• The Korean Journal of Malacology
• /
• v.31 no.2
• /
• pp.159-163
• /
• 2015

We report a new record of Myurella nebulosa (Sowerby, 1825) collected by SCUBA diving from sandy bottom of subtidal zone in Jeju Island in Korea. The specimen of M. nebulosa is distinguished from its congeners by having slightly plump shell, high spire, distinctive subsutural band, deep axial ribs, numerous and shallow spiral ribs, ivory in color. In this report, we provided a brief morphological description and photographs of M. nebulosa. An unrooted phylogenetic tree for mitochondrial cox1 sequences using NJ analysis found Korean M. nebulosa sample was clustered with its conspecific sequences, but clearly separated from M. columellaris that is not easy to distinguishable based on external shell morphology alone.

• Korean Journal of Poultry Science
• /
• v.27 no.2
• /
• pp.91-98
• /
• 2000

Phylogenetic tree constructed from the nucleotide sequences of the S1 gene showed that the 15 Korean strains of infectious bronchitis virus(IBV) examined were classified into 2 genetically distinct groups, except one respiratory strain, RB86, which was clustered with Massachusetts group. All the 5 respiratory strains belonged to Korean group I and the rest 9 nephropathogenic strains belonged to Korean group II according to the analysis, based on S1 gene sequences. Like previous classifications corresponded with the geographic origin, Korean stains were discriminated from geographically distinct reference strains of IBV. The nephropathogenic strains within Korean group IIsharing 96% homology were continuously isolated since 1990, and seemed to be genetically stable. Whereas the respiratory strains within Korean group Ⅰ sharing 88% homology were sporadically isolate since 1986m and seemed to be genetically unstable. Because we found putative accumulated point mutation as well as recombination events in Korean group Ⅰ, we discussed why genetic variations have often occurred in respiratory strains rather than nephropathognic strains.

• ALGAE
• /
• v.24 no.2
• /
• pp.79-83
• /
• 2009

Recently deschbed new species, Cladosiphon umezakii Ajisaka (Ectocarpales,Phaeophyceae) is reported in Korea based on morphology and plastid rbcL sequences. Cladosiphon umezakii occurred on low intertidal to subtidal zone along the south and southeast coasts in Korea. Thalli are gold to dark brown, ercct, cylindrical, irregularly branched,and very mucoid. Unitocular zoidangium is developed at the base uf assimilatory filaments. Assimilatory filaments are very long. Eight specimens of the pecies collected from Korea clustered with those of C. umezakii in Japan in rbcL tree. The pecies showed a sister relationship with C. okamuranus. The occurrence of this warm water species is thought an example of northward migration of marine algae caused by global warming. Because C. umezakii is of the economica! importance of the genus as foods and medidnes, the study on mass culture of the species is necessary in korea.

• Journal of Software Engineering Society
• /
• v.25 no.3
• /
• pp.59-62
• /
• 2012

We propose a novel metric for quantitatively comparing different clustered results generated from software clustering algorithms. A quantitative evaluation of software clustering helps understanding of architectural changes of software. The concept of split, which has been used for analysis of genetic characters in bio-informatics, is applied in the analysis of software architecture.

• Korean Journal of Veterinary Research
• /
• v.59 no.2
• /
• pp.69-74
• /
• 2019

Avian malaria is one of the most important general blood parasites of poultry in Southeast Asia. Plasmodium (P.) juxtanucleare causes avian malaria in wild and domestic fowl. This study aimed to identify and characterize the Plasmodium species infecting in Thai native fowl. Blood samples were collected for microscopic examination, followed by detection of the Plasmodium cox I gene by using PCR. Five of the 10 sampled fowl had the desired 588 base pair amplicons. Sequence analysis of the five amplicons indicated that the nucleotide and amino acid sequences were homologous to each other and were closely related (100% identity) to a P. juxtanucleare strain isolated in Japan (AB250415). Furthermore, the phylogenetic tree of the cox I gene showed that the P. juxtanucleare in this study were grouped together and clustered with the Japan strain. The presence of P. juxtanucleare described in this study is the first report of P. juxtanucleare in the Thai native fowl of Thailand.

• Journal of Species Research
• /
• v.11 no.3
• /
• pp.162-168
• /
• 2022

Compared to marine dinoflagellates, freshwater species are rarely recorded in Korea. In the present study, we isolated a freshwater dinoflagellate, Palatinus, from the Paldang Reservoir, Korea, in December 2021. The overall cell shape was ovoid, and the cell size was 34.3 ㎛ in length (25.8-39.5 ㎛) and 28.4 ㎛ in width (21.5-34 ㎛). An eyespot was usually observed near the sulcal region. The Kofoidian plate formula of the species was determined to be 4', 2a, 7", 6c, 5s, 5''', and 2''''. Apical pore complex was not observed. However, variations in the cingular plate caused by the fusion of 3C and 4C were observed. Analyses of 28S rDNA sequences revealed that the unidentified species is 100% similar to Palatinus apiculatus, and clustered together in the same lineage in the phylogenetic tree (100% bootstrap value). Our findings confirmed that the isolated dinoflagellate is Palatinus apiculatus, which was discovered for the first time in Korean freshwaters.

• Korean Journal of Plant Taxonomy
• /
• v.53 no.1
• /
• pp.47-53
• /
• 2023

We have determined the complete chloroplast genome of Erigeron Canadensis isolated in Korea. The circular chloroplast genome of E. canadensis is 152,767 bp long and has four subregions: 84,317 bp of large single-copy and 18,446 bp of small single-copy regions are separated by 25,004 bp of inverted repeat regions including 133 genes (88 protein-coding genes, eight rRNAs, and 37 tRNAs). The chloroplast genome isolated in Korea differs from the Chinese isolate by 103 single-nucleotide polymorphisms (SNPs) and 47 insertions and deletion (INDEL) regions, suggesting different invasion sources of E. canadensis in Korea and China. A nucleotide diversity analysis revealed that the trend of the nucleotide diversity of E. canadensis followed that of 11 Erigeron chloroplasts, except for three peaks. The phylogenetic tree showed that our E. canadensis chloroplast is clustered with E. canadensis reported from China. Erigeron canadensis can be a good target when attempting to understand genetic diversity of invasive species.

• Journal of Veterinary Clinics
• /
• v.25 no.3
• /
• pp.139-145
• /
• 2008

To investigate the genotypic diversity of the porcine reproductive and respiratory syndrome viruses (PRRSV) in Korea, we examined 92 clinical samples from three provinces by RT-PCR and a nested PCR, and the complete open-reading frame 7 (ORF 7) sequences of 15 samples selected from 72 PCR-positive specimens were analyzed. When we compared nucleotide (amino acid) sequences of 80 isolates from Korea and overseas countries, the sequences of 7 samples belonged to North American (NA)-genotype, and those of 8 samples, to European (EU)-genotype. The nucleotide (amino acid) identities between two genotypes were 63.7% (59.8%) to 65.1% (63.1%). When compared with NA prototype VR-2332, the 7 strains of NA-genotype shared 89.8% (93.6%) to 91.2% (96.0%) identity of nucleotide (amino acid) sequence. The 8 strains of EU-type shared 93.6% (92.3%) to 94.3% (93.8%) identity of nucleotide (amino acid) sequence as compared to EU prototype Lelystad. In phylogenetic tree analysis by neighbor-joining method, all of the 8 EU-type strains were clustered into group 4 distinct from ED-prototype Lelystad (group 1). In NA-genotype, 24 domestic isolates reported previously and the 7 strains of NA-type determined in this study were clustered into group 1, while US prototype VR 2332 was classified into different group (group 2). These results suggest that emergence of EU-genotype and the dual-infection of NA- and EU-genotypes may be prevalent in the pig farms in Korea. The high degree of genetic diversity of field PRRSVs should be taken into consideration for control and preventive measures.

• The Journal of Korean Association of Computer Education
• /
• v.11 no.3
• /
• pp.67-80
• /
• 2008

Various document categorization methods have been studied to provide a user with an effective way of browsing a large scale of documents. They do compares set of documents into groups of semantically similar documents automatically. However, the automatic categorization method suffers from low accuracy. This thesis proposes a semi-automatic document categorization method based on the domains of documents. Each documents is belongs to its initial domain. All the documents in each domain are recursively clustered in a level-wise manner, so that the category tree of the documents can be founded. To find the clusters of documents, the stop-word of each document is removed on the document frequency of a word in the domain. For each cluster, its cluster keywords are extracted based on the common keywords among the documents, and are used as the category of the domain. Recursively, each cluster is regarded as a specified domain and the same procedure is repeated until it is terminated by a user. In each level of clustering, a user can adjust any incorrectly clustered documents to improve the accuracy of the document categorization.

• Journal of Life Science
• /
• v.25 no.2
• /
• pp.243-248
• /
• 2015

Cirsium chanroenicum, Cirsium nipponicum, and Cirsium schantarense plants were collected from Changwon, Ulleungdo, and Dooryoon Mountain, respectively. Cirsium japonicum plants were also collected from various locations in Korea. Genomic DNA was prepared from the collected plants and used for amplification of the 18S rDNA, ITS1, 5.8S rDNA, ITS2, and part of 28S rDNA. The ITS1 and ITS2 sequences of the PCR products and from other Cirsium plants reported previously were aligned and compared. Cirsium chanroenicum, Cirsium nipponicum, and Cirsium setidens formed distinct branches on the neighbor-joining tree. Cirsium japonicum and Cirsium pendulum appeared to be close to one another, but Cirsium pendulum plants were clearly clustered in an independent clade. Cirsium shantarense was clustered with the other Cirsium japonicum plants. The most important characteristic that distinguished these two species was the direction of the flowers. All Cirsium japonicum flowers point upward, but Cirsium shantarense flowers point downward. Other than this feature, these two species are almost indistinguishable morphologically. Cirsium chanroenicum is indistinguishable morphologically from Cirsium setidens, but it still formed a distinct group on the neighbor-joining tree based on ITS sequences, suggesting that this species is worth considering as an independent species. Silymarin production of the collected plants was analyzed and appeared to be quite high, indicating that the ability to synthesize silymarin is common to all Cirsium plants analyzed so far.