Protein Synthesis in Imbibed Seeds. Ii. Polysome Formation during Imbibition.

Ribosomes prepared from dry wheat embryos or peanut cotyledons show little or no capacity to incorporate 14C-amino acids into protein. In contrast, preparations from imbibed embryos or cotyledons are active (1). In the presence of polyuridylic acid, the ribosome system of dry seed is as active as that from imbibed seed in catalyzing 14C-phenylalanine incorporation (1). These results suggested the formation or activation of messenger ribonucleic acid during imbibition. Since considerable evidence, with bacterial and mammalian systems (Z-5), has implicated polysomes as the primary sites of protein synthesis, t appeared desirable to investigate this feature of the seed ribosome, particularly in relation to imbibition. The results of such a study are reported herein. In addition, details of the characteristics of the incorporating systems are also presented.