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chromatography, and high-performance liquid chromatography combined with various detection
methods such as NMR,Fouriertransform-impaired spectroscopy, mass spectroscopy, and lame
ionizationdetector(Celecetal.2005).
New methods and techniques have been developed within the framework of the European
Research Project “Development of Methods to Identify Foods Produced by Means of Genetic
Engineering”(ProjectNo.SMT4-CT96-2072).Inthescopeofthisproject,DNAextractionmeth-
odshavebeencompared(Zimmermannetal.1998a),newprimersandprobeshavebeendeined,
ringtestswithtomato,processedmaize,andsoyaarebeingperformed,andadatabaserecording
detailedinformationaboutGMO-containingfoodonthemarket,sequences,primers,anddetection
methodshasbeensetup(Schreiber1997).
12.4.1 Methods for Genome analysis
12.4.1.1 Restriction Fragment Length Polymorphism
RFLP is a technique in which organisms may be differentiated by the analysis of patterns
derivedfromthecleavageoftheirDNA.Organismscandifferinthedistancebetweensitesofthe
cleavage of a particular restriction endonuclease, and the length of the fragments produced will
differwhentheDNAisdigestedwitharestrictionenzyme.Therestrictionfragmentsareseparated
accordingtolengthbyagarosegelelectrophoresis.Theresultinggelmayfurtherbeanalyzedby
Southernblottingusingspeciicprobes.Thesimilarityofthepatternsgeneratedcanbeusedtodif-
ferentiateevenstrainsofthesameorganism.RFLPhasbeenrecentlycombinedwithmicrosynteny
analysiscomparingtomatotothe
Arabidopsis
genome,andnewmicrosyntenicexpressedsequence
tagmarkerswererapidlyidentiied(Argyropoulosetal.2008;Ohetal.2002;Figure12.1).
Genomic DNA
Restriction
site
Probed
region
Gel electrophoresis and Southern blotting
Blotted
DNA
Direction of
DNA migration
and size
separation
Figure 12.1
RFLPs are molecular markers used to create genetic maps of chromosomes. Combinations of
enzymes and probes with digested DNA produce different proiles of DNA fragments, unique
for each organism. The direction of DNA migration and size separation is shown by the arrow.
Gel electrophoresis and Southern blotting show blotted DNA. (Adapted from Varzakas, T. et al.,
in
Tomatoes and Tomato Products, Nutritional, Medicinal and Therapeutic Properties
, edited
by V.R. Preedy and R.R. Watson, pp. 515-536, Science Publishers, Enield, NH, 2008. With
permission.)
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