Gene Trap Essay

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Gene traps are the plasmid or retrovirus-based vectors having a reporter gene that is only expressed when integrated in a functional gene. They were originally developed for the study of insertional mutagenesis in mouse. The gene traps were used to identify and characterize genes which were regulated by exogenous stimuli or during development process. The gene trap is a process which makes it possible to identify genes that gives rise to phenotypic effects when they are switched off, and also helps to analyze the effects of these genes in cells or complete organisms. The first step in the gene trap process is to integrate an artificially constricted DNA into a genome of a cell line, usually an embryonic stem (ES) cell line. To carry out this …show more content…
The sequence enables that the integrated co-transcribed construct is recognized as an exon during processing of hnRNA to mRNA, so that can be present in the mRNA. Third important sequence in the construct is polyadenylation or polyA signal. This results in the braking of mRNA at this point, instead of extending into the following exons of the concerned gene. This prevents the degradation of mutated mRNA. The artificial mRNA is therefore stable and the fusion protein therefore can be translated its presence is demonstrated. If the integration of the construct is linked to change in phenotypic expression, the next step is to identify the responsible genes. Since the sequence of reporter gene is now known the suitable methods (RACE, rapid amplification of cDNA ends) can be used to find out the sequence.

REPORTER GENES:
• The reporter genes helps to determine the function of the desired genes by fixing its coding region to the promoter region of the gene this helps the scientist to detect the gene's activity (production of protein), when the gene is activated, it synthesis the protein along with the reporter gene helping to detect when and where the gene is active in the genome. It helps to identify and explain the role of gene by identifying when and where the protein was produced hence called as reporter genes.
• since the promoter region of the gene is attached to the coding region the
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i. The concern of gene trapping bias against developmental process later stage. Mouse ES gene trapping technology depends on mouse ES cells for screening gene trapping mutations, the genes of interest have to be expressed in mouse ES cells in order for them to be trapped. It is seen that the developmental regulators in embryonic stage has been effectively mutated but the efficiency in adult stage is not very clear.

ii. Concerns of difference in splicing between reproductive tissue and embryonic tissues. The mutation of the gene trap does not become effective until the inserted vector is spliced together with the exon next to where the vector is inserted. Genes also have testis and ovary specific splicing sites; therefore it can also disrupt the testis and ovary isoforms.

iii. Concerns over gene specifically expressed in reproductive tissues. These genes are of much interest they raise the question of whether these genes expression pattern could still be trapped in mouse ES

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