Department of Ecology and Environmental Sciences, Faculty of Agriculture, University of the Ryukyus, Nishihara, Okinawa, 9030213, Japan.
Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Sławkowska 17, 31-016, Krakow, Poland.
Sci Rep. 2019 Nov 14;9(1):16860. doi: 10.1038/s41598-019-53416-7.
The cytogenetic characteristics of the grasshopper Podisma sapporensis (two races 2n = 23♂ X0/XX and 2n = 22♂ neo-XY/neo-XX) were analysed through fluorescence in situ hybridization with rDNA and telomeric DNA probes, C-banding, fluorochrome and silver staining. For the first time, samples from the neighbourhood of a hybrid population (i.e., Mikuni Pass population) were studied. Our results indicated a significant degree of chromosomal differentiation between P. sapporensis races when comparing the number and position of the rDNA sites, as well as the heterochromatin composition and distribution obtained by C-banding and DAPI/CMA staining. Telomeric signals were usually detected at the distal and/or subdistal position of the autosomes; however, some chromosome ends lacked signals, probably due to a low number of telomeric repeats. On the other hand, telomeric DNA sequences were found as interstitial telomeric repeats in some autosomes, which can trigger a variety of genome instability. B chromosomes were found in specimens belonging to both main races from nine out of 22 localities. Four types of X chromosomes in the X0/XX race were identified. It was concluded that the physical mapping of rDNA sequences and heterochromatin are useful as additional markers for understanding the phylogeographic patterns of cytogenetic differentiation in P. sapporensis populations.
通过荧光原位杂交（rDNA 和端粒 DNA 探针）、C 带、荧光染料和银染技术，分析了日本蝗（两个种群 2n=23♂ X0/XX 和 2n=22♂ neo-XY/neo-XX）的细胞遗传学特征。首次对杂种群体（即三日月峠种群）附近的样本进行了研究。我们的结果表明，与 rDNA 位点的数量和位置以及 C 带和 DAPI/CMA 染色获得的异染色质组成和分布相比，日本蝗种群之间存在显著的染色体分化程度。端粒信号通常在染色体的远端和/或亚末端位置检测到；然而，一些染色体末端缺乏信号，可能是由于端粒重复序列数量较少。另一方面，在来自 22 个地点中的 9 个地点的两个主要种群的标本中发现了端粒 DNA 序列作为染色体间端粒重复序列，这可能引发多种基因组不稳定性。在九个地方的九个种群中发现了 B 染色体，这些 B 染色体属于两个主要种群。在 X0/XX 种群中鉴定出四种 X 染色体。研究结论认为，rDNA 序列和异染色质的物理作图可作为附加标记，有助于理解日本蝗种群细胞遗传学分化的系统地理模式。
