George Wells Beadle and Edward Lawrie Tatum in X-ray mutation experiments in order to discover mutants that would differ in nutritional requirements. The results of their experiments led them to the one gene-one enzyme hypothesis, in which they postulated that every enzyme was encoded with its own gene. Research with Neurospora is reported semi-annually at the Neurospora Meeting at Asilomar, California, coordinated by the Fungal Genetics Stock Center. Mutant and wild-type strains of Neurospora are available from the FGSC. The FGSC also publishes the Fungal Genetics Reports. Important people in Neurospora research: Bernard Ogilvie Dodge (1872–1960) George Beadle (Nobel Prize in Physiology or Medicine, 1958) Edward Tatum (Nobel Prize in Physiology or Medicine, 1958) Esther Lederberg<ref>Hollaender, A., Sansome E. R., Zimmer, E., Demerec, M., April 1945, "Quantitative Irradiation Experiments with Neurospora crassa. II. Ultraviolet Irradiation", American Journal of Botany 32(4):226-235 Also: "Quantitative effects of radiation on mutation production in Neurospora crassa", Records of the Genetics Society of America, Number Thirteen, 1944</ref> Norman Giles David Perkins Robert Metzenberg Norman Horowitz Herschel K. Mitchell Mary B. Mitchell Martha Merrow Sexual reproduction In the heterothallic species Neurospora crassa, interaction of haploid strains of opposite mating type is necessary for the occurrence of sexual reproduction and the production of ascospores by meiosis. Ascospores then restore haploid individuals of either mating type. The life cycle phase is thus predominantly haploid, however, upon mating, the nuclei do not immediately fuse: karyogamy is delayed until the very onset of meiosis. The resulting mycelium is called a heterokaryon, and is neither diploid, nor haploid. The genus Neurospora also includes homothallic species in which a single haploid individual carries both mating type loci and can undergo self-fertilization leading to meiosis and sexual reproduction. Neurospora africana is an example of such a species. Additionally, some "Neurospora" species are said pseudohomothallic. They carry both mating types, but in separate nuclei in the same individual. Two haploid nuclei originating from the same meiosis are packaged into one ascospore. The individual is thus permanently heterokaryotic. Examples of this mating system include "Neurospora tetrasperma" and "Neurospora tetraspora". Because heterothallic species necessarily undergo some degree of outcrossing they may benefit from a higher efficiency of selection because of higher effective recombination rates. In contrast, pseudohomothallic and homothallic species do not outcross (or rarely) and do not experience these benefits: in homothallics a reduced efficiency of negative selection has been shown. However, both hetero- and pseudohomothallic