• Parasites, Hosts and Diseases
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• 제48권1호
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• pp.49-55
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• 2010

In vitro cultivation of trematodes would assist studies on the basic biology of the parasites and their hosts. This is the first study to use the yolk of unfertilized chicken eggs as a simple and successful method of ovocultivation and the first time to obtain the adult-stage of the trematode Cymatocarpus solearis Braun, 1899 (Digenea: Brachycoeliidae). Chicken eggs were inoculated with metacercariae from the muscle of the spiny lobster, Panulirus argus (Latreille, 1804). The metacercariae were excysted and incubated for 576 hr (24 days) at $38^{\circ}C$ to obtain the adult stage. Eggs in utero were normal in shape and light brown color. The metacercariae developed into mature parasites that have been identified as the adultstage found in marine turtles. The adult lobsters collected in Quintana Roo State, Mexico, showed the prevalence of 49.4% and the mean intensity of 26.0 per host (n=87). A statistical study was performed to determine that no parasitic preference was detected for male versus female parasitized lobsters. Morphometric measurements of the adult-stage of C. solearis obtained in our study have been deposited in the National Helminths Collection of the Institute of Biology of the National Autonomous University of Mexico. This study is significant because it is the first time that a digenean of the family Brachycoeliidae has been demonstrated to develop in vitro from metacercariae into adults capable of producing eggs using the yolk of unfertilized chicken eggs. Secondly, this technique allows to obtain the adult stage of C. solearis without the presence of its marine turtle host, allows us to describe the mature parasites, and thus contribute to our understanding of the biology of C. solearis.

• Korean Journal of Fisheries and Aquatic Sciences
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• 제24권6호
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• pp.369-396
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• 1991

Nine species of copepod parasites are recorded from nine Korean cultured bivalves. One new species, Lichomolgus similis n. sp. is included, and other eight species are: Conchyliurus quintus, Pseudomyicola spinosus, Myicola ostreae, Ostrincola koe, O. japonica, Herrmannella longicaudata, Modiolicola bifidus, M gracilicaudus. The relationship between the copepod parasites and their host bivalves is discussed.

• Journal of fish pathology
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• 제18권2호
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• pp.119-124
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• 2005

Two species of myxosporean parasites - Parvicapsula anisocaudata and an unidentified myxosporean were found in the lumina of renal tubules and the tubular epithelium, respectively, from cultured olive flounder, Paralichthys olivaceus in Korea. The latter was also seen in interstitial tissue of spleen and interrenal gland of the head kidney. Group of pseudoplasmodia of P. anisocaudata were firmly attached on the epithelium of renal tubules through pseudopodia. In the renal tubule epithelium, a group of unidentified myxosporean trophozoites, which were 2-3 times larger than intraluminal trophozoites of P. anisocaudata, was observed. The parasites being burst out into the lumen was occasionally encountered with partial break of the epithelium. Although infection of P. anisocaudata and unidentified myxosporean parasites did not induce any cellular reaction of the host, occlusion of renal tubules and rupture of renal epithelium would impact negatively on the renal functions of severely infected fish.

• ALGAE
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• 제22권4호
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• pp.287-295
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• 2007

Infection of free-living dinoflagellates by endoparasitic dinoflagellates of the genus Amoebophrya are thought to have significant impacts on host population dynamics and have long been proposed to be a potential biological agent for controlling harmful algal bloom (HAB). To understand the impact of Amoebophrya on particular host species, however, it is necessary to quantify aspects the parasites life cycle. Here we used cultures of Amoebophryahost systems from Jinhae Bay, Korea to determine, parasite generation time, and dinospore survival and infectivity. The proportion of host cells infected by Amoebophrya sp. changed sharply from 5% to 87% with increasing dinospore:host inoculation ratios. In the absence of H. triquetra, most free-living dinospores died within 72 hours and their ability to infect host cells decreased remarkably in a day. The relatively short free-living phase of Amoebophrya suggests that the spread of infections is most likely to occur during seasons of high host abundance, as that is when dinospores have the greatest chance of encountering host cells. Infection of host cells inoculated with dinospores during the day was higher than when inoculated during the night, suggesting that infection rates might be related to environmental light conditions and/or diurnal biological rhythm of host species. Total generation times of parasite strains from a thecate dinoflagellate Heterocapsa triquetra were nearly the same regardless of dinospore:host inoculation ratios, representing 54 ± 0.5 h in a 1:1 ratio and 55 ± 1.2 h in a 20:1 ratio. Dinospore production of Amoebophrya sp. infecting Heterocapsa triquetra was estimated to be 125 dinospores per a strain of Amoebophrya sp. There is a growing need to maintain a variety of host-parasite systems in culture and to examine their autecology under various environmental conditions. Such studies would be very helpful in understanding ecological role of these parasites, their overlooked importance in the flow of material and energy in marine ecosystem, and their practical use as biological control agents applied directly to areas affected by HAB.

• Korean Journal of Agricultural Science
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• 제13권2호
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• pp.176-184
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• 1986

A biological study was done on primary parasites and hyperparasites of green peach aphid, Myzus persicae, collected in Taejeon area during the period from April to September 1985 was. The results of mummification of primary parasites, host selectivity between primary parasites and hyperparasites, and longevity of important species were obtained as follows; 1. Among the 201 mummies collected in the field, adult primary parasites and adult hyperparasites were 38.3% and 44.3%, respectively. 2. Among the primary parasites, Lysiphlebia japonica and Trioxys hokkaidensis were most important species. 3. Among the hyperparasites, Prataphelinus nikalskajae, Eucoila sp. and Ardiles convexa were dominant species. 4. L. japonica was more parasitized by the hyperparasites than T. hokkaidensis. 5. T. hokkaidensis was higher than L. japonica in the ability of parasitism. 6. L. japonica had lived for 3 days by feeding glucose, the other foods had lived shorter than food.

• Molecules and Cells
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• 제26권5호
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• pp.415-426
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• 2008

The interactions between the host and microbial pathogen largely dictate the onset, progression, and outcome of infectious diseases. Pathogens subvert host components to promote their pathogenesis and, among these, cell surface heparan sulfate proteoglycans are exploited by many pathogens for their initial attachment and subsequent cellular entry. The ability to interact with heparan sulfate proteoglycans is widespread among viruses, bacteria, and parasites. Certain pathogens also use heparan sulfate proteoglycans to evade host defense mechanisms. These findings suggest that heparan sulfate proteoglycans are critical in microbial pathogenesis, and that heparan sulfate proteoglycan-pathogen interactions are potential targets for novel prophylactic and therapeutic approaches.

• Parasites, Hosts and Diseases
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• 제38권4호
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• pp.257-261
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• 2000

This study was focused on the effects of microfilament inhibitor, Cytochalasin D (CD) on the invasiveness of sporozoites of Cryptosporidiun spp. into the host cells. MDCK and AGS cell lines were used as host cells for C. parvum and C. muris, respectively. When MDCK cells were pretreated with CD for 1 hr before inoculation of the sporozoites, C. parvum infection was significantly inhibited when compared to the control cells. These inhibitory effects of CD on the rate of infection were dose-dependent. In addition, C. muris infection was hampered when AGS cell lines were pretreated with CD. However, the capability of invasiveness of the sporozoites into the host cells was not greatly influenced by the pretreatment of sporozoites with CD before infection. These results suggest that microfilaments of host cells, rather than parasites, play an important role for the invasion of Cryptosporidium spp.

• The Korean Journal of Malacology
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• 제17권1호
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• pp.57-61
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• 2001

The present study examines the potential involvement of Biomphalaria glabrata, a known molluscan intermediate host of Schistosoma mansoni, in the life cycle of Echinostoma cinetorchis, one of the echinostomes that are ubiquitous parasites of vertebrates and are of importance in human and veterinary medicine and wildlife diseases. Echinostomes can be maintained easily and inexpensively in the laboratory and provide good models for biological research ranging from the molecular to the organismal. In the present study, no echinostome cercariae were released from the B. glabrata experimentally infected with E. cinetorchis miracidia, whereas all the Biomphalaria snails infected with E. cinetorchis cercariae were found to be infected with the metacercariae. This is the first report that B. glabrata can experimentally serve as the second intermediate host of E. cinetorchis, and that it might be employed as one of the target molluscs for establishing a biological research model with E. cinetorchis in the laboratory.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• 제12권2호
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• pp.112-120
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• 2007

This paper reviews the use of parasites as 'biological tags' for studying stock analysis of salmonid fishes. Numerous definitions of stock concepts exist, but most of them essentially define a group of fish as having similar biological characteristics and being self-reproducing as stocks. It is important to manage fish stocks for human consumption and sustainable production and especially for salmonid fishes. Because these fry are considered as each country's property, it is necessary to identify and discriminate each fish stock in the open sea. Methods of separating fish stocks are very diverse. Artificial tags, parasites, otoliths scales and genetic characters have been used for stock analysis and each method has advantages and disadvantages. Of these parasites can be good biological tags because they are applied by nature at no cost. Parasites can be infected with susceptible host fishes when they enter into certain areas. Then if they move to the outside and are caught researchers can infer that the fish had been in the endemic area for a period of time during their life. Hence the host fish can be considered as naturally 'tagged' by parasites. However, if they do not pass the parasites-endemic. area, they will harbour no parasites. Therefore, researchers can discriminate each fish stocks and trace their migration routes with these biological tags. In this paper, several examples on the use of parasites as biological tags for studying salmonids, as well as other species, are listed. The advantages and limitations of parasites as biological tags are also discussed. Chum salmon (Oncorhynchus keta), the main salmonid species migrating to Korea, is distributed all around the North Pacific. Korean chum salmon are generally thought to move to the Sea of Okhotsk, the western North Pacific and the Bering Sea. However, there is no clear information on the distribution and migration pathways of Korean chum salmon, and no markers exist for separating them from others yet. Recent Korean chum salmon stock analysis including parasites information are mentioned.

• Parasites, Hosts and Diseases
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• 제38권1호
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• pp.17-23
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• 2000

Eosinophils are important effector cells in host defense against parasites. Excretory-secretory product (ESP) produced by helminthic worms plays important roles in the uptake of nutrients, migration in the host tissue, and in immune modulation. However little is known about the ability of the ESP to directly trigger eosinophil apoptosis. This study investigated whether the ESP of newly excysted metacercariae of Paragonimus westermani could induce apoptosis in human eosinophils. Apoptosis was assayed by staining the cells with FITC-annexin V, and the cells were analyzed by flow cytometry. It was found that the ESP of newly excysted metacercariae of P. westemani induced a direct time- and concentration-dependent increase in the rate of constitutive apoptosis in mature human eosinophils. Eosinophil apoptosis was first apparent 3 hr after treatment with the ESP and continued to increase after 6 hr of incubation with respect to the cells cultured in the absence of the ESP. While only 2.8% of the eosinophils incubated in the medium for 3 hr were apoptotic, 7.6%, 10.9% and 22.6% of the eosinophils treated with 10. 30 and $100{\;}\mu\textrm{g}/ml$ ESP were apoptotic, respectively. This result suggests that the ESP of newly excysted metacercariae of P. westermani directly induce eosinophil apoptosis, which may be important for the survival of the parasites and the reduction of eosinophilic inflammation in vivo.