• Journal of Microbiology and Biotechnology
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• v.30 no.7
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• pp.1072-1081
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• 2020

Screening suitable strains with high temperature adaptability is of great importance for reducing the cost of temperature control in microalgae cultivation, especially in summer. To obtain high temperature-tolerant diatoms, water samples were collected in summer from 7 different regions of China across the Northeast, North and East. A total of 731 water samples was collected and from them 131 diatom strains were isolated and identified based on the 18S rRNA sequences. Forty-nine strains out of the 131 diatoms could survive at 30℃, and 6 strains with relatively high biomass and lipid content at high temperature were selected and were found to be able to grow at 35℃. Cyclotella sp. HB162 had the highest dry biomass of 0.46 g/l and relatively high triacylglycerol (TAG) content of 237.4 mg/g dry biomass. The highest TAG content of 246.4 mg/g dry biomass was obtained in Fistulifera sp. HB236, while Nitzschia palea HB170 had high dry biomass (0.33 g/l) but relatively low TAG content (105.9 mg/g dry biomass). N. palea HB170 and Fistulifera sp. HB236 presented relatively stable growth rates and lipid yields under fluctuating temperatures ranging from 28 to 35℃, while Cyclotella HB162 maintained high lipid yield at temperatures below 25℃. The percentage of saturated fatty acids and monounsaturated fatty acids in all the 6 strains was 84-91% in total lipids and 90-94% in TAGs, which makes them the ideal feedstock for biodiesel.

• Korean Journal of Agricultural Science
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• v.40 no.4
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• pp.367-375
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• 2013

The enzymatic interesterification was performed to produce structured lipids (SLs) with palm mid fraction (PMF) and stearic ethyl ester (STEE) for 1, 3, 6, 9, 12 and 15 hr at $80^{\circ}C$. The reaction was catalyzed by Lipozyme TLIM (immobilized lipase from Thermomyces lanuginosus, amount of 20% by weight of total substrates) in a shaking water bath set at 180 rpm. The optimum condition for synthesis of asymmetric SLs were: substrate molar ratio 1:0.5 (PMF:STEE, by weight), reaction time 6 hr, enzyme 20% (wt%, water activity=0.085) of total substrate and reaction temperature $80^{\circ}C$. After reaction at optimized condition, triacylglycerols (symmetrical and asymmetrical TAGs) from reactants were isolated. POP/PPO (1,3-palmitoyl-2-oleoyl glycerol or 1,2-palmitoyl-3-oleoyl glycerol), POS/PSO (palmitoyl-oleoyl-stearoyl glycerol or palmitoyl-stearoyl-oleoyl glycerol), SOS/SSO (1,3-stearoyl-2-oleoyl glycerol or 1,2-stearoyl-3-oleoyl glycerol) were obtained by solvent fractionation. Finally, refined SLs contained stearic acid of 16.91%. Solid fat index and thermogram of the refined SLs were obtained using differential scanning calorimetry. The degree of asymmetric triacylglycerol in the refined SLs was analyzed by Ag-HPLC equipped with evaporated light scattering detector (ELSD). The refined SLs consisted of symmetric TAG of 41.15 area% and asymmetric TAG of 58.85 area%.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.8
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• pp.1145-1152
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• 2012

This experiment was conducted with male chicks to investigate the influence of hormones and nutrients on the development of fatty liver syndrome (FLS) as well as the effects of dietary lipotropic factors on hepatic fat accumulation and lipogenic enzyme gene expression. A total of two-hundred sixteen 4-wk-old Hy-Line male chicks were divided into six groups and fed an experimental diet (T1, low-energy diet with low levels of lipotropic factors; T2, high-energy diet with low levels of lipotropic factors; T3 and T5, low-energy diet with high levels of lipotropic factors; T4 and T6, high-energy diet with high levels of lipotropic factors) for six weeks. The chicks in T5 and T6 groups were treated with intramuscular injections of estradiol benzoate for three days prior to biopsy and clinical analysis of FLS. Chicks treated with estrogen had significantly greater liver weights than untreated chicks. The abdominal fat contents were increased in chicks consuming high-energy diets as compared to those consuming low-energy diets. Treatment with estrogen significantly increased the concentrations of serum cholesterol, triacylglycerol and phospholipid (p<0.05). The hepatic triacylglycerol levels were tenfold higher in the estrogen treated chicks than in the untreated chicks. There were no significant differences in malondialdehyde levels between the treatment groups. Estrogen treatment dramatically increased the levels of fatty acid synthetase, acetyl-CoA carboxylase and ApoB mRNA. The results indicated that treatment with exogenous estrogen in growing male chicks induced hepatic fat accumulation, which might be partially due to increased lipogenic enzyme gene expression.

• Korean Journal of Agricultural Science
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• v.45 no.2
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• pp.265-282
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• 2018

The purpose of this research was to produce symmetric (Saturated-Unsaturated-Saturated, SUS) triacylglycerol (TAG) using palm stearin fraction oil (PSFO) and high oleic sunflower oil (HOSO) as substrates to replace cocoa butter. PSFO was blended with HOSO (1 : 2 weight ratio), and $lipozyme^{(R)}$ TLIM (20 weight % of the substrate) was added. Interesterification was carried out in a shaking water bath at $55^{\circ}C$ at 220 rpm for 6 hours. The response surface methodology (RSM) through the central composite face design was employed to observe the optimized SUS-TAG. The independent factors were the reaction temperature ($X_1$: 65, 75 and $85^{\circ}C$), reaction time ($X_2$: 1, 3 and 5 hours) and ratio of TLIM ($X_3$: 10, 15 and 20 weight %). The dependent variables were $Y_1$ = Saturated-Unsaturated-Unsaturated (SUU, area %), $Y_2=SUS$ (area %), $Y_3$ = Saturated-Saturated-Unsaturated (SSU, area %), $Y_4$ = Unsaturated-Unsaturated-Unsaturated (UUU, area %), and $Y_5=sn-2$ unsaturated fatty acid (area %). The optimal conditions from the central composite face design minimized acyl migration while maximizing the presence of unsaturated fatty acid at the sn-2 position (73.43 area %). The optimal conditions were $X_1=65^{\circ}C$, $X_2=1hour$, and $X_3=20weight%$. As a result of the response surface analysis, the lack of fits was found as $Y_1=0.622$, $Y_2=0.438$, $Y_3=0.264$, $Y_4=0.526$, and $Y_5=0.215$, and their $R^2$ were 0.897, 0.944, 0.826, 0.857, and 0.867, respectively.

• Korean Journal of Microbiology
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• v.39 no.3
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• pp.155-160
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• 2003

The wild type and two morphological variants of Streptomyces viridochromogenes were studied for their lipidand fatty acid compositions at different incubation temperatures. It showed that a decrease in triacylglycerol content was closely linked to the aerial mycelium formation. Phospholipids showed no characteristic changes, except that the contents of phosphatidylethanolamine were clearly high for aerial mycelium deficient strain BR2 grown at $20^{\circ}C$. The strain BR2 also presented unidentified aminolipids with various $R_{f}$ values. Among the aminolipids, ornithinolipid increased gradually during the cultivation for all strains. The changes in fatty acid compositions showed a temperature dependency that the proportion of unsaturated acids decreased as the growth temperature increased. The proportion of straight chain saturated fatty acids decreased as the aerial mycelium developed, and it was most evident for the mutant strain M13 with more extensive aerial mycelium. The mutant strain BR2 presented significantly higher level of iso branched odd numbered saturated fatty acids.

• Korean Journal of Community Nutrition
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• v.9 no.4
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• pp.528-535
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• 2004

In order to observe the effects of resistant starches on human glycemic response, nine female university students were investigated using cellulose (CED), resistant starch 3 (RS3D) and resistant starch 4 (RS4D) diets. Each woman's blood sugar and insulin, triacylglycerol and free fatty in plasma concentration were measured at fasting state, then 15, 30, 45, 60, 75, 90 and 120 minute after each test diet feeding. Glycemic indices of the Cellulose diet (CED: 57.9 $\pm3.00$), the Resistant starch 3 diet (RS3D: 52.6 $\pm7.9$) and the Resistant starch 4 diet (RS4D: 52.9 $\pm10.2$) were similar to each other, but they were significantly lower in comparison with those of white wheat bread diet (WWBD: 100). Insulinemic indices of the CED (49.8 $\pm8.2$), RS3D (50.0 $\pm7.3$) and RS4D (72.4 $\pm7.7$) were significantly lower in comparison with the white wheat bread diet (WWBD: 100), but among the dietary fiber diets, the insulinemic index of RS4D was significantly higher than the CED and the RS3D. Plasma triacylglycerol contents of the CED, RS3D and RS4D including WWBD showed gradual increase in tendency after lowering in early stage of each test diet feeding, but not significantly different in each dietary fiber added diet. Plasma free fatty acid contents of the CED, RS3D and RS4D including WWBD showed gradual decrease in tendency after each test diet feeding, but not significantly different by each dietary fiber added diet. In above results, we speculate that resistant starch 3 controls rapid elevation of blood sugar by delaying intestinal digestion and absorption of cellulose, but the result appears to be different from RS4 in comparison. Thus, RS3 intakes may contribute to the diet therapy of diabetic humans, but more studies on RS4 is needed in the future. (Korean J Community Nutrition 9(4): 528∼535, 2004)

• Preventive Nutrition and Food Science
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• v.15 no.4
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• pp.275-281
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• 2010

The chemical characteristics of seed oils of Asian ginseng (Panax ginseng C.A. Meyer) at different ages grown in Korea (3, 4 and 5-year old) and China (5-year old), and American ginseng (Panax quinquefoliu L., 5-year old) grown in China were compared. Total fatty acid composition showed a significantly higher oleic acid content in American (87.50%) than in Korean (68.02~69.14%) and Chinese ginseng seed oils (61.19%). At the sn-2 position, the highest oleic acid (81.09%) and lowest linoleic acid (15.77%) were found in American ginseng seed oil. The main triacylglycerol species in ginseng seed oils were triolein (OOO) and 1,2-dioleoyl-3-linoleoyl-glycerol (LOO)/1,3-dioleoyl-2-linoleoyl-glycerol (OLO). In addition, the seed oils possessed an ideal oxidative stability showing 16.55~23.12 hr of induction time by Rancimat test. The results revealed that ginseng seed oil could be developed as a new healthy edible oil, and that the oil's chemical characteristics were strongly associated with the ginseng species and habitats.

• Korean Journal of Veterinary Research
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• v.35 no.3
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• pp.489-496
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• 1995

Artemisia messes-schmidiana var viridis(Compositae) has been used for jaundice, hepatitis, diuretic and liver cirrhosis etc. 1-naphthylisothiocyanate(ANIT) has been used as a model compound to study mechanisms of intrahepatic cholestasis in laboratory animals as rat and mouse. The purposes of present study are to examine pharmacological effects of Artemisia messes-schmidiana var viridis water extract(AMWE) on alterations of triacylglycerol, cholesterol, protein, albumin and A/G ratio levels in serum, of histopathological appearances of liver, and that of hepatic microsomal cytochrome P-450 contents. Increased serum triacylglycerol levels by ANIT were significantly decreased with AMWE. However, AMWE posttreatment aggravated ANIT-induced cholesterol increase. Serum total protein and albumin contents, and A/G ratio were decreased in all ANIT-treated groups, and there were increased compared with control by AMWE posttreatment. Hepatic microsomal cytochrome P-450 contents were decreased in either AMWE and ANIT treatment, which greatly increased with AMWE pretreatment. On the other hand, in histological findings, our results shown that ANIT induced increase of lipid droplets and widening of sinusoidal capillary and these phenomena were disappeared with AMWE treatment. In conclusion, AMWE have choleresis effect. Also, AMWE improved lipid metabolism, protection and regeneration of hepatocytes in ANIT-induced cholestasis.

• Molecules and Cells
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• v.43 no.1
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• pp.48-57
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• 2020

The microalga Chlamydomonas reinhardtii accumulates triacylglycerols (TAGs) in lipid droplets under stress conditions, such as nitrogen starvation. TAG biosynthesis occurs mainly at the endoplasmic reticulum (ER) and requires fatty acid (FA) substrates supplied from chloroplasts. How FAs are transferred from chloroplast to ER in microalgae was unknown. We previously reported that an Arabidopsis thaliana ATP-binding cassette (ABC) transporter, AtABCA9, facilitates FA transport at the ER during seed development. Here we identified a gene homologous to AtABCA9 in the C. reinhardtii genome, which we named CrABCA2. Under nitrogen deprivation conditions, CrABCA2 expression was upregulated, and the CrABCA2 protein level also increased. CrABCA2 knockdown lines accumulated less TAGs and CrABCA2 overexpression lines accumulated more TAGs than their untransformed parental lines. Transmission electron microscopy showed that CrABCA2 was localized in swollen ER. These results suggest that CrABCA2 transports substrates for TAG biosynthesis to the ER during nitrogen starvation. Our study provides a potential tool for increasing lipid production in microalgae.

• Journal of Microbiology and Biotechnology
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• v.33 no.12
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• pp.1563-1575
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• 2023

Acyl-coenzyme A (CoA):diacylglycerol acyltransferase 2 (DGAT2) catalyzes the last stage of triacylglycerol (TAG) synthesis, a process that forms ester bonds with diacylglycerols (DAG) and fatty acyl-CoA substrates. The enzymatic role of Dgat2 has been studied in various biological species. Still, the full description of how Dgat2 channels fatty acids in skeletal myocytes and the consequence thereof in glucose uptake have yet to be well established. Therefore, this study explored the mediating role of Dgat2 in glucose uptake and fatty acid partitioning under short interfering ribonucleic acid (siRNA)-mediated Dgat2 knockdown conditions. Cells transfected with Dgat2 siRNA downregulated glucose transporter type 4 (Glut4) messenger RNA (mRNA) expression and decreased the cellular uptake of [1-¹⁴C]-labeled 2-deoxyglucose up to 24.3% (p < 0.05). Suppression of Dgat2 deteriorated insulin-induced Akt phosphorylation. Dgat2 siRNA reduced [1-¹⁴C]-labeled oleic acid incorporation into TAG, but increased the level of [1-¹⁴C]-labeled free fatty acids at 3 h after initial fatty acid loading. In an experiment of chasing radioisotope-labeled fatty acids, Dgat2 suppression augmented the level of cellular free fatty acids. It decreased the level of re-esterification of free fatty acids to TAG by 67.6% during the chase period, and the remaining pulses of phospholipids and cholesteryl esters were decreased by 34.5% and 61%, respectively. Incorporating labeled fatty acids into beta-oxidation products increased in Dgat2 siRNA transfected cells without gene expression involving fatty acid oxidation. These results indicate that Dgat2 has regulatory function in glucose uptake, possibly through the reaction of TAG with endogenously released or recycled fatty acids.