New insights on the origin of B chromosomes in Astyanax scabripinnis obtained by chromosome painting and FISH

• DOI: 10.1007/s10709-011-9611-z
• Publication Date: 2011-09-26T03:50:17Z
• Authors: Marcelo Ricardo V...; Helena Flávia de ...; Jonathan Pena Castro; Mara Cristina de ...; Luiz Antonio Carl...; Orlando Moreira-F...; Juan Pedro M. Cam...; Roberto Ferreira ...
• Keywords: Isochromosome; B chromosome; Chromosome 4; Chromosome 16; Hybridization probe

Chromosome painting (CP) with a probe of B chromosome obtained by microdissection and fluorescence in situ hybridization (FISH) with probes of As51 satellite DNA, C( o )t-1 DNA, and 18S and 5S rDNA confirmed sharing of some repetitive DNA but not rDNA between A and B chromosomes in the fish Astyanax scabripinnis. Meiotic analysis revealed a pachytene B chromosome bivalent nearly half the size of its mitotic configuration, suggesting a self-pairing of B chromosome arms. Such an isochromosome nature of somatic B chromosome was further evidenced by CP and FISH. All the findings obtained suggest (i) intraspecific origin of B chromosome, and (ii) evolutionary enrichment of repetitive DNA classes, especially those contained in the C( o )t-1 and the As51 probes, in B chromosome. However, the precise origin of B chromosome in the present species remains to be elucidated by further molecular cytogenetic analysis because of painting of some A chromosome regions with the B chromosome-derived probe.