• Environmental Mutagens and Carcinogens
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• v.16 no.1
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• pp.6-12
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• 1996

To investigate the clastogenicity of taxol and its precursor, 10-aleacetyl baccatin III, we performed chromosomal aberration assay with chinese hamster lung cells in vitro. The IC$_{50}$ values of taxol and 10-deacetyl baccatin III were determined as $1/16 \times 10^{-4}$ M (5.34 $\mu$g/ml) and $1 \times 10^{-2}$ M (560 $\mu$g/ml) in MTT assay, respectively. It means that the cytotoxicity of taxol revealed 100 times more cytotoxic than 10-deacetyl baccatin III in chinese hamster lung cell line. Nevertheless the strong positive genetic toxicity of taxol in the bone marrow micronucleus assay in vivo which was recently reported, we observed weak positive clastogenicity of taxoi only in the absence of metabolic activation system in the concentration ranges used in this experiment. Moreover, to clarify the involvement of metabolic fate of taxol because of its strong positive result in vivo, 10-deacetyl baccatin III which is a precursor in taxol synthesis, also subjected in chromosomal aberration assay in vitro. However, we observed no clastogenicity of 10-deacetyl baccatin III in this experiment. From above results, it was suggested that the esterification at C-13 appears to be relative for its genetic toxicity in chromosome aberration using chinese hamster lung cell in vitro.

• Molecules and Cells
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• v.25 no.2
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• pp.163-171
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• 2008

The genus Cynodon comprises ten species. The objective of this study was to evaluate the genetic diversity of Korean bermudagrasses at the morphological, cytological and molecular levels. Morphological parameters, the nuclear DNA content and ploidy levels were observed in 43 bermudagrass ecotypes. AFLP markers were evaluated to define the genetic diversity, and chromosome counts were made to confirm the inferred cytotypes. Nuclear DNA contents were in the ranges 1.42-1.56, 1.94-2.19, 2.54, and 2.77-2.85 pg/2C for the triploid, tetraploid, pentaploid, and hexaploid accessions, respectively. The inferred cytotypes were triploid (2n = 3x = 27), tetraploid (2n = 4x = 36), pentaploid (2n = 5x = 45), and hexaploid (2n = 6x = 54), but the majority of the collections were tetraploid (81%). Mitotic chromosome counts verified the corresponding ploidy levels. The fast growing fine-textured ecotypes had lower ploidy levels, while the pentaploids and hexaploids were coarse types. The genetic similarity ranged from 0.42 to 0.94 with an average of 0.64. UPGMA cluster analysis and principle coordinate analysis separated the ecotypes into 6 distinct groups. The genetic similarity suggests natural hybridization between the different cytotypes, which could be useful resources for future breeding and genetic studies.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.26-26
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• 2017

Seed germination stimulated by light is said to be photoblastism. Photoblastism has not been reported in cereal crops, especially in the rice, but Korean weedy rice was reported to have photoblastism and longer mesocotyl than cultivar. Photoblastic weedy rice (PBR) was used to identify QTLs for photoblastism and mesocotyl length. In previous works, QTLs for photoblastism, pbr1 and pbr12 were identified on chromosomes 1 and 12 using 124 F4 lines from a cross between Ilpum and PBR using bulked segregant analysis. Two QTLs for mesocotyl elongation, qMel-1 and qMel-3 were mapped on chromosomes 1 and 3 120 F8 lines from the same cross. Of interest, the RM8260-RM246 region of pbr1 overlapped with a region of qMel-1. To know whether these two QTLs are functionally related, 110 F3 lines were developed from a cross between Ilpum and CR7124. CR7124 having photoblastism and long mesocotyl was selected from 120 F8 lines. 95 F3 lines were measured for germination rate in a light and dark condition and mesocotyl length. Mesocotyl length and germination rate in the dark condition in F3 lines showed significant correlation (r = 0.7, P < 0.0001). 95 $F_3$ lines were genotyped with RM7419 on chromosome 1. ANOVA showed that RM7419 was tightly linked to QTLs for photoblastism as well as mesocotyl length on chromosome 1 (P < 0.0001) indicating the tight linkage of two QTLs. Fine mapping of the two QTL is underway to analyze their functional relationship.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.145-145
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• 2017

Foxglove aphid, Aulacorthum solani (Kaltenbach), is a Hemipteran insect that infected a wide variety of plants worldwide and caused serious yield losses in crops. The objective of this study was to identify the putative genes to foxglove aphid resistance in wild soybean, PI 366121 (Glycine soja Sieb. and Zucc.). One hundred and forty-one F4:8 recombinant inbred lines developed from a cross between susceptible variety, Williams 82 and foxglove aphid resistance wild soybean, PI 366121 were used. The two type of resistance response, antibiosis and antixenosis resistance were evaluated through choice and no-choice test, graded by the degree of total plant damage and primary infestation leaf damage; a genome-wide molecular linkage map was constructed with 29,898 single-nucleotide polymorphism markers utilizing a Axiom(R) 180K soyaSNP array. Using inclusive composite interval mapping analysis for foxglove aphid resistance, one major candidate QTL on chromosome 7 was identified. The major QTL on chromosome 7 showed both antixenosis and antibiosis resistance responses. The newly identified major QTL was consistent with previously reported QTL, Raso2, which showed around 5 times narrow down interval range with 8 candidate genes. Furthermore, total 1,115 soybean varieties including Glycine soja and Glycine max were exposed to germplasm screening, and 31 varieties, which showed significant antibiosis type foxglove aphid resistance were identified. This result could be useful in breeding for new foxglove aphid resistant soybean cultivars and developing novel insecticides.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.9
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• pp.1227-1231
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• 2002

A powerful tool for chicken transgenesis could be established by employing a germline chimera production through primordial germ cell transplantation. This study was conducted to examine whether foreign gene-transfected gonadal primordial germ cells (gPGCs) have a migration activity into the gonad after transfer to recipient embryos. In Experiment 1, gPGCs of Korean Ogol Chicken were retrieved from 5.5-day-old embryos and subsequently transferred to the dorsal aorta of 2.5-day-old White Leghorn embryos after being labeled with PKH26 fluorescent dye. To confirm migration activity after transplantation, recipient embryos were sacrificed and examined on 3 days after transfer. Sex determination was concomitantly undertaken to examine whether sex of recipient embryos could affect the migration activity of gPGCs. All of embryonic gonads examined showed positive signals with PKH26 fluorescence and W-chromosome specific band by polymerase chain reaction (PCR) was detected in male embryos when gPGCs with ZW chromosome were transferred to recipient embryos. In Experiment 2, retrieved gPGCs were transfected with LacZ gene-containing cytomegalovirus promoter ($pCMV{\beta}$) by electroporation and subsequently transferred to recipient embryos. LacZ gene expression was identified in the gonads of 6 or 10-day-old recipient embryos and hatched-chicks. A total of 20 embryos and 12 hatched-chicks were examined and 11 of them (10 embryos and one hatched chicken; 11/32=34.4%) expressed $\beta$-galactosidase, a marker substance of LacZ gene. The results of this study demonstrated that foreign gene-transfected gPGCs can migrate and settle down into the gonad after being transferred into the blood vessel of the recipient embryos. This established technique will contribute to developing a peer biotechnology for transgenic chicken.

• BMB Reports
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• v.41 no.10
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• pp.716-721
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• 2008

To explore the effects of deregulated expression of the EBNA1 binding protein 2 (EBP2) on cell growth, we generated human HEK293 stable clones constitutively expressing an EBP2-EGFP fusion protein. We found both RNA and protein levels of cyclin E1, a dominant oncoprotein, were elevated in the EBP2- EGFP stable clones. These findings were confirmed by flow cytometry bivariate analysis of cyclin expression versus DNA content. Moreover, the increase in p21 expression and the specific phosphorylation at Ser1981 of ATM and Ser15 of p53 were also observed in these stable clones, and these observations may explain the failure to observe an increase in Cdk2 kinase activity. In addition, after one year of passage culture, the EBP2-EGFP stable clones tended to lose 4 to 5 chromosomes per cell when compared to that of control cells. All of these findings provide a possible link between deregulated expression of EBP2 and tumor development.

• Journal of Microbiology and Biotechnology
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• v.16 no.2
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• pp.256-263
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• 2006

In the model legume Medicago truncatula, two mutants, sickle and sunn, exhibit morphologically and genetically distinct hypernodulation phenotypes. However, efforts to isolate the single recessive and single semidominant genes for sickle and sunn, respectively, by map-based cloning have so far been unsuccessful, partly due to the absence of clones that enable walks from linked marker positions. To help resolve these difficulties, a new bacterial artificial chromosome (BAC) library was constructed using BamHI-digested genomic fragments. A total of 23,808 clones were collected from ligation mixtures prepared with double-size-selected high-molecular-weight DNA. The average insert size was 116 kb based on an analysis of 88 randomly selected clones using NotI digestion and pulsed-field gel electrophoresis. About 18.5% of the library clones lacked inserts. The frequency of the BAC clones carrying chloroplast or mitochondrial DNA was 0.98% and 0.03%, respectively. The library represented approximately 4.9 haploid M. truncatula genomes. Hybridization of the BAC clone filters with a $C_{0}t-l$ DNA probe revealed that approximately 37% of the clones likely carried repetitive sequence-enriched DNA. An ordered array of pooled BAC DNA was screened by polymerase chain reactions using 13 sequence-characterized molecular markers that belonged to the eight linkage groups. Except for two markers, one to five positive BAC clones were obtained per marker. Accordingly, the sickle- and sunn-linked BAC clones identified herein will be useful for the isolation of these biotechnologically important genes. The new library will also provide clones that fill the gaps between preexisting BAC contigs, facilitating the physical mapping and genome sequencing of M. truncatula.

• Journal of Life Science
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• v.9 no.1
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• pp.69-75
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• 1999

Four species belonging to the Drosophila melanogaster complex were examined genetically and morphologically to analyze interspecific relationships. Insemination rates ranged from 96% to 99% within species crosses, but interspecific crosses among the four species exhibited a great variations in the frequency of successful matings. D. melanogaster females mated relatively well with males of other species and D. sechellia males were more successful in mating with females of other species. In the crosses among D. simulans, D. mauritiana and D. sechellia, hybrid flies were fertile in females, but sterile in males regardless of reciprocal matings. The phenogenetically relationship between this complex and their hybrids were investigated by the comparison of sex comb tooth number and genital arch of male. They were controlled by polygenic factors on the chromosome of both parents. The effects of temperature on viability of hybrids between D. melanogaster females and D. simulans males were investigated for detection of genes concerning the speciation. The temperature sensitivity of the hybrid was mainly controlled by genes located on the X chromosome of D. simulans males.

• Journal of The Korean Society of Grassland and Forage Science
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• v.17 no.1
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• pp.1-10
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• 1997

Unreduced (2n) gametes are meiotic products (pollen or egg) having a sporophytic (somatic) chromosome number, resulting from abnormalities during either microsporogenesis or megasporogenesis. They occur naturally at a low frequency in many plant species. Unreduced (2n) gametes in plants can be identified for four possible ways as follow i) pollen size and/or shape differences between haploid (n) and diploid (2n) pollen, ii) ploidy analysis (chromosome number) of progeny or meiotic analysis (presence of dyads andlor triads at the microspore stage), iii) progeny performance and fertility and iv) dosage of isozyme and DNA markers. Unreduced (2n) gametes can be an effective breeding tool in synthesizing new cultivars, providing a unique method to maximizing heterozygosity, i.e., transferring a large proportion of the non-additive genetic effects (intra- and inter- locus interactions) h m parent to offspring and can also be used to overcome infertility of interploidy crosses. Sexual polyploidization through 2n gametes has been a major route to the formation of naturally occurring polyploids. The three mechanisms of 2n pollen formation in potato have been discovered as follow: i) parallel spindles (ps) or tripolar spindles (ts), ii) premature cytokinesis (pc-I, pc-2) and iii) synaptic mutants (sy-2, sy-3, sy-4). Genetic analysis indicated that the mechanisms of 2n gamete formation were controlled by single recessive gene in potato, alfalfa, red clover, etc., and by two recessive genes in wheat. The use of 2n gametes which can efficiently transfer germplasm fiom wild relatives to cultivated species, especially fiom diploid to tetraploid could make a contribution to the improvement of germplasm base in breeding programs.

• Journal of Aquaculture
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• v.11 no.4
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• pp.457-463
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• 1998

An expression vector, pUC19N6-luc, containing nuclear matrix attachment region(MAR) isolated from Misgurnus mizolepis liver and control expressino vector, pUC19-luc, were constructed. After these vectors were transferred into CHSE-214 cell line by electroporation, the expression rate of luckferase gens, copy number of vectors and chromosome integration of vectors were analyzed by using assay of luciferase activity, PCR and Southern blotting. While the expression pattern of luciferase gene of pUC19-luc was shown in typicla transient ecpression pattern, that of pUC19N6-luc was highly increased at the 5 days after transfectrion. Although the cope number of pUC19N6-luc vector was higher than that of pUC19-luc vector, these vectors were integrated into chromosome at the same time point in the transfected CHSE-214 cells. In conclusion, the increase of luciferase gene expression of pUC19N6-luc was resulted from not the maintaining of the high copy number but the formation of transcription-favorable structure by MAR effect after chromosomal integration.