• ALGAE
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• 제25권2호
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• pp.65-70
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• 2010

The genus Chaetoceros provides highly diversified diatoms in marine systems. Morphological descriptions of the genus are well-documented, yet the DNA taxonomy of Chaetoceros has not been satisfactorily established. Here, the molecular divergences of the 18S-28S rDNA of Chaetoceros were assessed. DNA similarities were relatively low in both 18S (93.1 $\pm$ 3.9%) and 28S rDNA (81.0 $\pm$ 4.6%). Phylogenies of the 18S, 28S rDNAs showed that Chaetoceros was divided according to individual species, clustering the same species into single clades. Statistical analysis with corrected genetic (p-) distance scores showed that nucleotide divergence of Chaetoceros 28S rDNA significantly differed from that of 18S rDNA (Student's t-test, p < 0.05). This finding suggests that the 28S rDNA may be treated as a more suitable marker for species-level taxonomic distinctions of Chaetoceros.

• Animal cells and systems
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• 제6권2호
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• pp.145-151
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• 2002

Phylogenetic signal present in the mitochondrial 16S ribosomal RNA gene (16S rDNA) and the nuclear large subunit ribosomal RNA gene (28S rDNA) was explored to assess their utility in resolving family level relationships of the superfamily Tephritoidea. These two genes were chosen because they appear to evolve at different rates, and might contribute to resolve both shallow and deeper phylogenetic branches within a highly diversified group. For the 16S rDNA data set, the number of aligned sites was 1,258 bp, but 1,204 bp were used for analysis after excluding sites of ambiguous alignment. Among these 1,204 sites, 662 sites were variable and 450 sites were informative for parsimony analysis. For the 28S rDNA data set, the number of aligned sites was 1,102 bp, but 1,000 bp were used for analysis after excluding sites of ambiguous alignment. Among these 1000 sites, 235 sites were variable and 95 sites were informative for parsimony analysis. Our analyses suggest that: (1) while 16S rDNA is useful for resolving more recent phylogenetic divergences, 28S rDNA can be used to define much deeper phylogenetic branches; (2) the combined analysis of the 16S and 28S rDNAs enhances the overall resolution without losing phylogenetic signal from either single gene analysis; and (3) additional genes that evolve at intermediate rates between the 16S and 28S rDNAs are needed to further resolve relationships among the tephritoid families.

• ALGAE
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• 제24권3호
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• pp.129-138
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• 2009

DNA-based discrimination of species is a powerful way for morphologically otherwise similar species, like centric diatoms. Here, the author sequenced long-range nuclear ribosomal DNAs, spanning from the 18S to the D5 region of the 28S rDNA, of Stephanodiscus, particularly including a Korean isolate. By comparisons, high DNA similarities were detected from the rDNAs of nine Stephanodiscus (>99.4% in 18S rDNA, >98.0% in 28S rDNA). Their genetic distances, however, were significantly different (Kruskal-Wallis test, p < 0.01) compared to two related genera, namely Cyclotella and Discostella. In addition, genetic distances of 18S rDNAs were significantly different (Student’s t-test, p = 0.000) against those of the 28S rDNAs according to individual genera (Cyclotella, Discostella, and Stephanodiscus). Phylogenetic analyses showed that Stephanodiscus and Discostella showed a sister taxon relationship, and their clade was separated from a cluster of Cyclotella (1.00 PP, 100% BP). This suggests that Stephanodiscus has highly conserved sequences of both 18S and 28S rDNA; however, Stephanodiscus is well-separated from other freshwater centric diatoms, such as Cyclotella and Discostella, at the generic level.

• Parasites, Hosts and Diseases
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• 제45권3호
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• pp.181-190
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• 2007

The phylogenie relationships existing among 14 parasitic Platyhelminthes in the Republic of Korea were investigated via the use of the partial 28S ribosomal DNA (rDNA) D1 region and the partial mitochondrial cytochrome c oxidase subunit 1 (mCOI) DNA sequences. The nucleotide sequences were analyzed by length, G + C %, nucleotide differences and gaps in order to determine the analyzed phylogenie relationships. The phylogenie patterns of the 28S rDNA D1 and mCOI regions were closely related within the same class and order as analyzed by the PAUP 4.0 program, with the exception of a few species. These findings indicate that the 28S rDNA gene sequence is more highly conserved than are the mCOI gene sequences. The 28S rDNA gene may prove useful in studies of the systematics and population genetic structures of parasitic Platyhelminthes.

• Parasites, Hosts and Diseases
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• 제45권4호
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• pp.301-306
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• 2007

We attempted to identify parasite DNA in the biliary stones of humans via PCR and DNA sequencing. Genomic DNA was isolated from each of 15 common bile duct (CBD) stones and 5 gallbladder (GB) stones. The patients who had the CBD stones suffered from cholangitis, and the patients with GB stones showed acute cholecystitis, respectively. The 28S and 18S rDNA genes were amplified successfully from 3 and/or 1 common bile duct stone samples, and then cloned and sequenced. The 28S and 18S rDNA sequences were highly conserved among isolates. Identity of the obtained 28S D1 rDNA with that of Clonorchis sinensis was higher than 97.6%, and identity of the 18S rDNA with that of other Ascarididae was 97.9%. Almost no intra-specific variations were detected in the 28S and 18S rDNA with the exception of a few nucleotide variations, i.e., substitution and deletion. These findings suggest that C. sinensis and Ascaris lumbricoides may be related with the biliary stoneformation and development.

• 한국패류학회지
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• 제13권2호
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• pp.91-96
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• 1997

한국산 논우렁이(CIpangopaludina chinensis malleata)와 큰논우렁이 (C. japomica)는 형태학적으로 유사하여 그 감별이 용이치 않다. 본 연구는 이 두 종을 대상으로 28S rDNA DI유전자를 7종의 제한효소로 처리하여 PCR-RDLP기법으로 그 절편을 비교하였다. 절편 상호간에는 차이점을 관찰할 수 없었으나, 두 종으로부터 분석된 28S rDNA DI 유전자의 염기서열에서는 4 부위에서 종간 차이를 보였다.

• 한국산학기술학회논문지
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• 제18권12호
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• pp.466-472
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• 2017

본 연구의 목적은 곰팡이 28S rDNA 염기서열의 메타분석을 통하여 반추위 곰팡이의 다양성을 조사하는데 있다. 'rumen'과 'ruminal'이 반추위 곰팡이 유래 염기서열들을 회수하기 위한 검색어로 사용되었다. 2016년 9월부로 모든 28S rDNA 염기서열이 보관되어 있는 Ribosomal Database Project(RDP, http://rdp.cme.msu.edu) 데이터베이스에서 반추위 곰팡이 유래 28S rDNA 유전자 염기서열(n=165)을 획득하였다. 총 165개의 염기서열은 분류학상의 '문(phylum)'인 Ascomycota, Neocallimastigomycota 및 Basidiomycota로 분류되었고, 165개의 염기서열 중에서 각각 109개, 48개, 8개의 염기서열을 차지하였다. Ascomycota 염기서열은 식물병원성곰팡이나 마이코톡신을 생성하는 곰팡이를 포함하고 있는 '속(genus)' Pseudonectria, Magnaporthe, Alternaria, Cochliobolus, Cladosporium 및 Davidiella로 분류되었다. 또한, Basidiomycota 염기서열은 식물병원성곰팡이를 포함하고 있는 '속(genus)' Thanatephorus와 Cryptococcus로 분류되었다. 뿐만 아니라, Neocallimastigomycota 염기서열의 경우 섭취된 조사료의 주요 구조탄수화물을 분해하는 '속(genus)' Cyllamyces, Neocallimastix, Anaeromyces, Caecomyces, Orpinomyces, Piromyces로 분류되었다. 본 연구는 처음으로 28S rDNA 염기서열의 메타분석을 통해 반추위 곰팡이 다양성에 대한 정보를 통합적으로 제공하였다. 본 연구의 결과는 향후 반추위 곰팡이 연구에 대한 방향을 제공할 것이고, 새로운 분석도구 개발에 응용될 수 있을 것이다.

• 미생물학회지
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• 제39권1호
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• pp.36-39
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• 2003

본 연구에서는 16S rDNA복합중합효소연쇄반응을 이용하여 중이 삼출액에서 미생물병인원에 대한 특성을 알아보았다. 중이염환자의 중이 삼출액에서의 미생물 병인원은 주로 streptococcus pneumoniae, Haemophilus influenzae와 Moraxella catarrhalis이다. 26명의 환자로부터 39개의 중이염의 삼출액을 얻었고, 중이 삼출액에서 DNA를 추출하였다. PCR은 16S rDNA의 C4 region에서 21 base pair의 common primer와 각각 bacterium specific primers [(i) Haemophilus-specific primer (ii) Moraxella-specific primer and (iii) Streptococcus-specific primer]를 이용하여 수행하였다. 39 개의 중이염의 삼출액 시료 중에서, H. influenzae가 24 개(61.5%) 검출되었고, M. catarrhalis는 10 개(25.6%), S.pneumoniae는 3개 (7.7%)가 검출되었다. 16s rDNA 복합중합효소연쇄 반응 진단 결과,11 개(28%)의 중이삼출액 시료에서 음성을 나타내었다. 중이염의 중복감염은 9개의 중이 삼출액시료에서 관찰되었고, 이들은 모두 H.influenzae 와 M. catarrhalis 에 의한 중복감염이었다. 본 연구에서 저자 등은 165 rDNA 복합중합효소연쇄반응이 병원성 미생물을 빠르게 진단하고, 중이삼출액의 미생물 병인론을 추적할 수 있는 좋은 방법으로 제시하는 바이다.

• Parasites, Hosts and Diseases
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• 제42권3호
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• pp.129-135
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• 2004

We compared the DNA sequences of the genus Metagonimus: M. yokogawai, M. takahashii, and M. miyatai. We obtained 288 D1 ribosomal DNA (rDNA) and mitochondrial cytochrome c oxidase subunit I (mtCOI) fragments from the adult worms by PCR, that were cloned and sequenced. Phylogenetic relationships inferred from the nucleotide sequences of the 28S D1 rDNA and mtCOI gene. M. takahashii and M. yokogawai are placed in the same clade supported by DNA sequence and phylogenie tree analysis in 28S D1 rDNA and mtCOI gene region. The above findings tell us that M. takahashii is closer to M. yokogawai than to M. miyatai genetically. This phylogenetic data also support the nomination of M. miyatai as a separate species.

• Parasites, Hosts and Diseases
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• 제42권2호
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• pp.71-75
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• 2004

To determine the molecular phylogenie location of Plagiorchis muris, 28S D1 ribosomal DNA (rDNA) and mitochondrial cytochrome C oxidase subunit I (mtCOI) were sequenced and compared with other trematodes in the family Plagiorchiidae. The 28S D1 tree of P. muris was found to be closely related to those of P. elegans and other Plagiorchis species. And, the mtCOI tree also showed that P. muris is in a separate clade with genus Glypthelmins. These results support a phylogenie relationship between members of the Plagiorchiidae, as suggested by morphologic features.