• Molecules and Cells
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• 제23권2호
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• pp.220-227
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• 2007

The development of suitable genetic markers would be useful for defining species and delineating the species boundaries of morphologically indistinguishable sponges. In this study, genetic variation in the sequences of nuclear rDNA and the mitochondrial cytochrome c oxidase subunit 1 and 3 (CO1 and CO3) regions were compared in morphologically indistinguishable Korean Halichondriidae sponges in order to determine the most suitable species-specific molecular marker region. The maximal congeneric nucleotide divergences of Halichondriidae sponges in CO1 and CO3 are similar to those found among anthozoan cnidarians, but they are 2- to 8-fold lower than those found among genera of other triploblastic metazoans. Ribosomal internal transcribed spacer regions (ITS: ITS1 + ITS2) showed higher congeneric variation (17.28% in ITS1 and 10.29% in ITS2) than those of CO1 and CO3. Use of the guidelines for species thresholds suggested in the recent literature indicates that the mtDNA regions are not appropriate for use as species-specific DNA markers for the Halichondriidae sponges, whereas the rDNA ITS regions are suitable because ITS exhibits a low level of intraspecific variation and a relatively high level of interspecific variation. In addition, to test the reliability of the ITS regions for identifying Halichondriidae sponges by PCR, a species-specific multiplex PCR primer set was developed.

• The Plant Pathology Journal
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• 제25권4호
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• pp.417-421
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• 2009

The analysis of the full length genome of Korean isolates of Pepper mottle virus (PepMoV) in previous study showed molecular variations and are found to be related to symptom variation and pathogenicity (Kim et al., 2009, Virus Res. 144:83-88). To fully understand the molecular variation of PepMoV in Korea, we further assessed the role of RNA recombination to biological variation and evolution of PepMoV. Full-length genome of a total of 17 Korean-PepMoV and 2 American (CA and FL) isolates were examined for possible detection of genetic recombination using different recombination detections programs and detected 5 and 8 tentative recombination events using RDP3 and Splits Tree4 programs, respectively. Interestingly, tentative recombinants detected such as isolates 57, 134 and 217 were previously identified as severe isolates and 205135 and 205136 as differentiating isolates (Kim et al., 2009, Virus Res. 144:83-88). In addition, recombination was frequently detected in the Vb isolate, the first PepMoV isolate reported in Korea, suggesting significant involvement in the evolution of PepMoV in Korea. These initial results of our recombination analyses among PepMoV isolates in Korea may serve as clues to further investigate the biological variations and evolution of PepMoV brought about by recombination.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 1998년도 Proceedings of International symposium on Recent Technology of Chemical Control of Plant Diseases
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• pp.168-169
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• 1998

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2011년도 추계학술논문요약집
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• pp.548-551
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• 2011

• Bulletin of the Korean Chemical Society
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• 제32권7호
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• pp.2237-2242
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• 2011

Anomalous scaling behaviors such as significantly large growth exponent (${\beta}$) and small reciprocal of dynamic exponent (1/z) values for many molecular crystalline thin films have been reported. In this study, the variation of scaling exponent values and consequent growth behaviors of molecular thin films were more quantitatively analysed using a (1+1)-dimensional surface lateral diffusion model. From these simulations, influence of step edge barriers and grain boundaries of molecular thin films on the various scaling exponent values were elucidated. The simulation results for the scaling exponents were also well consistent with the experimental data for previously reported molecular thin film systems.

• 천문학회보
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• 제46권2호
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• pp.37.2-37.2
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• 2021

Turbulence produces the density and velocity fluctuations in molecular clouds, and dense regions within the density fluctuation are the birthplace of stars. Also, turbulence can produce non-thermal pressure against gravity. Thus, turbulence plays a crucial roles in controlling star formation. However, despite many years of study, the detailed relation between turbulence and star formation remain poorly understood. As part of the Taeduk Radio Astronomy Observatory (TRAO) Key Science Program (KSP), "mapping Turbulent properties In star-forming MolEcular clouds down to the Sonic scale (TIMES; PI: Jeong-Eun Lee)", we mapped two star-forming molecular clouds, the Orion A and the ρ Ophiuchus molecular clouds, in six molecular lines (¹³CO 1-0/C¹⁸O 1-0, HCN 1-0/HCO⁺ 1-0, and CS 2-1/N₂H⁺ 1-0) using the TRAO 14-m telescope. We applied the Principal Component Analysis (PCA) to the observed data in two different ways. The first method is analyzing the variation of line intensities in velocity space to evaluate the velocity power spectrum of underlying turbulence. We investigated the relation between the star formation activities and properties of turbulence. The other method is analyzing the variation of the integrated intensities between the molecular lines to find the characteristic correlation between them. We found that the HCN, HCO⁺, and CS lines well correlate with each other in the integral shaped filament in the Orion A cloud, while the HCO⁺ line is anti-correlate with the HCN and CS lines in L1688 of the Ophiuchus cloud.

• Journal of Microbiology and Biotechnology
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• 제18권1호
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• pp.28-34
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• 2008

Biofilm formation in association with the intercellular adhesion (icaADBC) gene cluster is a serious problem in nosocomial infections of Staphylococcus aureus. In all 112 S. aureus strains tested, the ica genes were present, and none of these strains formed biofilms. The biofilm formation is known to be changeable by environmental factors. We have found about 30% of phase variation in these strains with treatment of tetracycline, pristinamycin, and natrium chloride. However, this phenotype disappeared without these substances. Therefore, we have constructed stable biofilm-producing variants through a passage culture method. To explain the mechanism of this variation, nucleotide changes of ica genes were tested in strain S. aureus 483 and the biofilm-producing variants. No differences of DNA sequence in ica genes were found between the strains. Additionally, molecular analysis of three regulatory genes, the accessory gene regulator (agr) and the staphylococcal accessory regulator (sarA), and in addition, alternative transcription factor ${\sigma}^B$ (sigB), was performed. The data of Northern blot and complementation showed that SigB plays an important role for this biofilm variation in S. aureus 483 and the biofilm-producing variants. Sequence analysis of the sigB operon indicated three point mutations in the rsbU gene, especially in the stop codon, and two point mutations in the rsbW gene. This study shows that this variation of biofilm formation in S. aureus is deduced by the role of sigB, not agr and sarA.

• 한국응용곤충학회지
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• 제54권4호
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• pp.303-310
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• 2015

배추좀나방(Plutella xylostella)은 시설재배지를 중심으로 국내 자연 상태에서 월동한다. 안동지역에서 이른 봄부터 배추좀나방 성페로몬트랩을 이용하여 배추좀나방의 성충 발생 시기를 주기적으로 조사한 결과 연중 4 회의 성충 발생 피크를 보였다. 월동 집단을 대상으로 서로 다른 지역 집단 간 생물적 특성을 조사한 결과 내한성, 약제감수성 및 발육속도에서 뚜렷한 집단 특성을 나타냈다. 분자마커로 집단변이를 분석한 결과 월동세대의 높은 집단변이는 계절이 진행됨에 따라 낮아지는 양상을 나타냈다. 이 결과는 배추좀나방의 국내 월동 집단 사이의 생물적 특성 차이를 나타냈고, 이들의 높은 유전적 분화는 계절이 진행됨에 따라 감소하여 이들 집단 사이의 개체들의 이동에 따른 유전적 교환이 이뤄졌다는 것을 제시했다.

• Journal of Ecology and Environment
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• 제48권1호
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• pp.32-48
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• 2024

Background: Longitudinal connectivity in river systems strongly affects biological components related to ecosystem functioning, thereby playing an important role in shaping local biodiversity and ecosystem health. Environmental DNA (eDNA)-based metabarcoding has an advantage of enabling to sensitively diagnose the presence/absence of species, becoming an efficient/effective approach for studying the community structure of ecosystems. However, little attention has been paid to eDNA-based biomonitoring for river systems, particularly for assessing the river longitudinal connectivity. In this study, by using eDNA we analyzed and compared species diversity and composition among artificial barriers to assess the longitudinal connectivity of the fish community along down-, mid- and upstream in the Hotancheon from the Geum River basin. Moreover, we investigated temporal variation in eDNA fish community structure and species diversity according to season. Results: The results of species detected between eDNA and conventional surveys revealed higher sensitivity for eDNA and 61% of species (23/38) detected in both methods. The results showed that eDNA-based fish community structure differs from down-, mid- and upstream, and species diversity decreased from down to upstream regardless of season. We found that there was generally higher species diversity at the study sites in spring (a total number of species across the sites [n] = 29) than in autumn (n = 27). Nonmetric multidimensional scaling and heatmap analyses further suggest that there was a tendency for community clusters to form in the down-, mid- and upstream, and seasonal variation in the community structure also existed for the sites. Dominant species in the Hotancheon was Rhynchocypris oxycephalus (26.07%) regardless of season, and subdominant species was Nipponocypris koreanus (16.50%) in spring and Odontobutis platycephala (15.73%) in autumn. Artificial barriers appeared to negatively affect the connectivity of some fish species of high mobility. Conclusions: This study attempts to establish a biological monitoring system by highlighting the versatility and power of eDNA metabarcoding in monitoring native fish community and further evaluating the longitudinal connectivity of river ecosystems. The results of this study suggest that eDNA can be applied to identify fish community structure and species diversity in river systems, although some shortcomings remain still need to be resolved.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XIII)
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• pp.634-638
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• 2003

For the investigation of the properties of aqueous fibroin solution, the variation of molecular weight by agregation of silk, morphology and difference of molecular weight at pI value was investigated. The distribution of molecular weight investigated using gel filtration chromatography and formation of aggregates were confirmed by using Field emission scanning electron microscope. The precipitation of fibroin solution at its pI value was compared by molecular weight distribution and the formation of fibroin aggregated were investigated. The aggregation kinetics were investigated at various condition.