• Title/Summary/Keyword: Temperature sensitivity

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Comparison of Results According to Reaction Conditions of Thyroglobulin Test (Thyroglobulin 검사의 반응조건에 따른 결과 비교 분석)

  • Joung, Seung-Hee;Lee, Young-Ji;Moon, Hyung-Ho;Yoo, So-yoen;Kim, Nyun-Ok
    • The Korean Journal of Nuclear Medicine Technology
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    • v.21 no.1
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    • pp.39-43
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    • 2017
  • Purpose Thyroglobulin (Tg) is a biologic marker of differentiated thyroid carcinoma (DTC), produced by normal thyroid tissue or thyroid cancer tissue. Therefore, the Tg values of DTC patients is the most specific indicator for judging whether recurrence occur or whether the remaining thyroid cancer is present. Thyroid cancer is currently the most common cancer in Korea, of which 90% is differentiated thyroid cancer. The number of patients with thyroid disease of this application also increased, and an accurate and prompt results are required. However, the incubation time of the Tg commonly takes about 24 hours in our hospital, and the result reporting time is delayed, and We could not satisfied with the requirements of clinical departments and patients. In order to fulfill these requirements, experiments were conducted by shortening the incubation time between company B's Kit currently in use and company C's Kit used in other hospitals. Through these experiments, we could perform the correlation with the original method and shortening method, and could find the optimum reaction time to satisfy the needs of the departments and the patients, and we will improve the competitiveness with the EIA examination. Materials and Methods In September 2016, we tested 65 patients company B's kit and company C's kit by three incubation ways. First method $37^{\circ}C$ shaking 2hr/2hr, Second method RT shaking 3hr/2hr, Third method 1hr/1hr shaking at $37^{\circ}C$. Fourth method RT shaking 3hr method which is the original method of Company C's Kit. Fifth method, the incubation time was shortened under room temperature shaking 2hr, Sixth method $37^{\circ}C$ shaking 2hr. And we performed and compared the correlation and coefficient of each methods. Results As a result of performing shortening method on company B currently in use, when comparing the Original method of company B kit, First method $37^{\circ}C$ shaking 2hr/2hr was less than Tg 1.0 ng/mL and the ratio of $R^2=0.5906$, above 1.0 ng/mL In the value, $R^2=0.9597$. Second method RT shaking 3hr/2hr was $R^2=0.7262$ less than value of 1.0 ng/mL, $R^2=0.9566$ above than value of 1.0 ng/mL. Third method $37^{\circ}C$ shaking 1hr/1hr was $R^2=0.7728$ less than value of 1.0 ng/mL, $R^2=0.8904$ above than value of 1.0 ng/mL. Forth, Company C's The original method, RT shaking 3hr was $R^2=0.7542$ less than value of 1.0 ng/mL, and $R^2=0.9711$ above than value of 1.0 ng/mL. Fifth method RT shaking 2hr was $R^2=0.5477$ less than value of 1.0 ng/mL, $R^2=0.9231$ above than value of 1.0 ng/mL. Sixth method $37^{\circ}C$ shaking 2hr showed $R^2=0.2848$ less than value of 1.0 ng/mL, $R^2=0.9028$ above than value of 1.0 ng/mL. Conclusion Samples with both values of 1.0 ng/mL or higher in both of the six methods showed relatively high correlation, but the correlation was relatively low less than value of 1.0 ng/mL. Especially, the $37^{\circ}C$ shaking 2hr method of company C showed a sharp fluctuation from the low concentration value of 1.0 ng/mL or less. Therefore, we are planning to continuously test the time, equipment, incubation temperature and so on for the room temperature shaking 2hr method and $37^{\circ}C$ shaking 1hr/1hr of company C which showed a relatively high correlation. After that, we can search for an appropriate shortening method through additional experiments such as recovery test, dilution test, sensitivity test, and provide more accurate and prompt results to the department of medical treatment, It is competitive with EIA test.

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Potential Study for the Sedimentary Exhalative Pb-Zn Mineralization in Dyusembay Area, Kazakhstan (카자흐스탄 듀셈바이지역의 퇴적분기형 연-아연 광화작용에 대한 잠재력 연구)

  • No, Sang-gun;Lee, Seung-han;Park, Ki-woong;Jeong, Hyeon-guk;Yun, Ji-seong;Kim, Sun-ok;Park, Maeng-eon
    • Economic and Environmental Geology
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    • v.51 no.3
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    • pp.213-222
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    • 2018
  • Metasediment-hosted Pb-Zn mineralized zone has been found in Dyusembay of Kazakhstan. Its petrological properties, metal index, alteration index and redox-sensitivity are compared with those of SEDEX type deposit. Mineralization is developed along foliation of host rock (graphitic phyllite) and controlled by folds and faults; major ore minerals including pyrite, pyrrhotite, sphalerite, and galena are disseminated or interlayered with fine-grained quartz. The margin of the mineralized zone is metamorphosed accompanying sericite and chlorite. Hydrothermal brecciation and Pb-Zn mineralization formed in quartz-calcite stockworks are confirmed at the around of Maytyubin granitoid intrusions. The mineralization is classified into three types according to those of occurrence, paragenesis, chemical composition and isotopic characteristics. Type 1 whose fine-grained pyrite, pyrrhotite and sphalerite are formed in parallel yet discontinuous to well-developed foliations of the host rock; its geochemistry is similar to those of the earlier stage in SEDEX-type mineralization. In case of type 2, the ore minerals of which are concentrated being parallel to a foliation by regional metamorphism, and most of them associated with quartz and muscovite (${\pm}$ biotite) paragenetically. Type 3 is formed in the hydrothermal breccia zone whose ore minerals are controlled by foliation and breccia and developed in quartz ${\pm}$ calcite veins having a form such as stratification, stockwork or veinlets. Host rocks in the mineralized zone indicate homogeneous metamorphic grade and there is no specific alteration zonation. Also, all types (type 1, type 2, and type 3) represent similar REEs patterns, it can be interpreted that these are originated from a same source. Sulphides occurred in mineralized zone indicate a limited range of sulphur isotope values (type 2, ${\delta}^{34}S=-13.3{\sim}-11.7$‰; type 3, ${\delta}^{34}S=-13.9{\sim}-8.2$‰), and a result of geothermometry presents different temperature ranges: type 2($251{\pm}38^{\circ}C{\sim}277{\pm}40^{\circ}C$); type 3($360{\pm}2^{\circ}C$ to $537{\pm}29^{\circ}C$). It is estimated to be due to the effect of metamorphism and Maytyubin granitoid intrusions, respectively. In addition, ternary chart of thorium, scandium, and zircon for discrimination of tectonic setting and redox sensitivity using V/Mo values indicate that hydrothermal sediments put on reduction environment after precipitation, before being affected by metamorphism and intrusion activity. Geochemical data are plotted on a distal trend of SEDEX-type with discrimination plot using SEDEX index. As a result, petrological-geochemical properties demonstrate that Dyusembay Pb-Zn mineralized zone is comparable to distal-type of SEDEX deposit.

The Study on Carbon Budget Assessment in Pear Orchard (배 재배지의 탄소수지 산정에 관한 연구)

  • Suh, Sanguk;Choi, Eunjung;Jeong, Hyuncheol;Lee, Jongsik;Kim, Gunyeob;Lee, Jaeseok;Sho, Kyuho
    • Korean Journal of Environmental Biology
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    • v.33 no.3
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    • pp.345-351
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    • 2015
  • This study was conducted to find out the methodology of carbon budget assessment among soil, atmosphere and plant. Soil respiration, net ecosystem productivity of herbs and net ecosystem productivity of woody plants have been measured in 30 years old pear orchard at Naju. Closed Dynamic Chamber (CDC) method was used to measure soil respiration and net ecosystem productivity of herbs. Net ecosystem productivity of woody plant (pear) was determined by eddy covariance method using the EddyPro (5.2.1) program. As for soil respiration, $429.1mgCO_2m^{-2}h^{-1}$ was released to atmosphere and sensitivity of soil temperature ($Q_{10}$) was 2.3. In case of herbs, respiration was superior to photosynthesis during measurement period. From 20 to 24 Jun 2015, the sum of absorbed and released $CO_2$ by herb's photosynthesis and respiration was $156.1mgCO_2m^{-2}h^{-1}$. Woody plants showed the $680.1mgCO_2m^{-2}h^{-1}$ of absorption by photosynthesis. In a farm scale, the sum of soil respiration, and net ecosystem productivity of herbs and woody plants was $0.04tonCO_2ha^{-1}$ during the measurement period, and it showed that pear orchard act as a $CO_2$ sink. This study using various approaches is expected to present a methodology for evaluating the carbon budget of perennial woody crop plantations.

Ecosystem Service Assessment of Urban Forest for Water Supply and Climate Mitigation of Seoul Metropolitan Area (환경공간정보를 이용한 수도권의 수자원 공급과 기후완화 기능을 위한 도시림의 생태계서비스 평가)

  • Lee, Soo Jeong;Yoo, Somin;Ham, Boyoung;Lim, Chul-Hee;Song, Cholho;Kim, Moonil;Kim, Sea Jin;Lee, Woo-Kyun
    • Korean Journal of Remote Sensing
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    • v.33 no.6_2
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    • pp.1119-1137
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    • 2017
  • This study assessed the water provisioning and climate mitigation ecosystem services of the urban forest in Seoul and Gyeonggi-do. The ecosystem service assessment is conducted based on natural function, natural function and population, and natural function and the beneficiary of the ecosystem service. Then, the impact of climate change on ecosystem services is analyzed to figure out the sensitivity of the impact on the beneficiary when the natural function of forest destroys under climate change. Gyeonggi-do has higher function-based water provisioning ecosystem service than Seoul. And population-based water provisioning ecosystem service appears to be higher in the densely populated area. On the other hand, beneficiary-based water provisioning ecosystem service by applying both natural water supply function and beneficiary distribution appears different with the result of population-based water provisioning service assessment. In other words, regions with high beneficiary population show higher ecosystem service than those with a low beneficiary population even though they have the same water storage function. In addition, climate change has a negative impact on the water provisioning ecosystem service. Under climate change, water provisioning service is expected to decrease by 26%. For climate mitigation service, regions close to the forest seem to have a low temperature, which indicates their high climate mitigation service. The center of the city with high beneficiary population shows high beneficiary-based ecosystem service. The climate change impacts the forest growth to decrease which affect the beneficiary-based climate mitigation ecosystem service to decrease by 33%. From this study, we conclude that beneficiary-based function and ecosystem service assessment is needed as well as the supply-based classification of forest function suggested by Korea Forest Service. In addition, we suggest that not only supply-based function classification and ecosystem service assessment but also beneficiary-based function classification and ecosystem service assessment is needed for managing the urban forest, which has been destroyed by climate change. This will contribute to revaluing cases where a forest with low natural function but high beneficiary-based ecosystem service, which is not considered under the current forest function-based assessment system. Moreover, this could assist in developing a suitable management plan for the urban forest.

Characterization of the cloned RNA1 gene of Saccharomyces cerevisiae (Cloning된 효모의 RNAI 유전자의 특성에 관하여)

  • Song, Young-Hwan;Kim, Dae-Young;Kim, Jin-Kyung
    • Journal of fish pathology
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    • v.6 no.2
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    • pp.93-101
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    • 1993
  • The RNAI mutation of Saccharomyces cerevisia is a recessive and temperature sensitive lethal mutation which interferes with the production of mRNA, rRNA, and tRNA. However, the precise role of RNAI gene have not been revealed until yet. We have cloned rna1-1 mutant gene from rna1-1 mutant yeast strain(R49 ; trpl, ura3-52, rna1-1). The 3.4kb BglII fragment of wild type RNAI clone(81-2-6) contains whole RNAI gene. The genomic southern blotting with BglII digested R49 genomic DNA as a probe shows the unique and identical band with wild type 3.4kb BglII fragment. Therefore, We prepared partial BglII genomic library(3~4kb BglII fragments) into BamH I site of pUC19. The rna 1-1 mutant clone was screened with Digoxigenin(DIG)-lableled probe by high density colony hybridization. The 5'-flanking region of rna1-1 gene was sequenced by dideoxy chain termination method. The 5'-flanking sequence of RNAI gene contains three TATA-like sequence ; TAATA, TATA and TTTTAA at position of -67, -45, and -36 from first ATG codon respectively. The 5'-flanking region of wild type RNA I gene from ATG codon to -103nt was deleted with Bal31 exonuclease digestion, generating $pUC{\Delta}$/RNA I. After constructing $pYEP{\Delta}RNA$ I (consists of -103nt deleting RNA I gene, URA3 gene, $2{\mu}m$ rep. origin), pYEPrna1-1(consists of Xba I fragment of pUCrna1-1. URA3 gene, $2{\mu}m$ rep. origin), and pYEPRNAI. each plasmid was transformed into host strain(trpl, ura3-52, rna1-1) by electroporation, respectively. Yeast transformant carrying $pYEP{\Delta}RNA$ I did not complement the thermal sensitivity of rna1-1 gene. It means that TATA-like sequences in 5'-flanking region is not TATA sequence for transcribing RNAI gene and there may be other essential sequence in upstream region for the transcription of RNAI gene.

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Validation of Satellite SMAP Sea Surface Salinity using Ieodo Ocean Research Station Data (이어도 해양과학기지 자료를 활용한 SMAP 인공위성 염분 검증)

  • Park, Jae-Jin;Park, Kyung-Ae;Kim, Hee-Young;Lee, Eunil;Byun, Do-Seong;Jeong, Kwang-Yeong
    • Journal of the Korean earth science society
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    • v.41 no.5
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    • pp.469-477
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    • 2020
  • Salinity is not only an important variable that determines the density of the ocean but also one of the main parameters representing the global water cycle. Ocean salinity observations have been mainly conducted using ships, Argo floats, and buoys. Since the first satellite salinity was launched in 2009, it is also possible to observe sea surface salinity in the global ocean using satellite salinity data. However, the satellite salinity data contain various errors, it is necessary to validate its accuracy before applying it as research data. In this study, the salinity accuracy between the Soil Moisture Active Passive (SMAP) satellite salinity data and the in-situ salinity data provided by the Ieodo ocean research station was evaluated, and the error characteristics were analyzed from April 2015 to August 2020. As a result, a total of 314 match-up points were produced, and the root mean square error (RMSE) and mean bias of salinity were 1.79 and 0.91 psu, respectively. Overall, the satellite salinity was overestimated compare to the in-situ salinity. Satellite salinity is dependent on various marine environmental factors such as season, sea surface temperature (SST), and wind speed. In summer, the difference between the satellite salinity and the in-situ salinity was less than 0.18 psu. This means that the accuracy of satellite salinity increases at high SST rather than at low SST. This accuracy was affected by the sensitivity of the sensor. Likewise, the error was reduced at wind speeds greater than 5 m s-1. This study suggests that satellite-derived salinity data should be used in coastal areas for limited use by checking if they are suitable for specific research purposes.

Study on hydroxy fatty acid contents changes and physiological responses under abiotic stresses in transgenic Camelina

  • Kim, Hyun-Sung;Lee, Hyun-Sook;Lim, Hyun-Gyu;Park, Won;Kim, Hyun-Uk;Lee, Kyeong-Ryeol;Ahn, Sung-Ju
    • Proceedings of the Korean Society of Crop Science Conference
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    • 2017.06a
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    • pp.191-191
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    • 2017
  • Hydroxy fatty acid (HFA) is an important industrial resource that known to be extracted from seeds of Castor or Lesquerella. However, mass production of HFA from those crops are difficult because of their behavior or life cycle. In this study, we applied HFA synthesis related gene FAH12, RcPDAT1, RcLPCAT, RcDGAT2, and RcPDCT on bioenergy crop Camelina sativa. Furthermore, we determined NaCl or cold stress tolerance changes of transgenic Camelina. RcFAH12, RcPDAT1, RcLPCAT, RcDGAT2, and RcPDCT genes were cloned into multigene expression vector which is engineered with seed specific promoter of FAE1 or Napin. Combination of HFA genes multi-expression vector constructs were divided into Set3 (RcFAH12, RcPDAT1-2, RcLPCAT), Set4 (RcFAH12, RcDGAT2, RCPDAT1-2, RcLPCAT), and Set5 (RcFAH12, RcDGAT2, RCPDAT1-2, RcLPCAT, RcPDCT). Transgenic HFA synthesis Camelina plants were generated using agrobacterium-mediated vacuum infiltration system. Results of fatty acid composition of T1 transgenic Camelina seeds analyzed by GC-MS showed 9.5, 9.0, and 13.6 % of HFA contents in Set3#6, Set4#8, and Set5#10, respectively. Therefore, seeds of T2 generation were harvest from Set5#10 which is shown highest HFA contents, and, 17.7, 8.1 and 10.5 % of HFA contents were determined in Set5#10-5, Set5#10-8, and Set#10-10, respectively. However, 7.7% of C18:2 and 22.3 % of C18:3 among unsaturated fatty acids were decreased in Set5#10-5 than WT. Meanwhile, we confirmed abiotic stress responses in T2 transgenic Camelina Set5#10-5 and Set5#10-10 under 0, 100, 150, and 200 mM NaCl or 25, 15, and $10^{\circ}C$ temperature for 5 weeks. Both Set5#10-5 and Set5#10-10 showed lower growth in height than WT in control and NaCl condition. Growth of leaf length and width were similar in WT and Set5#10-10 but lower in Set5#10-5 under NaCl stress. Number of opened flowers showed that both transgenic Camelina were lower than WT under normal condition. But, WT and Set5#10-10 showed similar opened flower number in 100 and 200 mM NaCl. In cold stress, 15 and $10^{\circ}C$ treatment for 5 weeks did not showed significant changes in between WT and both transgenic lines even they showed different growth rate in control condition. Taken together, growth and development are delayed by expression of exogenous HFA related genes in transgenic lines but relative abiotic stress sensitivity is similar with WT. In conclusion, reduced C18:2 or C18:3 fatty acid composition of seed by HFA synthesis is resulted from lack of resource supplement for development at seedling stage but it is not affect NaCl and cold stress tolerance.

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Development of Evaluation Method for Jointed Concrete Pavement with FWD and Finite Element Analysis (FWD와 유한요소해석을 이용한 줄눈콘크리트포장 평가법 개발)

  • Yun, Kyong-Ku;Lee, Joo-Hyung;Choi, Seong-Yong
    • International Journal of Highway Engineering
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    • v.1 no.1
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    • pp.107-119
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    • 1999
  • The joints in the jointed concrete pavement provide a control against transverse or longitudinal cracking at slab, which may be caused by temperature or moisture variation during or after hydration. Without control of cracking, random cracks cause more serious distresses and result in structural or functional failure of pavement system. However, joints nay cause distresses due to its inherent weakness in structural integrity. Thus, the evaluation at joint is very important. and the joint-related distresses should be evaluated reasonably for economic rehabilitation. The purpose of this paper was to develop an evaluation system at joints of jointed concrete pavement using finite element analysis program, ILLI-SLAB, and nondestructive testing device. FWD. To develop an evaluation system for JCP, a sensitivity analysis was performed using ILLI-SLAB program with a selected variables which might affect fairly to on the performance of transverse joints. The most significant variables were selected from precise analysis. An evaluation charts were made for jointed concrete pavement by adopting the field FWD data. It was concluded that the variables which most significantly affect to pavement deflections are the modulus of subgrade reaction(K) and the modulus of dowel/concrete interaction(G), and limiting criteria on the performance of joints at JCP are 300pci. 500,000 lb/in. respectively. Using these variables and FWD test, a charts of load transfer ratio versus surface deflection at joints were made in order to evaluate the performance of JCP. Practically, Chungbu highway was evaluated by these evaluation charts and FWD field data for jointed concrete pavement. For Chungbu highway, only one joint showed smaller value than limiting criterion of the modulus of dowel/concrete interaction(G). The rest joints showed larger values than limiting criteria of the modulus of subgrade reaction(K) and the modulus of dowel/concrete interaction(G).

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Study of Serious Bacterial Infections in Febrile Infants Younger than Three Months of Age (열이 있는 3개월 이하의 영아에서 세균성 감염의 예측에 대한 연구)

  • Jeon, Myeoung Won;Lee, Ji Young;Jang, Young Taek
    • Pediatric Infection and Vaccine
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    • v.10 no.2
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    • pp.215-222
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    • 2003
  • Purpose : This study was to analyze serious bacterial infections in infants younger than three months of age and to review the direction of treatments for these patients. Methods : 378 febrile infants with a rectal temperature ${\geq}38.0^{\circ}C$ visited from Jan. 2001 through Dec. 2002 were retrospectively studied. Infants with the following criteria belonged to the low risk group. WBC $5,000{\sim}15,000/mm^3$, WBC negative in urine stick test and negative for nitirite test, CSF WBC < $10/mm^3$ and negative in CSF gram stain, negative chest X-ray, stool WBC <5/HFP(high power field), and focal infection. If any of the above criteria were not met, they belonged to the high risk group. SBI was defined as a positive culture of urine, blood or CSF. SI was defined as aseptic meningitis or pneumonia including above laboratory tests of SBI. SBI patients were separately compared with two groups, high risk and low risk. Results : Of the 378 infants that were tested 216(57.1%) were in the high risk group and 162(42.9%) in the low risk group. Among 105 SBI(27.8%) and 172 SI(45.5%), there were 98 urinary tract infection(25.2%), 10 bacteremia(2.6%), 2 bacterial meningitis(0.6%), and 77 aseptic meningitis(22.8%). There were 76 SBI(35.2%) from the high risk group and 29 SBI(17.9%) from the low risk group identified. The results of the sensitivity(72.4%), the specificity(48.7%), the negative predictive value(82.1%) and the positive predictive value (35.2%) were calculated. Conclusion : Even though the probability of SBI in the low risk group is insignificant, it should still be considered in febrile infants younger than 3 months of age. I believe the CSF study is necessary because of the moderate high incidence of abnormal finding in our study.

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Role of Citrate Synthase in Acetate Utilization and Protection from Stress-Induced Apoptosis

  • Lee, Yong-Joo;Kang, Hong-Yong;Maeng, Pil Jae
    • Proceedings of the Microbiological Society of Korea Conference
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    • 2008.05a
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    • pp.39-41
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    • 2008
  • The yeast Saccharomyces cerevisiae has been shown to contain three isoforms of citrate synthase (CS). The mitochondrial CS, Cit1, catalyzes the first reaction of the TCA cycle, i.e., condensation of acetyl-CoA and oxaloacetate to form citrate [1]. The peroxisomal CS, Cit2, participates in the glyoxylate cycle [2]. The third CS is a minor mitochondrial isofunctional enzyme, Cit3, and related to glycerol metabolism. However, the level of its intracellular activity is low and insufficient for metabolic needs of cells [3]. It has been reported that ${\Delta}cit1$ strain is not able to grow with acetate as a sole carbon source on either rich or minimal medium and that it shows a lag in attaining parental growth rates on nonfermentable carbon sources [2, 4, 5]. Cells of ${\Delta}cit2$, on the other hand, have similar growth phenotype as wild-type on various carbon sources. Thus, the biochemical basis of carbon metabolism in the yeast cells with deletion of CIT1 or CIT2 gene has not been clearly addressed yet. In the present study, we focused our efforts on understanding the function of Cit2 in utilizing $C_2$ carbon sources and then found that ${\Delta}cit1$ cells can grow on minimal medium containing $C_2$ carbon sources, such as acetate. We also analyzed that the characteristics of mutant strains defective in each of the genes encoding the enzymes involved in TCA and glyoxylate cycles and membrane carriers for metabolite transport. Our results suggest that citrate produced by peroxisomal CS can be utilized via glyoxylate cycle, and moreover that the glyoxylate cycle by itself functions as a fully competent metabolic pathway for acetate utilization in S. cerevisiae. We also studied the relationship between Cit1 and apoptosis in S. cerevisiae [6]. In multicellular organisms, apoptosis is a highly regulated process of cell death that allows a cell to self-degrade in order for the body to eliminate potentially threatening or undesired cells, and thus is a crucial event for common defense mechanisms and in development [7]. The process of cellular suicide is also present in unicellular organisms such as yeast Saccharomyces cerevisiae [8]. When unicellular organisms are exposed to harsh conditions, apoptosis may serve as a defense mechanism for the preservation of cell populations through the sacrifice of some members of a population to promote the survival of others [9]. Apoptosis in S. cerevisiae shows some typical features of mammalian apoptosis such as flipping of phosphatidylserine, membrane blebbing, chromatin condensation and margination, and DNA cleavage [10]. Yeast cells with ${\Delta}cit1$ deletion showed a temperature-sensitive growth phenotype, and displayed a rapid loss in viability associated with typical apoptotic hallmarks, i.e., ROS accumulation, nuclear fragmentation, DNA breakage, and phosphatidylserine translocation, when exposed to heat stress. Upon long-term cultivation, ${\Delta}cit1$ cells showed increased potentials for both aging-induced apoptosis and adaptive regrowth. Activation of the metacaspase Yca1 was detected during heat- or aging-induced apoptosis in ${\Delta}cit1$ cells, and accordingly, deletion of YCA1 suppressed the apoptotic phenotype caused by ${\Delta}cit1$ mutation. Cells with ${\Delta}cit1$ deletion showed higher tendency toward glutathione (GSH) depletion and subsequent ROS accumulation than the wild-type, which was rescued by exogenous GSH, glutamate, or glutathione disulfide (GSSG). Beside Cit1, other enzymes of TCA cycle and glutamate dehydrogenases (GDHs) were found to be involved in stress-induced apoptosis. Deletion of the genes encoding the TCA cycle enzymes and one of the three GDHs, Gdh3, caused increased sensitivity to heat stress. These results lead us to conclude that GSH deficiency in ${\Delta}cit1$ cells is caused by an insufficient supply of glutamate necessary for biosynthesis of GSH rather than the depletion of reducing power required for reduction of GSSG to GSH.

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