Comparative gut proteomics study revealing adaptive physiology of Eurasian spruce bark beetle, Ips typographus (Coleoptera: Scolytinae)

The bark beetle, Ips typographus (L.), is a major pest of Norway spruce, Picea abies (L.), causing enormous economic losses globally. The adult stage of the I. typographus has a complex life cycle (callow and sclerotized); the callow beetles feed ferociously, whereas sclerotized male beetles are more aggressive and pioneers in establishing new colonies. We conducted a comparative proteomics study to understand male and female digestion and detoxification processes in callow and sclerotized beetles. Proteome profiling was performed using high-throughput liquid chromatography-mass spectrometry. A total of >3000 proteins were identified from the bark beetle gut, and among them, 539 were differentially abundant (fold change ±2, FDR <0.05) between callow and sclerotized beetles. The differentially abundant proteins (DAPs) mainly engage with binding, catalytic activity, anatomical activity, hydrolase activity, metabolic process, and carbohydrate metabolism, and hence may be crucial for growth, digestion, detoxification, and signalling. We validated selected DAPs with RT-qPCR. Gut enzymes such as NADPH-cytochrome P450 reductase (CYC), glutathione S-transferase (GST), and esterase (EST) play a crucial role in the I. typographus for detoxification and digesting of host allelochemicals. We conducted enzyme activity assays with them and observed a positive correlation of CYC and GST activities with the proteomic results, whereas EST activity was not fully correlated. Furthermore, our investigation revealed that callow beetles had an upregulation of proteins associated with juvenile hormone (JH) biosynthesis and chitin metabolism, whereas sclerotized beetles exhibited an upregulation of proteins linked to fatty acid metabolism and the TCA cycle. These distinctive patterns of protein regulation in metabolic and functional processes are specific to each developmental stage, underscoring the adaptive responses of I. typographicus in overcoming conifer defences and facilitating their survival. Taken together, it is the first gut proteomic study comparing males and females of callow and sclerotized I. typographus, shedding light on the adaptive ecology at the molecular level. Furthermore, the information about bark beetle handling of nutritionally limiting and defence-rich spruce phloem diet can be utilized to formulate RNAi-mediated beetle management.

Organophosphate diesters (DAPs) and hydroxylated organophosphate flame retardants (HO-OPFRs) as biomarkers of OPFR contamination in a typical freshwater food chain

Organophosphate flame retardants (OPFRs) can rapidly biotransform into two types of metabolites in biota: (1) organophosphate diesters (DAPs) and (2) hydroxylated OPFRs (HO-OPFRs). Therefore, the levels of parent OPFRs alone are not sufficient to indicate OPFR pollution in biological organisms. This study analyzed 12 OPFR metabolites, including 6 DAPs and 6 HO-OPFRs, in a typical freshwater food chain consisted of crucian carp, catfish, mud carp, snakehead, and oriental river prawn. The total concentrations of OPFR metabolites were comparable to those of parent OPFRs, and ranged from 0.65 to 17 ng/g ww. Bis(2-butoxyethyl) 3'-hydroxy-2-butoxyethyl phosphate (14%-77%), di-n-butyl phosphate (DNBP) (6.7%-24%), bis(1-chloro-2-propyl) phosphate (BCIPP) (0.7%-35%), and 1-hydroxy-2-propyl bis(1-chloro-2-propyl) phosphate (BCIPHIPP) (6.0%-24%) were the major OPFR metabolites. Various aquatic species exhibited significant differences in their OPFR metabolite/parent ratios (MPR) (p < 0.05), indicating varying biotransformation potentials of different organisms for various OPFRs. The growth-independent accumulation of tri-n-butyl phosphate (TNBP), tris(chloro-2-propyl) phosphate (TCIPP), triphenyl phosphate, and 2-ethylhexyl diphenyl phosphate in mud carps could be explained by their biotransformation potential. A significant negative correlation was found between the concentration of bis(2-butoxyethyl) phosphate and δ15N values (p < 0.05), with a calculated trophic magnification factor (TMF) of 0.66. Significant positive correlations were observed between BCIPP and TCIPP (R2 = 0.25, p < 0.05), as well as between DNBP and TNBP (R2 = 0.30, p < 0.01), implying that these two DAPs could be used as biomarkers to quantitatively assess TCIPP and TNBP contamination in wild aquatic organisms.

iTRAQ-based proteome analysis of porcine group A rotavirus-infected porcine IPEC-J2 intestinal epithelial cells

Porcine rotavirus (PoRV), particularly group A, is one of the most important swine pathogens, causing substantial economic losses in the animal husbandry industry. To improve understanding of host responses to PoRV infection, we applied isobaric tags for relative and absolute quantification (iTRAQ) labeling coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) to quantitatively identify the differentially expressed proteins in PoRV-infected IPEC-J2 cells and confirmed the differentially accumulated proteins (DAPs) expression differences by performing RT-qPCR and Western blot analysis. Herein, in PoRV- and mock-infected IPEC-J2 cells, relative quantitative data were identified for 4724 proteins, 223 of which were DAPs (125 up-accumulated and 98 down-accumulated). Bioinformatics analyses further revealed that a majority of the DAPs are involved in numerous crucial biological processes and signaling pathways, such as metabolic process, immune system process, amino acid metabolism, energy metabolism, immune system, MHC class I peptide loading complex, Hippo signaling pathway, Th1 and Th2 cell differentiation, antigen processing and presentation, and tubule bicarbonate reclamation. The cellular localization prediction analysis indicated that these DAPs may be located in the Golgi apparatus, nucleus, peroxisomal, cytoplasm, mitochondria, extracellular, plasma membrane, and endoplasmic reticulum (ER). Expression levels of three up-accumulated (VAMP4, IKBKE, and TJP3) or two down-accumulated (SOD3 and DHX9) DAPs upon PoRV infection, were further validated by RT-qPCR and Western blot analysis. Collectively, this work is the first time to investigate the protein profile of PoRV-infected IPEC-J2 cells using quantitative proteomics; these findings provide valuable information to better understand the mechanisms underlying the host responses to PoRV infection in piglets. SIGNIFICANCE: The proteomics analysis of this study uncovered the target associated with PoRV-induced innate immune response or cellular damage, and provided relevant insights into the molecular functions, biological processes, and signaling pathway in these targets. Out of these 223 DAPs, the expression levels of three up-accumulated (VAMP4, IKBKE, and TJP3) and two down-accumulated (SOD3 and DHX9) DAPs upon PoRV infection, have been further validated using RT-qPCR and Western blot analysis. These outcomes could uncover how PoRV manipulated the cellular machinery, which could further our understanding of PoRV pathogenesis in piglets.

Quantification of glyphosate and other organophosphorus compounds in human urine via ion chromatography isotope dilution tandem mass spectrometry

Organophosphorus pesticides are the most used pesticides in the United States. Most organophosphorus pesticides are composed of a phosphate (or phosphorothioate or phosphorodithioate) moiety and a variable organic group. Organophosphorus pesticides are scrutinized by regulatory bodies and agencies because of their toxicity or suspected carcinogenicity. Upon exposure, organophosphorus pesticides and their metabolites eliminate in urine; these urinary biomarkers are useful to evaluate human exposure. We developed a method using stable isotope dilution, ion chromatography tandem mass spectrometry for quantification in urine of 6 O,O-dialkylphosphates, metabolites of organophosphorus insecticides, and glyphosate, the most used herbicide in the United States. With simple and minimal sample preparation, the analytical method is selective and sensitive (limits of detection are 0.2-0.8 μg/L), accurate (>85%) and precise (relative standard deviation <20%), depending on the analyte. To assess the suitability of the method in real exposure scenarios, we analyzed samples collected anonymously from subjects with suspected exposure to pesticides (n = 40) or who had been on an organic diet (n = 50). We detected glyphosate in 80% of subjects reporting an organic diet and in 78% of those with suspected glyphosate exposure; concentrations ranged from <0.2 to 28.6 μg/L. Median concentrations were 0.39 μg/L for the organic diet group and 0.40 μg/L for individuals with suspected exposure. Interestingly, interquartile ranges were considerably higher among those reporting pesticide exposure (0.63 μg/L) than those consuming organic diets (0.42 μg/L). These data suggest that the method meets typical validation benchmark values and is sensitive to investigate background exposures in the general population.

Biomonitoring of common organophosphate metabolites in hair and urine of children from an agricultural community

Levels of dialkylphosphate (DAP) metabolites were measured in hair and urine of children that lived close to intensively farmed areas of Almeria (Southeast Spain). The levels were used as proxies for exposure of these children to organophosphate pesticides (OPs). Determinants of exposure to DAPs were also examined. Urine and hair samples were collected from 222 children aged 3-11 years and information on lifestyle and dietary habits was collected from questionnaires administered to mothers. Urinary DAPs were analyzed by ultra-high performance liquid-chromatography coupled to triple-quadrupole tandem mass-spectrometry (UHPLC-QqQ-MS/MS) and hair DAPs by gas-chromatography coupled to mass spectrometry (GC-MS). Detection rates ranged from 21.8% for diethylphosphate (DEP) and diethylthiophosphate (DETP) to 35.9% for dimethylphosphate (DMP) in urine; and from 42.3% for DETP to 92.8% for DMP in hair. Diethyldithiophosphate (DEDTP) was detected in 0.5% of urine samples (one child), and in 26.6% of children's hair samples. A lack of correlation was observed for individual DAP metabolites and ΣDAPs between urine and hair samples, except for DEDTP. Urinary DAP levels of our child population were lower than those reported for children from other countries, including NHANES 1999-2000 data. The main determinants of hair DAP levels were age, sex, vegetable intake, parental exposure to pesticides at work, time spent playing indoors, monthly income and father's education level. Conversely, none of the predictors studied was significantly associated with urinary DAPs except age. Overall, hair has advantages over urine as it is easier to collect, handle and store, and allows for assessment of cumulative exposure to OPs, thus providing a greater insight for human biomonitoring.

Biomonitoring of dialkylphosphate metabolites (DAPs) in urine and hair samples of sprayers and rural residents of Crete, Greece

PURPOSE

The aim of this study was to evaluate the exposure of rural residents (control group) and occupational exposed population group of sprayers to organophosphorus pesticides (OPs) by measuring their non-specific dialkylphosphate metabolites (DAPs) in hair and in urine samples. All subjects (n=120) were residents of the municipality of Ierapetra, an area of intensive cultivation in Crete, Greece.

METHODS

The determined OPs metabolites were DMP, DEP, DETP and DEDTP. Two different approaches were used for the analysis of the collected samples; solid-liquid extraction with sonication for hair and liquid-liquid extraction for urine. Gas chromatography-mass spectrometry (GC-MS) analysis was performed after derivatization of the isolated analytes.

RESULTS AND DISCUSSION

The detection rates of DMP, DEP and DETP for both control and sprayers groups were high in both matrices, ranging from 91% to 100%. DEDTP was detected only in 9% of sprayers hair samples, while its detection rates in urine samples ranged from 83% to 90% for both population groups. Data analysis revealed significantly higher sumDAPs levels in urine of sprayers than in the urine of control group (p<0.001) and this is justified since sampling occurred during spraying periods. SumDAPs levels in hair samples of the sprayers were also significantly higher than in the hair of control group (p<0.001), confirming the long-term exposure to OPs. SumDAPs found levels in urine and hair samples of subjects were significantly correlated (Spearman׳s rho=0.728, p<0.001). Our study confirmed the elevated levels of DAPs in hair and urine samples in occupationally exposed group of sprayers in comparison to control group, even detected levels were similar in logarithmic scale.