Amino Acids and Lipids of the Plasma HDL from the White Shrimp Penaeus vannamei Boone

Abstract

Studies about lipids are taking importance in shrimp, due to their physiological role in nutrition, development and reproduction. These molecules are mobilized through hemolymph by lipoproteins. A 98 kDa high density lipoprotein (HDL) has been detected in shrimp plasma and it is non–sex-associated, since it is present in both, male and female juvenile shrimp. The HDL was purified by density gradient ultracentrifugation from the hemolymph of juvenile white shrimp Penaeus vannamei males and females, separately; and the protein and lipid moieties studied. The amino acid composition and the N-terminal sequence for 15 residues of the 98 kDa apolipoprotein were determined. In addition, the plasma lipid components from male and female were detected by TLC, identifying phospholipids, sterols, and acylglycerols. The lipid concentration of plasma and purified HDL were determined by enzymatic assays, quantifying phosphatidyl choline, acylglycerols, free fatty acids and sterols. Similar concentrations of the lipid classes were found in male and female HDL confirming its sex independence. Purified HDL contains approximately 50% lipids, where the major components are phospholipids followed by acylglycerols, sterols, and free fatty acids. Considering that the HDL plasma concentration is approximately 2% of total protein, HDL could be the major lipid-transporting molecule in shrimp.