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Complete suppression of polyadenylation of nuclear precursors of rat brain mRNA by cordycepin leads to degradation of some translatable sequences of both poly(A)(+)- and poly(A)- pre-mRNA localized in 80S hnRNP-particles. This fact has been established by comparative analysis of the data of two-dimensional gel-electrophoretic mapping of translation products synthesized in reticulocytic cell-free system using the exogenous purified templates of rapidly labelling translatable 9-17S hn RNA (pre-mRNA) isolated from brain 80S hn RNP particles of experimental (4 hrs after cordycepin injection) and control (injection of physiological solution) adult healthy male rats. Long contact of brain cells with cordycepin (4 or more hrs) creates conditions for formation of hnRNP-particles devoid of poly(A)+ RNA and poly(A)-binding proteins. These particles differ from "normal" ones by the value of the RNA/protein ratio, and by considerably lower resistance to the action of exogenous ribonucleases and endogenous RNase. Cordycepin does not have a direct effect on biosynthesis of nuclear poly(A)-binding proteins within the duration of the experiment (8 hrs). The phenomena described are discussed.

Intraperitoneal injection of different amounts of Epygid (2-ethyl-6-methyl-3-oxypyridine) to 3- and 18-month-old rats led to significant reduction of translating activity in vitro of membrane-bound polysomes of brain cells, but not of free polysomes, more so for bound polysomes from 18-month-old animals than those from 3 months old. Separation of polysomes from membranes by Triton X-100 resulted in restoration of template activity to the level of free polysomes. The phenomenon may be related to incorporation of Epygid into the membranes of endoplasmic reticulum which contain a part of cell polysomes on their surface.