Meiotic behavior, transmission and active genes of B chromosomes in the cichlid Astatotilapia latifasciata: new clues about nature, evolution and maintenance of accessory elements
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Data
2022-07-01
Autores
Cardoso, Adauto Lima [UNESP]
Venturelli, Natália Bortholazzi [UNESP]
da Cruz, Irene
de Sá Patroni, Fábio Malta [UNESP]
de Moraes, Diogo [UNESP]
de Oliveira, Rogério Antonio [UNESP]
Benavente, Ricardo
Martins, Cesar [UNESP]
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Resumo
Supernumerary B chromosomes (Bs) are dispensable genetic elements widespread in eukaryotes and are poorly understood mainly in relation to mechanisms of maintenance and transmission. The cichlid Astatotilapia latifasciata can harbor Bs in a range of 0 (named B −) and 1–2 (named B +). The B in A. latifasciata is rich in several classes of repetitive DNA sequences, contains protein coding genes, and affects hosts in diverse ways, including sex-biased effects. To advance in the knowledge about the mechanisms of maintenance and transmission of B chromosomes in A. latifasciata, here, we studied the meiotic behavior in males and transmission rates of A. latifasciata B chromosome. We also analyzed structurally and functionally the predicted B chromosome copies of the cell cycle genes separin-like, tubb1-like and kif11-like. We identified in the meiotic structure relative to the B chromosome the presence of proteins associated with Synaptonemal Complex organization (SMC3, SYCP1 and SYCP3) and found that the B performs self-pairing. These data suggest that isochromosome formation was a step during B chromosome evolution and this element is in a stage of diversification of the two arms keeping the self-pairing behavior to protect the A chromosome complement of negative effects of recombination. Moreover, we observed no occurrence of B-drive and confirmed the presence of cell cycle genes copies in the B chromosome and their transcription in encephalon, muscle and gonads, which can indicates beneficial effects to hosts and contribute to B maintenance.
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Active B-genes, Heterotic model, Supernumerary chromosome, Synaptonemal complex
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Molecular Genetics and Genomics, v. 297, n. 4, p. 1151-1167, 2022.