Transduction

Transduction is the process by which bacterial DNA is moved from one bacterium to another by a virus. It also refers to the process whereby foreign DNA is introduced into another cell via a viral vector. This is a common tool used by molecular biologists to stably introduce a foreign gene into a host cell's genome. The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... This article is about biological infectious particles. ... Viral vectors are a tool commonly used by biologists to deliver genetic material into cells inside a living organism or cultured in vitro. ... In biology the genome of an organism is the whole hereditary information of an organism that is encoded in the DNA (or, for some viruses, RNA). ...

When bacteriophages (viruses that infect bacteria) infect a bacterial cell, their normal mode of reproduction is to harness the replicational, transcriptional, and translation machinery of the host bacterial cell to make numerous virions, or complete viral particles, including the viral DNA or RNA and the protein coat. This article or section does not cite its references or sources. ... DNA replication. ... A micrograph of ongoing gene transcription of ribosomal RNA illustrating the growing primary transcripts. ... Translation is the second stage of protein biosynthesis (part of the overall process of gene expression). ... A common alternate meaning of virus is computer virus. ...

Lytic and lysogenic (temperate) cycles

Transduction happens through either the lytic cycle or the lysogenic cycle. The lytic cycle is one of the two cycles of viral reproduction, the other being the lysogenic cycle. ... Lysogeny is the fusion of the nucleic acid of a bacteriophage with that of a host bacterium so that the potential exists for the newly integrated genetic material to be transmitted to daughter cells at each subsequent cell division. ...

If the lysogenic cycle is adopted, the phage chromosome is integrated into the bacterial chromosome, where it can remain dormant for thousands of generations. If the lysogen (eg. UV light) is induced, the phage genome is excised from the bacterial chromosome and initiates the lytic cycle, which culminates in lysis of the cell and the release of phage particles.

The lytic cycle leads to the production of new phage particles which are released by lysis of the host.

Mistakes

However, the packaging of bacteriophage DNA is not fool-proof and at some low frequency, small pieces of bacterial DNA, rather than the bacteriophage genome, will be packaged into the bacteriophage genome. At the same time, some phage genes are left behind in the bacterial chromosome.

There are generally two types of mistakes that can lead to this incorporation of bacterial DNA into the viral DNA, leading to two modes of recombination.

Generalized transduction

If bacteriophages undertake the lytic cycle of infection upon entering a bacterium, the virus will take control of the cell’s machinery for use in replicating its own viral DNA. If by chance bacterial chromosomal DNA (instead of viral DNA) is inserted into the viral capsid used to contain the viral DNA, while this lytic pathway is proceeding, the mistake will lead to generalized transduction. The new virus capsule now loaded with part bacterial DNA is no longer infectious, but will still attempt to infect another bacterial cell. This article or section does not cite its references or sources. ... The lytic cycle is one of the two cycles of viral reproduction, the other being the lysogenic cycle. ... The lytic cycle is one of the two cycles of viral reproduction, the other being the lysogenic cycle. ...

When the new DNA is inserted into this recipient cell it can fall to one of three fates

• 1. The DNA will be absorbed by the cell and be recycled for spare parts.

• 2. If the DNA was originally a plasmid, it will re-circularize inside the new cell and become a plasmid again.

• 3. If the new DNA matches with a homologous region of the recipient cell’s chromosome, it will exchange DNA material similar to the actions in conjugation.

This type of recombination is random and the amount recombined depends on the size of the virus being used. Conjugation may refer to: Grammatical conjugation, the modification of runnign a verb from its basic form Latin conjugation, Spanish conjugation and The English verb, each with complex conjugation forms Marriage, relationship between two individuals In mathematics: Complex conjugation, the operation which multiplies the imaginary part of a complex number by... Recombination usually refers to the biological process of genetic recombination and meiosis, a genetic event that occurs during the formation of sperm and egg cells. ...

It is worth asking whether generalized transduction can occur by lysogenic phages. Two possible scenarios might be imagined to cause generalized transduction though literature references have not been found to confirm or dispute them:

• 1. A lysogenic phage whose site of integration is randomly chosen, which occasionally brings along adjacent DNA because of an erroneous excision process.
• 2. A lysogenic phage that goes into its lytic phase and randomly incorporates cell DNA.

Specialized transduction

The second type of mistake is called specialized transduction. If a virus removes itself from the chromosome incorrectly, it can leave part of the viral DNA in the chromosome. Some of the bacterial DNA can be packaged into the virion. Mistakes in this process of viral DNA going from the lysogenic to the lytic cycle lead to specialized transduction. There are three possible results from specialized transduction: Lysogeny is the fusion of the nucleic acid of a bacteriophage with that of a host bacterium so that the potential exists for the newly integrated genetic material to be transmitted to daughter cells at each subsequent cell division. ... The lytic cycle is one of the two cycles of viral reproduction, the other being the lysogenic cycle. ...

• 1. DNA can be absorbed and recycled for spare parts.

• 2. The bacterial DNA can match up with a homologous DNA in the recipient cell and exchange it. The recipient cell now has DNA from both itself and the other bacterial cell.

• 3. DNA can insert itself into the genome of the recipient cell as if still acting like a virus resulting in a double copy of the bacterial genes.

This type of recombination is not random and only small portions of genes are recombined.

Example of specialized transduction is λ phages in Escherichia coli. E. coli redirects here. ...

RNA, DNA

Viruses with RNA genomes are not able to package DNA and so do not usually make this mistake.

Upon lysis of the host cell, the mispackaged virions containing bacterial DNA can attach to other bacterial cells and inject the DNA they have packaged, thus transferring bacterial DNA from one cell to another. This DNA can become part of the new bacterium's genome and thus be stably inherited. Lysis (Greek lusis from luein = to separate) is the reduction of symptoms of a disease the dissolving of cells osmotic lysis chemical lysis viral lysis a dialogue of Plato about friendship (philia) This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same...

More general uses of the term

More generally, transduction is the process by which genetic material, e.g. DNA or siRNA, is inserted into a cell. Common techniques in molecular biology are the use of viral vectors (including bacteriophages), electroporation, or chemical reagents that increase cell permeability. Transfection and transformation are more common terms, although these sometimes imply expression of the genetic material as well. The structure of part of a DNA double helix Deoxyribonucleic acid, or DNA, is a nucleic acid molecule that contains the genetic instructions used in the development and functioning of all known living organisms. ... Small interfering RNA (siRNA) are a class of 20-25 nucleotide-long RNA molecules that interfere with the expression of genes. ... Molecular biology is the study of biology at a molecular level. ... Viral vectors are a tool commonly used by biologists to deliver genetic material into cells inside a living organism or cultured in vitro. ... This article or section does not cite its references or sources. ... Electroporation, or electropermeabilization, is a significant increase in the electrical conductivity and permeability of the cell plasma membrane caused by externally applied electrical field. ... Transfection describes the introduction of foreign material into eukaryotic cells. ... It has been suggested that this article or section be merged into Transfection. ... Gene expression, or simply expression, is the process by which the inheritable information which comprises a gene, such as the DNA sequence, is made manifest as a physical and biologically functional gene product, such as protein or RNA. Several steps in the gene expression process may be modulated, including the...

Discovery

Transduction was discovered by Norton Zinder and Joshua Lederberg at the University of Wisconsin-Madison in 1952. Norton Zinder (born November 7, 1928) is an American biologist famous for his discovery of genetic transduction. ... Joshua Lederberg speaking at a conference in 1997 Joshua Lederberg (born May 23, 1925) is an American molecular biologist who is known for his work in genetics, artificial intelligence, and space exploration. ... University of Wisconsin redirects here. ...

External links

• MeSH Genetic+Transduction
• Overview at ncbi.nlm.nih.gov
• http://www.med.umich.edu/vcore/protocols/RetroviralCellScreenInfection13FEB2006.pdf (transduction protocol)
• Generalized and Specialized transduction at sdsu.edu
• Transduction at eMedicine Dictionary