• Journal of Microbiology and Biotechnology
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• v.27 no.9
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• pp.1692-1700
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• 2017

Ralstonia solanacearum causes bacterial wilt in a wide variety of host plant species and produces a melanin-like blackish-brown pigment in stationary phase when grown in minimal medium supplemented with tyrosine. To study melanin production regulation in R. solanacearum, five mutants exhibiting overproduction of melanin-like pigments were selected from a transposon (Tn) insertion mutant library of R. solanacearum SL341. Most of the mutants, except one (SL341T), were not complemented by the original gene or overproduced melanins. SL341T showed Tn insertion in a gene containing a conserved domain of eukaryotic transcription factor. The gene was annotated as a hypothetical protein, given its weak similarity to any known proteins. Upon complementation with its original gene, the mutant strains reverted to their wild-type phenotype. SL341T produced 3-folds more melanin at 72 h post-incubation compared with wild-type SL341 when grown in minimal medium supplemented with tyrosine. The chemical analysis of SL341T cultural filtrate revealed the accumulation of a higher amount of homogentisate, a major precursor of pyomelanin, and a lower amount of dihydroxyphenylalanine, an intermediate of eumelanin, compared with SL341. The expression study showed a relatively higher expression of hppD (encoding hydroxyphenylpyruvate dioxygenase) and lower expression of hmgA (encoding homogentisate dioxygenase) and nagL (encoding maleylacetoacetate isomerase) in SL341T than in SL341. SL341 showed a significantly higher expression of tyrosinase gene compared with SL341T at 48 h post-incubation. These results indicated that R. solanacearum produced both pyomelanin and eumelanin, and the novel hypothetical protein is involved in the negative regulation of melanin production.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.4 no.1
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• pp.43-70
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• 1994

The effects of potassium chromate (500ppm/500ppm), potassium dichromate (500ppm/500ppm), cobalt chloride (100ppm/10ppm), methylmercuric chloride (100ppm/10ppm) on the biosynthesis of phospholipid and their composition of fatty acids in E.coli and B.subtilis were analyzed. The contents of phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol, phosphatidylglycerol, cardiolipin and total lipids in treatment with metal compounds were lower to compare with the control. The major fatty acid utilized for biosynthesis of phospholipid was palmitic acid in control of E.coli and B.subtilis. However, in treatment with metal compounds, changes of fatty acid composition utilized for phospholipid formation were as follows. In E.coli major fatty acids were palimitic acid (ave. 26.26%) and cis-vaccenic acid (ave. 10.94%) in treatment with potassium chromate, palmitic acid (ave. 31.41%/31.42%) and stearic acid (ave. 17.92%/19.41%) in treatment with potassium dichromate and cobalt chloride. And in treatment with raethylmercuric chloride, palmitic acid (ave. 26.66%), stearic acid (ave. 15.50%) and cis-vaccenic acid (ave. 20.59%) were used in phospholipid formation. In B.subtilis, the major fatty acid was palmitoleic acid (ave. 15.29% /10.22%) in treatment with potassium chromate and cobalt chloride, and stearic acid (ave. 16.01%) in treatment with potassium dichromate. On the other hand, cis-vaccenic acid (ave. 9.09%), palmitic acid (ave. 17.23%), stearic acid (ave. 6.66%), myristic acid (ave. 6.34%) and lauric acid (ave. 4.75%) were analyzed into major fatty acids in treatment with methylmercuric chloride. As shown in results, specific fatty acid pattern was came out in treatment with metal compounds according to bacteria and treatments.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.4
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• pp.413-420
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• 2017

The increase in the number of mud shrimps Upogebia major is a concern because of their negative effects on shellfish aquaculture, including Manila clam Venerupis philippinatum along the west coast of Korea. This study developed a behavioral analysis system for aquatic animals using a set of monochromatic light-emitting diode (LED) modules covering the visible light range at similar intervals. Movements of mud shrimp were monitored using a tracking system under illumination with infra-red light and an LED of 660 nm wavelength without provoking stimulation. The minimum light intensity needed to induce a photoresponse by the mud shrimp was $10{\mu}mole/m^2/s$ under the conditions tested. Of the six kinds of LED illuminations tested, the most sensitive response was obtained with illumination with the 505 nm LED, followed in order by LEDs with peak wavelengths of $525nm{\fallingdotseq}465nm$ > $405nm{\fallingdotseq}590nm$ > 660 nm. These findings should help to identify LED sources that efficiently induce movement of the mud shrimp and also for monitoring movement without stimulating.

• Journal of The Korean Association For Science Education
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• v.37 no.4
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• pp.659-668
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• 2017

This study was conducted to identify whether there is a significant difference in the developmental stages of the evolution concept depending on the major and the country. For this study, college students (both biology major and non-biology major) in Korea and the United States answered evolution concept assessment developed by Ha (2007). The data were analyzed based on the method of developed by Ha (2016). As a result of this study, Cronbach alpha for internal consistency reliability and MNSQ indices for item response fitness of the ordered multiple choice method providing 0 to 4 point scores to creationism, teleology, intentionality, use/disuse, and natural selection respectively, satisfied the benchmark. The level of Korean college students' evolution concepts was located in use/disuse and the level of USA college students' evolution concepts was located in teleology. No interaction effect was found between the difference of conceptual progressions of evolution concept by major and country and evolution contexts (human, animal, and plant). There was a significant relationship between developmental stages of evolution concept and their religiosity. Based on the results of this study, we discuss developmental characteristics of evolutionary concepts.

• Korean Journal of Environmental Biology
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• v.39 no.4
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• pp.495-506
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• 2021

In this study, using a continuous behavior measurement technique, the short-term behavioral responses and tolerance limits of red seabream Pagrus major fingerlings to sudden exposure to low salinity in a controlled environment were observed. The activity of the fingerlings suddenly exposed to 21.4, 17.3, and 9.8 psu increased temporarily at the initial exposure to show irregular swimming behavior, but then recovered a stable activity pattern through rapid salinity adaptation. However, the organisms suddenly exposed to 7.3 and 4.3 psu could not withstand the salinity stress, and their swimming behavior was severely disturbed and all individuals died within 48 hours. The findings suggest that red seabream underwent a temporary salinity stress process at the beginning of the exposure to concentrations of 10.0 psu or higher. At these concentrations, osmotic control was possible within at least 11 hours, so stable metabolic activity was also possible. However, organisms suddenly exposed to concentrations below 5.0 psu exceeded the tolerance to low salinity and the sublethal limit. In red seabream exposed to this concentration range, severe behavioral and metabolic disturbances were observed, and death was observed due to osmotic control failure. In conclusion, a salinity range of 5.0 to 10.0 psu can be predicted to correspond to a concentration range in which the osmotic control ability of the red seabream fingerlings is lost, and sub-lethal reactions occur.

• Proceedings of the Korean Society of Life Science Conference
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• 2005.09a
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• pp.83-83
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• 2005

• Proceedings of the Microbiological Society of Korea Conference
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• 2005.05a
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• pp.220.4-220
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• 2005

• Proceedings of the Zoological Society Korea Conference
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• 2001.10a
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• pp.113.2-113
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• 2001

No Abstract, See Full Text

• Proceedings of the Zoological Society Korea Conference
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• 1995.10b
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• pp.93-93
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• 1995

No Abstract, See Full Text

• Proceedings of the Zoological Society Korea Conference
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• 2000.10a
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• pp.145.1-145
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• 2000

No Abstract, See Full Text