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

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.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Programa de Pesquisas em Biodiversidade do Semiarido - PPBio SemiaridoUniv Estadual Paulista, UNESP, Dept Biol, Inst Biociencias, BR-13506900 São Paulo, BrazilUniv Fed Piaui, UFPI, BR-64800000 Floriano, Piaui, BrazilUniv Fed Minas Gerais, Inst Ciencias Biol, Programa Posgrad Zool, Belo Horizonte, MG, BrazilUniversidade Federal de São Paulo, Dept Ciencias Biol, UNIFESP, BR-09972270 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Ciencias Biol, UNIFESP, BR-09972270 São Paulo, BrazilFAPESP: 2010/14226-2FAPESP: 2011/21643-1CNPq: 478630/2010-7Programa de Pesquisas em Biodiversidade do Semiarido - PPBio Semiarido: CNPq 558317/2009-0Programa de Pesquisas em Biodiversidade do Semiarido - PPBio Semiarido: 457471/2012-3Web of Scienc