Sex-Linked Chromosome Heterozygosity in Males of Tityus confluens (Buthidae): A Clue about the Presence of Sex Chromosomes in Scorpions

• Published in: PloS one Vol. 11; no. 10; p. e0164427
• Main Authors: Adilardi, Renzo Sebastián, Ojanguren-Affilastro, Andrés Alejandro, Mola, Liliana María
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 26.10.2016; Public Library of Science (PLoS)
• Subjects: Analysis; Animals; Biology and Life Sciences; Buthidae; Chromosome number; Chromosome rearrangements; Chromosome Segregation; Chromosomes; Embryo, Nonmammalian - metabolism; Embryos; Female; Females; Genetic aspects; Genomes; Heterozygote; Heterozygotes; Homology; Homozygotes; In Situ Hybridization, Fluorescence; Karyotyping; Male; Males; Meiosis; Mitosis; Orthoptera; Population; Scorpiones; Scorpionidae; Scorpions - genetics; Scorpions - growth & development; Sex; Sex Chromosomes; Sex linkage; Tityus; Tityus confluens; Tityus trivittatus; Y Chromosomes; South America; Brazil; Argentina
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0164427

Scorpions of the genus Tityus show holokinetic chromosomes, achiasmatic male meiosis and an absence of heteromorphic sex chromosomes, like all Buthidae. In this work, we analysed the meiotic behaviour and chromosome rearrangements of a population of the scorpion Tityus confluens, characterising the cytotypes of males, females and embryos with different cytogenetic techniques. This revealed that all the females were structural homozygotes, while all the males were structural heterozygotes for different chromosome rearrangements. Four different cytotypes were described in males, which differed in chromosome number (2n = 5 and 2n = 6) and meiotic multivalent configurations (chains of four, five and six chromosomes). Based on a detailed mitotic and meiotic analysis, we propose a sequence of chromosome rearrangements that could give rise to each cytotype and in which fusions have played a major role. Based on the comparison of males, females and a brood of embryos, we also propose that the presence of multivalents in males and homologous pairs in females could be associated with the presence of cryptic sex chromosomes, with the male being the heterogametic sex. We propose that the ancestral karyotype of this species could have had homomorphic XY/XX (male/female) sex chromosomes and a fusion could have occurred between the Y chromosome and an autosome.