Development of New DNA Analysis Method for Detecting Foreign (non-Japanese) Eel

TOKYO, March 28, 2012 /PRNewswire/ -- The Shizuoka Institute of Science and Technology has developed a "DNA batch test," a method of DNA analysis able to detect and determine the mixing rate of one foreign species eel from 1,000-10,000 specimen batches supposed to be all Japanese (Anguilla japonica) eels, with high accuracy and low cost.  The innovative method was developed jointly in participation with Life Technologies, Hikari Corporation, Obihiro University of Agriculture and Veterinary Medicine, Cohki Co., LTD and Atsumi Co., LTD.  

Through a small tissue sample, the test can determine the species type and number of species within a given test batch.  The reagent cost per sample is reduced to about JPY10, which allows the option for it to be used as a method of quality control for actual products.  In line with rising prices of domestic eels, preparation for field test appraisal is underway. 

Last summer a study was conducted using the method on kabayaki (grilled eel) eel specimens in Tokyo by the Shizuoka Institute of Science and Technology, which included a sample group of 100 Japanese and nonindigenous eel specimens.  The study found five nonindigenous specimens, which were classified under European species (Anguilla anguilla), and labeled as from China.

The DNA batch test method can also be applied to all types of common food products, and the Shizuoka Institute of Science and Technology will present this method during the meeting of the Japanese Society of Fisheries Science this spring held at the Tokyo University of Marine Science and Technology on March 29.

There has been increasing concern over soaring prices of Japanese eel due to extremely low catch numbers in recent years.  While the cause is unknown, and this year in particular held record low numbers, nonindigenous elvers and adult farmed eels from Australia and other nations are being imported to address the issue.  As a result there exists a high possibility of confusion when identifying a particular species type.

In 1997 damage was widespread among eel farmers.  As a countermeasure for "species camouflage," in which foreign elvers were feigned as Japanese, the Shizuoka Institute of Science and Technology began development of a method of DNA analysis accounting for all types of eel specimens, which was put to commercial use in 1999.  In a test of 100 kabayaki eels conducted in Tokyo in 1998, nearly two-thirds were found to be nonindigenous.  The method has since been employed by many inspection agencies throughout Japan to identify species and species camouflage in production areas of Japanese eels.  Species camouflage was at its peak in eel production sites throughout Japan in 2006.  At the time, even the Shizuoka Institute of Science and Technology, which helped develop the DNA analysis method, was asked by local authorities to aid in conducting tests in local areas together with private inspection agencies.

Previous methods tested individual DNA specimens, initially incurring reagent costs of around JPY500 yen (US $6) per one sample; however, additional procedures required by private inspection agencies raised the actual cost to approximately JPY10,000-30,000.  So in 2009, the Shizuoka Institute of Science and Technology developed the "Foreign species allele-specific PCR (AS-PCR)," which was responsive only to testing eel DNA that is nonindigenous to Japan.  In addition, they developed and put into practical use a method of analyzing of up to 100 specimens at a time using the normal PCR response device, all of which dramatically reduced the cost of testing to one percent of the previous cost.  Details of the method were submitted to the journal of the Japanese Society of Fisheries Science and published in the September 2011 issue.

Following that, under a program of Strategic Research Foundation Grant-aided Project for Private Universities from Japan's Ministry of Education, Culture, Sports, Science, and Technology, a project proposed by the Shizuoka Institute of Science and Technology was accepted and a real time PCR (developed by Life Technologies, ABI7500FAST) was utilized, which led to the formation of a method of high sensitivity and fast determination DNA analysis.  Taking the opportunity, the AS-PCR method was applied, and by utilizing the advantages of the high sensitivity device, DNA testing of Japanese and nonindigenous eels in multi-specimen batches of 1,000-10,000 was made possible.  Costs per reagent per one sample required for the analysis dropped to nearly JPY10 yen (US$0.12), which is almost equal to that for the DNA extraction only.

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Media Contacts:

Toshihiro Tsuneyoshi
[email protected]
Tel: 0538-45-0164
Department of Materials & Life Science, Shizuoka Institute of Science and Technology

Yoriko Obokata
Life Technologies Japan
[email protected]

Suzanne Clancy, Ph.D.
Life Technologies
[email protected]
760.717.8294

SOURCE Life Technologies