Forman M, Nguyen P, Hula V, Král J
Laboratory of Arachnid Cytogenetics, Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Prague, Czech Republic.
Cytogenet Genome Res. 2013;141(1):43-9. doi: 10.1159/000351041. Epub 2013 May 22.
In terms of cytogenetics, entelegyne araneomorphs are the best studied clade of spiders. The typical karyotype of entelegyne males consists of acrocentric chromosomes, including 2 non-homologous X chromosomes. The present study is focused on the karyotype, nucleolus organising regions (NORs) and sex chromosome behaviour during meiosis of the entelegyne Wadicosa fidelis (Lycosidae). Preparations stained by Giemsa were used to study karyotype and meiosis. NORs were visualised by silver staining and fluorescence in situ hybridisation with 18S rDNA probe. The male karyotype consists of 28 acrocentric elements, including 2 X chromosomes. In contrast to the majority of other spiders, the male sex chromosomes pair during the major part of meiosis. Following an initial period of parallel pairing, the attachment of male sex chromosomes is restricted to centromeric areas and continues until metaphase II. Our study revealed an enormous number of NORs in the population from Galilee and indicates a considerable variability of NOR numbers in this population. The distal regions of 9 or 10 autosomal pairs contain NORs. The obtained data indicate the rapid spread of NORs in the karyotype of W. fidelis, which was presumably caused by ectopic recombinations and subsequent hybridisations of individuals with different NOR genotypes that produced heterozygotes.
在细胞遗传学方面，新蛛亚目蜘蛛是研究得最为透彻的蜘蛛类群。新蛛亚目雄性蜘蛛的典型核型由近端着丝粒染色体组成，包括两条非同源的X染色体。本研究聚焦于新蛛亚目忠实肥腹蛛（狼蛛科）减数分裂过程中的核型、核仁组织区（NORs）以及性染色体行为。采用吉姆萨染色的制片来研究核型和减数分裂。通过银染以及用18S rDNA探针进行荧光原位杂交来观察NORs。雄性核型由28个近端着丝粒元件组成，包括两条X染色体。与大多数其他蜘蛛不同的是，雄性性染色体在减数分裂的大部分时间里都会配对。在初始的平行配对阶段之后，雄性性染色体的附着仅限于着丝粒区域，并持续到中期II。我们的研究揭示了来自加利利地区种群中存在大量的NORs，并且表明该种群中NORs数量存在相当大的变异性。9对或10对常染色体对的远端区域含有NORs。所获得的数据表明NORs在忠实肥腹蛛的核型中迅速扩散，这可能是由异位重组以及随后不同NOR基因型个体之间的杂交产生杂合子所致。
