• Korean Journal of Environmental Biology
• /
• v.41 no.4
• /
• pp.657-665
• /
• 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 Journal of Advanced Prosthodontics
• /
• v.5 no.3
• /
• pp.305-311
• /
• 2013

PURPOSE. Over the past years, the adhesion of fiber posts luted with simplified adhesive systems has been a matter of great interest. The aim of this study was to assess the post retentive potential of a self-adhesive resin cement using different adhesive systems to compare the push-out bond strengths of fiber posts. MATERIALS AND METHODS. The post spaces of 56 mandibular premolar roots were prepared and divided into 4 experimental groups and further divided into 2 subgroups according to testing time (n=7). The fiber posts (Rely X Fiber Post) were luted with a self-adhesive resin cement (RelyX Unicem) and one of the following adhesive systems: no adhesive, a total-etch adhesive resin (Single Bond), a two-step self-etch adhesive resin (Clearfil SE Bond) and a one-step self-etch adhesive resin (Clearfil S3 Bond). Each root was cut horizontally, and 1.5 mm thick six root segments were prepared. Push-out tests were performed after one week or three months (0.5 mm/min). Statistical analysis were performed with three-way ANOVA (${\alpha}$=.05). RESULTS. Cervical root segments showed higher bond strength values than middle segments. Adhesive application increased the bond strength. For one week group, the total-etch adhesive resin Single Bond showed higher bond strength than the self-adhesive resin cement RelyX Unicem applied without adhesive resin at middle region. For 3 months group, the two-step self-etch adhesive resin Clearfil SE Bond showed the highest bond strength for both regions. Regarding the time considered, Clearfil SE Bond 3 months group showed higher bond strength values than one week group. CONCLUSION. Using the adhesive resins in combination with the self-adhesive resin cement improves the bond strengths. The bond strength values of two-step self-etch adhesive resin Clearfil SE Bond improved as time passes.

• Korean Journal of Plant Resources
• /
• v.11
• /
• pp.40-47
• /
• 1998

When the leaves, roots and stem segments of seedling of Polygonatum odoratum were cultured on Murashige and Skoog medium with 2.0mg/l BAP, stem segments were the most efficient explants for adventitious shoot inductino. To observe the efficient combination of growth regulators on the adventitious shoot formation , stem segments were cultured on MS medium with various kinds of cytokinins (BAP, kinetin, zeatin). From this experiment, cytokinin treatement was prerequisite for theadventitious shoot formatino,especially BAP was the most effective. Auxin (NAA or IBA) in combination with cyotokinin highly enhanced the adventitious shoot formation. Twenty five percents of explants produced the adventitious shoots on medium with 2.0mg/l BAP solely, while 83% of explants produced the adventitious shoots on medium with 2.0mg/l BAP and 0.1mg/l IBA. Root formationform adventitious shoot was promoted after transfer to 1/2 MS medium supplemented with 0.1mg/l IBA and 0.5mg/l zeatin, thereafter the plantlets with shoots and roots were cultured on 1/2MS medium lacking growth regulators. When the stem segments were cultured to MS medium with 1.0mg/l 2,4 NAA and IBA , yellow and nodulous cali were formed from the stem segments which were developed into adventitious roots. These roots were actively grew after transferred to MS liquid medium lacking growth regulators.

• Korean Journal of Plant Tissue Culture
• /
• v.28 no.1
• /
• pp.1-6
• /
• 2001

The timing for the determination in root formation from nodal and internodal explants of cassava (Manihot esculenta Crantz, cv. MCol 22) was investigated. Nodal explants about 10 mm with an axillary bud formed adventitious roots directly on MS basal medium for 8 days of cultures. But internodal segments without an axillary bud did not develop the adventitious roots on the same medium, and most internodal segments excised from nodal explants after cultures of 5 days on MS basal medium developed adventitious roots. On the other hand, the internodal segments rooted at 90% after cultures on medium with 0.5 mg/L IBA for 5 days, with 1 mg/L IBA for 2.5 days, and with 2 mg/L IBA for 1.5 days respectively. Thus the period of culture on medium with IBA and its IBA concentration affected the rooting rate. Therefore, it is suggested that the determination for root formation occurred before the differentiation of root primordia on medium with IBA, and root inducing factors in medium were absorbed and accumulated during the period of determination for root primordium differentiation in internodal segment of cassava.

• Journal of Plant Biology
• /
• v.33 no.3
• /
• pp.183-188
• /
• 1990

Induction and culture of hairy roots by Agrobacterium rhizogenes A4 were carried out in Platycodon grandiflorum DC. After 2-4 weeks of inoculation with Agrobacterium rhizogenes hairy roots were formed at root segments in the balloon flower. Optimized growth of hairy roots was obtained in hormone-free MS medium, 6% sucrose and pH 5.8. The pattern of ginsenoside in the transformed roots was not different with that in the ordinary roots.

• Journal of Plant Biotechnology
• /
• v.34 no.3
• /
• pp.223-227
• /
• 2007

Plant regeneration system from leaf and root segments of Lycoris chejuensis via bulblet formation was established. Surface-sterilized leaf and root segments were cultured on the B5 medium containing 2,4-D. After 12 weeks of culture onto B5 medium containing 2,4-D, white globular structures and white calluses were formed on the cut surface of the explants. The highest frequency of globular structures and calluses formation from leaf explants was 32.1% when leaf explants were cultured onto B5 medium supplemented with 1 mg/L of 2,4-D. However, the higher concentration of 2,4-D (over than 3 mg/L) resulted in decrease of the frequency. In comparison to leaf explants, root segments showed the highest frequency at a rate of 36.1% when root explants were cultured onto B5 medium supplemented with 3 mg/L of 2,4-D. These structures and calluses were sub-cultured and proliferated onto the same culture medium. Upon transfer to B5 basal medium, white globular structures were developed into bulblets and normal plantlets. After 4 weeks of incubation in the light, plantlets were successfully rooted over the frequency of approximately 90%. Rooted plantlets were successfully transferred to potting soil and acclimatized in the growth chamber. The plant regeneration system of Lycoris chejuensis established in this study, might be applied to mass proliferation, conservation of genetic resources and genetic transformation for molecular breeding.

• Journal of Plant Biotechnology
• /
• v.49 no.3
• /
• pp.230-239
• /
• 2022

Holostemma annulare (Family Asclepiadaceae) is an invaluable vulnerable medicinal plant; the root tubers are used in Ayurveda medicine and by folk healers to treat various ailments. In this study, Schenk and Hildebrandt medium fortified with the cytokinins 6-benzyl adenine, kinetin, and auxins, including indole 3-butyric acid, indole 3-acetic acid, α-naphthaleneacetic acid, and 2,4-dichlorophenoxyacetic acid, were checked for their efficiency on root tuber induction from different explants. Adventitious root tubers were more successfully induced from in vitro leaf segments and shoots when cultured in Schenk and Hildebrandt medium supplemented with 0.5 mg/l of α-naphthaleneacetic acid. In addition, preliminary phytochemical analysis of in vitro root tubers and identification of different secondary metabolites were conducted. Thin layer chromatography and high performance thin layer chromatography analysis of the crude methanolic extracts of the in vitro root tuber identified the presence of lupeol, a bioactive triterpene. Adventitious root tuber induction offers a novel method for the in vitro production of bioactive metabolites that can be scaled up by bioreactors, thus ensuring the conservation and sustainable utilization of H. annulare. The study warrants further scale-up production and pharmacological investigation that can be extended for pharmaceutical needs.

• International Journal of Computer Science & Network Security
• /
• v.23 no.6
• /
• pp.84-90
• /
• 2023

In this article the problem of computing floating-point reciprocal cube root functions is considered. Our new algorithms for this task decrease the number of arithmetic operations used for computing $1/{\sqrt[3]{x}}$. A new approach for selection of magic constants is presented in order to minimize the computation time for reciprocal cube roots of arguments with movable decimal point. The underlying theory enables partitioning of the base argument range x∈[1,8) into 3 segments, what in turn increases accuracy of initial function approximation and decreases the number of iterations to one. Three best algorithms were implemented and carefully tested on 32-bit microcontroller with ARM core. Their custom C implementations were favourable compared with the algorithm based on cbrtf(x) function taken from C ＜math.h＞ library on three different hardware platforms. As a result, the new fast approximation algorithm for the function $1/{\sqrt[3]{x}}$ was determined that outperforms all other algorithms in terms of computation time and cycle count.

• Korean Journal of Plant Resources
• /
• v.24 no.5
• /
• pp.483-488
• /
• 2011

Cacalia firma recently has been used increasingly as leaf vegetables but endangered in natural forest. In this work, we established the plant regeneration via adventitious shoot formation from petiole segments of seedling and in vitro plantlets. Wounding of seed coats and $GA_3$ treatments were effective to induce in vitro germination of seeds, whereas, seed did not germinate at all without these treatment. When cotyledon, leaf, petiole, and root segments of seedling were cultured on medium with 2 $mg{\cdot}L^{-1}$ benzyl adenine (BA) and 0.5 $mg{\cdot}L^{-1}$ naphthaleneacetic acid (NAA), petiole segments showed highest number of shoots per explant among the other segments. Among the various kinds of cytokinins, BA, isopentyl adenine (2-ip), kinetin, zeatin, thidiazuron (TDZ), TDZ and BA treatments were effective to induce high frequency of adventitious shoot formation from petiole segments of in vitro propagated plants. NAA stimulated the frequency of adventitious shoot formation but not for number of adventitious shoots per explants compared to TDZ or BA treatment alone. Most of adventitious shoots were developed directly from surfaces of explants. Adventitious shoots were transferred on medium with IBA for root formation, thereafter the plantlets were successfully transferred to soil.

• Restorative Dentistry and Endodontics
• /
• v.45 no.1
• /
• pp.7.1-7.9
• /
• 2020

Objectives: This study was performed to assess the anatomy of mandibular first molars. Materials and Methods: In this in vivo study, cone-beam computed tomography (CBCT) volumes of 312 bilateral intact first mandibular molars from 156 patients (79 men and 77 women; average age, 35.6 ± 11.2 years) were investigated in terms of the direction of each canal's curvature in the buccolingual and mesiodistal dimensions (direction of the position of the apex in relation to the longitudinal axis of the root), the presence of an isthmus (a narrow, ribbon-shaped communication between 2 root canals) in 3 segments (0-2, 2-4, and 4-6 mm) from the apex), and the presence and number of accessory canals (smaller canals besides the main root canals, connecting the pulp to the periodontium). Data were analyzed statistically (α = 0.05). Results: Mesiolingual canals were mostly buccally and distally inclined, while mesiobuccal and distolingual canals were mostly distally curved. Isthmuses were more common in younger patients (χ² test, p < 0.05). The average numbers of accessory canals in the apical, middle, and coronal segments were 9.9 ± 4.2, 6.9 ± 2.9, and 9.3 ± 3.0 canals per segment, respectively (analysis of variance, p < 0.001). Age and sex were not associated with the number of accessory canals (p > 0.05). Conclusions: The complex anatomy of these teeth deserves attention during non-surgical or surgical endodontic treatment. Around the apex, isthmuses might be more prevalent in younger and female individuals.