• Journal of Microbiology and Biotechnology
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• v.29 no.4
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• pp.596-606
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• 2019

N-acyl-homoserine lactone quorum sensing (AHL-QS) has been shown to regulate many physiological behaviors in Serratia marcescens MG1. In the current study, the effects of AHL-QS on the biosynthesis of acid and neutral products by S. marcescens MG1 and its isogenic ${\Delta}swrI$ with or without supplementing exogenous N-hexanoyl-L-homoserine lactone ($C_6-HSL$) were systematically investigated. The results showed that swrI disruption resulted in rapid pH drops from 7.0 to 4.8, which could be restored to wild type by supplementing $C_6-HSL$. Furthermore, fermentation product analysis indicated that ${\Delta}swrI$ could lead to obvious accumulation for acidogenesis products such as lactic acid and succinic acid, especially excess acetic acid (2.27 g/l) produced at the early stage of fermentation, whereas solventogenesis products by ${\Delta}swrI$ appeared to noticeably decrease by an approximate 30% for acetoin during 32-48 h and by an approximate 20% for 2,3-butanediol during 24-40 h, when compared to those by wild type. Interestingly, the excess acetic acid produced could be removed in an AHL-QS-independent manner. Subsequently, quantitative real-time PCR was used to determine the mRNA expression levels of genes responsible for acidogenesis and solventogenesis and showed consistent results with those of product synthesis. Finally, by close examination of promoter regions of the analyzed genes, four putative luxI box-like motifs were found upstream of genes encoding acetyl-CoA synthase, lactate dehydrogenase, ${\alpha}$-acetolactate decarboxylase, and Lys-like regulator. The information from this study provides a novel insight into the roles played by AHL-QS in switching from acidogenesis to solventogenesis in S. marcescens MG1.

• Fisheries and Aquatic Sciences
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• v.22 no.9
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• pp.20.1-20.8
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• 2019

Background: Despite the favorable geo-climatic potential of Cameroon, the national production of tilapia remains low due to poor tilapia growth reported by fish farmers. One of the underlying reasons is the early female maturation at a very small size and precocious breeding in earthen ponds, resulting in overpopulation which leads to stunted growth and therefore to the production of unmarketable fish size. Studies have shown that dietary supplementation of G. kola enhanced growth in young Clarias gariepinus and Oreochromis niloticus. It was also reported that G. kola inhibited spawning in Tilapia adult females. Therefore, this study sought to assess the effects of Garcinia kola as growth promoter and inhibitor of gonadal development in young Oreochromis niloticus. Methods: A total of 108 juveniles weighing $13.32{\pm}0.62g$ were randomly distributed in 9 hapas of 12 fishes each (9 females and 3 males) and fed for 70 days with three isonitrogenous diets, 40% crude protein with increasing Garcinia kola supplementation levels of 0 (normal diet), 6% and 10% (experimental diets). Physico-chemical parameters of the water (temperature, dissolved oxygen, pH, nitrate, nitrite, ammonia, and transparency) were measured twice a week. Every 14 days, fish were harvested, counted, and weighed. At the end of the experiment, three fish of each sex per replicate were sacrificed and their gonad and liver collected and weighed. Data were statistically analyzed using one-way analysis of variance repeated measure followed by Newman-Keuls multiple tests. Results: The results showed that all physico-chemical parameters of the water were within the recommended values for Tilapia culture. Tilapia fed 6% Garcinia kola supplemented diet displayed higher final body weight in males ($38.60{\pm}3.50g$) and females ($36.77{\pm}3.62g$) compared to those receiving normal diet ($36.23{\pm}1.36g$ and $25.87{\pm}3.32g$; respectively to the final body weight in males and females). The gonadosomatic index and hepatosomatic index indicated no significant variation in males while in females, these were significantly low in the experimental fish compared to control fish. Conclusion: The results of this study demonstrated that supplementation of G. kola seeds in diets of young Tilapia improved growth performance and impaired gonadal development in females.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.533-536
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• 2019

Recombinant baculoviruses are widely used to express heterologous genes in cultured insect cells. Recombinant baculoviruses can serve as gene-transfer vectors for expression of recombinant proteins in a wide range of mammalian cell types. Baculovirus system has significant benefits in view of safety, large-scale, and high level of gene expression. In this study, baculoviral vectors which were reconstructed from pOPINEneo-3C-GFP vector, were recombined with cytomegalovirus (CMV) promoter, green fluorescent protein (GFP), and p53 with NcoI and XhoI. These recombinant vectors were infected with various cells and cell lines. The baculovirus vector thus developed was analyzed by comparing the metastasis and expression of the recombinant genes with conventional vectors. These results suggest that the baculovirus vector has higher efficiency in metastasis and expression than the control vector. This work was supported by a grant from Mid-Career Researcher Program(NRF-2016R1A2B4016552) through the National Research Foundation of Korea(NRF) funded by the Ministry of Science, ICT & Future Planning(MSIP).

• Proceedings of the Korean Society of Toxicology Conference
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• 2000.11a
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• pp.45-67
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• 2000

2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) is a mutagenic and carcinogenic heterocyclic amino found in cooked meat. The in vivo mutagenicity and hepatocarcinogenicity of MeIQx were examined in mice harboring the lacZ mutation reporter gene ($Muta^{TM}$ Mice) and bitransgenic mice over-expressing the c-myc oncogene. C57B1/$\lambda$lacZ and bitransgenic c-myc (albumin promoter)/$\lambda$lacZ mice were bred and weaned onto an AIN-76 based diet containing $0.06\%$ (w/w) MeIQx or onto control diet. After 30 weeks on diet, only male bitransgenic mice on MeIQx developed hepatocellular carcinoma ($100\%$ incidence) indicating that there was synergism between c-myc over-expression and MeIQx. By 40 weeks, hepatic tumor incidence was $100\%$ ($17\%$) and $44\%$ ($0\%$) in male c-myc/$\lambda$lacZ and C57B1/$\lambda$lacZ mice given MeIQx (or control) diet, respectively, indicating that either MeIQx or c-myc over-expression alone eventually induced hepatic tumors. At either time point, mutant frequency in the lacZ gene was at least 40-fold higher in MeIQx-treated mice than in control mice of either strain. These findings suggest that MeIQx-induced hepatocarcinogenesis is associated with MeIQx-induced mutations. Elevated mutant frequency in MeIQx-treated mice also occurred concomitant with the formation of MeIQx-guanine adducts as detected by the $^{32}P$-postlabeling assay. Irrespective of strain or diet, sequence analysis of the lacZ mutants from male mouse liver showed that the principal sequence alteration was a single guanine-base substitution. Adenine mutations, however, were detected only in animals on control diet. MeIQx-fed mice harboring the c-myc oncogene showed a l.4-2.6-fold higher mutant frequency in the lacZ gene than mice not carrying the transgene. Although there was a trend toward higher adduct levels in c-myc mice, MeIQx-DNA adduct levels were not significantly different between c-myc/$\lambda$lacZ and C57B1/$\lambda$lacZ mice after 30 weeks on diet. Thus, it appeared that factors in addition to MeIQx-DNA adduct levels, such as the enhance rate of proliferation associated with c-myc over-expression, may have accounted for a higher mutant frequency in c-myc mice. In the control diet groups, the lacZ mutant frequency was significantly higher in c-myc/$\lambda$lacZ mice than in 057B1/$\lambda$1acZ mice. The findings are consistent with the notion that c-myc over-expression is associated with an increase in mutagenesis. The mechanism for the synergistic effects of c-myc over-expression on MeIQx hepatocarcinogenicity appears to involve an enhancement of MeIQx-induced mutations.

• Proceedings of the KSAR Conference
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• 2003.06a
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• pp.46-46
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• 2003

Interleukin-10 (IL-10) is a homodimeric protein with a wide spectrum of anti-inflammatory and immune activities. It inhibits cytokine production and expression of immune surface molecules in various cell types. The transgenic mice carrying the human IL-10 gene in conjunction with the bovine $\beta$-casein promoter produced the human IL-10 in milk during lactation. Transgenic mice were generated using a standard method as described previously. To screen transgenic mice, PCR was carried out using chromosomal DNA extracted from tail or toe tissues with a primer set. In this study, stability of germ line transmission and expression of IL-10 gene integrated into host chromosome were monitored up to generation F15 of a transgenic line. When female mouse of generation F9 was crossbred with normal male, generation F9 to F15 mice showed similar transmission rates (66.0$\pm$20.13%, 61.5$\pm$16.66%, 41.1$\pm$8.40%, 40.7$\pm$20.34%, 61.3$\pm$10.75%, 49.2$\pm$18.82%, and 43.8$\pm$25.91%, respectively), implying that the IL-10 gene can be transmitted stably up to long term generation in the transgenic mice. For ELISA analysis, IL-10 expression levels were determined with an hIL-10 ELISA and a mIL-10 ELISA kit in accordance with the supplier's protocol. Expression levels of human IL-10 from milk of generation F9 to F13 mice were 3.6$\pm$1.20 mg/ml, 4.2$\pm$0.93 mg/ml, 5.7$\pm$1.46 mg/ml, 6.3$\pm$3.46 mg/ml, and 6.8$\pm$4.52 mg/ml, respectively. These expression levels are higher than in generation F1 (1.6 mg/ml) mice. We concluded that transgenic mice faithfully passed the transgene on their progeny and successively secreted target proteins into their milk through several generations, although there was a little fluctuation in the transmission frequency and expression level between the generations.

• Korean Journal of Animal Reproduction
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• v.24 no.4
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• pp.419-428
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• 2000

Leptin, the product of obese (ob) gene, is an adipocyte-derived satiety factor that plays a major role in the regulation of food intake, energy homeostasis, body weight, reproductive physiology and neuropeptide secretion. The present study was designed to generate transgenic mice expressing antisense mouse ob (mob) gene. Total RNA was extracted from the adipose tissues of mouse, then reverse transcription was performed. The 303 and 635 bp fragments of anti I and II cDNAs were amplified from mob cDNAs by PCR. The two mob cDNAs were reversely ligated into between adipose tissue specific aP2 promote and SV40 poly(A) site. Transgenic mice carrying two different kinds of antisense mob transgenes were generated by DNA microinjection into pronucleus. Total 14 transgenic mice were born, and the 4 and 5 founder lines of the transgenic mice with anti I and II transgenes were respectively established. Antisense mRNA expression was detected in transgenic F$_1$ mice by RT-PCR analysis. This result suggests that the transgenic mice expressing antisense mob mRNA may be useful as an animal disease model to be obesity caused by decreased amount of leptin secretion.

• Journal of Plant Biotechnology
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• v.50
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• pp.56-62
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• 2023

Transgenic lilies have been obtained using Agrobacterium tumefaciens (AGL1) with the plant scale explants, followed by DL-phosphinothricin (PPT) selection. In this study, scales of lily plants cv. "red flame" were transformed with the pCAMBIA3301 vector containing the gus gene as a reporter and the blpR gene as a selectable marker, as well as a gene of interest showing herbicide tolerance, both driven by the CaMV 35S promoter. Using a 20-minute infection time and a 5-day cultivation period, factors that optimized and demonstrated a high transformation efficiency were achieved. With these conditions, approximately 22-27% efficiency was observed for Agrobacterium-mediated transformation in lilies. After transformation with Agrobacterium, scales of lilies were transferred to MS medium without selective agents for 2 weeks. They were then placed on selection MS medium containing 5 mg/L PPT for a month of further selection and then cultured for another 4-8 weeks with a 4-week subculture regime on the same selection medium. PPT-resistant scales with shoots were successfully rooted and regenerated into plantlets after transferring into hormone-free MS medium. Also, most survived putatively transformed plantlets indicated the presence of the blpR gene by PCR analysis and showed a blue color indicating expression of the gus gene. In conclusion, when 100 scales of lily cv. "red flame" are transformed with Agrobacterium, approximately 22-27 transgenic plantlets can be produced following an optimized protocol. Therefore, this protocol can contribute to the lily breeding program in the future.

• Journal of the Korean Institute of Landscape Architecture
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• v.42 no.1
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• pp.27-40
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• 2014

The functions of urban open space, which embraces community revitalization, are diverse. It is the means of public healthcare, learning centers for children, hub of arts and cultural programs, as well as promoter of urban tourism. However, in-depth discourse and research on the topic of urban open spaces has been limited so far. Hence, this study aims to investigate the motivations and satisfaction of visitation based on four representative waterfront open space in Seoul; Cheongyecheon Waterfront, Seoul Forest Park, Seonyudo Park and Banpo Hangang Park. The methods of study are literature review, observation investigation, and questionnaire survey. The findings are analyzed through the Exploratory Factor Analysis, Reliability Analysis, ANOVA Analysis and Regression Analysis by SPSS 18.0. The results of the study are as follows. First, urban waterfront open spaces in Seoul has 5 factors of visitor motivation; community amenity, nature access, cultural and educational assets, aesthetic enjoyment, and lastly means of escape. Second, factors of recognizing urban waterfront open spaces as community amenity and nature access indicate meaningful differences in visitor's perception by spatial characteristics. Third, distances between the destination and the visitor's residence influence significantly their perceived motivation. Close-range visitors perceived nature access as a principal factor, whilst medium to long-range visitors perceived visitation for aesthetic purposes more importantly. Lastly, the will to escape was shown as the influential factor in visitor satisfaction. Visiting open spaces for the enjoyment of nature and aesthetic purposes were factors that also closely relate to visitor satisfaction. In addition, it was found that there are different visitor motivations that influence visitor satisfaction in accordance with the spatial characteristics of each open space. In summary, it can be said that urban waterfront open space is a hybrid space connected to various types of urban contents beyond daily experiences. It was found that several visitor motivations including community development, design aesthetics, education and culture, entertainment, enjoyment of natural landscape, and relaxation, affect the overall satisfaction of the visiting experience. It is anticipated that the results of the study will be used by the local government in setting up strategies for the creation and management of successful urban waterfront open space, and for those involved in planning and design act as a starting point for spatial programming and amenities arrangement in accordance to the city's tourism and urban marketing approach.

• Clean Technology
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• v.21 no.1
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• pp.76-82
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• 2015

Volatile organic compounds (VOC) free adhesives have been interested by many scientists and engineers due to environmental regulations and the safety of industrial workers. In this work, a series of composites composed with bisphenol A epoxy resin used as solvent, dicyandiamide, and promoter were prepared to investigate the most appropriate molar ratio for steel-steel adhesion. The cured test specimen of each composite were measured with universal testing machine (UTM) to figure out mechanical properties such as tensile strength, Young’s modulus, and elongation. Furthermore, the lap shear strength of the specimen was tested with UTM while impact resistance was measured with Izod impact tester. The composite whose molar ratio of epoxy resin to curing agent is 1 : 0.9 (sample 3), showed better tensile strength, coefficient of elastic modulus, elongation, and impact strength than other composites did. The highest tanδ from dynamic mechanical analysis (DMA) was observed from sample 2 (epoxy resin: dicy = 1 : 0.7) while sample 3 showed slightly lower tanδ than that of 2. The morphology of the fracture surface of the cured composites from SEM showed that the number of subtle lines on the surface caused by impact increase as the contents of amine curing agent accrete. Furthermore, the viscosity change of sample 5 (epoxy resin: dicy = 1 : 1.3) was observed to confirm its storage stability.

• Journal of Plant Biotechnology
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• v.35 no.1
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• pp.87-94
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• 2008

Porcine epidemic diarrhea virus (PEDV) is an infectious and highly contagious virus of swine. In order to develop the transgenic tobacco culture cells producing PEDV antigen protein, four vectors expressing PEDV spike protein (SP) gene under the control of a CaMV 35S promoter were constructed. Four fragments of the SP region of PEDV, SP1 (444 bp, 1487-1930 bp), SP2 (1.7 kb, 2300-3987 bp), SP3 (1.4 kb, 1559-2950 bp), and SP4 (2.6 kb, 9-2643 bp) were amplified by PCR and then C-MYC tag was fused to the end of each SP gene, respectively. These cassettes are inserted into the pCAMBIA2300 (named as 35S::SP1-M, 35S::SP2-M 35S::SP3-M, and 35S::SP4-M, respectively). Tobacco (cv. BY-2) cultured cells were transformed by co-cultivation with Agrobacterium tumefaciens harboring expression vector. We selected kanamycin-resistant calli and checked for the presence of the introduced SP gene using PCR, resulting 70% of them showed the foreign gene. We selected the lines with high-level expression of PEDV antigen protein based on dot blot analysis. Southern blot analysis confirmed that the PEDV SP gene was integrated into the genome of the tobacco cultured cells. Northern blot analysis showed that the introduced gene was highly expressed in transgenic cultured cells. Transgenic tobacco cultured cells-derived antigen induced immunogenicity in mice as determined by a plaque reduction neutralization assay. These results suggest that the vectors expressing PEDV spike protein gene in this study will be useful for the development of transgenic plants and cultured cells producing PEDV antigene protein.