Effect of Estrogen and Progesterone on the Characteristics of Newly Synthesized RNA in Uterine Tissue

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In this study, ovarial steroid hormone was administered in ovariectomized or immature animals to observe the onset of RNA synthesis by uterine tissue in response to this hormone as well as the characteristics of newly synthesized RNA.
After extracting RNA from the uterine tissue of rats and rabbits, the sample was analyzed with sucrose density gradient.
While using DNA of rabbit liver as the template, the inhibition on hybrid formation of ³H-labelled estrogen dependent RNA or progesterone dependent RNA by addition of a large dose of unlabelled RNA was studied in the same tissue and in different tissue. This was also studied between RNA in the uterus treated with estrogen alone and that in the uterus of animals treated with estrogen and progesterone. As a result, a constant competition curve was obtained along with the increase of unlabelled RNA among RNA of the same kinds.
The competition between labelled E-RNA-unlabelled E.P.-RNA was not much different from that in the experimental system between labelled E-RNA-unlabelled ERNA in the system of labelled E.P.-RNA-unlabelled E-RNA. In the system of labelled E.P.-RNA-unlabelled E-RNA, the competion was decreased by about 10% in comparison with the combination with unlabelled E.P.-RNA.
Hybrid formation of labelled E-RNA against rabbit liver DNA was not subjected to competition by unlabelled E. coli-RNA, liver-RNA and human placenta-RNA, but a marked competion by unlabelled rabbit placenta-RNA was noted.
According to these results, administration of progesterone following estrogen pretreatment resulted in the possibility of the opening of a gene locus apart from estrogen in the uterine cells, leading to RNA-transcription.
Cosiderable qualitative common characteristics were noted between placenta and uterus RNA.
E. coli and human placenta RNA show a different base composition or arrangement and form scarcely any hybrid with rabbit DNA.