Quantities and Activities of Ribosomes in Posterior Silk Glands of the Normal and Nd Silkworms

Abstract

Two ribosomal fractions were prepared from the posterior silk glands of the norml and Nd mutant silkworms. The amounts of two ribosomal fractions of the Nd silkworm were reduced to 4.4 and 5.8%, respectively, of the normal one. The amino acid incorporation activity of the Nd cell-free system containing two ribosomal fractions corresponded to 15 and 13%, respectively, of the normal cell-free system containing the identical fraction. The reduced activity of the Nd cell-free system was mainly ascribable to ribosomes including endogenous mRNA.