Growth Characteristics of a Pyruvate Decarboxylase Mutant Strain of Zymomonas mobilis

Xun Zhao(순 자오),Peter L. Rogers(피터 로저스),Eilhann E. Kwon(권일한),Sang Chul Jeong(정상철),Young Jae Jeon(전용재) 한국생명과학회 2015 생명과학회지 Vol.25 No.11

에탄올 생산 세균 Zymomonas mobilis에서 에탄올 생산 경로의 핵심으로 작용하는 효소인, pyruvate decarboxylase (pdc) 유전자의 불활성 실험을 통해, PDC 활성이 50% 감소된 PDC 활성 변형균주가 분리되었다. 이러한 균주들의 에탄올 탄소대사 흐름이 고부가가치 화합물인 피루브산, 숙신산 및 젖산 등으로 전환되는지를 발효실험을 통해 평가하였다. 하지만 pdc의 발현을 중지시키기 위해 cat-삽입형-pdc와 pdc-결손형 아형 유전자를 전기 천공법을 이용해 야생형 균주 ZM4의 염색체에 이식하기 위한 다수의 시도에도 불구하고, 이러한 방법을 통해 분리된 균주들은 대부분 부분적 유전자 불활성 특성을 보였으며, PDC 활성이 완전히 손실된 삭제 돌연변이 균주를 획득할 수는 없었다. PDC활성이 변형된 돌연변이 균주의 발효 실험에서, 야생형 균주와 비교 시 감소된 PDC효소 활성의 변화로 인해 기질 흡수율과 에탄올 생산율이 감소되어 피루브산 생산이 약 2.5 g l-1 정도로 증가함을 확인하였으나, 젖산과 숙신산의 생산에 현저한 농도 변화를 보이지 못했다. 이러한 결과는 Z. mobilis의 산화환원 에너지가 PDC 효소 활성에 의한 에탄올 생산 경로에 전적으로 의존하여 발생한다는 것을 암시하였다. 상기 결과를 토대로 pdc 유전자의 완전한 불활성 유도와 산화환원 에너지의 균형은, 젖산 생산을 위한 lactate dehydrogenase, 숙신산 생산을 위한 pyruvate dehydrogenase와 malic enzyme과 같은 효소의 활성 증가를 통해, 세포내 NAD와 NADH 농도의 산화환원 균형이 이루어져야 발생할 수 있음을 시사하였다. Studies of the inactivation of a gene encoding pyruvate decarboxylase, pdc, in an ethanol-producing bacterium, Zymomonas mobilis, identified a mutant strain with 50% reduced PDC activity. To evaluate the possibility of a carbon-flux shift from an ethanol pathway toward higher value fermentation products, including pyruvate, succinate, and lactate, fermentation studies were carried out. Despite attempts to silence pdc expression in the wild-type strain ZM4 using cat-inserted pdc and pdc-deleted homologs by electroporation, the strain isolated showed partial gene activation. Fermentation experiments with the PDC mutant strain showed that the reduced expression level of PDC activity resulted in decreased rates of substrate uptake and ethanol production, together with increased pyruvate accumulation of 2.5 g l-1, although lactate and succinate concentrations were not significantly enhanced in these modified strains. Despite numerous attempts, no strains were isolated in which complete pdc inactivation occurred. This result indicates that the ethanol fermentation pathway of this bacterium is totally dependent on the activity of the PDC enzyme. To ensure a redox balance of intracellular NAD and NADH levels, other enzymes, such as lactate dehydrogenase for lactate, and enzymes involved in the production of succinic acid, such as pyruvate dehydrogenase (PDH) and malic enzymes, may be needed for their increased end-product production.

Long Noncoding RNA FBXL19-AS1-Mediated Ulcerative Colitis-Associated Intestinal Epithelial Barrier Defect

Zhao Xun,Cui De-Jun,Yang Liu-chan,Yuan Wen-Qiang,Yan Fang 한국조직공학과 재생의학회 2022 조직공학과 재생의학 Vol.19 No.5

BACKGROUND: This study commenced to uncover the role of long non-coding RNA FBXL19 antisense RNA 1 (FBXL19-AS1) in the development of ulcerative colitis (UC) and its possible mechanism. METHODS: FBXL19-AS1 expression in the colonic sigmoid mucosa of UC patients was detected. A colitis model was induced in mice using 5% dextran sodium sulfate. Hematoxylin–eosin staining was performed for histopathological examination. Apoptosis was detected by Tunel staining and tissue fibrosis was detected by immunohistochemistry. Also, intestinal permeability was examined. The concentrations of inflammatory factors IL-1b and IL-18 were detected by enzyme-linked immunosorbent assay. The relationship between FBXL19-AS1, miR-339-3p and RHOB was verified by RNA immunoprecipitation assay and dual luciferase reporter assay. RESULTS: The expression of FBXL19-AS1 was increased in dextran sodium sulfate (DSS)-induced colitis mouse model. FBXL19-AS1 interference or miR-339-3p overexpression inhibited DSS-induced colonic epithelial cell apoptosis and inflammatory response, and improved intestinal epithelial barrier defects, thereby ameliorating DSS-induced colitis injury in mice. FBXL19-AS1 sponged miR-339-3p while miR-339-3p targeted RHOB. Overexpression of RHOB reversed the protective effect of inhibition of FBXL19-AS1 on DSS-induced colitis in mice. CONCLUSION: FBXL19-AS1 reduces miR-339-3p-mediated targeting of RHOB and aggravates intestinal epithelial barrier defect in DSS-induced colitis in mice.

International Joint Ventures and Endogenous Protection: A Political-Economy Approach

( Lai Xun Zhao ) 세종대학교 경제통합연구소 (구 세종대학교 국제경제연구소) 1997 Journal of Economic Integration Vol.12 No.4

This paper constructs a model of international joint ventures (JVs) with political-economy considerations as the main motivation. A foreign firm decides whether to undertake full ownership foreign direct investment (FDI), or to form a JV with a home firm, while the home firm lobbies against FDI. It is shown that the level of lobbying is lower in the JV regime than in the FDI regime if the foreign firm transfer sufficiently advanced technology to the home firm through the JV. However, if the foreign firm anticipates future protectionist threats and forms a JV with the home firm beforehand (quid pro quo JV), then the foreign firm`s profit increases and the home firm`s level of lobbying decreases. (JEL Classification: F21, F12)

A Weibo Topic Tracking System based on K-means

Yun Liu,Kun-Peng Xia,Jian-Xun Zhao 보안공학연구지원센터 2014 International Journal of Database Theory and Appli Vol.7 No.6

This article studied weibo text representation. For the weibo features such as short, real-time, colloquialism and originality, in the original vector space model, we propose a suitable method for weibo text representation. Make all the content words as feature words after participation. And we proposed T-TFIDF weight calculation method according to the features of weibo. According to the vector space model, we proposed a weibo adaptive topic tracking methods based on K-means clustering. Simulation analysis shows that, the method can by comparing the similarity micro-blog and sub topic vector set, determine whether weibo belonging to the topic.

Artificial control maturation of porcine oocyte by dibutyryl cyclicAMP

Zhao, Ming-Hui,Jin, Yong-Xun,Lee, Seul-Ki,Kim, Nam-Hyung,Cui, Xiang-Shun TaylorFrancis 2014 Animal cells and systems Vol.18 No.1

<P>In this study, we investigated the effects of various durations of dibutyryl cyclic AMP (dbcAMP) treatment on the in vitro maturation (IVM) and subsequent development of parthenogenetically activated embryos. Immature porcine oocytes were cultured with or without 1 mM dbcAMP during the first 20, 28, or 36 h of culture, and then incubated for an additional 24 h without dbcAMP. The expression of <I>Wee1B, Myt</I>, and <I>Cdc25B</I> and the level of maturation promoting factor (MPF) in metaphase II oocytes were analyzed by real-time PCR (qRT-PCR) and enzyme linked immunosorbent assay (ELISA), respectively. The distribution of actin microfilaments in oocytes was also assessed. Subsequently, apoptotic cells in blastocysts from each group were visualized by transferase-mediated dUTP nick-end labeling staining. Results showed that oocytes extruded the first polar body between 12 and 18 h after being released from dbcAMP. MPF activity in oocytes at 28 + 24 h and 36 + 24 h after dbcAMP treatment was higher than that in the control group. Significantly more blastocysts were present among embryos in 28 + 24 h (54.28% vs. 39.11%, <I>P</I> < 0.05) and 36 + 24 h (47.24% vs. 32.94%, <I>P</I> < 0.05) groups than among embryos cultured in the absence of dbcAMP. However, the number of total and apoptotic cells was not significantly different between groups. The distribution of actin microfilaments was abnormal in oocytes cultured for 60 h without dbcAMP. In addition, the expression of <I>Wee1B, Myt</I>, and <I>Cdc25B</I> was higher in the control group at 44 h than in the dbcAMP group, but there were no differences in expression at the other time points. In conclusion, dbcAMP treatment delays oocyte maturation and maintains oocyte quality.</P>

Enantioselective Esterification of Ibuprofen by a Novel Thermophilic Biocatalyst: APE1547

Zhao Dan-tong,Xun Er-na,Wang Jia-xin,Wang Ren,Wei Xiao-fei,Wang Lei,Wang Zhi 한국생물공학회 2011 Biotechnology and Bioprocess Engineering Vol.16 No.4

The enantioselective esterification of ibuprofen catalyzed by a novel thermophilic esterase (APE1547)from the archaeon Aeropyrum pernix K1 was successfully conducted in organic solvents. The effects of acyl acceptor,substrate ratio, organic solvent, temperature, and water activity were investigated. Under optimum conditions, the highest enantioselectivity (E = 38.1) was obtained with a higher enzyme activity (216.5 μmol/g/h). Celites were added into the reaction mixture to remove the water produced in the esterification. The reaction achieved its equilibrium in approximately 96 h with a conversion of 57 and 99%(ee) of the un-reacted (S)-ibuprofen obtained.

Clinical Significance of Quantitative Analysis of Plasma Epstein-Barr Virus DNA in Patients of Xinjiang Uygur Nationality with Hodgkin's Lymphoma

Li, Xun,Yang, Shun-E.,Guo, Yun-Quan,Shen, Ming-Xia,Gu, Li,Gulikezi, Gulikezi,Zhao, Bing,Liu, Wei,Tuerxun, Tuerxun,Bai, Jing-Ping Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.12

Objective: To investigate the relationship between plasma EBV-DNA concentration and clinicopathologic features of Hodgkin's lymphoma cases. Methods: At first, the positive rate of plasma EBV-DNA was determined with a nested-PCR method using 45 specimens from Uygur HL patients, as well as 110 healthy people sampled as normal controls. Secondly, using fluorescent quantitative nested-PCR, EBV viral load was assessed in the EBV-DNA positive plasma samples. Then, relationships between plasma EBV viral load and clinicopathologic features of HL patients were analyzed. Results: The positive rate of plasma EBV-DNA of HL patients was significantly higher than that of normal controls (53.3% vs 26.4%, P=0.001). There was no significant difference about plasma EBV viral load between EBV-associated HL and EBV-DNA positive normal people (P=0.490). Looking at patients' characteristics, plasma EBV viral load in 10-20 years EBV-associated HL was higher than in EBV cases which were less than 10 years or more than 35 years (P=0.025). Furthermore, in EBV-associated HL, concentration of plasma EBV-DNA was significantly higher in advanced stage disease (stages III-IV; P=0.013), and with B-symptoms (P=0.020). Conclusion: EBV-DNA levels were associated with part of clinicopathologic features of cases. It was of practical use to screen HL. Further etiological studies appear warranted.

A Novel Accessory Molecule Trim59 Involved in Cytotoxicity of BCG-Activated Macrophages

Xiangfeng Zhao,Dongmei Yan,Qihui Liu,Baiqiu Du,Peng Li,Qu Cui,Xiao Han,Bairong Du,Xun Zhu 한국분자세포생물학회 2012 Molecules and cells Vol.34 No.3

BCG-activated macrophages (BAM) could kill the tumor cells through cell-cell contact. In this process membrane proteins play an important role. However, up to date, few membrane proteins were revealed. In this study, we se-lected a surface molecule named Trim59, which was spe-cifically expressed on BAM membrane (compared with the negative control). We cloned and prokaryoticly expressed the extracellular domain of Trim59, purified the recombinant protein and generated polyclonal antibodies. Immunohistochemistry showed that Trim59 abundantly expressed in spleen, stomach and ovary; intermediately expressed in brain, lung, kidney, muscle and intestine; but not in thymus, liver, heart, uterus. Using the antibodies to block Trim59 on BAM significantly reduced BAM cyto-toxicity against MCA207 cells. This demonstrated that Trim59 serves as an indispensable molecule in maintaining BAM activity. Overexpression of Trim59 in Raw264.7 cell line failed to lyse target MCA207 cells, which potentiated Trim59 per se could not enhance macrophage cytotoxicity; on another hand, overexpression of Trim59 enhance the pinocytosis and Phagocytosis activity of Raw-264.7, which imply Trim59 might mediate the cell-molecule interaction. Our results indicate Trim59 might be an essential accessory molecule in mediating BAM tumoricidal functions; and Trim59 is a phagocytosis-correlated molecule.

Effect of novel intensification structure on drying of particulate materials in spouted beds

Shengning Zhao,Feng Wu,Xiao-Xun Ma,Wenjing Zhou 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.114 No.-

Through the hot air-drying experiment, the differences in drying rate, unit energy consumption, and bedpressure drop of the conventional spouted bed (CSB), the spouted bed with an integral swirling bladenozzle (ISBN), the spouted bed with spherical longitudinal vortex generators (LVGs), and the integralmulti-jet spout-fluidized bed (IMJSFB) were studied. The Weibull distribution function was introducedto fit the drying data, and the differences in moisture diffusion coefficient, scale parameters, and dryingactivation energy of the four types of spouted beds were further discussed. The drying performanceparameters of the four types of spouted beds were comprehensively evaluated. The results show that,compared with the CSB, LVGs and IMJSFB reduce the activation energy of the drying process, while theISBN increases the activation energy of the drying process. The IMJSFB shows more excellent performancein terms of drying rate, scale parameters, unit energy consumption, and bed pressure drop, with the highestcomprehensive score. Compared with CSB, ISBN and LVGs, the IMJSFB is more suitable for drying wetparticles. For the IMJSFB, there exists an optimal value of particle diameter (d = 2 mm) for the drying process,which makes the particle drying rate reach maximum.

Histone deacetylase inhibitor trichostatin A affects porcine oocyte maturation in vitro

Jin, Yong-Xun,Zhao, Ming-Hui,Zheng, Zhong,Kwon, Jung-Suk,Lee, Seul-Ki,Cui, Xiang-Shun,Kim, Nam-Hyung CSIRO Publishing 2014 Reproduction, fertility, and development Vol.26 No.6

<P> Previous studies show that porcine oocyte aging resulting from asynchronised IVM impairs embryo developmental competence. In the present study we investigated whether trichostatin A (TSA; an inhibitor of histone deacetylation) prolongs the maturation time and prevents the aging of oocytes. Porcine oocytes were cultured in medium containing increasing concentrations of TSA (300 nM) for 24, 44 or 64 h. The percentage of oocytes that underwent germinal vesicle breakdown was significantly lower in the TSA-treated group (300 nM) than in the control group. TSA did not affect oocyte quality at MII based on levels of maturation-promoting factor, the phosphorylation status of mitogen-activated protein kinase or histone H3K9 acetylation analysis. We also compared the preimplantation developmental competence and the viability of pathenogenetic embryos treated with 100 nM TSA for 24 h and then continuously cultured for another 24 h in TSA free condition. No significant differences were observed for either parameter between the TSA-treated and control groups. These results indicate that TSA prolongs the IVM of porcine oocytes but that oocyte quality and aging are not affected. These findings provide a feasible option by which to adjust the initiation time of downstream experiments based on porcine matured oocytes. </P>