The Characterization of the Plasma Lipoproteins of the Channel Catfish Ictalurus punctatus

• Published in: Physiological zoology 1985-11, Vol.58 (6), p.693-704
• Main Authors: McKay, M. Craig, Lee, Richard F., Smith, M. A. K.
• Format: Article
• Language: English
• Subjects: biochemical composition; Biological and medical sciences; blood; Blood plasma; Catfish; Fatty acids; Freshwater; Fundamental and applied biological sciences. Psychology; Gels; HDL lipoproteins; Ictalurus punctatus; Lipids; Lipids. Glycolipids; Lipoproteins; Metabolisms and neurohumoral controls; Phospholipids; plasma; Plasma density; Triglycerides; Vertebrates: anatomy and physiology, studies on body, several organs or systems
• ISSN: 0031-935X
• DOI: 10.1086/physzool.58.6.30156073

The plasma lipoproteins of the channel catfish were separated by ultracentrifugation into very low-density lipoproteins (VLDL), low-density lipoproteins (LDL), and highdensity lipoproteins (HDL), using the same density intervals employed to separate their human counterparts. Serum background density, ultracentrifugal flotation, and electrophoretic behavior of native catfish and human lipoproteins were comparable. In well-fed catfish the lipoproteins accounted for almost 30% of the total plasma protein and 95% of the total plasma lipid. The HDL was the major lipoprotein, containing 84% of the protein and 5% of the lipid in the plasma fraction d < 1.21 g/ml. Comparison of fed and fasted catfish showed the levels of VLDL and LDL to be closely correlated with the intake of dietary lipid, while the level of HDL was not. Fatty acid composition of the lipoproteins was similar to that reported for other fish species. Cholesterol esters had a high proportion of polyunsaturated fatty acids with 22:6ω3 accounting for between 14% and 27% of the fatty acids. Analysis of the apoproteins by electrophoresis in sodium dodecyl sulfate (SDS) or 8 M urea showed that there is a characteristic apoprotein content associated with each lipoprotein class. The major component of both apoVLDL and apoLDL was a peptide with a molecular weight of 250,000 daltons with properties similar to the apoB protein found in mammals. Catfish apoHDL showed six major bands on SDS gel electrophoresis with molecular weights of 11,000, 22,000, 25,500, 106,000, 128,500, and 159,000 daltons.