• The Plant Pathology Journal
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• 제15권4호
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• pp.228-235
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• 1999

Genetic diversity of ninety-five Korean isolates of Phytophthora was investigated on the basis of PCR-RFLP of ribosomal DNA. The isolates were previously identified as following fifteen species by mycological and cultural characteristics; P. boehmeriae, P. cactorum, P. cambivora, P. capsici, P. cinnamoni, P. citricola, P. citrophthora, P. cryptogea, P. drechsleri, P. erythroseptica, P. infestans, P. megasperma, P. nicotianae, P. palmivora and P. sojae. The regions of small subunit (SSU) and internal transcribed spacer (ITS) of rDNA were amplified with primer pair, NS1 and ITS4, by polymerase chain reaction (PCR) and digested with nine restriction enzymes. P. boehmeriae, P. cactorum, P. cambivora, P. capsici, P. cinnamomi, P. citricola, P. citrphthora, P. infestans, P. nicotianae and P. palmivora showed specific band patterns for each species. However, P. sojae and P. erythroseptica presented identical band patterns and P. cryptogea, P. drechsleri and P. megasperma were divided into six groups, which were not compatible with delineation of the species. A group originated from cucurbits showed distinct band patterns from other groups, but the other five groups were closely related within 96.0% similarity, forming one complex group. Consequently, Korean isolates of Phytophthora were divided into thirteen genetic groups and each group was readily differentiated by comparing digestion patterns of AvaII, HaeIII, MboI, HhaI and MspI. Therefore, PCR-RFLP of rDNA using the five enzymes can be used to differentiate or identify the Phytophthora species reported in Korea so far.

• The Korean Journal of Ecology
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• 제24권6호
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• pp.359-364
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• 2001

Regional variations of Dictyostelid cellular slime molds were examined using molecular data. The intertranscribed spacer regions including the 5.8S ribosomal DNA of 2 species(D. purpureum, P. violaceum) of Cellular Slime Molds were sequenced and analyzed. Among 13 strains of D. purpureum and 12 strains of P. violaceum analyzed, each two strains were obtained from ATCC and the others were isolated from the forest soils in Korea. The sequences of the 5.8S ribosomal DNA were conserved among the strains of the same species, but unexpectedly highly variable among species. A high level of genetic diversity was found which was best resolved at the genus/species level as well as the family level by sequence data from the ITS 1 and ITS 2 regions. According to the sequence alignments by CLUSTAL X and the phylogeographic analyses by PAUP, 12 strains of P. violaceum were divided into three groups among which there were no difference of the morphological characteristics. Among 13 strains of D. purpureum, genetic variations were related to two morphological types, the temperate and subtropical type. There was no variation pattern according to geography in Korea, but there were some variations between Korea and other countries.

• 한국균학회지
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• 제32권2호
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• pp.148-151
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• 2004

본 연구는 Phellinus linteus와 관련 담자균류 속간의 IGS I 영역의 분석에 기초한 분류체계를 정립하기 위해서 실시하였다. 실험에 사용된 Phellinus linteus 균주의 IGS I 영역은 730 bp였고 다른 담자균류의 IGS I 영역과 비교시 5' 말단부위의 $1{\sim}280\;base$까지는 각 균주들간의 보존성이 높게 나타났으며 3' 말단부위로 갈수록 보존성이 감소하다가 다시 증가하는 경향을 보였다. 담자균류의 IGS 영역에 대한 연구가 앞으로 진행된다면 ITS 영역의 비교와 더불어 새로운 계통분류지표로 이용될 수 있을 것이다.

• Environmental Engineering Research
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• 제14권1호
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• pp.3-9
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• 2009

Microorganisms play an important role in the geochemical cycles, industry, environmental cleanup, and biotechnology among other fields. Given the high microbial diversity, identification of the microorganism is essential in understanding and managing the processes. One of the most popular and powerful method for microbial identification is comparative 16S rRNA gene analysis. Due to the highly conserved nature of this essential gene, sequencing and later comparison of it against known rRNA databases can provide assignment of the bacteria into the taxonomy, and the identity of its closest relatives. Isolation and sequencing of 16S rRNA genes directly from natural environments (either from DNA or RNA) can also be used to study the structure of the whole microbial community. Nowadays, novel sequencing technologies with massive outputs are giving researchers worldwide the chance to study the microbial world with a depth that was previously too expensive to achieve. In this article we describe commonly used research approaches for the study of individual microorganisms and microbial communities using the tools provided by Ribosomal Database Project website.

• 미생물학회지
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• 제30권6호
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• pp.472-478
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• 1992

HTLV-1 이 pol 유전자산물을 합성하기 위해서는 genome-size mRNA 를 번역해 나아가는 ribosome 이 -1 방향으로 두차례 frame 을 바꾸어야 한다. 우리는 단 한차계의 frameshifting 만으로도 많은 양의 Gag-Pro-Pol polyprotein 의 합성어 가능하도록 gag 와 pro 유전자의 frame 을 연결시킨 mutant RNA 를 제작하였다. 이 돌연변이를 이용하여 ribosome 의 shift site 하류영역내에 형성이 예상되는 RNA 의 이차구조 또는 삼차 구조가 -1 frameshifting 을 결정하는 인자로서 작용하는지의 여부를 조사하였다. 결손변이주의를 해석한 결과 pro-pol 중첩영역에서 효율적으로 frameshifting 이 일어나기 위해서는 stem-loop 가 필수적으로 형성되어야 하지만 pseudoknot 의 형성은 그다지 중요하지 않다는 사실을 알았다.

• 한국버섯학회지
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• 제4권2호
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• pp.43-47
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• 2006

국내에서 재배하여 생산되고 있는 상황버섯의 일종인 PMO-P4균주에 대한 ITS 영역의 염기서열 분석을 실시하였으며 목질 진흙버섯으로 잘 알려져 있는 P. linteus와 함께 RFLP분석을 통하여 상호 비교한 결과 PMO-P4균주는 P. baumii로 판명되었다. 이 결과를 토대로 이미 보고되어 있는 Phellinus속 균주들과의 종간 ITS 영역의 상동성을 비교한 결과 48.6%-72.2%였으며 본 연구에서 비교한 종들 가운데서는 P. linteus와 상동성이 가장 높았으며 P. gilvus와 상동성이 가장 낮았다.

• Journal of Microbiology and Biotechnology
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• 제5권4호
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• pp.194-199
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• 1995

A portion (7.4 kb) of ribosomal DNA tandem repeat unit from a genome of the mushroom T. matsutake has been cloned. A 1.75 kb EcoRI fragment was cloned first using S. cerevisiae 255 rRNA gene as a probe, and this was then used for further cloning. A chromosomal walking experiment was carried out and the upstream region of the 1.75 kb fragment was cloned using SmaI/BamHI enzyme, the size was estimated to be 5.2 kb in length. Part of the downstream region of the 1.75 kb fragment was also cloned using XbaI/BamHI enzymes. Restriction enzyme maps of three cloned DNA fragments were constructed. Northern hybridization, using total RNA of T. matsutake, and the restriction fragments of three cloned DNAs as probes, revealed that all four ribosomal RNA genes (large subunit[LSU], small subunit [SSU], 5.85 and 5S rRNA genes) are present in the cloned region. The gene organization of the rDNA are regarded as an intergenic spacer [IGS]2 (partial) - SSU rRNA - internal transcribed spacer [ITS]1 - 5.8S rRNA - ITS2 - LSU rRNA - IGS1 -5S rRNA - IG52 (partial).

• 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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• 제37권4호
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• pp.215-228
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• 1999

To choose one or more appropriate molecular markers or gene regions for resolving a particular systematic question among the organisms at a certain categorical level is still a very difficult process. The primary goal of this review, therefore, is to provide a theoretical information in choosing one or more molecular markers or gene regions by illustrating general properties and phylogenetic utilities of nuclear ribosomal DNA (rDNA) and mitochondrial DNA (mtDNA) that have been most commonly used for phylogenetic researches. The highly conserved molecular markers and/or gene regions are useful for investigating phylogenetic relationships at higher categorical levels (deep branches of evolutionary history). On the other hand, the hypervariable molecular markers and/or gene regions are useful for elucidating phylogenetic relationships at lower categorical levels (recently diverged branches). In summary, different selective forces have led to the evolution of various molecular markers or gene regions with varying degrees of sequence conservation. Thus, appropriate molecular markers or gene regions should be chosen with even greater caution to deduce true phylogenetic relationships over a broad taxonomic spectrum.

• Parasites, Hosts and Diseases
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• 제41권2호
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• pp.89-96
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• 2003

Among the panel of monoclonal antibodies (mAb) against Toxoplasma gondii, mAb of Tg621 (Tg621) clone blotted 38 kDa protein which localized in the cytoplasm of tachyzoites by immunofluorescence microscopy The protein was not released into the parasitophorous vacuole during or after invasion. The cDNA fragment encoding the protein was obtained by screening a T. gondii cDNA expression library with Tg621. The full length cDNA sequence was completed with 5’-RACE as 1,592 bp, which contained open reading frame of 942 bp. The deduced amino acid sequence of Tg621 consisted of a polypeptide of 313 amino acids, with significant homology to ribosomal P proteins (RPP) of other organisms especially high to those of apicomplexan species. The expressed and purified TgRPP was assayed in western blot with the sera of toxoplasmosis patients and normal sera, which resulted in the 74.0% of positive reactions in toxoplasmosis patients whereas 8.3% in normal group. Therefore, the antibody formation against TgRPP in toxoplasmosis patients was regarded as specific for T. gondii infection and suggested a potential autoantibody.