Waste nitrogen metabolism and excretion in zebrafish embryos: effects of light, ammonia, and nicotinamide

摘要: Bony fish primarily excrete ammonia as adults however the persistence of urea cycle genes may reflect a beneficial role for production during embryonic stages in protecting embryo from toxic effects produced highly nitrogenous yolk. This study aimed to examine dynamic scope changes rates synthesis and excretion one such species (zebrafish, Danio rerio) by manipulating intrinsic developmental rate (by alteration light:dark cycles), well direct chemical manipulation via injection (to potentially activate production) nicotinamide exposure inhibit production). Continuous dark delayed development embryos evidenced appearance hallmark anatomical features (heartbeat, eye pigmentation, body lateral line, fin buds) at 30 48 hr post-fertilization, lower hatching compared reared continuous light. Both were similarly effected generally higher continuously exposed Ammonia resulted significant increases (up fourfold) N no along with modest yolk content 2-6 post-injection. Nicotinamide (an inhibitor mammals) reduced ammonia-induced increase led retention embryo. Our results indicate that there is relatively rapid large production/excretion developing embryos. Potential mechanisms these are discussed.