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Abstract

The cyprinid fish Alburnus alburnus possesses one of the largest supernumerary chromosomes in all vertebrates. In the present study, amplified fragment length polymorphism analyses (AFLP) and fluorescence in-situ hybridization (FISH) were performed in order to characterize these extraordinary chromosomes in detail. Sequence analysis of the B chromosome-specific DNA revealed a strong homology to a Drosophila Gypsy/Ty3 retrotransposon and also to a medaka (Oryzias latipes) one. The sequence is highly abundant on the B chromosome but undetectable in the normal A chromosome complement. It is also absent from the B chromosome of the closely related species, Rutilus rutilus, suggesting a specific spreading of the mobile element during evolution of the giant supernumerary chromosome within A. alburnus. Meitotic chromosomes were in-situ hybridized with the B chromosome-specific probe, documenting that the additional chromosome behaves as an autopaired ring chromosome in diakineses. Our results suggest that the supernumerary chromosome of A. alburnus is not derived from the normal chromosome complement but has evolved independently.

Karyological analyses of Pseudhymenochirus merlini and Hymenochirus boettgeri provide new insights into the chromosome evolution in the anuran family Pipidae

“…However, the unpaired chromosome of H. boettgeri is larger than the regular chromosomes of the last two pairs. This aspect, though unusual, has been displayed by various taxa, for example in the Korean field mouse Apodemus peninsulae (Thomas, 1907) (Karamysheva et al, 2002;Trifonov et al, 2002), in the cyprinid fish Alburnus alburnus (Linnaeus, 1758) (Ziegler et al, 2003;Schmid et al, 2006) and, among anurans, in the hylid tree frog Hypsiboas albopunctatus (Spix, 1824) (Gruber et al, 2007(Gruber et al, , 2014Ferro et al, 2012). Thus, the unpaired element of two males of H. boettgeri can be regarded as a B chromosome, which suggests that at least one of their parents possessed and transmitted it.…”

Delimiting the Origin of a B Chromosome by FISH Mapping, Chromosome Painting and DNA Sequence Analysis in Astyanax paranae (Teleostei, Characiformes)

“…In fish, only satellite DNA, 45S rDNA and transposable elements had previously been found in the B chromosomes of Astyanax scabripinnis [33], Prochilodus lineatus [66], Haplochromis obliquidens [36], Astatotilapia latifasciata [67], Alburnus alburnus [68], while active nucleolar sites were observed in the B chromosomes of Moenkausia sanctaefilomenae [69]. Here, we show the first evidence of histone protein genes allocated in a fish B chromosome, a fact that had previously been reported only in the grasshoppers Locusta migratoria [21] and Rhammatocerus brasiliensis [22].…”

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

“…Most authors accept the hypothesis that these chromosome segments emerge from elements of the standard complement (Camacho and Cabrero 1987;Palomeque et al 1993;Jesus et al 2003;Artoni et al 2006). Other theories state that the B chromosome is not derived from such elements and a heterologous origin is proposed to explain the emergence of the giant B chromosome in Alburnus alburnus, in which this chromosome is made up of dispersed retrotransposon repetitive DNA (Ziegler et al 2003).…”