• Journal of Microbiology and Biotechnology
• /
• 제18권5호
• /
• pp.852-858
• /
• 2008

An extracellular protease (Mc1) was isolated from the nematode-trapping fungus Monacrosporium cystosporium by gel filtration, anion-exchange, and hydrophobic interaction chromatographies. This protease had a molecular mass of approximately 38 kDa and displayed an optimal activity at pH 7-9 and $56^{\circ}C$ (over 30 min). Its proteolytic activity was highly sensitive to the serine protease inhibitor PMSF (phenylmethylsulfonylfluoride, 0.1 mM), indicating that it belonged to the serine-type peptidase group. The Michaelis constant ($K_m$) and $V_max$ for substrate N-Suc-Ala-Ala-Pro-Phe-pNA were $1.67{\times}10^{-4}\;M$ and 0.6071 $OD_{410}$ per 30 s, respectively. This protease could degrade a broad range of substrates including casein, gelatin, BSA (bovine serum albumin), and nematode cuticle. Moreover, the enzyme could immobilize the free-living nematode Panagrellus redivivus and the pine wood nematode Bursaphelenchus xylophilus, suggesting that it might playa role in infection against nematodes. The encoding gene of Mc1 was composed of one intron and two exons, coding for a polypeptide of 405 amino acid residues. The deduced amino acid sequence of Mcl showed 61.4-91.9% identity to serine proteases from other nematode-trapping fungi. Our results identified that Mcl possessed biochemical properties including optimal reaction condition and substrate preference that are different from previously identified serine proteases.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제6권4호
• /
• pp.252-263
• /
• 2001

Nematode infections compromise human health and reduce agricultural productivtiy. Experiments that exploit the powerful molecular genetics of the free-living nematode Caenorhabdl - elegans have contributed to our understanding of how the major classes of anthelmintic nema-tocides kill worms and how worms might evolve resistance to these drugs In C. elegans, as in parasites, benzimidixoles interfere with microtubule polyumerization the imidazothiazoles/tetra-hydropyrimidines activate nicotinic acetylcholine receptors, and the macrocyclic la ctones activate qlutamate-gate chloride chanels. Mutant alleles of genes that encode drug targes often confer resistance in C. elegans. Preliminary evidence suggests that alleles of homologous genes in parasites will, in many cases, also play a role in resistance. Thus information acquired from C. elegans can be usefully applied to understand the mechanisms of drug sensitivity and the genetics of resis-tance in parasites.

• Ocean Science Journal
• /
• 제41권3호
• /
• pp.163-173
• /
• 2006

A draconematid nematode species, Dracograllus filipjevi Allen and Noffsinger, 1978, is described from the washings of shallow littoral coralline algae at Guryongpo in the eastern coast of Korea. This species is recognized by the following characteristics: larger body size, number of posterior sublateral adhesion tubes (9 in male and 12-13 in female) and subventral adhesion tubes (8-9 in male and 9-10 in female), the absence of cephalic acanthiform setae on rostrum, the presence of longitudinally areolated body cuticle with dot-like punctations, the presence of some cuticular collar in swollen pharyngeal region, the shape of amphidial fovea (large, elongate, and loop-shaped in both sexes), the absence of preanal corniform setae, and the absence of lateral differentiation on narrow body region. Morphological features of the species using differential interference contrast photomicrographs are described in detail in the present work. The is the first report of D. filipjevi in Korea.

• 한국환경독성학회:학술대회논문집
• /
• 한국환경독성학회 2003년도 춘계학술대회
• /
• pp.146-147
• /
• 2003

The free-living nematode, Caenorhabditis elegans (C. elegans) has been adopted as a multicellular biosensor of biological toxicity for alkylphenol, organotin compounds and heavy metals. To adopt as a biosensor, suitability to assess must be fulfilledthrough several criteria; the organism must be sensitive to the testing toxicants, easy to manage in the laboratory and available throughout the year. C. elegans widely used as a simple multicellular organism in developmental biology studies and satisfies all these criteria, and its culture conditions, developmental staging, anatomy and genetic properties are well defined. In addition, researchers can take advantage of the worm's short life cycle, low cost and little individual variation. Moreover, genomic sequencing of C. elegans has recently been completed. With these aspectsof the organism, C. elegans become a more potent model organism for basic and applied bioassays.

• Environmental Analysis Health and Toxicology
• /
• 제21권3호
• /
• pp.239-244
• /
• 2006

Caenorhabditis elegans(C. elegans) is a free-living soil nematode that commonly used as a biological model and recently, much work has been done using C. elegans as a toxicity model. To evaluate the acute toxicity of phenols to C. elegans, worms were subsequently exposed to nine different xenobiotics. This study described lethal toxicity, reproductive toxicity and movement inhibition using 2-propylphenol, 4-propylphenol, 2-tert-butylphenol, 3-tert-butylphenol, 4-tert-butylphenol, 2-phenylphenol, 4-phenylphenol, nonylphenol and 4-dodecylphenol to C. elegans for 24 hr or 72 hr. We found that phenols used in this study were very toxic to C. elegans. The order of lethal toxicity, reproductive toxicity and movement inhibition is as follows. 4-propylphenol > 2-phenylphenol > 2-tert-butylphenol > 2-propylphenol > nonylphenol > B-tert-butylphenol > 4-dodefylphenol > 4-tert-butylphenol > 4-phenylphenol.

• Animal Systematics, Evolution and Diversity
• /
• 제24권2호
• /
• pp.199-203
• /
• 2008

Desmotimmia mirabilis (Timm), a rarely known desmoscolecid nematode species, was discovered for the first time from the Yellow Sea off southwestern coast of Korea. This is the third record of the species, and the first report from the northwestern Pacific region. Redescription is prepared on the basis of a male specimen from South Korea.

• 대한수의학회지
• /
• 제30권4호
• /
• pp.499-505
• /
• 1990

The seasonal availability and abundance of the free-living stages of sheep nematodes is a key factor in the occurrence and severity of parasitic infection, and studies of larvae ecology could result in more rational control measures. In the present study seasonal pasture contamination and availability of nematodes for grazing sheep was examined as a baseline work for nematode control program at Namwon Branch, National Animal Breeding Institute during the period April 1988 through March 1989. Standard meteorological measurements were available from Unbong Sub-station, Honam Crops Experiment Station located about 200m from the experimental site. A total of 5 kinds of nematode larvae was detected: Haemonchus contortus was most prevalent (38.0%) with a decreasing order of Ostertagia spp (35.1%), Trichostrongylus spp (19.8%), nematodirus spp (6.6%), and Oesophagostomum spp (0.5%). A succession of species was recorded, in particular Ostertagia spp in May; Haemonchus contortus in June and July; Trichostrongylus spp in July and August; Nematodirus spp in August and September. These results can be incorporated into the nematode control program. To make a more rational control program, however, repeated herbage larval counts should be undertaken soil larval counts and fecal larval counts in the future.

• 환경생물
• /
• 제40권4호
• /
• pp.477-496
• /
• 2022

During a survey of free-living marine nematodes of Korea, two new marine desmoscolecid nematodes belonging to subgenus Quadricoma Filipjev, 1922 were discovered. Tricoma (Q.) jejuensis sp. nov. and T.(Q.) unipapillata sp. nov. are described based on specimens obtained from washings of coarse sediments from eastern and southern coasts of Korea. Tricoma (Q.) jejuensis sp. nov. is characterized by having 33 quadricomoid body rings and inversion at main ring 23, pentagonal head with truncated anterior end, a pair of ocelli situated at main ring 6, somatic setae comprising of 8 pairs of subdorsal setae and 12 pairs of subventral setae, and relatively short spicules (42-46 ㎛ long). Tricoma (Q.) unipapillata sp. nov. is characterized by 44 quadricomoid body rings and inversion at main ring 32, somatic setae comprising of 7 pairs of subdorsal setae and 10 pairs of subventral setae, globular head truncated anterior end, relatively short and stumpy cephalic setae with cuticular flange, one single naked ventral median genital papillae situated on main ring 20, and spicules with a proximally marked capitulum. Detailed morphological descriptions and illustrations of these two new species are provided in this study.

• Journal of Species Research
• /
• 제13권2호
• /
• pp.147-158
• /
• 2024

Four species of the free-living nematodes were collected from marine sediments in the sublittoral zone in the East Sea, Korea and were identified, described, and illustrated. Paranticoma tricerviseta Zhang, 2005, originally described from the Bohai Sea, China, is recorded for the first time in the East Sea, Korea; only in body length and thickness (1902-2282 ㎛ compared to 2472-3300 ㎛, 50-62 ㎛ compared to 57-82 ㎛, respectively). Specimens of Parodontophora marina Zhang, 1991, from East Sea, Korea largely agrees with the original description of Zhang (1991) of nematodes from the Bohai Sea, except for differences in body length and thickness (1190-1345 ㎛ compared to 1235-1408 ㎛, 40-44 ㎛ compared to 42-72 ㎛). Terschellingia longicaudata de Man, 1907 is reported for the first time in Korea, but was previously considered a cosmopolitan species of nematodes with a widespread distribution from the North Sea, Belgium to the Exclusive Economic Zone of New Zealand; it differs from the original description in body thickness(30-38 ㎛ vs. 40-62 ㎛). Vasostoma brevispicula Huang & Wu, 2011, originally described from the subtidal muddy sediment in the Yellow Sea, China, is newly reported in Korea; apart from a few minor morphological differences, body length and thickness (2009-2425 ㎛ vs. 2119-2906 ㎛, 41-48 ㎛ vs. 37-58 ㎛). The present study on unrecorded species improves our understanding of nematode species diversity in Korean waters.

• Ocean Science Journal
• /
• 제42권3호
• /
• pp.135-152
• /
• 2007

The ecological aspect of meiofaunal communities in Can Gio mangrove forest, Ho Chi Minh city, Vietnam has not been investigated before. The composition, distribution, density and biodiversity of meiofaunal communities were studied along an intertidal transect at the Khe Nhan mudflat. Each time, three replicate samples were collected in four stations along a transect following the water line from low tide level up to the mangrove forest edge. In total, 18 meiofaunal taxa were found with the dominant taxa belonging to Nematoda, Copepoda, Sarcomastigophora and Polychaeta. The densities of meiofauna ranged from $1156inds/10cm^2$ to $2082inds/10cm^2$. The increase in densities from the mangrove forest edge towards the low water line was significant Along the mudflat transect, the biodiversity (expressed by different indices) was relatively high at different taxonomic levels but did not vary significantly along the mudflat except for taxa richness. Eighty nematode genera belonging to 24 families with Comesomatidae having the highest abundance 33.8 % were found. Theristus and Neochromadora decreased in densities from the lower water line towards the mangrove forest edge, while Paracomesoma and Hopperia are typical and more abundant at the middle of the mudflat. Halalaimus increased from high on the mudflat to the low water line.