Adilardi Renzo Sebastián, Ojanguren-Affilastro Andrés Alejandro, Mattoni Camilo Iván, Mola Liliana María
Laboratorio de Citogenética y Evolución, Departamento de Ecología, Genética y Evolución, IEGEBA (CONICET-UBA), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160, C1428EGA, CABA, Argentina,
Genetica. 2015 Aug;143(4):393-401. doi: 10.1007/s10709-015-9838-1. Epub 2015 Apr 22.
All cytogenetically studied scorpions present male achiasmatic meiosis and lack heteromorphic sex chromosomes. In contrast, information about female meiosis in scorpions is scarce due to the difficulty of finding meiotic cells. The genus Zabius includes three described species and no chromosome studies have been performed on it until now. We analyzed the constitutive heterochromatin distribution, NORs and telomeric sequences in mitosis and meiosis of males and females of different populations of Zabius fuscus. All specimens presented 2n = 18 holokinetic chromosomes that gradually decreased in size. Male meiosis presented nine bivalents and a polymorphism for one reciprocal translocation in one population. Telomeric signals were detected at every terminal region, confirming also the presence of a (TTAGG) n motif in Buthidae. Constitutive heterochromatin was found in three chromosome pairs at a terminal region; moreover, NORs were embedded in the heterochromatic region of the largest pair. Chromosome size and landmarks allowed us to propose the chromosomes involved in the rearrangement. In four females, cells at different prophase I stages were analyzed. We describe a diffuse stage and the presence of ring-shaped bivalents. We discuss the possible origin of these bivalents in the framework of chiasmatic or achiasmatic female meiosis. These results contribute to increase the scarce evidence of female meiosis in scorpions and raise new questions about its mechanism.
所有经过细胞遗传学研究的蝎子都呈现出雄性无交叉减数分裂，并且缺乏异形性染色体。相比之下，由于难以找到减数分裂细胞，关于蝎子雌性减数分裂的信息很少。扎比乌斯属包括三个已描述的物种，到目前为止尚未对其进行过染色体研究。我们分析了不同种群的深色扎比乌斯雄性和雌性有丝分裂和减数分裂中的组成型异染色质分布、核仁组织区（NORs）和端粒序列。所有标本都有2n = 18条全动染色体，其大小逐渐减小。雄性减数分裂呈现出九个二价体，并且在一个种群中存在一种相互易位的多态性。在每个末端区域都检测到了端粒信号，这也证实了钳蝎科中存在（TTAGG）n基序。在三个染色体对的末端区域发现了组成型异染色质；此外，核仁组织区位于最大一对染色体的异染色质区域内。染色体大小和特征使我们能够推测参与重排的染色体。对四只雌性的不同减数第一次分裂前期阶段的细胞进行了分析。我们描述了一个弥散期以及环形二价体的存在。我们在交叉或无交叉雌性减数分裂的框架内讨论了这些二价体的可能起源。这些结果有助于增加关于蝎子雌性减数分裂的稀缺证据，并对其机制提出了新的问题。
