Sequencing and characterization of the macronuclear rDNA minichromosome of the protozoan Tetrahymena pyriformis
Sequencing and characterization of the macronuclear rDNA minichromosome of the protozoan Tetrahymena pyriformis
复制标题
原生动物梨形四膜虫大核 rDNA 微型染色体的测序和表征
DOI：
10.1016/j.ijbiomac.2020.01.063
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发表时间：
2020
影响因子：
8.2
通讯作者：
Wang Guangying
中科院分区：
文献类型：
--
作者：
Han Xiaojie;Yan Guanxiong;Ma Yang;Miao Wei;Wang Guangying
四膜虫核糖体DNA（rDNA）是研究真核生物DNA复制和基因转录的理想体系。在这项研究中，我们开发了一种新的方法，从四膜虫细胞中提取rDNA，并使用它来测序和注释完整的19，670 bp的大核rDNA小染色体的梨形四膜虫，一个物种，缺乏生殖系微核，不能进行有性生殖。T.梨形虫和嗜热四膜虫的DNA序列进行了比较。结果表明：（i）在四膜虫有性生殖过程中形成rDNA微型染色体回文结构所必需的短反向重复序列（M repeats）在梨形木霉中高度保守; thermophila，具有两个串联结构域，协调调节rDNA复制，T.（3）两个种的35 S pre-rRNA前体具有80.25%的相似性;（4）两个种转录区的G + C含量均高于非转录区，但梨形木的GC偏态更为稳定。新的分离方法和注释信息的T。pyriformisrDNA微型染色体为研究四膜虫的DNA复制和染色体拷贝数控制提供了有用的资源。
Tetrahymenaribosomal DNA (rDNA) is an ideal system for studying eukaryotic DNA replication and gene transcription. In this study, we developed a new method to isolate rDNA fromTetrahymenacells and used it to sequence and annotate the complete 19,670 bp macronuclear rDNA minichromosome ofTetrahymena pyriformis, a species that lacks the germ-line micronucleus and is unable to undergo sexual reproduction. The key features ofT. pyriformisandTetrahymena thermophilarDNA sequences were then compared. Our results showed (i) the short inverted repeats (M repeats) essential for formation of rDNA minichromosome palindromic structure during sexual reproduction inTetrahymenaare highly conserved inT. pyriformis; (ii) in contrast toT. thermophila, which has two tandem domains that coordinately regulate rDNA replication,T. pyriformishas only a single domain; (iii) the 35S pre-rRNA precursor has 80.25% similarity between the two species; and (iv) the G + C content is higher in the transcribed region than the non-transcribed region in both species, but the GC-skew is more stable inT. pyriformis. The new isolation method and annotated information for theT. pyriformisrDNA minichromosome will provide a useful resource for studying DNA replication and chromosome copy number control inTetrahymena.