The accumulation and metabolism of astaxanthin in Scenedesmus obliquus (chlorophyceae)

The biosynthesis and metabolism of astaxanthin in coenobium alga Scenedesmus obliquus were investigated using a two-stage culture. The first stage was for the analysis of biosynthesis and accumulation of astaxanthin in alga cells which were cultured under induction conditions (incubation at 30 degrees C and illumination of 180 mu mol m(-2) s(-1)) for 48 h. The composition of the secondary carotenoids in algal cells was analyzed and seven ketocarotenoids were identified. The results implied that S. obliquus synthesized astaxanthin from beta-carotene through three possible pathways. In the second stage, the cultures were transferred to normal conditions (incubation at 25 C and illumination of 80 mu mol m(-2) s(-1)) for 72 h. Algal cells accumulated more chlorophyll and biosynthesis of secondary carotenoids terminated, the content of secondary carotenoids decreased from 59.48 to 6.57%. The results inferred that accumulation and metabolism of astaxanthin could be controlled by cultivated conditions which also could lead the mobilization of secondary carotenoids to support the algal cell growth. The results also implied that presumed conversions from astaxanthin to lutein or antheraxanthin could be modulated by culturing conditions. (C) 2008 Published by Elsevier Ltd.

Effect of dietary supplementation of vitamins A, D-3, E, and C on yearling rice field eel, Monopterus albus: Serum indices, gonad development, and metabolism of calcium and phosphorus

The objective of this study was to determine the effect of dietary vitamins A, D-3, E, and C on the gonad development, lipid peroxidation, and immune response of yearling rice field eel, Monopterus albus. A 6-wk feeding trial was designed according to an L-16(4(5)) orthogonal design, in which four vitamins, each at four supplementation levels, were arranged. Sixteen diets were mixed with the different vitamin levels and randomly assigned to 16 groups of fish. Increasing dietary vitamin E supplementation level significantly (P <= 0.05) increased the gonadosomatic index and lowered the serum content of malondialdehyde of rice field eel. Increasing dietary vitamin A and C levels also showed similar effect, but the differences were not statistically significant. Serum immunoglobulin M content increased significantly (P <= 0.01) as dietary vitamin C supplementation levels increased. The concentrations of calcium in bones showed significant (P <= 0.05) trend with vitamin D-3 and A supplementation levels, but the bone phosphorus content was not affected by the dietary vitamin levels.