Originally published in Biochem. J. 44, 407 (1949). 



94. ZINC UPTAKE BY NEUROSPORA 



Irma Andersson-Kotto and G. Hevesy 



From Wenner Gren Institute and the Institute for Research in Organic Chemistry, 



University of Stockholm 



Among the minor constituents of living tissues zinc is one of great 

 interest (see Lehman, 1939; Broh-Kahn and Mirsky, 1948; War- 

 burg, 1948; Bertrand, 1948). It constitutes 0.33% of carbonic anhyd- 

 rase (Keilin and Mann, 1940), and it is a constituent of uricase which 

 contains 1.3% of zinc (Davidson, 1938; Holmberg, 1939) and possibly 

 of other enzymes. It was found to be essential for growth and citric acid 

 formation of Aspergillus niger (Bernhauer, 1928), for growth and 

 fumaric acid production of Rhizopus nigricans (Foster and Waksman, 

 1939) and for growth and subtilin formation by Bacillus suhtilis (Feeney, 

 LiGHTBODY and Garibaldi, 1947). 



The presence of 0.2 mgm of zinc in the food of mice is stated by Beri- 

 RAND (1948) to prolong the life of the animals from 2 — 3 weeks to 

 2—2.5 months. 



Wassiljew (1935) demonstrated that the effect of zinc was not the 

 same for biochemically different strains of A. niger, and he went so far 

 as to suggest a characterization of A. niger strains based on their reacti- 

 vity to zinc. Foster and Waksman (1939) interpret the function of 

 zinc as catalysing a more complete destruction of the glucose molecule 

 with a consequent greater efficiency of energy utilization by the fungus. 



In connexion with studies on the gowth of Neurospora crassa we 

 determined the amount of zinc necessary to obtain a maximum growth 

 of that mould. 



METHODS 



Throughout the experiments mycelium from one spore was used. This was 

 produced by crossing the two wild-type strains, nos. 25o and lA of Beadle (1946). 

 The culture solution was that described by Ryan, Beadle and Tatum (1943); 

 it was autoclaved, and the cultures were treated under sterile conditions. Inocula 

 were taken from cultures 4 — 5 days old. 



Labelled zinc as chloride and varying amounts of non-radiaoactive zinc as 

 sulphate were added to culture solutions at the start of the experiments. From 



