High-Throughput Proteomics: A New Tool for Quality and Safety in Fishery Products

Proteomics for understanding pathogenesis, immune modulation and host pathogen interactions in aquaculture

Proteomic analyses techniques are considered strong tools for identifying and quantifying the protein contents in different organisms, organs and secretions. In fish biotechnology, the proteomic analyses have been used for wide range of applications such as identification of immune related proteins during infections and stresses. The proteomic approach has a significant role in understanding pathogen surviving strategies, host defence responses and subsequently, the fish pathogen interactions. Proteomic analyses were employed to highlight the virulence related proteins secreted by the pathogens to invade the fish host's defence barriers and to monitor the kinetics of protein contents of different fish organs in response to infections. The immune related proteins of fish and the virulence related proteins of pathogens are up or down regulated according to their functions in defence or pathogenesis. Therefore, the proteomic analyses are useful in understanding the virulence mechanisms of microorganisms and the fish pathogen interactions thereby supporting the development of new effective therapies. In this review, we focus and summarise the recent proteomic profiling studies exploring pathogen virulence activities and fish immune responses to stressors and infections.

Top-Down Proteomics and Farm Animal and Aquatic Sciences

Proteomics is a field of growing importance in animal and aquatic sciences. Similar to other proteomic approaches, top-down proteomics is slowly making its way within the vast array of proteomic approaches that researchers have access to. This opinion and mini-review article is dedicated to top-down proteomics and how its use can be of importance to animal and aquatic sciences. Herein, we include an overview of the principles of top-down proteomics and how it differs regarding other more commonly used proteomic methods, especially bottom-up proteomics. In addition, we provide relevant sections on how the approach was or can be used as a research tool and conclude with our opinions of future use in animal and aquatic sciences.

Authentication of Closely Related Fish and Derived Fish Products Using Tandem Mass Spectrometry and Spectral Library Matching

Proteomics methodology has seen increased application in food authentication, including tandem mass spectrometry of targeted species-specific peptides in raw, processed, or mixed food products. We have previously described an alternative principle that uses untargeted data acquisition and spectral library matching, essentially spectral counting, to compare and identify samples without the need for genomic sequence information in food species populations. Here, we present an interlaboratory comparison demonstrating how a method based on this principle performs in a realistic context. We also increasingly challenge the method by using data from different types of mass spectrometers, by trying to distinguish closely related and commercially important flatfish, and by analyzing heavily contaminated samples. The method was found to be robust in different laboratories, and 94-97% of the analyzed samples were correctly identified, including all processed and contaminated samples.

Proteomics for the authentication of fish species

Assessment of seafood authenticity and origin, mainly in the case of processed products (fillets, sticks, baby food) represents the crucial point to prevent fraudulent deceptions thus guaranteeing market transparency and consumers health. The most dangerous practice that jeopardies fish safety is intentional or unintentional mislabeling, originating from the substitution of valuable fish species with inferior ones. Conventional analytical methods for fish authentication are becoming inadequate to comply with the strict regulations issued by the European Union and with the increase of mislabeling due to the introduction on the market of new fish species and market globalization. This evidence prompts the development of high-throughput approaches suitable to identify unambiguous biomarkers of authenticity and screen a large number of samples with minimal time consumption. Proteomics provides suitable and powerful tools to investigate main aspects of food quality and safety and has given an important contribution in the field of biomarkers discovery applied to food authentication. This report describes the most relevant methods developed to assess fish identity and offers a perspective on their potential in the evaluation of fish quality and safety thus depicting the key role of proteomics in the authentication of fish species and processed products.

BIOLOGICAL SIGNIFICANCE

The assessment of fishery products authenticity is a main issue in the control quality process as deceptive practices could imply severe health risks. Proteomics based methods could significantly contribute to detect falsification and frauds, thus becoming a reliable operative first-line testing resource in food authentication.

The Use of Peptide Markers of Carp and Herring Allergens as an Example of Detection of Sequenced and Non-Sequenced Proteins

The objective of this study is to identify fish protein markers for detecting multiple species based on a comparative proteomic approach that relies on fragments with identical sequences. The possibilities and challenges of the use of peptides obtained from carp (Cyprinus carpio) and herring (Clupea harengus) proteins are discussed. A bioinformatic analysis was followed by an LC-MS/MS experiment to identify markers predicting the presence of fish allergenic proteins. Selected myosin peptides were found in carp protein hydrolysates with known sequences and in herring protein hydrolysates with unknown sequences. The results obtained for carp and herring proteins myosin and parvalbumin indicate that proteins with unknown sequences can be identified by peptide markers. Such markers can be designed by disregarding the principle that peptides should be unique (present in one sequence). The challenge is to determine a group of proteins that can be detected by peptide identification.

Common Amino Acid Subsequences in a Universal Proteome--Relevance for Food Science

A common subsequence is a fragment of the amino acid chain that occurs in more than one protein. Common subsequences may be an object of interest for food scientists as biologically active peptides, epitopes, and/or protein markers that are used in comparative proteomics. An individual bioactive fragment, in particular the shortest fragment containing two or three amino acid residues, may occur in many protein sequences. An individual linear epitope may also be present in multiple sequences of precursor proteins. Although recent recommendations for prediction of allergenicity and cross-reactivity include not only sequence identity, but also similarities in secondary and tertiary structures surrounding the common fragment, local sequence identity may be used to screen protein sequence databases for potential allergens in silico. The main weakness of the screening process is that it overlooks allergens and cross-reactivity cases without identical fragments corresponding to linear epitopes. A single peptide may also serve as a marker of a group of allergens that belong to the same family and, possibly, reveal cross-reactivity. This review article discusses the benefits for food scientists that follow from the common subsequences concept.