【摘要】 蓖麻蚕核糖体ＲＮＡ基因（ｒＤＮＡ）５′－非转录间隔区有长约１ｋｂ的核骨架结合区ＳＡＲ（ｓｃａｆｏｌｄ－ａｓｓｏｃｉａｔ－ｅｄｒｅｇｉｏｎ）［１］。本文对该ＳＡＲ元件的酵母自主复制功能进一步研究，证明该ＳＡＲ５′端６８８ｂｐ含有１２个ＡＣＳ（ＡＲＳ的核心序列）同源序列，但无ＡＲＳ活性，而其３′端仅３个ＡＣＳ同源序列，但对酵母的转化率比全片段还高４０～５０倍。体外结合实验证明，蓖麻蚕ｒＲＮＡ基因的ＳＡＲ能专一地同酵母核骨架结合，提示ＡＲＳ的功能体现与核骨架结合紧密相关。ｒＲＮＡ基因ＳＡＲ与ＡＲＳ的功能在进化上可能是很保守的。在此基础上可进一步分析ＳＡＲ中与ＤＮＡ复制相关的正调及负调元件。更多还原

【Abstract】 The one kilobase scaffoldassociated region (SAR)of silkworm Attacus ricini rRNA gene (rDNA) has been identified previously. To investigate the critical sequence and the relative activity of ARS (autonomously replicating sequence), a set of restriction from covered the whole rRNA gene unit were subcloned into the nonreplicative pSKY vector. Among the seven plasmids constructed, the plasmid pSEY, having SAR, gave obvious positive replication activity in yeast as determined by the transformation efficiency. Further dissection of SAR demonstrated that plasmid pAAY, having a 0.26 kb small fragment of SAR was 40-50 fold more active then the whole SAR, while pSAY, having the remaining part of SAR, showed no activity. There were fifteen ARS consensus sequence (ACS) within SAR being identified through sequence alignment. It was found that only three ACSs in pAAY, located at the 3′end of SAR displayed a positive ARS activity and the remaining sequence having the other twelve ACSs functioned as a repressor. The in vitro binding assay showed that SAR from the silkworm rRNA gene bound to the yeast nuclear scaffold. These results suggest that SAR is evolutionarily conserved, and there is a close correlation between SAR and ARS activity. Detailed analysis of the positive and negative regulatory elements in SAR can be carried out based on these results.更多还原