5-溴脱氧尿嘧啶核苷对鸡胚神经视纲膜染色质、DNA的园二色性光谱与热变性的影响

使用5-溴脱氧尿嘧啶核苷(Brdu),对鸡胚神经视纲膜的形态发生与生化分化进行研究,以探讨基因的调节作用。 发育六天的鸡胚视纲膜经Brdu短期培养后,形态发生不可逆地抑制。但Brdu对发育七天的视纲膜的抑制作用是可逆的,发育九天的鸡胚视纲膜却不受其影响。 从发育六、七、九天的鸡胚视纲膜中提取DNA,进行CD谱的研究,与对照相比,经Brdu处理的视纲膜DNA的CD谱发生兰移,而且在260—280nm及290—300nm区域的吸收强度发生改变。Brdu还使发育六、七天的视纲膜染色质的CD谱发生明显变化,但发育九天的视纲膜染色质的CD谱的变化则不明显。对经Brdu作用的视纲膜DNA和染色质进行热稳定性分析结果也说明发育六、七、九天的视纲膜DNA的值和增色效应都有所增加,而染色质热稳定性的变化却不完全一致。

CIRCULAR DICHROISM AND THERMAL DENATURATION STUDIES OF CHROMATIN AND DNA EROM BRDUTREATED EMBRYONIC CHICKEN NEURAL RETINA

o-B r o m o - 2' - deoxyuridiue (Brdu), an analogue of thymidine, is used to prob gene regulation during the histogenesis and biochemical differentation in chick embryonic neural retina.After short treatment with Brdu, the histogenesis of 6-day retina was inhibited irreversibly. These effects of inhibition were. however, reversible in 7-day retina and absent in 9 - day retina.The study of CD spectra of DNA from 6, 7 and 9 - day retina showed that Brdu treatment caused a blue shift and an increased positive ellipticity in the 260-280 nm region and an increased negative ellipticity in 290-300 nm region in CD spectra. When the same observation wa; made in the chromatir. these changes in CD spectra were obvious in 6 and 7 day retina, but barely detectable in 9 - day retina. Analysis of thermal stability of Brdu- treated DNA also revealed that Brdu treatment causes an increase in melting temperature and hyperchromic effect in DNA from 6, 7 and 9 - day retina. Again, these effects were apparent only for 6 and 7-day retina.