Detection of genetically modified coho salmon using polymerase chain reaction (PCR) amplification

Identification of Fish Species and Targeted Genetic Modifications Based on DNA Analysis: State of the Art

Food adulteration is one of the most serious problems regarding food safety and quality worldwide. Besides misleading consumers, it poses a considerable health risk associated with the potential non-labeled allergen content. Fish and fish products are one of the most expensive and widely traded commodities, which predisposes them to being adulterated. Among all fraud types, replacing high-quality or rare fish with a less valuable species predominates. Because fish differ in their allergen content, specifically the main one, parvalbumin, their replacement can endanger consumers. This underlines the need for reliable, robust control systems for fish species identification. Various methods may be used for the aforementioned purpose. DNA-based methods are favored due to the characteristics of the target molecule, DNA, which is heat resistant, and the fact that through its sequencing, several other traits, including the recognition of genetic modifications, can be determined. Thus, they are considered to be powerful tools for identifying cases of food fraud. In this review, the major DNA-based methods applicable for fish meat and product authentication and their commercial applications are discussed, the possibilities of detecting genetic modifications in fish are evaluated, and future trends are highlighted, emphasizing the need for comprehensive and regularly updated online database resources.

Novel real-time PCR method based on growth hormone gene for identification of Salmonidae ingredient in food

To avoid fraudulent substitutions in fish markets, the proper methods are needed to test the authenticity of the ingredients. As a preferable methodology, a quantitative real-time polymerase chain reaction (qPCR) method was used in this study to identify species from the Salmonidae family based on the salmon growth hormone gene. Fish samples of six genera from the Salmonidae family were tested to identify the specificity, sensitivity, and applicability of the established method. Results showed that the method was highly specific for salmonid detection. Ct values were obtained only from 31 Salmonidae fish species samples. The relative and absolute limits of detection were 0.01% and 25 pg of genomic DNA, respectively, which could meet with the requirements of routine detections. To test the applicability of the method, the content of salmonid ingredients in 16 commercial food products was quantified from standard curves constructed from DNA of two Salmonidae species. The results revealed that the salmonid ingredient was detected in 12 samples, indicating that 25% of the labels are inauthentic. These results demonstrate that the developed qPCR method is suitable for identification of Salmonidae ingredients.

Calcium carbonate phosphate binding ion exchange filtration and accelerated denitrification improve public health standards and combat eutrophication in aquatic ecosystems

Cultural eutrophication, the process by which a lake becomes rich in dissolved nutrients as a result of point and nonpoint pollutant sources, is a major cause of the loss of natural lake ecosystems throughout the world. The process occurs naturally in all lakes, but phosphate-rich nutrient runoff from sources such as storm drains and agricultural runoff is a major cause of excess phosphate-induced eutrophication. Especially in Madrona Marsh, one of the last remaining vernal marshes in the greater Los Angeles area, California, cultural eutrophication has become a major problem. In this study, calcium carbonate was found to be an excellent phosphate binder, reducing up to 70% of the phosphates in a given sample of water, and it posed relatively negligent ecological repercussions. This study involved the testing of this principle in both the laboratory and the real ecosystem. A calcium carbonate lacing procedure was first carried out to determine its efficacy in Madrona Marsh. Through this, ammonia was found to interfere with the solubility of calcium carbonate and therefore to be a hindrance to the reduction of phosphate. Therefore, various approaches for reduction of ammonia were tested, including aeration, use of fiber growth media, and plants, mainly Caulerpa verticellata, chosen for it hardiness, primarily in an attempt to increase population of Nitrobacter and Nitrosomonas. All were successful in moderately reducing ammonia levels. In addition, soil sampling, sediment analysis, microscopic plant analysis, microorganism and macroinvertebrate identification, and rate law formulations were conducted. The effect of phosphate and ammonia reduction on the populations of enterobacteria was also an important focus of this experiment. Varying concentrations of phosphate, ammonia, and calcium carbonate in conjunction with phosphate were tested in Madrona Marsh to determine their effects on the populations of enteropathogens on nonspecific blood agar, MacConkey agar, and Hektoen agar. Initial analyses suggest a strong correlation between phosphate concentrations and bacterial populations; a 66% decrease in phosphate resulted in a 35% reduction in bacterial populations and a 45% reduction in enteropathogenic populations. Likewise, a strong correlation was shown between calcium carbonate concentrations and bacterial reduction greater than that which can be attributed to the phosphate reduction alone. This was followed by the construction of various phosphate binding calcium carbonate filters, which used the ion exchange principle, including a spring loading filter, PVC pipe filter, and a galvanized filter. All were tested with the aid of Stoke's law formulation. The experiment was extremely successful in designing a working phosphate-binding and ammonia-reducing filter, and a large-scale agitator-clarifier filter system is currently being planned for construction in Madrona Marsh; this filter will reduce phosphate and ammonia levels substantially in the following years, bringing ecological, economical, and health-related improvements to the overall ecosystem and habitat.

PCR-RFLP using a SNP on the mitochondrial Lsu-rDNA as an easy method to differentiate Tuber melanosporum (Perigord truffle) and other truffle species in cans

Canned truffle products labeled Tuber melanosporum, the famous Perigord truffle, may contain other less tasty and cheaper truffle species. To protect consumers from fraud, a PCR DNA-based method was used to unequivocally identify the nature of the product. Several rapid and simple cell lysis procedures, used in conjunction with a commercially available DNA purification kit, were evaluated for their effectiveness in recovering DNA from canned truffle. In parallel, a marker for T. melanosporum was tested on the mitochondrial rDNA. These two techniques were then combined to differentiate T. melanosporum from other truffle species like T. aestivum, T. brumale or T. indicum up to the legal threshold in canned products. These findings not only allow a comparison of the effectiveness of the different DNA extraction methods but also provide a preliminary indication of the specificity and sensitivity of the detection with the mitochondrial marker that might be attainable for truffle species in a quantitative PCR-based analysis method.