• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.2
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• pp.210-216
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• 1998

Relationship between population group properties and docosahexaenoic acid (DHA) content of the Pacific oyster had been carried out at the Bukman oyster farm near Tongyeong based on the regular monthly sampling from November 1994 through April 1996. DHA content in lipids was least abundant in June and most abundant in November. Minimum DHA content close to 'zero' in lune suggests that much of DHA are being used for maturing and discharging of eggs and sperms, in consideration of the fact that lure is the spawning periods of the oyster. The corelationships among DHA content, mortality, and growth coefficient, have not been recognized. The approximate positive relations have been acknowledged between DHA content and the individual density in times of harvest, and also the individual weight. But it seems that the relaltions between DHA content and the individual weight are not directly related, rather it seems that it is the result from the population density effects caused by the relations between DHA and the number of individuls. But the meaning of the above mentioned relations can not be clearly defined yet.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.1
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• pp.10-15
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• 2002

Environmental and medium factors were investigated as basic data for optimizing DHA production when using Thraustochytrium aureum. To study the effect of environmental conditions, the rotation speed and culture temperature were changed. Plus the trend of the growth characteristics, lipid content in the biomass, and DHA content in lipids were evaluated according to various initial glucose concentrations. The biomass, lipid, and DHA analyses showed that the physiological characteristics of T. aureum were closely related with the environmental and medium conditions, as in the case of other marine microorganisms. For example, a low rotation speed of 50 rpm lowered the cell growth rate as well as the DHA content in the lipids. A low temperature had a negative effect on the cell growth, yet a positive effect on the lipid content in the biomass. Different initial glucose concentrations had no effect on the lipid content in the biomass or DHA content in the lipids, yet did affect the cell growth. Accordingly, these results show that environmental and medium factors must be synthetically considered in order to optimize DHA production when using T. aureum.

• Journal of Nutrition and Health
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• v.32 no.5
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• pp.526-532
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• 1999

The aim of this study was to observe whether the dietary supplementation of docosahexaenoic acid(DHA). In growing rats requires extra supplementation of arachidonic acid(AA) for brain development. Sprague-Dawley rats were divided into three groups, each fed a different diet. In the FO group, dams were fed a DHA-rich FO diet during pregnancy and lactation and pups were fed the same diet until 10 weeks old. In the AO group dams and pups were similarly fed a FO diet after weaning. DHA and AA were most effetively deposited in the developing brain during pregnancy and lactation in rats. However, FO-W pups showed significantly lower level of DHA at 0-3 weeks compared with the FO and AO groups and than slowly increased DHA levels to about 87% of other groups at 10 weeks with the introduction of the FO diet after weaning. The total amount of DNA in whole brain rapidly reached a maximum level at 3 weeks and then was sustained at a constant level after 5 weeks of age. The DNA content was positively correlated with DHA level but not with AA level in the developing brain. DNA content was significantly lower in the FO-W group compared to the FO and AO group at 3 weeks of age. However, the DNA content of brain in FO-W pups increased to 80% of the FO group level at 10 weeks after feeding the FO diet after weaning. The relative percentage of AA in brain lipids was significantly reduced in the early stage of brain development when only DHA was supplemented. However, DHA supplementation had no significant effect on the incorporation of AA when the approximately 35% of LA in the FO diet was substituted by preformed AA. These results suggest that large quantities of DHA could interfere with the normal conversion of LA to AA if LA is not supplemented enough together with DHA. Therefore, high DHA supplementation may require preformed AA in the diet even though AA has no significant correlation with the DNA content in brain. DHA supplementation after weaning also improved the incorporation of DHA into brain and content of DNA even though brain development was almost completed, suggesting that a low level of DHA supplementation without AA addition might be necessary to improve brain development during infancy as well as during pregnancy and lactation.

• Journal of Nutrition and Health
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• v.31 no.7
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• pp.1100-1111
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• 1998

The incorporation of docosahexaenoic acid(DHA) and arachidonic acid(AA) into brain and liver lipid has been compared in male pups from binth to 10 weeks old by feeding DHA-rich experimental diets or chow diets to dams from pregnancy in rats. The experimental DHA-rich diets contained 7g fish oil and 3g corn oil per 100g diet. There were three experimental groups, FO-I : Dams were fed DHA-rich diet during pregnancy and lactation, and their it pups fed the same diet until 10 weeks old. FO-II Dams fed chow diet during pregnancy and DHA-diet during lactation, and their pups fed the same DHA-diet until 10 weeks. FO-III : Dams fed chow diet during gestation and lactation, and then the pups fed DHA-diet after weaning. The relative % of DHA in hepatic lipid was about 12% with chow diets, but increased rapidly to 20-25% level when DHA-rich diets were supplied after weaning. The AA(%) of FO-III group was relatively high when a chow diet containing higher amount of linoleic acid was given, but there was no significant difference between the groups after feeding on a DHA-rich diet. When the DHA-rich diet was supplied from pregnancy(FO-I), the relative % of DHA in brain lipid was 13.7% at birth and continuously increased to a maximum level(17.2%) at 3-weeks and then was sustained until 5 weeks old. Similar levels of DHA incorporation were observed when DHA-rich diet was supplied from lactation(FO-II). However, the pups of FO-III group showed significantly lower levels of DHA incorporation(72%) at birth. These livels slowly increased and reached an 87% level of FO-I at 10 weeks when the pups ate DHA-rich diets after weaning. The relative % of AA in brain lipid was 10.4% in the FO-I group at birth, which was significantly lower than those of other groups, but there was no significant difference between groups after feeding DHA-rich diets in all groups. The Ah(%) level increased to maximum(11-12%) at 3-weeks and then was slightly reduced and was sustained at about 10% after S-weeks. Total amounts of DNA in the whole brain rapidly reached maximum level at 3-weeks and then was sustained at a constant level after S-weeks. DNA content was not significantly different between groups at birth, but it was significantly higher in FO-I and FO-II groups than in FO-III group at 3-weeks. However, DNA content in FO-III group was continuously increased to 80% level of FO-I at 10-weeks after feeding DHA-rich diet since weaning. In conclusion, the DHA(%) in whole brain was most effectively deposited when DHA-rich diet had been supplied during pregnancy and lactation in rats. However, DHA supplementation after weaning also improved the incorporaton of DHA into brain and content of DNA even though brain development was almost completed, which suggests that DHA supplementation might be necessary to improve brain development in humans during infancy as well as pregnancy and lactation. (Korean J Nutrition 31(7) 1100-1111, 1998)

• Journal of Food Hygiene and Safety
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• v.26 no.4
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• pp.349-354
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• 2011

Our objective in this study is to assess the safety of docosahexaenoic acid (DHA) fortified milk of dairy cows fed feeds containing protected fish oil treated with formaldehyde by analyzing formaldehyde concentration in commercial milk and DHA fortified milk of dairy cows fed formaldehyde treated feed. There are 3 milk samples in this study: Commercial milk (CM), DHA fortified milk for Kid (DHA-K) and DHA fortified milk for Baby (DHA-B). We confirm the fresh quality of these three samples by physicochemical tests. In fat content result, three groups are significantly different at the p < 0.05 by Duncan's multiple range test, but fat content of group DHA-K is about half the level of the other two groups. Protein content of group DHA-K is 1 % higher than other two groups. According to the analysis result of DHA content of DHA fortified milk, DHA content of DHA-B is two-fold higher than DHA-K. Similar pattern was seen in the intake based on age. According to HPLC analysis result of formaldehyde concentration in milk, commercial milk and DHA fortified milk are between 0.013 ppm and 0.057 ppm which is formaldehyde standard level in fresh milk settled in WHO (World Health Organization). Three groups have no significantly differences at the p < 0.05 by Duncan's multiple range test. For this reason, it can be concluded that there is no transition of formaldehyde from dairy cows fed formaldehyde treated feeds to its produced milk. Safety about formaldehyde of DHA fortified milk of dairy cows fed formaldehyde treated feeds is considered similar to commercial milk.

• Korean Journal of Food Science and Technology
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• v.22 no.5
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• pp.520-525
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• 1990

A modified method of urea adduct formation, in which water and organic solvent were used as the wetting agent and the reaction medium. respectively, is suggested to obviate methanolysis and to ease recovery in the separation of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from fish oil. With the new method the fraction in which the total content of EPA. DHA and their precursors is more than 80% could be obtained. Although the total content of precursors in the concentrate was hardly affected by the kind of the wetting agent or the organic solvent, the content of EPA and DHA varied significantly depending on the organic solvent. This finding made it possible to selectively enrich the desired components. After DHA-enriched fraction (I)HA is 50%) was obtained by using pentane, EPA-enriched fraction ( EPA is 53%)) could be obtained from the residue of DHA-enriched fraction by using heptane.

• ALGAE
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• v.35 no.3
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• pp.277-292
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• 2020

Omega-3 fatty acids, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are polyunsaturated fatty acids beneficial to human health. A limited number of microalgae have been used for commercial omega-3 production, which necessitates the identification of new microalgae with high omega-3 contents. We explored the fatty acid composition and EPA and DHA contents of the mixotrophic dinoflagellate Gymnodinium smaydae fed with the optimal algal prey species Heterocapsa rotundata. Cells of G. smaydae were found to be rich in omega-3 fatty acids. In particular, the DHA content of G. smaydae was 21 mg g^-1 dry weight, accounting for 43% of the total fatty acid content. The percentage of DHA in the total fatty acid content of G. smaydae was the highest among the reported microalgae except for Crypthecodinium cohnii. Moreover, to determine if the prey supply interval affected the growth rate of G. smaydae and its fatty acid content, three different prey supply intervals (daily, once every 2 d, and once for 4 d) were tested. Daily prey supply yielded the highest total fatty acid and DHA contents in G. smaydae. Furthermore, we successfully produced high-density G. smaydae cultures semi-continuously for 43 d with daily prey supply. During the semi-continuous cultivation period, the highest density of G. smaydae was 57,000 cells mL^-1, with an average growth rate of 0.7 d^-1. Taken together, the percentage of EPA and DHA in the total fatty acid content was maintained in the range of 54.2-56.9%. The results of this study support G. smaydae as a promising microalgal candidate for commercial DHA production and demonstrate that daily supply of prey can efficiently produce high-density G. smaydae cultures for more than a month.

• Journal of Nutrition and Health
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• v.29 no.2
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• pp.213-222
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• 1996

The most abundant long-chain polyunsaturated fatty acid in brain lipids is docosahexaenoic acid(C22 : 6 N-3, DHA). It is incorporated into nerve tissues mostly in utero and during the first year of life. DHA in brain is derived from either pre-formed DHA in human milk or by infant hepatic synthesis from linolenic acid in milk. This study was designed to investigate the effects of DHA supplementation on fatty acid profiles in maternal plasma lipid and breast milk. Twenty lactating women participated in the study. Seven women took 3g of fish oil per day and vitamin E for 28 days starting from the day of giving birth. Five women consumed 1.5g of fish oil as well as tivamin E, and the rest took vitamin E supplements for the same period of time. Dietary questionnaires and 3 consecutive 24-h recalls were collected to evaluate theri nutritional status and food habits. Finding that DHA intake from fish was not significantly different among three experimental groups, the partcipants were instructed to continue eating their usual home diets. Milk samples were taken on the day of giving birth, as well as the 7th, 14th and 28th day being the supplement phase, and finally 2 weeks after the cessating of DHA supplements. The amounts of the fish oil supplements produced significant dose-dependent increased in the DHA content of milk and plasma, but to a lesser degree. Base-line for 28 days raised the level to 2.05$\pm$0.43% and 1.5g/day supplement produced DHA levels of 1.02$\pm$0.19%. The results of this study indicated that relatively small amount of dietary DHA supplementation significantly elevats DHA content in milk. This would clearly elevate the infant's DHA intake which in turn may have implications for the infant's brain development.

• Journal of Life Science
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• v.9 no.4
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• pp.493-495
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• 1999

Eicosapentaenoic (EPA, 20:5) and docosahexaenoic (DHA, 22:6) acids of gull eggs were analyzed and the results are summarized as follows: 1. EPA and DHA were 2.25% and 4.35% in the total fatty acid of gull eggs. 2. Triglyceride fractions in the fatty acids had 0.56% in EPA and 1.59% DHA. 3. Diglyceride fractions contained 1.10% EPA and 1.97% DHA. 4. Phospholipid fractions had the most abundant amounts of 4.26% EPA and 8.13% DHA.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.7
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• pp.1047-1053
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• 2006

The current study was designed to determine the effects of dietary docosahexaenoic acid (DHA) on fatty acid deposition in egg yolk and various tissues of laying Tsaiya ducks, and on the mRNA concentrations of hepatic lipogenesis-related transcription factors. Thirty laying ducks were randomly assigned to three treatments with diets based on corn-soybean meal (ME: 2803 kcal/kg; CP: 17.1%; Ca: 3.4%) supplemented with 0% (control diet), 0.5% or 2% algal DHA oil. The DHA content in egg yolks of the ducks was elevated significantly (p<0.01) with the supplementation of dietary DHA. The DHA percentage of the total fatty acids in the egg yolk of laying ducks was 0.5%, 1.3% and 3.4% for 0%, 0.5% and 2% algal DHA oil treatments, respectively, for the $1^{st}$ week, and 0.5%, 1.5% and 3.3% for the $2^{nd}$ week. Therefore, algal DHA oil can be utilized by laying Tsaiya ducks to enhance the egg-yolk DHA content. The concentrations of triacylglycerol (TG) and cholesterol in plasma of laying Tsaiya ducks were not affected by dietary DHA treatments (p>0.05). The DHA concentration in plasma, liver, and skeletal muscle was increased with the addition of dietary algal DHA oil (p<0.05). The mRNA abundance of sterol regulatory element binding protein 1 (SREBP1) and SREBP2 in the livers of laying Tsaiya ducks was not affected by dietary DHA, suggesting that the expression of these transcription factors is tightly controlled and not sensitive to DHA treatments.