Biomedical subjects

Shoko Tokishita

Publications and source records attributed to Shoko Tokishita.

3 recordsLinked to original sources

PubMed2006

A detection method of CryIAc protein for identifying genetically modified rice using the lateral flow strip assay.

We examined the lateral flow strip assay for identifying unauthorized genetically modified (GM) rice. The GM rice expresses the Bacillus thuringiensis (Bt) toxin, CryIAc protein, which confers tolerance to insects. The recombinant CryIAc protein was prepared from the inclusion bodies of an E. coli. strain into which the CryIAc gene had been inserted, using gel filtration chromatography. The lateral flow strip assay for the identification of GM cotton which also expresses CryIAc protein, was applied to unpolished rice and polished rice spiked with recombinant CryIAc protein. The spiked recombinant CryIAc protein was clearly detected at the level of 0.012 microg/g in both the unpolished and polished rice. After loading of the extract on the strip, a 60 -minute stand time is necessary to clearly detect CryIAc protein. The detection limit was approximately 12 ng CryIAc protein per gram of rice. These results suggest that the lateral flow strip assay for GM cotton can be used to detect CryIAc protein expressed in GM rice.

Bacillus thuringiensis Toxins↗

PubMed2006

[Laboratory-performance study of quantitative PCR methods to analyze an approved genetically modified maize (Mon810 Line)].

A laboratory-performance study was carried out to investigate factors affecting the reliability of the quantitative PCR method to analyze an approved genetically modified (GM) maize (Mon810 line). Test maize powdered samples were prepared as blind samples containing a high (assigned value; 5.45%) or low (assigned value; 0.35%) concentration of the Mon810 line. After confirmation of their homogeneity, they were provided to 27 laboratories participating in the collaborative study. The data were collected from all laboratories and statistically analyzed. Two laboratories, which used a Roche LightCycler (LC), reported significantly high test values. A further examination showed that the LC method is greatly affected by the equipment itself or PCR reagents, resulting in poor repeatability. On the other hand, some laboratories, which used ABI quantitative PCR equipment, reported erroneous test values. In these laboratories, the errors appeared to have been due to inadequate quality and/or yield of DNA. To identify factors affecting the test values, analysis of the measured values for the taxon-specific gene will be useful. Furthermore, the modified silica-gel membrane DNA extraction method made it possible to extract the required amounts of DNA more easily and in a shorter time than before.

DNA, Plant↗

PubMed2005

[Laboratory performance study of the quantitative detection method for genetically modified soybeans (roundup ready soybeans 40-3-2)].

To investigate important factors affecting the analytical results, a laboratory-performance study was attempted for the Japanese official methods to detect genetically modified (GM) soybeans (40-3-2). Test samples containing 0, 1 and 5% GM soya powder in non-GM soya powder was prepared. A set of 3 test samples was sent to the participating laboratories along with the protocol. The data were collected from all laboratories and statistically analyzed. In the real-time PCR detection method, the average values of the GM 1% and 5% samples were both much lower than the spiked value because the laboratories using a silica-membrane DNA extraction method underestimated the GM value. On the other hand, the laboratories using other extraction methods, such as the CTAB method obtained values close to the spiked value. These results suggest that use of the silica-membrane DNA extraction method may result in underestimation of the GM content in the real-time PCR method. In the ELISA method, the average value of 5% spiked samples appears to be slightly higher than the fortified value. But, overall, it was considered that reported values were close to the spiked level.

DNA, Plant↗