The effect of triiodothyronine (L-T₃) on the protein, RNA and DNA fractions of the thymus nuclei of growth-arrested sulfaguanidine-fed rats has been studied.
A single dose of 15 µg of L-T₃ stimulated the incorporation of ¹⁴C-labelled amino acids into total nuclear protein, whole histone and histone fractions. The incorporation of the labelled amino acid into nuclear protein was increased 40 percent over the control 4 hours after the administration of L-T₃. The incorporation of alanine-1-¹⁴C into the total histone fraction reached a maximum 4 hours after the administration of L-T₃ and then decreased 8 and 16 hours after the administration of L-T₃. The incorporation of alanine-1-¹⁴C into histone fraction f₁ reached a maximum at 4 hours after the administration of L-T₃ while the incorporation into fractions f<sub>2a</sub>, f<sub>2b</sub> and f₃ did not reach a maximum until 8 hours after the administration of L-T₃.
Time course studies showed that the protein and RNA moieties of thymus chromatin of rats injected with a single dose of L-T₃ was increased to a maximum at 4 hours. The T<sub>m</sub> of chromatin was increased 2° by L-T₃ administration as early as 2 hours. However, the T<sub>m</sub> of DNA was not affected.
Four hours after the administration of L-T₃ the template efficiency increased 171 percent. The template efficiency of DNA was not affected by L-T₃.
These results demonstrate that thyroid hormones modify the chromatin in such a way that the template efficiency is increased. An hypothesis for the mechanism of thyroid hormone action was presented. / Ph. D.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/37198 |
| Date | 13 January 2010 |
| Creators | Ruark, Edwin Warren |
| Contributors | Biochemistry and Nutrition |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Dissertation, Text |
| Format | 89 leaves, BTD, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | OCLC# 22366655, LD5655.V856_1970.R8.pdf |
Page generated in 0.0024 seconds