Gilbert Vassart

Simulation of polyribosome disaggregation

Abstract Deterministic and stochastic models for polyribosome breakdown into monosomes are developed simulating two situations. 1. (i) Polyribosome degradation by ribonuclease 2. (ii) Polyribosome degradation by mechanical forces. Another model is developed simulating the modification of polyribosome distribution in acellular protein synthesis systems in the absence of significant initiation. The hypothetical mechanisms of these three phenomena are discussed in light of the comparison between the results of the simulations and experimental data available in the literature.

Improved Techniques for the isolation of intact Thyroglobulin-Synthesizing Polysomes

Abstract A method is presented, based on the use of an extraction buffer containing 200 m m Tris-HCl, pH 8.5, which permits the isolation in high yield of apparently undegraded polysomes from beef thyroid. Upon treatment with detergent, both the 800 g pellet and the 27,000 g pellet yield polysome profiles exhibiting very few monosomes and small polysomes but a major, homogenous peak of very large, thyroglobulin-synthesizing polysomes. No such large polysomes were evident in gradients of free polysomes. The polysomal nature of this peak of very large polysomes was verified by treatment with detergent and ribonuclease, by electron microscopy, and by extraction of the mRNA.