Insights into the origin of the high variability of multivalent-meiotic associations in holocentric chromosomes of Tityus (Archaeotityus) scorpions

Insights into the origin of the high variability of multivalent-meiotic associations in holocentric chromosomes of Tityus (Archaeotityus) scorpions

Author Mattos, Viviane Fagundes Google Scholar
Carvalho Currency, Leonardo Sousa Google Scholar
Carvalho, Marcos Andre Google Scholar
Schneider, Marielle Cristina Autor UNIFESP Google Scholar
Abstract Scorpions represent an intriguing group of animals characterized by a high incidence of heterozygous chromosomal rearrangements. In this work, we examined six species of Tityus (Archaeotityus) from Brazilian fauna with a particular focus on elucidating the rearrangements responsible for the intraspecific variability of diploid number and the presence of long chromosomal chains in meiosis. To access any interpopulation diversity, we also studied individuals from four species representing distinct localities. Most species demonstrated intraspecific polymorphism in diploid number (2n = 19 and 2n = 20 in T. clathratus, T. mattogrossensis, and T. pusillus, 2n = 16, 2n = 17 and 2n = 18 in T. paraguayensis, and 2n = 16 and 2n = 24 in T. silvestris) and multi-chromosomal associations during meiosis I, which differed even among individuals with the same chromosome number. In some species, the heterozygous rearrangements were not fixed, resulting such as in Tityus clathatrus, in 11 different chromosomal configurations recognized within a same population. Based on meiotic chromosome behaviour, we suggested that independent rearrangements (fusion/fission and reciprocal translocations), occurring in different combinations, originated the multi-chromosomal chains. To evaluate the effects of these chromosome chains on meiotic segregation, we applied the chi-square test in metaphase II cells. The non-significant occurrence of aneuploid nuclei indicated that non-disjunction was negligible in specimens bearing heterozygous rearrangements. Finally, based on our analysis of many chromosome characteristics, e.g., holocentricity, achiasmate meiosis, endopolyploidy, ability to segregate heterosynaptic or unsynapsed chromosomes, (TTAGG) n sequence located in terminal regions of rearranged chromosomes, we suggest that the maintenance of multi-chromosomal associations may be evolutionarily advantageous for these species.
xmlui.dri2xhtml.METS-1.0.item-coverage San Francisco
Language English
Sponsor Fundacao de Amparo a Pesquisa do Estado de Sao Paulo
Grant number FAPESP: 2011/21643-1, 2013/11840-0
Date 2018
Published in Plos One. San Francisco, v. 13, n. 2, p. -, 2018.
ISSN 1932-6203 (Sherpa/Romeo, impact factor)
Publisher Public Library Science
Extent -
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000425604300027

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