Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Enrichment of Artemia with free methionine.

Abstract

Different enrichment procedures of the free amino acid (FAA) methionine were tested for Artemia nauplii. A direct enrichment protocol (methionine dissolved in the culture water) was compared with liposome enrichment protocols that varied in their membrane composition. During 16 h of direct enrichment in 5.3 msmallcap˜M methionine, the nauplii increased their content of free methionine between 20- and 30-times compared to the unenriched control (43.1±1.2 and 68.4±3.8 pmol/nauplius in 2 experiments vs. 2.4±1.0 pmol/nauplius in control). However, by encapsulating the identical amount of methionine into liposomes made from pure egg yolk phosphatidylcholine (PC) (>99% PC) and cholesterol, the nauplii content of free methionine reached 148.8±27.6 pmol/nauplius, which was approximately 60-times more than in the unenriched control. Another liposome composition tested, made from crude egg yolk PC (>60% PC) and cholesterol, resulted in 90.5±4.1 pmol/nauplius. The enriched nauplii still retained 80% of the free methionine after 8 h of incubation at conditions simulating feeding for Atlantic halibut larvae (13°C, 33.5 g/litre). In conclusion: (1) Artemia nauplii can successfully be enriched with free methionine, (2) the high retention of free methionine in the Artemia nauplii following transfer to fish tanks shows that it is possible to offer fish larvae a feed with a high level of FAA, based on enrichment of Artemia nauplii.