• The Journal of the Convergence on Culture Technology
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• v.7 no.4
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• pp.721-726
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• 2021

Plant cells have a totipotencial capacity, the ability of each cell to produce a new complete individual through development. By applying this, several technologies are being developed for widespread application of somatic embryogenesis by processing hormones in vitro as a method of propagation of plants. In order to use this technology, in Kalanchoe pinnata, a plant capable of asexual reproduction with more regular cell division, kinetin belonging to cytokinin and picloram among hormones belonging to auxin were added in combination and treated for 8 weeks, and then the typical performance was evaluated. As a result of our experiment, the rooting effect in leaf slices showed a 70% incidence rate at a picloram concentration of 0.1 mg/L. It has been proven that a concentration difference of 1:5-1:10 in the ratio of kinetin and picloram is effective. It is the experimental result that the effect of auxin is essential for the development of Kalanchoe roots. As for the effect of shooting, the incidence rate was 60% at the picloram concentration of 0.5 mg/L. The kinetin concentration from 0.5 and 1.0 mg/L and has a significant effect on development. It has been proven that the ratio of kinetin to picloram is effective with a concentration difference of 1:1-1:2. These results show that the combination of cytokinin and auxin is crucially important for shooting. It is thought that it can be the basis of a technology for inducing mass proliferation in vitro by inducing direct organogenesis with a combination of hormones.

• Parasites, Hosts and Diseases
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• v.60 no.4
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• pp.241-246
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• 2022

Felids are the unique definitive host of Toxoplasma gondii. The intestine of felid is the only site for initiating Toxoplasma gondii sexual reproduction. T. gondii excretes millions of infectious oocysts from the intestine, which are the primary source of infection. There are many difficulties in developing vaccines and drugs to control oocyst excretion due to the lack of an appropriate experimental model. Here, we established an in vitro feline intestinal epithelial cell (IEC) infection system and an efficient animal model of T. gondii Chinese 1 genotype, Wh6 strain (TgCtwh6). The Kunming mice brain tissues containing TgCtwh6 cysts were harvested 42-day post-infection. The bradyzoites were co-cultured with cat IECs in vitro at a ratio of 1:10. Five 3-month-old domestic cats were orally inoculated with 600 cysts each. The oocysts were detected by daily observation of cat feces by microscopy and polymerase chain reaction. We found that the parasite adhered and invaded cat IECs in vitro, transformed into tachyzoites, and then divided to form rose-like structures. These parasites eventually destroyed host cells, escaped, and finished the asexual reproduction process. Schizonts associated with sexual reproduction have not been observed during development in vitro cultured cells. However, schizonts were detected in all infected cat intestinal epithelial cells, and oocysts were presented in all cat feces. Our study provides a feasible cell model and an efficient infection system for the following studies of T. gondii sexual reproduction, and also lays a foundation to develop drugs and vaccines for blocking excretion and transmission of oocysts.

• Research in Plant Disease
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• v.12 no.2
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• pp.69-74
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• 2006

Basal rot of freesia caused by a Sclerotium sp. occurred at Incheon areas. Incidence of the disease reached up to 45% and averaged 17.0% in the fields. Typical symptoms consisted of sheath dry and leaf blight due to rots on basal leaves. The causal fungus was identified as Sclerotium sp. based on following mycological characteristics. The fungus formed sclerotia on cultural media and plant tissues, but did not produce asexual spores. On cultural medium, aerial mycelia of the fungus changed color from white to clay with cultural age and smelled musty odor. Numerous irregular and elliptical black microsclerotia of the fungus were formed on potato dextrose agar (PDA) after 5 days of incubation at $25^{\circ}C$ and sized $115{\sim}200{\times}95{\sim}150 (av. 145{\sim}126.5){\mu}m$. The fungus grew at $10{\sim}32^{\circ}C$ and $pH 4.0{\sim}8.5$. However, the optimal temperature and pH for mycelial growth of the fungus were $24^{\circ}C$ and 5.5 respectively. The isolate showed present pathogenicity to not only freesia but gladiolus in the pathogenicity test, and the symptoms were similar to those observed in the fields. Basal rot of freesia caused by Sclerotium sp. is firstly reported in Korea.

• Journal of the Korea Organic Resources Recycling Association
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• v.23 no.1
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• pp.70-81
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• 2015

Helicases are known to be a proteins that use the chemical energy of NTP binding and hydrolyze to separate the complementary strands of double-stranded nucleic acids to single-stranded nucleic acids. They participate in various cellular metabolism in many organisms. DEAD-box proteins are ATP-dependent RNA helicase that participate in all biochemical steps involving RNA. DEAD-box3 (DDX3) gene is belonging to the DEAD-box family and plays an important role in germ cell development in many organisms including not only vertebrate, but also invertebrate during asexual and sexual reproduction and participates in stem cell differentiation during regeneration. In this study, in order to identify and characterize DDX3 gene in the earthworm, Perionyx excavatus having a powerful regeneration capacity, total RNA was isolated from adult head containing clitellum. Full length of DDX3 gene from P. excavatus, Pe-DDX3, was identified by RT-PCR using the total RNA from head as a template. Pe-DDX3 encoded a putative protein of 607 amino acids and it also has the nine conserved motifs of DEAD-box family, which is characteristic of DEAD-box protein family. It was confirmed that Pe-DDX3 has the nine conserved motifs by the comparison of entire amino acids sequence of Pe-DDX3 with other species of different taxa. Phylogenetic analysis revealed that Pe-DDX3 belongs to a DDX3 (PL10) subgroup of DEAD-box protein family. And it displayed a high homology with PL10a, b from P. dumerilii.

• The Korean Journal of Mycology
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• v.27 no.6 s.93
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• pp.415-419
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• 1999

Cladobotryum varium infects the fruitbody of Flammulina velutipes during its cultivation. In the early stage of infection, white mycelia of C. varium partially attacked young fruitbody and eventually killed whole fruitbody during fruitbodies development. White fungi pathogen isolated from F. velutipes cultivation farm were investigated in pathogenicity and morphological feautres. The pathogen was identified as Cladobotryum varium. In asexual stage, $2{\sim}4$ conidiophores formed, $8.5{\sim}10.0{\times}16.1{\sim}17.0\;{\mu}m$ long and conidiospores with single septum were shaped in chains, $32.8{\sim}50.4\;{\mu}m$ in size. Size of chlamydospores were $12.7{\sim}18.0{\times}17.7{\times}48.1\;{\mu}m$ with $1{\sim}4$ septa.

• Korean Journal of Microbiology
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• v.41 no.4
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• pp.246-254
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• 2005

Analysis of the complete genome of Neurospora crassa reveals that at least 19 proteins contain tetratricopeptide repeat (TPR) motifs. One of them shows over $60\%$ homology to Ssn6 of Saccharomyces cerevisiae, a universal repressor that mediates repression of genes involved in various cellular processes. Mutant strains generated by RIP (repeat-induced point mutation) process showed four distinctive vegetative growth patterns and slow growth in various rates. Firstly, a mutant showed denser mycelial growth, yellow, csp, and looked like ropy mutant. Secondly, slower growth, dense mycelial, and conidial phenotype. Thirdly, extremely slower growth and aconidial. And finally, flat, tittle aerial hyphae, acon, and similar with a rco-1 RIP mutant. They are all male-fertile, yet female-sterile and produced little or no perithecium. It seems that various phenotypes were occurred depending upon mostly likely, the degree of RIP. These results indicate that this gene may be involved in several cellular possess during vegetative growth, and asexual and sexual development. Therefore it is pleiotropic. Sequence analysis of cDNA shows that it encodes a putative 102 kDa protein composed of 917 amino acids, and has six introns. It is designated rcm-1 (regulation of conidiation and morphology).

• Journal of Korean Society of Forest Science
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• v.42 no.1
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• pp.1-38
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• 1979

The woody species of Genus Ilex which are endemic to Korea are distributed on limited area due to solely temperature factor. There is some differences according to species, however in general, the evergreen Ilex are found along southern coastal area of Korean Peninsula and near islands where the cold index does not exceed $-5^{\circ}C$. But Ilex macropoda and the variety, only deciduous ones, are grown in temperate zone of the peninsula and some islands. The list of Ilex species of Korea are as follows. Ilex cornuta Lindley et Pax., I. crenata Thunb. var. microphylla Max., I. crenata Thunb., I. rotunda Thunb., I. macropoda Miq., I. macropoda Miq. var. pseudo-macropoda Loensner, I. integra Thunb. The author surveyed the populations of Ilex species as many as possible and data of some characters such as leaf shape, spine, fruit shape, stomata density, sex ratio in natural communities, etc. are collected. Almost all the Ilex species in Korea show sporadic distribution. This means quite small sized populations isolate distantly each other eliminating the change of gene exchange in between. Particularly Ilex conuta and I. crenata show the morphological differentiation among populations as well as significant individual variation within a population. These were true with such characteristics, leaf shape, leaf dimension, leaf margin, fruit shape, spine, and stomata density. The founded are that the fruit length and the stomata density counted on the beneath surface of leaves of Ilex cornuta increased with the decrease of latitude. These are naturally closely related with the cold index values. The table shown below indicates the correlation between mean stomata density per $0.3642mm^2$ and cold index values. These relation however were not observed on Ilex crenata. The most dominated natured in relation to individual variation were outline of leaf, the number of marginal spine, the shape of leaf cross section and the degree of luster of the upper leaf surface. As shown in photos 5~7, these variations are agreed at a glance. There are reports that the development of marginal spines in some Ilex species is associated with the juvenility and topophysis. In present study, these two factors were neglected because of the intended sampling procedure. Of Ilex rotunda, population difference with the characteristics of leaf length is recognized but not for leaf width, petiole length, and fruit size. However, individual variations within a population were significantly large. In case of Ilex integra, only individual differences within population were calculated statistically for such characteristics as leaf length, leaf width, and petiole length. As to natural population, the sex ratio was 1:2 (female to male) for Ilex cornuta, and 1:1 for Ilex crenata. The tendency of more male than female in I. cornuta was agreed to other observations. Preparing the tip cutting of length 10cm, and treating with IBA, then attaching earth ball to the cut end, very successful rooting percentages were obtained. Asexual propagation has the advantages of maintaining the heterozygosity of existing varieties and overcoming the difficulties of delayed seed germination frequently encountered with Ilex species. Considering a great deal of variation in morphological traits, a good possibility of selection breeding for decorative and ornamental purposes exists. At present, these evergreen Ilex are ignored by local people as nuisance weedy shrubs. So the proper protection measures should promptly be taken.