• The Korean Journal of Zoology
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• v.39 no.1
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• pp.75-88
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• 1996

OTF9-63 (OTF9) and P19S1O1A1 (P19) embryonal carcinoma (EC) cells were examined for their ability to produce the readivation of inactive X chromosomes from somatic cells. They were hybridized with various somatic cells and resulting HATr EC-somatic cell clones were analysed for their morphology, chromosomal replication pafterns and expression proffies of X-linked and distantiy located genes, Hprt and Pgk-1. The results demonstrated that 0RF9 cells could reactivate the inactive X chromosome whereas P19 cells could not. In adition, EC-somatic cell hybrids tended to reduce the number of sex chromosomes in long-term culture, resulting m 1:2 ratio of sex chromosomes to autosomes The use of EC cell hybrids provides an experimental system for studying the mechanism(s) of the X-reactivatio that is initiated and maintained from meiotic prophase of oogenesis to early embryogenesis.

• Toxicological Research
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• v.33 no.4
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• pp.315-323
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• 2017

Preconceptual sex selection is still a highly debatable process whereby X- and Y-chromosome-bearing spermatozoa are isolated prior to fertilization of the oocyte. Although various separation techniques are available, none can guarantee 100% accuracy. The aim of this study was to separate X- and Y-chromosome-bearing spermatozoa using methods based on the viability difference between the X- and Y-chromosome-bearing spermatozoa. A total of 18 experimental semen samples were used, written consent was obtained from all donors and results were analysed in a blinded fashion. Spermatozoa were exposed to different pH values (5.5, 6.5, 7.5, 8.5, and 9.5), increased temperatures ($37^{\circ}C$, $41^{\circ}C$, and $45^{\circ}C$) and ROS level ($50{\mu}M$, $750{\mu}M$, and $1,000{\mu}M$). The live and dead cell separation was done through a modified swim-up technique. Changes in the sex-chromosome ratio of samples were established by double-label fluorescent in situ hybridization (FISH) before and after processing. The results indicated successful enrichment of X-chromosome-bearing spermatozoa upon incubation in acidic media, increased temperatures, and elevated $H_2O_2$. This study demonstrated the potential role for exploring the physiological differences between X-and Y-chromosome-bearing spermatozoa in the development of preconceptual gender selection.

• Animal cells and systems
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• v.1 no.2
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• pp.355-361
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• 1997

We have screened available chromosomal deficiencies on the X chromosome for genetic loci whose zygotic expression is required for body-wall muscle development during embryogenesis in Caenorhabditis elegans. Previously, it had been reported that no sign of muscle development was detected in nullo-X embryos arrested at an early stage of embryogenesis. Based on this observation, it has been suggested that genetic loci exist on the X chromosome whose zygotic expression is essential for body-wall muscle formation. In order to identify such myogenic loci, 9 chromosomal deficiencies covering approximately 45% of the X chromosome have been tested. Homozygous embryos from these deficiency strains were collected and terminal phenotypes of arrested embryos were observed by Nomarski microscopy. As a secondary assay, monoclonal antibodies against two myosin heavy chain (MHC) isoforms, the products of the myo-3 and unc-54 genes, were used to detect body-wall muscle differentiation. All the homozygous deficiency embryos were positively stained with both MHC antibodies and muscle twitching movement was observed in most cases. Combined with previously analyzed deficiencies, our deficiency screen has covered approximately 70% of the X chromosome. We conclude that the regions covered by the available deficiencies on the X chromosome do not include any myogenic locus required for body-wall muscle formation. Alternatively, the possibility that nullo-X embryo may not form body-wall muscle due to a general failure to differentiate during embryogenesis remains to be tested.

• Korean Journal of Plant Resources
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• v.31 no.5
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• pp.515-521
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• 2018

This was carried out to develop a chromosome-doubled (12x) persimmon that will be used as a crossing parent to select seedless persimmon cultivars with the change of the consumption trend recently. To obtain a chromosome-doubled (12x) persimmon, colchicine was applied at the meristem of seedlings in vitro derived from cross among hexaploid persimmon (Diopyros kaki Thunb.). These were treated with 0.03%, 0.05% and 0.1% colchicine respectively for doubling chromosome, and it was most effective at the concentration of 0.05% colchicine. After colchicine treatment, we conducted tests to elucidate conditions for inducing shoot and root development. As the result, the shoots grew best when cultivated at 1/2MS media plus 10 and $30{\mu}M$ zeatin respectively, and the roots grew best when cultivated at 1/2MS media after dipping for 5 seconds at 10 mM NAA+5% DMSO. We also compared seedlings that have chromosome (6x) do not doubled and crossing parents (6x) and chromosome-doubled seedlings (12x). As the result, these chromosome-doubled seedlings (12x) showed lower stomatal density and larger stomatal size.

• Environmental Mutagens and Carcinogens
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• v.7 no.2
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• pp.103-111
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• 1987

The effects of LET (linear energy transfer) of radiation on the induction of somatic chromosome mutations or gene mutations of Drosophila melanogaster were studied. For detecting somatic chromosome mutations and gene mutations, Drosophila wing spot system and eye-color spot system were used, respectively. The frequencies of somatic chromosome mutations or gene mutations induced after third instar larval treatment with 23 MeV neutrons, thermal neutrons, X-rays were examined. From these data, the RBE(relative biological effectiveness) values of 23 MeV neutrons relative to X-rays for induction of somatic chromosome mutations or gene mutations were calculated. The present results suggest that high LET radiations are efficient than X-ray in producing not only somatic chromosome mutations but also gene mutations.

• BMB Reports
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• v.46 no.6
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• pp.310-315
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• 2013

The gene order on the X chromosome of eutherians is generally highly conserved, although an increase in the rate of rearrangement has been reported in the rodent lineage. Conservation of the X chromosome is thought to be caused by selection related to maintenance of dosage compensation. However, we herein reveal that the cattle (Btau4.0) lineage has experienced a strong increase in the rate of X-chromosome rearrangement, much stronger than that previously reported for rodents. We also show that this increase is not matched by a similar increase on the autosomes and cannot be explained by assembly errors. Furthermore, we compared the difference in two cattle genome assemblies: Btau4.0 and Btau6.0 (Bos taurus UMD3.1). The results showed a discrepancy between Btau4.0 and Btau6.0 cattle assembly version data, and we believe that Btau6.0 cattle assembly version data are not more reliable than Btau4.0.

• Journal of Life Science
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• v.11 no.2
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• pp.81-82
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• 2001

The human ribosomal protein 54 genes, RPS4X and RPS4Y are located on the X and Y chromosomes. They have been postulated as candidate for Turner syndrome which was characterized by gonadal dysgenesis, short stature, and various external and internal anomalies. Using the BLAST search program, we identified sixteen RPS4 pseudogenes from the human genome and analyzed them phylogenetically. The RPS4-C12-1, C12-2, and C12-3 pseudogenes from chromosome 12 have been evolved independently during hominid evolution. The RPS4X gene from X chromosome it closely related to the RPS4-C12-2 from chromosome 12 and RPS4-C5 from chromosome 5, whereas the RPS4Y gene is very closely related to RPS4-C16 from chromosome 16. The exact mapping of the RPS4 pseudogene family was peformed, indicating that the RPS4 pseudogene family was mapped on human chromosomes 1, 2, 5, 6, 8, 10, 11, 12, 13, 16, 18, 19 and 20. Taken together, the precise chromosomal localization and phylegenetic relationship of the RPS4 pseudo-genes could be of great use in further study for understanding the Turner syndrome.

• The Korean Journal of Zoology
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• v.15 no.3
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• pp.95-100
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• 1972

Dose response and time dependence of unscheduled DNA synthesis induced by X-rays were measured to determine if any correlation exists between unscheduled DNA synthesis, modal chromosome number, chromosome exchange and mitotic activity in four mammalian cell strains. Unscheduled DNA synthesis occurred in all strains studied. The rate was dose-dependent and strain-specific. Only HeLa $S_3$ showed a staturated dose response after 4, 000 R, other cells were linearly proportional to dose increases. Time dependence of unscheduled DNA synthesis was completed within 2 hours after irradiation regardless of cell strains. Unscheduled DNA synthesis was not directly related to modal chromosome number, total exchange rate and mitotic activity. Mitotic activity and chromosome exchange were both dose-dependent, but the rates of them were inversely related.

• Genomics & Informatics
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• v.3 no.4
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• pp.154-158
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• 2005

Germ-line mutations of the BRCA1 gene confer an increased risk for breast and ovarian cancers. BRCA1 in female cells is directly related with the maintenance of the inactive X chromosome (Xi). The effect by the loss of the BRCA1 function on the X chromosome gene expression remains unclear in cancer cells. We attempted to investigate the expression pattern of the X-linked genes by performing BRCA1 knockdown via RNA interference in the MCF7 breast cancer cell line. The transcriptional and translational levels of BRCA1 were decreased over 95% in the MCF7 cells after BRCA1 knockdown. The expression patterns of one hundred ninety X-linked genes were profiled by the X chromosome-specific cDNA arrays. A total of seven percent of the X-linked genes (14/190) were aberrantly expressed by over 2-fold in the MCF7-BRCA1 knockdown cells, which contained two up-regulated genes (2/190, 1 %) and 12 down-regulated genes (12/190, 6.3%). It is interesting that 72% of the aberrantly expressed X-linked genes were located on the Xq (10/14,) region. Our data suggests that BRCA1 may not be important to maintain X chromosome inactivation in cancer because the BRCA1 knockdown did increase the expression of the only one percent of X-linked genes in the human breast cancer cells.

• Korean Journal of Plant Taxonomy
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• v.41 no.3
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• pp.215-222
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• 2011

Various aneuploidy and polyploidy have been reported in the genus Aconitum L. (ca. 300 species worldwide, Ranunculaceae), and there is a demonstrated association between major lineage diversification and polyploidy. This study reports chromosome counts of eight Aconitum from Korea, including the first counts for A. japonicum Thunb. subsp. napiforme ($H. L{\acute{e}}v.$ & Vaniot) Kadota (2n = 32) and A. longecassidatum Nakai (2n = 16). The study also includes chromosome numbers for two taxa on the Critically Endangered species list in Korea. Among Korean native species, chromosome numbers in Aconitum subgenus Aconitum range from 2n = 16 to 2n = 64 with diverse levels of polyploidy (2x, 4x, and 8x), whereas Aconitum subg. Lycoctonum exhibits only diploids (2n = 16). Greater chromosome number diversity in subg. Aconitum than subg. Lycoctonum might explain higher species diversity within the former subgenus (more than 250 species worldwide). Investigating chromosome number diversity of Aconitum in a phylogenetic framework will be a critical step to understand species richness of the genus.