HYDROCARBONS 323 



squalene plays a role in embryologio development. According to Chan- 

 non,'^^ the presence of squalene is largely limited to Squalidae; this worker 

 recorded its occurrence in three of five species examined, but noted that it 

 was not present in eleven different elasmobranch families, in fourteen 

 species of teleostid fishes, or in any of a number of phyto- or zooplanktons 

 examined. Andre and Bloch'*" observed that the liver oil of the shark, 

 "Darkie Alf" (Dalatias licha) contained as much as 57% of squalene, as 

 compared with a total glyceride content of only 21.7% and a glyceryl ether 

 percentage of 21.3%. Bloor^^ suggested that, in the case of the shark 

 li^'er oils, squalene replaces the unsaturated fatty acids. Squalene has 

 likewise been reported to be a component of the sebum of man,'^' where it 

 is being constantly excreted, together with cholesterol and traces of fatty 

 acids. According to Wheatley,^^^ squalene may be present to the extent 

 of 5% in human forearm sebum. 



In addition to animal fats, at least two plant fats have been reported to 

 contain squalene. Thus, Thorbjarnarson and Drummond^^' found it in 

 various olive oils; the non-saponifiable extract of Palestinian, Tunisian, 

 Spanish, and Turkish olive oils contained 64, 38, 31, and 58% of this 

 hydrocarbon, respectively. Although no significant amount of squalene 

 could be demonstrated in teaseed oil,'^^ Taufel and co-workers'^^ recorded 

 that squalene comprises 16% of yeast fat. 



The importance of squalene in intermediary metabolism has recently 

 been emphasized by the suggestion that it participates in cholesterol s}^!- 

 thesis. Considerable difficulty exists in establishing the intermediate 

 position, inasmuch as the metabolic turnover is very rapid. The maximum 

 acetate carbon is incorporated into squalene in thirty minutes. '^^ Langdon 

 and Bloch'^' fomid that, when labeled acetate was administered together 

 with natural squalene, the recovered squalene was partially radioactive. 

 When labeled C'^-squalene prepared biosynthetically from acetate was 

 administered to mice, it was found to be efficiently converted to choles- 



i« H. J. Channon, Biochem. J., 22, 51-59 (1928). 



ISO E. Andre and A. Bloch, Bull. soc. chim. [5], 2, 789-802 (1935); Compt. rend., 196, 

 618-620(1933). 



'" R. M. B. MacKenna, V. R. Wheatley, and A. Wormall, J . Investigative Dermatol., 

 75,33-47(1950). 



'** V. R. Wheatley, Livre juhilaire, 1901-1951, de la Societe beige de Dermatologie et de 

 Syphilographie, Brussels, 1952, pp. 91-103; cited by R. P. Cook, Comparative Aspects of 

 Lipid Absorption and Excretion, in R. T. Williams, Lipid Metabolism, Biochem. Soc. 

 Symposia, No. 9, 14-29 (1952). 



1" T. Thorbjarnarson and J. C. Drummond, Analyst, 60, 23-29 (1935). 



•" K. Taufel, H. Thaler, and H. S. Shreyegg, Z. Untersuch. Lebensm., 72, 394-404 

 (1936). 



i« R. G. Langdon and K. Bloch, /. Biol. Chem., 200, 129-134 (1953). 



