Absorption, distribution and fate of cobalt in the germ free silkworm, Bombyx mori

Abstract

The amount of Co was measured distributing in tissues or organs of silkworms reared aseptically on an artificial feed or reared from hatching to the 6th day of the 5th instar on an artificial feed containing 50ppm Co, and at the same time the amount of Co excreted into the feces and the amount transported into the pupa were determined. With silkworms reared on an artificial feed containing 36% mulberry leaf powder or those reared from hatching to the 6th day of the 5th instar on an artificial feed containing 50ppm Co, the distribution of Co per 1 gram dry weight of tissue or organ and that per individual were calculated. When 50ppm Co was administered continuously, the amount of Co excreted into the feces was increased immediately after being transferred to a Co-free feed, and decreased with time, mostly excreted in 48hr. In the pupa obtained with the artificial diet alone, the Co amount was 3.14μg, but in the pupa obtained with a diet containing 50ppm Co throughout, the concentration of Co scarcely increased.