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INFLUENCE OF NEONATAL HYPOTHYROIDISM UPON TRANSCRIPTION IN ISOLATED RAT BRAIN AND LIVER NUCLEI
Author(s) -
Krawiec L.,
Montalbano C. A.,
Gömez C. J.
Publication year - 1976
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1976.tb07004.x
Subject(s) - transcription (linguistics) , medicine , endocrinology , endogeny , rna , rna polymerase , biology , incubation , thyroid , ionic strength , cerebrum , biochemistry , chemistry , central nervous system , gene , philosophy , linguistics , aqueous solution
The optimum conditions for measuring the transcriptional activity of endogenous RNA polymerase I and I1 were established in low ionic strength incubation mixtures for liver and cerebrum cell nuclei. Both activities were estimated in the presence of Mg 2+ for RNA polymerase 1 and Mn 2+ for RNA polymerase I1 under conditions in which the nuclear morphology is prcscrvcd. The UMPIGMP incorporation ratio was used to determine the type of RNA synthesized and the results were confirmed employing specific inhibitors of RNA synthesis, such as a‐Amanitin and Actinomycin‐D. Neonatal thyroidectomy in the rat diminished the normal growth of body and liver more than the cerebral growth. The transcriptional capacity in the presence of Mg2+ in cerebral cell nuclei was not changed by the absence of thyroid function during postnatal development. Contrariwise, the activity the presence of Mn 2+ was transicntly diminished between the 10th and 13th day of life. When the assays were performed at high ionic strength there were no differences between normal and hypothyroid animals. In liver, thyroid deficiency affected in an early and permanent way the transcription of an AU‐rich RNA. The endogenous activity measured at high ionic strength and that tested in the presence of Mg2+ were altered from the 20th day onward.