Development of DNA Based Technologies for Detection of Genetically Modified Organisms
Genetically modified organisms (GMOs) can be defined as organisms in which the genetic material (DNA) has been altered in a way that does not occur naturally by mating, pollination or natural recombination, i.e. by being genetically modified (GM) or by recombinant DNA technology. With the introdu...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2006
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| Online Access: | http://psasir.upm.edu.my/id/eprint/159/2/549009_fst_2006_1_abstrak_je__dh_pdf_.pdf http://psasir.upm.edu.my/id/eprint/159/ |
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| Summary: | Genetically modified organisms (GMOs) can be defined as organisms in which the
genetic material (DNA) has been altered in a way that does not occur naturally by
mating, pollination or natural recombination, i.e. by being genetically modified (GM)
or by recombinant DNA technology. With the introduction of foods derived from
genetically modified organisms in the market, there has been an increasing need for
appropriate analytical methods to comply with the strict regulations in the European
Union (EU) and other regions.
Raw, processed food and animal feed were the three main category of food used in
this study. In addition, the matrices of food tested comprise solid, semi-solid and
liquid. Thus, different DNA isolation techniques were used in this study to ensure the
quality and purity of the extracted DNA. The DNA extraction techniques used in this
study were based on the silica column binding and magnetic bead entrapment
technology.The polymerase chain reaction (PCR) allows the millionfold amplification of a target
DNA fragment in a highly sensitive and specific manner. Single specific PCR with
the published and designed primers were generated. Combination of the published and
new primers in PCR contributes to the development of rapid detection in GMO
analyses.
In real-time PCR technology, the amplification of the DNA sequence can be
monitored during the whole reaction by indirect monitoring of the product formation.
Real-time detection strategies rely on continuous measurements of the increments in
the fluorescence generated during the PCR. The chemistries for the real-time PCR
used in this study include SYBR Green I, hybridization probes (Taqman) and
AmplifluorTM universal system. The SYBR Green I and the hybridization probes
system used in this study was successfully optimized to detect delta endotoxin gene
from Bacillus thuringiensis, (CryIA(b)), gene for 5’enol-pyruvylshikimate-3-
phosphate synthase (EPSPS), species specific regions of the soybean lectin gene and
the maize zein gene. On the other hand, the AmplifluorTM universal system was
successfully optimized for the detection of the soybean lectin gene, Cauliflower
Mosaic virus 35S promoter gene and the Roundup Ready soya specific gene.
Dot blot assay provides an alternative detection method in GMO detection. Two
biotinylated probes were successfully generated for the detection of transgenic food
namely the detection of the 5’enol-pyruvylshikimate-3-phosphate synthase (EPSPS)
gene and the Cauliflower Mosaic virus 35S promoter gene fragments. In addition, the
membrane-based technique described in this study involves the use of chemiluminescent detection. Although this nonradioactive DNA probes is lower
sensitivity than PCR, it is easier to process for large numbers of samples at once and
inexpensive.
Random amplified polymorphic DNA (RAPD) analysis used in this study was able to
distinguish between commercially obtained genetically modified materials with
normal food. Random primer OPAR 4 and OPAR 13 were found to discriminate the
samples from standards used. The RAPD analysis introduced in this study could be
used in pre-GMO food screening and genetic relatedness investigation. Besides that,
the combined banding profile analysis of both OPAR4 and OPAR13 revealed better
clustering of the samples tested. RAPD patterns are always species-specific and some
primers produce highly polymorphic patterns within a species.
Biospecific interaction analysis (BIA) via Surface Plasmon Resonance (SPR) for the
detection of the lectin, CaMV 35S promoter, Nos terminator and Roundup Ready
gene introduced in this study is an appropriate method for GMO detection since the
techniques is label free, no toxic compounds are required, easy, rapid, specific and
automatable. Since light does not penetrate the sample, interactions can be followed in
colored, turbid or opaque samples. Thus, BIA via SPR is suitable for the detection of
GMO especially in processed food. In this study, attempts were successfully
conducted in detection of asymmetry PCR amplicons and raw DNA extracts of
selected GMO products.
As conclusion, all the DNA based method described in this study demonstrated fast,
accurate and specific approach. Besides that, techniques such as RAPD introduced in
this study can used as an investigation tools in the study of genetic relatedness between GMO and non-GMO samples. On the other hand, dot blot analysis described
in this study offers an alternative inexpensive approach in preliminary detection of
GMOs. Likewise, a combination of several DNA based detection method such as
Real-time PCR (SYBR Green I, hybridization probes (Taqman) and AmplifluorTM
universal system) and SPR biosensor will ensure reliable and reproducible results. |
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