Sadia Perween 2 Etal
Sadia Perween 2 Etal
Sadia Perween 2 Etal
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Anand Kumar
Bihar Agriculture University
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ABSTRACT
Transposable elements, found in almost all organisms, are short sequences of DNA that
have the ability to move from one location to the other locations in the genome.
Transposons make up 10% of eukaryotic genomes. They provide a means for genomic
change and variation, particularly in response to stress (McClintock’s stress
hypothesis).There is no known example of transposon playing a normal role in
Keywords development. They are called as selfish DNA and can be used as genetic markers, as
mutagens for transposon tagging and isolation of gene, as transformation vectors and as
transposons,
cloning vehicle. Transposons are potent forces of genetic change and have a significant
insertational
mutagenesis,
aspect in the evolution of many genomes. DNA transposons can be used as genetic tools to
transposon tagging introduce a piece of foreign DNA into any genome. They have been utilized for
transgenesis and insertional mutagenesis in diverse organisms, as these elements are not
Article Info generally dependent on host factors to facilitate their mobility. Thus, DNA transposons are
powerful tools to analyze the regulatory genome, study the development of embryo,
Accepted: identify genes and pathways involved in disease or pathogenesis of pathogens, and helps in
15 January 2020 gene therapy. Transposons are used for gene cloning since insertion of a transposon into a
Available Online: gene upsets its function which develops a visible mutant phenotype. When the DNA
10 February 2020
sequence of the transposon is known, it is possible to clone the disrupted gene by
employing the transposable element as a tag to locate the segment of DNA possessing the
element. Transposon tagging involves initiating transposition, screening for mutations
caused by transposon insertion, discovering the element responsible for the developed
mutation, and cloning the tagged gene.
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Class I transposons are used for tagging in The efficiency of transposon tagging at any
mammals and yeast, whereas; class II gene is decided by a number of factors. For a
transposons are most frequently used in transposon to be perfect for tagging purpose,
tagging schemes for bacteria and plants. there would be no preference for the
integration site in the host genome, but many
Regulation of Transposition transposons show some type of site
preference. The examples of preferences
It is essential to have a few methods for include C. elegans Tc1 element having a TA
controlling the frequency of transposition. dinucleotide target site(Rozenzweig et al.,
There are families of transposable elements 1983a and Liao et al., 1983) and Drosophila P
containing non autonomous controlling element preferentially inserting at the 5′-ends
elements that cannot produce transposase but of transcription units(Kidwell, 1994).
are mobile in the company of the transposase
produced by an "autonomous" family Transposition to linked sites
member. Similarly, two-element system is
mostly employed in transposon-tagging A characteristic of many transposons is their
techniques where a stable transposase source ability to transpose to linked sites making it
(e.g., a transposon immobile due to deletion useful for some types of screens, but in the
of one of its direct repeats) is employed to process makes random transposon
move nonautonomous elements. This system mutagenesis more strenuous. In some cases,
has the edge as once new insertions have been methods have been studied to identify
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phenotype. These individuals contain the effectively used to identify various gene
original mutation as well as a new transposon- expression patterns in different organisms,
induced allele of the same gene. like Arabidopsis and Drosophila.
The second type of directed mutagenesis Similarity exists between gene traps and
experiment is used in schemes where the enhancer traps but the transposon used here
transposon moves preferentially to linked lacks promoter and has reporter whose
sites on the chromosome. A mapped TE that expression requires the transposon to be
is linked to the gene of interest is mobilized. inserted downstream of the promoter of the
Insertions into the specified gene are expressed gene. RNA splicing-acceptor
identified in the M1, or the linked transposon sequences are introduced upstream of the
is allowed to mobilize in a wild-type coding region of the reporter gene to permit
background, followed by screening of M2 for fusion of the reporter gene to the tagged gene
mutations. if the transposon inserts into an intron.
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Transposon tagging strategies: from gene to remobilize the transposon and select for
to mutant excision phenomenon that fully disrupt the
gene.
Site-selected mutagenesis
It is concluded that the transposon tagging
Gene of known sequence is being inserted techniques are valuable and important for
with transposon and causes its mutation several reasons. They are aided to identify
leading to its null expression, which helps in and clone various genes having distinguished
identifying the function of the gene. phenotypes, and enhancer-trap and gene-trap
Homology study and expression pattern systems are used for screening genes based on
analysis are often used for the same purpose. their expression patterns.
In some cases, the original insertion does not Allen SE, Nowacki M (2017) Necessity is the
change gene function sufficiently to create a mother of invention: ciliates,
visible phenotype. Then, it becomes important transposons, and transgenerational
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Sadia Perween, Deepak Kumar and Anand Kumar. 2020. A Review on Transposons and its
Utilization as Genetic Tool. Int.J.Curr.Microbiol.App.Sci. 9(02): 1874-1884.
doi: https://doi.org/10.20546/ijcmas.2020.902.214
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