Complex meiotic configuration of the holocentric chromosomes: the intriguing case of the scorpion Tityus bahiensis

Complex meiotic configuration of the holocentric chromosomes: the intriguing case of the scorpion Tityus bahiensis

Author Schneider, Marielle Cristina Autor UNIFESP Google Scholar
Zacaro, Adilson Ariza Google Scholar
Pinto-da-Rocha, Ricardo Google Scholar
Candido, Denise Maria Google Scholar
Cella, Doralice Maria Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Univ Estadual Paulista
Universidade Federal de Viçosa (UFV)
Universidade de São Paulo (USP)
Inst Butantan
Abstract Mitotic and meiotic chromosomes of Tityus bahiensis were investigated using light (LM) and transmission electron microscopy (TEM) to determine the chromosomal characteristics and disclose the mechanisms responsible for intraspecific variability in chromosome number and for the presence of complex chromosome association during meiosis. This species is endemic to Brazilian fauna and belongs to the family Buthidae, which is considered phylogenetically basal within the order Scorpiones. in the sample examined, four sympatric and distinct diploid numbers were observed: 2n = 5, 2n = 6, 2n = 9, and 2 = 10. the origin of this remarkable chromosome variability was attributed to chromosome fissions and/or fusions, considering that the decrease in chromosome number was concomitant with the increase in chromosome size and vice versa. the LM and TEM analyses showed the presence of chromosomes without localised centromere, the lack of chiasmata and recombination nodules in male meiosis, and two nucleolar organiser regions carrier chromosomes. Furthermore, male prophase I cells revealed multivalent chromosome associations and/or unsynapsed or distinctly associated chromosome regions (gaps, less-condensed chromatin, or loop-like structure) that were continuous with synapsed chromosome segments. All these data permitted us to suggest that the chromosomal rearrangements of T. bahiensis occurred in a heterozygous state. A combination of various factors, such as correct disjunction and balanced segregation of the chromosomes involved in complex meiotic pairing, system of achiasmate meiosis, holocentric nature of the chromosomes, population structure, and species dispersion patterns, could have contributed to the high level of chromosome rearrangements present in T. bahiensis.
Keywords achiasmate meiosis
cytogenetic
diploid number
nucleolar material
synaptonemal complex
Language English
Sponsor Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Grant number FAPESP: 06/53275-3
Date 2009-10-01
Published in Chromosome Research. Dordrecht: Springer, v. 17, n. 7, p. 883-898, 2009.
ISSN 0967-3849 (Sherpa/Romeo, impact factor)
Publisher Springer
Extent 883-898
Origin http://dx.doi.org/10.1007/s10577-009-9076-4
Access rights Closed access
Type Article
Web of Science ID WOS:000271722100005
URI http://repositorio.unifesp.br/handle/11600/31853

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