Westergaard M & Mitchell H K. Neurospora V. a Synthetic Medium
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CC/NUMBER 22 JUNE 1,1981 This Week's Citation Classic Westergaard M & Mitchell H K. Neurospora V. A synthetic medium favoring sexual reproduction. Amer. J. Bot. 34:573-7, 1947. [Kerckhoff Labs, of Biology, California Institute of Technology, Pasadena, CA] In the early years of Neurospora nist-geneticist-cytologist and most genetics, crosses were made mostly other things in biology which I was on 'corn meal agar' where growth not. In fact, virtually all of my time was poor and ascospore produc- during this period was spent with tion often erratic. Described in this Neurospora mutants in isolation, paper is a synthetic medium which identification, and synthesis of supports prolific production of sex- ual spores as well as good growth. metabolic intermediates in the [The SCI® indicates that this paper biosynthesis of purine, pyrimi- has been cited over 355 times since dines, and various amino acids. So 1961.] when Mogens asked the question of why sexual reproduction of Neurospora only occurred on a medium which gave poor growth, I was not particularly interested. Herschel K. Mitchell However, I had previously been in- Division of Biology volved with the isolation of growth California Institute of Technology factors for neuroorganisms (panto- Pasadena, CA 91125 thenic acid and folic acid) and it seemed possible that there might be something of the sort involved May 4, 1981 in this situation. But we were reasonably sensible from the be- "Sexual spores of Neurospora ginning and simply rearranged the are rugged and resistant to environ- concentrations of the constituents mental stresses. In fact they re- of the standard synthetic medium quire a heatshock of some 60°C to which would yield good growth. become activated for germination. "That was in fact all there was to Therefore, it seemed logical to it. When the mold is required to some to believe that sexual repro- reduce nitrate for a nitrogen duction in the fungus might be in- source both sexual reproduction duced by starvation conditions in and good growth can be obtained. anticipation of harder times to There remain some interesting come: at least that is the way the questions of shifts in metabolic story was told. The 'anticipation' balances which have not been an- was always a bit bothersome but I swered so far as I know, but the had no particular urge to in- medium we devised worked well vestigate the question until the ap- for genetics. Improvements were pearance here at the California In- not really necessary so the original stitute of Technology of the late has been referenced for quite some Mogens Westergaard from the Ge- time now. It is simple and it still netics Institute of the University of works, thus accounting for the arti- Copenhagen. Mogens was a bota- cle's frequent citation." .