• Parasites, Hosts and Diseases
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• 제37권4호
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• pp.237-241
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• 1999

In order to analyze chromosome numbers and karyotypes of intestinal trematodes belonging to the genus, Metagonimus, the gonad tissues of M. takahashii, M. miyatai, and M. yokogawai were prepared and examined. The number of bivalents in the first meiotic division of M. takahashii was nine (n＝9). The diploid number of M. miyatai was observed to be eighteen (2n＝18) and their chromosomes consisted of one pair of metacentric, 7 pairs of submetacentric, and one pair of telocentric chromosomes. The diploid number of M. yokogawai was thirty-two (2n＝32) and the chromosome complements were composed of two pairs of metacentric, 11 pairs of submetacentric, and three pairs of subtelocentric chromosomes. These results could be a supporting evidence for the validity of the new species, M. miyatai, distinct from M. yokogawai.

• Parasites, Hosts and Diseases
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• 제35권4호
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• pp.223-232
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• 1997

Metagonimus miyatai n. sp. (Digenea: Heterophyidae) is described based on adult flukes collected from experimental dogs and hamsters fed with metacercariae encysted in the sweetfish, Plecoglossus altivelis, dace, Tribolodon hakonensis and T. taczanowskii, common fat-minnow. Morocco steindachneri pale chub, Zacco platypus, and dark chub, Zacco temmincki, and on those collected from naturally infected humans. The new species was morphologically compared with M. yokogawai and M. takahashii obtained from experimental animals fed with the sweetflsh and the crucian carp, Cnrossius caressius, respectively. The uterine loops of M. miyatai reached near the posterior end of the body through the space between the two testes, whereas those of M. yokogawai, occupied only the space between the acetabulum and anterior border of two testes. This uterine tubule distribution was similar to that of another closely related species, M. takahashii. However vitellaria of M. miyatai ended in front of the posterior end of the left testis, while those of M. takahcshii reached the posterior end of the left testis and ran it over. By raising M. miyatai as a new species, differentiation of M. yokogawai and M. takahashii became very clear. A key to the species of the genus Metagonimus in the Far East has been proposed.

• Parasites, Hosts and Diseases
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• 제42권3호
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• pp.129-135
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• 2004

We compared the DNA sequences of the genus Metagonimus: M. yokogawai, M. takahashii, and M. miyatai. We obtained 288 D1 ribosomal DNA (rDNA) and mitochondrial cytochrome c oxidase subunit I (mtCOI) fragments from the adult worms by PCR, that were cloned and sequenced. Phylogenetic relationships inferred from the nucleotide sequences of the 28S D1 rDNA and mtCOI gene. M. takahashii and M. yokogawai are placed in the same clade supported by DNA sequence and phylogenie tree analysis in 28S D1 rDNA and mtCOI gene region. The above findings tell us that M. takahashii is closer to M. yokogawai than to M. miyatai genetically. This phylogenetic data also support the nomination of M. miyatai as a separate species.

• Parasites, Hosts and Diseases
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• 제53권5호
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• pp.627-639
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• 2015

Metagonimus yokogawai (Katsurada, 1912) Katsurada, 1912 (Trematoda: Heterophyidae) is parasitic in the small intestine of mammals including man and birds in Far Eastern Russia, Korea, Japan, China, and Taiwan. In the present study, the metacercariae and adults of M. yokogawai were redescribed to designate a neotype of this fluke together with reviews of previous studies including study histories from the first discovery to now. We particularly, attempted to review the study histories and morphological descriptions of M. yokogawai for the species validity, and compared with the morphological characteristics and life cycles of the closely related species, Metagonimus takahashii and Metagonimus miyatai. Finally, we proposed a differential key for the 8 known Metagonimus species distributed in East Asia. Metacercariae were obtained from the body muscles of sweetfish (Plecoglossus altivelis) collected in the Asahi River at Takebe-cho, Kita-ku, Okayama City, Okayama Prefecture, Japan. Adults were recovered from the small intestine of Syrian golden hamsters, to which the metacercariae had been fed 14 days before. A neotype was selected out of the present adult specimens. The Asahi River at Takebo-cho became the type locality of M. yokogawai. In conclusion, the present review shows that M. yokogawai, M. takahashii, and M. miyatai are valid and discriminated by means of morphological characteristics.

• Parasites, Hosts and Diseases
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• 제36권4호
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• pp.217-225
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• 1998

미야타흡충 (Metagonimus miyatai) 피낭유충 및 성충의 표피 미세구조를 주자전자현미경으로 관찰하였다. 피낭유충은 피라미 (Zacco platypus)의 비늘에서 분리하였고, 성충은 흰쥐에 피낭유충을 감염시킨 후 1-4주에 소장으로부터 회수하였다. 탈낭한 피낭유충의 전체적인 외형은 요코가와흡충과 큰 차이가 없었으며, 복흡반은 충체 중앙으로부터 오른쪽에 위치하였다. 구흡반의 구순에는 제I형 감각유두 및 제II형 감각유두가 여러 개 관찰되었다. 복흡반 앞쪽에는 끝이 5-7분지된 피극들이 빽빽하게 덮혀 있었으며, 충체 후반부의 배설공 부근에는 2-3분지된 피극으로 덮혀 있었다. 감염 1주된 성충의 경우, 구흡반의 구순에는 제II형 감각유두 7개가 분포하고 있었으며, 구흡반 내벽에는 큰 제I형 감각유두가 1쌍씩, 작은 제I형 감각유두가 2쌍씩 좌우측에서 각각 관찰되었다. 피극의 분포는 피낭유충의 경우와 비슷하였으나, 분화도는 증가하여 9-11분지된 피극들이 관찰되었다. 감염 2-4주된 성충의 표피 미세구조는 감염 1주된 성충과 대동소이하였으나, 정자가 충체 배측 표면으로 개구된 Laurer＇s canal로 들어가고 있는 것이 관찰되었다. 이상의 결과를 종합할 때, 미야타흡충의 표피 미세구조는 요코가와흡충과 전반적으로 비슷하였으나 피극의 분포 및 분화도, 구흡반 주변의 감각유두 분포 등에 다소 차이가 있음을 알 수 있었으며 이러한 차이가 분류학적으로 의미있는 것일 가능성이 제시되었다.

• Parasites, Hosts and Diseases
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• 제50권3호
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• pp.207-213
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• 2012

The egg morphology of minute intestinal flukes (MIF) that can occur as human infections in the Republic of Korea, i.e., Metagonimus yokogawai, M. miyatai, M. takahashii, Heterophyes nocens, Heterophyopsis continua, Stellantchasmus falcatus, Stictodora fuscata, Pygidiopsis summa, and Gymnophalloides seoi, was studied in comparison with Clonorchis sinensis. The adult worms were obtained from residents of endemic areas, and their intrauterine eggs were studied and measured using light microscopy; the length, width, length-width ratio (LWR), and Faust-Meleney index (FMI). Several specimens were processed for scanning electron microscopy (SEM), and before gold-coating, the uterine portion of each fluke was etched with a sharp pin in order to expose the eggs. The MIF eggs were ovoid, pyriform, or elliptical with a size range of $21-35{\times}12-21{\mu}m$. S. fuscata eggs revealed the highest FMI (largest in the area) and lowest LWR, whereas P. summa eggs showed the lowest FMI and medium LWR. SEM revealed that G. seoi and S. fuscata had remarkably clean shell surface lacking the muskmelon-like structure which is prominent in C. sinensis eggs. In Metagonimus spp., H. continua, H. nocens, and S. falcatus eggs, minute surface ridges were recognizable though less prominent compared with C. sinensis. On the surface of P. summa eggs, thread-like curly structures were characteristically seen. The results revealed that important differential keys for MIF eggs include the length, width, area (FMI), shape of the eggs, and the extent of the muskmelon-like structure or ridges on their shell surface and operculum.

• Parasites, Hosts and Diseases
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• 제38권1호
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• pp.9-15
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• 2000

A scanning electron microscopic study was performed on the surface ultrastructure of metacercariae and adults of Metagonimus takahashii. Metacercariae were collected from the scale of crucian carp (Carassius auratus) , and adult flukes were harvested 1-4 weeks after infection to rats. In excysted metacercariae. the oral sucker had type I (numerous) and type II (seven in total) sensory papillae. Tegumental spines were dense and digitated into 5-7 points on the surface anterior to the ventral sucker, but became sparse and less digitated posteriorly toward the end of the body In adults, seven type II sensory papillae were characteristically arranged around the lip of the oral sucker, and on the inner side of the lip four small and two large type I sensory papillae were symmetrically seen on each side (12 in total). Tegumental spines on anterior two-thirds of the body. were digitated with 9-12 tips ventrally and 8-13 tips dorsally. Sperms entering into the Laurer's canal were observed. The results show that the surface ultrastructure of M. takuhashii is generally similar to those of M. yokogawai and M. miyatai except for the digitation of tegumental spines.