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

Autor(es)

Mattos, Viviane Fagundes ^[1] ; Carvalho Currency, Leonardo Sousa ^{[2, 3]} ; Carvalho, Marcos Andre ^[4] ; Schneider, Marielle Cristina ^[5]

Afiliação do(s) autor(es)

^[1] Univ Estadual Paulista, UNESP, Dept Biol, Sao Paulo - Brazil

^[2] Univ Fed Minas Gerais, Posgrad Zool, Belo Horizonte, MG - Brazil

^[3] Univ Fed Piaui, UFPI, Campus Almicar Ferreira Sobral Floriano, Piaui - Brazil

^[4] Univ Fed Mato Grosso, Dept Biol & Zool, Cuiaba, Mato Grosso - Brazil

^[5] Univ Fed Sao Paulo, UNIFESP, Dept Ecol & Biol Evolut, Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: PLoS One; v. 13, n. 2 FEB 21 2018.
• Citações Web of Science: 1

Resumo

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. (AU)

• Processo FAPESP: 11/21643-1 - Meiose em escorpiões (Arachnida): modelo para compreender a evolução em espécies com cromossomos aquiasmáticos
• Beneficiário: Marielle Cristina Schneider
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
• Processo FAPESP: 13/11840-0 - Análise da variabilidade cariotípica e do comportamento dos cromossomos na meiose de escorpiões do gênero Tityus (Buthidae)
• Beneficiário: Viviane Fagundes de Mattos
• Modalidade de apoio: Bolsas no Brasil - Doutorado