qpcr (3)


Although there are thirteen varieties of ginseng, only two are commercialised in herbal products - Asian ginseng (Panax ginseng) and American ginseng (Panax quinquefolius). Ginseng root is a popular medicinal plant with a global estimated value of USD 2.1 billion. The two varieties are highly valued in their respective markets, and intentional mixing often takes place for economic reasons as does potential adulteration with other plants. Therefore, this study developed a DNA assay to identify the two species and distinguish them from potential adulterants. Preparation of the milled ginseng root degrades the DNA, which makes barcoding or sequencing not practical assays to identify the two types of ginseng. Therefore, specific hydrolysis probe-qPCR for the two varieties of ginseng was developed, and validated on a portable qPCR instrument using 9 authentic samples of P. ginseng and 10 authentic samples of P. quinquefolius, with 19 authentic samples of other potential adulterating plants. The assay was found to be 100% specific for each variety of ginseng with no cross reaction with the 19 other plants. The assay was then tested with 42 commercial herbal products of P. ginseng and 40 commercial products of P. quinquefolius purchased in China, Canada and the USA, which found that 2 of the P. ginseng products were incorrectly labelled and were P. quinquefolius. 

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Following the previous LGC e-seminars on quantitative PCR assay design and PCR assay optimisation, this e-seminar, entitled “An introduction to quantitative PCR assay validation”, will introduce the viewer to the topic of qPCR assay validation and provide best practice guidance on how to undertake the process. The information presented will equip viewers with the necessary knowledge and skills to ensure that methods are validated and fit for purpose. Key stages in the validation process are indicated, routinely employed evaluation parameters described and critical performance criteria highlighted. Links to useful resources, additional guidance and references are also provided.

Those who should consider viewing this e-seminar include individuals currently working within the foods molecular testing area, particularly representatives from UK Official Control Laboratories, industry and members of organisations associated with the UK official control network.

The production of this e-seminar was funded by Defra, FSA, FSS and BEIS under the Joint Knowledge Transfer Framework for Food Standards and Food Safety Analysis.

This e-seminar can be be viewed on LGC's YouTube channel at  https://youtu.be/grf4tZQOArM

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This paper describes a method based on combining a streamlined DNA extraction method and a SYBR Green quantitative polymerase chain reaction (SyG-qPCR) assay to generate a ready-to-use kit for rapid detection of pork admixtures in processed meat products. The method utilises a rapid and efficient DNA extraction from samples and PCR analysis, which were completed in 10 minutes. The qPCR assay utilised repetitive LINE-1 elements specific to the genome of Sus scrofa domesticus (pig) as a target and incorporated internal controls. The method was validated using 121 processed meat products,  and  amplification was consistently detected only in samples containing pork. 

 1337352593?profile=RESIZE_710x                                    Read the abstract here

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