Serfling E
Chromosoma. 1976 Sep 10;57(3):271-83. doi: 10.1007/BF00295212.
Experimental results on the transcription of Balbiani rings BR 1 and BR 2 of Chironomus thummi salivary gland chromosomes are presented. The DNA of Balbiani ring 2, which is the most active puff in larvae, is transcribed into large RNA molecules of about 22 X 10(6) D which resist degradation by heating, formamide or urea treatment. The asymmetrical distribution of electrophoretic profiles of BR 2 RNA and the appearence of a symmetrical BR RNA peak in the nucleoplasm suggest the synthesis of (mainly) one RNA fraction in BR 2. The gel electrophoretic patterns of BR 1 RNA are, on the other hand, characterized by the appearance of two main fractions of high molecular weight RNA, one of which corresponds in molecular weight (about 22 X 10(6) D) to BR 2 RNA. The second RNA fraction is significantly smaller in molecular size (molecular weight: about 10 X 10(6) D) and, like the 22 X 10(6) D RNA fractions of the two Balbiani rings, resistant against heating in 8 M urea. Binding to poly (U) sepharose of a significant part of Balbiani ring RNA suggests the existence of poly (A) and/or oligo (A) sequences in the Balbiani ring RNA. -- In situ hybridization of BR RNA to the salivary gland chromosomes reveals accumulation of silver grains over the Balbiani ring regions only and demonstrates the restriction of BR DNA sequences to the corresponding Balbiani ring.
本文展示了有关摇蚊唾液腺染色体上巴尔比亚尼环BR 1和BR 2转录的实验结果。巴尔比亚尼环2的DNA是幼虫中最活跃的胀泡，它被转录成约22×10⁶D的大RNA分子，这些分子能抵抗加热、甲酰胺或尿素处理导致的降解。BR 2 RNA电泳图谱的不对称分布以及核质中对称的BR RNA峰的出现表明（主要）在BR 2中合成了一种RNA组分。另一方面，BR 1 RNA的凝胶电泳图谱的特征是出现了两个高分子量RNA的主要组分，其中一个在分子量（约22×10⁶D）上与BR 2 RNA相对应。第二个RNA组分的分子大小明显较小（分子量：约10×10⁶D），并且与两个巴尔比亚尼环的22×10⁶D RNA组分一样，在8M尿素中加热时具有抗性。巴尔比亚尼环RNA的很大一部分与聚（U）琼脂糖结合，这表明巴尔比亚尼环RNA中存在聚（A）和/或寡聚（A）序列。——BR RNA与唾液腺染色体的原位杂交显示银颗粒仅在巴尔比亚尼环区域积累，并证明BR DNA序列局限于相应的巴尔比亚尼环。
