The biosynthesis, absorption, and origin of cholesterol and plant sterols in the Florida land crab.

T S Douglass,W E Connor,D S Lin

doi:10.1016/s0022-2275(20)37334-x

Abstract

In order to study the biosynthesis, composition, and origin of sterols in the Florida land crabs, Cardisoma guanhumi (Latreille), we fed 17 male crabs either a cholesterol-free or a high cholesterol diet for 2 to 7 weeks. The origin of sterols in these crabs, whether from biosynthesis or from the diet, was determined by tahree procedures: the incorporation of isotopic mevalonate into the cholesterol when the diet was cholesterol-free; the absorption of isotopic cholesterol and sitosterol from the diet; the cholesterol and plant sterol concentrations of hepatopancreas, plasma, and muscle under conditions of cholesterol-free and high cholesterol diets. In addition, the interconversion of cholesterol and sitosterol was investigated. Dietary sterols of plant and animal sources were readily absorbed and provided the major source of sterols for this species of crab. The biosynthesis of cholesterol from mevalonate in this crab was minimal. However, cholesterol was synthesized from dietary sitosterol by dealkylation. Cholesterol and the three plant sterols (24 epsilon-methyl cholesterol, stigmasterol, and sitosterol) were found in the hepatopancreas, plasma, and muscle of the crab. Plant sterols contributed from 9 to 37% of the total sterols in the hepatopancreas, plasma, and muscle of the crabs fed a cholesterol-free diet.

Highlights

I n order to study the biosynthesis, composition, and origin of sterols in the Florida land crabs, Cardisoma panhumi (Latreille), we fed 17 male crabs either a cholesterol-free o r a high cholesterol diet for 2 to 7 weeks
All experiments to date investigating the possibility of sterol biosynthesis in crustaceans have utilized animals either fasted or fed a diet containing cholesterol
No experiments have been performed using animals fed very low cholesterol diets. Since both the fasting state [5,6,7] and dietary cholesterol [8,9]inhibit cholesterol synthesis in vertebrates, the same considerations might apply to crustaceans and, could explain the past failures to demonstrate cholesterol biosynthesis

Summary

Introduction

I n order to study the biosynthesis, composition, and origin of sterols in the Florida land crabs, Cardisoma panhumi (Latreille), we fed 17 male crabs either a cholesterol-free o r a high cholesterol diet for 2 to 7 weeks. All experiments to date investigating the possibility of sterol biosynthesis in crustaceans have utilized animals either fasted or fed a diet containing cholesterol. No experiments have been performed using animals fed very low cholesterol diets Since both the fasting state [5,6,7] and dietary cholesterol [8,9]inhibit cholesterol synthesis in vertebrates, the same considerations might apply to crustaceans and, could explain the past failures to demonstrate cholesterol biosynthesis. The design of the experiment to be reported was to study the biosynthesis of cholesterol in Florida land crabs, Cardisoma guanhumi (Latreille), fed a cholesterol-free diet to obviate the problems from fasting and from the ingestion of dietary cholesterol. The absorption of dietary cholesterol and plant sterols and their interconversion were investigated [2]

Methods

Results

Conclusion