Related Experiment Video

Updated: Aug 15, 2026

Following Cell-fate in E. coli After Infection by Phage Lambda
06:10

Following Cell-fate in E. coli After Infection by Phage Lambda

Published on: October 14, 2011

State of prophage Mu DNA upon induction

E Ljungquist, A I Bukhari

    Proceedings of the National Academy of Sciences of the United States of America
    |August 1, 1977
    PubMed

    Insights

    Bacteriophage lambda (λ) DNA excision differs from bacteriophage Mu (μ) DNA replication. Unlike lambda, Mu DNA replicates in situ, generating active forms for integration into host DNA, a mechanism potentially shared by transposable elements.

    Area of Science:

    • Molecular Biology
    • Microbiology
    • Genetics

    Background:

    • Bacteriophage lambda (λ) integration and excision follow the Campbell model, involving specific att sites.
    • Bacteriophage Mu (μ) is a temperate bacteriophage with a distinct replication and integration mechanism.
    • Understanding prophage induction mechanisms is crucial for comprehending viral life cycles and genetic element dynamics.

    Purpose of the Study:

    • To compare the DNA excision and replication processes of prophage lambda (λ) and prophage Mu (μ) upon induction.
    • To elucidate the mechanism of prophage Mu (μ) DNA replication and integration within the host genome.
    • To investigate potential similarities between Mu (μ) replication and the behavior of other transposable elements.

    Main Methods:

    • Utilizing restriction endonuclease digestion and agarose gel electrophoresis to analyze host-prophage DNA junctions.
    • Employing Southern blotting and hybridization with radiolabeled phage DNA for sensitive detection of specific DNA fragments.
    • Monitoring the disappearance of phage-host junction fragments and the appearance of att site fragments during lambda (λ) induction.

    Main Results:

    • Prophage lambda (λ) induction resulted in the disappearance of phage-host junction fragments and the appearance of an att site fragment, consistent with excision.
    • No such excision was observed for prophage Mu (μ); Mu-host junction fragments remained intact throughout the lytic cycle.
    • Mu (μ) DNA underwent extensive replication in situ, with evidence of multiple integrations into the host DNA.

    Conclusions:

    • Prophage Mu (μ) does not rely on excision for induction; instead, it replicates in situ.
    • Mu (μ) DNA replication generates forms active in integrative recombination with the host DNA.
    • The in situ replication and integration mechanism of Mu (μ) may be a conserved strategy among many transposable elements.

    More Related Videos

    Understanding the Impact of Temperate Bacteriophages on Their Lysogens Through Transcriptomics09:23

    Understanding the Impact of Temperate Bacteriophages on Their Lysogens Through Transcriptomics

    Published on: January 5, 2024

    Precise Phage Mutagenesis with NgTET-Assisted CRISPR-Cas Systems10:52

    Precise Phage Mutagenesis with NgTET-Assisted CRISPR-Cas Systems

    Published on: October 14, 2025

    Related Concept Videos

    Lytic Cycle of Bacteriophages01:30

    Lytic Cycle of Bacteriophages

    Bacteriophages, also known as phages, are specialized viruses that infect bacteria. A key characteristic of phages is their distinctive “head-tail” morphology. A phage begins the infection process (i.e., lytic cycle) by attaching to the outside of a bacterial cell. Attachment is accomplished via proteins in the phage tail that bind to specific receptor proteins on the outer surface of the bacterium. The tail injects the phage’s DNA genome into the bacterial cytoplasm. In the lytic replication...
    Lysogenic Cycle of Bacteriophages00:43

    Lysogenic Cycle of Bacteriophages

    In contrast to the lytic cycle, phages infecting bacteria via the lysogenic cycle do not immediately kill their host cell. Instead, they combine their genome with the host genome, allowing the bacteria to replicate the phage DNA along with the bacterial genome. The incorporated copy of the phage genome is called the prophage. Some prophages can re-activate and enter the lytic cycle. This often occurs in response to a perturbation, such as DNA damage, but can also transpire in the absence of...
    Transduction01:16

    Transduction

    Among the three main modes of HGT—transformation, conjugation, and transduction—transduction is unique in that it is mediated by bacteriophages, or bacterial viruses.Transduction occurs in two ways. Generalized transduction occurs during the lytic cycle of a bacteriophage infection. In this process, bacteriophages infect bacterial cells, replicate within them, and ultimately cause cell lysis, releasing newly assembled virions. Occasionally, random fragments of the bacterial genome are...
    Viral Replication: Lytic Cycle01:20

    Viral Replication: Lytic Cycle

    Bacteriophages, or phages, are viruses that specifically infect bacteria. Among them, T-even bacteriophages, such as T4, exhibit a well-characterized lytic replication cycle in Escherichia coli (E. coli). This process ensures the rapid proliferation of the virus while ultimately leading to the destruction of the bacterial host.Attachment and DNA InjectionThe infection process begins with the recognition and binding of the T4 phage to the E. coli cell surface. Tail fibers of the phage...
    Viral Replication: Lysogenic Cycle01:16

    Viral Replication: Lysogenic Cycle

    The lysogenic cycle is a crucial viral replication strategy that allows bacteriophages to persist within host cells without immediately destroying them. This process is primarily observed in temperate phages, such as bacteriophage lambda (λ), which infects Escherichia coli. The cycle allows the viral genome to persist across bacterial generations while keeping host cells viable.Integration of the Viral GenomeUpon infection, bacteriophage lambda attaches to the bacterial surface and injects its...
    DNA Bacteriophages01:26

    DNA Bacteriophages

    Bacteriophages, or phages, are viruses that specifically infect bacteria, utilizing their genetic material to hijack host cellular machinery for replication. DNA bacteriophages employ single-stranded DNA (ssDNA) or double-stranded DNA (dsDNA) genomes. These phages exhibit diverse replication strategies and host interactions, influencing their ecological roles and applications in biotechnology and medicine.ssDNA BacteriophagesssDNA phages, with their small genomes, utilize unique strategies to...