Concern over food authenticity has increased as a result of an increase in the consumption of processed foods containing meat or animal products. This raises a number of issues where the presence of pork in such foods is considered unacceptable in most Muslim and Jewish communities around the world. It also applied to the prohibition of beef consumption among Hindus. In order to ensure the absence of unwished meat products or mixing of meats from different sources in processed foods, a specific and sensitive test is essential. For this purpose we developed a molecular test based on DNA amplification by polymerase chain reaction (PCR) of the cytochrome b gene followed by reverse line blot analysis (RLB). Using this method many samples may be treated simultaneously and meat origins can easily be detected from processed foods or foods containing mixed meat sources; also, added pork components such as fat may be identified by this methodology. The PCR/RLB method is considered to be a sensitive and specific technique; it can detect one nucleotide change within the PCR-amplified DNA segment.
(Al-Quds University - Deanship of Scientific Research, 2021-02-20) Abbasi, Ibrahim; Halaseh, Lamia; Darwish, Hisham M.; Matouk, Imad
Stored grains are subjected to infestations with more than 60 species of insects, that responsible for millions of dollars loss and cause several health problems including allergies and gastrointestinal disorders. Traditional detection techniques are laborious, expensive and not sensitive to detect insect contamination at the egg and larvae stages. Therefore, alternative methods are needed for rapid and sensitive detection. One obvious approach is to develop a molecular approach utilizing genetic information of the potential insect species that infest grains for amplification of specific target gene fragment utilizing polymerase chain reaction [PCR]. In the present study, a number of known infested grain samples were used in standardizing a method to isolate larvae and adult insects that were based on centrifugation washing method and a filtration washing method. The isolated insects were subjected to DNA extraction and PCR amplification of defined regions of cytochrome oxidase I (COI) gene followed by sequencing to identify the different pest species. For PCR amplification new primers were designed and for this purpose the obtained COI sequences from different insects were aligned to design two sets of primers (named: COI-PCR4 and COI-PCR5) specific for the indicated insect mitochondrial COI gene. The designed primers were tested for their specificity and sensitivity. The suitability of PCR primers and DNA extraction methods were evaluated on eleven samples of commercial grains utilizing each primer set with the two extraction methods.
(BMC, 2017-08-01) Abbasi, Ibrahim; Webster, Bonnie L.; King, Charles H.; Rollinson, David; Hamburger, Joseph
Background: Schistosoma haematobium is the causative agent of human urogenital schistosomiasis affecting ~112
million people in Africa and the Middle East. The parasite is transmitted by snails of the genus Bulinus, which also
transmit other closely related human and animal schistosomes. The accurate discrimination of S. haematobium from
species infecting animals will aid effective control and elimination programs. Previously we have shown the utility
of different repetitive nuclear DNA sequences (DraI, sh73bp, and sh77bp) for the identification of S. haematobiumgroup
species and inter-repeat sequences for discriminating S. haematobium from S. bovis.
Results: In this current study we clarify the structural arrangement and association between the three repetitive
sequences (DraI, sh73bp, and sh77bp) in both S. haematobium and S. bovis, with a unique repeat linker being found
in S. haematobium (Sh64bp repeat linker) and in S. bovis (Sb30bp repeat linker). Sequence data showed that the 3′-
end of the repeat linker was connected to the DraI repetitive sequence array, and at the 5′-end of the repeat linker
sh73bp and sh77bp were arranged in an alternating manner. Species-specific oligonucleotides were designed targeting
the species-specific repeat linkers and used in a reverse line blot (RLB) hybridization assay enabling differentiation
between S. haematobium and S. bovis. The assay was used to discriminate natural infections in wild caught
Bulinus globosus.
Conclusion: This research enabled the characterisation of species-specific DNA regions that enabled the design
of species-specific oligonucleotides that can be used to rapidly differentiate between S. haematobium and S. bovis and
also have the potential to aid the detection of natural hybridization between these two species.