Spectra Of Peptides Research Articles

Determination of Local Structure of 13C Selectively Labeled 47-mer Peptides as a Model for Gly-Rich Region of Nephila clavipes Dragline Silk Using a Combination of 13C Solid-State NMR and MD Simulation

For the first time, we elucidate the complex structure of the Gly-rich regions in Nephila clavipes dragline silk through synergistic experimental and theoretical studies. First, the 13C selectively labeled 47-mer peptides selected from the glycine (Gly)-rich region of N. clavipes dragline silk were synthesized. The 13C CP/MAS NMR spectra were analyzed to determine the fractions of the conformations of individual Gly and Ala residues through 13C conformation-dependent chemical shifts and peak deconvolution. By comparing the 13C solid-state NMR spectra of several simple model peptides, the presence of 31 helix in the 47-mer peptides was disproved, and the (Ala)6 regions were shown to form β-sheet structure in the staggered arrangement. Although the fraction of β-sheet components tended to increase and the fraction of random coil component decrease toward both chain ends, significant change in the fractions was observed depending on the amino acid position. These results were successfully rationalized throug...

Development of a Trypanosoma cruzi strain typing assay using MS2 peptide spectral libraries (Tc-STAMS2).

BackgroundChagas disease also known as American trypanosomiasis is caused by the protozoan Trypanosoma cruzi. Over the last 30 years, Chagas disease has expanded from a neglected parasitic infection of the rural population to an urbanized chronic disease, becoming a potentially emergent global health problem. T. cruzi strains were assigned to seven genetic groups (TcI-TcVI and TcBat), named discrete typing units (DTUs), which represent a set of isolates that differ in virulence, pathogenicity and immunological features. Indeed, diverse clinical manifestations (from asymptomatic to highly severe disease) have been attempted to be related to T.cruzi genetic variability. Due to that, several DTU typing methods have been introduced. Each method has its own advantages and drawbacks such as high complexity and analysis time and all of them are based on genetic signatures. Recently, a novel method discriminated bacterial strains using a peptide identification-free, genome sequence-independent shotgun proteomics workflow. Here, we aimed to develop a Trypanosoma cruzi Strain Typing Assay using MS/MS peptide spectral libraries, named Tc-STAMS2.Methods/Principal findingsThe Tc-STAMS2 method uses shotgun proteomics combined with spectral library search to assign and discriminate T. cruzi strains independently on the genome knowledge. The method is based on the construction of a library of MS/MS peptide spectra built using genotyped T. cruzi reference strains. For identification, the MS/MS peptide spectra of unknown T. cruzi cells are identified using the spectral matching algorithm SpectraST. The Tc-STAMS2 method allowed correct identification of all DTUs with high confidence. The method was robust towards different sample preparations, length of chromatographic gradients and fragmentation techniques. Moreover, a pilot inter-laboratory study showed the applicability to different MS platforms.Conclusions and significanceThis is the first study that develops a MS-based platform for T. cruzi strain typing. Indeed, the Tc-STAMS2 method allows T. cruzi strain typing using MS/MS spectra as discriminatory features and allows the differentiation of TcI-TcVI DTUs. Similar to genomic-based strategies, the Tc-STAMS2 method allows identification of strains within DTUs. Its robustness towards different experimental and biological variables makes it a valuable complementary strategy to the current T. cruzi genotyping assays. Moreover, this method can be used to identify DTU-specific features correlated with the strain phenotype.

Derivation and characterization of a California grunion (Leuresthes tenuis) embryonic cell line

An immortalized cell line was established from newly hatched embryos of the California grunion (Leuresthes tenuis), a silverside fish, to generate a tool for mechanistic studies explaining the effect of environmental stressors on proteome dynamics. In this oviparous species, fertilization occurs terrestrially, and embryos develop in beach sand until environmentally-cued hatching. Grunion eggs and embryos are subject to multiple environmental stressors including changes in salinity, desiccation, heat, and pollutant runoff, which can reduce fertilization, embryonic development, and hatching success [1–3]. Cell lines derived from grunion embryo primary tissue explants thus provide a valuable tool for high-throughput reverse genetics (e.g., high-throughput enhancer trap assays, knock-out studies, and targeted mutagenesis) and proteomics approaches to enable mechanistic explanations of cellular and molecular responses to environmental stressors. Two parallel cell lines were derived from the same whole grunion embryonic tissue and have been maintained now over 10 passages at a 1:6 splitting ratio. Both cell lines display an epithelial-like phenotype (cuboidal, monolayer, optically dense). A time course experiment was conducted to document effects of cell immortalization on the proteome of both cell lines sampled at each passage. Data-dependent mass spectrometry acquisition of peptide spectra and de novo sequencing were used to annotate spectral libraries with protein identification information. Spectral libraries were then used to construct and validate target sets that enable quantitation of proteome dynamics with data-independent acquisition (cDIA) and Skyline. Passage-dependent changes in proteome dynamics were identified by cDIA target set quantitation with Skyline and correspond to morphological changes in cell types over time. Support or Funding Information Supported by NSF Grant IOS-1355098. Fibroblast and epithelial-like cells derived from grunion after the first passage (A) and third passage (B). This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Proteomic analysis of corneal endothelial cell-descemet membrane tissues reveals influence of insulin dependence and disease severity in type 2 diabetes mellitus.

The objective of this study was to characterize the proteome of the corneal endothelial cell layer and its basement membrane (Descemet membrane) in humans with various severities of type II diabetes mellitus compared to controls, and identify differentially expressed proteins across a range of diabetic disease severities that may influence corneal endothelial cell health. Endothelium-Descemet membrane complex tissues were peeled from transplant suitable donor corneas. Protein fractions were isolated from each sample and subjected to multidimensional liquid chromatography and tandem mass spectrometry. Peptide spectra were matched to the human proteome, assigned gene ontology, and grouped into protein signaling pathways unique to each of the disease states. We identified an average of 12,472 unique proteins in each of the endothelium-Descemet membrane complex tissue samples. There were 2,409 differentially expressed protein isoforms that included previously known risk factors for type II diabetes mellitus related to metabolic processes, oxidative stress, and inflammation. Gene ontology analysis demonstrated that diabetes progression has many protein footprints related to metabolic processes, binding, and catalysis. The most represented pathways involved in diabetes progression included mitochondrial dysfunction, cell-cell junction structure, and protein synthesis regulation. This proteomic dataset identifies novel corneal endothelial cell and Descemet membrane protein expression in various stages of diabetic disease. These findings give insight into the mechanisms involved in diabetes progression relevant to the corneal endothelium and its basement membrane, prioritize new pathways for therapeutic targeting, and provide insight into potential biomarkers for determining the health of this tissue.

Picky: a simple online PRM and SRM method designer for targeted proteomics.

Targeted proteomic approaches like selected reaction monitoring (SRM) and parallel reaction monitoring (PRM) are increasingly popular because they enable sensitive and rapid analysis of a preselected set of proteins. However, developing targeted assays is tedious and requires the selection, synthesis and mass spectrometric analysis of candidate peptides before the actual samples can be analyzed. The SRMatlas and ProteomeTools projects recently published fragmentation spectra of synthetic peptides covering the entire human proteome. These datasets provide very valuable resources. However, extracting the relevant data for selected proteins of interest is not straightforward. For example, developing scheduled acquisition methods (i.e. analyzing specific peptides in defined elution time windows) is complicated and requires adjustments to specific chromatographic conditions employed. Here, we present Picky: a fast and easy to use online tool to design scheduled PRM/SRM assays (https://picky.mdc-berlin.de). Picky (i) automatically generates optimized and scheduled SRM/PRM assays for proteins of interest and (ii) provides means to validate the data via known fragmentation spectra of corresponding synthetic peptides.

Rapid and robust MALDI-TOF MS techniques for microbial identification: a brief overview of their diverse applications.

in mass spectrometry have enabled the investigation of various biological systems by directly analyzing diverse sets of biomolecules (i.e., proteins, lipids, and carbohydrates), thus making a significant impact on the life sciences field. Over the past decade, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been widely utilized as a rapid and reliable method for the identification of microorganisms. MALDI-TOF MS has come into widespread use despite its relatively low resolving power (full width at half maximum, FWHM: < 5,000) and its incompatibility with tandem MS analysis, features with which other high-resolution mass spectrometers are equipped. Microbial identification is achieved by searching databases containing mass spectra of peptides and proteins extracted from microorganisms of interest, using scoring algorithms to match analyzed spectra with reference spectra. In this paper, we give a brief overview of the diverse applications of rapid and robust MALDI-TOF MS-based techniques for microbial identification in a variety of fields, such as clinical diagnosis and environmental and food monitoring. We also describe the fundamental principles of MALDI-TOF MS. The general specifications of the two major MS-based microbial identification systems available in the global market (BioTyper® and VITEK® MS Plus) and the distribution of these instruments in Republic of Korea are also discussed. The current review provides an understanding of this emerging microbial identification and classification technology and will help bacteriologists and cell biologists take advantage of this powerful technique.

Elucidation of cross-species proteomic effects in human and hominin bone proteome identification through a bioinformatics experiment

BackgroundThe study of ancient protein sequences is increasingly focused on the analysis of older samples, including those of ancient hominins. The analysis of such ancient proteomes thereby potentially suffers from “cross-species proteomic effects”: the loss of peptide and protein identifications at increased evolutionary distances due to a larger number of protein sequence differences between the database sequence and the analyzed organism. Error-tolerant proteomic search algorithms should theoretically overcome this problem at both the peptide and protein level; however, this has not been demonstrated. If error-tolerant searches do not overcome the cross-species proteomic issue then there might be inherent biases in the identified proteomes. Here, a bioinformatics experiment is performed to test this using a set of modern human bone proteomes and three independent searches against sequence databases at increasing evolutionary distances: the human (0 Ma), chimpanzee (6-8 Ma) and orangutan (16-17 Ma) reference proteomes, respectively.ResultsIncorrectly suggested amino acid substitutions are absent when employing adequate filtering criteria for mutable Peptide Spectrum Matches (PSMs), but roughly half of the mutable PSMs were not recovered. As a result, peptide and protein identification rates are higher in error-tolerant mode compared to non-error-tolerant searches but did not recover protein identifications completely. Data indicates that peptide length and the number of mutations between the target and database sequences are the main factors influencing mutable PSM identification.ConclusionsThe error-tolerant results suggest that the cross-species proteomics problem is not overcome at increasing evolutionary distances, even at the protein level. Peptide and protein loss has the potential to significantly impact divergence dating and proteome comparisons when using ancient samples as there is a bias towards the identification of conserved sequences and proteins. Effects are minimized between moderately divergent proteomes, as indicated by almost complete recovery of informative positions in the search against the chimpanzee proteome (≈90%, 6-8 Ma). This provides a bioinformatic background to future phylogenetic and proteomic analysis of ancient hominin proteomes, including the future description of novel hominin amino acid sequences, but also has negative implications for the study of fast-evolving proteins in hominins, non-hominin animals, and ancient bacterial proteins in evolutionary contexts.

Integrated proteomics sample pretreatment method based onSCX/SAX mixed packing

An integrated technology for preparing proteomics samples was developed based on SCX/SAX mixed beads. Unlike previously reported SISPROT strategies, SCX/SAX mixed beads were used to replace SCX beads. A mixture of BSA and LYZ was chosen as the model protein to evaluate the protein retention behavior of the SCX/SAX beads at pH of 3, 7.4, and 12. The mass ratio of SCX/SAX was optimized using the BCA method. Further, the protein loss caused by pH replacement during digestion was systematically investigated by the SDS-PAGE method. The results indicated that at a pH of 7.4, the optimized mass ratio of SCX/SAX mixed beads was 1:1, and the loading capacity of SCX/SAX mixed beads with the mass ratio of 1:1 was 180 µg, which is almost twice that of SCX beads. Furthermore, pH replacement during digestion did not affect the protein retention behavior of SCX/SAX mixed beads. The improved SISPROT method was used for processing a limited quantity of colon cancer tumor samples. For comparison, the traditional SISPROT method based on SCX beads was used. The results indicated that the number of protein identification, unique peptides and peptide spectrum matching obtained from the two methods were comparable. These results confirmed the applicability of the method as a proteomics reactor. The method is expected to be a more generic sample preparation technology because it can be operated at physiological pH and exhibits significantly improved loading capacity and reduced sample loss compared with those of the traditional SISPROT method.

Determination of the enzyme destruction rational mode of biomass autolysate of lactic acid bacteria

It is shown that the degradation products of peptidoglycans of lactic acid bacteria cell walls that are related to the muramyl peptide series compounds are promising components of food ingredients and dietary supplements for the nutritional support of the population suffering from disorders of the immune system. The expediency of autolysis of lactic acid bacteria biomass to increase the enzymatic degradation efficiency of peptidoglycans of their cell walls has been proven. The accumulation of low molecular weight peptides in the enzymatic hydrolysis of biomass under rational parameters, which was not subjected to autolysis, is 0.260 mg/cm 3 , in the enzymatic hydrolysis of biomass that was subjected to autolysis is 0.569 mg/cm 3 . Rational regimes of enzymatic hydrolysis of the composition of lactic acid bacteria (enzyme concentration of 12.5 mg/cm 3 , substrate concentration of 70.0 mg/cm 3 , duration of enzymatic hydrolysis of 245.6 min) were determined using mathematical planning methods of multifactorial experiments, which made it possible to significantly optimize and improve the work efficiency. The affiliation of low molecular weight peptides obtained under the rational conditions of enzymatic hydrolysis to immunological compounds of the muramyl peptide series has been proven by gel chromatography and IR spectroscopy methods. It is determined that the molecular weight of the obtained low molecular weight peptides is in the range of 294 – 650 Da, which, in fact, corresponds to the molecular weight of muramyl dipeptide and glucosaminylmuramyl dipeptide. In the IR spectrum of low molecular weight peptides, the absorption bands are noted, which correspond to fluctuations of free amino groups, peptide bonds, which, in fact, occur in the structure of peptides, pyranose glucose forms that are part of muramic acid and N-acetylglucosamine of peptidoglycan, muramyl dipeptide and glucosaminylmuramyl dipeptide. Also, fluctuations of β-glycoside bonds, which binds the remains of muramic acid and N-acetylglucosamine in peptidoglycan and glucosaminylmuramyl dipeptide are marked in the IR spectrum of low molecular weight peptides

High-Accuracy Mass Spectrometry Based Screening Method for the Discovery of Cysteine Containing Peptides in Animal Venoms and Toxins.

Venom and toxin samples derived from animal origins are a rich source of bioactive peptides. A high proportion of bioactive peptides that have been identified in venom contain one or more disulfide bridges, which are thought to stabilize tertiary structure, and therefore influence the peptides' specificity and activity. In this chapter, we describe a label-free mass spectrometry-based screening workflow specifically to detect peptides that contain inter- and intramolecular disulfide bonds, followed by elucidation of their primary structure. This method is based on the determination of the normalized isotope shift (NIS) and the normalized mass defect (NMD) of peptides, two parameters which are heavily influenced by the presence of sulfur in a peptide, where cysteines are the main contributing residues. Using ant defensive secretions as an example, we describe the initial fractionation of the venom on strong cation exchange followed by nanoflow HPLC and mass spectrometry. High resolution zoom scan spectra of high-abundance peptides are acquired, allowing an accurate determination of both monoisotopic and average mass, which are essential for calculation of NMD and NIS. Candidate peptides exhibiting relative low NMD and high NIS values are selected for targeted de novo sequencing. By fine-tuning the collision energy for optimal fragmentation of each selected precursor ions, the full sequence of several novel inter- and intramolecular disulfide bond containing ant defensive peptides can be established.

Comparison of gel-aided sample preparation (GASP) and two in-solution digestion workflows for proteomic analysis using Saccharomyces cerevisiae lysate

Using Saccharomyces cerevisiae lysate, two in-solution trypsin digestions (chloroform-methanol-water precipitation and RapiGest) were compared to the recently reported gel-aided sample preparation (GASP) workflow. Our proteomic results showed that GASP afforded the highest number of overall protein identifications and peptide spectrum matches without systematic bias towards peptide or protein size.

Nonlocalized Searching of HCD Data for Fast and Sensitive Identification of ADP-Ribosylated Peptides.

ADP-ribosylation is a technically challenging PTM which has just emerged into the field of PTM-specific proteomics. But this fragile modifier requires special treatment on both a data acquisition and data processing level: it is highly labile under higher-energy collisional dissociation (HCD), and the degree of lability can depend on the site it modifies. Its behavior thus violates some assumptions on which proteomics algorithms are based. Here we present nonlocalized ADPr searching: a simple principle for maximizing sensitivity toward ADP-ribosylation when searching conventional HCD data. By scoring the strong fragment ions generally observed in ADPr spectra rather than the weak and often absent localization-dependent ions, nonlocalized searches are more sensitive. They also run significantly faster, due to reduced search space, and require no assumptions about which amino acids can be modified. We illustrate implementation in three search systems: Morpheus, MaxQuant, and MASCOT, and we also present a means of rapidly finding and extracting ADP-ribosylated peptide spectra from large datasets for more focused searching. This approach both improves identification of ADP-ribosylated peptides and avoids mis-localization of the modification sites.

Behavioral and Immunological Features Promoting the Invasive Performance of the Harlequin Ladybird Harmonia axyridis

The harlequin ladybird Harmonia axyridis is now established as a model to test hypotheses explaining why some species become successfully invasive, while others, even closely related ones, do not. In this review, we evaluate behavioral and immunological features that may play a role in the invasive performance of this model species. We discuss the behavioral traits and associated semiochemicals that promote the invasive success of H. axyridis. In particular, we consider (1) the aggregative behavior and the particular role of long-chain hydrocarbons; (2) the importance of sex pheromones and non-volatile chemicals in mate location and selection; (3) the use of allelochemicals for prey location; and (4) the nature of chemicals that protect against natural enemies. We also highlight the superior immune system of H. axyridis, which encompasses a broader spectrum of antimicrobial peptides (and higher inducible expression levels) compared with native ladybird beetles such as Adalia bipunctata and Coccinella septempunctata. The chemical defense compound harmonine and the antimicrobial peptides are thought to confer resistance against the abundant microsporidia carried by H. axyridis. These parasites can infect and kill native ladybird species feeding on H. axyridis eggs or larvae, supporting the hypothesis that intraguild predation plays a role in the ability of H. axyridis to outcompete native ladybird species in newly-colonized areas.

Gelatin speciation using real-time PCR and analysis of mass spectrometry-based proteomics datasets

Authentication of gelatin, an ingredient in food and drug products, is of interest with respect to some regulations and religion rules. Determination of the gelatin origin is particularly challenging because of the similarity in amino acid sequences of collagen types in different species. In this study, Polymerase Chain Reaction (PCR) technique using species-specific primers and also chemometrics analysis of mass spectral data were investigated to differentiate bovine, porcine and fish source of gelatin in commercial pure gelatin and gelatin-containing food and drug products. The specific PCR primer set was optimized using real-time PCR approach to routinely determine the gelatin source. Real-time PCR is sensitive to identify gelatin origin from traces of species-specific DNA. However, source determination is impossible when DNA is denatured or removed during production process. Alongside, chemometrics methods (PLS/DA and PCA) were used for mining LC/MS data sets to obtain patterns for discrimination of gelatin origins. LC/MS data sets involve MS spectrum of tryptic gelatin peptides generated from gelatin samples. Using PLS/DA method, a discrimination model is developed for identifying origin of the extracted gelatin. The method is practical to determine the halal authenticity of gelatin in the pure and processed products.

PDeep: Predicting MS/MS Spectra of Peptides with Deep Learning.

In tandem mass spectrometry (MS/MS)-based proteomics, search engines rely on comparison between an experimental MS/MS spectrum and the theoretical spectra of the candidate peptides. Hence, accurate prediction of the theoretical spectra of peptides appears to be particularly important. Here, we present pDeep, a deep neural network-based model for the spectrum prediction of peptides. Using the bidirectional long short-term memory (BiLSTM), pDeep can predict higher-energy collisional dissociation, electron-transfer dissociation, and electron-transfer and higher-energy collision dissociation MS/MS spectra of peptides with >0.9 median Pearson correlation coefficients. Further, we showed that intermediate layer of the neural network could reveal physicochemical properties of amino acids, for example the similarities of fragmentation behaviors between amino acids. We also showed the potential of pDeep to distinguish extremely similar peptides (peptides that contain isobaric amino acids, for example, GG = N, AG = Q, or even I = L), which were very difficult to distinguish using traditional search engines.

Global proteome and phosphoproteome dynamics indicate novel mechanisms of vitamin C induced dormancy in Mycobacterium smegmatis

Vitamin C has been found to affect mycobacteria in multiple ways, including increasing susceptibility to antimicrobial drugs, inducing dormancy, and having a bactericidal effect. However, the regulatory events mediating vitamin C related adaptations remain largely elusive. Ser/Thr/Tyr protein phosphorylation plays an important regulatory role in mycobacteria, contributing to environmental adaptation, including dormancy and drug resistance. This study utilised the model organism, Mycobacterium smegmatis, and TiO2 phosphopeptide enrichment combined with mass spectrometry-based proteomics methods to elucidate the mycobacterial signalling and regulatory response to sub-lethal concentrations of vitamin C. After initial validation of peptide spectra, 224 non-redundant phosphosites in 154 proteins were retained with high confidence. Data analysis revealed that 30 peptides were differentially phosphorylated with Vitamin C treatment, including novel phosphosites found on both PknG and GarA. Of these significant proteins, we validated 11 by parallel reaction monitoring of high-confidence phosphopeptides. Interestingly, 17/30 phosphopeptides were annotated as part of transmembrane proteins, suggesting that it is likely vitamin C triggers typical signal transduction events in which the protein periplasmic domain perceives environmental signals and the cytoplasmic domain is then phosphorylated. Finally, the diverse nature of phosphorylated proteins involved in signalling, transport, and carbohydrate biosynthesis indicates the extent of such regulatory phosphorylation events. Biological significanceOur findings provide new mechanistic insight into a coordinated network of signalling and regulatory responses to sub-lethal vitamin C in Mycobacterium smegmatis and provide evidence that vitamin C is able to act as a novel extracellular signalling molecule. Vitamin C treatment caused changes in both the proteome and phosphoproteome associated with response to oxidative stress, a shift in metabolic regulation and progression toward dormancy, as well as phospho-dependent activation of specific secretory pathways and activation of specific two component and Ser/Thr/Tyr protein kinase activities. This study confirms the potential of vitamin C as convenient means to study aspects of mycobacterial dormancy, including those regulated at post-translational level.

Fast simulations of multidimensional NMR spectra of proteins and peptides.

To simulate full multidimensional nuclear magnetic resonance spectra of peptides and proteins in a reasonable time frame, a strategy for separating the time-consuming full-density matrix calculations from the chemical shift prediction and calculation of coupling patterns is presented. The simulation setup uses SIMulation Program for SOlid-state NMR (SIMPSON) to calculate total correlation spectroscopy transfer amplitudes and average distances as a source for nuclear Overhauser effect spectroscopy transfer amplitudes. Simulated 1 H 1D, 2D total correlation spectroscopy, and 2D nuclear Overhauser effect spectroscopy nuclear magnetic resonance spectra of peptides with sequence Pro─Ala─Gly─Tyr─Asn and Asn─Phe─Gly─Ala─Ile─Leu and of ubiquitin are presented. In all cases, the simulations lasted from a few seconds to tens of seconds on a normal laptop computer.

Library Design-Facilitated High-Throughput Sequencing of Synthetic Peptide Libraries.

A methodology to achieve high-throughput de novo sequencing of synthetic peptide mixtures is reported. The approach leverages shotgun nanoliquid chromatography coupled with tandem mass spectrometry-based de novo sequencing of library mixtures (up to 2000 peptides) as well as automated data analysis protocols to filter away incorrect assignments, noise, and synthetic side-products. For increasing the confidence in the sequencing results, mass spectrometry-friendly library designs were developed that enabled unambiguous decoding of up to 600 peptide sequences per hour while maintaining greater than 85% sequence identification rates in most cases. The reliability of the reported decoding strategy was additionally confirmed by matching fragmentation spectra for select authentic peptides identified from library sequencing samples. The methods reported here are directly applicable to screening techniques that yield mixtures of active compounds, including particle sorting of one-bead one-compound libraries and affinity enrichment of synthetic library mixtures performed in solution.

Nutritional immunology: Diversification and diet-dependent expression of antimicrobial peptides in the black soldier fly Hermetia illucens

The black soldier fly Hermetia illucens is used for the bioconversion of organic waste into feed for livestock and aquaculture, and is economically among the most important farmed insects in the world. The larvae can be fed on agricultural waste and even liquid manure, resulting in highly unpredictable pathogen levels and dietary conditions. Here we show that H. illucens larvae express a remarkably expanded spectrum of antimicrobial peptides (AMPs), many of which are induced by feeding on a diet containing high bacterial loads. The addition of sulfonated lignin, cellulose, chitin, brewer's grains or sunflower oil revealed the diet-dependent expression profiles of AMPs in the larvae. The highest number of AMPs and the highest levels of AMP expression were induced by feeding larvae on diets supplemented with protein or sunflower oil. Strikingly, the diet-dependent expression of AMPs translated into diet-dependent profiles of inhibitory activities against a spectrum of bacteria, providing an intriguing example for the emerging field of nutritional immunology. We postulate that the fine-tuned expression of the expanded AMP repertoire mediates the adaptation of the gut microbiota to the digestion of unusual diets, and this feature could facilitate the use of H. illucens for the bioconversion of organic waste.

Identification of species- and tissue-specific proteins using proteomic strategy

Proteomic technologies have proven to be very effective for detecting biochemical changes in meat products, such as changes in tissue- and species-specific proteins. In the tissues of cattle, pig, horse and camel M. longissimus dorsi both tissue- and species specific proteins were detected using two dimensional electrophoresis. Species-specific isoforms of several muscle proteins were also identified. The identified and described proteins of cattle, pig, horse and camel skeletal muscles (including mass spectra of the tryptic peptides) were added to the national free access database “Muscle organ proteomics”. This research has enabled the development of new highly sensitive technologies for meat product quality control against food fraud.