Dupuy-Coin A M, Pebusque M J, Seite R, Bouteille M
J Submicrosc Cytol. 1986 Jan;18(1):21-7.
A quantitative electron microscopy autoradiography method was used to locate the sites of initial rRNA transcription and to determine whether there was a variability of fibrillar centres size related to nucleolar transcription in nucleoli of sympathetic neurons of a rat killed during the dark span of its light-dark cycle. Indeed, in this model two types of fibrillar centres (nucleolar organizing regions) were observed: a single large type characteristic of this phase of the photoperiod and a small type composed by several small fibrillar centres of normal size. The present results clearly demonstrated that: there was no incorporation into the fibrillar centres themselves; the rRNA transcription sites were restricted to the ribonucleoprotein (RNP) fibrillar component and the products thereafter migrated into the RNP granular component. There was no variability of fibrillar centres size related to nucleolar transcription. The level of transcription was found to be identical around the two types of fibrillar centres. They might be considered as equivalent. The results provide evidence that at least in this model, the size of fibrillar centres and the transcriptional activity are not correlated. Other factors must therefore be responsible for the difference in size.
采用定量电子显微镜放射自显影方法来定位初始rRNA转录位点，并确定在明暗周期的暗期处死的大鼠交感神经元核仁中，纤维中心大小与核仁转录是否存在变异性。实际上，在该模型中观察到两种类型的纤维中心（核仁组织区）：一种是光周期此阶段特有的单个大型纤维中心，另一种是由几个正常大小的小纤维中心组成的小型纤维中心。目前的结果清楚地表明：纤维中心本身没有掺入；rRNA转录位点局限于核糖核蛋白（RNP）纤维成分，其产物随后迁移到RNP颗粒成分中。纤维中心大小与核仁转录不存在变异性。发现两种类型的纤维中心周围的转录水平相同。它们可被视为等效的。结果提供了证据，表明至少在该模型中，纤维中心的大小与转录活性不相关。因此，其他因素必定是造成大小差异的原因。
