Ni-free one. The largest amount of Ni was excreted into the feces immediately after the replacement of the diet with the Ni-free one, being about 24 times that excreted by the control silkworms. After 48hrs, the amount was similar to the control value. Thus, the Ni ingested during continuous oral feeding on 250ppm Ni was excreted into the feces by the 48th hr after feeding.
The amount of Ni contained in the pupa of the germ-free silkworms was 4.57μg on the 2nd day after pupation, while that in the pupae of the silkworms fed a diet containing 250ppm Ni during their larval stage increased moderately to 6.17μg.
