• Korean Journal of Environmental Biology
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• v.41 no.4
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• pp.657-665
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• 2023

The root-lesion nematode Pratylenchus spp. is the most important plantparasitic nematode due to its worldwide distribution, wide host ranges, and migratory endoparasitic characteristics. One population of Pratylenchus collected from the giant pussy willow (Salix chaenomeloides Kimura) in the Andong area as part of a nematode survey in Korea was characterized morphologically and by molecular methods. The analysis of morphological measurements and morphometric characteristics, as well as DNA sequencing of the rRNA large subunit (LSU) D2/D3 expansion segments and the internal transcribed spacer (ITS) gene sequence, confirmed the identity of this population as P. hippeastri. This study is the first report of P. hippeastri associated with Salix chaenomeloides in Korea and worldwide. Further studies on distribution and pathogenicity in different P. hippeastri host crops, such as grapevines, strawberries, and apples, are necessary. The taxonomic keys to 16 Pratylenchus species in Korea are provided.

• The Korean Journal of Mycology
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• v.52 no.2
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• pp.97-108
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• 2024

In this study, three fungal isolates belonging to the phylum Ascomycota under classes Leotiomycetes, Eurotiomycetes, and Sordariomycetes were isolated from soil in Korea. These species were designated as KNUF-22-003, KNUF-22-005, and KNUF-20-NI016, respectively, and identified based on their phylogenetic relationships and morphological characteristics. The isolates were confirmed through molecular phylogenetic analyses of their internal transcribed spacer (ITS) region, 28S rDNA large subunit (LSU), and actin (ACT1 ) gene sequences. Cultural and morphological characteristics of strains KNUF-22-003, KNUF-22-005, and KNUF-20-NI016 were matched with Chaetomella oblonga CBS110.78^T, Oidiodendron chlamydosporicum CBS403.69^T, and Sarocladium subulatum CBS217.35^T, respectively. To the best of our knowledge, this is the first report on C. oblonga, O. chlamydosporicum, and S. subulatum in Korea.

• Journal of Microbiology and Biotechnology
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• v.23 no.7
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• pp.905-912
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• 2013

A novel species, Metschnikowia cibodasensis, is proposed to accommodate eight strains (ID03-$0093^T$, ID03-0094, ID03-0095, ID03-0096, ID03-0097, ID03-0098, ID03-0099, and ID03-0109) isolated from flowers of Saurauia pendula, Berberis nepalensis, and Brunfelsia americana in Cibodas Botanical Garden, West Java, Indonesia. The type strain of M. cibodasensis is ID03-$0093^T$ (= NBRC $101693^T$ =UICC $Y-335^T$ = BTCC-$Y25^T$). The common features of M. cibodasensis are a spherical to ellipsoidopedunculate shaped ascus, which contains one or two needle-shaped ascospores, and lyse at maturity. Asci generally develop directly from vegetative cells but sometimes from chlamydospores. The neighbor-joining tree based on the D1/D2 domain of nuclear large subunit (nLSU) ribosomal DNA sequences strongly supports that M. cibodasensis (eight strains) and its closest teleomorphic species, M. reukaufii, are different species by a 100% bootstrap value. The type strain of M. cibodasensis, ID03-$0093^T$, differed from M. reukaufii NBRC $1679^T$ by six nt (five substitutions and one deletion) in their D1/D2 region of nLSU rDNA, and by 18 nt (five deletions, four insertions, and nine substitutions) in their internal transcribed spacer regions of rDNA, respectively. Four strains representative of M. cibodasensis (ID03-$0093^T$, ID03-0095, ID03-0096, and ID03-0099) showed a mol% G+C content of $44.05{\pm}0.25%$, whereas that of M. reukaufii NBRC $1679^T$ was 41.3%. The low value of DNA-DNA homology (5-16%) in four strains of M. cibodasensis and M. reukaufii NBRC $1679^T$ strongly supported that these strains represent a distinct species.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.5
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• pp.631-639
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• 2016

China has a long history of sheep (Ovis aries [O. aries]) breeding and an abundance of sheep genetic resources. Knowledge of the complete O. aries mitogenome should facilitate the study of the evolutionary history of the species. Therefore, the complete mitogenome of O. aries was sequenced and annotated. In order to characterize the mitogenomes of 3 Chinese sheep breeds (Altay sheep [AL], Shandong large-tailed sheep [SD], and small-tailed Hulun Buir sheep [sHL]), 19 sets of primers were employed to amplify contiguous, overlapping segments of the complete mitochondrial DNA (mtDNA) sequence of each breed. The sizes of the complete mitochondrial genomes of the sHL, AL, and SD breeds were 16,617 bp, 16,613 bp, and 16,613 bp, respectively. The mitochondrial genomes were deposited in the GenBank database with accession numbers KP702285 (AL sheep), KP981378 (SD sheep), and KP981380 (sHL sheep) respectively. The organization of the 3 analyzed sheep mitochondrial genomes was similar, with each consisting of 22 tRNA genes, 2 rRNA genes (12S rRNA and 16S rRNA), 13 protein-coding genes, and 1 control region (D-loop). The NADH dehydrogenase subunit 6 (ND6) and 8 tRNA genes were encoded on the light strand, whereas the rest of the mitochondrial genes were encoded on the heavy strand. The nucleotide skewness of the coding strands of the 3 analyzed mitogenomes was biased toward A and T. We constructed a phylogenetic tree using the complete mitogenomes of each type of sheep to allow us to understand the genetic relationships between Chinese breeds of O. aries and those developed and utilized in other countries. Our findings provide important information regarding the O. aries mitogenome and the evolutionary history of O. aries inside and outside China. In addition, our results provide a foundation for further exploration of the taxonomic status of O. aries.

• Korean Journal of Environmental Biology
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• v.37 no.2
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• pp.119-128
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• 2019

The morphological characteristics of the bloom-forming dinoflagellate Akashiwo sanguinea isolated from Jangmok Harbour, Geoje in Korea was examined using light and scanning electron microscope (SEM), and its large subunit (LSU) rDNA was sequenced. Additionally, investigation was done on the effects of temperature and salinity on the growth of A. sanguinea. The cells were dorso-ventrally compressed up to 54.7-70.3 ㎛ long and 31.5-48.5 ㎛ wide. The epicone was conical while the hypocone was separated into two lobes. The nucleus was positioned at the center of the cell. The yellow-brown chloroplasts radiated close to the cell center. SEM observation indicated that A. sanguinea has an e-shaped apical groove. Molecular phylogeny based on LSU rDNA gene sequences revealed that the A. sanguinea strains isolated from Jangmok Harbor were classified in the clade of ribotype A. The maximum growth rate (0.50 day^-1) was observed at 20℃ and 20 psu, while the maximum cell density (1,372 cells mL^-1) was observed at 25℃ and 30 psu. This indicates that the blooms of A. sanguinea ribotype A in Korean coastal area are affected by water temperature, rather than the salinity.

• Korean Journal of Environmental Biology
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• v.37 no.1
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• pp.31-41
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• 2019

The toxic dinoflagellate Gymnodinium catenatum isolated from the southern coast of Korea was described under light and scanning electron microscopy, and its large subunit (LSU) rDNA was sequenced. In addition, the effects of temperature and salinity on its growth were investigated. The cells of G. catenatum, as viewed under the electronic microscope, were green-brown color, $38.1-77.4{\mu}m$ in length and $26.1-40.8{\mu}m$ in width. The epicone was conical, while the hypocone was trapezoidal. The nucleus was located at the central part of the cell. The apical groove was horseshoe-shaped and small pores were irregularly distributed on the cell surface. Molecular phylogeny based on LSU rDNA gene sequences showed that the Korean G. catenatum and previously reported species formed a monophyletic clade within Gymnodinium sensu stricto clade. The maximum growth rate of $0.37day^{-1}$, was obtained at $25^{\circ}C$ and 35 psu, and the maximum cell density of $1,073cells\;mL^{-1}$, was observed at $20^{\circ}C$ and 25 psu. However, G. catenatum did not grow at temperature < $15^{\circ}C$ and < $30^{\circ}C$. These results suggest that environmental conditions of summer and autumn in the southern coast of Korea may be favorable for the growth of G. catenatum.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.35-35
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• 2003

We, for the first time, reported molecular sequences of large subunit ribosomal DNA Dl-D3 region of A. hiranoi, A. leei and A. satoanum hitherto unreported. In addition, this study presented the full-length sequences of A. affine, A. fraterculus, A. catenella and A. tamarense occurring in Korean coastal waters. In total, 17 Alexandrium morphospecies were subjected to the phylogenetic analysis using the Maximum-likelihood (ML) method. The alignment result of sequences of A. hiranoi and A. pseudogonyaulax showed that there were only two substitutions without length heterogeneity implying their genetic affiliation. In ML tree, A. leei formed a deeply diverging branch probably because of the accelerated evolutionary rate, and its phylogenetic position was so ambiguous to resolve the phylogenetic relationship to the residual taxa. An A. satoanum culture showing morphological variation in the sulcal plate formed an independent divergent branch with consistent sister relationship to A. hiranoi/A. pseudogonyaulax clade supported by the high posterior probability (PP) value. Blast search in GenBank showed the sequence data of A. affine, A. fraterculus, A. catenella and A. tamarense corresponded to their morphological species designation. In ML tree, Alexandrium species were commonly split into four main clades. The inter-clade relationships were not clear and usually supported by the week PP values. In general, the sulcal plate of Alexandrium species seemed to reflect the true phylogeny at the main clade level, and the connection between the 1 and the apical pore complex seemed to reflect the phylogeny at the subclade level.

• Journal of Microbiology and Biotechnology
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• v.15 no.5
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• pp.1028-1038
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• 2005

To elucidate phylogenetic relationships of Phellinus and its related genera, nuclear internal transcribed spacer and mitochondrial small subunit ribosomal DNA sequences from 65 strains were determined and compared. The combined dataset of two sequences increased informative characters and led to the production of trees with higher levels of resolution. Phylogenetic analysis of the combined dataset revealed thirteen evolutionary lineages and several unresolved species that were together subdivided into two large clusters consisting of oligonucleate species and binucleate species. These results coincided with previous cytological, morphological, and molecular studies. It is newly recognized that the Phellinus linteus complex forms a sister clade to Inonotus, and that Fulvifomes is somehow related to Inocutis. The Phellinus linteus complex of dimitic perennial taxa made an independent clade from Inonotus and suggested that hyphal miticity and fruitbody permanence had enough phylogenetic significance to keep the complex within the traditional genus Phellinus. Taxa lacking setae were clustered into Fulvifomes, Phylloporia, Inocutis, and Fomitiporia, and the first three were closely related sister groups, but Fomitiporia was a genus distantly related to them. Several taxa with branched setae were shown among distantly related genera. Molecular evidence indicated that the ancestral nuclear type could be a binucleate feature, and that there might be parallel gains of branched setae and parallel losses of setae in the Hymenochaetales.

• The Korean Journal of Mycology
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• v.49 no.4
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• pp.539-545
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• 2021

A cercosporoid fungus associated with angular leaf spots on the leaves of common fig (Ficus carica) in Korea is known to be morphologically similar to Passalora, but phylogenetically similar to Pseudocercospora. To clarify the ambiguity, six fig samples with angular leaf spots were collected and examined using a microscope, and two representative isolates were sequenced for multiple genes. The morphological characteristics were consistent with previous descriptions of Passalora bolleana. Molecular phylogenetic analysis based on the internal transcribed spacer and large subunit ribosomal DNA (rDNA) regions showed that the Korean isolates, as well as previously published Korean and Romanian isolates, formed a well-supported group in the clade of Pseudocercospora species. Consequently, the current Korean isolates should be correctly described as Pseudocercospora bolleana. Additionally, Pseudocercospora fici-caricae, a cercosporoid fungus previously described as a leaf pathogen on common fig in Taiwan and Korea, was also compared and discussed.

• Korean Journal of Plant Tissue Culture
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• v.25 no.6
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• pp.453-475
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• 1998

During the 100 years since the initial discovery of meiotic phenomenon many brilliant aspects have been elucidated, but further researches based on light microscopy alone as an experimental tool have been found to have some limits and shortcomings. By the use of electron microscopy and armed with the advanced knowledges on modern genetics and biochemistry it has been possible to applu molecular technology in gaining information on the detailed aspects of meiosis. As synapsis takes place, a three-layered proteinous structure called the synatonemal complex starts to form in the space between the homologous chromosomes. To be more precise, it begins to form along the paired chromosomes early in the prophase I of meiotic division. The mechanism that leads to precise point-by-point pairing between homologous chromocomes division. The mechamism that leads to precise point-by-point pairing between homologous chromosomes remains to be ascertained. Several items of information, however, suggest that chromsome alignment leading to synapsis may be mediated somehow by the nuclear membrane. Pachytene bivalents in eukaryotes are firmly attached to the inner niclear membrane at both termini. This attached begins with unpaired leptotene chromosomes that already have developed a lateral element. Once attached, the loptotene chromosomes begin to synapse. A number of different models have been proposed to account for genetic recombination via exchange between DNA strands following their breakage and subsequent reunion in new arrangement. One of the models accounting for molecular recombination leading to chromatid exchange and chiasma formation was first proposed in 1964 by Holliday, and 30 years later still a modified version of his model is favored. Nicks are made by endomuclease at corresponding sites on one strant of each DNA duplex in nonsister chromatid of a bivalent during prophase 1 of meiosis. The nicked strands loop-out and two strands reassociate into an exchanged arrangement, which is sealed by ligase. The remaining intact strand of each duplex is nicked at a site opposite the cross-over, and the exposed ends are digested by exonuclease action. Considerable progress has been made in recent years in the effort to define the molecular and organization features of the centromere region in the yeast chromosome. Centromere core region of the DNA duplex is flanked by 15 densely packed nucleosomes on ons side and by 3 packed nucleosomes on the other side, that is, 2000 bp on one side and 400 400 bp in the other side. All the telomeres of a given species share a common DNA sequence. Two ends of each chromosome are virtually identical. At the end of each chromosome there exist two kinds of DNA sequence" simple telpmeric sequences and telpmere-associated sequencies. Various studies of telomere replication, function, and behabior are now in progress, all greatly aided by molecular methods. During nuclear division in mitosis as well as in meiosis, the nucleili disappear by the time of metaphase and reappear during nuclear reorganizations in telophase. When telophase begins, small nucleoli form at the NOR of each nucleolar-organizing chromosome, enlarge, and fuse to form one or more large nucleoli. Nucleolus is a special structure attached top a specific nucleolar-organizing region located at a specific site of a particular chromosome. The nucleolus is a vertical factory for the synthesis of rRNAs and the assenbly of ribosome subunit precursors.sors.