Location of 45S Ribosomal Genes in Mitotic and Meiotic Chromosomes of Buthid Scorpions

• Autor(a) principal: Mattos, Viviane Fagundes
• Data de Publicação: 2014
• Outros Autores: Carvalho, Leonardo Sousa, Cella, Doralice Maria, Schneider, Marielle Cristina [UNIFESP]
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNIFESP
• Texto Completo: http://dx.doi.org/10.2108/zs140005; http://repositorio.unifesp.br/handle/11600/38133
• topic: constitutive heterochromatin; chromosome chain; diploid number; fluorescent in situ hybridization; holocentric chromosomes; rDNA

Buthid scorpions exhibit a high variability in diploid number within genera and even within species. Cytogenetically, Buthidae differs from other families of Scorpiones based on its low diploid numbers, holocentric chromosomes, and complex chromosomal chains, which form during meiosis. in this study, we analyzed the distribution of the 45S ribosomal DNA (rDNA) genes in the mitotic and meiotic chromosomes of seven buthid species belonging to the genera Rhopalurus and Tityus with the ultimate goal of elucidating the chromosome organization in these scorpions. the chromosome number ranged from 2n = 6 to 2n = 28. Despite the high variance in diploid number, all species examined carried their 45S rDNA sites in the terminal region of exactly two chromosomes. Analyses of meiotic cells revealed 45S rDNA clusters in the chromosomal chains of Rhopalurus agamemnon, Tityus bahiensis, Tityus confluens, and Tityus martinpaechi, or in bivalent-like configuration in Rhopalurus rochai, Tityus bahiensis, Tityus confluens, Tityus fasciolatus, and Tityus paraguayensis. in the species examined, the 45S rDNA sites colocalized with constitutive heterochromatin regions. in light of the high chromosome variability and maintenance of number and terminal position of 45S rDNA sites in buthids, the heterochromatin may act to conserve the integrity of the ribosomal genes.