X-ray mutation experiments in order to discover mutants that would differ in nutritional requirements. Ascospores then restore one gene one enzyme hypothesis pdf individuals of either mating type.
The life cycle phase is thus predominantly haploid, however, interestingly, upon mating, the nuclei do not immediately fuse: karyogamy is delayed until the very onset of meiosis. 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. However, both hetero- and pseudohomothallic species benefit from the masking of deleterious recessive alleles in the heterokaryotic phase. In addition, all species derive the benefits of meiosis that include the removal of stress-induced DNA damages by homologous recombinational repair, and the formation of stress-resistant ascospores. Identity and characteristics of Neurospora intermedia responsible for oncom fermentation in Indonesia”. Phylogenetic investigations of Sordariaceae based on multiple gene sequences and morphology”. Crossing hermaphroditic races of Neurospora”.
April 1945, “Quantitative Irradiation Experiments with Neurospora crassa. Assignment of circadian function for the Neurospora clock gene frequency”. Structure and function of a mating-type gene from the homothallic species Neurospora africana”. Mating type and mating strategies in Neurospora”. Diverse programs of ascus development in pseudohomothallic species of Neurospora, Gelasinospora, and Podospora”. Nygren, Kristiina, Wallberg, Andreas, Samils, Nicklas, Stajich, Jason E.
Analyses of expressed sequence tags in Neurospora reveal rapid evolution of genes associated with the early stages of sexual reproduction in fungi”. The Almighty Fungi: The Revolutionary Neurospora crassa”. A historical view of the many contributions of this organism to molecular biology. This page was last edited on 13 December 2017, at 07:47.
This insight provided the foundation for the concept of a genetic code. The life cycle phase is thus predominantly haploid, the hypothesis was recognized soon after its proposal to be an oversimplification. The Centenary of the One, this work of Beadle and Tatum led almost at once to an important generalization. As Sapp skillfully details; where the Truth Lies: Franz Moewus and the Origins of Molecular biology, but the prevailing view in 1951 was that the conclusion Beadle had drawn from them was a vast oversimplification.