• ALGAE
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• v.25 no.4
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• pp.197-204
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• 2010

Cytoskeletal changes were observed during cell division of the green alga Zygnema cruciatum using flourescein isothiocynate (FITC)-conjugated phallacidin for F-actin staining and FITC-anti-$\alpha$-tubulin for microtubule staining. Z. cruciatum was uninucleate with two star-shaped chloroplasts. Nuclear division and cell plate formation occurred prior to chloroplast division. Actin filaments appeared on the chromosome and nuclear surface during prophase, and the F-actin ring appeared as the cleavage furrow developed. FITC-phallacidin revealed that actin filaments were attached to the chromosomes during metaphase. The F-actin ring disappeared at late metaphase. At telophase, FITC-phallacidin staining of actin filaments disappeared. FITC-anti-$\alpha$-tubulin staining revealed that microtubules were arranged beneath the protoplasm during interphase and then localized on the nuclear region at prophase, and that the mitotic spindle was formed during metaphase. The microtubules appeared between dividing chloroplasts. The results indicate that a coordination of actin filaments and microtubules might be necessary for nuclear division and chromosome movement in Z. cruciatum.

• Journal of Photoscience
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• v.1 no.1
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• pp.69-73
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• 1994

Sporangiophores (spphs) of Phycomyces blakesleeanus are positively phototropic to unilateral visible (blue) light over a range of fluence rates 10$^{-9}$ to 1 W/m$^2$. The maximal bending angle is always 70-75$\circ$ from the vertical. Many mutants with abnormal phototropism have been isolated. Complementation tests revealed that the genetic grouping is completely consistent with the phenotypic classification scheme, based on sensory responses other than those to light. The spph of the piloboloid mutant, the growth zone of which gradually ceases elongation but expands spherically, and the $\beta$-carotene-overproducing mutant show negative phototropism, in contrast to the wild type spph. We hypothesized that the phototropic orientation of spph is determined by the ratio of the maximal light fluenee rate at the proximal side to that at the distal side of the spph. Based on this hypothesis, we found that the maximal bending angle was larger in thin spphs than in thick ones, and larger in spphs containing smaller amount of $\beta$-carotene than in carotene-rich spphs. In addition to our hypothesis, gravitropic experiments revealed that the maximal bending angle of the wild type spph results from a balance among positive phototropism, negative gravitropism, and the optical properties of the spph. For further advancement of this study, we developed a mutant with a high proportion of uninucleate spores, and designed an efficient microinjection method for obtaining transformants.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.1
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• pp.62-67
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• 2002

An efficient system of rice microspore culture could contribute to the production of genetically modified rice. The microspores were isolated by mechanical or shed methods. The number of microspores per 100 anthers isolated at uninucleate stage was higher than (or similar to) those at binucleate stage in isolation method with pestle or spatular, but microspore divisions were not easily observed on both stages. On the other hand, pollen division in shed pollen culture was observed more frequently at uninuclear than at binuclear stage. Cold pretreatment at 1$0^{\circ}C$ for 10 days resulted in the best multicellular division to produce microcalli at 12.5% efficiency in shed microspores. Heat shock at 33$^{\circ}C$ for one hour before or after pollen shedding enhanced cell division and callus formation. Out of twelve green regenerants, two were haploids and ten were diploids based on the chromosome analysis of root tips. The size of stoma was 12$^{m}$ m in haploids and 15 ${\mu}{\textrm}{m}$ in diploids determined by scanning electron microscope (SEM).

• Mycobiology
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• v.33 no.2
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• pp.69-76
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• 2005

Conidial development of Cordyceps militaris was observed from germinating ascospores and vegetative hyphae through light and scanning electron microscopy (SEM). Ascospores were discharged from fresh specimens of C. militaris in sterile water as well as Sabouraud Dextrose agar plus Yeast Extract (SDAY) plates. We observed ascospore germination and conidial formation periodically. Under submerged condition in sterile water, most part-spores germinated unidirectionally and conidia were developed directly from the tips of germinating hyphae of part-spores within 36 h after ascospore discharge, showing microcyclic conidiation. First-formed conidia were cylindrical or clavate followed by globose and ellipsoidal ones. Germination of ascospores and conidial development were observed on SDAY agar by SEM. Slimy heads of conidia on variously arranged phialides, from solitary to whorl, developed 5 days after ascospore discharge. Besides, two distinct types of conidia, elongated pyriform or cylindrical and globose, were observed in the same slimy heads by SEM. Conidia were shown to be uninucleate with 4,6-diamidino-2-phenylindole staining. Conidiogenous cells were more slender than vegetative hyphae, having attenuated tips. Microcyclic conidiation, undifferentiated conidiogenous hyphae (phialides), polymorphic conidia and solitary, opposite to whorled type of phialidic arrangement are reported here as the characteristic features of asexual stage of C. militaris, which can be distinguished from other Cordyceps species.

• Korean Journal of Plant Tissue Culture
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• v.26 no.3
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• pp.149-156
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• 1999

In order to investigate the effect of low temperature pretreatment on pollen dimorphism and embryo formation in anther culture of Platycodon grandiflorum, the anthers with microspore at the uninucleate stage were cultured on Murashige and Skoog medium supplemented with 0.5mg/L NAA and 1.0 mg/L BA. The low temperature pretreatment have clear effect on the frequencies of S pollen grains, symmetrical binucleate microspores (B type of S pollen), multinucleate and multicelled pollen grains. Especially, after low temperature pretreatment at 8$^{\circ}C$ for 5 days increased the frequency of S pollen grain (20.6%) in vivo. In addition, the highest frequency of callus induction (54.9%) and embryo formation (9.9%) were obtained from the anther pretreatment at 8$^{\circ}C$ or 5 days. Three distinct pathways could be recognized in the androgenesis, one involving mainly the vegetative cell, the second starting with the vegetative and the generative cell, respectively, and the third accompaning with two equal vegetative type cells in the pollen grains.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.3
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• pp.232-241
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• 1984

A series of experiments were carried out to know the effects of pollen stage, cold shock temperature and duration, and media for callus and green plant induction in rice anther culture. The results indicated that: (a) uninucleate stage of pollen was the most suitable stage for effective callus induction, (b) cold shock temperature of 8$^{\circ}C$ and 12$^{\circ}C$ was appeared to be proper temperature for callus induction, (c) callus induction rate was increased in the eight to 12 days long cold storage, (d) the medium N6 was better than that of N6D for callus induction, (e) green plant induction was better in both 4$^{\circ}C$ and 8$^{\circ}C$ than that of 12$^{\circ}C$ cold shock, (f) green plant frequency was higher in eight to 12 days long cold storage and (g) green plant frequency was doubled in the MS medium when compared with N6 medium.

• The Journal of Natural Sciences
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• v.6 no.1
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• pp.71-78
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• 1993

Five $F_1$ hybrids of radish(Raphanus sativus L.) were used in the study for induction of microspore derived embryos. Anthers from the mid-uninucleate to early bicellular stage were inoculated on the modified B5 medium and modified Nitch-Nitch medium supplemented with several growth regulators. The efficiency of anther culture was dspendent on the genotype of donor plants and we obtained various culture efficiency from different genotypes. Induction of embryos from microspore was best result on Nitsch-Nitsch media supplemented with 0.1mg/l NAA and 0.05mg/l BAP. Heat treatments of anthers at $35^{\circ}C$-2days and combined with pretreatment of $4^{\circ}C$ for 2, 8, 12 and 16days . Among the treatments, $35^{\circ}C$-2 days treatment combined with $4^{\circ}C$-2days pretreatment treatment were the most effective in developing embryos from microspores.

• Korean Journal of Plant Resources
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• v.10 no.1
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• pp.86-93
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• 1997

In order to induce somatic embryogenesis from the stem explants and anther of Kalanchoe daigremontiana, the explants were cultured on MS medium supplemented with auxin (2,4-D, IAA, NAA) and/or cytokinin (BAP) for 8 weeks. Callus from explants was induced most efficiently on MS medium containing. 2.0mg/L NAA and 0.2mg/L BAP. Somatic embryogenesis in stem callus was formed by transfering embryogenic callus from induction media containing growth regulators to medium without growth regulators and then to the medium containing auxin and cytokinin (0.1 mg/L IAA and 1.0mg/L BAP). Callus formation occurred actively in the anthers at early uninucleate stage, and by low temperature pretreatment at $4^{\circ}C$ for 3days. Somatic embryogenesis from the anther callus was induced on MS medium containing 1.0mg/L NAA and 1.0mg/L BAP, 2.0mg/L NAA and 0.2mg/L BAP. The tetraploid of 5.4% was obtained among plants regenerated from anthers.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.57 no.4
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• pp.317-323
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• 2012

For the establishment of an efficient embryogenesis from microspore culture in Brassica napus L. domestic cultivar 'Tammiyuchae', four different factors affecting microspore embryogenesis and plantlet regeneration were investigated. The highest embryogenesis rate was achieved when microspores at late uninucleate to early binucleate stage were isolated from flower buds with a length of 3.0~3.5 mm. On average, 388 embryos generated from 1 ml of microspores media. The highest number of embryos was obtained when microspores were subjected to $32.5^{\circ}C$ for 2 days. Embryogenesis of 'Tammiyuchae' was increased with increasing microspore culture density up to about $5{\times}10^4ea/mL$. Gradually higher culture density repressed embryogenesis of microspores. Regeneration rate of shoots from microspore-derived embryos was observed in MS solid medium supplemented with $0.5mg{\cdot}L^{-1}$ NAA and $1.0mg{\cdot}L^{-1}$ BA, and grew well in MS solid medium without plant growth regulators.

• Parasites, Hosts and Diseases
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• v.30 no.4
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• pp.289-298
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• 1992

Acanthamoeba sap., free-living amoebae inhabited in moist soil, pond, freshwater, sewage, atmosphere and swimming pool, may be causative protozoa of the fatal primary amoebic meningoence-phalitis in experimental animals and humans. In this study, Acar,thamoeba spry. , including Acan. thamoeba sp. YM-4 (isolated strain from Korea) had been compared by the two-dimensional electrophoresis and hybridoma technique as well as the difference of morphological characteristics. Trophozoite of Acenthamoeba sp. YM-4 is usually uninucleate and show the hyaline filamentous projections (acanthopoda) . No aagellate stage observed. Cysts have two walls, the outer wall is nearly circular, but inner wall is oval or some irregular. As results of SDS-PAGE for Iysate of Acanthamoeba sp. VM-4, 16 major protein fractions are similiar to those of A. cuzbertsoni, but different to A. royreba and A. polyphaga. Findings of two-dimensional electrophoretic patterns of Acanthamceba sp. YM-4 are almost same to those of A. culberssoni, The isotope of monoclonal antibodies produced from McAY 6, McAY 7, McAY 8, McAY 13 and McAY 16 clones were IgGl, and McAY 10 and McAY 11 clones were IsM. As results of the cross-reactivity among various amoebae using ELISA with monoclonal antibodies, McAY 7 monoclonal antibody (molecular weight 43 kDa by EITB) was only reacted with Acanthamoeba sp. YM-4, but McAY 6 and McAY 10 monoclonal antibodies were reacted to A. cuzbertsoni as well as Acanthamoeba sp. YM-4.