REQUIREMENTS OF INSECTS 



A clearer understanding of the biosynthesis of choline was obtained 

 with the aid of mutants of Netirospora crassa, one of which has already 

 been mentioned as having been used for the microbiological assay of 

 choline (page 587). These cholineless mutants of N. crassa, although 

 able to synthesise the methyl donator, methionine, were unable to 

 synthesise the methyl acceptor, dimethylaminoethanol.^ 



Mutant 47904 produced a substance which was identified as mono- 

 methylaminoethanol ; this replaced choline for another strain, 34486.'* 

 It was concluded that strain 47904 was unable to convert methyl- 

 aminoethanol into choline, whereas in strain 34486 the synthesis of 

 choline was blocked prior to the formation of methylaminoethanol, 

 probably at the stage involving the formation of this substance from 

 aminoethanol. 



References to Section 11 



1. E. Badger, /. Biol Chem., 1944, 153, 183 ; /• Bact., 1944. 47, 



509. 



2. C. Lamanna and C. Lewis, ibid., 1946, 51, 398. 



3. T. H. Jukes and A. C. Dombush, Proc. Soc. Exp. Biol. Med., 1945. 



58, 142. 



4. N. H. Horowitz, /. Biol. Chem., 1946, 162, 413. 



12. CHOLINE REQUIREMENTS OF INSECTS 



Choline was essential for the growth of larvae of Ptinus tectus and 

 Lasioderma serricorne, but not of the larvae of Tribolium confusum and 

 Sitodrepa panicea under ordinary conditions.^ When the larvae of 

 the last-named beetle were sterilised, however, choline had to be 

 added to the diet in order for growth to continue, so that this 

 insect, and possibly also Lasioderma, contains symbionts that syn- 

 thesise choline. 



The cockroach, Blattella germanica, also required choline for growth. ^ 

 This could not be replaced by either aminoethanol or methylamino- 

 ethanol, but the addition of methionine, dimethylaminoethanol and 

 betaine in that order stimulated growth on a choline-deficient diet. 

 Insects fed betaine contained nearly as much choline as those fed an 

 equivalent amount of choline. 



References to Section 12 



1. G. Fraenkel and M. Blewett, Nature, 1943, 151, 703 ; 1943, 152, 



506 ; Biochem. J., 1943, 37, 686 ; Proc. Roy. Soc, 1944, 132, 

 212. 



2. J. L. Noland and C. A. Baumann, Proc. Soc. Exp. Biol. Med., 



1949. 70, 198. 



597 



