Comparative Proteomic Analysis of Differentially Expressed Proteins in the Earthworm Eisenia fetida during Escherichia coli O157:H7 Stress

Effects of soybean oil exposure on the survival, reproduction, biochemical responses, and gut microbiome of the earthworm Eisenia fetida

With increasing production of kitchen waste, cooking oil gradually enters the soil, where it can negatively affect soil fauna. In this study, we explored the effects of soybean oil on the survival, growth, reproduction, tissue structure, biochemical responses, mRNA expression, and gut microbiome of earthworms (Eisenia fetida). The median lethal concentration of soybean oil was found to be 15.59%. Earthworm growth and reproduction were significantly inhibited following exposure to a sublethal concentration of soybean oil (1/3 LC50, 5.2%). The activity of the antioxidant enzymes total superoxide dismutase (T-SOD), peroxidase (POD), and catalase (CAT) were affected under soybean oil exposure. The glutathione (GSH) content decreased significantly, whereas that of the lipid peroxide malondialdehyde (MDA) increased significantly after soybean oil exposure. mRNA expression levels of the SOD, metallothionein (MT), lysenin and lysozyme were significantly upregulated. The abundance of Bacteroides species, which are related to mineral oil repair, and Muribaculaceae species, which are related to immune regulation, increased within the earthworm intestine. These results indicate that soybean oil waste is toxic to earthworms. Thus, earthworms deployed defense mechanisms involving antioxidant system and gut microbiota for protection against soybean oil exposure-induced stress.

Epigenetic regulations enhance adaptability and valorization efficiency in Eisenia fetida and Eudrilus eugeniae during vermicomposting of textile sludge: Insights on repair mechanisms of metal-induced genetic damage and oxidative stress

Genotoxicity-based assessments of vermitechnology for textile-sludge valorization have rarely been attempted. Therefore, waste sanitization and epigenetic stress-regulation efficiency of Eisenia fetida and Eudrilus eugeniae were evaluated in silk (DSPS) and cotton (CPWS) processing sludge-based vermibeds. Vermicomposting resulted in greater C, N, and P recovery than composting. Earthworm population reduced by 6-50% in DSPS/CPWS, while it significantly increased in cow dung (CD) mixed DSPS/CPWS. The Cr, Cd, Pb, and Zn accumulation efficiency of earthworms was higher in DSPS-based feedstocks than CPWS. However, metal-rich sludge elevated oxidative stress, causing greater inhibition of cell viability and DNA damage in Eudrilus than in Eisenia. Although histo-architecture of chloragogenous tissues was perturbed, earthworms combatted metal-induced lipid peroxidation via the activation of catalase, superoxide-dismutase, and reduced-glutathione. Correlation statistics revealed that genetic integrity in earthworms was restored through DNA-methyltransferase activity, especially in DSPS/CPWS + CD vermibeds. Overall, Eisenia was a healthier choice than Eudrilus for sustainable valorization of textile-sludge.

Proteomic analysis using isobaric tags for relative and absolute quantification technology reveals mechanisms of toxic effects of tris (1,3-dichloro-2-propyl) phosphate on RAW264.7 macrophage cells

Tris (1,3-dichloro-2-propyl) phosphate (TDCIPP) is one of the most commonly used organophosphorus flame retardants. Immuno-toxicity induced by TDCIPP is becoming of increasing concern. However, effects of TDCIPP on immune cells and mechanisms resulting in those effects are poorly understood. In this study, it was determined, for the first time, by use of isobaric tags for relative and absolute quantification (iTRAQ) based proteomic techniques expression of global proteins in RAW264.7 cells exposed to 10 μM TDCIPP. A total of 180 significantly differentially expressed proteins (DEPs) were identified. Of these, 127 were up-regulated and 53 were down-regulated. The DEPs associated with toxic effects of TDCIPP were then screened by use of Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes for enrichment analysis. Results showed that these DEPs were involved in a number of pathways including apoptosis, DNA damage, cell cycle arrest, immune-toxicity, and signaling pathways, such as the Toll-like receptor, PPAR and p53 signaling pathways. The complex regulatory relationships between different DEPs, which might play an important role in cell death were also observed in the form of a protein-protein interaction network. Meanwhile, mitochondrial membrane potential (MMP) in RAW264.7 cells after TDCIPP treatment was also analyzed, the collapse of the MMP was speculated to play an important role in TDCIPP induced apoptosis. Moreover, some of the important regulator proteins discovered in this study, such as Chk1, Aurora A, would provide novel insight into the molecular mechanisms involved in toxic responses to TDCIPP.

Fluoroquinolone antibiotics and organophosphate pesticides induce carbonylation on Eisenia fetida muscle proteins

Protein carbonylation is an irreversible oxidative modification that has been associated with a decrease in the quality and nutritional value of products of animal origin. Generally, the carbonylation is attributed to processes of slaughter, processing, and cold storage of products. However, in vitro studies have shown that fluoroquinolone and organophosphate pesticides residues at their maximum residue limits (MRL) can promote carbonylation of animal proteins. Though, this effect on in vivo conditions has not yet been evaluated. Thus, Eisenia fetida was chosen as a model to assay their oxidant effect. For this, adult earthworms were exposed to artificial soil contaminated with ciprofloxacin, danofloxacin, fenthion, and diazinon at three concentrations (0.5, 1.0, and 1.5 MRL) for 28 days. Then, these were purged and sacrificed to obtain the muscle region between the anus and preclitellum. The muscle samples were cold macerated to obtain muscle proteins, which were used for protein quantification, determination of carbonyl levels, and carbonyl protein profiles employing Bradford, Dot-blot, and Western blot assays, respectively. The results showed that at each concentration assayed, all pollutants induced significant carbonylation respect to control (p < 0.05). Additionally, mass spectrometry-based analysis (MALDI-TOF/TOF) identified actin as the protein most susceptible to carbonylation promoted by these substances. Therefore, these findings show for the first time the oxidant power of fluoroquinolones and organophosphates pesticides at MRLs concentrations on muscle proteins under in vivo conditions. Fact causes concern due to the homology of muscle proteins in eukaryotes, which allow to hypothesize that this effect could also be experienced by proteins from food-producing animals in the same way that observed in in vitro studies.

Vermicomposting Process to Endosulfan Lactone Removal in Solid Substrate Using Eisenia fetida

Pesticide by-products found in soil are usually more toxic and persistent than the pesticides themselves. For example, Endosulfan lactone (EL) (a by-product of the organochloride pesticide endosulfan). EL is created by the enzymatic activity (and related oxidative processes) of microorganisms in the soil. A sustainable method of EL removal is the introduction of Eisenia fetida earthworm. In this paper, it will be demonstrated the impact of vermicomposting process related to Eisenia fetida earthworm on EL by measuring initial and final concentrations of the compound and overall enzymatic activity in sterile and non-sterile solid substrate over 56 days. As a baseline, it be observed there were higher EL removals in non-sterile solid substrate (90.86%) at day 5 than in sterile solid substrate (83.86%) at day 14. In samples with Eisenia fetida, the presence of EL in non-sterile solid substrate was 36%, however in sterile solid substrate it was only 18% at day 1 and 7, with a maximum enzyme activity of 0.4659 mmol/mg protein per min at day 7. The evidence found in this study suggests that EL removal in a non-sterile solid substrate is higher when a vermicomposting is present and that the influence of microorganisms from the solid substrate with the earthworm, increases removal.

Amynthas corticis genome reveals molecular mechanisms behind global distribution

Earthworms (Annelida: Crassiclitellata) are widely distributed around the world due to their ancient origination as well as adaptation and invasion after introduction into new habitats over the past few centuries. Herein, we report a 1.2 Gb complete genome assembly of the earthworm Amynthas corticis based on a strategy combining third-generation long-read sequencing and Hi-C mapping. A total of 29,256 protein-coding genes are annotated in this genome. Analysis of resequencing data indicates that this earthworm is a triploid species. Furthermore, gene family evolution analysis shows that comprehensive expansion of gene families in the Amynthas corticis genome has produced more defensive functions compared with other species in Annelida. Quantitative proteomic iTRAQ analysis shows that expression of 147 proteins changed in the body of Amynthas corticis and 16 S rDNA sequencing shows that abundance of 28 microorganisms changed in the gut of Amynthas corticis when the earthworm was incubated with pathogenic Escherichia coli O157:H7. Our genome assembly provides abundant and valuable resources for the earthworm research community, serving as a first step toward uncovering the mysteries of this species, and may provide molecular level indicators of its powerful defensive functions, adaptation to complex environments and invasion ability.

iTRAQ-based quantitative proteomic analysis of the earthworm Eisenia fetida response to Escherichia coli O157:H7

Soil environment contaminated by Escherichia coli O157:H7 which come from the waste of infected animals. Earthworms can live in the pathogens-polluted soil by their innate immunity. How the proteins of earthworms E. fetida will response to E. coli O157:H7-contaminated-soil still unclear? To identify the defense proteins under E. coli O157:H7 stress, we performed a proteomic analysis of earthworm under E. coli O157:H7 exposure through an iTRAQ technology. In total, we found 283 non-redundant proteins, including fibrinolytic protease 1, lombricine kinase, lysozyme, gelsolin, coelomic cytolytic factor-1, antimicrobial peptide lumbricin-l, lysenin, and et al. The proteins participate in metabolic processes, transcription, defense response to bacterium, translation, response to stress, and transport. The study will contribute to understand why earthworm can live in the pathogens-polluted environment.

Effect of enrofloxacin on the proteome of earthworms

The environmental and human health risks of veterinary drugs are becoming public health issues. Enrofloxacin (EF) is an extensively used animal-specific antibacterial agent that leaves drug residues in the environment. This study investigated the proteomic response of the earthworm Eisenia fetida to EF exposure. Earthworms were exposed to EF in soil at 1-500mg·kg^-1, and samples were collected at intervals during a 28 day period. The extracted proteins were separated by two dimensional electrophoresis to detect differentially expressed proteins (DEPs) in EF-exposed earthworms. In total, 35 unique DEPs were found. These proteins were subjected to MALDI-TOF/TOF-MS analysis and identified through comparison of their mass spectra with those in protein databases. The DEPs were grouped on the basis of their function, into metabolism, stress-related, transport, transcription, and predicted/hypothetical protein categories. Knowledge of proteins that are induced or repressed by EF in earthworms could provide insight into mechanisms of sub-clinical physiological effects of xenobiotic residues in the environment, and may also help understand synergy between pollutants. As several DEPs in E. fetida showed similarity to human protein sequences, E. fetida has potential as an indicator species to assess the environmental and biological risks of drug residues.

Protective role of metallothionein during regeneration in Eisenia andrei exposed to cadmium

Lumbricid earthworms are often exposed to simultaneous action of various environmental stressors like soil contamination, temperature fluctuation or predators' attacks, which may induce extrusion of coelomocyte-containing coelomic fluid or loss of tail segments. If the injuries are not lethal, renewal of the immune-competent cells and soluble components of coelomic fluid and/or the regeneration of tail segments occurs. The aim of our investigations was to test the hypothesis that exposure of adult earthworms Eisenia andrei to cadmium-polluted soil at room temperature (RT) and/or low temperature (6°C) have adverse effects on restoration of experimentally depleted coelomocytes or on regeneration of amputated posterior segments. Intact control earthworms and their experimental counterparts subjected to electrostimulation-induced coelomocyte depletion or surgical amputation of posterior segments were maintained either in control soil or in soil spiked with cadmium chloride (500mg/kg air-dried soil) at RT or 6°C. Four weeks after the beginning of experiments, cadmium accumulation in earthworm bodies was significantly lower at 6°C than at room temperature. The numbers of restored cells and fluorophore contents were hardly affected by temperature or cadmium. However, cocoon production was reduced by cadmium and completely abolished at 6°C and regeneration of amputated posterior segments was inhibited in cold but was enhanced by cadmium exposure at RT. Independently on the temperature, the 4-week cadmium exposure of adult earthworms was connected with significantly upregulated expression of Cd-metallothionein (but not of catalase, lysenin and phytochelatin) in coelomocytes.

Toxic responses of Perna viridis hepatopancreas exposed to DDT, benzo(a)pyrene and their mixture uncovered by iTRAQ-based proteomics and NMR-based metabolomics

Dichlorodiphenyltrichloroethane (DDT) and benzo(a)pyrene (BaP) are environmental estrogens (EEs) that are ubiquitous in the marine environment. In the present study, we integrated isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomic and nuclear magnetic resonance (NMR)-based metabolomic approaches to explore the toxic responses of green mussel hepatopancreas exposed to DDT (10μg/L), BaP (10μg/L) and their mixture. The metabolic responses indicated that BaP primarily disturbed energy metabolism and osmotic regulation in the hepatopancreas of the male green mussel P. viridis. Both DDT and the mixture of DDT and BaP perturbed the energy metabolism and osmotic regulation in P. viridis. The proteomic responses revealed that BaP affected the proteins involved in energy metabolism, material transformation, cytoskeleton, stress responses, reproduction and development in green mussels. DDT exposure could change the proteins involved in primary metabolism, stress responses, cytoskeleton and signal transduction. However, the mixture of DDT and BaP altered proteins associated with material and energy metabolism, stress responses, signal transduction, reproduction and development, cytoskeleton and apoptosis. This study showed that iTRAQ-based proteomic and NMR-based metabolomic approaches could effectively elucidate the essential molecular mechanism of disturbances in hepatopancreas function of green mussels exposed to environmental estrogens.

Metabolite and gene expression responses in juvenile flounder Paralichthys olivaceus exposed to reduced salinities

Seawater salinity is one of the most important changeable environmental factors influencing the behavior, survival, growth and production of marine organisms. In this work, metabolite and gene expression profiles were used to elucidate the biological effects of reduced salinities in juvenile flounder Paralichthys olivaceus. Metabolic profiling indicated that both reduced salinities (23.3‰ and 15.6‰) enhanced proteolysis and disturbed osmotic regulation and energy metabolism in juvenile flounder P. olivaceus. Furthermore, the low salinity (15.6‰) enhanced anaerobic metabolism indicated by the elevated lactate in flounder tissue extracts. Gene expression profiles exhibited that reduced salinities could induce immune stress and oxidative stress and disturb energy metabolism in juvenile flounder P. olivaceus. In addition, reduced salinities might promote the growth and gonadal differentiation in juvenile flounder P. olivaceus.

Proteomics study revealed altered proteome of Dichogaster curgensis upon exposure to fly ash

Fly ash is toxic and its escalating use as a soil amendment and disposal by dumping into environment is receiving alarming attention due to its impact on environment. Proteomics technology is being used for environmental studies since proteins respond rapidly when an organism is exposed to a toxicant, and hence soil engineers such as earthworms are used as model organisms to assess the toxic effects of soil toxicants. This study adopted proteomics technology and profiled proteome of earthworm Dichogaster curgensis that was exposed to fly ash, with main aim to elucidate fly ash effects on cellular and metabolic pathways. The functional classification of identified proteins revealed carbohydrate metabolism (14.36%), genetic information processing (15.02%), folding, sorting and degradation (10.83%), replication and repair (3.95%); environmental information processing (2.19%), signal transduction (9.61%), transport and catabolism (17.27%), energy metabolism (6.69%), etc. in the proteome. Proteomics data and functional assays revealed that the exposure of earthworm to fly ash induced protein synthesis, up-regulation of gluconeogenesis, disturbed energy metabolism, oxidative and cellular stress, and mis-folding of proteins. The regulation of ubiquitination, proteasome and modified alkaline comet assay in earthworm coelomocytes suggested DNA-protein cross link affecting chromatin remodeling and protein folding.

The interactive effects of mercury and selenium on metabolic profiles, gene expression and antioxidant enzymes in halophyte Suaeda salsa

Suaeda salsa is the pioneer halophyte in the Yellow River Delta and was consumed as a popular vegetable. Mercury has become a highly risky contaminant in the sediment of intertidal zones of the Yellow River Delta. In this work, we investigated the interactive effects of mercury and selenium in S. salsa on the basis of metabolic profiling, antioxidant enzyme activities and gene expression quantification. Our results showed that mercury exposure (20 μg L(-1)) inhibited plant growth of S. salsa and induced significant metabolic responses and altered expression levels of INPS, CMO, and MDH in S. salsa samples, together with the increased activities of antioxidant enzymes including SOD and POD. Overall, these results indicated osmotic and oxidative stresses, disturbed protein degradation and energy metabolism change in S. salsa after mercury exposures. Additionally, the addition of selenium could induce both antagonistic and synergistic effects including alleviating protein degradation and aggravating osmotic stress caused by mercury.

A 2-DE-based proteomic study on the toxicological effects of cisplatin in L02 cells

Cisplatin is a chemotherapeutic agent for the treatment of various cancers. In this study, cisplatin-induced effects were characterized in vitro model of human liver cells (L02) using 2-DE-based proteomics. Results indicated that different cisplatin treatments primarily induced disturbances in protein synthesis and oxidative stress via differential mechanisms. Since the experimental concentrations of cisplatin described a hormesis effect in cell proliferation of L02 cells, it was expected to reveal the hormesis effects using proteomic markers. However, only confilin-1 was commonly up-regulated in three concentrations of cisplatin treatments showing a hormesis effects with a U-shape regulation. These results were highly consistent with many other toxico-proteomic studies, indicating that the toxico-proteomic responses based on dose-dependent protein responses were incongruent with the theoretically linear or hormetic concentration-effect relationship. Our findings suggested that a macroscopic hormesis phenomenon on the cell proliferation could not be reflected by proteomic responses induced by cisplatin treatments.

Combined metabolome and proteome analysis of the mantle tissue from Pacific oyster Crassostrea gigas exposed to elevated pCO2

Ocean acidification (OA) has been found to affect an array of normal physiological processes in mollusks, especially posing a significant threat to the fabrication process of mollusk shell. In the current study, the impact of exposure to elevated pCO2 condition was investigated in mantle tissue of Crassostrea gigas by an integrated metabolomic and proteomic approach. Analysis of metabolome and proteome revealed that elevated pCO2 could affect energy metabolism in oyster C. gigas, marked by differentially altered ATP, succinate, MDH, PEPCK and ALDH levels. Moreover, the up-regulated calponin-2, tropomyosins and myosin light chains indicated that elevated pCO2 probably caused disturbances in cytoskeleton structure in mantle tissue of oyster C. gigas. This work demonstrated that a combination of proteomics and metabolomics could provide important insights into the effects of OA at molecular levels.

iTRAQ-based quantitative proteomic analyses on the gender-specific responses in mussel Mytilus galloprovincialis to tetrabromobisphenol A

Tetrabromobisphenol A (TBBPA) accounts for the largest production of brominated flame-retardants (BFRs) along the Laizhou Bay in China and is the most widely used BFR in industrial products. It can induce diverse toxicities including hepatotoxicity, nephrotoxicity, neurotoxicity and endocrine disrupting effects in mammalian and fish models. In this work, we applied iTRAQ-based proteomics to investigate the gender-specific responses in mussel Mytilus galloprovincialis to TBBPA. Thirty-one proteins were differentially expressed in hepatopancreas between male and female mussels, which clearly indicated the biological differences between male and female mussels at the protein level. After exposure of TBBPA (18.4 nmol/L) for one month, a total of 60 proteins were differentially expressed in response to the TBBPA treatment in mussel hepatopancreas, among which 33 and 29 proteins were significantly altered in TBBPA-treated male and female mussel samples, respectively. Only two of the 60 proteins were commonly altered in both male and female mussel samples exposed to TBBPA. Based on KEGG analysis, these differentially expressed proteins of TBBPA-induced effects were assigned to several groups, including cytoskeleton, reproduction and development, metabolism, signal transduction, gene expression, stress response and apoptosis. Overall, results indicated that TBBPA exposure could induce apoptosis, oxidative and immune stresses and disruption in energy, protein and lipid metabolisms in both male and female mussels with different mechanisms. This work suggested that the gender differences should be considered in ecotoxicoproteomics.

Proteomic and metabolomic analysis reveal gender-specific responses of mussel Mytilus galloprovincialis to 2,2',4,4'-tetrabromodiphenyl ether (BDE 47)

Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame-retardants (BFRs) that are widely used in industrial products and have posed potential risk on the coastal environment of the Laizhou Bay in China. They are of great concern due to their toxicities, such as hepatotoxicity, carcinogenecity, neurotoxicity, immunotoxicity and endocrine disrupting effects in animals. In this work, we focused on the gender-specific responses of BDE 47 in mussel Mytilus galloprovincialis using a combined proteomic and metabolomic approach. Metabolic responses indicated that BDE 47 mainly caused disturbance in energy metabolism in male mussel gills. For female mussel samples, disruption in both osmotic regulation and energy metabolism was found in terms of differential metabolic profiles. Proteomic responses revealed that BDE 47 induced cell apoptosis and reduced reactive oxygen species (ROS) production in both male and female mussels, disturbance in protein homeostasis in male mussels as well as disturbance in female mussel proteolysis based on the differential proteomic biomarkers. Overall, these results confirmed the gender-specific responses in mussels to BDE 47 exposures. This work demonstrated that an integrated metabolomic and proteomic approach could provide an important insight into the toxicological effects of environmental pollutant to organisms.

Responses of Mytilus galloprovincialis to bacterial challenges by metabolomics and proteomics

Pathogens can cause diseases and lead to massive mortalities of aquaculture animals and substantial economic loss. In this work, we studied the responses induced by Micrococcus luteus and Vibrio anguillarum in gill of mussel Mytilus galloprovincialis at protein and metabolite levels. Metabolic biomarkers (e.g., amino acids, betaine, ATP) suggested that both M. luteus and V. anguillarum induced disturbances in energy metabolism and osmotic regulation. The unique and some more remarkably altered metabolic biomarkers (threonine, alanine, aspartate, taurine, succinate) demonstrated that V. anguillarum could cause more severe disturbances in osmotic regulation and energy metabolism. Proteomic biomarkers (e.g., goose-type lysozyme 2, matrilin, ependymin-related protein, peptidyl-prolyl cis-trans isomerases) indicated that M. luteus caused immune stress, and disturbances in signaling pathways and protein synthesis. However, V. anguillarum mainly induced oxidative stress and disturbance in energy metabolism in mussel gills indicated by altered procollagen-proline dioxygenase, protein disulfide isomerase, nucleoside diphosphate kinases, electron transfer flavoprotein and glutathione S-transferase. This work confirmed that an integration of proteomics and metabolomics could provide an insightful view into the effects of pathogens to the marine mussel M. galloprovincialis.

Comparative proteomic analysis of the sun- and freeze-dried earthworm Eisenia fetida with differentially thrombolytic activities

The dried earthworm is a traditional thrombolytic medicine in East Asia. Its thrombolytic mechanism has been extensively studied. However, the effects of drying process on thrombolysis were rarely investigated. Herein, we compared the thrombolytic activity of earthworm Eisenia fetida processed by sun-drying to that by freeze-drying. Fibrin plate and blood clot lysis assays showed that freeze-dried earthworms gave dramatically higher fibrinolytic and thrombolytic activities than the sun-dried earthworms. To address the thrombolytic difference, comparative proteomic analysis was carried out using fibrin zymography and two-dimensional gel electrophoresis (2-DE). The freeze- and sun-dried earthworms generated remarkably different 2-DE protein spot patterns. A total of 126 differential protein spots were detected, 83 of them were identified by matrix-assisted laser desorption/ionization-tandem time-of-flight mass spectrometry and database searching with 13 quantitative changes and 70 qualitative changes. Five of these differential proteins were identified as fibrinolytic proteases (lumbrokinases), responsible for dissolving fibrin, the main protein component of thrombus. The total abundance of these fibrinolytic proteases in the freeze-dried earthworms was significantly higher, consistent with the results of fibrin zymography. Therefore, the higher concentration of fibrinolytic enzymes along with their broad substrate specificity explained the stronger fibrinolytic and thrombolytic activities of the freeze-dried earthworms. This study suggests that freeze-drying represents an improved processing method for earthworm as the thrombolytic therapy in the future.

BIOLOGICAL SIGNIFICANCE

Thrombosis has become one of the biggest concerns all over the world. The dried earthworms have been intensively used as thrombolytic agents. Its thrombotic mechanism has been studied by the modern pharmacological researches. However, the drying procedure of the earthworm and its effects on the thrombolysis were rarely investigated. The present study compared the thrombolytic effects of the freeze-dried and the normal dried earthworm E. fetida. To better understand the underlying mechanisms for differential thrombolytic effects, the fibrin zymography and the two-dimensional gel electrophoresis (2-DE) were employed to identify sets of differential proteins. Therefore, this study provides not only the comparative proteomic analysis but also molecular mechanism underlying the differential thrombolytic effects.

Nitrogen under- and over-supply induces distinct protein responses in maize xylem sap

Xylem sap primarily transports water and mineral nutrients such as nitrogen (N) from roots to shoots in vascular plants. However, it remains largely unknown how nitrogenous compounds, especially proteins in xylem sap, respond to N under- or over-supply. We found that reducing N supply increased amino-N percentage of total N in maize (Zea mays L.) xylem sap. Proteomic analysis showed that 23 proteins in the xylem sap of maize plants, including 12 newly identified ones, differentially accumulated in response to various N supplies. Fifteen of these 23 proteins were primarily involved in general abiotic or biotic stress responses, whereas the other five proteins appeared to respond largely to N under- or over-supply, suggesting distinct protein responses in maize xylem upon N under- and over-supply. Furthermore, one putative xylanase inhibitor and two putative O-glycosyl hydrolases had preferential gene expression in shoots.

Differential expression of genes in the earthworm Eisenia fetida following exposure to Escherichia coli O157:H7

In this study, suppression subtractive hybridization was used to construct forward and reverse cDNA libraries to identify genes involved in the response of Eisenia fetida after exposure to Escherichia coli O157:H7. We cloned 1428 cDNAs or expressed sequence tags (ESTs), of which 738 were confirmed to be differentially expressed on dot blotting analysis. A total of 394 good-quality ESTs (GenBank dbEST accession numbers HO001170-HO001563) were obtained from the raw clone sequences after cleaning. The genes were associated with metabolism (10%), transport (10%), translation (5%), immunity (2%), and the cytoskeleton (1%). Thirteen candidates were selected to assess expression levels in earthworms exposed to artificially contaminated soil by real-time PCR. The translated amino acid sequences of clones were similar to fibrinolytic protease 1, extracellular globin-3, myosin essential light chain, lumbrokinase, lysozyme, ferritin, ATP synthase F0 subunit 6, and hsp 70. Characterization of differential gene expression in the earthworm E. fetida on exposure to E. coli O157:H7 expands our understanding of the molecular mechanisms of interactions at the earthworm-pathogen interface.