Lipid and fatty acid composition and energy partitioning during embryo development in the shrimp Macrobrachium borellii

Energy partitioning, composition of lipids and fatty acids, and their utili zation by embryos were determined in the lecithotrophic shrimp Macrobrachiu m borellii during seven development stages. The biochemical composition at stage I is represented by lipids, proteins, and carbohydrates, with 29.3, 2 8.7, and 0.2% dry weight, respectively. The former two were identified as t he major energy-providing components, contributing 131 and 60 caI/100 mg eg g, dry weight, respectively. The overall conversion efficiency (CE) was 45. 0% (calculated as percentage of vitelline energy transformed into embryonic tissues). Lipids were the most important energy reserve (CE 39.3%), follow ed by proteins (CE 57.1%), both being simultaneously utilized during develo pment while carbohydrates were synthesized de novo (CE 587.5%). Variation i n the lipid class composition of embryos and vitellus showed an accumulatio n of triacylglycerols (TAG) and phospholipids (PL) up to stage IV, a more a ctive accumulation and selective utilization phase (stages V and VI), and a consumption and de novo synthesis period until hatching. Structural lipids (PL and cholesterol) and pigment astaxanthin were selectively conserved in embryos, but TAG, hydrocarbons, and esterified sterols were preferentially depleted. Monounsaturated fatty acids (FA) were the major group in TAG, wh ereas polyunsaturated FA (PUFA) were the major group in PL after organogene sis. Certain PUFA such as 22:6n-3 and 20:5n-3 were selectively accumulated in FL.