Conversion of 5α-Cholestan-3β-ol to Δ7-5α-Cholesten-3β-ol in Cockroaches

Detailed studies of the sterol requirement of the carnivorous beetle Dermestes vulpinus (1) which have been carried out in this laboratory have indicated that up to 97% of the normal dietary cholesterol requirement of this insect may be replaced by a number of other sterols.One of the compounds capable of sparing but not completely replacing cholesterol in the diet of these insects is cholestanol.1In an attempt to analyze the significance of this sparing effect, we have studied the same phenomenon in the cockroach Eurycotis &r&ma.This insect may be reared aseptically on a synthetic diet that cont.ainseither 0.1 y0 cholesterol alone or 0.1 y0 cholestanol together with 0.00570 cholesterol but will not grow when fed a diet containing cholestanol alone except under nonsterile conditions.2In an earlier report (2), it was shown that the tissues of Eurycotis reared aseptically on a diet containing 0.1% cholestanol-7cu-H3 and 0.005 7O cholesterol-4-C14 contained cholesterol-4-Cl4 and at least one tritium-labeled sterol which, however, was not identified.In this paper, evidence for the metabolic conversion of cholestanol to A7-cholestenol in these insects will be given.A preliminary report of this work has been presented (3), and findings similar to our own have been reported more recently by Louloudes, Thompson, Monroe, and Robbins (4).EXPERIMENTAL PROCEDURE Cockroaches-Eurycotis jlmiclana and Blattella germanica were descendants of stock colonies, kindly provided by Dr. Louis Roth of the United States Army Quartermaster Research Laboratories,