Centro de Ciências Biológicas, Departamento de Genética, Universidade Federal de Pernambuco, Recife, PE Brazil.
Genet Mol Biol. 2009 Apr;32(2):276-80. doi: 10.1590/S1415-47572009005000040. Epub 2009 May 10.
Meiotic and mitotic chromosomes of Dichotomius nisus, D. semisquamosus and D. sericeus were analyzed after conventional staining, C-banding and silver nitrate staining. In addition, Dichotomius nisus and D. semisquamosus chromosomes were also analyzed after fluorescent in situ hybridization (FISH) with an rDNA probe. The species analyzed had an asymmetrical karyotype with 2n = 18 and meta-submetacentric chromosomes. The sex determination mechanism was of the Xy(p) type in D. nisus and D. semisquamosus and of the Xy (r) type in D. sericeus. C-banding revealed the presence of pericentromeric blocks of constitutive heterochromatin (CH) in all the chromosomes of the three species. After silver staining, the nucleolar organizer regions (NORs) were located in autosomes of D. semisquamosus and D. sericeus and in the sexual bivalent of D. nisus. FISH with an rDNA probe confirmed NORs location in D. semisquamosus and in D. nisus. Our results suggest that chromosome inversions and fusions occurred during the evolution of the group.
采用常规染色、C-带和银染技术分析了双栉异角蜉蝣、半栉异角蜉蝣和丝栉异角蜉蝣的减数分裂和有丝分裂染色体。此外，还通过荧光原位杂交（FISH）用 rDNA 探针分析了双栉异角蜉蝣和半栉异角蜉蝣的染色体。分析的物种具有不对称的核型，2n = 18，具有亚中部着丝粒染色体。Xy(p)型决定雌雄性别机制存在于双栉异角蜉蝣和半栉异角蜉蝣中，而 Xy (r) 型决定雌雄性别机制存在于丝栉异角蜉蝣中。C-带显示所有三个物种的所有染色体都具有着丝粒周围的组成型异染色质（CH）块。经过银染后，核仁组织区（NORs）位于半栉异角蜉蝣和丝栉异角蜉蝣的常染色体和双栉异角蜉蝣的性二价体中。rDNA 探针的 FISH 证实了 NORs 在半栉异角蜉蝣和双栉异角蜉蝣中的位置。我们的结果表明，染色体倒位和融合在该组的进化过程中发生了。
