Hausner Georg, Wang Xi
Department of Microbiology, University of Mannitoba, Winnipeg, Canada.
Genome. 2005 Aug;48(4):648-60. doi: 10.1139/g05-037.
The internal transcribed spacers of the ribosomal DNA tandem repeat were examined in members of the ascomycetous genus Sphaeronaemella. Species of Sphaeronaemella and its mitotic counterpart Gabarnaudia, have a compact rDNA gene arrangement due to unusually short internal transcribed spacer (ITS) regions. Examination of these regions from phylogenetically related taxa, Cornuvesica, Gondwanamyces, and Ceratocystis, showed that their ITS1 and ITS2 regions could be folded into central hairpin-like structures with the size reduction in species of Sphaeronaemella being due to length reduction of the main-hairpin and the loss of smaller hairpin-like structures that emanate from the main hairpin. A databank compilation, combined with newly obtained sequences, provided an ITS data set that includes sequences of 600 species belonging to the Ascomycota. Correlation analysis revealed that the sizes of ITS1 and ITS2 show a strong positive correlation, suggesting that the 2 rDNA regions have co-evolved. This supports biochemical evidence indicating that the ITS1 and ITS2 segments interact to facilitate the maturation of the rRNA precursor.
对子囊菌纲球腔菌属的成员进行了核糖体DNA串联重复序列的内部转录间隔区研究。球腔菌属及其有丝分裂对应属加巴纳腔菌属的物种，由于内部转录间隔区（ITS）区域异常短，具有紧凑的核糖体DNA基因排列。对来自系统发育相关类群（玉米腔菌属、冈瓦纳腔菌属和长喙壳属）的这些区域进行研究表明，它们的ITS1和ITS2区域可以折叠成中央发夹样结构，球腔菌属物种的尺寸减小是由于主发夹长度缩短以及从主发夹发出的较小发夹样结构的丢失。一个数据库汇编，结合新获得的序列，提供了一个ITS数据集，其中包括属于子囊菌门的600个物种的序列。相关性分析表明，ITS1和ITS2的大小呈现出很强的正相关性，这表明这两个核糖体DNA区域是共同进化的。这支持了生化证据，表明ITS1和ITS2片段相互作用以促进核糖体RNA前体的成熟。
