196:, is designed to interrupt a gene in such a way that it causes maximal genetic havoc. Specifically, the transposon contains signals to truncate the expression of an interrupted gene at the site of the insertion and then restart the expression of a second truncated gene. This method has been used to identify
80:. If such a phenotype is found then it can be assumed that the insertion has caused the gene relating to the usual phenotype to be inactivated. Because the sequence of the transposon is known, the gene can be identified, either by sequencing the whole genome and searching for the sequence, or by using the
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The inactivation of a gene by inserting a fragment of DNA into the middle of its coding sequence. Any future products from the inactivated gene will not work because of the extra codes added to it. An example is the use of pBR322, which has genes that respectively encode polypeptides that confer
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that tend to integrate their DNA in genetically unfavorable locations, the severity of any ensuing mutation depends entirely on the location within the host's genome wherein the viral DNA is inserted. If the DNA is inserted into the middle of an essential gene, the effects on the cell will be
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and cause the cell to begin replication, causing unchecked cell proliferation while allowing the viral gene to be replicated. After many replications where the viral gene stays latent tumours begin to grow. These tumours are normally derived from one
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Because many viruses integrate their own genomes into the genomes of their host cells in order to replicate, mutagenesis caused by viral infections is a fairly common occurrence. Not all integrating viruses cause insertional mutagenesis, however.
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Insertional mutagenesis is possible whether the virus is of the self-inactivating types commonly used in gene therapy or competent to replicate. The virus inserts a gene (known as a viral oncogene) normally near the cellular myc (c-myc)gene. The
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Alteration of different genes will have varying effects on the cell. Not all mutations will significantly affect the proliferation of the cell. However, if the insertion occurs in an essential gene or a gene that is involved in
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resistance to ampicillin and tetracyclin antibiotics. Hence, when a genetic region is interrupted by the integration of pBR322, the gene function is lost but new gene function (resistance to specific antibiotics) is gained.
162:(like the human thymus). This viral gene insertion is also known as a promoter insertion as it drives the expression of the c-myc gene. There is an example of an insertional mutagenesis event caused by a
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is an example of a virus that causes disease by insertional mutagenesis. Newly hatched chicks infected with the Avian leukosis virus will begin to form tumours that will begin to appear in their
133:, the insertion may compromise the viability of the cell or even cause the cell to replicate interminably – leading to the formation of a tumor, which may become cancerous.
117:, the promoter's corresponding gene may be over-expressed – leading to an overabundance of its product and altered cellular activity. If the DNA is inserted into a gene's
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Ivics Z, Izsvák Z (2004). "Transposable elements for transgenesis and insertional mutagenesis in vertebrates: a contemporary review of experimental strategies".
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An alternative strategy for insertional mutagenesis has been used in vertebrate animals to find genes that cause cancer. In this case a transposon, e.g.
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Some DNA insertions will lead to no noticeable mutation. Historically, lentiviral vectors included strong viral promoters which had a side effect of
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gene is normally turned off in the cell; however when it is turned on it is able to push the cell into the
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Carlson CM, Largaespada DA (July 2005). "Insertional mutagenesis in mice: new perspectives and tools".
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of the organism being studied. Mutants generated by this method are then screened for any unusual
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can have equally drastic effects. Likewise, if the viral DNA is inserted into a
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in the human genome where it causes
Fukuyama-type muscular dystrophy.
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258:"Designing Lentiviral Vectors for Gene Therapy of Genetic Diseases"
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32:. Such insertional mutations can occur naturally, mediated by
444:. Methods Mol. Biol. Vol. 260. pp. 255–76.
72:is allowed to integrate at random locations in the
54:This is a technique used to study the function of
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109:drastic. Additionally, insertion into a gene's
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256:Poletti, Valentina; Mavilio, Fulvio (2021).
487:at the U.S. National Library of Medicine
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28:in DNA by the addition of one or more
495:Diagram at gene-technology-online.com
181:engineering where a plasmid (such as
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84:to amplify specifically that gene.
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314:: CS1 maint: date and year (
88:Virus insertional mutagenesis
50:Signature-tagged mutagenesis
44:Signature tagged mutagenesis
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373:"Insertional inactivation"
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450:10.1385/1-59259-755-6:255
226:Site-directed mutagenesis
154:cell (clonal in origin).
82:polymerase chain reaction
489:Medical Subject Headings
175:Insertional inactivation
170:Insertional inactivation
485:Insertional+mutagenesis
442:Mobile Genetic Elements
177:is a technique used in
98:insertional mutagenesis
69:Drosophila melanogaster
22:insertional mutagenesis
231:Transposon mutagenesis
131:programmed cell death
216:Insertion (genetics)
211:Directed mutagenesis
156:Avian leukosis virus
127:cellular replication
24:is the creation of
160:bursa of Fabricius
348:"Recombinant DNA"
275:10.3390/v13081526
106:gammaretroviruses
18:molecular biology
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221:PCR mutagenesis
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194:Sleeping Beauty
179:recombinant DNA
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164:retrotransposon
119:enhancer region
111:promoter region
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62:such as the
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515:Mutagenesis
152:transformed
38:transposons
504:Categories
383:2010-04-11
358:2010-04-11
238:References
147:cell cycle
78:phenotypes
60:transposon
30:base pairs
284:1999-4915
198:oncogenes
115:repressor
64:P element
26:mutations
510:Genetics
468:15020812
419:15995698
302:34452394
268:(8): 5.
204:See also
150:mutated/
143:G1 phase
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293:8402868
262:Viruses
145:of the
34:viruses
491:(MeSH)
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183:pBR322
74:genome
423:S2CID
139:c-myc
56:genes
464:PMID
454:ISBN
415:PMID
316:link
298:PMID
280:ISSN
58:. A
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