Targeted sequencing is a method to isolate, enrich and sequence a group of target genes or genome regions. This method enables researchers to focus time, cost and data analysis on specific regions of interest (target regions, genes), and use less data to obtain higher sensitivity and accuracy, so as to achieve rapid screening of mutation sites. These target regions usually include exome (the protein coding part of the genome), specific genes of interest (customized content), and target regions in genes or mitochondrial DNA.
FBI seq (Foreground and Background Integrated genotyping by sequencing) is not sequencing by the US Federal Bureau of Investigation, but genotyping sequencing integrating foreground and background. As the name implies, this technology realizes the detection and selection of foreground genes and genetic background at the same time. The selection of foreground and background is two very important steps in molecular breeding. At present, breeders often need to carry out these two steps independently: first, screen foreground target sites, and then develop a large number of probes/bait/PCR primers to detect background genotypes. These time-consuming and costly preparations greatly delay the start of breeding projects.
The genotype detected by the method of high depth re sequencing is undoubtedly the most comprehensive, but at present, the cost of application in animal and plant breeding is too high, especially for those species with complex and huge genomes. As mentioned in the previous issue, researchers usually use a unique library construction method to carry out simplified genome sequencing (RAD seq), thereby reducing the cost of genotyping. However, the amount of simplified genome data is generally only 1~10% of the total genome, and a lot of information is still lost. Pool sequencing is also an effective way to reduce the cost of population research, but it cannot analyze individuals, which has little effect on animal and plant breeding.
The layman who hears "gene chip" for the first time can easily connect it with the electronic chip of industrial integrated circuit. In fact, except that they all use micro technology to make the appearance more similar, they have nothing to do with each other and are purely porcelain. Gene chip, also known as DNA chip, biochip or DNA microarray, is based on the principle of specific interaction between molecules, integrating discontinuous analysis processes on the surface of solid phase chips such as silicon or glass, to achieve accurate, rapid and large detection of cells, proteins, genes and other biological components. According to specific scientific research and application contents, gene chips can be subdivided into microarray comparative genomic hybridization (a-CGH) chips, microRNA chips, SNP chips, expression profile chips, DNA methylation chips and chromatin immunoprecipitation chips.
Under the popular understanding, in our daily life, we usually need to find a landmark building to get a location when going to a certain place. Similarly, the search and location of genes or sites distributed on genome chromosomes also need to be guided by markers, so molecular markers are identified by nucleotides and other molecules. Polymorphism is the most important feature of markers. As the name implies, polymorphism is a variety of states, that is, diversity. A gene/locus can be distinguished and compared only when it is in different states and has differences in different materials. That is the meaning of molecular markers.