Topic
Lambda phage
About: Lambda phage is a research topic. Over the lifetime, 1609 publications have been published within this topic receiving 84675 citations. The topic is also known as: Enterobacteria phage lambda.
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TL;DR: The complete genome of an oncogenic primate retrovirus, the San Francisco isolate of gibbon ape leukemia virus, is cloned in a lambda phage vector and the strong stop region of this DNA showed surprisingly low sequence homology to that of another gibbon apes leukemia virus isolate from an animal with similar disease.
Abstract: We have cloned the complete genome of an oncogenic primate retrovirus, the San Francisco isolate of gibbon ape leukemia virus, in a lambda phage vector. DNA sequence analysis and restriction endonuclease mapping of the inserted linear provirus demonstrated 9-base pair inverted repeats at its ends, flanking direct terminal repeats 470 base pairs in length. The (-) strong stop region of this DNA showed surprisingly low sequence homology to that of another gibbon ape leukemia virus isolate from an animal with similar disease. Analysis of the clone also revealed the terminal phosphate configuration of the linear provirus. The recombinant phage is suitable for direct use as a hybridization probe to detect homologous retroviral sequences in human cell lines.
21 citations
TL;DR: A model for the generation of various types of specialized transducing particles is presented that suggests generation of substantial numbers of specializedTransducing genomes which are heterogeneous but only some of which have terminally redundant ends.
Abstract: The temperate bacteriophage P22 mediates both generalized and specialized transduction in Salmonella typhimurium. Specialized transduction by phage P22 is different from, and less restricted than, the well characterized specialized transduction by phage lambda, due to differences in the phage DNA packaging mechanisms. Based on the properties of the DNA packaging mechanism of phage P22 a model for the generation of various types of specialized transducing particles is presented that suggests generation of substantial numbers of specialized transducing genomes which are heterogeneous but only some of which have terminally redundant ends. The primary attachment site, ataA, for phage P22 in S. typhimurium is located between the genes proA,B and supQ newD. (The newD gene is a substitute gene for the leuD gene, restoring leucine prototrophy of leuD mutant strains.) The proA,B and supQ newD genes are very closely linked and thus cotransducible by generalized transducing particles. Specialized transducing particles can carry either proA,B or supQ newD but not both simultaneously, and thus cannot give rise to cotransduction of the proA,B and supQ newD genes. This difference is used to calculate the frequency of generalized and specialized transducing particles from the observed cotransduction frequency in phage lysates. By this method, very high frequencies of supQ newD (10(-2)/PFU)- and proA,B (10(-3)/PFU)-specialized transducing particles were detected in lysates produced by induction of lysogenic strains. These transducing particles most of which would have been produced by independent aberrant excision events (which include in situ packaging), were of various types.
21 citations
TL;DR: The lysozyme of bacteriophage phiIN93 was purified to apparent homogeneity with Carboxymethyl Sepharose and Hydroxyapatie columns from lysates of the phage grown on Thermus aquaticus TZ2 and was found to be a novel type of thermophilic lyso enzyme, and exhibited conspicuous thermal stability at 95 degrees C for 1h in the presence of beta-mercaptoethanol.
21 citations
TL;DR: It is shown that a reduction in the level of intracellular supercoiled DNA occurs as the result of the presence of a 530 bp palindrome in bacteriophage lambda, suggesting that a feature of active monomeric DNA (probably its replication) is involved in inviability.
Abstract: Interest in the fate of long palindromic DNA sequences in E. coli has been kindled by the observation that their inviability is overcome in recBC sbcB strains and that these hosts permit the construction of DNA libraries containing long palindromic sequences present in the human genome. In this paper we show that a reduction in the level of intracellular supercoiled DNA occurs as the result of the presence of a 530 bp palindrome in bacteriophage lambda. This reduction occurs in Rec+ and recA strains but not in strains lacking exonucleases V and I (recBC sbcB). However, the DNA must be active (not repressed) for this reduction to be observed, since it is not seen in a Rec+ host lysogenic for phage lambda. These results argue against two hypotheses: firstly, that the palindrome causes inviability solely by interfering with packaging, and secondly, that it dose so solely by interfering with recombination. Conversely, these results suggest that a feature of active monomeric DNA (probably its replication) is involved in inviability.
21 citations
TL;DR: It is demonstrated that two factors are essential for the packaging of DNAs within λ phage particles; the presence of cosλ on the DNA molecule and an appropriate size of DNA.
Abstract: The mechanism of λ phage-mediated transduction of hybrid colicin E1 DNAs of various lengths was studied, and factors influencing the formation of these transducing particles were investigated. The results were as follows:
21 citations