• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.352.1-352.1
• /
• 2016

양자점은 나노미터 크기의 반도체 결정으로 밴드갭에 따라 광학적, 전기적 성질이 달라지는 독특한 성질을 가지는 형광물질으로 활발히 연구되고 있다. 중금속을 기반으로 한 양자점은 높은 발광효율과 광안전성을 가지며, 가시광선 영역에서 빛을 내는 특징을 가지고 있다. 그러나 중금속을 사용하기 때문에 독성이 있어 인체나 환경에 유해하여 응용 연구에 제한적이다. 반면에, 탄소 기반의 양자점은 중금속 기반의 양자점과 비슷한 성질을 가질 뿐만 아니라, 높은 용해도와 낮은 독성으로 인해 생체적합성이 높다는 장점이 있다. 이를 이용하여 발광다이오드(LEDs), 태양전지, 광촉매 뿐만 아니라 바이오이미징, 바이오센서 등 생물학분야에도 응용 될 수 있다. 본 연구에서는 Bottom-up 합성 방법으로 유기전구체를 이용하여 질소를 함유하고 있는 양친매성 탄소 양자점(N-GQDs)을 합성하였다. 합성에 사용한 유기전구체는 기존에 보고된 유기전구체와 다르게 반응 진행 중에도 pH 측정 결과 중성을 나타내며, 반응 온도($225^{\circ}C$)와 유사한 온도에서도 pH 값은 여전히 6.0 이상의 값을 나타냈다. 중성을 띄는 특징으로 인해 추가적인 산제거 과정이나 표면안정화 과정이 필요 없다는 장점을 가지고 있다. 합성된 N-GQDs는 높은 결정성의 원형구조를 가지며, 원자힘현미경(AFM) 분석을 통해 높이가 ~ 1.5 nm 미만으로 3층 이하의 두께로 형성되었음을 확인하였다. 또한, 적외선 분광법(FT-IR) 분석을 통해 O-H기, 방향족 고리의 C = C (또는 C = N)기 및 C-N기가 각각 ~3250, ~1670과 ~1140 cm-1에서 확인할 수 있다. 합성된 양자점을 유기태양전지의 active layer에 소량(2 wt%) 첨가하여 양자점의 광학적, 전기적 성질을 확인하였다. 비교군 유기태양전지보다 N-GQDs가 첨가된 유기태양전지의 외부양자효율(PCE)이 7.3%에서 8.4%로 약 20%가 증가하는 것을 보였다. 이는 양자점이 상대적으로 흡수가 약한 단파장 영역의 빛을 흡수하고 PL을 내어 active layer로 에너지 트랜스퍼 현상이 일어나 전자전달을 원활하게 해 주기 때문이다. 앞으로 본 연구의 가능성과 추가적인 연구를 통해 더 많은 분야에 응용되기를 기대한다.

• Development and Reproduction
• /
• v.4 no.1
• /
• pp.29-35
• /
• 2000

A phosphatidylinositol 3-kinase (PI3K) is a upstream component of insulin signaling by which protein synthesis can be stimulated in many systems. To elucidate involvement of PI3K and its downstream mammalian target of rapamycin (mTOR) in the insulin signaling in pleimplantation mouse embryos, 8-cell embryos were cultured to blastocysts in the presence or absence of insulin and／or inhibitor drugs. The number of blastomeres per blastocyst, protein synthesis, and protein phosphorylation were examined. There was significant difference in embryonic development to blastocyst stage and hatching was potentiated by the insulin supplementation. The increase in the mean celt numbers per blastocyst was apparent in the insulin culture. Wortmannin, a PI3K inhibitor and rapamycin, an inhibitor of mTOR abolished the stimulatory effect of insulin on morphological development mitosis and protein synthesis. In autoradiography, phosphoproteins pp22 and pp30 which undergo phosphorylation in response to insulin were identified. Taken together, it can be suggested that PI3K and mTOR engaged in insulin signaling in the mouse embryo 8-cell onward and mediate embryotropic offset of insulin.

• Development and Reproduction
• /
• v.2 no.1
• /
• pp.39-43
• /
• 1998

The synthesis of steroid hormone starts from cholesterol. Steroidogenic acute regulatory protein(StAR) transfers cholesterol acutely from the outer mitochondrial membranes to the inner in the early step of steroidogenesis. Many kinds of steroid hormones are mainly synthesized in adrenal grand, ovary and testis. The purpose of this study is to determine the distribution of StAR mRNA in the rat ovary and adrenal gland and to confirm the functions of StAR in these organs. In the ovary, StAR mRNAs were strongly expressed in the corpus luteum, where progesterone is synthesized, and these were weakly expressed in the theca layer of follicles, where androgen is synthesized. However, StAR mRNAs were not detected in the estrogen producing granulosa cells of growing follicles. In the corpus luteum, StAR mRNAs were strongly loclized in the zona fasciculata and zona reticularis, where glucocorticoid is mainly synthesized. StAR mRNAs were weakly expressed in the zona gromerulosa, where mineralcorticoid is synthesized. StAR mRNAs were not detected in the adrenal medulla. In our results, StAR mRNAs were expressed differentially in the steroidogenic cells of ovary and adrenal gland according to the types of steroid hormones, and the statges of corpus luteum development. We conclude that StAR is involved in the steroidogenesis at the very early step of steroid synthesis cascade.

• Korean Chemical Engineering Research
• /
• v.48 no.5
• /
• pp.545-555
• /
• 2010

Recently, droplet-based microfluidic systems are widely used in various areas ranging from fundamental science including chemistry, biology, and physics to material science and engineering. This article reviews recent development in the droplet based microfluidic system from basic fabrication of tiny device, principle of droplet formation, merging, mixing, control of droplets, and application for the synthesis of novel functional materials. We discuss strong advantages of the droplet based microfluidics in point of control of particle size, morphologies, shapes, and structures.

• Journal of Life Science
• /
• v.3 no.4
• /
• pp.194-208
• /
• 1993

DNA 복제시 중추적 단백질은 DNA 합성을 수행하는 DNA polymerase이다. 따라서 DNA polymerase의 구조 및 기능에 대한 연구는 DNA polymerase의 중합반응에 대한 기작을 비롯하여 교정 및 수선기능에 대한 정보를 얻게 함으로써 복잡한 DNA 복제 기적을 이해하는 첩경이 된다. Bacteriophage T7의 Gene 5 단백질은 T7 DNA polymerase로 Richardson group에 의해 처음으로 발견되었으며, E. coli의 12 KDa thioredoxin과 tight complex를 형성한다. T7 DNA polymerase의 클로닝은 분자생물학의 새로운 장을 열어준 중요한 의미를 지닌다 . 본 연구에서는 T7 DNA polymerase의 구조적, 기능적 특성을 파악하고 DNA 염기서열 분석에의 응용 및 DNA 염기서열 결정을 위한 새로운 전략 및 최근연구 동향에 대해 기술하였다.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1989.11a
• /
• pp.1-15
• /
• 1989

바이오트라이보로지(biotribology)란 생물학(biology)와 마찰학(tribology)의 합성어로서 그리이스어의 $\tau\rhoc\betao\sigma$(마찰하다)가 어원이며, 마찰 마모 윤활의 학술 용어 "tribology"가 영어로 된것은 1966년이다. 이때 마찰학이란 이학 또는 공학현상으로서 문제를 해석하는데 한정하였고 생물에 대한 문제까지 광범위하게 고려하지 못하였다. 1972년 영국 석유학회, 기계학회 그리고 Rheology 학회의 공동개최로 "윤활제의 레올로지" 회의가 열렸다. 거기서 Dowson 교수(기계공학)와 Right 교수(루마치스 의학)의 공동논문 "Bio-Tribology"를 발표해서 처음으로 그 용어를 제안하였다. Dowson 교수가 열거했던 바이오트라이보로지의 대상은 다음과 같다. (1) 기계에 사용되는 윤활제에 대한 미생물의 영향 (2) 인간의치의 마모 (3) 면도칼에 대한 저마찰 보호막의 작용 (4) 인체내의 유체수송(뇨관내의 유동기구, 타액의 운동, 혈액흐름) (5) 모세혈관내에서 적혈구의 운동과 혈장에서 그의 윤활작용 (6) 화상치료시 "정압기체 축수"적 부양 (7) 음식물을 씹을 때 타액의 윤활작용 (8) 관절기능의 윤활학적 연구 (9) 인공골두와 인공관절의 윤활학적 연구8) 관절기능의 윤활학적 연구 (9) 인공골두와 인공관절의 윤활학적 연구

• Journal of Science and Technology Studies
• /
• v.17 no.1
• /
• pp.71-115
• /
• 2017

In 1953, theoretical physicist George Gamow attempted to explain the process of protein synthesis by hypothesizing that the base sequence of DNA encodes a protein's amino acid sequence and, in response, proposed the nucleic acid-protein information transfer model, which he dubbed the "diamond code." After expressing interest in discussing the daring hypothesis, contemporary biologists, including James Watson, Francis Crick, Sydney Brenner, and Gunther Stent, were soon invited to join the RNA Tie Club, an informal research group that would also count biologists and various researchers in physics, mathematics, and computer engineering among its members. In examining the club's formation, growth, and decline in multidisciplinary research on deciphering the genetic code in the 1950s, this paper first investigates whether Gamow's idiosyncratic approach could be adopted as a collaborative research forum among contemporary biologists. Second, it explores how the RNA Tie Club's research agenda could have been expanded to other relevant research topics needing multidisciplinary approach? Third, it asks why and how the RNA Tie Club dissolved in the late 1950s. In answering those questions, this paper shows that analyses on the intersymbol correlation of the overlapping code functioned to integrate diverse approaches, including sequence decoding and statistical analysis, in research on the genetic code. As those analyses reveal, the peculiar approaches of the RNA Tie Club could be regarded as a useful method for biological research. The paper also concludes that the RNA Tie Club dissolved in the late 1950s due to the disappearance of the collaborative research agenda when the overlapping code hypothesis was abandoned.

• Journal of Dairy Science and Biotechnology
• /
• v.39 no.2
• /
• pp.78-85
• /
• 2021

Previously, we showed that oral administration of probiotics, Lactobacillus acidophilus NS1 (LNS1), improved insulin sensitivity in high-fat-diet-fed mice (HFD mice). Furthermore, LNS1-conditioned media (LNS1-CM) reduced HNF4α transcription activity and the expression of phosphoenol pyruvate carboxykinase (PEPCK), a key enzyme in gluconeogenesis in HepG2 cells. In this study, we demonstrated that LNS1 administration increased the expression of glycosyltransferase 2 (GYS2) and glucose transporter 2 (GLUT2), while reduced the expression of glucose-6-phosphatase (G6PC) expression in liver of HFD mice. Furthermore, LNS1 suppressed hepatic expression of glucokinase regulatory unit (GCKR) in HFD mice without changing the mRNA levels of glucokinase (GCK), suggesting that LNS1 may inhibit nuclear GCK activity. Consistently, addition of LNS1-CM to HepG2 cells increased the mRNA levels of GYS2 and GLUT2 with reduced mRNA levels of G6PC and GCKR. Moreover, hepatic glycogen contents were increased in HFD mice upon administration of LNS1. Together, these results suggest that LNS1 facilitates glycogen accumulation in liver by regulating the expression of genes involved in glycogen metabolism, contributing to improved insulin sensitivity in the HFD mice.

• The Korean Journal of Nuclear Medicine
• /
• v.1 no.2
• /
• pp.27-34
• /
• 1967

1. Within experimental chromatin, the total protein: DNA ratio did not vary in the same organs of control and irradiated rats. However, the amount of RNA and total protein associated with the DNA varied considerably among the different types of chromatin. In particular, the content of chromatin was the highest in the irradiated tissue, and the lowest in the chromatin control tissue. RNA and total protein ratio of chromatins from brain, liver, testis and spleen declined with experimental organs. 2. There was the same quantitative relationship between the amount of RNA and the amount histone-protein associated with DNA in each chromatin. 3. RNA:DNA ratio of chromatin showed a $1.5{\sim}2$ times increase in the irradiated organs except brain. However, RNA:DNA ratio was decreased in chromatin by irradiation. 4. Histone-protein:Residual protein ratio was greatly varied among the organs. However, the effect was not found by irradiation. 5. Priming activity of chromatins showed a higher value in testis and the activity was greater in organs with higher metabolic activity. 6. Inhibition of Actinomycin D observable in chromatin for testis, liver, spleen and brain declined without relationship between irradiated and non-irradiated conditions. Ammonium sulfate in DNA of chromatin from histone showed increased priming activity with dissociation by Electrostatics. It may give different effect of ammonium sulfate on stimulation by property of chromatins. 7. It is suggested that the results support a proposal that the higher sensitivity of radioactive in testis, spleen by irradiated showed a increase and decrease lower-sensitivity of radioactive from brain, liver than did priming activity under the radioactive conditions.

• Development and Reproduction
• /
• v.10 no.2
• /
• pp.127-133
• /
• 2006

[ $17\;{\alpha}-hydroxylase/17,20-lyase(P450_{C17})$ ] is the key enzyme mediating the conversion of progesterone to $17\;{\alpha}-hydroxyprogesterone$, ultimately to androstenedione during steroidogenesis. R. dybowskii's ovarian $P450_{C17}$ cDNA was cloned to understand the regulatory mechanism of ovarian steroidogenic pathway at the molecular level in amphibian. A 2.5kb cDNA clone encoding a single open-reading frame with a 519 deduced amino acid was isolated with the screening of ovarian cDNA library. This sequence contained the three highly conserved domains as seen in $P450_{C17}$ of other species. The comparison of amino acid sequence of Rana $P450_{C17}$ with other animal's $P450_{C17}$ showed relatively high identity with 76% in Xenopus, 63% in chicken, 60% in rainbow trout, and 45% in human. Phylogenic analysis also indicated that Rana $P450_{C17}$ gene was evolutionary well conserved among vertebrate. Northern analysis indicated that the two different sizes of $P450_{C17}$ transcripts with approximately 2.5 and 3.6kb were detected in ovary tissue, but not in other tissues. The expression vector of Rana $P450_{C17}$ clearly showed the $17\;{\alpha}-hydroxylase$ activity converting the exogenous progesterone into $17\;{\alpha}-hydroxyprogesterone$ in the nonsteroidogenic COS-1 cells. Therefore, Rana $P450_{C17}$ cDNA is very useful to investigate the molecular mechanism of the ovarian steroidogenesis in amphibian.