• Parasites, Hosts and Diseases
• /
• 제61권4호
• /
• pp.388-396
• /
• 2023

Entamoeba histolytica is an enteric tissue-invasive protozoan parasite causing amoebic colitis and liver abscesses in humans. Amoebic contact with host cells activates intracellular signaling pathways that lead to host cell death via generation of caspase-3, calpain, Ca²⁺ elevation, and reactive oxygen species (ROS). We previously reported that various NADPH oxidases (NOXs) are responsible for ROS-dependent death of various host cells induced by amoeba. In the present study, we investigated the specific NOX isoform involved in ROS-dependent death of hepatocytes induced by amoebas. Co-incubation of hepatoma HepG2 cells with live amoebic trophozoites resulted in remarkably increased DNA fragmentation compared to cells incubated with medium alone. HepG2 cells that adhered to amoebic trophozoites showed strong dichlorodihydrofluorescein diacetate (DCF-DA) fluorescence, suggesting intracellular ROS accumulation within host cells stimulated by amoebic trophozoites. Pretreatment of HepG2 cells with the general NOX inhibitor DPI or NOX2-specific inhibitor GSK 2795039 reduced Entamoeba-induced ROS generation. Similarly, Entamoeba-induced LDH release from HepG2 cells was effectively inhibited by pretreatment with DPI or GSK 2795039. In NOX2-silenced HepG2 cells, Entamoeba-induced LDH release was also significantly inhibited compared with controls. Taken together, the results support an important role of NOX2-derived ROS in hepatocyte death induced by E. histolytica.

• 생태와환경
• /
• 제49권3호
• /
• pp.215-227
• /
• 2016

담수생태계에서 어류기생충의 종류와 감염경로는 다양하고, 중형 또는 고등동물을 숙주로 하여 생활환을 이어가기 때문에 매우 복잡하다. 그중에서 어류의 복강에 기생하는 충류를 대상으로 수행되었다. 본 연구는 2007년 2월부터 10월까지 섬강에서 생긴 피라미의 기생충에 관한 민원을 해결하고자 생태계의 감염특성을 조사하였다. 섬강에서 복강기생충이 관찰된 시기에 감천, 대포천, 양산천 및 율하천도 동일하게 조사하였다. 저서성대형무척추동물은 수서곤충류와 패류가 각각 90.4%, 7.7%로써 주종을 이루었다. 수서곤충류는 하루살이류 (46.8%)와 날도래류 (29.8%)가 대부분을 차지하였고, 패류는 복족류였다. 어류는 잉어과와 피라미 (Zacco platypus)가 각각 85.7%, 48.8%로써 가장 풍부하였다. 물새 조류는 흰뺨검둥오리 (Anas poecilorhyncha)와 쇠백로 (Egretta garzetta)가 높은 밀도로 우점하였다. 어류기생충은 복강에 주로 기생하는 편형동물문 조충류 Ligula intestinalis로써 분류 동정되었다. 10월에 섬강과 양산천에서 우점 서식한 피라미로부터 각각 1개체, 15개체 관찰되었다. 복강기생충의 감염률은 1.4~15.8% 범위였다. 수서생태계의 조사결과로부터 기생충-숙주 관계의 감염 생활사를 고찰하였다. 본 연구결과는 국내의 육수학적 관점에서 복강기생충의 생태를 이해하는 데 유용한 기초자료로써 활용되기를 기대한다.

• 한국식물병리학회:학술대회논문집
• /
• 한국식물병리학회 1994년도 Proceedings of International Symposium on BIOLOGICAL CONTROL OF PLANT DISEASES Korean Society of Plant Pathology
• /
• pp.62-74
• /
• 1994

The current status of the development of commercial products for the biological control of plant-parasitic nematodes is discussed. an example is given of problems encountered by our program in patenting biocontrol agents in the United Stats. Two hypothetical approaches to the control of plant nematodes are considered. First recent experimental results relating to the theory on intervention with host-finding by plant nematodes are reviewed. Second, a newer hypothesis considering the possibilities for genetic approaches to modifying molecular signals between nematodes and their parasites is described.

• 한국수산과학회지
• /
• 제6권3_4호
• /
• pp.112-122
• /
• 1973

붕어와 금붕어에 기생하는 사상충, Philometroides carassii (Ishii, 1931)를 구제할 목적으로 1971년 4월부터 1972년 12월까지 당년어 붕어 200마리와 금붕어 150마리에 이 충의 유충을 여러가지 방법으로 감염시켜, 생활사를 규명하고 약물치료 실험을 하여 다음과 같은 결과를 얻었다. 1. 이 충은 Cyclops sp.가 중간숙주이며 이것의 복강에 침입한 유충은 3시간 이후에 감염력을 가졌다. 2. Cyclops sp.를 경유하지 않고 직접 먹힌 유충은 어체내에서 24시간내 장에서 소화되거나 배설되었다. 3. 중간숙주를 경유하여 어체의 장에 기생한 유충은 $1\~10$일후 복강속으로 침입하고, 여기서 성장하여 미성숙성충이 되었다. 붕어 복강속에서 기생하는 미성숙 성충은 $18\~20$개월 후 꼬리지느러미로 나와 성충이 되었다. 금붕어 복강속에 기생하는 미성숙 성충은 $7\~8$개월 후 꼬리지느러미로 나와 성충이 되었다. 4. 어체 복강속에 기생하는 미성숙 성중에서 본 종의 수컷을 최초로 발견했으며 암컷보다 대형이었다. 5. 성충에 대한 약물 치료효과는 기대할 수 없었고 성충에서 방출되는 유충에 대해 약욕 치료실험한 결과 dipterex가 가장 효과가 있었으며 4ppm으로 5일만에 대부분 폐사되었다.

• Journal of Plant Biology
• /
• 제35권2호
• /
• pp.173-182
• /
• 1992

The parasitic flowering plants obtain nutrients and water from their host plants through a parasitic organ, haustorium, which connects both structurally and physiologically host and parasite. The parasitism in angiosperms thus can be understood from the knowledge of the haustorial structure. The haustoria have evolve convergently and independently in several unrelated taxa; therefore, they have similar morphology. Many anatomical studies on the haustoria in several parasites in the pst have been carried out by light microscopy. Ultrastructural studies on the haustoria, which are started from the end of 1060s', have provided new information relating to the phenomenon of parasitism in angiosperms. The purpose of this paper is to introduce and compare the structure of haustoria between parasitic plants. The results may help an understanding of phylogenetic relationships of parasitic angiosperms. The haustoria of some families, such as Santalaceae, Orobancaceae, Scrophulariaceae, Loranthaceae (or Viscaceae), and Convolvulaceae (Cuscuta) will be discussed.

• Parasites, Hosts and Diseases
• /
• 제37권4호
• /
• pp.197-213
• /
• 1999

Phylogeny is the evolutionary history of a group or the lineage of organisms and is reconstructed based on morphological, molecular and other characteristics. The genealogical relationship of a group of taxa is often expressed as a phylogenetic tree. The difficulty in categorizing the phylogeny is mainly due to the existence of frequent homoplasies that deceive observers. At the present time, cladistic analysis is believed to be one of the most effective methods of reconstructing a phylogenetic tree. Excellent computer program software for phylogenetic analysis is available. As an example, cladistic analysis was applied for nematode genera of the family Acuariidae, and the phylogenetic tree formed was compared with the system used currently. Nematodes in the genera Nippostrongylus and Heligmonoides were also analyzed, and the validity of the reconstructed phylogenetic trees was observed from a zoogeographical point of view. Some of the theories of parasite evolution were briefly reviewed as well. Coevolution of parasites and humans was discussed with special reference to the evolutionary relationship between Enterobius and primates.

• Parasites, Hosts and Diseases
• /
• 제47권2호
• /
• pp.171-174
• /
• 2009

The antigen location of Cryptosporidium parvum, which stimulates antibody formation in humans and animals, was investigated using infected human sera. Immuno-electron microscopy revealed that antigenicity-inducing humoral immunity was located at various developmental stages of parasites, including asexual, sexual stages, and oocysts. The amount of antigen-stimulating IgG antibodies was particularly high on the oocyst wall. The sporozoite surface was shown to give stimulation on IgG and IgM antibody formation. Trophozoites implicated the lowest antigenicity to humoral immunity, both IgG and IgM, by showing the least amount of gold labeling. Immunogold labeling also provided clues that antigens were presented to the host-cell cytoplasm via feeder organelles and host-parasite junctions.

• Parasites, Hosts and Diseases
• /
• 제61권3호
• /
• pp.325-331
• /
• 2023

Thelazia callipaeda, a parasitic nematode that causes thelaziosis in various mammals, including humans, is known to be endemic in Korea. However, life cycle-related information on the parasite, primarily from human infection and a few dog cases, is limited. This study reports additional cases of T. callipaeda infections in dogs from both rural and urban areas in Korea, indicating the potential for transmission to humans and other animals. We collected 61 worms from 8 infected dogs from Paju and Cheongju Cities and observed their morphological characteristics under a light microscope. The findings indicate that T. callipaeda infections in animals in Korea may be underestimated and are distributed close to human environments. Our results contribute to the growing knowledge of the reservoir hosts of T. callipaeda in Korea and highlight the importance of continued surveillance and research to prevent and control this emerging zoonotic disease.

• 대한산업공학회지
• /
• 제27권3호
• /
• pp.239-249
• /
• 2001

Competitive coevolution models, often called host-parasite models, are searching models that imitate the biological coevolution that is a series of reciprocal changes in two competing species. The models are known to be an effective method of solving complex and dynamic problems such as game problems, neural network design problems and constraint satisfaction problems. However, previous models consider only ectoparasites that live on the outside of the host when designing the models, not considering endoparasites that live on the inside of the host. This has a limitation to exploiting some information. In this paper, we develop an artificial adaptation model simulating the process in which hosts coevolve with both ectoparasites and endoparasites. In the model, the endoparasites play important roles as follows. By means of them, we can keep the history on results of previous competition between hosts and parasites, and use endogeneous fitness, not exogeneous. Extensive experiments are carried out to show the coevolution phenomenon and to verify the performance of the proposed model. Nim game problems and neural network problems are used as test-bed problems. The results are reported in this paper.

• 농업과학연구
• /
• 제12권2호
• /
• pp.253-259
• /
• 1985

수도(水稻)의 주요해충(主要害蟲)인 멸구매미충류의 천적(天敵)과 이들의 기주범위(寄主範圍)에 대한 선호성(選好性)을 조사(調査)하여 다음과 같은 결과(結果)를 얻었다. 1. 멸구매미충류에 기생(寄生)하는 주요천적(主要天敵)으로서 Anagus nr. flaveolus, Gonatocerus sp., Haplogonatopus atratus, Elenchus japonicus, Eudorylas, sp.등이었는데 이들은 대부분(大部分)의 멸구매미충에 모두 기생(寄生)하고 있었으며 특히 A.nr. flaveolus는 난기생봉(卵寄生蜂)으로서, Haplogonatopus atratus는 약충(若蟲) 기생천적(寄生天敵)으로서 애멸구의 주요천적(主要天敵)으로서 밝혀졌으며, Gonatocerus sp.는 끝동매미충의 중요(重要)한 난기생천적(卵寄生天敵)으로서, Eudorylas sp.는 반듯이 끝동매미충의 약충(若蟲)이나 성충(成蟲)에만 기생(寄生)하는 종(種)임을 알 수 있었다. 2. 포식성(捕食性) 천적(天敵)으로는 Nabis ferus, Cytorhinus lividipennis와 Mortonagrion selenion을 비롯한 실잠자리류(類) 그리고 Pirata subpiraticus 와 G-nathonarium dentatum 둥의 거미들이 있으며 N. ferus는 애멸구 약충(若蟲)에 C. lividipennis는 벼멸구의 포식천적(捕食天敵)으로서 유력(有力)한 종(種)이며 M. selenion과 p subpiraticus와 G. dentatum은 여러종류의 멸구매미충을 골고루 포식(捕食)하고 있었다. 3. 곤충(昆蟲) 병원균(病原菌)으로서 Entomophthora sp.는 각종 멸구매미충(蟲)에서 쉽게 볼 수 있었으며 Agamermis unka는 벼멸구에 기생(寄生)하는 녹충(綠蟲)으로서 지역(地域)이나 해에 따라서 많은 차이(差異)를 볼 수 있었다. 4. 멸구매미충류(蟲類)의 포식(捕食)논거미 중(中)에서 Pirata subpiraticus가 가장 유력(有力)한 종(種)으로서 알려졌으며 애멸구를 가장 선호(選好)하는 것으로 나타났다. 한펀 약충(若蟲)과 성충(成蟲)의 생육단계(生育段階)에 따른 먹이 선택성(選擇性) 실험결과(實驗結果) 성충(成蟲)보다는 약충(若蟲)을 뎌욱 선호(選好)하는 것으로 밝혀졌다.