Osheim Y N, Miller O L, Beyer A L
EMBO J. 1986 Dec 20;5(13):3591-6. doi: 10.1002/j.1460-2075.1986.tb04687.x.
We have examined transcription termination of two closely linked Drosophila melanogaster chorion genes, s36-1 and s38-1, using the electron microscope. Our method is unusual and is independent of in vitro nuclear run-on transcription. By measuring transcription unit lengths in chromatin spreads, we can localize efficient termination sites to a region of approximately 210 bp for s36-1 and approximately 365 bp for s38-1. The center of this region is approximately 105 nucleotides downstream of the poly(A) site for the s36-1 gene, and approximately 400 nucleotides downstream for the s38-1 gene. Thus, these two Drosophila chorion genes terminate more closely to their poly(A) addition sites and in a shorter region than many other polyadenylated genes examined to date.
我们利用电子显微镜研究了两个紧密相连的果蝇绒毛膜基因s36-1和s38-1的转录终止。我们的方法不同寻常，且独立于体外核延伸转录。通过测量染色质铺展中的转录单位长度，我们可以将s36-1基因的有效终止位点定位在大约210 bp的区域，将s38-1基因的有效终止位点定位在大约365 bp的区域。该区域的中心在s36-1基因的多聚腺苷酸化位点下游约105个核苷酸处，在s38-1基因的多聚腺苷酸化位点下游约400个核苷酸处。因此，与迄今为止检测的许多其他多聚腺苷酸化基因相比，这两个果蝇绒毛膜基因在更靠近其多聚腺苷酸添加位点的位置终止，且终止区域更短。
