• The Korean Journal of Malacology
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• v.7 no.1
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• pp.12-29
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• 1991

The chromosome numbers and the karyotypes of seven species in Unionidae are reported, using air drying in gonad. In seven species, the chromosome number of 38(2n) was counted. The mitotic chormosomes of A. arcaeformis flavotincta, A. woodiana and L. gottschei hd 7 pairs of metacentric and 12 pairs of submetacenrtic chromosomes, U. douglasiae had 6 pairs of metacentrics, 13 pairs of submetacentrics, U. douglasiae sinuolatus had 4 metacentric pairs and 15 submetacentric pairs, L. acrorhyncha had 5 metacentric pairs and 14 submetaacentric pairs, and S. triangularis had 5 mdtacenrtric pairs, 13 submetacentric pairs and 1 pair of subtelocentric chromosomes. The size of chromosomes of A. woodiana was the longest in length and L. gottschei was the shortest. The sexual difference of chromosomes was not observed.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.7
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• pp.938-943
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• 2016

Development of body hair is an important physiological and cellular process that leads to better adaption in tropical environments for dairy cattle. Various studies suggested a major gene and, more recently, associated genes for hairy locus in dairy cattle. Main aim of this study was to i) employ a variant of the discordant sib pair model, in which half sibs from the same sires are randomly sampled using their affection statues, ii) use various single marker regression approaches, and iii) use whole genome regression approaches to dissect genetic architecture of the hairy gene in the cattle. Whole and single genome regression approaches detected strong genomic signals from Chromosome 23. Although there is a major gene effect on hairy phenotype sourced from chromosome 23: whole genome regression approach also suggested polygenic component related with other parts of the genome. Such a result could not be obtained by any of the single marker approaches.

• Journal of the Korean Society of Tobacco Science
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• v.7 no.1
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• pp.93-96
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• 1985

This study was conducted to establish the maternal haploid method for the practical breeding of M tabacum using the interspeciflc hybridization between M tabacum and N. aflicana. The frequency of surviving seedling per seed capsule of interspecific hybridization was 4.15. Among them, the frequencies of maternal haploid and hybrid were 1.20 and 2.95, respectively. The chromosome numbers of n=24 for maternal haploid and 2n=47 for hybrid were identified in surviving seedling from interspecific hybridiztion. Except the chromosome number, distinguishable morphological differences of material haploid from hybrid were observed at seedling stage.

• Journal of Plant Biology
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• v.15 no.1
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• pp.28-32
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• 1972

Young haploid leaf derived from the anthers of tobacco plant was cultuerd and plantlets of various ploidies were obtained. When the leaf was put on the medium supplemented with kinetin as growth regulator, plantlets developed directly from the leaf, and the plants coming out in early stage of culture were all haploid. Plants developing in later stage were mostly haploids with some exception of diploid and aneuploid. Leaves were also cultured on the callus-inducing media supplemented with 2,4-D and kinetiion, and the calluses were sub-cultured for six months. Plants developed from these calluses were mostly aneuploids of various chromosome numbers. In view of the fact that the plants directly developed from the leaf were all haploid, the tissue of the original leaf explant was assumed to be uniform as far as chromosome number was concerned. On the other hand, it seemed that the occurrence of various ploidies in the plants derived from the calluses of same origin was the result of the influence of in vitro culture. Apical meristem tissues and various multicellular bodies were formed in the epidermal and inner mesophyll tissues as well as in the sub-epidermal cells.

• Environmental Analysis Health and Toxicology
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• v.15 no.4
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• pp.157-163
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• 2000

2- [(4- Cyanophenyl)amino] -3-chloro-1, 4- naphthalenedione (NQ-Y15) was asssayed for its genotoxic potential by using Salmonella typhimurium reversion assay and in vitro chromosome aberration test on Chinese hamster lung cells. In the Ames test, NQ-Y15 induced his + revertants of Salmonella typhimurium TA 98 and TA1537, reaching levels twice the negative control values. But, NQ-Y15 induced only his+ revertants of Salmonella typhimurium TA1537 more than twice the control values under the condition with metabolic activation system. In the cytogenetic test on chinese hamster lung cells. NQ -Y15 showed significant chromosomal aberrations, but the incidence was significantly reduced in the presence of metabolic activation.

• Clinical and Experimental Reproductive Medicine
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• v.23 no.3
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• pp.367-377
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• 1996

Genes on the long arm of Y chromosome, particularly interval 6, are believed to playa critical role in human spermatogenesis. The objective of this study was to validate a sequenced-tagged site(STS)-mapping strategy for the detection of Yq microdeletion and to use this method to determine the proportion of men with Yq microdeletions in idiopathic, obstructive, nonobstructive azoospermia, severe OATS and in normal males. We analyzed three STS markers mapped to interval 6 within long arm of the Y chromosome from 106 nonobstructive, 30 obstructive azoospermia, 15 severe OATS patients, and normal 42 males in Korean men. By PCR, we tested leukocyte DNA, for the presences of STS markers(DAZ, sY129 and sY134) and SRY gene as internal control. And PCR results were confirmed by Southern hybridization, and were investigated by SSCP analysis for DAZ gene mutation. None of 42 normal males and 30 obstructive azoospermia had microdeletions, Of the 15 severe OATS typed with DAZ, sY129 and sY134, 3(20.0%) patients failed to amplify 1 or more STS markers, and of the 106 nonobstructive azoospermia typed with DAZ, sY129 and sY134, 12(11.3%) patients failed to amplify 1 or more STS markers. From these results, high prevalence(12.4%) of Yq deletion(DAZ, sY129, sY134) in men with nonobstructive idopathic azoospermia and severe OATS were observed in Korean infertility patients. To avoid the infertile offspring by assisted reproductive technique using ICSI or ROSI, genetic diagnosis will be needed in IVF-ET program.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.6
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• pp.682-685
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• 2002

Cytogenetic analysis was conducted to obtaining informations for genetic improvement of spotty belly greenling (Hexagrmmos agrammus) and greenling (H. otakii) in aquaculture. Erythrocytes of spotty belly greenling were slightly larger than those of greenling (p<0.05). The nuclear volume of spotty belly greening erythrocytes averaged 15.14 $\pm$ 0.92 ${\mu}m^3$ while that of greening averaged 14.61 $\pm$ 0.15 $\mu$m^3 the difference was not significant (p>0.05). Consequently, genome size of spotty belly greenling was also slightly larger than those of greenling. DNA content per cell of spotty belly greenling and greenling were 2.15 pg and 2.10 pg, respectively. The modal chromosome number of both greenling species were same as 2n=48 and karyotypes were also identical as 2 metacentrics, 11 snbrnetacentrics and 11 acrocentric pairs $(W: 74), There was no evidence of polymorphism including aneuploidy or sex-related heterornorphisrn for all specimens examined. The nuclear organizer regions (NOR_s)$ were localized on a small acrocentric chromosome pair in both species, Spotty belly greenling showed large sizes of active rRNA coding regions in their chromosomes. However, greenling examined only small sizes of active rRNA coding regions with dimorphism.

• Tuberculosis and Respiratory Diseases
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• v.55 no.6
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• pp.597-611
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• 2003

Background : Loss of the short arm of chromosome 16 is a frequent event in various cancers, which suggests the presence of tumor suppressor gene(s) there. To map precise tumor suppressor loci on the chromosome arm for further positional cloning efforts, we tested 23 primary small cell lung cancers. Method : The DNAs extracted from paraffin embedded tissue blocks with primary tumor and corresponding control tissue were investigated. Twenty polymorphic microsatellite markers located in the short arm of chromosome 16 were used in the microsatellite analysis. Results : We found that six (26.1%) of 23 tumors exhibited LOH in at least one of tested microsatellite markers. Two (8.7%) of 6 tumors exhibiting LOH lost a larger area in chromosome 16p. LOH was observed in five common deleted regions at 16p. Among those areas, LOH between D16S668 and D16S749 was most frequent (21.1%). LOH was also observed at four other regions, between D16S3024 and D16S748, D16S405, D16S420, and D16S753. Six of 23 tumors exhibited shifted bands in at least one of the tested microsatellite markers. Shifted bands occurred in 3.3% (15 of 460) of the loci tested. Conclusion : Our data demonstrated that at least five tumor suppressor loci might exist in the short arm of chromosome 16 and that they may play an important role in small cell lung cancer tumorigenesis.

• Korean Journal of Ichthyology
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• v.5 no.1
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• pp.113-121
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• 1993

Cytogenetic studies and hybridization experiment using two populations of Oryzias latipes from Korea were conducted in order to examine their systematic positions. In the chromosome number of specimens examined. O. sinensis had 46 with a pair of large metacentrics and O. latipes had 48 chromosomes without a pair of large metacentrics. However, the diploid chromosome number of the hybrid between O. latipes and O. sinensis was 47 and they had a large metarcentric chromosome in their karyotype. In the $F_2$ hybrids, distribution of chromosome number was variable among individuals. Hatching rates showed little difference between control and hybrids. However, hatchiabilties of $F_2$ hybrids were decreased by 83.3% as compared with $F_1$ offspring. Incidence of abnormal larvae was increased by 15.3% as compared with their parents. These results indicate that the two karyotype populations formerly regarded as two subspecies would be two distinct allopatric sibling species O. sinensis, and O. latipes.

• Korean Journal of Plant Tissue Culture
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• v.25 no.6
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• pp.453-475
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• 1998

During the 100 years since the initial discovery of meiotic phenomenon many brilliant aspects have been elucidated, but further researches based on light microscopy alone as an experimental tool have been found to have some limits and shortcomings. By the use of electron microscopy and armed with the advanced knowledges on modern genetics and biochemistry it has been possible to applu molecular technology in gaining information on the detailed aspects of meiosis. As synapsis takes place, a three-layered proteinous structure called the synatonemal complex starts to form in the space between the homologous chromosomes. To be more precise, it begins to form along the paired chromosomes early in the prophase I of meiotic division. The mechanism that leads to precise point-by-point pairing between homologous chromocomes division. The mechamism that leads to precise point-by-point pairing between homologous chromosomes remains to be ascertained. Several items of information, however, suggest that chromsome alignment leading to synapsis may be mediated somehow by the nuclear membrane. Pachytene bivalents in eukaryotes are firmly attached to the inner niclear membrane at both termini. This attached begins with unpaired leptotene chromosomes that already have developed a lateral element. Once attached, the loptotene chromosomes begin to synapse. A number of different models have been proposed to account for genetic recombination via exchange between DNA strands following their breakage and subsequent reunion in new arrangement. One of the models accounting for molecular recombination leading to chromatid exchange and chiasma formation was first proposed in 1964 by Holliday, and 30 years later still a modified version of his model is favored. Nicks are made by endomuclease at corresponding sites on one strant of each DNA duplex in nonsister chromatid of a bivalent during prophase 1 of meiosis. The nicked strands loop-out and two strands reassociate into an exchanged arrangement, which is sealed by ligase. The remaining intact strand of each duplex is nicked at a site opposite the cross-over, and the exposed ends are digested by exonuclease action. Considerable progress has been made in recent years in the effort to define the molecular and organization features of the centromere region in the yeast chromosome. Centromere core region of the DNA duplex is flanked by 15 densely packed nucleosomes on ons side and by 3 packed nucleosomes on the other side, that is, 2000 bp on one side and 400 400 bp in the other side. All the telomeres of a given species share a common DNA sequence. Two ends of each chromosome are virtually identical. At the end of each chromosome there exist two kinds of DNA sequence" simple telpmeric sequences and telpmere-associated sequencies. Various studies of telomere replication, function, and behabior are now in progress, all greatly aided by molecular methods. During nuclear division in mitosis as well as in meiosis, the nucleili disappear by the time of metaphase and reappear during nuclear reorganizations in telophase. When telophase begins, small nucleoli form at the NOR of each nucleolar-organizing chromosome, enlarge, and fuse to form one or more large nucleoli. Nucleolus is a special structure attached top a specific nucleolar-organizing region located at a specific site of a particular chromosome. The nucleolus is a vertical factory for the synthesis of rRNAs and the assenbly of ribosome subunit precursors.sors.