Radiation biophysical study of biological molecules. Progress report, July 1, 1976--August 31, 1977. [X and uv radiation, lambda phage, Escherichia coli]

Abstract When one of two infecting lambda phage types in a replication-blocked cross is chi + and DNA packaging is divorced from the RecBCD-chi interaction, complementary chi-stimulated recombinants are recovered equally in mass lysates only if the chi + parent is in excess in the infecting parental mixture. Otherwise, the chi 0 recombinant is recovered in excess. This observation implies that, along with the chi 0 chromosome, two chi + parent chromosomes are involved in the formation of each chi + recombinant. The trimolecular nature of chi +-stimulated recombination is manifest in recombination between lambda and a plasmid. When lambda recombines with a plasmid via the RecBCD pathway, the resulting chromosome has an enhanced probability of undergoing lambda x lambda recombination in the interval into which the plasmid was incorporated. These two observations support a model in which DNA is degraded by Exo V from cos, the sequence that determines the end of packaged lambda DNA and acts as point of entry for RecBCD enzyme, to chi, the DNA sequence that stimulates the RecBCD enzyme to effect recombination. The model supposes that chi acts by ejecting the RecD subunit from the RecBCD enzyme with two consequences. (1) ExoV activity is blocked leaving a highly recombinagenic, frayed duplex end near chi, and (2) as the enzyme stripped of the RecD subunit travels beyond chi it is competent to catalyze reciprocal recombination.

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COMPLEMENTARITY BETWEEN LAMBDA ( ) PHAGE AND ESCHERICHIA COLI

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.50.6.1177 ◽

1963 ◽

Vol 50 (6) ◽

pp. 1177-1184 ◽

Cited By ~ 16

Author(s):

M. H. Green

Keyword(s):

Escherichia Coli ◽

Lambda Phage

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Escherichia coli host strains SURETM and SRB fail to preserve a palindrome cloned in lambda phage: improved alternate host strains

Gene ◽

10.1016/0378-1119(93)90758-u ◽

1993 ◽

Vol 124 (1) ◽

pp. 29-35 ◽

Cited By ~ 15

Author(s):

J.P. Doherty ◽

R. Lindeman ◽

R.J. Trent ◽

M.W. Graham ◽

D.M. Woodcock

Keyword(s):

Escherichia Coli ◽

Lambda Phage ◽

Alternate Host ◽

Host Strains

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Dry Bio-Decontamination Process in Reduced-Pressure O2 Plasma

Applied Sciences ◽

10.3390/app9091933 ◽

2019 ◽

Vol 9 (9) ◽

pp. 1933 ◽

Cited By ~ 1

Author(s):

Hongxia Liu ◽

Xinxin Feng ◽

Xin Ma ◽

Jinzhuo Xie ◽

Chi He

Keyword(s):

Escherichia Coli ◽

Free Radicals ◽

Cell Membrane ◽

Uv Radiation ◽

Oxygen Plasma ◽

Bacterial Suspension ◽

Reduced Pressure ◽

Electrons And Ions ◽

Agarose Electrophoresis ◽

Electronic Microscope

The main objective of this work was to fully understand the bio-decontamination process in a reduced-pressure oxygen plasma. Gram-negative Escherichia coli species was chosen as the target microorganism in this test. The comparison of decontamination efficacy between plasma total and UV radiation individually under various treatment parameters and tests of DNA agarose electrophoresis were made to evaluate the inactivation effect of UV radiation. The quantity of protein leakage and the concentration of malondialdehyde (MDA), which are markers of the end products of lipid peroxidation, in bacterial suspension after treatment were determined to estimate the contribution of both charged particles and free radicals for bacterial death. In addition, a scanning electronic microscope was used to visualize the plasma effect on microorganisms. The results showed that the essential action of the oxygen plasma on Escherichia coli is believed to be attributed to the fast and intense etching on cell membrane by electrons and ions. Attacks on polyunsaturation fatty acid (PUFA) in the cell membrane by oxygen free radicals and the destruction of the DNA in the cell by UV radiation are accessorial during an effective decontamination process.

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