• Parasites, Hosts and Diseases
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• v.45 no.3
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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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.466-472
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• 2017

This study was designed to examine the diversity census of fungi in rumen microbiome via meta-analysis of fungal 28S rDNA sequences. Both terms, "rumen" and "ruminal," were searched to retrieve the sequences of rumen fungi. As of September 2016, these sequences (n=165) of ruminal origin were retrieved from the Ribosomal Database Project (RDP; http://rdp.cme.msu.edu), an archive of all 28S rDNA sequences and were assigned to the phyla Ascomycota, Neocallimastigomycota, and Basidiomycota, which accounted for 109, 48, and 8 of the 165 sequences, respectively. Ascomycota sequences were assigned to the genera Pseudonectria, Magnaporthe, Alternaria, Cochliobolus, Cladosporium, and Davidiella, including fungal plant pathogens or mycotoxigenic species. Moreover, Basidiomycota sequences were assigned to the genera Thanatephorus and Cryptococcus, including fungal plant pathogens. Furthermore, Neocallimastigomycota sequences were assigned to the genera Cyllamyces, Neocallimastix, Anaeromyces, Caecomyces, Orpinomyces, and Piromyces, which may degrade the major structural carbohydrates of the ingested plant material. This study provided a collective view of the rumen fungal diversity using a meta-analysis of 28S rDNA sequences. The present results will provide a direction for further studies on ruminal fungi and be applicable to the development of new analytic tools.

• The Plant Pathology Journal
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• v.40 no.2
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• pp.171-191
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• 2024

Identification of Helicotylenchus species is very challenging due to phenotypic plasticity and existence of cryptic species complexes. Recently, the use of rDNA barcodes has proven to be useful for identification of Helicotylenchus. Molecular markers are a quick diagnostic tool and are crucial for discriminating related species and resolving cryptic species complexes within this speciose genus. However, DNA barcoding is not an error-free approach. The public databases appear to be marred by incorrect sequences, arising from sequencing errors, mislabeling, and misidentifications. Herein, we provide a comprehensive analysis of the newly obtained, and published DNA sequences of Helicotylenchus, revealing the potential faults in the available DNA barcodes. A total of 97 sequences (25 nearly full-length 18S-rRNA, 12 partial 28S-rRNA, 16 partial internal transcribed spacer [ITS]-rRNA, and 44 partial cytochrome c oxidase subunit I [COI] gene sequences) were newly obtained in the present study. Phylogenetic relationships between species are given as inferred from the analyses of 103 sequences of 18S-rRNA, 469 sequences of 28S-rRNA, 183 sequences of ITS-rRNA, and 63 sequences of COI. Remarks on suggested corrections of published accessions in GenBank database are given. Additionally, COI gene sequences of H. dihystera, H. asiaticus and the contentious H. microlobus are provided herein for the first time. Similar to rDNA gene analyses, the COI sequences support the genetic distinctness and validity of H. microlobus. DNA barcodes from type material are needed for resolving the taxonomic status of the unresolved taxonomic groups within the genus.

• Mycobiology
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• v.28 no.1
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• pp.11-16
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• 2000

The nucleotide sequences of the internal transcribed spacer (ITS) regions of the ribosomal DNA including the 5.8S ribosomal RNA gene (rDNA) have been determined for 11 species in order to analyze their intrageneric relationships. The total length of these sequences ranged from 530 nucleotides for Trichoderma reesei KCTC 1286 to 553 nucleotide for Trichoderma koningii IAM 12534. Generally speaking, the length of ITS1 region was about 30 nucleotides longer than that of the ITS2 region. Also, the sequences of 5.8S rDNA were more conserved in length and variation than those of ITS regions. Although the variable ITS sequences were often ambiguously aligned, the conserved sites were also found. Thus, a neighbor-joining tree was constructed using the full sequence data of the ITS regions and the 5.8S rDNA. The Trichoderma genus used to be grouped on the basis of the morphological features and especially the shape of phialides needs to be reexamined. The phylogenetic tree displayed the presence of monophylogeny in the species of Trichoderma. Therefore, it was difficult to distinguish the intrageneric relationships in the Trichoderma genus.

• The Korean Journal of Malacology
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• v.13 no.2
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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.

• Mycobiology
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• v.28 no.1
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• pp.17-26
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• 2000

The orchid symbiotic fungi were isolated from the roots of Korean native orchid (Cymbidium goeringii) collected and Chinese orchid (C. sinense) obtained from greenhouses. They were identified as a species of Rhizoctonia, based on the sequences of 18r rDNA, the microscopic observations of mycelia, and the symbiotic relationships with commercial orchids. The isolate collected from Chinese orchids was revealed to be a species of Ceratobasidium endophytica, and to be different from the other isolates at the thickness of the mycelia stained in the root cells of Korean native orchids. The other isolates collected from the Korean native orchids were considered to be a species of Tulsanella repens (anamorphic: Epulorhiza repens) or its related one. The physiologic or microscopic variations were oftenly observed among them, but the tendency of grouping these in the 18s rDNA sequences were observed to be consistent with those of the localities collected. The further taxonomical segregating for Korean symbiotic fungi was not made because the information concerned were limited in this moment, but was recognized as based on the sequences of 18s DNA.

• Journal of Life Science
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• v.22 no.8
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• pp.1120-1125
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• 2012

Cirsium pendulum plants were collected from Hongcheon, Pyeongchang, Wonju, Yangyang in Kangwondo, Gapyeong in Gyeongkido, and Choongju in Choongcheongbukdo. Cirsium setidens plants were collected from Taebaek in Kangwondo and Bonghwa in Kyeongsangbukdo. Genomic DNA was prepared from those plants and used for the amplification of 18S rDNA, ITS1, 5.8S rDNA, ITS2, and part of 28S rDNA. The PCR products were sequenced, and the sequence was deposited in the GenBank. The comparison of those sequences has revealed that the rDNA sequences are identical for all six C. pendulum plants, but that the ITS1 and ITS2 sequences contain variable nucleotides. The two C. setidens plants had different nucleotides in 18S rDNA, ITS1, and ITS2. The comparison of the DNA sequences of C. pendulum and C. setidens collected in this study with C. pendulum of Hokkaido in Japan and C. japonicum of Anhui in China indicated that the plants of those three species are clearly divided into three distinct groups. The silymarin content of the collected plants was analyzed and turned out to be quite high. Therefore, it has been found that both C. pendulum and C. setidens plants are producing large amounts of silymarin, which has been reported to have various medicinal effects.

• ALGAE
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• v.24 no.3
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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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• v.42 no.3
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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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• v.45 no.4
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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.