Origin of B chromosomes in (Characiformes, Crenuchidae) and its relationship with supernumerary chromosomes in other species.

B chromosomes are apparently dispensable components found in the genomes of many species that are mainly composed of repetitive DNA sequences. Among the numerous questions concerning B chromosomes, the origin of these elements has been widely studied. To date, supernumerary chromosomes have been identified in approximately 60 species of fish, including species of the genus Reinhardt, 1867 in which these elements appear to have independently originated.

A Glimpse into the Satellite DNA Library in Characidae Fish (Teleostei, Characiformes).

Satellite DNA (satDNA) is an abundant fraction of repetitive DNA in eukaryotic genomes and plays an important role in genome organization and evolution. In general, satDNA sequences follow a concerted evolutionary pattern through the intragenomic homogenization of different repeat units. In addition, the satDNA library hypothesis predicts that related species share a series of satDNA variants descended from a common ancestor species, with differential amplification of different satDNA variants.

Meiotic behavior and H3K4m distribution in B chromosomes of Characidium gomesi (Characiformes, Crenuchidae).

Characidium gomesi Travasso, 1956 specimens from the Pardo River have up to four heterochromatic supernumerary chromosomes, derived from the sex chromosomes. To access the meiotic behavior and distribution of an active chromatin marker, males and females of Characidium gomesi with two or three B chromosomes were analyzed. Mitotic chromosomes were characterized using C-banding and FISH with B chromosome probes.

Surface-spreading technique of meiotic cells and immunodetection of synaptonemal complex proteins in teleostean fishes.

Background: Different moderrn methodologies are presently available to analyze meiotic chromosomes. These methods permit investigation of the behavior of chromosomes in the normal complement and of sex and B chromosomes, two special types of chromosomes that are associated with the A complement and are present in many organisms, including fishes. However, meiotic studies are still scarce in fishes, considering the wide number of species in this group.

Single origin of sex chromosomes and multiple origins of B chromosomes in fish genus Characidium.

Chromosome painting with DNA probes obtained from supernumerary (B) and sex chromosomes in three species of fish genus Characidium (C. gomesi, C. pterostictum and C.