GENETIC INTERACTION AMONG STREPTOMYCETES: HETEROKARYOSIS AND SYNKARYOSIS

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Abstract
[long dash]Heterokaryosis in streptomycetes denotes a condition in which genetically unlike nuclei are perpetuated within a common cytoplasm as the result of hyphal anastomosis. Conidia formed by heterokaryons are of parental type only. Heterokaryosis, as defined, was demonstrated between mutants of the same strain of Streptomyces griseus, S. griseoflavus, S. fradiae, S. venezuelae, S. albus, S. sphaeroldes, and S. coelicolor, but not between mutants of diverse origin. Heterokaryons between amino acid-requiring mutants of S. caelicolor, and occasionally of other species, were "nutritionally unbalanced," i.e., did not grow on minimal media unless at least a portion of the parental requirements was supplied. Synkaryosis is the fusion of unlike nuclei within heterokaryons and subsequent reassortment of genetic characters to yield conidia of recombinant types. Two species, S. coelicolor and S. fradiae, exhibited synkaryosis. The quantitative results were strongly biased by selecUve forces active between karyogamy and the scoring of recombinant colonies.
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