• The KIPS Transactions:PartB
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• v.17B no.2
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• pp.149-156
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• 2010

Since the premature convergence phenomenon of genetic algorithms (GAs) degrades the performances of GAs significantly, solving this problem provides a lot of effects to the performances of GAs. In this paper, we propose a selective mutation method in order to improve the performances of GAs by alleviating this phenomenon. In the selective mutation, individuals are additionally mutated at the specific region according to their ranks. From this selective mutation, individuals with low ranks are changed a lot and those with high ranks are changed small in the phenotype. Finally, some good individuals search around them in detail and the other individuals have more chances to search new areas. This results in enhancing the performances of GAs through alleviating of the premature convergence phenomenon. We measured the performances of our method with four typical function optimization problems. It was found from experiments that our proposed method considerably improved the performances of GAs.

• BMB Reports
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• v.51 no.1
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• pp.1-2
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• 2018

Positive selection on a new beneficial mutation generates a characteristic pattern of DNA sequence polymorphism when it reaches an intermediate allele frequency. On genome sequences of African Drosophila melanogaster, we detected such signatures of selection at 37 candidate loci and identified "sweeping haplotypes (SHs)" that are increasing or have increased rapidly in frequency due to hitchhiking. Based on geographic distribution of SH frequencies, we could infer whether selective sweeps occurred starting from de novo beneficial mutants under simple constant selective pressure. Single SHs were identified at more than half of loci. However, at many other loci, we observed multiple independent SHs, implying soft selective sweeps due to a high beneficial mutation rate or parallel evolution across space. Interestingly, SH frequencies were intermediate across multiple populations at about a quarter of the loci despite relatively low migration rates inferred between African populations. This invokes a certain form of frequency-dependent selection such as heterozygote advantage. At one locus, we observed a complex pattern of multiple independent that was compatible with recurrent frequency-dependent positive selection on new variants. In conclusion, genomic patterns of positive selection are very diverse, with equal contributions of hard and soft sweeps and a surprisingly large proportion of frequency-dependent selection in D. melanogaster populations.

• KSBB Journal
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• v.23 no.5
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• pp.392-397
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• 2008

Recently, importance of immunosuppression is increasing as internal organ transplant becomes more prevalent with development of medical technology. Mycophenolic acid (MPA) is a selective inhibitor of guanine synthesis and it therefore has antibacterial, antiviral, antitumor and selective immunosuppressive activities. The objective of this study was to maximize MPA productivity through utilizing the MPA generating strain of Penicillium brevicompactum ATCC 16024, by inducing UV mutation and NTG mutation. The highest MPA obtained was 1.146 g/L, 2.051 g/L, and 1.390 g/L from P. brevicompactum UB-3, UB-9, UC-4 respectively mutants derived from UV treatment. P. brevicompactum NC-3 and NA-9 induced from NTG treatment yielded. 575 g/L, 2.238 g/L of MPA production respectively. Mutants capable of the highest observed production of MPA were P. brevicompactum UB-9 and P. brevicompactum NC-3 obtained using the UV and NTG treatments respectively.

• BMB Reports
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• v.46 no.5
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• pp.270-275
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• 2013

It is essential to analyze rare mutations in many fields of biomedical research. However, the detection of rare mutations is usually failed due to the interference of predominant wild-type DNA surrounded. Herein we describe a sensitive and facile method of detecting rare point mutation on the basis of allele-specific amplification in emulsion PCR. The identification and selective amplification of rare mutation are accomplished in one-pot reaction. The allele-specific primers coupled on magnetic beads allow the exclusive amplification and enrichment of the mutant amplicons. The productive beads bearing mutant amplicons are subsequently stained with the fluorescent dyes. Thus, the rare point mutations with a percentage as low as 0.1%, can be detected by fluorescent analysis. The relative percentages of mutation among different samples can be roughly accessed by counting the fraction of fluorescent positive beads through flow cytometry.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.1
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• pp.31-37
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• 2013

Background: Throughout Indonesia, thyroid cancer is one of the ten commonest malignancies, with papillary thyroid carcinoma (PTC) in our hospital accounting for about 60% of all thyroid nodules. Although fine needle aspiration biopsy (FNAB) is the most reliable diagnostic tool, some nodules are diagnosed as indeterminate and second surgery is common for PTC. The aim of this study was to establish the diagnostic value and feasibility of testing the BRAF T1799A mutation on FNA specimens for improving PTC diagnosis. Materials and Methods: This prospective study enrolled 95 patients with thyroid nodules and future surgery planned. Results of mutational status were compared with surgical pathology diagnosis. Results: Of the 70 cases included in the final analysis, 62.8% were PTC and the prevalence of BRAF mutation was 38.6%. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for BRAF mutation analysis were 36%, 100%, 100% and 48%, respectively. With other data findings, nodules with "onset less than 5 year" and "hard consistency" were proven as diagnostic determinants for BRAF mutation with a probability of 62.5%. This mutation was also a significant risk factor for extra-capsular extension. Conclusions: Molecular analysis of the BRAF T1799A mutation in FNAB specimens has high specificity and positive predictive value for PTC. It could be used in the selective patients with clinical characteristics to facilitate PTC diagnosis and for guidance regarding extent of thyroidectomy.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.32B no.12
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• pp.1680-1686
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• 1995

GAs, effective stochastic search algorithms based on the model of natural evolution and genetics, have been successfully applied to various optimization problems. When population size is not large, GAs often suffer from the phenomenon of premature convergence in which all chromosomes in the population lose the diversity of genes before they find the optimal solution. In this paper, we propose that a new heuristic that maintains the diversity of genes by adding some chromosomes with random mutation and selective mutation into population during evolution. And population size changes dynamically with supplement of new chromosomes. Experimental results for several test functions show that when population size is rather small and the length of chromosome is not long, this method is effective.

• Journal of Veterinary Science
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• v.24 no.4
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• pp.51.1-51.17
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• 2023

Background: To date, various genotypes of infectious bronchitis virus (IBV) have co-circulated and in Korea, GI-15 and GI-19 lineages were prevailing. The spike protein, particularly S1 subunit, is responsible for receptor binding, contains hypervariable regions and is also responsible for the emerging of novel variants. Objective: This study aims to investigate the putative major amino acid substitutions for the variants in GI-19. Methods: The S1 sequence data of IBV isolated from 1986 to 2021 in Korea (n = 188) were analyzed. Sequence alignments were carried out using Multiple alignment using Fast Fourier Transform of Geneious prime. The phylogenetic tree was generated using MEGA-11 (ver. 11.0.10) and Bayesian analysis was performed by BEAST v1.10.4. Selective pressure was analyzed via online server Datamonkey. Highlights and visualization of putative critical amino acid were conducted by using PyMol software (version 2.3). Results: Most (93.5%) belonged to the GI-19 lineage in Korea, and the GI-19 lineage was further divided into seven subgroups: KM91-like (Clade A and B), K40/09-like, QX-like (I-IV). Positive selection was identified at nine and six residues in S1 for KM91-like and QX-like IBVs, respectively. In addition, several positive selection sites of S1-NTD were indicated to have mutations at common locations even when new clades were generated. They were all located on the lateral surface of the quaternary structure of the S1 subunits in close proximity to the receptor-binding motif (RBM), putative RBM motif and neutralizing antigenic sites in S1. Conclusions: Our results suggest RBM surrounding sites in the S1 subunit of IBV are highly susceptible to mutation by selective pressure during evolution.

• Journal of Plant Biology
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• v.36 no.1
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• pp.105-112
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• 1993

Selection of glyphosate-resistant clones from MNNG-treated mesophyll protoplasts of haploid tobacco and their differentiation were studied. The protoplasts were treated with 0.1 to 100 $\mu\textrm{g}$/mL N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) for 30 min when they expanded to oval shapes. After the treatment, the protoplasts in 4-16 cell stages were transferred to the selective medium containing 1 mM glyphosate for the selection of the glyphosate-resistant colonies. The efficiency of the cell division of the protoplasts in the selective medium decreased as the MNNG concentrations in creased. Optimal MNNG concentration for induction of the glyphosate-resistant clones was 10$\mu\textrm{g}$/mL and mutation frequency was 2.66$\times$10-6. The stability of the glypohsate-resistance of the clones was examined by prolonged subculture in the medium with 1 mM glyphosate, and the resistant clones were survived more than 10 months. Among them one clone has been proliferating and greening and the others were proliferating without greening or greening with slower proliferating.

• Korean Journal of Biological Psychiatry
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• v.26 no.2
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• pp.33-38
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• 2019

Psychiatric disorder as dysfunctional behavioural syndrome is a paradoxical phenomenon that is difficult to explain evolutionarily because moderate prevalence rate, high heritability and relatively low fitness are shown. Several evolutionary genetic models have been proposed to address this paradox. In this paper, I explain each model by dividing it into selective neutrality, mutation-selection balance, and balancing selection hypothesis, and discuss the advantages and disadvantages of them. In addition, the feasibility of niche specialization and frequency dependent selection as the plausible explanation about the central paradox is briefly discussed.

• Microbiology and Biotechnology Letters
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• v.19 no.2
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• pp.140-146
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• 1991

Mutation experiments were performed to select the mutant of Aspergillus niger 55, which had lost almost all the ability to produce transglucosidases but retained that of high productivity of raw meal saccharifying enzyme, by means of successive induction with N-methyl-N'-nitro-N-nitrosoguanidine(MNNG), ultraviolet(UV) light, and ${\gamma}$-rays. Also, we used the mutant enrichment techniques, such as liquid culture-filtration procedure and differential heat sensitivity of conidia, in order to increase the possibility of obtaining a mutant. The glucoamylase productivity of mutant PFST-38 was 11 times higher than that of the parent strain. The mutant PFST-38 was morphologically identical to the parent strain, except for the size of conidia, the tendency to form conidia and the lenght of conidiophore. Asp. niger mutant PFST-38 apeared to be useful for the submerged production of the raw corn meal saccharifying enzyme.