Mola Liliana M, Vrbová Iva, Tosto Daniela S, Zrzavá Magda, Marec František
Laboratory of Cytogenetics and Evolution, Faculty of Exact and Natural Sciences, University of Buenos Aires, Buenos Aires C1428EGA, Argentina.
Institute of Ecology, Genetics and Evolution of Buenos Aires, National Council of Scientific and Technical Research, Buenos Aires C1428EGA, Argentina.
Insects. 2022 Dec 15;13(12):1159. doi: 10.3390/insects13121159.
Odonata have holokinetic chromosomes. About 95% of species have an XX/X0 sex chromosome system, with heterogametic males. There are species with neo-XX/neo-XY sex chromosomes resulting from an X chromosome/autosome fusion. The genus includes 42 species found in the Americas. We analyzed the distribution of the nucleolar organizer region (NOR) using FISH with rDNA probes in (n = 12 + neo-XY), (n = 7 + neo-XY), and (n = 13 + X0). In and , the NOR is located on a large pair of autosomes, which have a secondary constriction in the latter species. In , the NOR is located on the ancestral part of the neo-X chromosome. Meiotic analysis and FISH results in led to the conclusion that the neo-XY system arose by insertion of the ancestral X chromosome into an autosome. Genomic in situ hybridization, performed for the first time in Odonata, highlighted the entire neo-Y chromosome in meiosis of , suggesting that it consists mainly of repetitive DNA. This feature and the terminal chiasma localization suggest an ancient origin of the neo-XY system. Our study provides new information on the origin and evolution of neo-sex chromosomes in Odonata, including new types of chromosomal rearrangements, NOR transposition, and heterochromatin accumulation.
蜻蜓目具有全动性染色体。约95%的物种具有XX/X0性染色体系统，雄性为异配性别。存在因X染色体/常染色体融合而产生新XX/新XY性染色体的物种。该属包括在美洲发现的42个物种。我们使用rDNA探针通过荧光原位杂交（FISH）分析了（n = 12 + 新XY）、（n = 7 + 新XY）和（n = 13 + X0）中核仁组织区（NOR）的分布。在和中，NOR位于一对大的常染色体上，在后者物种中这些常染色体具有次缢痕。在中，NOR位于新X染色体的祖先部分。中的减数分裂分析和FISH结果得出结论，新XY系统是通过将祖先X染色体插入常染色体而产生的。在蜻蜓目中首次进行的基因组原位杂交突出显示了中减数分裂时整个新Y染色体，表明它主要由重复DNA组成。这一特征和末端交叉定位表明新XY系统起源古老。我们的研究提供了关于蜻蜓目新性染色体起源和进化的新信息，包括新型染色体重排、NOR转位和异染色质积累。
