Recombinations of Mutant Phages of Bacillus Megatherium 899a

Murphy, James S.

doi:10.1084/jem.98.6.657

Cited by 15 publications

(5 citation statements)

References 7 publications

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“…Both types bred true. A similar phenomenon was reported in the A phages of S. typhi-murium (Boyd, 1951), in B. megatherium (Murphy, 1953), and in E. coli K12 (Jacob, Wollman & Siminovitch, 1953); there is little doubt that the production of such virulent mutants is a property common to all temperate phages, though in the types which produce small plaques these mutants are difficult to detect and isolate, and so far few have been reported from this source. The ratio of virulent to temperate particles in a lysate is variable but low-in the order of I to 5000 or even below this figure.…”

Section: (I) Morphologysupporting

confidence: 64%

Bacteriophage

Boyd

1956

Biological Reviews

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SUMMARY In the lysogenic bacterium the bacterial virus exists as prophage. It is composed of desoxyribosenucleic acid (DNA) and occupies a defined site on the bacterial chromosome. Normally the prophage divides in harmony with the nucleus of the bacterium, so that lysogenesis is hereditary. Occasionally the prophage reverts from symbiosis to virulence, and multiplies at the expense of its host, producing a brood of free phage particles. This is believed to occur when the prophage becomes detached from the chromosome. Free phage particles may be temperate (capable of reproducing lysogenesis in a sensitive bacterium) or virulent (unable to produce lysogenesis and multiplying only at the expense of the doomed host). Temperate particles greatly outnumber virulent particles, which are in fact mutants. Reasons are given for believing that all virulent phages (such as the T series of coliphages) originate in this way. Free phage particles have a characteristic tadpole‐like structure of varying proportions. The tail and the covering of the head are composed of protein, which has specific antigenic characters. The contents of the head consist of DNA. The protein envelope and tail of the particle are chiefly mechanical in function. The tail adheres to the host bacterium and breaches its covering membrane. The contents of the head are then injected into the bacterium. They constitute the infective element. A temperate phage may produce lysogenesis or may multiply in the same way as a virulent particle. Various factors facilitate or interfere with the establishment of lysogenesis. There is evidence to suggest that some temperate particles are specially endowed to produce lysogenesis, while others can undergo only productive development at the expense of the host. Virulent particles multiply only by productive development. The infecting virus displaces the genetic apparatus of the bacterium and directs the bacterial enzymes to its own ends. The nucleic acid of the bacterium, augmented if necessary by newly synthesized material from the culture medium, is broken down to nucleotide level or lower, and resynthesized into viral DNA. Protein is synthesized separately. Ultimately both are assembled into mature particles. Lysogenic bacteria are immune to the phage they produce, and to allied types. Occasional virulent mutants are exceptions to this rule. In certain cases temperate phage particles transduce genetic characters from one bacterium to another. Bacterial species (the classical example being Salmonella typhi) can be broken down into numerous ‘phage‐types’ by tests which exploit the hereditary immunity conferred by the various symbiotic phages. Alternatively, different races of a bacterial species can be recognized by isolating and identifying the symbiotic phage which they carry.

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Section: (I) Morphologysupporting

confidence: 64%

Bacteriophage

Boyd

1956

Biological Reviews

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“…Table III gives a description of the various mutants found and illustrates them. Mutants already described have been starred (3,4). It will be seen that no radically different types have been found except u which is very turbid.…”

Section: O A~papaginementioning

confidence: 75%

“…However, the task of completely differentiating these phages is beyond the scope of this project. In spite of these diflicul- (3,4) and are included here merely for comparative purposes. N •ffi normal size.…”

Section: O A~papaginementioning

confidence: 99%

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Some Mutant Phages Produced Directly by Bacillus Megatherium 899a With Their Rate of Occurrence

Murphy

1954

Journal of Experimental Medicine

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The purpose of this study is to find out if bacteriophage mutants are produced directly by the lysogenic bacterial strain Bacillus megatherium 899a (1) and, if so, what types and frequencies are to be found. The results indicate that in all probability phage mutants are produced directly from lysogenic B. megatkeriura 899a and occur with a frequency of about one recognizable plaque mutant per 2000 normal individuals.The experiment was designed to show whether passage through a sensitive cell was a major factor in the apparent production of mutants. The possibility of passage through a sensitive cell in the lysogenic culture was controlled by contrasting B. megatherium 899a growing in two media, one in which infection was virtually certain (peptone) and one in which it was highly unlikely (asparagine) (2). If the number of mutants was approximately the same in the two cultures, it would show that the infection of a sensitive cell occurring in the lysogenic culture did not play an important role in the production of mutants. If there was a significant variation in the two cultures and it could be demonstrated that the two mutation rates were not correlated, the plating suspension could be ruled out in the occurrence of mutants.The results indicate that sensitive cells in the lysogenic culture do not play a significant role. The plating suspension test did not reveal as clear cut a result but gives every reason to believe that mutants are produced directly by B. megatherium 899a (lysogenic).An attempt has been made to isolate and classify all the mutant phages recognized during this study and data are included which give some indication of the frequency of occurrence of these mutants. Several new mutants have been found, increasing the number described to 19 (3, 4). Materials and MethodsBacterial strains.--B, megatherium 899a (lysogenic) isolated by den Dooren de Jong (1) was sent to this laboratory by" Gratia in 1949. It has been transferred weekly on 2 per cent 657

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“…Recombination between plaque type mutants of temperate phages has been described by Murphy (1953), Kaiser (1955), and Jacob and Wollman (1955); such a phenomenon between host range mutants has not been reported except for that of a doubly lysogenic strain with two X mutants (Whitfield and Appleyard, 1958). Groman et al (1958) reported recombination of two temperate phages of C. diphtheriae in the doubly lysogenic cell established by superinfection of a lysogenic strain with a temperate phage.…”

Section: Discussionmentioning

confidence: 99%

DEVELOPMENT OF HOST RANGE MUTANTS THROUGH THE INTER-ACTION OF TWO CLOSELY RELATED TEMPERATE PHAGES IN CORYNEBACTERIUM DIPHTHERIAE

Hatano

Kurokawa

1960

J Bacteriol

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Development of host range mutants of bacteriophage has been believed generally to be a result of the spontaneous mutation of original phage (Luria, 1945). Recently, however, it has been proposed (Hershey et al., 1954) that the host range mutants of T3 phage arose from interactions between phage and bacterial cell, possibly in the nature of genetic substitutions. Fukumi and Nojima (1957) proposed a unitary theory which explained the host range mutation and the host-controlled variation (Luria and Human, 1952; and Bertani and Weigle, 1953) on the basis of the cross-over between host and phage genes (Weigle and Dulbecco, 1953;

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Recombinations of Mutant Phages of Bacillus Megatherium 899a

Cited by 15 publications

References 7 publications

Bacteriophage

Bacteriophage

Some Mutant Phages Produced Directly by Bacillus Megatherium 899a With Their Rate of Occurrence

DEVELOPMENT OF HOST RANGE MUTANTS THROUGH THE INTER-ACTION OF TWO CLOSELY RELATED TEMPERATE PHAGES IN CORYNEBACTERIUM DIPHTHERIAE

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