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Karyotype Reorganization in the Hokou Gecko (Gekko hokouensis, Gekkonidae): The Process of Microchromosome Disappearance in Gekkota.

Srikulnath K, Uno Y, Nishida C, Ota H, Matsuda Y - PLoS ONE (2015)

Bottom Line: Ten pairs of G. hokouensis chromosomes [GHO1, 2, 3, Z(4), 6, 7, 8, 13, 14, and 15] showed highly conserved linkage homology with macrochromosomes and/or macrochromosome arms of the four Toxicofera species and corresponded to eight L. agilis macrochromosomes (LAG).However, GHO5, GHO9, GHO10, GHO11, and LAG6 were composed of chromosome segments that have a homology with Toxicofera microchromosomes, and no homology was found in the chromosomes between G. hokouensis and L. agilis.These results suggest that repeated fusions of microchromosomes may have occurred independently in each lineage of Gekkota and Lacertidae, leading to the disappearance of microchromosomes and appearance of small-sized macrochromosomes.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Animal Genetics, Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan; Laboratory of Animal Cytogenetics and Comparative Genomics, Department of Genetics, Faculty of Science, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, Thailand; Center for Advanced Studies in Tropical Natural Resources, National Research University-Kasetsart University (CASTNAR, NRU-KU), Kasetsart University, Bangkok, Thailand.

ABSTRACT
The Hokou gecko (Gekko hokouensis: Gekkonidae, Gekkota, Squamata) has the chromosome number 2n = 38, with no microchromosomes. For molecular cytogenetic characterization of the gekkotan karyotype, we constructed a cytogenetic map for G. hokouensis, which retains the ancestral karyotype of Gekkota, with 86 functional genes, and compared it with cytogenetic maps for four Toxicofera species that have many microchromosomes (Elaphe quadrivirgata, Varanus salvator macromaculatus, Leiolepis reevesii rubritaeniata, and Anolis carolinensis) and that for a lacertid species (Lacerta agilis) with only one pair of autosomal microchromosomes. Ten pairs of G. hokouensis chromosomes [GHO1, 2, 3, Z(4), 6, 7, 8, 13, 14, and 15] showed highly conserved linkage homology with macrochromosomes and/or macrochromosome arms of the four Toxicofera species and corresponded to eight L. agilis macrochromosomes (LAG). However, GHO5, GHO9, GHO10, GHO11, and LAG6 were composed of chromosome segments that have a homology with Toxicofera microchromosomes, and no homology was found in the chromosomes between G. hokouensis and L. agilis. These results suggest that repeated fusions of microchromosomes may have occurred independently in each lineage of Gekkota and Lacertidae, leading to the disappearance of microchromosomes and appearance of small-sized macrochromosomes.

No MeSH data available.


Chromosomal locations of the 18S–28S and 5S rRNA genes and (TTAGGG)n sequences in female Gekko hokouensis.(a) Hybridization pattern of FITC-labeled 18S–28S rRNA genes (green) and rhodamine-labeled 5S rRNA genes (red). Arrows indicate FISH signals of the 18S–28S rRNA genes, and arrowheads indicate signals of the 5S rRNA genes. (b) Hybridization pattern of FITC-labeled TTAGGG repeats (green) and rhodamine-labeled 5S rRNA genes (red). Arrows indicate signals of interstitial telomeric sites, and arrowheads indicate signals of the 5S rRNA genes. Scale bars represent 10 μm.
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pone.0134829.g002: Chromosomal locations of the 18S–28S and 5S rRNA genes and (TTAGGG)n sequences in female Gekko hokouensis.(a) Hybridization pattern of FITC-labeled 18S–28S rRNA genes (green) and rhodamine-labeled 5S rRNA genes (red). Arrows indicate FISH signals of the 18S–28S rRNA genes, and arrowheads indicate signals of the 5S rRNA genes. (b) Hybridization pattern of FITC-labeled TTAGGG repeats (green) and rhodamine-labeled 5S rRNA genes (red). Arrows indicate signals of interstitial telomeric sites, and arrowheads indicate signals of the 5S rRNA genes. Scale bars represent 10 μm.

Mentions: Fluorescence hybridization signals for the 18S–28S and 5S rRNA genes were localized to the pericentromeric region of chromosome 19 and proximal region of acrocentric chromosome 8, respectively (Fig 2A). Hybridization signals of TTAGGG repeats were observed at telomeric ends of all chromosomes. An interstitial telomeric site (ITS) was found at the pericentromeric region of the long arm of chromosome 14 (Fig 2B).


Karyotype Reorganization in the Hokou Gecko (Gekko hokouensis, Gekkonidae): The Process of Microchromosome Disappearance in Gekkota.

Srikulnath K, Uno Y, Nishida C, Ota H, Matsuda Y - PLoS ONE (2015)

Chromosomal locations of the 18S–28S and 5S rRNA genes and (TTAGGG)n sequences in female Gekko hokouensis.(a) Hybridization pattern of FITC-labeled 18S–28S rRNA genes (green) and rhodamine-labeled 5S rRNA genes (red). Arrows indicate FISH signals of the 18S–28S rRNA genes, and arrowheads indicate signals of the 5S rRNA genes. (b) Hybridization pattern of FITC-labeled TTAGGG repeats (green) and rhodamine-labeled 5S rRNA genes (red). Arrows indicate signals of interstitial telomeric sites, and arrowheads indicate signals of the 5S rRNA genes. Scale bars represent 10 μm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4524605&req=5

pone.0134829.g002: Chromosomal locations of the 18S–28S and 5S rRNA genes and (TTAGGG)n sequences in female Gekko hokouensis.(a) Hybridization pattern of FITC-labeled 18S–28S rRNA genes (green) and rhodamine-labeled 5S rRNA genes (red). Arrows indicate FISH signals of the 18S–28S rRNA genes, and arrowheads indicate signals of the 5S rRNA genes. (b) Hybridization pattern of FITC-labeled TTAGGG repeats (green) and rhodamine-labeled 5S rRNA genes (red). Arrows indicate signals of interstitial telomeric sites, and arrowheads indicate signals of the 5S rRNA genes. Scale bars represent 10 μm.
Mentions: Fluorescence hybridization signals for the 18S–28S and 5S rRNA genes were localized to the pericentromeric region of chromosome 19 and proximal region of acrocentric chromosome 8, respectively (Fig 2A). Hybridization signals of TTAGGG repeats were observed at telomeric ends of all chromosomes. An interstitial telomeric site (ITS) was found at the pericentromeric region of the long arm of chromosome 14 (Fig 2B).

Bottom Line: Ten pairs of G. hokouensis chromosomes [GHO1, 2, 3, Z(4), 6, 7, 8, 13, 14, and 15] showed highly conserved linkage homology with macrochromosomes and/or macrochromosome arms of the four Toxicofera species and corresponded to eight L. agilis macrochromosomes (LAG).However, GHO5, GHO9, GHO10, GHO11, and LAG6 were composed of chromosome segments that have a homology with Toxicofera microchromosomes, and no homology was found in the chromosomes between G. hokouensis and L. agilis.These results suggest that repeated fusions of microchromosomes may have occurred independently in each lineage of Gekkota and Lacertidae, leading to the disappearance of microchromosomes and appearance of small-sized macrochromosomes.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Animal Genetics, Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan; Laboratory of Animal Cytogenetics and Comparative Genomics, Department of Genetics, Faculty of Science, Kasetsart University, 50 Ngamwongwan, Chatuchak, Bangkok, Thailand; Center for Advanced Studies in Tropical Natural Resources, National Research University-Kasetsart University (CASTNAR, NRU-KU), Kasetsart University, Bangkok, Thailand.

ABSTRACT
The Hokou gecko (Gekko hokouensis: Gekkonidae, Gekkota, Squamata) has the chromosome number 2n = 38, with no microchromosomes. For molecular cytogenetic characterization of the gekkotan karyotype, we constructed a cytogenetic map for G. hokouensis, which retains the ancestral karyotype of Gekkota, with 86 functional genes, and compared it with cytogenetic maps for four Toxicofera species that have many microchromosomes (Elaphe quadrivirgata, Varanus salvator macromaculatus, Leiolepis reevesii rubritaeniata, and Anolis carolinensis) and that for a lacertid species (Lacerta agilis) with only one pair of autosomal microchromosomes. Ten pairs of G. hokouensis chromosomes [GHO1, 2, 3, Z(4), 6, 7, 8, 13, 14, and 15] showed highly conserved linkage homology with macrochromosomes and/or macrochromosome arms of the four Toxicofera species and corresponded to eight L. agilis macrochromosomes (LAG). However, GHO5, GHO9, GHO10, GHO11, and LAG6 were composed of chromosome segments that have a homology with Toxicofera microchromosomes, and no homology was found in the chromosomes between G. hokouensis and L. agilis. These results suggest that repeated fusions of microchromosomes may have occurred independently in each lineage of Gekkota and Lacertidae, leading to the disappearance of microchromosomes and appearance of small-sized macrochromosomes.

No MeSH data available.