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Mol. Cells 2005; 19(3): 436-444

Published online June 30, 2005

© The Korean Society for Molecular and Cellular Biology

Characterization of rDNAs and Tandem Repeats in the Heterochromatin of Brassica rapa

Ki-Byung Lim, Hans Jong, Tae-Jin Yang, Jee-Young Park, Soo-Jin Kwon, Jung Sun Kim, Myung-Ho Lim, Jin A Kim, Mina Jin, Yong-Moon Jin, Seog Hyung Kim, Yong Pyo Lim, Jae-Wook Bang, Ho-Il Kim, Beom-Seok Park

Abstract

We describe the morphology and molecular organization of heterochromatin domains in the interphase nuclei, and mitotic and meiotic chromosomes, of Brassica rapa, using DAPI staining and fluorescence in situ hybridization (FISH) of rDNA and pericentromere tandem repeats. We have developed a simple method to distinguish the centromeric regions of mitotic metaphase chromosomes by prolonged irradiation with UV light at the DAPI excitation wavelength. Application of this bleached DAPI band (BDB) karyotyping method to the 45S and 5S rDNAs and 176 bp centromere satellite repeats distinguished the 10 B. rapa chromosomes. We further characterized the centromeric repeat sequences in BAC end sequences. These fell into two classes, CentBr1 and CentBr2, occupying the centromeres of eight and two chromosomes, respectively. The centromere satellites encompassed about 30% of the total chromosomes, particularly in the core centromere blocks of all the chromosomes. Interestingly, centromere length was inversely correlated with chromosome length. The morphology and molecular organization of heterochromatin domains in interphase nuclei, and in mitotic and meiotic chromosomes, were further characterized by DAPI staining and FISH of rDNA and CentBr. The DAPI fluorescence of interphase nuclei revealed ten to twenty conspicuous chromocenters, each composed of the heterochromatin of up to four chromosomes and/or nucleolar organizing regions.

Keywords BDB, Centromeric Repeat, Chromocentre, Constitutive Heterochromatin, FISH.

Article

Research Article

Mol. Cells 2005; 19(3): 436-444

Published online June 30, 2005

Copyright © The Korean Society for Molecular and Cellular Biology.

Characterization of rDNAs and Tandem Repeats in the Heterochromatin of Brassica rapa

Ki-Byung Lim, Hans Jong, Tae-Jin Yang, Jee-Young Park, Soo-Jin Kwon, Jung Sun Kim, Myung-Ho Lim, Jin A Kim, Mina Jin, Yong-Moon Jin, Seog Hyung Kim, Yong Pyo Lim, Jae-Wook Bang, Ho-Il Kim, Beom-Seok Park

Abstract

We describe the morphology and molecular organization of heterochromatin domains in the interphase nuclei, and mitotic and meiotic chromosomes, of Brassica rapa, using DAPI staining and fluorescence in situ hybridization (FISH) of rDNA and pericentromere tandem repeats. We have developed a simple method to distinguish the centromeric regions of mitotic metaphase chromosomes by prolonged irradiation with UV light at the DAPI excitation wavelength. Application of this bleached DAPI band (BDB) karyotyping method to the 45S and 5S rDNAs and 176 bp centromere satellite repeats distinguished the 10 B. rapa chromosomes. We further characterized the centromeric repeat sequences in BAC end sequences. These fell into two classes, CentBr1 and CentBr2, occupying the centromeres of eight and two chromosomes, respectively. The centromere satellites encompassed about 30% of the total chromosomes, particularly in the core centromere blocks of all the chromosomes. Interestingly, centromere length was inversely correlated with chromosome length. The morphology and molecular organization of heterochromatin domains in interphase nuclei, and in mitotic and meiotic chromosomes, were further characterized by DAPI staining and FISH of rDNA and CentBr. The DAPI fluorescence of interphase nuclei revealed ten to twenty conspicuous chromocenters, each composed of the heterochromatin of up to four chromosomes and/or nucleolar organizing regions.

Keywords: BDB, Centromeric Repeat, Chromocentre, Constitutive Heterochromatin, FISH.

Mol. Cells
Nov 30, 2021 Vol.44 No.11, pp. 781~860
COVER PICTURE
3D quantitative images of the vesicular structure and the nucleolus using label free optical diffraction tomography (Kim et al., pp. 851-860).

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