The characterization of karyotypes is an important aspect in understanding the structure and evolution of genomes. Polybia is a genus of social wasps of the family Vespidae. This genus has 58 species, but for only 8 of these chromosome number and morphology have been reported in the literature. The aim of this study was to describe and characterize the Polybia fastidiosuscula Saussure karyotype, presenting the first case of a B chromosome in Vespidae. In addition, we investigated the chromatin composition of this species through C-banding, base-specific fluorochrome staining, and physical mapping of 7 microsatellites and 18S rDNA. Four colonies of P. fastidiosuscula from Minas Gerais and Paraná states, Brazil, were analyzed. The chromosome number identified was 2n = 34, and 2 colonies presented a B chromosome. We characterized the chromatin composition of this species, analyzing the existence of different microsatellite-rich heterochromatic regions which are also enriched with AT or GC base pairs. We suggest an intraspecific origin of the B chromosome based on the homology of the heterochromatic composition with A chromosomes and also verify that the TTAGG and TCAGG sequences are not telomeric, but only microsatellites that occur in the centromeres of most chromosomes, as well as GAG and CGG.
Cytogenet Genome Res

中文翻译：

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鲍氏多毛虫（维氏菌）中B染色体的首次记录和通过微卫星作图法研究染色质的组成

核型的表征是理解基因组结构和进化的重要方面。Polybia是Vespidae家族的一种社会黄蜂。该属有58种，但文献中仅报道了其中8种染色体数目和形态。这项研究的目的是描述和表征多毛虫快活型核型，介绍了大戟科中B染色体的第一例。此外，我们通过C带，碱基特异性荧光染料染色以及7个微卫星和18S rDNA的物理作图来研究该物种的染色质组成。P. fastidiosuscula的四个菌落分析了来自巴西米纳斯吉拉斯州和巴拉那州的数据。鉴定出的染色体数为2n = 34，2个菌落呈B染色体。我们表征了该物种的染色质组成，分析了不同的富含微卫星的异色区域的存在，这些区域也富含AT或GC碱基对。我们基于异色成分与A染色体的同源性，提出了B染色体的种内起源，并且还验证了TTAGG和TCAGG序列不是端粒，而是大多数染色体的着丝粒中存在的微卫星，以及GAG和CGG。
细胞遗传学基因组研究