Saturday, March 24, 2012

DNA Sequencer on USB

DNA Sequencer on USB
DNA sequencing is the process used to find the exact genetic makeup of human beings as well as other living organisms. Since it first became possible in the 1970s, scientists have been working to make the process less laborious, more accurate and less expensive. The nanopore technology is one such evolving procedure. The UK firm Oxford Nanopore Technologies has made a lot of headway with it since the company's inception in 2005. Most recently, Oxford Nanopore has announced a disposable miniature DNA sequence, the MinION. Using nanopore based technology, it promises to be faster as well as portable.
What is the MinION
The MinION resembles a USB memory stick. It draws power through the USB port of a computer. It also runs the computer analysis on the connected computer. This new device can sequence tiny bacterial and viral genomes in a matter of seconds. DNA is double stranded and the strands are held together by the bonds between their base pairs. The MinION can sequence such 150 million base pairs within six hours.
How does the MinION work
The mini sequencer is made up of a sensor chip, an Application Specific Integrated Circuit and nanopores. Nanopores are organic molecules embedded in a polymer membrane and containing very small pores or holes. The DNA can be threaded through them in the manner of stringing beads. Similar to laboratory tests, the MinION accepts blood, plasma and serum samples for analysis. Once it is plugged into the USB port of a laptop or desktop, it becomes a self contained sequencing device.
The MinION analyzes DNA using a strand sequencing technique. An enzyme in the electrophysiological fluid attracts the DNA strand and unlocks its double helix structure. One strand enters the nanopore and the other returns to the fluid. The enzyme also ensures that the single DNA strand passes through the nanopore one base pair at a time. Thus the sequencing proceeds and the MinION distinguishes between the four nucleobases which encodes genes in DNA.


Why is the MinION more viable
  1. For so long, DNA analysis required the DNA to be sliced into tiny pieces despite the percentage of error involved. Now the nanopore based technology has rid us of this necessity. DNA strands pass intact through nanopores on the sensor chip for sequencing. Hence they can be reutilized for analysis and the errors that chopping DNA introduced is also avoided.
  2. DNA strands pass through nanopores base pair by base pair and their speed of passage can be controlled. Slower passage rate yields more accurate results.
  3. Compared to other time-consuming sequencing processes, the MinION does not involve DNA amplification and is thus much faster. It has a maximum working life of six hours.
  4. Devised in the form of a USB memory stick, the MinION is a portable item and can prove useful for small scale analyses.

According to Oxford Nanopore, the MinION will be commercially available on the market by the year end at a retail price of $900. For now, it is intended for short sequencing jobs like pathogen identification and genetic mutation screening. However the present success and the continual ongoing research promise the possibility of sequencing larger genomes with the MinION in future. It can also eventually make DNA sequencing universally accessible.
About the author: Margaret is a blogger by profession. She loves writing on environment and technology. Beside this she is fond of books. She recently did an article on Gizmowatch. These days she is busy in writing an article on frii.

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