Vittorazzi S E, Lourenço L B, Del-Grande M L, Recco-Pimentel S M
Departamento de Anatomia, Biologia Celular, Fisiologia e Biofísica, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), Campinas, Brasil.
Cytogenet Genome Res. 2011;134(2):101-7. doi: 10.1159/000325540. Epub 2011 Apr 2.
In the present study, we describe for the first time a family of 190-bp satellite DNA related to 5S rDNA in anurans and the existence of 2 forms of 5S rDNA, type I (201 bp) and type II (690 bp). The sequences were obtained from genomic DNA of Physalaemus cuvieri from Palmeiras, State of Bahia, Brazil. Analysis of the nucleotide sequence revealed that the satellite DNA obtained by digestion with EcoRI, called PcP190EcoRI, is 70% similar to the coding region of type I 5S rDNA and 66% similar to the coding region of type II 5S rDNA. Membrane hybridization and PCR amplification of the sequence showed that PcP190EcoRI is tandemly repeated. The satellite DNA as well as type I and type II 5S rDNA were localized in P. cuvieri chromosomes by fluorescent in situ hybridization. The PcP190EcoRI sequence was found in the centromeres of chromosomes 1-5 and in the pericentromeric region of chromosome 3. Type I 5S rDNA was detected in chromosome 3, coincident with the site of PcP190EcoRI. Type II 5S rDNA was located interstitially in the long arm of chromosome 5. None of these sequences co-localized with nucleolar organizer regions. Our data suggests that this satellite DNA originates from the 5S ribosomal multigene family, probably by gene duplication, nucleotide divergence and sequence dispersion in the genome.
在本研究中，我们首次描述了一种与无尾两栖类5S rDNA相关的190bp卫星DNA家族，以及两种形式的5S rDNA，即I型（201bp）和II型（690bp）。这些序列是从巴西巴伊亚州帕尔梅拉斯市的库维耶泡蟾的基因组DNA中获得的。核苷酸序列分析表明，经EcoRI酶切获得的卫星DNA，称为PcP190EcoRI，与I型5S rDNA的编码区相似度为70%，与II型5S rDNA的编码区相似度为66%。该序列的膜杂交和PCR扩增显示PcP190EcoRI是串联重复的。通过荧光原位杂交将卫星DNA以及I型和II型5S rDNA定位在库维耶泡蟾的染色体上。在1-5号染色体的着丝粒以及3号染色体的着丝粒周围区域发现了PcP190EcoRI序列。在3号染色体上检测到I型5S rDNA，与PcP190EcoRI的位点一致。II型5S rDNA位于5号染色体长臂的中间位置。这些序列均未与核仁组织区共定位。我们的数据表明，这种卫星DNA可能起源于5S核糖体多基因家族，可能是通过基因复制、核苷酸分歧和基因组中的序列分散产生的。
