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. 2013 Nov 22;6(1):51.
doi: 10.1186/1755-8166-6-51.

Karyotype and cytogenetic mapping of 9 classes of repetitive DNAs in the genome of the naked catfish Mystus bocourti (Siluriformes, Bagridae)

Weerayuth Supiwong  1 , Thomas Liehr, Marcelo B Cioffi, Arunrat Chaveerach, Nadezda Kosyakova, Krit Pinthong, Tawatchai Tanee, Alongklod Tanomtong
Affiliations

Karyotype and cytogenetic mapping of 9 classes of repetitive DNAs in the genome of the naked catfish Mystus bocourti (Siluriformes, Bagridae)

Weerayuth Supiwong et al. Mol Cytogenet. .

Abstract

Background: In the present study, conventional and molecular cytogenetic studies were performed in the naked catfish Mystus bocourti (Siluriformes, Bagridae). Besides the conventional Giemsa staining, fluorescence in situ hybridization (FISH) using nine classes of repetitive DNAs namely 5S and 18S rDNAs, U2 snRNA, the microsatellites (CA)15 and (GA)15, telomeric repeats, and the retrotransposable elements Rex1, 3 and 6. was also performed.

Results: M. bocourti had 2n = 56 chromosomes with a karyotype composed by 11 m + 11 sm + 6 st/a and a fundamental number (NF) equal to 100 in both sexes. Heteromorphic sex chromosome cannot be identified. The U2 snRNA, 5S and 18S rDNA were present in only one pair of chromosomes but none of them in a syntenic position. Microsatellites (CA)15 and (GA)15 showed hybridization signals at subtelomeric regions of all chromosomes with a stronger accumulation into one specific chromosomal pair. FISH with the telomeric probe revealed hybridization signals on each telomere of all chromosomes and interstitial telomeric sites (ITS) were not detected. The retrotransposable elements Rex1, 3 and 6 were generally spread throughout the genome.

Conclusions: In general, the repetitive sequences were not randomly distributed in the genome, suggesting a pattern of compartmentalization on the heterochromatic region of the chromosomes. Little is known about the structure and organization of bagrid genomes and the knowledge of the chromosomal distribution of repetitive DNA sequences in M. bocourti represents the first step for achieving an integrated view of their genomes.

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Figures

Figure 1
Figure 1
Collection sites of Mystus bocourti. (A) Map of Thailand indicating the collection sites and (B) an individual of Mystus bocourti. Bar = 5 cm.
Figure 2
Figure 2
Karyotype of Mystus bocourti arranged from Giemsa stained chromosomes. Bar = 5 μm.
Figure 3
Figure 3
Fluorescence in situ hybridization with various repetitive DNA probes on metaphase chromosomes of the naked catfish Mystus bocourti. Bar = 5 μm.
See this image and copyright information in PMC

References

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