The fungus Neurospora crassa. (a) Orange colonies of Neurospora growing on sugarcane. In nature, Neurospora colonies are most often found after fire, which activates dormant ascospores. (Fields of sugarcane are burned to remove foliage before harvesting the cane stalks.) (b) Developing Neurospora octads from a cross of wild type to a strain carrying an engineered allele of jellyfish green fluorescent protein fused to histone. The octads show the expected 4:4 Mendelian segregation of fluorescence. In some spores, the nucleus has divided mitotically to form two; eventually, each spore will contain several nuclei.
[(a) David J. Jacobson, Ph.D.; (b) Namboori B. Raju, Stanford University.]