• Asian-Australasian Journal of Animal Sciences
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• 제25권10호
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• pp.1473-1480
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• 2012

The Galactose-${\alpha}1$,3-galactose (${\alpha}1$,3Gal) epitope is responsible for hyperacute rejection in pig-to-human xenotransplantation. Human decay-accelerating factor (hDAF) is a cell surface regulatory protein that serves as a complement inhibitor to protect self cells from complement attack. The generation of ${\alpha}1$,3-galactosyltransferase (GGTA1) knock-out pigs expressing DAF is a necessary step for their use as organ donors for humans. In this study, we established GGTA1 knock-out cell lines expressing DAF from pig ear fibroblasts for somatic cell nuclear transfer. hDAF expression was detected in hDAF knock-in heterozygous cells, but not in normal pig cells. Expression of the GGTA1 gene was lower in the knock-in heterozygous cell line compared to the normal pig cell. Knock-in heterozygous cells afforded more effective protection against cytotoxicity with human serum than with GGTA1 knock-out heterozygous and control cells. These cell lines may be used in the production of GGTA1 knock-out and DAF expression pigs for xenotransplantation.

• Journal of Microbiology and Biotechnology
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• 제28권12호
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• pp.2009-2018
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• 2018

Leuconostoc mesenteroides can be used to produce mannitol by fermentation, but the mannitol productivity is not high. Therefore, in this study we modified the chromosome of Leuconostoc mesenteroides by genetic methods to obtain high-yield strains for mannitol production. In this study, gene knock-out strains and gene knock-in strains were constructed by a two-step homologous recombination method. The mannitol productivity of the pat gene (which encodes phosphate acetyltransferase) deletion strain (${\Delta}pat::amy$), the fk gene (which encodes fructokinase) deletion strain (${\Delta}fk::amy$) and the stpk gene (which encodes serine-threonine protein kinase) deletion strain (${\Delta}stpk::amy$) were all increased compared to the wild type, and the productivity of mannitol for each strain was 84.8%, 83.5% and 84.1%, respectively. The mannitol productivity of the mdh gene (which encodes mannitol dehydrogenase) knock-in strains (${\Delta}pat::mdh$, ${\Delta}fk::mdh$ and ${\Delta}stpk::mdh$) was increased to a higher level than that of the single-gene deletion strains, and the productivity of mannitol for each was 96.5%, 88% and 93.2%, respectively. The multi-mutant strain ${\Delta}dts{\Delta}ldh{\Delta}pat::mdh{\Delta}stpk::mdh{\Delta}fk::mdh$ had mannitol productivity of 97.3%. This work shows that multi-gene knock-out and gene knock-in strains have the greatest impact on mannitol production, with mannitol productivity of 97.3% and an increase of 24.7% over wild type. This study used the methods of gene knock-out and gene knock-in to genetically modify the chromosome of Leuconostoc mesenteroides. It is of great significance that we increased the ability of Leuconostoc mesenteroides to produce mannitol and revealed its broad development prospects.

• 오토저널
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• 제15권1호
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• pp.28-36
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• 1993

Present-day there are two of theories which have considerable scientific support to explain the knock phenomenon in S.I. engine, the detonation theory and the autoignition theory. But they still have some problems to explain effects of knock parameters, i.e.. compression ratio, spark timing, mixture quality, engine speed, ect, on knocking process in S.I. engine. Accordingly, it is essential to find out whish is more adequate theory of two and to develop the method of analyzing knock phenomenon, that is the aim of this paper. The Authors develop the method of predicting transient temperature and pressure at the end-gas zone during the combustion period and analyze knocking process by this method based on the knock theories. The caluculated values based on the autoignition theory show reasonablly correct relations between knock parameters and knock process but there is no evidence of knock occurred by detonation theory through the calculation according to the all parameters. The authors find out that the autoignition theory is more adequate than detonation theory to analyze knocking process in S.I. engine.

• 한국자동차공학회논문집
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• 제7권9호
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• pp.28-35
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• 1999

In this study, investigation of transient knock characteristics in a spark-ignition engine has been carried out. The universal knock threshold values were found by a DFDD method and a NSDBP method which is a non-dimensional version of the SDBP method. Also modified NSDBP method could be used for transient knock detection. In a commercial ECU , spark timing was retarded from the steady -state spark timing during rapid throttle opening to avoid uncomfortable feeling and knock. Knock usually occurred just after the start of rapid throttle opening when spark timing was set, as values for the steady state condition. We found that air/fuel ratio deeply involved with the knock during transient condition. Due to the difference of initial heat release rate, knock occurred more easily at rich air/fuel ratio than at lean air/fuel ratio.

• 한국자동차공학회논문집
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• 제5권3호
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• pp.202-208
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• 1997

The knocking is one of major parameters to improve engine performance in a spark ignition engine. Many researches have been carried out to identify them using cylinder pressure, vibration signal and so on. In the present study, measurement and analysis was conducted to set up the criteria of knock occurrence by using microphone signal. Cylinder pressure was measured for the reference signal of knocking. It has been observed that resonance frequencies of pressure wave are nearly independent of engine operating conditions such as engine speed, air fuel ratio, load and octane number of fuel within to limited experimental conditions. SDBP(sum of different band-pass data) method using resonance frequency of knock was proposed for estimating knock intensity. SDBP method is superior to identify knock occurrence and its intensity in case of sound pressure measurement.

• Asian-Australasian Journal of Animal Sciences
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• 제21권5호
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• pp.745-753
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• 2008

Gene-manipulated mice were discovered for the first time about a quarter century ago. Since then, numerous sophisticated technologies have been developed and applied to answer key questions about the fundamental roles of the genes of interest. Functional genomics can be characterized into gain-of-function and loss-of-function, which are called transgenic and knock-out studies, respectively. To make transgenic mice, the most widely used technique is the microinjection of transgene-containing vectors into the embryonic pronucleus. However, there are critical drawbacks: namely position effects, integration of unknown copies of a foreign gene, and instability of the foreign DNA within the host genome. To overcome these problems, the ROSA26 locus was used for the knock-in site of a transgene. Usage of this locus is discussed for the gain of function study as well as for several brilliant approaches such as conditional/inducible transgenic system, reproducible/inducible knockdown system, specific cell ablation by Cre-mediated expression of DTA, Cre-ERTM mice as a useful tool for temporal gene regulation, MORE mice as a germ line delete and site specific recombinase system. Techniques to make null mutant mice include complicated steps: vector design and construction, colony selection of embryonic stem (ES) cells, production of chimera mice, confirmation of germ line transmission, and so forth. It is tedious and labor intensive work and difficult to approach. Thus, it is not readily accessible by most researchers. In order to overcome such limitations, technical breakthroughs such as reporter knock-in and gene knock-out system, production of homozygous mutant ES cells from a single targeting vector, and production of mutant mice from tetraploid embryos are developed. With these upcoming progresses, it is important to consider how we could develop these systems further and expand to other animal models such as pigs and monkeys that have more physiological similarities to humans.

• 소성∙가공
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• 제12권6호
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• pp.582-587
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• 2003

This paper is concerned with the mechanical property changes of the milli-size products manufactured by forward extrusion processes with square dies. Experiments are carried out with pure aluminum and pure copper billets. Extrusion ratio and knock-out pad are chosen as the important process parameters affecting the changes of mechanical properties such as shear strength and hardness. Shear strength tests with the extruded milli-size pin have shown the strong relation between victors hardness and shear strength in the neck of a stepped pin. As the extrusion ratio increases, the hardness on both the surface and the center line of a pin also increase. It is also noted that the hardness on the surface is a little higher than that on the center. The existence of knock-out pad in extrusion die causes the hardness in the neck of a extruded pin to increase. Finally, the approximated linear relations between shear strength and hardness of a pin are suggested.

• Reproductive and Developmental Biology
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• 제32권3호
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• pp.205-209
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• 2008

본 연구는 돼지 $\beta$-casein 유전자 위치에서 EGFP가 발현될 수 있는 knock-in 벡터를 구축하기 위하여 실시되었다. 돼지의 $\beta$-casein 유전자를 이용하여 knock-in 벡터를 구축하기 위해 돼지의 태아 섬유아세포로부터 $\beta$-casein 유전자를 동정하였고 EGFP, SV4O polyA signal을 동정하였다. Knock-in 벡터는 5' 상동 영역 약 5 kb와 3' 상동 영역 약 2.7 kb로 구성되어있으며, positive selection marker로 $neo^{r}$ 유전자를, negative selection marker로 DT-A 유전자를 사용하였다. 구축된 knock-in 벡터로부터 EGFP의 발현을 확인하기 위하여 생쥐 유선 세포인 HC11 세포에 knock-in 벡터를 도입하였다. 그 결과 EGFP의 발현을 HC11 세포에서 확인하였다. 이와 같은 결과로서 이 block-in 벡터는 knock-in 형질전환 돼지를 생산하는데 사용될 수 있을 것으로 생각된다.

• 자연과학논문집
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• 제15권1호
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• pp.57-67
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• 2005

산화적 스트레스에 대한 Bacillus subtilis의 thiol peroxidase 유전자의 생리적인 기능을 연구하기 위해 thiol peroxidase 유전자의 기능이 손상된 녹아웃 돌연변이주를 상동성 재조합에 의해 제조하였다. 호기적 조건에서 배양할 때 야생형과 녹아웃 돌연변이주 사이에는 성장속도에서 차이를 관찰할 수 없었다. 그러나 paraquat 처리할 때와는 달리 $H_2O_2$와 cumene hydroperoxide (CHP)에 의한 산화적 스트레스에 대해 역할을 하고 있음을 시사하는 결과이다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2005년도 추계학술발표대회 및 정기총회
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• pp.603-606
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• 2005

하나의 유전자는 또 다른 유전자의 단백질과 프로모터 영역에서 Binding 함으로써 그 유전자의 발현에 영향을 미칠 수 있다. 이러한 두 유전자간의 조절 상호 작용을 유전자 조절망이라 하며 유전체의 핵심적인 기능을 보다 간결하게 표현하는 조절망을 설계할 수 있다. 대표적인 설계 방법으로는 Time-Series Data 를 이용한 방법과 Steady-State Data 를 이용하는 방법이 있으며 이 논문에서는 Steady-State Data 즉, Knock-out Data 를 이용하여 유전자 조절망을 재구성함으로써 기존의 방법을 개선하여 보다 정확한 결과 예측을 목표로 한다.