transduction

transduction, in genetics: see recombination.

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transduction [tranz′dək·shən]

(microbiology)

Transfer of genetic material between bacterial cells by bacteriophages.

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Transduction (bacteria)

A mechanism for the transfer of genetic material between cells. The material is transferred by virus particles called bacteriophages (in the case of bacteria), or phages. The transfer method differentiates transduction from transformation. In transformation the genetic material (deoxyribonucleic acid) is extracted from the cell by chemical means or released by lysis. See Bacterial genetics, Bacteriophage, Deoxyribonucleic acid (DNA), Transformation (bacteria)

The transduction mechanism has two features to distinguish it from the more usual mechanism of gene recombination, the sexual process. The most striking feature is the transfer of genetic material from cell to cell by viruses. The second feature is the fact that only a small part of the total genetic material of any one bacterial cell is carried by any particular transducing particle. However, in general transduction, all of the genetic material is distributed among different particles.

Transduction is not accomplished by all bacteriophages. It is done by some that are classified as “temperate.” When such temperate bacteriophages infect sensitive bacteria, some of the bacteria respond by producing more bacteriophage particles. These bacteria donate the transducing material. Other bacteria respond to the infection by becoming more or less permanent carriers of the bacteriophage, in a kind of symbiotic relationship; these are called lysogenic bacteria. Bacteria in this latter class survive the infection, and it is among these that transduced cells are found. The proportion of bacteria in any culture that responds to infection in either manner can be influenced by the particular environment at the time of infection. See Lysogeny

Certain phages carry out a more restricted kind of transduction. They carry only a specific section of bacterial genetic material; they transduce only a few genes. Retroviruses carry out specific or restricted transduction. It has long been known that these viruses can cause the formation of tumors (oncogenesis) in animals. It is now known that these viruses exchange a small portion of their genome for a mutant cellular gene that has a role in gene regulation or replication. These viruses carrying mutant genes infect cells, causing them to be transformed into tumor cells. See Animal virus, Retrovirus