Department of Biotechnology, University of Hyderabad, Hyderabad, India
Received date: 29/05/2015 Accepted date: 01/06/2015 Published date: 10/06/2015
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In any organism, to conduct studies genome-wide, genomic information is important. The knowledge of genome information helps scientists to find new genes, functional elements, expression profiles  and genetic changes  among different tissues of an organism. Hence, sequencing has gained demand which led to many different methods of sequencing. Sequencing refers to determining the exact order of nucleotides from short segments such as genes [3,4] or regulatory elements to entire genome [5-9]. In 1973, very first time, Maxam and Gilbert introduced laboratory intensive sequencing method based on chemical modification of DNA. Due to involvement of hazardous chemicals in Maxam and Gilbert method, high efficient first generation sequencing called Sanger sequencing or chain termination method has gained popularity and it was the first standard method of sequencing developed in 1975. It uses dye labeled nucleotides and capillary electrophoresis in contrast to radioactive labeled nucleotides in Maxam and Gilbert method. Using this technology, after thirteen years of effort, human genome project was completed in 2003. To reduce the time and cost involved in Sanger method, there was an investigation for new methods called second generation or Next generation sequencing (NGS) technologies  involving less cost and reduced time. Next generation sequencing (NGS) technology came into market around ten years ago. The development of Next generation sequencing (NGS) technology in the last decade has had tremendous impact on the way the scientific research and clinical investigations are being carried out [11,12]. These improvements in NGS technology has led to reduction of time and cost per base and increase in length of read i.e., Sequencing is done in parallel and massive scale. Several NGS methods have been in use among which the three most commonly used are such as Illumina (Sequencing-by-synthesis) , Roche 454 (Pyrosequencing), and SOLiD (Sequencing-by-ligation). The other popularly used NGS technique next to these three methods is ion torrent technique .
The applications of NGS span numerous research areas pertinent to biology [15-17]. Comparative studies at genome level which were impossible before are imaginable now and can be conducted in small span of time . It helps to sequence whole genome in less time on a large scale at low cost. The NGS technology has been applied to variety of research areas which include whole exome studies [19,20], personalized medicine , mutational studies [22,23], studying genetic disorders , annotating new sequences [25,26], Identification of genes and regulatory elements involved in pathological processes [27-30], forensic research, agricultural genomics , environmental genomics  and diagnosis of diseases at molecular level [33-35]. Detail analysis of transcriptome is now possible with NGS. The RNA studies [36-38] have been possible not only on mRNA but also on tRNA and rRNA. The research is currently into developing third generation sequencing methods [39-43] which reduce the costs involved and time consumed.
With the discovery of large amount of genetic information, the need for computational methods [44-48] to manage , retrieve, process, and analyze sequence data [50-52] and ensure correct interpretation  are in high demand.