• Journal of Ecology and Environment
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• 제44권2호
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• pp.81-89
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• 2020

In the forest ecosystems, litterfall is an important component of the nutrient cycle that regulates the accumulation of soil organic matter (SOM), the input and output of the nutrients, nutrient replenishment, biodiversity conservation, and other ecosystem functions. Therefore, a profound understanding of the major processes (litterfall production and its decomposition rate) in the cycle is vital for sustainable forest management (SFM). Despite these facts, there is still a limited knowledge in tropical forest ecosystems, and further researches are highly needed. This shortfall of research-based knowledge, especially in tropical forest ecosystems, may be a contributing factor to the lack of understanding of the role of plant litter in the forest ecosystem function for sustainable forest management, particularly in the tropical forest landscapes. Therefore, in this paper, I review the role of plant litter in tropical forest ecosystems with the aims of assessing the importance of plant litter in forest ecosystems for the biogeochemical cycle. Then, the major factors that affect the plant litter production and decomposition were identified, which could direct and contribute to future research. The small set of studies reviewed in this paper demonstrated the potential of plant litter to improve the biogeochemical cycle and nutrients in the forest ecosystems. However, further researches are needed particularly on the effect of species, forest structures, seasons, and climate factors on the plant litter production and decomposition in various types of forest ecosystems.

• Journal of the Korean Wood Science and Technology
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• 제50권1호
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• pp.46-58
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• 2022

Wood from tropical plantation forests has lower physical and mechanical properties than mature wood. Furfuryl alcohol (FA) impregnation into the wood could help to enhance hydrophobic properties, dimensional stability, and structural strength. Furfurylation was applied to specimens of the following four fast-growing tropical wood species: jabon (Anthocephalus cadamba), sengon (Falcataria moluccana), mangium (Acacia mangium), and pine (Pinus merkusii). The discoloration and physical and mechanical properties were subsequently measured, and the results showed that furfurylated wood had a darker color and better physical and mechanical properties than untreated wood. Specifically, the furfurylated wood had higher density, modulus of elasticity, and hardness and lower moisture content, water absorption, swelling, and shrinkage. The furfurylation significantly enhanced physical and mechanical properties.

• Parasites, Hosts and Diseases
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• 제58권3호
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• pp.327-331
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• 2020

Toxoplasma gondii are intracellular protozoa that can cause neurological disease or death in fetuses and even in immunocompromised human adults. Ticks are recognized as vectors of many microorganisms including viruses, bacteria, and protozoa. Recent studies detected T. gondii in various tick species in many countries. In this study, we performed PCR detection of the T. gondii B1 gene from Haemaphysalis ticks collected from vegetation in 4 localities, Wonju, Gunsan, Miryang, and Yangsan, in Korea. We analyzed DNA from 314 ticks (268 Haemaphysalis longicornis and 46 Haemaphysalis flava) and the B1 gene of T. gondii was detected in 13 of these. The detection of T. gondii in ticks differed significantly by region (P=0.021). T. gondii was detected in the following percentages of collected ticks: 3.7% (7 of 189) in Gunsan, 10% (5 of 50) in Wonju, 16.7% (1 of 6) in Yangsan, and 0% (0 of 69) in Miryang. The detection of T. gondii in ticks was not associated with tick species or development stage. This is the first report of T. gondii detection in ticks in Korea. Our results provide important information necessary to understand toxoplasmosis transmission.

• Parasites, Hosts and Diseases
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• 제57권3호
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• pp.313-318
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• 2019

In recent years, the taeniasis has been rarely reported in the Republic of Korea (Korea). But in this study, we intend to report 4 taeniasis cases caused by Taenia saginata during a 5-month period (February to June 2018) at a unversity hospital in Gwangju, Korea. Worm samples (proglottids) discharged from all cases were identified by phenotypic and molecular diagnostics. Mitochondrial cytochrome c oxidase subunit I sequences showed 99.4-99.9% identity with T. saginata but, differed by 4% from T. asiatica and by 7% from T. multiceps, respectively. We found that tapeworms in 2 cases (Cases 2 and 3) yielded exactly the same sequences between them, which differed from those in Cases 1 and 4, suggesting intra-species variation in tapeworms. These taeniasis cases by T. saginata infection in this study, which occurred within a limited time period and region, suggest the possibility of a mini-outbreak. This study highlights the need for further epidemiological investigation of potentially overlooked cases of T. saginata infection in Korea.

• Parasites, Hosts and Diseases
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• 제62권3호
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• pp.270-280
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• 2024

Trichomoniasis is caused by a sexually transmitted flagellate protozoan parasite Trichomonas vaginalis. T. vaginalis-derived secretory products (TvSP) contain lipid mediators such as leukotriene B₄ (LTB₄) and various cysteinyl leukotrienes (CysLTs) which included LTC₄, LTD₄, and LTE₄. However, the signaling mechanisms by which T. vaginalis-induced CysLTs stimulate interleukin (IL)-8 production in human mast cells remain unclear. In this study, we investigated these mechanisms in human mast cells (HMC-1). Stimulation with TvSP resulted in increased intracellular reactive oxygen species (ROS) generation and NADPH oxidase 2 (NOX2) activation compared to unstimulated cells. Pre-treatment with NOX2 inhibitors such as diphenyleneiodonium chloride (DPI) or apocynin significantly reduced ROS production in TvSP-stimulated HMC-1 cells. Additionally, TvSP stimulation increased NOX2 protein expression and the translocation of p47^phox from the cytosol to the membrane. Pretreatment of HMC-1 cells with PI3K or PKC inhibitors reduced TvSP-induced p47^phox translocation and ROS generation. Furthermore, NOX2 inhibitors or NOX2 siRNA prevented CREB phosphorylation and IL-8 gene expression or protein secretion induced by TvSP. Pretreatment with a CysLTR antagonist significantly inhibited TvSP-induced ROS production, CREB phosphorylation, and IL-8 production. These results indicate that CysLT-mediated activation of NOX2 plays a crucial role in ROS-dependent IL-8 production in human mast cells stimulated by T. vaginalis-secreted CysLTs. These findings enhance our understanding of the inflammatory response in trichomoniasis and may inform the development of targeted therapies to mitigate this response.

• Parasites, Hosts and Diseases
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• 제42권1호
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• pp.41-44
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• 2004

The pond smelt Hypomesus olidus and minnow Zacco platypus were collected from the Soyang and Daechung Lakes in January 2003, and their metacercarial infections was examined by the muscle compression and artificial digestion techniques. In the Soyang Lake, 161 metacercariae of Clonorchis sinensis (0.35 per fish) were harvested from 459 pond smelts examined. Also, 13 metacercariae of C. sinensis (0.43 per fish), 1 of Metagonimus sp., 4 of Echinostoma sp., 148 of Centrocestus armatus and 44 unidentified species were collected from 30 minnows. In the Daechung Lake, 369 metacercariae of C. sinensis (3.69 per fish) and 51 unidentified species were recovered from 100 pond smelts. The metacercariae of C. sinensis were fed to experimental rats, in which the adult flukes were identified. The pond smelts and minnows collected from the Soyang and Daechung Lakes were verified to be the second intermediate hosts and the sources of human C. sinensis infection.

• Animal Systematics, Evolution and Diversity
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• 제23권2호
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• pp.109-115
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• 2007

Eight species of Chironomidae (Diptera) which are new to Korea are described with illustrations. They are extremely rare species in Korea, as only one or two specimens have been collected since 1977 throughout the country. Microchironomus tener, Stictochironomus akizukii and Paratendipes nubilus belong to subfamily Chironominae, and the other five species: Diplocladius cultriger, Limnophyes minimus, Metriocnemus fulvofasciatus and Parametriocnemus stylatus belong to subfamily Orthocladiinae.

• 한국산림과학회지
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• 제97권2호
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• pp.171-180
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• 2008

The characterization of tree species and forest stand conditions is useful in the planning of activities aimed to conserve biodiversity. The main objective of this study was to describe tree species diversity, species composition and stand structure of tropical deciduous forests distributed in three regions in Myanmar. Forest inventory was conducted in the Oktwin teak bearing forest, the Letpanpin community forest and Alaungdaw Kathapa National Park. According to the Jackknife estimator of species richness, 85 species (${\pm}18.16$), 70 species (${\pm}5.88$) and 186 species (${\pm}17.10$) belonging to 31 families were found in the Oktwin teak bearing forest, 33 families in Letpanpin community forest and 53 families in Alaungdaw Kathapa national park, respectively. Shannon's diversity indices were significantly different among the forests (p<0.05). It ranged from 3.36 to 4.36. Mean tree density (n/ha) of the Oktwin teak bearing forest, Letpanpin community forest and Alaungdaw Kathapa National Park were 488 (${\pm}18.6$), 535 (${\pm}15.6$) and 412 (${\pm}14.1$), while basal areas per hectare were $46.96m^2({\pm}3.23),\;49.01m^2({\pm}5.08)\;and\;60.03m^2({\pm}3.88)$, respectively. At the family level, Verbenaceae, Myrtaceae and Combretaceae occupied the highest importance value index, while at the species level it was Tectona grandis, Lagerstoremia speciosa and Xylia xylocarpa.

• Parasites, Hosts and Diseases
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• 제56권5호
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• pp.501-507
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• 2018

We described here the morphological characteristics for the species identification and fish hosts of Isoparorchis sp. (Digenea: Isoparorchiidae) in the Republic of Korea (Korea). Total 1,371 freshwater fishes collected in Yangcheon (Stream) in Sancheong-gun, Gyeongsangnam-do were examined by the artificial digestion methods to survey the infection status of digenetic trematode metacercariae for 4 years (2013-2016). Adult and larval worms of Isoparorchis sp. were detected in 38 (8.4%) out of 451 fish in 4 species, i.e., Pungtungia herzi, Acheilognathus koreensis, Squalidus japonicus coreanus and Odontobutis platycephala, examined. The infection density was 1.1 worm per fish infected. They were mainly found in the subcutaneous tissues and abdominal cavities. Nodules with worms in the subcutaneous tissues were revealed as the blue ink-colored bulges. Adults leaf-like, $21.6{\times}9.84mm$ in average size. The ratio of body length to body width was 2.20: 1. Oral sucker subterminal, $1.03{\times}1.22mm$. Pharynx muscular, $0.55{\times}0.54mm$. Esophagus very short. Ceca convoluted, terminated near the posterior end. Ventral sucker anterior 1/3.75, $1.99{\times}2.10mm$. The ratio of ventral sucker to oral sucker was 1.74: 1. Testes round to elliptical, both sides of ventral sucker, $1.43{\times}1.33mm$. Vitellaria highly dendritic, posterior 1/3 level. Eggs operculated, embryonated, $52{\times}32{\mu}m$ in size. By the present study, 4 fish species aforementioned are to be listed as the fish hosts of Isoparorchis sp. in Korea and additionally the morphological characteristics are to be described for the species identification.

• 농촌의학ㆍ지역보건
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• 제15권2호
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• pp.107-111
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• 1990

A survey was undertaken to evaluate the present status of intestinal infection in army soldiers. Stool specimen of 417 soldiers fixed by SAF solution were collected from a camp located in area of Nakdong river during the period from August to October of 1990. And these stool samples were examined by formalin-ether sedimentation technique once for helminths and protozoan cysts stained with Lugol's iodine solution. The results obtained in this survey were summarized as follows : l) The overall positive rate of intestinal parasite was 18.0%. 2) The egg positive rate of intestinal helminth was 15.1%, : and 11.5% for Clonorchis sinensis. 5.0% for Metagonimus vokogawai, 1.2% for Ascaris lumbricoides 1.7% for Trichiuris trichiura. 0.2% for Taenia sp. 3) The cyst positive rate of intestinal protozoa was 4.1% ; and 1.4% for Entamoeba coli, 1.9% for Giardia lamblia 0.7% for Entamoeba histolytica, 0.5% for Endolimax nana. 4) Most of samples were positive(85.3%) by single species. 10.7% by two species, 2.7% by three species and 1.3% by four species. 5) Infection rate of intestinal parasites among army soldiers decreased distinctly compared with previous data but it is revealed that the infection rate of Clonorchis sinensis among army soldiers in area of Nakdong river is still high in comparison with ever-reported data. 6) SAF fixatives used in this field survey during summertime was useful to conserve protozoan cyst and helminths ova. Also we could examine stool samples directly by formalin-ether sedimentation technique.