ROLE OF DNA SEQUENCES IN GENETIC RECOMBINATION IN THE ISO-1-CYTOCHROME <i>c</i> GENE OF YEAST. I. DISCREPANCIES BETWEEN PHYSICAL DISTANCES AND GENETIC DISTANCES DETERMINED BY FIVE MAPPING PROCEDURES

Moore, Carol W.; Sherman, Fred

doi:10.1093/genetics/79.3.397

Cited by 46 publications

(2 citation statements)

References 31 publications

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“…that the departures from additivity were kept at a minimum. Non-additivity in X-ray-induced mitotic recombination frequencies has also been noticed in several other systems (see for example, ESPOSITO 1968;PARKER and SHERMAN 1969;MOORE and SHERMAN 1975).…”

Section: X-ray Dose ( Kllorads )mentioning

confidence: 60%

“…Although there are many instances of departure from additivity in the X-ray map values, the total genetic length of the met15 gene has been estimated to be approximately 30 Xray map units (prototrophs per I O 8 survivors per rad). While distances between two mutational sites as measured by X-rayinduced rates of recombination cannot be reliably related to physical distances, the equivalence for many crosses with defined mutants was shown to be 23 to 52 amino acids per X-ray map unit (MOORE and SHERMAN 1975). Using these values, a rough estimate of the size of the monomeric product of the met15 gene would be from 65,000 to 170,-000 daltons.…”

Section: Discussionmentioning

confidence: 99%

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GENETIC AND PHYSIOLOGICAL CHARACTERIZATION OF met15 MUTANTS OF SACCHAROMYCES CEREVISIAE: A SELECTIVE SYSTEM FOR FORWARD AND REVERSE MUTATIONS

Singh

Sherman

1975

Genetics

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One hundred and thirty-three spontaneous and induced mutants of the met15 locus in Saccharomyces cerevisiae were characterized with respect to temperature sensitivity, osmotic remediability, interallelic complementation, and suppressibility by amber and ochre suppressors. Forty mutants are osmotic remedial; 17 of these, and no others, are also temperature-sensitive. Seven of 133 mutations are suppressible by an amber suppressor and 11 are suppressible by an ochre suppressor. Seventy percent of the mutants exhibited interallelic complementation, suggesting that the functional gene product of the met15 gene is a multimeric protein. Relative map positions of 30 met15 were estimated from the frequencies of X-ray-induced mitotic reversion of various heteroallelic diploids. All complementing nonsense mutations are located near one end of the gene in contrast to other nonsense mutations which span most of the gene, thus relating the direction of translation of the mRNA with respect to the fine-structure map. Recombination studies indicated that two of 30 mutants contained deletions of the entire met15 locus.-It was established that a variety of mutational types, including missense, nonsense, and deletions, are recovered with this unique system in which both forward and reverse mutations can be selected on the basis of methyl mercury resistance and methionine requirement of the met15 mutants.

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Section: X-ray Dose ( Kllorads )mentioning

confidence: 60%

Section: Discussionmentioning

confidence: 99%

GENETIC AND PHYSIOLOGICAL CHARACTERIZATION OF met15 MUTANTS OF SACCHAROMYCES CEREVISIAE: A SELECTIVE SYSTEM FOR FORWARD AND REVERSE MUTATIONS

Singh

Sherman

1975

Genetics

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Kinetics of loss of a recombinant plasmid in Bacillus subtilis

Shoham

Demain

1991

Biotech & Bioengineering

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Recombinant plasmid pCEDS is structurally unstable in Bacillus subtilis cultures. We have previously shown that stability can be independently increased by changing from a complex medium supporting high growth rates to a chemically-defined medium supporting a lower growth rate and removal of a 4.77-kb EcoRI fragment from pCED3 to give plasmid YS1. Further stabilization was achieved by combining the two approaches. In the present work, we show that the stabilization of the plasmid-encoded LacZ(+) phenotype can be explained solely by the effect on the growth rate ratio between cells containing modified and parental plasmids. By using modified stability experiments (where a single cell rather than a suspended colony was used to initiate growth), independent growth rate measurements, and a simple mathematical model, we can describe the kinetics of the loss of the LacZ(+) phenotype in terms of two variables, alpha and p (where alpha is the ratio of growth rates between modified and parental cells, and p is the probability of obtaining modified cells from parental cells). Under the conditions tested, the average values of alpha were 1.52 for cultures growing in complex medium, 1.28 for cultures growing in defined medium, and 1.18 for cultures containing the modified plasmid pYS1 growing in complex medium. The calculated p values ranged between 10(-8) and 10(-10) under all conditions. Plasmid (pYS137) was used to directly estimate plasmid deletion rates in B. subtilis and it showed a rate between 5 x 10(-8) and 1.1 x 10(-9) deletions/cell/generation. In contrast to B. subtilis, there were no detectable differences in growth rates between Escherichia coli strains harboring plasmid pCEDS and plasmid-free cells. These results explain the observed stability of pCEDS in E. coli cultures and indicate that readily detected instability in B. subtilis cultures can be the result of rare deletion events.

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