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Интеллектуальная Система Тематического Исследования НАукометрических данных |
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Study of the effect of UV light on the thermal melting of rat liver nuclei in the presence of multiply charged cations via differential scanning calorimetryтезисы доклада Тезисы
- Авторы: Prusov A., Kolomijtseva G., Smirnova T.
- Сборник: Book of abstracts "INTERNATIONAL CONFERENCE ON RADIATION APPLICATIONS" (RAP 2021)
- Тезисы
- Год издания: 2021
- Место издания: Sievert Association Niš, Serbia
- Первая страница: 81
- Аннотация: The non-invasive method of differential scanning calorimetry (DSC) has been used to study the action of UV-light on the thermal stability nuclei from rat liver. Nuclei with condensed chromatin were prepared according to the standart methods in presence of polyamines (20 mM triethanolamine-HCl (TEA), 0,5 mM spermidine and 0,2 mM spermine, 2 mM EDTA, 80 mM NaCl) (N-PA) and in a low ionic strength buffer (20 mM TEA) with 5 mM MgCl2 (N-Mg). EM-pictures of both types of nuclei were similar. The melting profiles of chromatin in isolated nuclei at the scanning rate of 2ºC/min in the temperature range 25-110°C were different. In case of N-PA we observed 3 clear structural transitions (Tm) near 75°C (peak 1), 89°C (peak 2) and 102ºC (peak 3) with the ratio of the areas under the peaks 15:48:37. They were identified as the melting of nucleosome core histones, of relaxed and topologically strained DNA, respectively. However in the presence of 5 mM MgCl2 there was a integration of the 1 and 2 peaks to a single basic endoterm at Tm near 83ºC. We observed also a small peak as the shoulder of the main peak at 89 ºC. Values of total ∆H for N-PA and N-Mg were 26 and 32 kJ/mol nucleotides, respectively. UV-irradiation of the nuclei at λ =254 nm and at a dose 1,8 J/m2 induced changes in the melting profiles. The most striking observation concerned the peaks 2 and 3 of the N-PA which melted 2-2,5°C below the Tm of control peaks. The relation of peaks 1, 2 and 3 has become 12:60:28 due to a significant decrease peaks 1 (histones melting) and 3 (melting of topologically strained DNA) and the total ∆H decreased by almost half. Peak 2 material with Tm 89º (relaxed DNA) turned out to be the less sensitive to UV-irradiation. In the case of N-Mg the Tm of peaks diminished only by 1,5°C, enthalpy of transition peak 3 decreased by 2 times but total ∆H only slightly reduced to 29,5 kJ/mole nucleotides. We interpret our DSC results as a consequence of UV-induced local distortions in chromatin, reducing the molecular weight of DNA and the proportion of its topologically strained fraction and destabilizing the nucleosome histones octamer. The nuclei isolated in magnesium are less sensitive to UV light than in polyamines. However UV-induced DNA lesions formed throughout nuclear chromatin probably do not cause alternations in its morphology.
- Добавил в систему: Прусов Андрей Николаевич