380 VIII. CHOLESTEROL AND RELATED STEROLS 



tene); introduction of a second alcohol group (7-hydroxycholesterol) ; 

 esterification of the alcohol group (7-hydroxycholesteryl dibenzoate) ; 

 and the introduction of a ketone group on Cy (7-ketocholesteryl acetate) . 



Both cholesterol and ergosterol were found by Chauvin^^* to serve equally 

 satisfactorily as sources of sterols in two species of Orthoptera or wingless in- 

 sects. Thus, these sterols acted as growth factors for Gryllus domesticus 

 (house cricket) and Blatella germanica L. (German cockroach, croton bug) ; 

 in the case of the latter species, the dietary sterols exerted an effect on re- 

 production. Yeast was found to be incapable of supplying a sufficient 

 quantity of the sterols. More recently, Noland''^^ demonstrated that, in 

 the German cockroach, a linear growth response to dietary cholesterol in 

 the range to 0.05 per cent of the diet may be observed. In a systematic 

 study of the effect of structm-al alterations of the molecule, as exemplified 

 in forty-one sterol derivatives, it was found that the hydroxyl group on 

 carbon 3 was essential, either in free or in esterified form, while the double 

 bond between carbons 6 and 6 was not required. Minor changes in the 

 nucleus or side chain had relati^Tly lesser effects on growth. Cholesteryl 

 chloride exhibited an ad\'erse effect on growth, which could be o^-ercome by 

 an excess of cholesterol. Cailleau"* reported that cholesterol is a required 

 dietary component for certain parasitic flagellate protozoa: Trichomonas 

 columbae, Avhich is found in birds affected with diphtheria, T. foetus, from 

 the genital tract of cattle, and Eutrichomasiix colubrarum, an intestinal 

 parasite isolated by Cailleau from the blood of the gecko, or wall lizard 

 (Lacerta muralis, of the Geckonidae family). 



{2) Acetate as a Source of Cholesterol 



Bloch and Rittenberg'^^ were the first to demonstrate the conversion of 

 deuterioacetate into deuteriocholesterol in mice and rats. The impor- 

 tance of acetate as a building stone for the cholesterol molecule is indicated 

 by the fact that the tagged portions of the acetate were found not only in 

 the side-chain but also in the steroid nucleus. On the basis of these data, 

 it was postulated that acetic acid pro\ddes a fundamental unit in choles- 

 terol synthesis in the body. In later studies by Bloch and Rittenberg,"^"* 



1" R. Chauvin, Compt. rend., 229, 902-903 (1949). 

 "* J. L. Noland, Arch. Biochem. Biophys., 48, 370-379 (1954). 

 1" R. Cailleau, Ann. inst. Pasteur, 59, 137-172 (1937). 



"6K. Bloch and E. Rittenberg, J. Biol. Chem., US, 297-298 (1942); US, 625-636 

 (1942). 



1" K. Bloch and D. Rittenberg, /. Biol. Chem., 159, 45-58 (1945). 

 "8 D. Rittenberg and K. Bloch, /. Biol. Chem., 160, 417-424 (1945). 



