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Administration of hydrocortisone to adrenalectomised rats elevated levels of both free and membrane-bound polysomes in liver and led to marked shifts in their sedimentation profiles in favour of heavier polysomes. The rate of nascent polypeptide formation was also found to be enhanced in response to the hormone but this effect was mainly confined to the site of free polysomes. These results suggest that besides its well-known potentiating action at the transcription level, the hormone elicits selective stimulatory response at the translation level.

Experiments on hybridization of [32P]HnRNA from hydrocortisone-treated rat liver with rat-liver DNA, in competition with unlabelled liver HnRNA from hormone-deficient and treated rats, revealed marked differences in their nucleotide sequence homologies. It was found that the hormone-induced new species of HnRNAs were transcribed both on middle-repetitive and non-repetitive sequences of DNA. However similar differences in the sequence homologies were not detectable in respect of mRNA derived from livers of hydrocortisone-administered and adrenalectomised rats. The results imply that the new species of HnRNA synthesized following hormone treatment may be confined to the nucleus.