Changes of retinoid contents in larval Japanese flounder Paralichthys olivaceus and Artemia nauplii enriched with a large dose of all-trans retinoic acid

ABSTRACT:   The present study examined the changes of retinoid content in larval Japanese flounder Paralichthys olivaceus and Artemia nauplii. Artemia nauplii were enriched with 100 mg all-trans retinoic acid (atRA) for 6 h in a 10-L culture tank and then starved for the next 24 h. Flounder larvae at the G stage were fed Artemia nauplii enriched with atRA and then starved for the next 24 h. They were sampled at −6 h (before enrichment), and at 0, 6, 9, 18 and 24 h after enrichment for analysis of three isomers of retinoic acid (atRA, 9 cis- and 13 cis retinoic acid), retinol, retinal, and retinyl palimitate. atRA was rapidly accumulated in Artemia without isomerization. Peaks of atRA and retinyl palmitate levels were observed at 6 and 18 h in Artemia, suggesting that Artemia excrete RA metabolites and re-uptake in the tank without water exchange. atRA levels in flounder reached a maximum level at 3 h after feeding and decrease to 50% of the maximum level within 18 h, suggesting that flounder larvae can rapidly excrete dietary atRA.