Sobol' M A, Kordium E L, Gonzalez-Camacho F, Rodriguez-Vilarino V, Medina F J
Tsitol Genet. 2005 Jan-Feb;39(1):52-62.
Fibrillarin and plant nucleolin homologue NopA64 are two important nucleolar proteins involved in pre-rRNA processing. To understand better the effects of the altered gravity environment on the nucleolus functioning we have investigated the location of fibrillarin and NopA64 in nucleolar subcomponents of cress (Lepidium sativum L.) root meristematic cells grown under simulated microgravity that was compared to the control cells grown in normal conditions at I g. Cress fibrillarin was first shown to have the molecular weight 41 kDa. Both fibrillarin and NopA64 in the cress cell nucleolus are located in the zones known to contain processing pre-rRNA molecules as it has been previously reported in other species. The data confirm participation of these proteins in processomes--RNP complex particles involved in pre-rRNA processing. Under altered gravity a decrease in the quantity of both fibrillarin and NopA64 in the transition zone between fibrillar centres and the dense fibrillar component was observed, compared to control, which could point out to a lowering of the level of early pre-rRNA processing in these experimental conditions. This decrease was also detected in the bulk of the dense fibrillar component. These data support the idea that altered (reduced) gravity results in lowering the level of functional activity of the nucleolus.
纤维原纤维蛋白和植物核仁素同源物NopA64是参与前体核糖体RNA（pre-rRNA）加工的两种重要核仁蛋白。为了更好地理解重力环境改变对核仁功能的影响，我们研究了纤维原纤维蛋白和NopA64在水芹（独行菜）根分生组织细胞的核仁亚组分中的定位，这些细胞在模拟微重力条件下生长，并与在1g正常条件下生长的对照细胞进行比较。水芹纤维原纤维蛋白首次被证明分子量为41 kDa。水芹细胞核仁中的纤维原纤维蛋白和NopA64都位于已知含有加工前体rRNA分子的区域，正如之前在其他物种中所报道的那样。这些数据证实了这些蛋白质参与了加工体——参与前体rRNA加工的核糖核蛋白复合体颗粒。与对照相比，在重力改变的情况下，观察到纤维状中心和致密纤维组分之间的过渡区中纤维原纤维蛋白和NopA64的数量均减少，这可能表明在这些实验条件下早期前体rRNA加工水平降低。在致密纤维组分的大部分区域也检测到了这种减少。这些数据支持了重力改变（降低）导致核仁功能活性水平降低的观点。
