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DNA-BASED DETECTION DNA-BASED DETECTION METHODMETHODOF PLANT-DERIVED ALLERGENS OF PLANT-DERIVED ALLERGENS IN FOODSTUFFSIN FOODSTUFFSMaster's Thesis
Jekaterina LossevaSupervisors: Olga Bragina, PhD; TUT
Svetlana Sergejeva, MD, PhD; TUIT
Lilian Järvekülg, PhD; TUT
11.06.2014
The planThe planIntroduction
◦Food hypersensitivity◦Food allergy◦Detection methods
Aims of the studyMaterials and methodsResults
Food allergyFood allergyPrevalence
◦2% - adults◦18% - children
Treatment◦Avoidance of the causative food
Potentially allergenic foods gluten-containing cereals, crustaceans,
eggs, fish, nuts, soybean, milk, celery, mustard, sesame, sulphites, lupine and molluscs.
Detection of allergensDetection of allergensProtein-based methods
◦Immunoblotting◦enzyme-linked immunosorbent assay
(ELISA)DNA-based methods
◦PCR◦PCR-ELISA◦Real-time PCR
Aims of this studyAims of this studydetermine the most sufficient plant
DNA extraction methods from different foodstuffs
create DNA library of selected plants
evaluate specie-specificity of designed in the frame of Allergofood project primers
examine the sensitivity of species-specific primers.
Materials and methodsMaterials and methodsDNA extraction methods
◦Basic guanidine/chloroform◦Basic phenol/chloroform◦Cetyltrimethylammonium bromide
(CTAB)◦CTAB Precipitation◦2xCTAB◦DNeasy Plant Mini Kit◦Some modifications to the Kit
Materials and methodsMaterials and methodsPCR amplification
Universal primers
Species-specific primers (Touchdown PCR)
Step Temperature Duration Repeats
Initial polymerase activation 95°C 15 min 1
Denaturation 95°C 30 sec
35Annealing 50°C 30 sec
Elongation 72°C 30 sec
Final elongation 72°C 5 min 1
Step Temperature Duration Repeats
Initial polymerase activation 95°C 15 min 1
Denaturation 95°C 30 sec
20Annealing 65°C to 54°C 30 sec
Elongation 72°C 30 sec
Denaturation 95°C 30 sec
20Annealing 54°C 30 sec
Elongation 72°C 30 sec
Final elongation 72°C 5 min 1
DNA extraction methodsDNA extraction methods A – basic
phenol/chloroform C – CTAB
B – basic guanidine/chloroform
D – CTAB precipitation
Lanes 2 to 9 represent mustard, cacao, Brazil nut, pecan, chocolate with plum, chocolate with cherry, sesame and radish
Species-specific primersSpecies-specific primersMacadamiaHazelnut 0,025 ngPeanutPistachio 0,025 ngAlmond 0,0025 ngWalnutCashew 0,25 ngBrazil nut 0,0025
ngPecan
Soya 0,025 ngMustard orientalMustard whiteSesame 0,025 ngLupine 0,0025 ngWheat 0,0025 ngRyeBarley 0,0025 ngOat 0,0025 ngCelery
SummarySummaryDNA extraction:
◦CTAB precipitation method for DNA extraction from foodstuffs
◦DNeasy Plant Mini Kit for DNA extraction from leaf
◦The same Kit with modification for DNA extraction from nuts
Touchdown PCR method as highly sensitive and specific method