title: [Formation of prototrophic colonies during crossing of deficient mutants of Aspergillus niger].
abstract: Deficient mutants of Aspergillus niger were obtained under the action of high doses of mutagens, viz. nitrosomethylurea, ethyleneimine, UV and gamma-rays, and their combinations. If the mutants to be crossed were derived from one and the same strain, prototrophous colonies of heterokaryons grew on a minimal medium, the frequency of their formation being 2-10(-7)-5-10(-7). If the mutants were obtained from different strains, heterokaryons appeared only in 40 per cent of crossings. Heterokaryons derived from mutants characterized by a low activity produced more acids. Heterokaryons obtained by crossing mutants with a high and a low activity had a higher productivity than a parent with a low activity, but a lower productivity than a parent with a high activity.
mesh_terms: D001230:Aspergillus / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D002467:Cell Nucleus; D002951:Citrates / Q000096:biosynthesis; D003433:Crosses, Genetic; D006579:Heterozygote; D009154:Mutation
chemical_list: D002951:Citrates
vernacular_title: Obrazovanie prototrofnykh koloniĭ pri skreshchivanii defitsitnykh mutantov Aspergillus niger.