• 한국미생물·생명공학회지
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• 제31권2호
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• pp.117-123
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• 2003

공시균인 Saccha. erythraea IFO 13426으로부터 VB-C에 의한 erythromycin 생산 유도능이 시사된 바 있으므로, 공시균으로부터 VB-C와 특이적으로 결합하는 autoregulators 및 receptor gene을 탐색하여, EM의 생산 조절 기구를 규명하고자 하였다. 탐색의 일환으로 기존의 Streptomyce속 receptor gene의 공통배열을 primer로 이용하여 PCR을 수행하였고, 예상 크기인 120bp의 단편을 pUC19 vector에 ligation하여 E. coli DH5$\alpha$에 형질전환한 후, plasmid를 분리하여 BamHI을 처리하여 2% agarose gel에 전기영동한 결과, pUC19 (2.7kbp)외에 receptor gene PCR 산물이 120bp위치에 존재하는 것을 확인하였다. 형질전환된 plasmid로 PCR을 수행하여 염기배열을 결정한 후 해석한 결과 Streptomyces sp. 유래의 receptor gene과 유사함을 확인하였다. 따라서 Saccha. erythraea IFO 13426에는 항생물질인 erythromycin의 생산에 관여한다고 추정되는 autoregulator receptor protein을 코드하는 유전자가 존재할 것으로 예상되어 120 bp의 PCR product를 probe로 이용하여 Southern 및 colony hybridization을 통하여 3.2 kbp의 SacI 단편을 가지는 plasmid(pESG)를 제작하였고, 이를 sequencing한 결과, autoregulator receptor protein 유전자가 KpnI과 SalI을 포함하는 영역에 존재한다는 것을 알 수 있었으며 이를 EsgR이라 명명하였다. 유전자 해석 결과, EsgR은 205개의 아미노산으로 구성되어 있으며, 이는 기존의 autoregulator receptor proteins과 비교시 30%이상의 상동성을 나타내었으며, 기존의 autoregulator receptor prorein들이 하부의 항생물질 생합성 유전자들의 제어를 위해 보유하고 있는 helix-turn-helix DNA binding motif를 EsgR이 보유하고 있는 점에서, EsgR은 Saccha. erythraea가 보유하는 autoregulator receptor protein을 code하는 유전자로 추정되었다.

• Parasites, Hosts and Diseases
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• 제55권3호
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• pp.341-345
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• 2017

The metacercariae of Artyfechinostomum malayanum (Leiper, 1911) Mendheim, 1943 were discovered in Pila sp. snails purchased from a market in Phnom Penh, Cambodia. They were isolated from the snails using the artificial digestion technique and were orally fed to 2 hamsters, 1 rat, and 2 mice to obtain the adult flukes. The metacercariae were round, $145-165{\mu}m$ in diameter, having a cyst wall of $6-10{\mu}m$ in thickness, a head collar and collar spines, and characteristic features of excretory granules. Adult flukes were recovered in the small intestines of the animals at days 14 and 32 post infection and were morphologically observed using a light microscope and a scanning electron microscope. They were plump or elongated, ventrally curved, $6.0-8.1{\times}1.6-2.0mm$ in size, and characterized by the head collar bearing 43 collar spines, including 5 end group ones on each side, a long cirrus sac extending beyond the posterior margin of the ventral sucker, a submedian ovary, and 2 deeply lobed testes. Eggs in uteri were operculate, ovoid to ellipsoid, and $120-135{\times}68-75{\mu}m$ in size. In scanning electron microscopy, the head collar was prominent with collar spines looking like horns. Scale-like tegumental spines were densely distributed on the ventral surface between the head collar and ventral sucker. Sensory papillae were distributed mainly on the tegument around suckers. By this study, it has been first confirmed that the life cycle of A. malayanum exists in Cambodia.

• Parasites, Hosts and Diseases
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• 제58권4호
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• pp.431-443
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• 2020

Echinostoma mekongi n. sp. (Digenea: Echinostomatidae) is described based on adult flukes collected from humans residing along the Mekong River in Cambodia. Total 256 flukes were collected from the diarrheic stool of 6 echinostome egg positive villagers in Kratie and Takeo Province after praziquantel treatment and purging. Adults of the new species were 9.0-13.1 (av. 11.3) mm in length and 1.3-2.5 (1.9) mm in maximum width and characterized by having a head collar armed with 37 collar spines (dorsal spines arranged in 2 alternative rows), including 5 end group spines. The eggs in feces and worm uterus were 98-132 (117) ㎛ long and 62-90 (75) ㎛ wide. These morphological features closely resembled those of Echinostoma revolutum, E. miyagawai, and several other 37-collar-spined Echinostoma species. However, sequencing of the nuclear ITS (ITS1-5.8S rRNA-ITS2) and 2 mitochondrial genes, cox1 and nad1, revealed unique features distinct from E. revolutum and also from other 37-collar-spined Echinostoma group available in GenBank (E. bolschewense, E. caproni, E. cinetorchis, E. deserticum, E. miyagawai, E. nasincovae, E. novaezealandense, E. paraensei, E. paraulum, E. robustum, E. trivolvis, and Echinostoma sp. IG). Thus, we assigned our flukes as a new species, E. mekongi. The new species revealed marked variation in the morphology of testes (globular or lobulated), and smaller head collar, collar spines, oral and ventral suckers, and cirrus sac compared to E. revolutum and E. miyagawai. Epidemiological studies regarding the geographical distribution and its life history, including the source of human infections, remain to be performed.

• 한국식물병리학회지
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• 제11권4호
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• pp.367-373
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• 1995

The cDNAs derived from the coat protein (CP) genes of six plant RNA viruses, tobacco mosaic virus-pepper strains (TMV-P) and -ordinary strain (TMV-OM), potato virus Y (PVY), turnip mosaic virus (TuMV), cucumber mosaic virus (CMV) and potato leafroll virus (PLRV), were subcloned into the transcription vector, pSPT18, containing SP6 and T7 promoters. The digoxigenin (DIG)-labeled RNA polymerase after linearlization of the cloned pSPTs with XbaI or SacI, and were tested for their sensitivities for the detection of the six viruses. In slot-blot hybridization, dilution end points for the detection of TMV-P and TMV-OM were 10-4, while those of PVY, TuMV and CMV were 10-3. PLRV was detected at the dilution of 10-2. When each RNA probe was applied for the detection of the viruses in the preparations from the leaf disks (8 mm in diameter, and 12 to 15 mg in weight) of infected natural host plants, TMV-P, TMV-OM and TuMV could be detected from one disk, while PVY from 1 or 2 disks. CMV was detected in the preparation from two disks, and PLRV from three disks. With DIG-labeled RNA probe, PVY was detected at 5 days after inoculation, but with ELISA the virus was detected at 8 days after inoculation to tobacco (Nicotiana tabacum cv. Xanthi nc) plants on which symptoms appeared at 9 days after inoculation. No difference was observed in cross reaction between the RNA probes for the detection of TMV-P and TMV-OM.

• Parasites, Hosts and Diseases
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• 제26권1호
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• pp.65-68
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• 1988

경상남도 남해 지방산 숭어에서 Stellantchasmus falcatus의 길낭유충을 발견하고 횐쥐에 감염시킨 후 성충을 얻어 동정하였다. 검사한 숭어는 모두 10마리로서 크기 20~30cm이었고 그중 3마리에서 S. falcatus로 생각되는 퍼낭유충이 470개 검출되었다. 피낭유충은 원형 또는 타원형으로 크기 $0.15~0.20{\times}0.13~0.19mm$이었고 대부분이 숭어의 근육에서 발견되었다. 총 280개의 피낭유충을 횐쥐 5마리에 각각 30~100개씩 나누어 감염시키고 7~10일후에 흰쥐를 희생시켜 소장(소장) 내용물을 검경한 바 총 83마리의 성충이 회수되었다. 회수된 충체는 길이 0.41~0.70mm, 폭 0.32~0.39mm이었고, 장낭형(장낭형 ; elongated sac-like)의 expulsor를 가진 저정낭(seminal vesicle) 등 몇가지 형태학적 특징을 근거로 S. ialcatus Onji et Nishio, 1915로 동정되었다. 이 연구로 우리나라에서도 숭어가 S. falcatus의 제2중간숙주역할을 하고 있음이 확인되었고 이 홉충의 인체감염원이 되고 있을 것으로 추측되었다.

• Parasites, Hosts and Diseases
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• 제49권4호
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• pp.457-460
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• 2011

Adults of Maritrema obstipum (Digenea: Microphallidae) were found in the intestines of 4 species of migratory birds, including the sanderling (Crocethia alba), Kentish plover (Charadrius alexandrines), Mongolian plover (Charadrius mongolus), and red-necked stint (Calidris ruficollis), collected from Yubu Island, Chungcheongnam-do, Korea. The worms of were $451{\times}265{\mu}m$ in size, and were easily identifiable as Maritrema species by the presence of the cirrus sac, and the ring-like distribution of the vitellaria. More specifically, the ejaculatory duct curved posteromedially, and the 2 parts of vitelline follicles were found to be distinct at the posterior end. The eggs were brown-colored, and $19.8{\times}12.3{\mu}m$ in size. All these findings implicated M. obstipum as the pertinent species of the worms. Beside these, adult worms of Gynaecotyla squatarolae, Parvatrema duboisi, and Acanthoparyphium sp. were also discovered. This is the first report establishing migratory birds as the natural definitive hosts for M. obstipum.

• Parasites, Hosts and Diseases
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• 제58권4호
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• pp.467-473
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• 2020

Chinese edible frogs, Hoplobatrachus rugulosus, were examined to estimate the potential risks of human gnathostomiasis and sparganosis in Myanmar. A total of 20 frogs were purchased in a local market of Yangon and examined with naked eyes and the artificial digestion method after skin peeling in June 2018 and June 2019. Larvae of gnathostomes and Spirometra (=spargana) were detected in 15 (75.0%) and 15 (75.0%) frogs with average intensities of 10.5 and 6.3 larvae per infected frog, respectively. Gnathostome larvae were 2.75-3.80 (av. 3.30) mm long and 0.29-0.36 (0.33) mm wide. They had a characteristic head bulb with 4 rows of hooklets, a muscular long esophagus, and 2 pairs of cervical sac. The mean number of hooklets were 41, 44, 47, and 50 on the 1st, 2nd, 3rd, and 4th row, respectively. Collected spargana were actively moving, particularly with the scolex part, and have ivory-white color and variable in size. Conclusively, it has been first confirmed that Chinese edible frogs, H. rugulosus, are highly infected with larval gnathostomes and spargana in this study. Consuming these frogs is considered a potential risk of human gnathostomiasis and sparganosis in Myanmar.

• 한국양식학회지
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• 제11권1호
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• pp.49-58
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• 1998

우리나라 특산 어종인 꺽지의 산란습성, 초기생활사에 관하여 조사하였다. 산란기는 자연 상태에서 5~6월이며, 한 마리의 암컷이 여러 번 산란에 참여한다. 꺽지의 성숙한 어미들은 큰 돌 아래쪽에 알을 한층으로 점착하여 산란하며, 수컷이 부화하여 후기자어기까지 보호한다. 알의 크기는 2.60~3.04mm로 여러개의 유구를 가지고 있으며, 유구의 크기는 0.10~0.64mm이다. 부화는 사육수온 19$\pm$1.$0^{\circ}C$에서 수정후 380시간째부터 시작되어 392시간만에 완료된다. 부화직후의 자어는 전장 6.45~7.34mm(평균 6.85mm)로 입과 항문이 열려 있고, 흑색소포는 머리부분, 난황 윗부분, 복부의 등쪽에 분포한다. 부화후 3일째 자어는 평균 전장 7.25mm로 이때부터 Daphnia sp.와 Brachionus plicatilis를 왕성하게 섭이한다. 부화후 6일째의 자어는 전장 7.94~10.10mm(평균 9.00mm)로 난황은 대부분 흡수되어 후기자어기로 접어들며, 척색의 끝부분은 45도로 위로 굽어져 있다. 부화후 30일째의 자어는 전장이 16.90~19.80mm(평균 18.20mm)로 체고는 현저하게 높아지고, 모든 지느러미 줄기가 정수에 달하여 치어기로 이행한다. 부화후 50일째의 치어들은 전장이 24.60~27.10mm(평균 25.90mm)로 몸의 형태, 체색 및 옆줄이 완전하게 형성되어 성어에 닮아간다.

• Journal of Microbiology and Biotechnology
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• 제16권1호
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• pp.77-83
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• 2006

A gene encoding a $\gamma-butyrolactone$ autoregulator receptor was cloned from Saccharopolyspora erythraea, and the biochemical characteristics, including the autoregulator specificity, were determined with the purified recombinant protein. Using primers designed for the conserved amino acid sequence of Streptomyces $\gamma-butyrolactone$ autoregulator receptors, a 120 bp S. erythraea DNA fragment was obtained by PCR. Southern and colony hybridization with the 120 bp fragment as a probe allowed to select a genomic clone of S. erythraea, pESG, harboring a 3.2 kb SacI fragment. Nucleotide sequencing analysis revealed a 615 bp open reading frame (ORF), showing moderate homology (identity, $31-34\%$; similarity, $45-47\%$) with the $\gamma-butyrolactone$ autoregulator receptors from Streptomyces sp., and this ORF was named seaR (Saccharopolyspora erythraea autoregulator receptor). The seaR/pET-3d plasmid was constructed to overexpress the recombinant SeaR protein (rSeaR) in Escherichia coli, and the rSeaR protein was purified to homogeneity by DEAE-Sephacel column chromatography, followed by DEAE-ion-exchange HPLC. The molecular mass of the purified rSeaR protein was 52 kDa by HPLC gel-filtration chromatography and 27 kDa by SDS-polyacrylamide gel electrophoresis, indicating that the rSeaR protein is present as a dimer. A binding assay with tritium-labeled autoregulators revealed that rSeaR has clear binding activity with a VB-C-type autoregulator as the most effective ligand, demonstrating for the first time that the erythromycin producer S. erythraea possesses a gene for the $\gamma-butyrolactone$autoregulator receptor.

• Parasites, Hosts and Diseases
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• 제49권4호
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• pp.449-455
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• 2011

We detected metacercariae of Echinostoma revolutum in Filopaludina sp. snails purchased from a local market in Nam Dinh Province for the first time in Vietnam. Adult flukes were harvested from experimentally infected hamsters at days 14 and 17 post-infection. The metacercariae were round, $170-190{\mu}m$ (n=15) in diameter, with a cyst wall thickness of about $12{\mu}m$. A total of 37 collar spines were arranged around the head collar, and large excretory granules were seen in 2 canals of the excretory bladder. The 14-day old adult flukes were elongated, ventrally curved, and $5.0-7.2{\times}0.8-1.3mm$ (n=20). The head collar had a total of 37 collar spines arranged in 2 alternating rows, including 5 corner spines on each side. The cirrus sac contained a saccular seminal vesicle, a prostatic gland, and an unarmed cirrus. Two tandem testes were smooth or slightly lobed. Eggs were ovoid to elliptical, $110-118{\times}70-75{\mu}m$. These morphological characters were similar to those of E. revolutum and E. jurini. We tentatively identified it as E. revolutum because the validity of E. jurini remains to be elucidated. The taxonomic relationship of E. revolutum and E. jurini is discussed.