• The Plant Pathology Journal
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• v.25 no.3
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• pp.247-255
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• 2009

Root-knot nematode species, such as Meloidogyne hapla, M. incognita, M. arenaria, and M. javanica are the most economically notorious nematode pests, causing serious damage to a variety of crops throughout the world. In this study, DNA sequence analyses were performed on the D3 expansion segment of the 28S gene in the ribosomal DNA in an effort to characterize genetic variations in the three Meloidogyne species obtained from Korea and four species from the United States. Further, PCR-RFLP (Polymerase Chain Reaction-Restriction Fragment Length Polymorphism), SCAR (Sequence Characterized Amplified Region) PCR and RAPD (Randomly Amplified Polymorphic DNA) were also utilized to develop methods for the accurate and rapid species identification of the root-knot nematode species. In the sequence analysis of the D3 expansion segment, only a few nucleotide sequence variations were detected among M. incognita, M. arenaria, and M, javanica, but not M. hapla. As a result of our haplotype analysis, haplotype 5 was shown to be common in M. arenaria, M. incognita, M. javanica, but not in the facultatively parthenogenetic species, M. hapla. PCR-RFLP analysis involving the amplification of the mitochondrial COII and large ribosomal RNA (lrRNA) regions yielded one distinct amplicon for M. hapla at 500 bp, thereby enabling us to distinguish M. hapla from M. incognita, M. arenaria, and M. javanica reproduced via obligate mitotic parthenogenesis. SCAR markers were used to successfully identify the four tested root-knot nematode species. Furthermore, newly attempted RAPD primers for some available root-knot nematodes also provided some species-specific amplification patterns that could also be used to distinguish among root-knot nematode species for quarantine purposes.

• Journal of Oriental Neuropsychiatry
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• v.11 no.1
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• pp.1-18
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• 2000

To study the effects of Ramulus et Uncus Uncariae (REUU) on oxygen free radical-mediated damage by hydrogen peroxide $(H_{2}O_{2})$ on cultured spinal sensory neurons, in vitro assays such as MTT assay, NR assay, neurofilament enzymeimmuno assay (EIA), sulforhodamine B (SRB) assay, assay for lactate dehydrogenase (LDH) activity and assay for lipid peroxidation were used in cultured spinal dorsal root ganglion neurons derived from mice, Spinal dorsal root ganglion neurons were cultured in media containing various concentrations of $H_{2}O_{2}$ for 5 hours, after which the neurotoxic effect of $H_{2}O_{2}$ was measured by in vitro assay. The protective effect of the herb extract, Ramulus et Uncus Uncariae (REUU) against H2O2-induced neurotoxicity was also examined. The results are as follows. 1. In NR assay and MTT assay, $H_{2}O_{2}$ significantly decreased the cell viability of cultured mouse spinal dorsal root ganglion neurons according to exposure concentration in these cultures. An additional time course study was done on these cultures. 2. Cultured spinal dorsal root ganglion neurons which were exposed to various concentrations of $H_{2}O_{2}$ showed a quantitative decrease of neuronal cells by EIA and of total protein by sulforhodamine B (SRB) assay, while they showed an increase of both lipid peroxidation and LDH activity. 3. The effect of Ramulus et Uncus Uncariae (REUU) on $H_{2}O_{2}$ induced neurotoxicity showed a quantitative increase in both neurofilament and total protein, but showed a decrease of lipid peroxidation and LDH activity. These results suggest that $H_{2}O_{2}$ has a neurotoxic effect on cultured spinal dorsal root ganglion neurons from mice and that the herb extract, Ramulus et Uncus Uncariae (REUU), was very effective in protecting $H_{2}O_{2}$ induced neurotoxicity by decreasing lipid peroxidation and LDH activity.

• The Plant Pathology Journal
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• v.20 no.1
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• pp.58-62
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• 2004

White root rot of wild white clover (Trifoliorum repens) caused by isolate BWC98-105 has been first reported in Korea. Typical symptoms on root include water-soaked and dark-brown rot, resulting in complete blight of the whole plant. The fungus grew well at $20-28^{\circ}C$ and produced abundant sclerotia at 10-15 days after full mycelial growth on potato dextrose agar. Sclerotia were brown to dark-brown in color and 1-3 mm in length. When white clover plants were inoculated with mycelial suspension ($10^5$ cfu/ml) of isolate BWC98-105, the plant shoots were killed within 4-6 days and the roots were completely blighted. Sclerotia were also formed on the surface of the root covered with whitish mycelia within 10-15 days in the field. All nine isolates developed high incidences of white root rot disease on white clover seedlings, of which the symptoms were similar to those observed in the fields. Hence, their pathogenicity was confirmed on white clover. The infection rate of the fungal isolates varied from 78.5% to 95.2%, among which BWC98-105 was the most virulent isolate. The weeding efficacy of the fungus was maintained until the following year, leading to a significant reduction of reshooting. The fungus was specifically parasitic to white clover, but not to four lawn species including zoysiagrass (Zoysia japonica) under greenhouse test. The fungus also had no response to some Gramineae species including rice, but caused little damage to five species of Leguminosae.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.195-195
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• 2022

Abiotic stress is a major problem in global agriculture as it negatively affects crop growth, yield, and quality. Wheat (Triticum aestivum) is the world's second-highest-producing food resource, so the importance of mitigating damage caused by abiotic stress has been emerging. In this study, we performed GWAS to search for SNPs associated with salt tolerance and drought tolerance. NaCl (200 mM) treatment was performed at the seedling stage using 613 wheat varieties in Korean wheat core collection. Root length, root surface area, root average diameter, and root volume were measured. Drought stress was applied at the seedling stage, and the above phenotypes were measured. GW AS was performed for each phenotype data using the MLM, MLMM, and FarmCPU models. The best salt-tolerant wheat varieties were 'MK2402', 'Gyeongnam Geochang-1985-3698', and 'Milyang 13', showing superior root growth. The significant SNP AX-94704125 (BA00756838) were identified in all models. The genes closely located to the significant SNP were searched within ± 250 kb of the corresponding SNP. A total of 11 genes were identified within the region. NB-ARC involved in the defense response, FKSI involved in cell wall biosynthesis, and putative BP Ml involved in abiotic stress responses were discovered in the 11 genes. The best drought-tolerant wheat varieties were 'PI 534284', 'Moro of Sind', and 'CM92354-33M-0Y-0M-6Y-0B-0BGD', showing superior root growth. This study discovered SNPs associated with salt tolerance in Korean wheat core collection through GWAS. GWAS of drought tolerance is now proceeding, and the GWAS results will be represented on a poster. The SNPs identified by GWAS can be useful for studying molecular mechanisms of salt tolerance and drought tolerance in wheat.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.3
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• pp.192-198
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• 2020

Root extension is the most important growth change that occurs during cultivation. We analyzed growth changes according to young seedling age, temperature, and the degree of root cutting in order to identify factors affecting rooting after transplanting. Root cutting did not affect plant height growth rate, root growth rate was increased in plants that experienced root cutting, and 14-day-old seedlings exhibited a higher growth rate than 7-day-old seedlings. Growth temperature experiments revealed that elongation was high at 25℃ and 28℃, but tended to be low at 18℃, and root elongation was high at 22-28℃ for 7-day-old seedlings and 22-25℃ for 14-day-old seedlings. Nitrogen absorption decreased in the following growth temperature order: 25, 28, 22, 18℃, and differences in nitrogen absorption under different growth temperatures tended to be lower in 7-day-old seedlings. The amount of nitrogen taken up by roots did not differ significantly between the short root treatment and the control, and 7-day-old seedlings tended to start nitrogen absorption faster than 14-day-old seedlings. Root vitality was highest in short-rooted 7-day-old seedlings with 3 cm of root remaining, and vitality also tended to be high in short-rooted 14-day-old seedlings.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.4 s.235
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• pp.511-517
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• 2005

Fretting fatigue is often the root cause of the nucleation of cracks at attachments of structural components. Since fretting fatigue damage accumulation occurs over relatively small volumes, the subsurface cyclic plastic strain is expected to be rather non-uniformly distributed in polycrystalline materials. The scale of the cyclic plasticity and the damage process zones is often on the order of microstructure dimensions. Fretting damage analyses using cyclic crystal plasticity constitutive models have the potential to account for the influence of size, morphology, and crystallographic orientation of grains on fretting damage evolution. Two-dimensional plane strain simulations of fretting fatigue are performed using the cyclic properties of Ti-6Al-4V. The crystal plasticity simulations are compared to an initially isotropic $J_{2}$ theory with nonlinear kinematic hardening as well as to experiments. The influence of initially isotropic versus textured microstructure in the presence of crystallographic slip is studied.

• Smart Structures and Systems
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• v.19 no.4
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• pp.361-369
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• 2017

Electromechanical impedance method as an efficient tool in Structural Health Monitoring (SHM) utilizes the electromechanical impedance of piezoelectric materials which is directly related to the mechanical impedance of the host structure and will be affected by damages. In this paper, electromechanical impedance of piezoelectric patches attached to simply support rectangular plate is determined theoretically and experimentally in order to detect damage. A pairs of piezoelectric wafer active sensor (PWAS) patches are used on top and bottom of an aluminum plate to generate pure bending. The analytical model and experiments are carried out both for undamaged and damaged plates. To validate theoretical models, the electromechanical impedances of PWAS for undamaged and damaged plate using theoretical models are compared with those obtained experimentally. Both theoretical and experimental results demonstrate that by crack generation and intensifying this crack, natural frequency of structure decreases. Finally, in order to evaluate damage severity, damage metrics such as Root Mean Square Deviation (RMSD), Mean Absolute Percentage Deviation (MAPD), and Correlation Coefficient Deviation (CCD) are used based on experimental results. The results show that generation of crack and crack depth increasing can be detectable by CCD.

• Journal of Ocean Engineering and Technology
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• v.35 no.4
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• pp.257-265
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• 2021

Many studies have been performed to predict a reliable and accurate stress-range distribution and fatigue damage regarding the Gaussian wide-band stress response due to multi-peak waves and multiple dynamic loads. So far, most of the approximation models provide slightly inaccurate results in comparison with the rain-flow counting method as an exact solution. A step-by-step study was carried out to develop new approximate spectral moments that are close to the rain-flow counting moment, which can be used for the development of a fatigue damage model. Using the special parameters and bandwidth parameters, four kinds of parameter-based combinations were constructed and estimated using the R-squared values from regression analysis. Based on the results, four candidate empirical formulas were determined and compared with the rain-flow counting moment, probability density function, and root mean square (RMS) value for relative distance. The new approximate spectral moments were finally decided through comparison studies of eight response spectra. The new spectral moments presented in this study could play an important role in improving the accuracy of fatigue damage model development. The present study shows that the new approximate moment is a very important variable for the enhancement of Gaussian wide-band fatigue damage assessment.

• Journal of Veterinary Science
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• v.25 no.4
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• pp.50.1-50.6
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• 2024

Importance: Canine extraction of large carnivores can pose significant risk due to extensive tissue damage during aggressive bone reduction. This report highlights a rare instance in which the use of a piezoelectric surgical unit (PSU) for maxillary canine extraction in a large carnivore resulted in successful outcomes with minimal tissue damage. Case presentation: A 10-year-old male African lion presented with decreased appetite because of bilateral maxillary canine fractures. Intraoral radiographs revealed enlarged root canals and periapical radiolucency of the fractured canines, leading to a diagnosis of periapical periodontitis and pulpitis. To extract the right maxillary canine, conventional method using hand instrument failed to achieve adequate luxation, necessitating the use of the flat blade of the PSU to sever the periodontal ligament. The left maxillary canine was extracted using PSU from the beginning, and the extraction time was markedly shortened by using PSU without additional alveolar bone damage or bleeding. Conclusion and Relevance: This case demonstrated that utilizing PSU for canine extraction in a lion resulted in periodontal ligament separation, reducing damage to the alveolar bone and shortening surgical time. It suggests the promising application of PSU in tooth extraction for large wild animals, indicating its potential significance in veterinary dentistry.

• Plant Biotechnology Reports
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• v.5 no.3
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• pp.225-234
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• 2011

Arabidopsis mutants with T-DNA insertion in seven calmodulin genes (CAM) were used to determine the specific role of CAM in the tolerance of plants to oxidative stress induced by paraquat and hydrogen peroxide ($H_2O_2$) treatments. Arabidopsis calmodulin mutants (cam) were screened for seedling growth, seed germination, induced oxidative damage, and levels of ${\gamma}$-aminobutyric acid (GABA) shunt metabolites. Only the cam5-4 and cam6-1 mutants exhibited an increased sensitivity to paraquat and $H_2O_2$ during seed germination and seedling growth. In response to treatments with $3{\mu}M$ paraquat and 1 mM $H_2O_2$, only the cam5-4, cam6-1 mutants showed significant changes in malonaldehyde (MDA) levels in root and shoot tissues, with highly increased levels of MDA. In terms of the GABA shunt metabolites, GABA was significantly elevated in root and shoot tissues in response to the paraquat treatments in comparison to alanine and glutamate, while the levels of all shunt metabolites increased in root tissue but not in the shoot tissue following the $H_2O_2$ treatments. GABA, alanine and glutamate levels were significantly increased in root and shoot of the cam1, cam4, cam5-4, and cam6-1 mutants in response to paraquat (0.5, 1 and $3{\mu}M$), while they were increased only in the root tissue of the cam1, cam4, cam5-4, and cam6-1 mutants in response to $H_2O_2$ (200 and $500{\mu}M$, 1 mM). These data show that the cam5-4 and cam6-1 mutants were sensitive to the induced oxidative stress treatments in terms of seed germination, seedling growth, and oxidative damage. The accumulation of GABA shunt metabolites as a consequence of the induced oxidative stress treatments (paraquat and $H_2O_2$ treatments) suggests that the GABA shunt pathway and the accumulation of GABA metabolites may contribute in antioxidant machinery associated with reactive oxygen species and in the acquisition of tolerance in response to induced oxidative stress in Arabidopsis seedlings.