• Parasites, Hosts and Diseases
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• v.32 no.1
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• pp.57-60
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• 1994

In order to search the fate of Thelohonellus kitauei spores the extrusion rates of the polar filaments were monitored in uipo chronologically. Preserved spores suspended with various solutions at $-70^{\circ}C$ showed almost the same vigorous pattern as early freezing stages up to 1,750 days after initial preservation. It revealed that the vlabllltles of some spores suspended with 0.45% and 0.9% NaCl solutions and distilled water at $5^{\circ}C$ continued for 1,628 days, 1,614 days and 1,721 days, respectively. And, the life spans of some spores in the previous solutions added with antibiotics at $5^{\circ}C$ were 1,628 days, 1,614 days and 1,714 days, respectively. Key words: TheLohanellus kitnuei, spore, extrusion rate of polar filament, life span

• Journal of fish pathology
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• v.19 no.2
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• pp.109-117
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• 2006

A new myxosporean species Ceratomyxa oplegnathus n. sp. was found from the gallbladder of cultured rock bream, Oplegnathus fasciatus. Mature spores were 44.14 ± 2.41 (39.04-48.41) ㎛ in length, 8.52 ± 0.36 (7.9-9.26) ㎛ in width in sutural view. Spores contained two spherical polar capsules measuring 3.04 ± 0.2 (2.71-3.37) ㎛ in diameter and a binucleated sporoplasm. Each polar capsule had a 5-6 coiled polar filament, and was situated near the sutural line. In ultrastructural observation, asynchronous divisions of generative cells without pansporoblast formation gave arise to 2 spores within a trophozoite. Sporoplasmic cell in the sporoblast was binucleated, and capsulogenic cells had large amounts of rough endoplasmic reticulum, external tubules, and capsular primordia.

• Current Research on Agriculture and Life Sciences
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• v.1
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• pp.67-83
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• 1983

The new microsporidia S80 isolated from, Bombyx mori L. in Korea showed ovoid in the morphology of the spores and the size were measured $2.9{\pm}0.28{\mu}$ in length and $1.7{\pm}0.29{\mu}$ width. No other microsporidian spore like this has not been so far isolated from Silkworm. The length of the polar filament extruded in hydrogen peroxide ($H_2O_2$) at $30^{\circ}C$ was $26{\mu}$ of a round cytoplasm on the top. The spores were partly stained with Giemsa, Safranin-O and Gram as the same staining properties as Nosema bombycis, Microsporidia K 79 and other microsporidian spores. The fine structures were observed under scanning eleceron microscope through ultrathin sectioning. The spore wall was composed of three layers ; the thin exospore of an electron dense rippled layer, the thick electron lucent endospore which was thinning considerably at the polar filament insertion point, and the inner limiting membrane. Polar cap present at the sporeapex, with a long polar filament of 12-13 coils, subtending angle of $60^{\circ}$ to spore axis, which is tubular made up of a multilayered and are a benes core, light ring structure enclosing the dance core, the dark ring structure enclosing the inner light ring structure and the other than and light ring structure bounded from cytoplasm. Lamellate polaroplast occupied the anterior part of the spore, and the two neclei with dense nucleoplasm bounded by a double nuclear envelope were cited in the slight downer middle portion of spore. From the characteristics of the shape, size and fine structures, it is certain to reason the Microsporidia S80 belong to the phylum Microspora, class Microspora, order Microsporida, order Microsporida. The shape of two nuclei cited seems to be genus Nosema, but in the classification for the suborder it should be defined wheather pansporoblasts be formed or not and for the genis especial attempts have been made to define the characters which distinguish the disporous genera in the life cycle. Survey through the infection of the bad cocoons during 1980 to 1982 in South Korea the areas contaminated with new microsporidia were revealed 5 provinces of Kyung-Gi, Kang-Won, Chung-Nam and Chun-Nam. Pathological effects inoculated per os at second instar larvae of silkworm, the LD 50 was $7.1{\times}10^7/ml$ as lower pathogenecity than that of Nosema bombycis Naegeli of $1.2{\times}10_7/ml$. While on the other hand the inoculation of the microsporidia at fourth instar larvae lowerd the whole cocoon weight and cocoon shell weight and significant at 1% level. The microsporidia S80 defined it can not be transmitted transovarially from the result of predictive and collective examination of 21 egg batches from the infected female moth.

• KSBB Journal
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• v.29 no.4
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• pp.278-284
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• 2014

We present microfluidic method to rapidly analyze the effect of temperature on the change of morphologies of Antarctic bacteria (Pseudoalteromonas sp., Shewanella vesiculosa, Shewanella sp., and Cellulophaga sp.). The microfluidic device is able to generate stable temperature gradient from 7 to$40^{\circ}C$ and dramatically reduce the number of experiments, experimental cost and labor, and amount of sample. Based on this approach, we found that specific bacteria transforming morphology into filament or elongated body strongly depends on cultivation temperature. Interestingly, we found that the morphologies of Pseudoalteromonas sp., Shewanella vesiculosa, Shewanella sp., and Cellulophaga sp. are elongated at below $25^{\circ}C$, above $20^{\circ}C$, above $15^{\circ}C$ and above $35^{\circ}C$, respectively. We envision the microfluidic device is a useful approach to analyze biological events with a high throughput manner.

• Journal of fish pathology
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• v.19 no.1
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• pp.1-6
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• 2006

Numerous large whitish cysts were found on the scale of wild mullet, Mugil cephalus captured in Jin-Hae bay of southern coastal sea of Korea. The cyst consisted of many trophozoites, mature spores and interstitial tissues of host origin. Spores were 8.25 ㎛ (7.26-9.35) in length, 6.3 ㎛ (5.63-6.78) in width, 4.34 ㎛ (3.96-5.04) in thickness. Polar capsules were 4.45㎛ (3.8-5.4) in length and 2.35 ㎛ (1.62-2.86) in width, and the length of polar filament was about 39.57 ㎛ (26.3-56.33). Based on the spore morphology and the host & tissue specificity, the present specimens were identified as Myxobolus episquamalis Egusa, Maeno & Sorimachi, 1990. Deformation of bony plate of the scales and infiltration of inflammatory cells were observed in the histological sections.

• Journal of fish pathology
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• v.36 no.2
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• pp.395-401
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• 2023

Myxosporeans are widespread cnidarian endoparasites in marine and freshwater ecosystems and several species were reported to be a threat to cultured fish causing serious diseases with mass mortality. In the present study, we found a myxosporean species in the genus Thelohanellus from the gills of the cultured common carp (Cyprinus carpio) fingerling for the first time in Korea. The morphological observation showed 500 ㎛ ~ 1 mm size, oval to circular shaped plasmodia containing spores which are pyriform at the anterior end and round at the posterior end (average size 20.1 ㎛ × 9.1 ㎛), with 5 to 6 turns of a single polar filament located in the polar capsule with an average size of 10 ㎛ × 4.6 ㎛. The 18S rRNA sequence was closest to the sequence of T. wangi among Thelohanellus species infecting gills but was not completely identical. Based on the morphological characteristics and molecular analysis results, we classified the present myxosporean parasite as Thelohanellus sp., temporarily. The prevalence and infection intensity of Thelohanellus sp. in the common carp fingerling were very high, which was thought to be the main cause of high mortality.

• Journal of fish pathology
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• v.15 no.3
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• pp.105-110
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• 2002

Thirty five catfish (Silurus asotus) cultured in a fish farm of Jungeup and 222 wild goby (Acanthoguobius flavimanus) caught from the estuary of Mankyoung River, Chonbuk province of Korea were examined the prevalence of myxosporidian infestation. A lot of white spherical myxosporidian cysts in the intestinal epithelium of catfish and the muscle of goby were easily found. The cysts in size were 56 × 73 (42-77 × 59-93 ㎜) in catfish and 2.43 × 0.95 ㎜ in goby. The infection rate (%) were 88.4 in catfish and 89.4 in goby. The Myxosporidians from the intestine of catfish and from the musculature of goby were identified as Myxoborus miyairii and Henneguya tridentigeri on the basis of the shape and structure of the spores under a light microscope. imensions (㎜) of fresh spores of Myxoborus miyairii: length, 11.0-12.0; width, 5.0-6.0; thickness, 3.5-4.0; polar capsule: length, 5.0-5.5; thickness, 1.5-2.0; polar filament: length, 40-45. Dimensions ($\mu{m}$) of fresh spore of Henneguya. tridentigeri: length, 10.0-12.0; width 6.0-8.0; thickness, 4.8; polar capsule: length, 4.6; thickness, 2.6; iodinophilic vacuole: 2.8 × 2.4. No significant pathological change was found from the infected fish. This is the first report on M. miyairii and H. tridentigeri from fish species in Korea.

• International Journal of Industrial Entomology and Biomaterials
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• v.27 no.2
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• pp.282-288
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• 2013

In nature, the population of Nosema bombycis (Microsporidia) causing pebrine disease is small and their development is extremely slow and only few ultimately producing spores. Pebrine infected silkworm, Bombyx mori larvae collected from sericulture field were alive till $3^{rd}$ generation though the concentration of N.bombycis spore was very high ($2.4-3.0{\times}10^8$ spores. $mL^{-1}$). All larvae were died during $4^{th}$ generation with extremely high concentration of pebrine spores ($3.0-4.0{\times}10^9$ spores. $mL^{-1}$) and mostly contain long polar tube (LT). Alternately, all larvae were died immediately (at $3^{rd}$ stage of $1^{st}$ generation) when it was artificially inoculated with same concentration of N.bombycis spores harvested from field ($2.4-3.0{\times}10^8$ spores. $mL^{-1}$) though concentration of spores harvest was very less ($3.0-4.0{\times}10^6$ spores. $mL^{-1}$) and mostly contain short polar tube (ST). Artificially pebrine infected male moth when mated with healthy female moth took six generations to develop pebrine disease and all larvae were died at the $2^{nd}$ stage with very less spore harvest ($3.0-10.0{\times}10^6$ spores. $mL^{-1}$). Survival percentage was increased in all generations (~92.0% at $4^{th}$ generation) when silkworm rearing was conducted under new integrated disease management system.

• Parasites, Hosts and Diseases
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• v.28 no.4
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• pp.241-252
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• 1990

In a basic attempt to develop the prophylactic and therapeutic measures on intestinal giantcystic disease of the Israel carp, C), prinks carpio nudum, the effects of physical and chemical factors on viability or survival of the spores of Thelchcnellus kiteuei were checked in vitro by means of extrusion test on the polar filament. When the fresh spores suspended with 0.45% and 0.9% scdium chloride solution and distilled water were laid at $5^{\circ}C$ and $28^{\circ}C$ for short terms, the extrusion rates increased until the 3rd day, meanwhile when son;e of them were suspended with Tyrode's solution at $-70^{\circ}C$ the rates increased gradually until the 8th day. Viabilities of the spores suspended with 0.9% saline and added antibiotics to the suspension at $5^{\circ}C$ for long terms lasted for 997 days and 1, 256 days (presumed values) at maximum, respectively. The spores suspended with distilled water at $28^{\circ}C$ for long terms survived 152.4 days, but the spores suspended with Tyrode's solution at $-70^{\circ}C$ for long terms showed almost the same viable pattern as early freezing stages up to 780 days. The spores suspended with Tyrode's solution, frozen at $-70^{\circ}C$ and thawed at $5^{\circ}C$, showed the highest rate of extrusion of the polar filament. In the case of frozen spores, the extrusion rates during heating tend to become higher in accordance with the increase of frozen period, and the critical points of 180 day-frozen spores to be killed were generally 78.5 hr. at $60^{\circ}C$, 23.4 hr. at $70^{\circ}C$, 189.1 min. at $80^{\circ}C$ or 10.5 min. at $90^{\circ}C$. The longer the spores were frozen, the more time was needed for the death of spores after thawing; 20 days-17.4 days, 100 days-33.2 days, and 400 days-37.8 days. The longer the spores were frozen, the more time was needed for the death of spores at a conventional when they were dried air drying condition, 540 days-23.5 days, 160 days-21.0 days, and 20 days-14.4 days. On the other hand, the longer the spores were frozen, the more spores were dead rapidly when they were irradiated with 10W UV-ray; 100 days-26.0 hr, 300 days-21.9 hr, and 540 days-13.9 hr. The time needed for killing 200 days-frozen spores by various disinfectants at 1, 000 ppd was 5.2 min. by calcium oxide, 10.4 min. by potassium permanganate, 27.8 min. by malachite green and 14.3 hr. by formalin. Transient inhibitory effects of the extrusion of the polar filament were observed by various antiprotozoal and antifungal agents in the descending order of ketoconazole. metronidasole and dapsone. The above results presume that full drying, followed by spraying CaO and maintaining sunny condition for a few days on the concrete bottoms of knish farm may be an effective method for the prevention of intestinal giant.cystic disease.

• Journal of Microbiology
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• v.40 no.3
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• pp.199-204
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• 2002

A microsporidium, from cabbage white bntteflies, Pieris rapae, collected in Korea, was purified and characterized according to its gene structure, spore morphology and pathogenicity. From the observation of the isolate by SEM and TEM, the endospores, exospores and nuclei, about 12 polar filament coils of the polar tube and posterior vacuoles were all identified. The nucleotide sequence was determined for a portion of genomic DNA which spans the V4 variable region of the small subunit rRNA gene. Comparison with the GenBank database for 15 other microsporidia species suggests that this isolate is most closely related to Nosema species. The pathogenicity against cabbage white butterflies was quantified by inoculating variable doses of spores to the second instar larvae. Peroral inoculation at a dosage of 10$\^$8/ spores/ml resulted in the death of all larvae prior to adult eclosion, but at lower spore dosages of 10$\^$4/-10$\^$5/ spores/ml, many adults successfully emerged. The median lethal dose (LD$\_$50/) was deter-mined to be 4.6$\times$10$\^$6/ spores/ml and the isolate also transmitted transovarially to the progeny eggs at a frequency of 92%.