| Abstract: | Spinal cord polysomes were prepared from 15-day-old rats, 3-month-old rats, and adult triethyl tin-fed and control rats by a procedure adapted from that of Zomzely -Neurath et al. (1973) for brain polysomes. The state of aggregation and the activity in a cell-free system supplemented with a hepatic enzyme fraction were studied with these preparations. The properties of the amino acid-incorporating system in spinal cord polysomes were similar to those of brain systems with respect to rapid incorporation in the first 30 min of incubation, dependence on polysomes and supplementary enzymes, sensitivity to emetine and high Mg2+, and relative insensitivity to cycloheximide. Polysomes from 15-day-old rats were more highly aggregated than those from 3-month-old rats, but incorporation of radioactive amino acids was not different in the preparations from the two age groups with respect to the requirement for the supplementary enzyme fraction or the kinetics. Spinal cord polysomes prepared from rats with chronic triethyl tin-induced edema and demyelination were slightly more aggregated than those from the controls. Average increases of 30% in amino acid incorporating activity were observed in spinal cord polysomes from triethyl tin-fed rats compared to those of controls. Similar increases have been shown previously in fractions from the spinal cord slice, especially in the myelin fraction (Smith , 1973). Spinal cord polysomes from rats in two stages of development and in different experimentally-caused physiological states behaved differently within the limits of our in vitro system. |
