RETROCONVERSION OF DHA IN LIVE FOOD

研究了在活体食品中，尤其是卤虫无节幼体中，二十二碳六烯酸(DHA)能否反转化为二十二碳五烯酸(DPA)或二十碳五烯酸(EPA)。第一年，用DHA直接法富集卤虫。在卤虫培养基中添加EPA后，卤虫体内的EPA含量增加，但未检测到DPA和DHA。在富含DHA的卤虫中，DHA的含量增加，DPA的含量很少。此外，与富含油酸(不含n-3脂肪酸)的卤虫相比，其EPA含量的增加幅度更大。另一方面，富含DHA的卤虫体内的DHA含量不到富含EPA的卤虫EPA含量的一半。这一结果表明，卤虫体内DHA可能转化为DPA和EPA。为了证明从DHA到DPA的转化，这是逆向转化的第一步，[1-^&lt；14&gt；C]DHA被直接浓缩到卤虫中。结果表明，利用高效液相色谱技术，DPA组分中有少量的放射性摄取。在第二年，还表明培养温度可能会改变DHA逆转化的比例。在16和25ﾟC的实验温度范围内，卤虫对DHA的吸收保持在16ﾟC和25ﾟC下6h，结果表明，在恒温条件下，卤虫对DHA的吸收没有明显的差异，但在随温度变化的范围内，放射性吸收增加了30%。这说明温度对卤虫体内脂肪酸的积累有影响。结果表明，卤虫体内存在DHA向EPA的逆转录途径，卤虫以DHA为能源，DHA在卤虫体内不易积累。

The study was investigated whether docosahexaenoic acid (DHA) can be retroconverted to docosapentaenoic acid (DPA) or eicosapentaenoic aicd (EPA) in live food, especially Artemia nauplii. In the first year, Artemia was enriched with DHA in dilrect method. When EPA was supplemented to Artemia medium, the content of EPA in Artemia increased, but DPA and DHA were not detected. In DHA-enriched Artemia, the DHA content was increased, and DPA was detected a little. Furthermore, the EPA content was increased more than that in Artemia enriched with oleic acid (containing no n-3 fatty acids). On the other hand, the DHA content in DHA-enriched Artemia accumulated less than half of the EPA content in EPA content in EPA-enriched Artemia. This result indicated that DHA might be converted to DPA and EPA in Artemia. In order to prove the conversion from DHA to DPA, which is the first step of retroconversion, [1-^<14>C] DHA was enriched directly to Artemia. The result showed that the radioactivity uptake was slightly observed in the DPA fraction by using HPLC technique. In the second year, it was also indicated that the cultural temperature may change the proportion of DHA retroconversion. DHA uptake in Artemia was examined in the experimental range maintained at 16 and 25ﾟC and the range maintained at 16ﾟC for 6h and changed to 25ﾟC As a result, a large difference in DHA uptake was not observed in the isothermal temperature, but in the range with the temperature change radioactive uptake was increased by 30%. This shows that temperature affect on the accumulation of fatty acids in Artemia. It is suggested that Artemia has retrocovert pathway from DHA to EPA, and Artemia use DHA as energy sources, so DHA is hard to accumulate in Artemia.