Search results for "Bacteriophage"

Clostridium difficile IStron CdISt1: Discovery of a Variant Encoding Two Complete Transposase-Like Proteins

2004

ABSTRACT Screening a Clostridium difficile strain collection for the chimeric element Cd ISt1 , we identified two additional variants, designated Cd ISt1 -0 and Cd ISt1 -III. In in vitro assays, we could prove the self-splicing ribozyme activity of these variants. Structural comparison of all known Cd ISt1 variants led us to define four types of IStrons that we designated Cd ISt1 -0 through Cd ISt1 -III. Since Cd ISt1 -0 encodes two complete transposase-like proteins (TlpA and TlpB), we suggest that it represents the original genetic element, hypothesized before to have originated by fusion of a group I intron and an insertion sequence element.

Application of DNA Polymorphisms in Paternity Testing in Germany: Solution of an Incest Case Using Bacteriophage M13 Hybridization with Hypervariable…

1988

More than 25 blood, serum, and enzyme polymorphisms have been introduced into paternity testing in Germany in recent years (Rittner, 1975). If a “no” decision is defined by exclusion, and a “yes” decision requires a probability of 99.73 % or more, more than 90 % of court cases can be solved in this respect. A few cases not being clarified by a standard expertise include: 1) Cases with more than one alleged man if the men and/or the mother and the men are related. 2) Some cases where the putative father is deceased, and neither the parents nor the legitimate offspring are available for the study. 3) Cases where possible exclusion in a given polymorphic system interferes with an overall evide…

Minisatellite DNA Probe MZ 1.3: Application in Paternity Testing and Estimate of the Number of Genetic Loci

1990

The use of hypervariable DNA minisatellite probes recognizing repetitive genomic DNA sequences has become a valuable and powerful tool in paternity testing as well as in forensic stain analysis (Jeffreys et al. 1985, 1987; Werrett et al. 1988). It has been shown that bacteriophage Ml3 DNA can also be used to obtain hypervariable DNA restriction fragment patterns in humans and other species (Vassart et al. 1987). To obtain more informative and specific fragment patterns for the DNA ‘fingerprint’ analysis in man, we have used Ml3 DNA as a probe to screen a human genomic library. Thus, we have isolated the minisatellite DNA probe MZ 1.3 (Schacker et al., in press). MZ 1.3 is a 1.9 kb fragment …

EFFECT OF DELETERIOUS MUTATION-ACCUMULATION ON THE FITNESS OF RNA BACTERIOPHAGE MS2

2000

RNA viruses show the highest mutation rate in nature. It has been extensively demonstrated that, in the absence of purifying selection, RNA viruses accumulate deleterious mutations at a high rate. However, the parameters describing this accumulation are, in general, poorly understood. The present study reports evidences for fitness declines by the accumulation of deleterious mutations in the bacteriophage MS2. We estimated the rate of fitness decline to be as high as 16% per bottleneck transfer. In addition, our results agree with an additive model of fitness effects.

Rapid evolution of translational control mechanisms in RNA genomes

1997

We have introduced 13 base substitutions into the coat protein gene of RNA bacteriophage MS2. The mutations, which are clustered ahead of the overlapping lysis cistron, do not change the amino acid sequence of the coat protein, but they disrupt a local hairpin, which is needed to control translation of the lysis gene. The mutations decreased the phage titer by four orders of magnitude but, upon passaging, the virus accumulated suppressor mutations that raised the fitness to almost wild-type level. Analysis of the pseudorevertants showed that the disruption of the local hairpin, controlling expression of the lysis gene, had apparently been so complete that its restoration by chance mutations…

Prisoner's dilemma in an RNA virus

1999

The evolution of competitive interactions among viruses1 was studied in the RNA phage φ6 at high and low multiplicities of infection (that is, at high and low ratios of infecting phage to host cells). At high multiplicities, many phage infect and reproduce in the same host cell, whereas at low multiplicities the viruses reproduce mainly as clones. An unexpected result of this study1 was that phage grown at high rates of co-infection increased in fitness initially, but then evolved lowered fitness. Here we show that the fitness of the high-multiplicity phage relative to their ancestors generates a pay-off matrix conforming to the prisoner's dilemma strategy of game theory2,3. In this strateg…

EXPERIMENTAL EVOLUTION OF RNA VERSUS DNA VIRUSES

2011

Based on their extremely high mutation rates, RNA viruses have been traditionally considered as the fastest evolving entities in nature. However, recent work has revealed that, despite their greater replication fidelity, single-stranded (ss) DNA viruses can evolve fast in a similar way. To further investigate this issue, we have compared the rates of adaptation and molecular evolution of ssRNA and ssDNA viruses under highly controlled laboratory conditions using the bacteriophages ΦX174, G4, f1, Qβ, SP, and MS2 as model systems. Our results indicate that ssRNA phages evolve faster than ssDNA phages under strong selective pressure, and that their extremely high mutation rates appear to be op…

Forced Retroevolution of an RNA Bacteriophage

2000

AbstractThe operator hairpin ahead of the replicase gene in RNA bacteriophage MS2 contains overlapping signals for binding the coat protein and ribosomes. Coat protein binding inhibits further translation of the gene and forms the first step in capsid formation. The hairpin sequence was partially randomized to assess the importance of this structure element for the bacteriophage and to monitor alternative solutions that would evolve on the passaging of mutant phages. The evolutionary reconstruction of the operator failed in the majority of mutants. Instead, a poor imitation developed containing only some of the recognition signals for the coat protein. Three mutants were of particular inter…

Intragenomic recombination between homologous regions of genes II and IV promotes formation of bacteriophage f1 miniphages.

1987

Restriction analysis of lambda EMBL3 background recombinants: occurrence of lambda phages carrying a head to tail oriented left arm DNA sequence.

1989

Eight representative recombinant background clones of lambda EMBL3 were analysed using KpnI, BamHI, SalI, EcoRI and HindIII digestion. We found that lambda EMBL3 carries its own left arm in the BamHI cloning site. In the way, recombinant molecules were found to be generated which can grow on Escherichia coli strain NM539. In all cases analysed, the left arm DNA was inserted in a head to tail orientation. Seven clones carried a restored BamHI site at the cos site-BamHI site connection. In the region where the inserted left arm and the right arm were ligated, BamHI cloning produces a large palindromic sequence consisting of two polylinkers. This BamHI site was incompletely cleaved in all case…