Cioffi M B, Kejnovsky E, Bertollo L A C
Universidade Federal de São Carlos, Departamento de Genética e Evolução, Brazil.
Cytogenet Genome Res. 2011;132(4):289-96. doi: 10.1159/000322058. Epub 2010 Nov 20.
Distribution of 12 mono-, di- and tri-nucleotide microsatellites on the chromosomes of 2 karyomorphs with 2 distinct sex chromosome systems (a simple XX/XY - karyomorph B and a multiple X(1)X(1)X(2)X(2)/X(1)X(2)Y - karyomorph D) in Hoplias malabaricus, commonly referred to as wolf fish, was studied using their physical mapping with fluorescence in situ hybridization (FISH). The distribution patterns of different microsatellites along the chromosomes varied considerably. Strong hybridization signals were observed at subtelomeric and heterochromatic regions of several autosomes, with a different accumulation on the sex chromosomes. A massive accumulation was found in the heterochromatic region of the X chromosome of karyomorph B, whereas microsatellites were gathered at centromeres of both X chromosomes as well as in corresponding regions of the neo-Y chromosome in karyomorph D. Our findings are likely in agreement with models that predict the accumulation of repetitive DNA sequences in regions with very low recombination. This process is however in contrast with what was observed in multiple systems, where such a reduction might be facilitated by the chromosomal rearrangements that are directly associated with the origin of these systems.
使用荧光原位杂交（FISH）物理图谱技术，研究了分布于马拉巴锯脂鲤（俗称狼鱼）2种核型染色体上的12个单核苷酸、二核苷酸和三核苷酸微卫星，这2种核型具有2种不同的性染色体系统（简单的XX/XY——核型B和多重X(1)X(1)X(2)X(2)/X(1)X(2)Y——核型D）。不同微卫星沿染色体的分布模式差异很大。在几条常染色体的亚端粒和异染色质区域观察到强烈的杂交信号，在性染色体上的积累情况不同。在核型B的X染色体异染色质区域发现大量积累，而在核型D中，微卫星聚集在两条X染色体的着丝粒以及新Y染色体的相应区域。我们的发现可能与预测重复DNA序列在重组率极低区域积累的模型一致。然而，这一过程与在多重系统中观察到的情况相反，在多重系统中，这种减少可能是由与这些系统起源直接相关的染色体重排促成的。
