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A physiological basis for some supressor mutations and possibly for one gene heterosis

Emerson, Sterling (1948) A physiological basis for some supressor mutations and possibly for one gene heterosis. Proceedings of the National Academy of Sciences of the United States of America, 34 (2). pp. 72-74. ISSN 0027-8424.

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A mutant strain of Neurospora which requires sulfonamides for growth at 35° frequently becomes altered so that it can grow at that temperature without sulfonamides.(1) In each instance analyzed, the developed ability to grow without sulfonamides has resulted from mutation of genes distinct from that responsible for the sulfonamide requirement. Each "reverted" strain has proved to be a heterocaryon, composed of two kinds of nuclei, both of which carry the gene (sfo) for sulfonamide requirement, but one also carries a new "supressor" gene. At least two independent supressor genes have been involved in such reversions. Homocaryotic strains have been isolated, some carrying both sfo and the supressor, others carrying the supressor alone. None of these isolates has the growth characteristics of wild type, but each shows some peculiar relationship to the p-aminobenzoic acid requirement, the nature of which is still obscure. In a few instances, artifically constructed heterocaryons between the sulfonamide-requiring strain and a strain carrying both the sulfonamide-requiring gene and a supressor have resulted in better growth on minimal medium than either strain is capable of by itself, thus reconstituting the situation observed in the original "reverted" heterocaryons.

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Additional Information:© 1948 by the National Academy of Sciences. Communicated by G.W. Beadle, December 13, 1947. Representing work supported in part by a grant from the Rockefeller Foundation, and in part by a grant from the American Cancer Society upon the recommendation of the Committee on Growth of the National Research Council.
Issue or Number:2
Record Number:CaltechAUTHORS:EMEpnas48
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9760
Deposited By: Tony Diaz
Deposited On:14 Mar 2008
Last Modified:03 Oct 2019 00:03

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