Molecular cytogenetics and allotetraploidy in the red vizcacha rat, Tympanoctomys barrerae (Rodentia, Octodontidae)
Molecular cytogenetics and allotetraploidy in the red vizcacha rat, Tympanoctomys barrerae (Rodentia, Octodontidae)
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DOI：
10.1016/j.ygeno.2006.02.010
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发表时间：
2006-08-01
期刊：
影响因子：
4.4
通讯作者：
Cebrian, I.
中科院分区：
文献类型：
--
作者：
Gallardo, M. H.;Gonzalez, C. A.;Cebrian, I.
哺乳动物多倍体在理论上是不可能存在的，但在红色vizcacha大鼠Tympanoctomys barrerae （2n = 102）中发现了四倍体，从而推翻了这一理论。作为基因组复制的结果，在该物种的精子和不同的体细胞系中观察到显著增加的细胞尺寸。位点重复先前已被原位PCR和单拷贝基因的Southern blot分析证实。在这里，我们通过荧光原位杂交证实了多拷贝（主要rnas）和单拷贝（Hoxc8）基因的重复位点。我们还证明了核仁显性（异源多倍体的一种大规模表观遗传沉默现象）解释了T barrerae中只有一对Ag-NOR染色体的存在。核仁显性，以及在该物种的二倍体样减数分裂的g带模式和突触复合体中检测到的染色体异型性，一致表明异源四倍体。同种异体四倍体化可以一致地解释barrerae基因沉默、细胞尺寸和核型特征的特性，这些特性仍然无法通过假设二倍体和重复序列分散获得的大基因组大小来解释。(c) 2006爱思唯尔公司版权所有。
The theoretical impossibility of polyploidy in mammals was overturned by the discovery of tetraploidy in the red vizcacha rat, Tympanoctomys barrerae (2n = 102). As a consequence of genome duplication, remarkably increased cell dimensions are observed in the spermatozoa and in different somatic cell lines of this species. Locus duplication had been previously demonstrated by in situ PCR and Southern blot analysis of single-copy genes. Here, we corroborate duplication of loci in multiple-copy (major rDNAs) and single-copy (Hoxc8) genes by fluorescence in situ hybridization. We also demonstrate that nucleolar dominance, a large-scale epigenetic silencing phenomenon characteristic of allopolyploids, explains the presence of only one Ag-NOR chromosome pair in T barrerae. Nucleolar dominance, together with the chromosomal heteromorphism detected in the G-banding pattern and synaptonemal complexes of the species' diploid-like meiosis, consistently indicates allotetraploidy. Allotetraploidization can coherently explain the peculiarities of gene silencing, cell dimensions, and karyotypic features of T barrerae that remain unexplained by assuming diploidy and a large genome size attained by the dispersion of repetitive sequences. (c) 2006 Elsevier Inc. All rights reserved.