Next-generation sequencing (NGS) are high throughput methods that have greatly simplified genome sequencing. These rapid and cost-effective methods are based on the common principle that the genome to be sequenced is fragmented into multiple pieces, which are sequenced in parallel. They are useful tools for sequencing whole genomes of various organisms from microbes to humans. The advent of these nucleic acid sequencing methods has enabled genome sequencing of 65,000 organisms until now and more are soon to be added to this list. Using NGS technologies, the entire human genome can be sequenced in a single day. When NGS technologies were not developed, achieving the same thing (i.e. Human Genome Project) using the Sanger sequencing technique took an entire decade and billions of dollars. This gives the idea of the tremendous sequencing capacity of NGS technologies. They are invariably the method of choice for nucleic acid sequencing these days. It is now possible to tackle difficult research questions with ease using NGS. Genomes are the blueprints of the information that is necessary for cellular functioning. Any deviation in the genome sequence called mutations may change the course of this information leading to defective cellular processes, which in turn may contribute to various diseases. For example, genetically inherited disorders or different types of cancers are the consequence of alterations in the original genomic information. Hence, an in-depth analysis of the genome would be useful to understand the disease pathology. Genomes are huge in length therefore sometimes, sequencing of only the coding region of the genome is required. Sequencing only protein- coding regions of the genome is called exome sequencing. Transcriptomics or RNA-seq involves the sequencing of expressed RNAs. mRNA-seq analysis of diseased and healthy individuals may provide information about gene-expression differences between two conditions, which may help to correlate these gene expression differences to disease. Some of these genes may serve as markers for disease diagnosis. Studying gene expression regulation is also one of the research areas. Regulation of the gene expression occurs by either epigenetic modification which involves DNA methylation or histone modification. Another way by which a gene is regulated is by binding transcription factors. High throughput sequencing technologies may be helpful to study epigenome level changes, gene silencing, or expression mechanisms where epigenetic modifications play a role. Delineation of DNA binding sites of certain proteins e.g., transcription factors, histones, etc. is helpful to understand gene regulation mechanisms. Mapping of the transcription factor binding sites on the genome is done by Chip-seq. Moreover, NGS is extremely useful in screening the microbial population diversity in clinical or environmental samples e.g., human gut microbiome analysis, oral flora, soil, river water microflora examination, etc., and their alteration in diseases or environmental pollution. It is possible to sequence and identify the unculturable microorganisms by NGS. With these varieties of different applications, it is evident that NGS technologies are proving to be a game-changer in the research field. The application of high throughput sequencing technologies in research and industry will continue to increase in the future and with it, the demand for skilled manpower will also increase.
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