A cytogenetic analysis based on the integration of a number of different chromosomal methodologies, including chromosome microdissection was carried out to characterize the chromosomally polymorphic Hypostomusregani population from the Paraguay River basin, state of Mato Grosso do Sul in Brazil. All specimens had 2n=72 (FN=116) but two distinct karyotype formulas: karyomorph A (12m+14sm+18s+28a) and karyomorph B (13m+14sm+17st+28a). Karyomorph A and B differed only for pair 19 that consisted of two subtelocentrics in karyomorph A and a large metacentric and a subtelocentric in karyomorph B. This heteromorphism was due to extensive heterochromatinization of the short arm of the large metacentric, as highlighted by C-banding. The microdissection of the large metacentric of pair 19 allowed the production of a probe, named HrV (Hypostomusregani Variant), that hybridized to the whole p arm of the large metacentric and the pericentromeric region of the short arm of its (subtelocentric) homologue (karyomorph B) and of both homologs of pair 19 in karyomorph A. Additional cytogenetic techniques (FISH with 18S and 5S rDNA probes, CMA3 and DAPI staining) allowed a finer distinction of the two karyomorphs. These results reinforced the hypothesis that the novel large metacentric of H.regani (karyomorph B) was the result of the amplification of heterochromatin segments, which contributed to karyotypic diversification in this species.

中文翻译：

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来自巴拉圭河流域（巴西马托格罗索州）的新热带装甲cat鱼Hypostomusregani（Ihering，1905年）（Loricariidae，Hypostominae）的本构异染色质异质性。

进行了细胞遗传学分析，基于多种不同染色体方法学的整合，包括染色体显微切割，以表征巴西南马托格罗索州巴拉圭河流域的多态性Hypostomusregani染色体。所有标本具有2n = 72（FN = 116），但有两个不同的核型公式：核型A（12m + 14sm + 18s + 28a）和核型B（13m + 14sm + 17st + 28a）。核型A和B仅在19对中有所不同，对19由核型A中的两个亚远心中心和核型B中的一个大亚中心和一个亚远心组成。这种异质性是由于大亚中心的短臂发生了广泛的异染色质作用，如C带所示。对19的大偏心点的显微解剖可以产生探针，称为HrV（Hypostomusregani Variant），可与其（亚心型）同源物（核型B）的大中中心和短臂的近端着丝粒区域的整个p臂杂交，并与核型A中19对的两个同系物杂交。其他细胞遗传学技术（用18S和5S rDNA探针进行FISH，CMA3和DAPI染色）可以更好地区分这两个核型。这些结果加强了这样的假说，即新的大隐球菌H.regani（核型B）是异染色质片段扩增的结果，这有助于该物种的核型多样化。其他细胞遗传学技术（带有18S和5S rDNA探针的FISH，CMA3和DAPI染色）可以对两种核型进行更好的区分。这些结果加强了这样的假说，即新的大隐球菌H.regani（核型B）是异染色质片段扩增的结果，这有助于该物种的核型多样化。其他细胞遗传学技术（带有18S和5S rDNA探针的FISH，CMA3和DAPI染色）可以对两种核型进行更好的区分。这些结果加强了这样的假说，即新的大隐球菌H.regani（核型B）是异染色质片段扩增的结果，这有助于该物种的核型多样化。