Post - transcriptional regulation of messenger abundance in rat Bver and hepatorru

Saturation hybridisation with labelled single—copy UTA shows that polysomal poly(A)+ HHA of rat liver and of a minimus—deviation rat hepatcma cell—line (HTC) have similar total complexities and that few sequenoes are specific to either coil-type. Hybridisation kinetios of polygonal olKls with tenplate and heterologous oell RHAB indioate that • proportion of liver messengers are at greatly reduced abundance in the hepatoma, but not the converse. Hybridisations using fractionated CIHAB enriched for abundant polysanal sequences confirm these findingsi on average, abundant liver mHHAs are about 100-fold rarer in hepatoma, whereas abundant hepatoma mBSAs are only 3-fold rarer in l iver. Ibis pattern i s also implied by oell-free translation of polysomal poly(A)+ RHAB. The reactions of total and fractionated polysanal oIHA probes with poly(l)+ nuclear RHA indicate that there i s much less disparity in abundance of these sequences at nuclear level , Implying that the differences arise, at least in part, poet— transoriptionally* He interpret the altered mRHA abundances in the hepatoma in terms both of i t s decreased functional specialisation and i t s abil ity to proliferate.