https://www.cell.com/cell/pdf/0092-8674(87)90503-4.pdf

The physical map of the whole E. coli chromosome: application of a new strategy for rapid analysis and sorting of a large genomic library.

Most of us doing research have a preferred material, a set of well-tried techniques, a standing list of unsolved problems, ways of looking at or of doing things, which we share to a large extent with colleagues in the same laboratory and others in the same area of specialization, be they friends, former associates, or competitors. All this and more is encompassed by the concept of "experimental system" as introduced and used by Hans-Jorg Rheinberger (76, 77), a historian of science. His concept, rather flexible and rich in metaphors, may be easily adapted to the present narrative, which proceeds from a personal view rather than from a critical historical examination. A careful restriction of material, techniques, and nomenclature allows more constructive interactions between different laboratories and different generations of scientists in the same field. Of course, carried out to excess, this process will stifle developments in new areas and defer some discoveries. Max Delbruck, who in the early forties had forcefully advocated the study of bacteriophage as the royal road to the secrets of replication and recombination, was quite outspoken about the necessity for workers on that road to use a common material (the T phages in Escherichia coli B) and precisely standardized techniques (1). Of course, the T phages are generally virulent, take-no-prisoner parasites of bacteria and thus could not instruct us about the more shadowy interactions between "weaker" bacteriophages and their bacterial hosts: about lysogeny, where infection meets heredity.

Lysogeny at mid-twentieth century: P1, P2, and other experimental systems.

A comprehensive molecular map of bacteriophage lambda.

We have isolated a strain of Escherichia coli K-12 carrying a mutation, polA12, that results in the synthesis of a temperature-sensitive deoxyribonucleic acid (DNA) polymerase I. The double mutants polA12 recA56 and polA12 recB21, constructed at 30 C, are inviable at 42 C. About 90% of the cells of both double mutants die after 2 hr of incubation at 42 C. Both double mutants filament at 42 C and show a dependence on high cell density for growth at 30 C. In polA12 recB21 cells at 42 C, DNA and protein synthesis gradually stop in parallel. In polA12 recA56 cells, DNA synthesis continues for at least 1 hr at 42 C, and there is extensive DNA degradation. The results suggest that the primary lesion in these double mutants is not in DNA replication per se.

Conditional Lethality of recA and recB Derivatives of a Strain of Escherichia coli K-12 with a Temperature-Sensitive Deoxyribonucleic Acid Polymerase I

Replication of bacteriophage λ DNA dependent on the function of host and viral genes: I. Interaction of red, gam and rec

The efficiency of plating of wild-type λ on a host lysogenic for P2 is less than 10-6, and only a small number of infected cells produce progeny phage. Lambda can adsorb and inject its DNA normally in such cells; the DNA can circularize and is not nicked or degraded, but replication is severely impaired. Mutants of P2, which as prophages no longer interfere with λ, have been isolated and found to be recessive to wild type, implying that P2 prophage codes for a diffusible product involved in λ interference. The P2 gene product responsible for preventing λ growth also kills recombination-deficient bacteria of the recB and recC classes under conditions where P2 does not normally kill the host. Mutants of λ that are resistant to interference are recessive to wild-type λ. Thus λ actively participates in its own interference. The λ-mutants that are resistant to interference are unable to synthesize at least two nonessential proteins. In addition, they are unable to grow on recombination-deficient bacteria of the recA class, but they can grow on recA recB double mutants.

https://www.pnas.org/content/pnas/66/3/587.full.pdf

Harvey Bialy

Papers

Bacteriophage lambda; abortive infection of bacteria lysogenic for phage P2.

Bacteriophage P2: Interaction with phage lambda and with recombination-deficient bacteria