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Episomic suppression of phenotype in Salmonella

Published online by Cambridge University Press:  14 April 2009

P. F. Smith-Keary  and
G. W. P. Dawson
P. F. Smith-Keary
Affiliation:
Department of Genetics, Trinity College, Dublin
G. W. P. Dawson
Affiliation:
Department of Genetics, Trinity College, Dublin
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1. An auxotroph of Salmonella typhimurium, pro-401, was isolated in a strain that was unstable at the su-leuA locus. The auxotrophy of pro-401 is probably due to the attachment of a controlling episome to the proline region of the genome where it suppresses gene expression.

2. The controlling episome frequently transposes over short distances so that all clones consist of cells, mixed for the site at which the controlling episome is attached; homologous transductions yield prototrophs.

3. The controlling episome can transpose to a different complementation group; homologous transductions yield abortive transductants; syntrophism occurs between cells that are ‘mutant’ in different complementation groups to give reversions consisting entirely of auxotrophic cells which are called auxotrophic reversions.

4. The controlling episome transposes over very short distances and never to beyond the limits of this proline region of the genome; no wild-type reversions were found.

5. The controlling episome can be located at relatively distant proline sites in different clones; prototrophs from transductions between clones that are separated by many subculturings can be 100 times more frequent than from homologous transductions.

6. The controlling episome has its frequency of transposition to different complementation groups increased by UV; irradiation increases the frequency of auxotrophic reversions.

7. The controlling episome continues to transpose in stored cells.

8. The pattern of reversions of pro-401 is different in these studies from its pattern two years previously. This is discussed.

Type
Research Article
Information
Genetics Research , Volume 5 , Issue 2 , July 1964 , pp. 269 - 281
Copyright
Copyright © Cambridge University Press 1964

References

REFERENCES

Dawson, G. W. P. & Smith-Keary, P. F. (1960). Analysis of the su-leuA locus in Salmonella typhimurium. Heredity, 15, 339–350.CrossRefGoogle Scholar
Dawson, G. W. P. & Smith-Keary, P. F. (1963). Episomic control of mutation in Salmonella typhimurium. Heredity, 18, 1–20.CrossRefGoogle ScholarPubMed
Demerec, M. (1963). Selfer mutants of Salmonella typhimurium. Genetics, 48, 1519–1531.CrossRefGoogle ScholarPubMed
McClintock, B. (1956). Controlling elements and the gene. Cold Spr. Harb. Symp. quant. Biol. 21, 197–216.CrossRefGoogle ScholarPubMed
McClintock, B. (1958). The suppressor-mutator system of control of gene action in maize. Carnegie Inst. Wash. Year Book, 57, 415–419.Google Scholar
Miyake, T. (1960). Mutator factor in Salmonella typhimurium. Nature, Lond., 183, 1586.CrossRefGoogle Scholar
Smith-Keary, P. F. (1960). A suppressor of leucineless in Salmonella typhimurium. Heredity, 14, 61–71.CrossRefGoogle Scholar
Treffers, H. P., Spinelli, V. & Belser, N. D. (1954). A factor (or mutator gene) influencing mutation rate in Escherichia coli. Proc. nat. Acad. Sci., Wash., 40, 1064–1071.CrossRefGoogle Scholar