T1 bacteriophage production in Escherichia coli

Feiner, Rose R. (Columbia University, New York, N.Y.) and Solon A. Ellison. T1 bacteriophage production in Escherichia coli. J. Bacteriol. 85:7-11. 1963.-Progeny released from complexes formed between unirradiated Escherichia coli strain Bs-1 and ultraviolet (UV)-irradiated phage T1 were equally infective for strains B and Bs-1, and were therefore not hostmodified. The capacity of Bs-1 for unirradiated or irradiated T1 is relatively insensitive to UV irradiation, as compared with that of strains B and B/r. In all three strains of E. coli, B, B/r, and Bs-1, the UV sensitivity of the capacity for phage T1 is independent of the UV sensitivity of colony-forming ability. These findings are discussed in relation to the partial genetic homology hypothesis.

Antibody formation initiated in vitro. II. Antibody synthesis in x-irradiated recipients of diffusion chambers containing nucleic acid derived from macrophages incubated with antigen

The diffusion chamber technique permitted the demonstration of specific antibody formation in x-irradiated recipients of such chambers filled with normal lymph node cells and a cell-free homogenate of macrophages which had been incubated in intro with T2 bacteriophage. The activity of the cell-free homogenate was retained in its RNA fraction isolated by means of the phenol method. No antibody formation occurred if such RNA was treated with RNAase. On sucrose gradients (5 to 20 per cent), the active RNA was found to be present in the top third layer. The question of the possible presence of antigen complexed to the RNA is discussed.

Sequences of synthesis of gamma-1 macroglobulin and gamma-2 globulin antibodies during primary and secondary responses to proteins, salmonella antigens, and phage

The nature of the antibodies produced by the rabbit during the primary and secondary responses to T(2) phage, proteins, and the O and H antigens of Salmonella typhosa has been determined. Immune sera have been fractionated by zone electrophoresis, sucrose density ultracentrifugation, and anion exchange chromatography. The resulting fractions have been assayed by phage neutralization or hemagglutination (antisera to proteins) or bacterial agglutination. In confirmation and extension of earlier work from this laboratory, the primary response to these antigens, with the exception of the O antigen of the Salmonella, included the early synthesis of 19S, gamma-1 globulin antibody, and the later synthesis of 7S, gamma-2 globulin antibody. The primary response to the O antigen consisted of the synthesis of only a macroglobulin agglutinin. The secondary response to the proteins, including the H antigen of the Salmonella, comprised the early synthesis of large amounts of the 7S gamma-2 globulin antibody to the same level attained during the primary response. The secondary response to the phage consisted in the synthesis of 7S, gamma-2 globulin antibody alone. Treatment of the macroglobulin phage-neutralizing antibody with mercaptoethanol resulted in complete loss of its neutralizing activity. A working hypothesis to explain these observations was presented. A salient feature of this hypothesis was the suggestion that different cells synthesized the two distinct molecular forms of antibody. The significance of the sequential synthesis of the two forms of antibody is not known. It was proposed that the system for synthesis of macroglobulin antibody is an auxiliary system for antibody synthesis, perhaps the first to develop phylogenetically and ontogenetically. It is felt that the present observations indicate a clear-cut qualitative distinction between the primary and secondary responses to immunization whereby these responses might be identified in various experimental situations. It is also felt that these findings with the primary and secondary responses to various antigens in the rabbit may be of widespread occurrence in nature among a variety of species.

Antibody formation. IV. Formation of rapidly and slowly sedimenting antibodies and immunological memory to bacteriophage phi-X 174

Injection of a sufficient dose of bacteriophage phiX 174 into guinea pigs results in the formation of rapidly sedimenting antibody molecules (19S), and later, slowly sedimenting molecules (7S). Above a threshold dose of antigen, the relative rate of 19S formation is maximal and dose-independent; below this dose, slower relative rates are obtained. The time for doubling the serum 19S level is as short as 6 to 8 hours, suggesting that the absolute rate of antibody formation per cell is increasing in addition to proliferation of antibody-producing cells. Synthesis of 19S after injection of 10(10) phiX virtually ceases at 10 days after which 19S antibody activity disappears from the circulation with a half-life of approximately 24 hours. A second injection of phiX on day 5 or 9 prolongs 19S synthesis, indicating that antigen not only can regulate the relative rate, but also is essential for continued synthesis of 19S. 19S synthesis is also prolonged in guinea pigs by injection of phiX with endotoxin or by 400 r whole body x-irradiation 24 hours after injection of phage into rabbits. The primary 7S response is not detected until approximately 1 week after immunization and relative rates are antigen-dependent. Primary 7S synthesis can continue for many months and leads to preparation for a secondary antibody response (immunological memory) during which only 7S is detected. In contrast, in animals that form precipitating 19S without detectable 7S, a second injection of phage 1 month later results in a second 19S response which closely resembles the first. These findings have led to the suggestion that formation of 19S does not lead to persisting immunological memory.

Physicochemical studies on the reaction between formaldehyde and DNA

The reaction between formaldehyde and phage T7 DNA has been studied by optical absorbance and sedimentation measurements. Through the course of denaturation, OD(200) and s(20, w) rise; after the attainment of full hyperchromicity the s(20, w) falls sharply, suggesting a decrease in molecular weight. Conditions in which formaldehyde causes cross-linking are defined. Some experimental applications of the denaturation technique are given. Evidence which suggests that preformed single-strand interruptions may exist in phage DNA is briefly discussed.

The adsorption of bacteriophage phi-X174 to its host

The adsorption of purified varphiX174 to E. coli C and to E. coli C cell walls was investigated. Adsorption was measured by assaying for unadsorbed plaque formers. The amount of irreversible and reversible adsorption depends upon pH and divalent ion concentration. Maximum irreversible adsorption occurs in 0.1 M CaCl(2) at 36 degrees C. There is no detectable reversible adsorption at conditions of pH and CaCl(2) concentration optimum for irreversible adsorption. Under these optimum conditions, diffusion is not the rate-limiting factor, and the encounter efficiency appears to be low. The rate constant is 1.0 x 10(-10) ml/sec. Phages adsorbed irreversibly to live cells cause infection and to the isolated cell walls apparently cause release of DNA. There is a specific varphiX174 receptor site on the mucocomplex portion of the cell wall.

Temperature and the reproduction of lambda-phage mutants

Groman, Neal B. (University of Washington, Seattle). Temperature and the reproduction of two lambda-phage mutants. J. Bacteriol. 84:438-445. 1962.-A comparative study of phage lambda, and mutants lambdatem and lambda11(2), was made, with particular emphasis on the effect of elevated temperature (44 C) on phage reproduction. Phage lambdatem was selected at 44 C and lambda11(2) was isolated from the late-lysing fraction of bacteria at 37 C. All three phages are similar in their host range, immunity pattern, and in the rate of inactivation of free phage by anti-lambda antibody and heat. Differences were observed in their plaque size and in their relative plating efficiency at 37 and 44 C. One-step growth curve studies showed that phages lambda and lambdatem are similar in the time intracellular phage appears and in their rate of maturation at 37 C. These time and rate parameters were unchanged at 44 C. Both lambda and lambdatem exhibited a reduced latent period at 44 C. However, the latent period of lambdatem was longer than that of lambda at both 37 and 44 C, and its relative 44 C/37 C yield was about 40% while that of lambda is about 3%. Phage lambdatem may be characterized as a lambda mutant with an altered latent period. Phage lambda11(2) was similar to lambda and lambdatem at 37 C, but at 44 C behaved quite differently. The time of appearance of intracellular phage was delayed, compared to 37 C, and the rate of maturation was slower. Phage production at 44 C was about 16% that at 37 C. On further investigation, it was observed that induced Escherichia coli K-12 (lambda11(2)) failed to lyse at 44 C, although it did lyse at 37 C. Lysis inhibition was imposed almost immediately by transferring cells from 37 C to 44 C at any time during the reproductive cycle, including the lytic phase. The behavior of lambda11(2) at 44 C disposed of the possibility that the lytic step was the only step in the phage cycle sensitive to variations in temperature. However, it appeared that the lytic step was a consistant target for its action.

Some observations on the role of coliphages in the number of Escherichia coli in oxidation ponds

No evidence was found to support the view that coliphages as such play an important role in reducing the number of E. coli in sewage water when it is treated in oxidation ponds. Coliphages seem to have greater powers of survival than E. coli in oxidation ponds.