Genetic Control of Biochemical Reactions in Neurospora

Abstract

Para-aminobenzoic acid has recently been recognized as a factor required for the growth of a number of micro6rganisms' and as a member of the vitamin B group.2 One of the number of x-ray induced mutants of Neurospora crassa, obtained as described elsewhere,' is characterized by the loss of ability to synthesize p-aminobenzoic acid. This "aminobenzoicless" mutant is differentiated from normal by a single gene, is unable to grow on unsupplemented synthetic medium, but its growth is indistinguishable from normal when p-aminobenzoic acid is supplied.The mutant culture was maintained on "complete" medium containing yeast extract, malt extract and sucrose. Conidia from this stock culture were used for inoculating test cultures. The test medium was the "synthetic" or "m nimal" medium previously described8 containing inorganic salts and nitrogen, sucrose and 4 gammas of biotin4 per 1000 ml. Agar used in this synthetic medium was freed of p-aminobenzoic acid by repeated washing with distilled water. Cultures were incubated at 25°C.Crosses were made of the p-aminobenzoicless mutant (sex A, the equivalent of + in Lindegren's terminology5) with the normal strain (sex a); ascospores were dissected in order from asci and grown on complete medium. These cultures were tested by transferring them to minimal medium and observing for growth. In all, 142 single spore cultures were grown and tested. Of these, 72 proved to be able to synthesize p-aminobenzoic acid and 70 were unable to accomplish this. Of 11 asci from each of which all eight ascospore cultures were obtained, all had four normal and four mutant-type spores, and in no case were more than four spores of a kind obtained from any one ascus. The results in the 17 asci in which segregations for both sex and aminobenzoicless could be deduced are summarized in table 1. It is evident from these results that the aminobenzoicless character is inherited as though it were differentiated from normal by a single gene. There is no evidence of linkage of aminobenzoicless and sex. The fact that in 10 out of 17 asci aminobenzoicless segregated from its normal allele in the second division indicates that the aminobenzoicless locus is an appreciable distance from the centromere.In addition to the original aminobenzoicless mutant (ascospore isolate 1633), which was used for all physiological investigations described except those otherwise noted, an apparently independent occurrence of this mutant was recorded (isolate 5359). A cross between 5359 and 1633-63-6 234 PROC. N. A. S.

Reconstruction and Validation of a Genome-Scale Metabolic Model for the Filamentous Fungus Neurospora crassa Using FARM

“…Like arg-14 (Figure 2C), pab-1 serves as input to a metabolic cycle, so pab-1 is not required by FBA. However, consistent with limed-FBA's prediction, the pab-1 gene was reported to be essential by Beadle and Tatum's original publication [9], [10].…”

“…For example, FBA predicted that pab-1 was not essential, because pab-1 serves as input to a metabolic cycle; however, limed-FBA predicted that pab-1 was essential. In fact, essentiality of pab-1 was shown by the original experiment of Beadle and Tatum on Neurospora crassa [9], [10].…”

“…Work on Neurospora has led to essential discoveries in circadian rhythms [3], epigenetics [4], genome defense [5], mitochondrial biology [6], post-transcriptional gene silencing [7] and DNA repair [8]. Most famously, work in the 1940's by Beadle and Tatum led to the Nobel Prize-winning ‘one-gene-one-enzyme’ hypothesis that established the fundamental link between genes and proteins in all organisms [9], [10]. Work on Neurospora thus paved the way for modern genetics and molecular biology.…”

Metabolomics: the apogee of the omics trilogy

“…This hypothesis was based on their experimental results showing that X-ray-induced mutant strains of the fungus Neurospora crassa were unable to carry out specific biochemical reactions 35, 36 . By systematically adding individual compounds to minimal N. crassa media and screening for those that rescued the growth of mutant strains, Beadle and Tatum identified metabolites whose biosynthesis had been affected by genetic mutation.…”

Multitasking Bacterial Moonlighting Proteins in Bacterial Virulence and Infectious Disease

“…The ground-breaking work of Garrod [1] and Tatum and Beadle [2], which was carried out some time before the identification of the structure of DNA, led to the general expectation that every gene encodes a single protein, and that each protein serves a single function. However, in recent years, this logical view of biology has turned out to be overly simplistic.…”