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From gene duplication to cancer: How do amplified fragments affect our health?
In molecular biology, an amplicon is a segment of DNA or RNA that is the source or product of an amplification or replication event. The formation of the amplified fragment can be artificial, such as using the polymerase chain reaction (PCR) or ligase chain reaction (LCR), or it can be the result of natural gene duplication. In this context, amplification refers to the process of producing one or more copies, particularly of an amplified fragment.
The presence of amplicon fragments has important applications in research, forensics, and medicine, including detecting and quantifying infectious diseases, identifying human remains, and extracting genotypes from human hair.
Natural gene duplications play a key role in evolution and have been implicated in the development of several human cancers, including primary mediastinal B-cell lymphoma and Hodgkin lymphoma. In this context, the amplicon can refer to both the chromosomal DNA fragment that has been sheared, amplified, and reinserted into the genome, and the extrachromosomal DNA fragment known as the doublet, each of which may consist of one or more Multiple gene composition.
Amplification of the genes encoded in these amplified fragments usually increases the transcription of these genes, ultimately leading to increased production of related proteins.
Structure of the amplified fragment
In general, the structure of the amplified fragment can be a direct repeat (head to tail) or inverted repeat (head to head or tail to tail) of the gene sequence, and can be a linear structure or a circular structure. The circular amplicons consist of imperfect inverted repeats, which are thought to originate from the precursor linear amplicons. The length of the amplified fragment during artificial amplification is determined by the purpose of the experiment.
Technology of amplifying fragments
Analysis of amplified fragments has become feasible due to the development of amplification methods, such as polymerase chain reaction (PCR). In addition, with the rise of cheaper and higher-throughput gene sequencing technologies, such as the famous Ion Torrent semiconductor sequencing, these technologies have enabled more in-depth studies of amplified fragments in genome biology and genetic research.
Using the 16S rRNA gene, scientists can classify bacteria by comparing the sequence of the amplified fragment with known sequences, and in the fungal domain this also applies to the 18S rRNA gene and the ITS1 noncoding region.
Regardless of the method chosen to amplify the amplicons, some technique must be used to quantify the amplified products. These techniques generally include a capture step and a detection step, although the specific implementation of these steps depends on the individual detection method. For example, the Amplicor HIV-1 Monitor Assay (RT-PCR) can identify HIV in plasma, and the HIV-1 QT (NASBA) is used to measure the viral load in plasma by amplifying fragments of HIV RNA.
Application of amplified fragments
PCR technology can be used to detect gender from human DNA samples. The Alu element insertion sites were selected, amplified and size assessed, and sex determination utilized AluSTXa and AluSTYa on chromosomes X and Y to reduce the possibility of error. The inserted chromosome produces larger fragments when amplified, with males showing two DNA amplification fragments and females only one.
For diagnosing tuberculosis, the LCR technique will target a sequence containing protein antigen B, using four oligonucleotide primers, two for the sense strand and two for the antisense strand. These primers bind in close proximity to each other, forming sections of double-stranded DNA that, once separated, can become targets for future replication, and the products can be detected by microparticle enzyme immunoassay (MEIA).
As research on amplified fragments deepens, our understanding of genes continues to increase. In the future, what new changes will there be in the application of amplified fragments in treating diseases and understanding evolution? Will it enable us to find more answers to the mysteries of health?
