| Autor: |
Silva DMZA; Universidade Estadual Paulista (UNESP), Instituto de Biociências de Botucatu, Departamento de Biologia Estrutural e Funcional, Botucatu, SP, Brazil., Araya-Jaime C; Universidad de La Serena, Instituto de Investigación Multidisciplinar en Ciencia y Tecnología, La Serena, Chile.; Universidad de La Serena, Departamento de Biología, Laboratorio de Genética y Citogenética Vegetal, La Serena, Chile., Yamashita M; Hokkaido University, Faculty of Science, Department of Biological Sciences, Laboratory of Reproductive & Developmental Biology, Sapporo, Japan., Vidal MR; Universidade Estadual Paulista (UNESP), Instituto de Biociências de Botucatu, Departamento de Biologia Estrutural e Funcional, Botucatu, SP, Brazil., Oliveira C; Universidade Estadual Paulista (UNESP), Instituto de Biociências de Botucatu, Departamento de Biologia Estrutural e Funcional, Botucatu, SP, Brazil., Porto-Foresti F; Universidade Estadual Paulista (UNESP), Faculdade de Ciências, Departamento de Ciências Biológicas, Bauru, SP, Brazil., Artoni RF; Universidade Federal de São Carlos (UFSCAR), Departamento de Genética e Evolução, São Carlos, SP, Brazil.; Universidade Estadual de Ponta Grossa (UEPG), Departamento de Biologia Estrutural, Molecular e Genética, Ponta Grossa, PR, Brazil., Foresti F; Universidade Estadual Paulista (UNESP), Instituto de Biociências de Botucatu, Departamento de Biologia Estrutural e Funcional, Botucatu, SP, Brazil. |
| Abstrakt: |
B chromosomes are non-essential additional genomic elements present in several animal and plant species. In fishes, species of the genus Psalidodon (Characiformes, Characidae) harbor great karyotype diversity, and multiple populations carry different types of non-essential B chromosomes. This study analyzed how the dispensable supernumerary B chromosome of Psalidodon paranae behaves during meiosis to overcome checkpoints and express its own meiosis-specific genes. We visualized the synaptonemal complexes of P. paranae individuals with zero, one, or two B chromosomes using immunodetection with anti-medaka SYCP3 antibody and fluorescence in situ hybridization with a (CA)15 microsatellite probe. Our results showed that B chromosomes self-pair in cells containing only one B chromosome. In cells with two identical B chromosomes, these elements remain as separate synaptonemal complexes or close self-paired elements in the nucleus territory. Overall, we reveal that B chromosomes can escape meiotic silencing of unsynapsed chromatin through a self-pairing process, allowing expression of their own genes to facilitate regular meiosis resulting in fertile individuals. This behavior, also seen in other congeneric species, might be related to their maintenance throughout the evolutionary history of Psalidodon. |
