Long-chain polyunsaturated fatty acids enhance the formation of rotifer dormant encysted embryos†

This study uncovers the critical role of dietary n-3 polyunsaturated fatty acids (PUFAs) in the development of dormant embryos, known as resting eggs (REs), in the aquatic rotifer Brachionus plicatilis. REs contained PUFAs, and the maternal diet markedly influenced their levels. In this respect, supplementing PUFAs-deficient yeast with eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) in the diet increased RE production. A combination of EPA and DHA yielded the highest number of produced REs and reduced the percentage of damaged REs, without altering hatching rates. Proteome profiling investigated the impact of EPA and DHA on protein expression patterns. It identified 283 differentially expressed proteins out of 1954 and indicated distinct EPA and DHA functions. Differentially expressed proteins were linked to multiple functional pathways, suggesting nuclear receptor regulation. In vertebrates, EPA, DHA, and α-linolenic acid (ALA) interact with retinoid and peroxisome proliferator-activated receptors. These receptors emerged as promising regulators in PUFAs-treated rotifers. Consequently, the impact of ALA was also assessed. Remarkably, ALA enhanced reproductive rates, increased RE production, reduced the proportion of damaged REs, and improved hatching in a dose-dependent manner, even in the absence of EPA and DHA. These findings emphasize the essential roles of PUFAs in rotifer RE formation, a previously unexplored topic. The study stresses the need to investigate the roles of PUFAs during dormancy. This is important because global warming may reduce the availability of PUFAs, decrease the quantity of REs in egg banks, and affect the long-term viability of aquatic non-vertebrate populations.