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Mating and Tetrad Separation of Chlamydomonas reinhardtii for Genetic Analysis
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Uptake of bacterial DNA by Chlamydomonas reinhardi

P F Lurquin, R M Behki

    Mutation Research
    |July 1, 1975
    PubMed

    Insights

    Bacterial DNA binds to Chlamydomonas reinhardi cells, with some irreversibly associated. Polycations enhance binding, but no DNA integration into host cells was observed.

    Area of Science:

    • Molecular Biology
    • Genetics
    • Microbiology

    Background:

    • Investigating interspecies DNA interactions is crucial for understanding gene transfer.
    • Chlamydomonas reinhardi serves as a model organism for studying algal biology and genetics.

    Purpose of the Study:

    • To determine if Escherichia coli DNA can interact with Chlamydomonas reinhardi cells.
    • To characterize the nature and extent of bacterial DNA binding to Chlamydomonas cells.

    Main Methods:

    • Incubation of Chlamydomonas reinhardi (wild-type and CW15 mutant) with [3H]DNA from Escherichia coli.
    • DNAse sensitivity assays to assess DNA integrity.
    • Treatment with polycations (DEAE-dextran, poly-L-lysine, poly-L-ornithine) to study binding enhancement.
    • Analysis of acid-insoluble radioactivity and DNA molecular weight.

    Main Results:

    • Escherichia coli [3H]DNA bound to Chlamydomonas cell walls (wild-type) and membranes (CW15 mutant).
    • Binding was largely DNAse-sensitive, with a small fraction irreversibly associated.
    • Polycations significantly increased irreversible DNA binding.
    • Chlamydomonas cells, particularly CW15, degraded bacterial DNA; wild-type cells showed minimal degradation.
    • Irreversibly bound DNA was mainly oligonucleotides; no integration into Chlamydomonas high molecular weight DNA was detected.

    Conclusions:

    • Chlamydomonas reinhardi cells can bind and partially retain bacterial DNA.
    • The process involves DNA degradation and reutilization of released nucleotides, not direct integration.
    • Polycations can enhance DNA association with Chlamydomonas cells.

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