Department of Cell and Molecular Biology, Faculty of Sciences, University of A Coruña, Spain.
Biochem Genet. 2009 Dec;47(11-12):775-88. doi: 10.1007/s10528-009-9276-9.
For a study of 5S ribosomal genes (rDNA) in the razor clam Ensis macha, the 5S rDNA region was amplified and sequenced. Two variants, so-called type I or short repeat (approximately 430 bp) and type II or long repeat (approximately 735 bp), appeared to be the main components of the 5S rDNA of this species. Their spacers differed markedly, both in length and nucleotide composition. The organization of the two variants was investigated by amplifying the genomic DNA with primers based on the sequence of the type I and type II spacers. PCR amplification products with primers EMLbF and EMSbR showed that the long and short repeats are associated within the same tandem array, suggesting an intermixed arrangement of both spacers. Nevertheless, amplifications carried out with inverse primers EMSinvF/R and EMLinvF/R revealed that some short and long repeats are contiguous in the same tandem array. This is the first report of the coexistence of two variable spacers in the same tandem array in bivalve mollusks.
为了研究刀额新对虾（Ensis macha）的 5S 核糖体基因（rDNA），我们扩增并测序了 5S rDNA 区域。两种变体，即所谓的 I 型或短重复（约 430bp）和 II 型或长重复（约 735bp），似乎是该物种 5S rDNA 的主要成分。它们的间隔区在长度和核苷酸组成上都有明显的差异。通过使用基于 I 型和 II 型间隔区序列的引物扩增基因组 DNA，研究了两种变体的组织。使用引物 EMLbF 和 EMSbR 进行的 PCR 扩增产物表明，长重复和短重复在同一串联排列中相关，表明两个间隔区的混合排列。然而，使用反向引物 EMSinvF/R 和 EMLinvF/R 进行的扩增表明，一些短重复和长重复在同一串联排列中是连续的。这是首例报道双壳类软体动物中同一串联排列中存在两种可变间隔区的情况。
