• 생태와환경
• /
• 제40권1호
• /
• pp.143-148
• /
• 2007

외래 도입종은 국내 생태계에 빈번히 심각한 문제점들을 일으켜왔고, 이러한 종 중의 하나가 일본에서 도입된 담수어류인 떡붕어 (Carassius cuvieri)이다. 국내 담수생태계에서 떡붕어의 해로운 영향들을 평가하기 위해 우선적으로 선행되어야 할 연구는 형태적으로 가장 유사한 종(Corassius auratus)으로부터 이들을 구분해야 하는 것이다. 전통적인 형태적 동정은 이들 종의 매우 유사한 표현형으로 인해 신뢰할 수 없는 결과들을 자주 보여주기 때문에 더욱 효과적인 방법이 필요하다. 이를 위해 본 연구에서는 3종류의 프라이머(DDF, DDR 그리고 DDR1)를 이용한 효율적인 one-step PCR분자마커를 개발 적용하였다. 이 분자마커는 국내 담수 생태계의 어류 군집 모니터링에 중요한 역할을 할 것으로 기대된다.

• Parasites, Hosts and Diseases
• /
• 제57권3호
• /
• pp.257-264
• /
• 2019

We tried a series of morphological and molecular approaches to identify a new species of Stellantchasmus (Digenea: Heterophyidae) originating from the wrestling half-beaked fish, Dermogenys pusillus of Thailand. Adult worm samples of the new species were recovered from hamsters experimentally infected with the metacercariae from D. pusillus in Thailand. Two isolates (Thai and Korean) of Stellantchasmus falcatus were used as comparative control groups. Worm samples of 3 Stellantchasmus groups were morphologically observed and molecularly analyzed with the mitochondrial cytochrome c oxidase 1 gene. The morphological characteristics of S. dermogenysi n. sp. are similar to S. falcatus originating from brackish water fish, but minor difference was noted including the absence of the prepharynx, position of the ovary near the ceca end, smaller body size, and shorter esophageal length. A phylogenetic tree derived from neighbor-joining and maximum-likelihood methods suggests that S. dermogenysi n. sp. is separated from S. falcatus supported by high bootstrap values. The relative divergences persist between these host-specific trematodes, which we suggest should be recognized as 2 distinct species. Comparisons of S. dermogenysi n. sp. with S. falcatus isolated from mullets in Thailand and Korea indicate a genetic divergence of mitochondrial DNA of 19.4% and 21.7%, respectively. By the present study, a new species, Stellantchasmus dermogenysi n. sp. (Digenea: Heterophyidae), is proposed in Thailand based on molecular evidences, in addition to minor morphological differences between S. falcatus and the new species.

• 한국어병학회지
• /
• 제34권2호
• /
• pp.255-259
• /
• 2021

This is the first report describing acute mass mortality occurred in juvenile olive flounder (Paralichthys olivaceus) caused by gas bubble disease (GBD). A total of 610 fish (average weight = 35 g), which were more than half of the fish acclimated at 17℃ in an aquarium, were killed within two days of acclimation. The dead and moribund fish showed excessively opened opercula and mouths, and occasionally, severe exophthalmia. Through microscopic observation, numerous gas emboli were found in the gills of the dead and live fish, while the fish were not infected with any microbial pathogens. The dissolved oxygen (DO) saturation level of the rearing water and seawater nearby the facility reached 145% and 286%, respectively, whereas other water quality parameters (such as salinity, pH, and chemical oxygen demand) were normal. The extreme saturation rate of seawater in the shore nearby seemed to be due to an enormous algal bloom that occurred there. Through molecular identification based on 18S rDNA sequences, the most dominant algal species was most closely related to Ulva californica (99.87% sequence identity) followed by U. prolifera, U. linza, and U. curvata (99.81%). Therefore, it can be concluded that supersaturated seawater due to mass algal bloom caused gas bubble disease in the olive flounder, leading to mass mortality. After technical adjustment, such as increased aeration, lowered water circulation rate, and inlet water filtration using micro-pore carbon filters, the DO level became normal, no further mortality occurred and the status of the fish was stabilized.

• 한국수산과학회지
• /
• 제55권2호
• /
• pp.195-206
• /
• 2022

The separation of spectrally overlapped broadband echo signals from free-swimming Japanese needlefish Hypohamphus sajori using the fractional Fourier transform (FrFT) was investigated. The broadband echo signals were measured over frequency ranges of 40-80 and 110-220 kHz. The overlapped echo signals were separated after eliminating noise signals in the smoothed pseudo-Wigner-Ville distribution domain. The echo signal from a 40 mm WC sphere suspended just below a chirp transducer was used to calibrate the broadband of the chirp echo sounder and estimate the frequency dependence of target strength for the separated echo signals. The experimental results show that the proposed FrFT method can analyze the time-frequency image of broadband echo signals from free-swimming individual fish effectively and can be used as a quantitative tool for extracting the acoustic features used for fish species identification.

• 약학회지
• /
• 제30권5호
• /
• pp.253-265
• /
• 1986

Among 230 species of herbal drugs screened, thirty one show the anthelmintic activities in vitro against Clonorchis sinensis, the chinese liver fluke. The active substances have been isolated and their structures identified. Some of the active substances and their derivatives have been synthesized, followed by anthelmintic activity tests. The extracts from the active drugs cause damages in organs of the adult worm in the hepatic duct of rabbit. Some fresh water fish, which function as bad hosts for the fluke, excrete defense substances against the cercaria of the fluke. The defense substances have been isolated from Cyprinus carpio and Cyprinus carpio nudus, followed by structural identification. The results are summarized as follows: l) The bark of Machilus thunbergii as well as the seed of Schizandra chinensis contain meso-dihydro-guaiaretic acid as the anthelmintic component. Among derivatives synthesized, 4-phenyl-1-((3, 4-dihydroxyphenyl)-, 4-phenyl-1-(3-hydroxy-4-methoxy phenyl)-and 4-phenyl-1-(4-hydroxy-3-methoxy phenyl)-2, 3-dimethyl butanes show considerable activities. Administration of the bark extract mainly damages the bladder of the adult worm. 2) The active substance from the roasted fruit of Prunus mume is 2-hydroxymethylfurfural. This substance is produced during the roasting process. Administration of the fruitextract causes a damage of the bladder of the adult worm. 3) The active substance from the root of Scutellaria baicalensis is 5.2'-dihydroxy-6, 7, 8, 6'-tetramethoxyflavone. 4) Beside alantolactone, a very strong anthelmintic component is contained in the root of Inula helenium. Administration of the root extract causes irreversible damage on the worm, affecting mainly the reproductive organs. 5) The cercaricidal substances from the epidermis of C. carpio and C. carpio nudus are ethyl linoleate and linoleic acid, respertively. 6) The cercaricidal substances from various kinds of fresh water fish have different $R_f$ values, implying that the defense substances are species-specific. Unexpectedly, the fish with good host function, for example Pseudorasbora parva, excrete the defense substances, too. The defense substances are possibly organ-specific in individual species; the organs essenstial for the existence of the species excrete the defense substances, allowing other parts to be invaded by the cercaria. 7) The cercaricidal fraction of Carassius carassius is detected only in the fish which have been collected during the summer time from May to September, Its secretion is not dependent on water temperature. Thus, it seems to be possible that the secretion of the defense substance would be stimulated through a contact between the fish and cercaria.

• Journal of Microbiology and Biotechnology
• /
• 제27권9호
• /
• pp.1593-1601
• /
• 2017

Vibrio species are generally recognized as pathogens predominant in seafood along coastal areas. The food industry has sought to develop efficient microbial detection methods. Owing to the limits of conventional methods, this study aimed to establish a rapid identification method for Vibrio isolated from Korea, based on matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Four different preparation procedures were compared to determine the appropriate means to pretreat Vibrio species, using 17 isolates and five reference strains. Extended direct transfer and full formic acid extraction methods using bacterial colonies on agar plates revealed very low identification rates. Formic acid and trifluoroacetic acid (TFA) extractions using bacterial broth cultures were also performed. All Vibrio isolates and reference strains prepared by TFA extraction were successfully identified to the species level (17/22, 77.3%) and to the genus level (5/22, 22.7%). Thus, TFA extraction was considered the most appropriate method to pretreat Vibrio species for MALDI-TOF MS. The remaining 33 isolates and two reference strains were prepared by TFA extraction and analyzed by MALDI-TOF MS. Overall, 50 isolates were identified to the species level (40/50, 80%) and to the genus level (10/50, 20%). All isolates were identified as 43 V. alginolyticus, six V. parahaemolyticus, and one V. vulnificus species. V. alginolyticus and V. parahaemolyticus were isolated from fish offal (87.5% and 12.5%, respectively), seawater (91.3%, 8.7%), and shellfish (62.5%, 37.5%), whereas V. alginolyticus and V. vulnificus were isolated from sediment (90.9% and 9.1%, respectively). This study established a reliable system of MALDI-TOF MS preparation and analysis for Vibrio identification.

• Parasites, Hosts and Diseases
• /
• 제53권6호
• /
• pp.683-688
• /
• 2015

Human diphyllobothriasis is a widespread fish-borne zoonosis caused by the infection with broad tapeworms belonging to the genus Diphyllobothrium. In mainland China, so far 20 human cases of Diphyllobothrium infections have been reported, and the etiologic species were identified as D. latum and D. nihonkaiense based on morphological characteristics or molecular analysis. In the present study, proglottids of diphyllobothriid tapeworms from 3 human cases that occurred in Heilongjiang Province, China were identified as D. nihonkaiense by sequencing mitochondrial cytochrome c oxidase subunit I (cox1) and NADH dehydrogenase subunit 5 (nad5) genes. Two different cox1 gene sequences were obtained. One sequence showed 100% homology with those from humans in Japan. The remaining cox1 gene sequence and 2 different nad5 gene sequences obtained were not described previously, and might reflect endemic genetic characterizations. D. nihonkaiense might also be a major causative species of human diphyllobothriasis in China. Meanwhile, the finding of the first pediatric case of D. nihonkaiense infection in China suggests that infants infected with D. nihonkaiense should not be ignored.

• Fisheries and Aquatic Sciences
• /
• 제25권12호
• /
• pp.637-647
• /
• 2022

A spotted scat, Scatophagus argus, has a high nutritional value and is among Asia's most widely consumed fish species. Thua Thien Hue's consumption market considers this species to be of high economic value and requires protection and conservation of the population. However, the studies on the identification and genetic diversity of S. argus distributed in Vietnam are still lacking. Therefore, mitochondrial cytochrome c oxidase subunit I (COI) gene was utilized to distinguish different populations and investigate the genetic diversity of two populations of S. argus from Tam Giang lagoon, Thua Thien Hue province (n = 31) and Ca Mau province (n = 14). The sequencing results indicated 13 distinct haplotypes among 45 sequences. Five single nucleotide polymorphisms were observed to distinguish Hue spotted scat population. The S. argus population in Ca Mau province was higher haplotype diversity (Hd) and nucleotide diversity (π) than those of Thua Thien Hue province, which demonstrates that there are minor differences between haplotypes. There were genetic distances ranging from 0%-4% within the populations and 6.67% between the two populations. In addition to the sequencing, the comparison of morphology, biology, culture, and the growth rate was sufficient to distinguish the spotted scat S. argus in Thua Thien Hue from Ca Mau.

• 한국수산과학회지
• /
• 제53권1호
• /
• pp.74-82
• /
• 2020

Dragonet fish (Callionymidae), living in benthic upper 900 m of all subtropical, tropical and temperate oceans, comprises 200 species in 20 genera worldwide, of which 18 species in 6 genera occur in Korea. Although dragonet fish plays an important role in linking between top predators and lower trophic levels, there are only few studies about their early life history. Herein, we present molecular and morphological data on larvae and juveniles of Bathycallionymus kaianus (Günther, 1880) collected from the Korean waters. During 2016 to 2018, one preflexion larvae [2.69 in total length (TL)], three flexion larvae (3.65 and 4.77 mm TL), six postflexion larvae (6.07 and 7.94 mm TL), and three juveniles (10.81 and 12.26 mm TL) were collected in the East Sea, Korea Strait, and Jeju Island using Bongo net. Of them, 13 individuals were identified through molecular markers (COI or 16S rRNA) and morphologically described. The larvae of B. kaianus are well distinguished from other species of Callionymidae in melanophore distribution, body shape and development of preopercular spine. It was very similar to larvae of two Repomucenus species, R. valenciennei and R. virgis, but was clearly distinguished in melanophore distribution, preopercular spine development, and head shape.

• 한국어류학회지
• /
• 제36권2호
• /
• pp.188-192
• /
• 2024

동갈돔과에 속하는 Apogon erythrius 1개체(표준체장 44.3 mm)가 2009년 10월 제주도 사계 연안 통발에서 처음으로 채집되었다. 본 종은 등지느러미 앞(predorsal)의 비늘수가 5~6개, 새파수 7~9개이며, 제2등지느러미 극조를 눕혔을 때 제2 등지느러미 기저의 중간을 지나지 않는 점, 비늘의 말단이 진한 분홍색을 띠는 점 등의 특징을 갖는다. 형태 기반의 종 동정을 확인하기 위해 분자 동정을 한 결과, 채집된 개체는 기존에 보고된 Apogon erythrinus의 염기서열과 잘 일치하였다. 몸 크기에 비해 눈이 커서 이 종의 국명을 "큰눈얼게비늘"로 제안한다.