Spermine, Choline, Ergothioneine 173 



choline deficiency those concerned with reproduction are particu- 

 larly striking; choline is known, for example, to be essential for egg 

 production in the chicken, as well as for normal lactation and 

 nutrition in rats. 



The role of choline in transmethylations is linked with the 

 presence of the trimethyl quaternary nitrogen. It is worth noting, how- 

 ever, that while the phenomenon of transmethylation is common 

 to a whole group of compounds bearing labile methyl groups, 

 the lipotropic activity is restricted to choline and a few closely 

 related derivatives. One of the lipotropically active derivatives is 

 phosphorylcholine (Welch and Welch, 1938), and there is some 

 evidence that the incorporation of choline into phospholipids pro- 

 ceeds via phosphorylcholine (Wittenberg and Kornberg, 1953). 



A further possibility regarding the function of choline in semen 

 comes to mind; choline and its derivatives belong to a group of sub- 

 stances endowed with well-defined pharmacological properties, and 

 it is not improbable that the base itself or one of its compounds may 

 exert some pharmacodynamic effects either on the spermatozoa or, 

 perhaps, on some parts of the male or female reproductive tract. 

 When assayed by Goldblatt (1935^) on the m. rectus abdominis of 

 the frog, 1 ml. human seminal plasma exhibited roughly the same 

 activity as l^g. acetylcholine. There is, however, no chemical evi- 

 dence to show that the substance in seminal plasma, responsible 

 for this activity is in fact, acetylcholine. 



Choline esterase 



It has been claimed that sperm motility is somewhat increased 

 by acetylcholine, and depressed by eserine, but this effect has never 

 been analysed quantitatively and requires confirmation. There is, 

 on the other hand, sufficient evidence to show that semen contains 

 choline esterase as a normal constituent. In human semen, the con- 

 centration of choline esterase was found to be low. Zeller and Joel 

 (1941) using the manometric method, and employing a rather high 

 concentration of acetylcholine as substrate, found that the quantity 

 of acetic acid liberated by 1 ml. semen in 1 hr. is equivalent to not 

 more than 70 [A. CO2, as compared with 3600 /td. in blood serum 

 and 38000 /tl. in brain; moreover, the bulk of activity was derived 

 from the seminal plasma and not from the spermatozoa. Boar 



