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M Lieb

Publications and source records attributed to M Lieb.

34 records · Page 2Linked to original sources
PubMed1976

Heat-sensitive DNA-binding activity of the cI product of bacteriophage lambda.

The binding of lambda gene cI product to lambda DNA was studied at temperatures from 0 degrees C to 46 degrees C. Binding activity of the products of cIts mutants was higher at 22 degrees C than at 0 degrees C, 26 degrees C or 30 degrees C. Both cI+ and cIts products lost DNA-binding activity at 46 degrees C, but after subsequent cooling to 22 degrees C, they regained 50-100% of their activity.

Cold Temperature↗
PubMed1970

Wasting waste.

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Ecology↗
PubMed1970

Heat-sensitive early function in induced lambda Nsus lysogens.

Mutations in gene N of lambda prevent killing of the host bacterium after infection. However, derepression of Nsus prophages in nonpermissive (pm(-)) bacteria results in death of the lysogens. When prophages in pm(-)(lambdaCItsA-Nsus) lysogens are derepressed by raising the temperature to 45 C, the cells remain viable as long as they are at 45 C. However, they cannot form colonies at 33 C unless they have been superinfected, at the high temperature, by lambdaCI(+)-Nsus phage which produces repressor at 45 C. A large fraction of these "rescued," heat-inducible lysogens are lysogenized by the superinfecting phage, but lysogenization is not required for rescue. In pm(-)(lambdaCItsA-Nsus) lysogens growing at 45 C, the rate of deoxyribonucleic acid (DNA) synthesis shows a characteristic increase after the temperature is lowered. This increased DNA synthesis, which is correlated with loss of rescue potential, does not occur as long as the cultures are maintained at 45 C.

Coliphages↗
PubMed1970

Lambda mutants which persist as plasmids.

Lambda phages mutated in gene N do not kill sensitive host bacteria, but persist as plasmids. Plasmids are formed by genomes containing cI(+), and also by sus, ts, or c mutants of cI. Bacteria infected with two or more phage particles give rise to clones in which most of the bacteria are carriers. The introduced lambda genomes replicate more than once per bacterial division until there are 10 to 20 lambda plasmids per host genome. In bacteria containing both F and lambda plasmids, both replicate independently, and elimination by growth in acridine orange is also independent. Carriers of lambda Nsus plasmids are not immune, and there is complementation between the plasmids and superinfecting lambda mutants.

Acridines↗