• Animal cells and systems
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• v.10 no.4
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• pp.219-225
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• 2006

As a result of the faunistic survey of the free-living marine nematodes from coastal algal beds and sublittoral sands in South Korea, we report a meiobenthic species, Desmoscolex cosmopolites Timm, 1970, for the first time from the western Pacific as well as Korean waters. Among 17-ring Desmoscolex species, D. cosmopolites is represented by the following combination of characters: absence of subventral setae on 10th and 14th main rings and the presence of subdorsal setae with large angular lance-shaped tip. A detailed morphological redescription is provided using a scanning electron microscope and a differential interference contrast microscope. Character comparison between D. cosmopolites and its allied congeneric species is also analysed.

• Archives of Pharmacal Research
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• v.28 no.8
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• pp.897-901
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• 2005

The in vitro inhibitory activities of essential oils from Thymus magnus and T. quinquecostatus as well as their main constituents were evaluated against susceptible and resistant species of Streptococcus pneumoniae, Staphylococcus aureus, Salmonella enteritidis, and Salmonella typhimurium. Notably, the essential oil fraction of T. magnus and its main components displayed significant inhibitory action against both antibiotic-susceptible and resistant strains of S. pneumoniae, S. aureus, and S. typhimurium with minimum inhibitory concentrations (MICs) ranging from 0.125 to 8 mg/mL. The differential MIC values imply that the oil fraction and its main components exhibit distinct patterns of activity against the tested bacterial species. Moreover, the disk diffusion test revealed that the inhibitory activities of oil fraction and components were dose-dependent. Data from the checkerboard titer test confirmed synergism between the antibiotic, norfloxacin, and T. magnus oil or thymol, particularly against the resistant strains of S. aureus.

• Korean Journal of Environmental Biology
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• v.39 no.4
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• pp.463-470
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• 2021

Admirandus multicavus Belogurov and Belogurova, 1979, a new record of free-living marine nematode species belonging to family Oncholaimidae is reported based on the specimens collected from the intertidal sediments of Korea. Admirandus multicavus is characterized by the following unique characteristics: cephalic setae (1-2 ㎛ long), spicules (71-126 ㎛ long) and gubernaculum (15-31 ㎛ long), midventral preanal supplementary organ, three glandular duct openings of the Demanian system, and stoma length measuring twice the width. A comparative analysis of the biogeographical and ecological characteristics of Admirandus species is presented. DIC (Differential interference contrast) photomicrographs of the species are also provided herein. This report represents the first taxonomic analysis of the genus Admirandus Belogurov and Belogurova, 1979 discovered from the Korean seawaters.

• Korean Journal of Environmental Agriculture
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• v.15 no.3
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• pp.316-324
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• 1996

The four tolerant and one susceptible plant to oxyfluorfen were selected from 26 species and investigated for the inhibition of protox activity, the PPIX accumulation, and the activity of antioxidative enzymes by oxyfluorfen treatment. When treated, the oxyfluorfen-tolerant plant species showed a less decrease in fresh weight and height than the susceptible one. The susceptible barnyardgrass showed more inhibition of protox activity due to the treatment of oxyfluorfen than the tolerant species. Especially at the concentration of $10^{-6}M$, protox activity of the susceptible barnyardgrass was inhibited completely, but tolerant species maintained $25{\sim}45%$ of the activity. Under the light and dark condition, the susceptible barnyardgrass showed more PPIX accumulation than the tolerant.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.4
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• pp.356-361
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• 2006

The present study was conducted to determine plant growth and physiological responses of corn, barnyardgrass, and soybean to ALA (5-aminolevulinic acid). ALA effect on early seedling growth of test plants was greatly concentration dependant, suggesting that it inhibits at higher concentrations. No significant difference in herbicidal activity of two types of ALA on plant height and weight of test plants was observed. Barnyardgrass was the most sensitive to ALA and followed by corn and soybean, indicating that both crop plants were less affected by ALA concentration as well as different growth stages than barnyardgrass. Greatly reduced chlorophyll contents from leaves of three plant species were observed with increasing of ALA concentration. Compared with untreated controls, higher amounts of three tetrapyrroles were detected from three crop plants, indicating more accumulation in ALA-treated plants. The differential selectivity among plant species would be explained with the differences in tetrapyrrole accumulating capabilities, the susceptibility of various greening groups of plant species to the accumulation of various tetrapyrroles, and their metabolism in various plant tissues. The results indicate that negative biological potential of ALA exhibited differently on plant species, and that the photodynamic herbicidal activity against susceptible plants highly correlated with the extent of tetrapyrrole accumulation by the species.

• Animal cells and systems
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• v.15 no.1
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• pp.85-90
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• 2011

In 2001, we conducted a study to assess the effects of differential arrival times and nest-site selection on reproductive performance in a mixed-species heronry consisting of six species in Taeseong-ri, Chungbuk, Korea. We recorded the arrival dates, nest heights, clutch sizes, and brood sizes after 15-20 days of the age of the birds' chicks. The grey herons and cattle egrets arrived first and last, respectively, on the colony site. In the homogenous vegetation structure of the breeding site, the pitch pine trees (Pinus rigida) were mainly used for building nests on 48 of the 50 pine trees (96%). The breeding species vertically stratifies the nest sites according to their body size, except for the cattle egrets and black-crowned night herons that nested at sites higher than those predicted from their body size. The mean nest success rates of the six species under study were positively correlated with the mean nest heights. Our findings suggest that aggressive interspecific interactions among neighbors influence nest-site selection to enhance breeding success.

• Korean Journal of Veterinary Research
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• v.41 no.4
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• pp.535-542
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• 2001

A multiplex PCR technique was developed for detecting specifically each Mycobacterium bovis, M. tuberculosis, M. avium and M. avium subsp, paratuberculosis, respectively, using clinical samples of field cattle. To apply this novel technique to clinical specimens, blood sample was obtained from live cows comprising 11 intradermal tuberculin test (ITT)-positive and 17 ITT-negative and tested by multiplex PCR. Positive results were obtained from 15 cows by the multiplex PCR, showing that 4 (23.5%) of the 17 ITT-negative cows were multiplex PCR positive. The multiplex PCR results also showed that among the 15 positive cows, 7 (46.7%) were infected with M. bovis, 1 (6.7%) with M. tuberculosis and 7 (46.7%) with M. avium. The sensitivity and specificity of multiplex PCR in comparison with those of ITT were 100% and 76.5%. The correlation between the multiplex PCR and ITT assays with blood samples was considered excellent, 85.7% agreement and ${\kappa}=0.72$. The results obtained, using reference mycobacterial strains and typed clinical samples, show that the multiplex PCR method may be a rapid, sensitive, and specific tool for the differential identification of various mycobacterial strains in a single-step assay. Therefore, multiplex PCR assay is a useful tool for early diagnosis of tuberculosis in live cattle and to identify the species or complex of mycobacterium from clinical samples.

• Parasites, Hosts and Diseases
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• v.55 no.3
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• pp.287-294
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• 2017

The present study was performed to record new definitive hosts of Isthmiophora hortensis, and to describe morphological characteristics derived from a variety of worm samples for clarification of its taxonomic validity. Morphological characteristics with dimensions were observed in worm samples (n=21) from naturally infected wild animals, including a raccoon dog Nyctereutes procyonoides from Gimhae-si (City), Gyeongsangnam-do, stray cats and a striped field mouse from several localities, and a wild boar Sus scrofa, from Gurye-gun (County), Jeollanam-do. In addition, adult flukes (n=45) recovered in albino rats experimentally infected with the metacercariae from a freshwater fish species were also subjected to morphological studies. The mean ratios of the body length (BL) to body width (BW) were 5.86 and 5.76 in worms from wild animals and experimental rats, respectively. Those of the ventral sucker to oral sucker were 2.92 and 3.01 in worms from 2 groups. The mean percentages of the hindbody length (HBL) to BL were 42.1 and 41.2 in 2 groups. Those of uterine fields to BL were 9.8 and 12.2 in the 2 worm groups. By the present study, the 2 species of wild animals, the raccoon dog and wild boar, have been added as new definitive hosts for I. hortensis. The morphological characteristics of adult flukes derived from a variety of host source were redescribed to support the taxonomic validity of this echinostome species.

• Journal for History of Mathematics
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• v.24 no.2
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• pp.47-59
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• 2011

Various mathematical models have been widely studied recently in both fields of mathematics and ecology since they help us understand the dynamical process of population changes in biological species living in a certain habitat and give useful predictions. The world population model proposed by Malthus, a British economist, in his work 'An Essay on the Principle of Population' published in the period of 1789~1826 is one of the early mathematical models on population changes. Malthus' models and the carrying capacity models of Verhulst in 1845 were based on exponential type functions. The independent research field of mathematical ecology has been started from Lotka's works in 1920's. Since then various different mathematical models has been proposed and examined. This article mainly deals with single species population change models expressed in terms of ordinary differential equations.

• Korean Journal of Environmental Biology
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• v.33 no.2
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• pp.160-169
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• 2015

Three unrecorded species of free-living marine nematodes, belonging to genus Enoplus Dujardin, 1845 collected from rocky intertidal seagrass on the eastern coast of Korea, are described and illustrated. Enoplus taipingensis Zhang and Zhou, 2012 is characterized by longer body size, a series of lateral setae throughout the tail in male, the presence of trumpet-shaped precloacal supplement with well-dilated proximal end, and the presence of spicules with five to eight semicircular plates. Enoplus meridionalis Steiner, 1921 is characterized by the presence of trumpetshaped precloacal supplement with slightly dilated proximal end, paired massive spicules, and tail with two pairs of stout terminal setae. Enoplus mammillatus Timm, 1959 is easily distinguished from the congeners by narrow tubular-shaped precloacal supplement. In this study, we provide detailed morphological features of three Enoplus species by differential interference contrast microscopy and scanning electron microscopy. This is the first report on the species of the genus Enoplus from the Korean waters.