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Last updateSun, 15 Jul 2018 8pm
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Bioprinting Technology to Control the Number of DNA Molecules in Units of One

∼ Contributing to high genetic testing accuracy using a reference material containing a known number of DNA molecules ∼

This news release refers to a joint effort between Ricoh Company, Ltd., the National Agriculture and Food Research Organization (NARO), and FASMAC of the Nippon Flour Mills Group. The three organizations have collaborated using bioprinting technology to make a new reference DNA material in which the absolute number of the DNA molecules is controlled in units of one. The reference material can be used in the quality control of genetic testing instruments and reagents. A reference material contains quantitatively determined ingredients and is used as a measurement standard, but no other reference material contains DNA molecules whose quantity is controlled in units of one. The three organizations have developed a new method to produce reference DNA material, which enables production of reference materials suitable for genetic testings to detect specific DNAs, as in the inspection of GMO foods, cancers, and infections. The new reference DNA materials will increase the reliability of the tests.
These achievements will be announced in the Bio International Convention in Boston, USA (June 4-7th) and Biotech Japan 2018 in Tokyo, Japan (June 27-29th).

Polymerase chain reaction (PCR) is widely used in genetic testing. Reportedly, a PCR-based method can detect even a single DNA molecule by amplification. This high sensitivity is a useful factor and the method is widely used in inspections of GMO (genetically modified organism) foods, cancers, and infections. Some severely strict inspections are not allowed overlook any of the specific DNA sequences (target genes). Thus, it is important for testing laboratories to implement thorough quality control over the testing equipment, the reagents, and the detection method as a whole. Some companies and research institutes have delivered reference material whose DNA types and densities are prescribed, but they are of high densities i.e. the number of DNA molecules is prescribed in mol (one mol is equivalent to 6.02×1023 DNA molecules). For use in low-density tests at an accuracy of 100 molecules or less, the reference material generally must be diluted.
Thus, errors can occur in DNA molecule densities during the diluting process. The diluted samples may contain more DNA molecules than prescribed, or conversely no DNA molecules at all, when the required number of DNA molecules is less than ten.
NARO has developed a genetically modified yeast that contains target gene sequences. The genetically modified yeast is injected using Ricoh’s bioprinting technology onto wells on a plate, with the number of molecules determined and controlled in units of one. The resulting reference DNA material (reference DNA plate) contains the prescribed number of DNA molecules of a specific gene sequence. It has been impossible to count the number of DNA molecules directly but it can now be indirectly counted by handling cells containing the target gene sequence (yeast, in this example). Using bioprinting technology to handle the cells enables reference DNA material to be produced efficiently.
NARO, FASMAC, and Ricoh have conducted a joint evaluation using real-time PCR; they have demonstrated that materials can be produced with an unprecedented calibration curve (a graph of measurement results based on reference material, which sets the standard for measuring material densities) in the low-density range of 1 to 1,000 molecules.
For the technology component of bioprinting, which uses inkjet technology, Ricoh has been developing an inkjet head to deliver cells stably and a technology to count the number of cells in the delivered droplets.
NARO and FASMAC have long been dealing with technological development regarding genetic testings, development of a single-molecule reference DNA material, and international standardization of test methods, particularly in the area of GMO food inspection.
The joint development effort has resulted in a new production method and a new reference DNA material, which will enable stricter quality control of genetic testing instruments, reagents, and genetic testing methods. The material will be useful in improving the accuracy of GMO food inspections and preventing cancers and infections from being overlooked. Furthermore, the technology will contribute to solving larger social issues.
www.ricoh.com

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