Sulfur Relay System Research Articles

Impact of camptothecin exposures on the development and larval midgut metabolomic profiles of Spodoptera frugiperda

Spodoptera frugiperda is an economic agricultural pest that has invaded many countries around the world and caused huge losses in grain production. Camptothecin (CPT) is one of the botanical compounds with insecticidal activity and has the potential for pest control. However, the effects of CPT on development and metabolism of S. frugiperda remain unknown. In this study, we have investigated the adverse effects of 1.0 and 5.0 mg/kg CPT exposures on the growth and development of S. frugiperda. Our results found that 1.0 and 5.0 mg/kg CPT treatments altered the parameters of the life cycle, including inducing larval mortality, altering the weight of larvae, pupae, and adults, the larval duration, and decreasing the pupation rate and emergence rate. In addition, comparative metabolomics analysis was performed in the larval midgut of S. frugiperda to explore the toxicity mechanism of CPT. A total of 261 and 348 differential metabolites were identified in the groups with 1.0 and 5.0 mg/kg CPT treatments, respectively. Further analysis found that pantothenate and CoA biosynthesis, sulfur relay system, selenocompound metabolism, and fatty acid biosynthesis pathways were significantly altered by 5.0 mg/kg CPT exposure. Our results provided new insight into the toxicological mechanisms of CPT against S. frugiperda and laid the foundation for the field application of CPT in pest control.

Proteomic analysis revealed gender-related differences in the skin mucus proteome of discus fish (Symphysodon haraldi) during the parental and non-parental care periods

The discus fish, Symphysodon spp., a South American cichlid, has a unique parental care behavior where fry bite on parental skin mucus after hatching. In this study, we used LC-MS/MS technique to compare the skin mucus proteome composition of male or female discus fish during parental and non-parental care periods. By multivariate statistical analysis, we found clear separations between different periods and between different sexes of mucus proteome. Compared with non-parental female fish, parental female fish had 283 up-regulated and 235 down-regulated expressed proteins. Compared with non-parental male fish, parental male fish had 169 up-regulated and 120 down-regulated expressed proteins. The differentially expressed proteins for male fish were enriched in sulfur relay system, mucin type O-glycan biosynthesis and antigen processing and presentation pathways, while those for female fish were enriched in sulfur relay system, steroid biosynthesis and complement and coagulation cascades pathways. During the parental care, both male and female discus showed an enhanced lipid metabolism, producing more phospholipids and cholesterol. The difference is that male discus had increased tricarboxylic acid cycle producing more energy during the parental care, while females produced more nucleotides especially guanylic acid. Our study could provide new insights into the understanding of the unique mucus supply behavior of discus fish based on proteomic change.

Exploration of Response Mechanisms in the Gills of Pacific Oyster (Crassostrea gigas) to Cadmium Exposure through Integrative Metabolomic and Transcriptomic Analyses.

Marine mollusks, including oysters, are highly tolerant to high levels of cadmium (Cd), but the molecular mechanisms underlying their molecular response to acute Cd exposure remain unclear. In this study, the Pacific oyster Crassostrea gigas was used as a biological model, exposed to acute Cd stress for 96 h. Transcriptomic analyses of their gills were performed, and metabolomic analyses further validated these results. In our study, a total of 111 differentially expressed metabolites (DEMs) and 2108 differentially expressed genes (DEGs) were identified under acute Cd exposure. Further analyses revealed alterations in key genes and metabolic pathways associated with heavy metal stress response. Cd exposure triggered physiological and metabolic responses in oysters, including enhanced oxidative stress and disturbances in energy metabolism, and these changes revealed the biological response of oysters to acute Cd stress. Moreover, oysters could effectively enhance the tolerance and detoxification ability to acute Cd exposure through activating ABC transporters, enhancing glutathione metabolism and sulfur relay system in gill cells, and regulating energy metabolism. This study reveals the molecular mechanism of acute Cd stress in oysters and explores the molecular mechanism of high tolerance to Cd in oysters by using combined metabolomics and transcriptome analysis.

Neuroprotective effect of chitosan oligosaccharide on alcohol-induced hippocampal injury using proteomic analysis.

Alcoholism is a serious public health problem, and the abuse of drinking seriously damages the health of people. Chitosan oligosaccharides (COSs) are small-molecule oligosaccharides with amino groups that have many unique properties. The neuroprotective effect of COS on alcohol-induced hippocampal injury in Sprague-Dawley (SD) rats was investigated. The discrimination ratio of the COS group in the Y-maze experiment was 59.3% higher than that of the ETOH group. Meanwhile, the discrimination index was less than 0 in the ETOH group but greater than 0 in the COS group during the object recognition test. The cells in the COS group were more tightly arranged than those in the ETOH group. Proteomics was used to identify differentially expressed proteins in the hippocampus. There were 27 differentially expressed proteins in the COS and ETOH group for further bioinformatic analysis. There are three enriched pathway categories, namely, primary immunodeficiency, hedgehog signaling, and sulfur relay system. Next, sonic hedgehog signaling pathway-related proteins were verified through western blotting. The protein expression level of β-arrestin-2 in the COS group was 2.85 times higher than that in the ETOH group. This work may contribute to understanding the underlying mechanism of the neuroprotective effect of COS against alcohol-induced hippocampal injury in SD rats.

Characterization of MicroRNAs and Gene Expression in ACC Oxidase RNA Interference-Based Transgenic Bananas.

Banana (Musa acuminata, AAA group) is a typically respiratory climacteric fruit. Previously, genes encoding ACC oxidase, one of the key enzymes in ethylene biosynthesis, Mh-ACO1 and Mh-ACO2 in bananas were silenced individually using RNAi interference technology, and fruit ripening of transgenic bananas was postponed. Here, the differential expression of miRNAs and their targeted mRNAs were analyzed in the transcriptomes of fruits at the third ripening stage, peel color more green than yellow, from the untransformed and RNAi transgenic bananas. Five significantly differentially expressed miRNAs (mac-miR169a, mac-miR319c-3p, mac-miR171a, mac-miR156e-5p, and mac-miR164a-5p) were identified. The predicted miRNA target genes were mainly enriched in six KEGG pathways, including 'sulfur relay system', 'protein digestion and absorption', 'histidine metabolism', 'pathogenic E. coli infection', 'sulfur metabolism', and 'starch and sucrose metabolism'. After ethylene treatment, the expression of ACC oxidase silencing-associated miRNAs was down-regulated, and that of their target genes was up-regulated along with fruit ripening. The evolutionary clustering relationships of miRNA precursors among 12 gene families related to fruit ripening were analyzed. The corresponding expression patterns of mature bodies were mainly concentrated in flowers, fruits, and leaves. Our results indicated that ethylene biosynthesis is associated with miRNAs regulating the expression of sulfur metabolism-related genes in bananas.

Unconventional secretion of Magnaporthe oryzae effectors in rice cells is regulated by tRNA modification and codon usage control.

Microbial pathogens deploy effector proteins to manipulate host cell innate immunity, often using poorly understood unconventional secretion routes. Transfer RNA (tRNA) anticodon modifications are universal, but few biological functions are known. Here, in the rice blast fungus Magnaporthe oryzae, we show how unconventional effector secretion depends on tRNA modification and codon usage. We characterized the M. oryzae Uba4-Urm1 sulfur relay system mediating tRNA anticodon wobble uridine 2-thiolation (s2U34), a conserved modification required for efficient decoding of AA-ending cognate codons. Loss of s2U34 abolished the translation of AA-ending codon-rich messenger RNAs encoding unconventionally secreted cytoplasmic effectors, but mRNAs encoding endoplasmic reticulum-Golgi-secreted apoplastic effectors were unaffected. Increasing near-cognate tRNA acceptance, or synonymous AA- to AG-ending codon changes in PWL2, remediated cytoplasmic effector production in Δuba4. In UBA4+, expressing recoded PWL2 caused Pwl2 super-secretion that destabilized the host-fungus interface. Thus, U34 thiolation and codon usage tune pathogen unconventional effector secretion in host rice cells.

Development of Expressed Sequence Tag–Simple Sequence Repeat Markers Related to the Salt-Stress Response of Kenaf (Hibiscus cannabinus)

Kenaf is one of the most important natural cannabis plants. Molecular marker-assisted breeding is vital for accelerating the breeding process of kenaf. However, the number of kenaf markers is insufficient for molecular marker-assisted breeding. Using transcriptome sequencing data for salt-stressed kenaf plants, the number and distribution of simple sequence repeats (SSRs) and single nucleotide variations (SNVs) in the expressed sequences were determined. The objectives of this study were to elucidate the sequence variations in kenaf genes expressed in response to salt stress and to identify stable and dependable molecular markers. Primers were designed for SSR loci and then EST-SSR molecular markers were generated. The subsequent analyses revealed that 30.50% of the unigenes contained SSR motifs, most of which were single nucleotides followed by trinucleotides and dinucleotides. The unigenes containing SSRs were mostly associated with kenaf salt tolerance. Additionally, 10,483 SNVs were detected in contig sequences. Of the 3995 differentially expressed genes encoding interacting proteins, 1297 contained SSRs. Most of these genes were associated with metabolic pathways (e.g., 03000 transcription factors, B09132 signal transduction, and 04122 sulfur relay system). We designed 20 pairs of EST-SSR primers to genotype 30 kenaf varieties (lines), of which 9 primer pairs were ideal for genotyping (e.g., 1 highly polymorphic marker and 2 moderately polymorphic markers). The primer pairs designed for the EST-SSR markers in the kenaf genome may be useful SSR molecular markers for future research on kenaf. The verified polymorphic markers may be applicable to the molecular marker-assisted breeding of salt-tolerant kenaf varieties.

Effects of Bacillus licheniformis on the Growth Performance, Antioxidant Capacity, Ileal Morphology, Intestinal Short Chain Fatty Acids, and Colonic Microflora in Piglets Challenged with Lipopolysaccharide

The aim of the present study was to investigate the effects of Bacillus licheniformis (BL) on the growth performance, antioxidant capacity, ileal morphology, intestinal fecal short-chain fatty acids, and microflora of weaned piglets challenged with lipopolysaccharide (LPS). Piglets were assigned into three groups: basal diet (Con), a basal diet with added 109 CFU B. licheniformis/kg (BLl), and a basal diet with added 1010 CFU B. licheniformis/kg (BLh). On day 28, BLh piglets were intraperitoneally injected with LPS (CBL) and sterilized saline water (BL), Con piglets were injected with LPS (LPS) and sterilized saline water (Con), with the injections being administered for three consecutive days. The average daily gain significantly increased from day 1 to day 28 and the feed: gain ratio decreased with BL supplementation compared with the Con group. Supplementation with BLl and BLh reduced the diarrhea rate in piglets. Serum catalase activity increased and malondialdehyde concentration decreased in the CBL treatment group compared with the LPS treatment group. Both BL and CBL treatments increased the ileal villus length/crypt depth ratio compared with Con and LPS treatments. BL administration significantly increased colonic propionic and isobutyric acid concentrations compared with Con treatment. Both BL and CBL piglets had significantly increased fecal acetic, propionic, and butyric acid levels compared with LPS piglets. Analysis of the colonic microbial metagenome showed that Prevotella species were the predominant bacteria in piglets treated with BL and CBL. The CBL-treated piglets had higher scores for lysine biosynthesis, arginine biosynthesis, sulfur relay system, and histidine metabolism. BL-treated piglets had higher scores for glycosaminoglycan biosynthesis-keratan sulfate, oxidative phosphorylation, and pyruvate and carbon metabolism.

Uncovering the regulation effect of modified clay on toxin production in Alexandrium pacificum: From physiological insights

As a common dinoflagellate, Alexandrium pacificum can produce paralytic shellfish toxins (PSTs). It can be removed from water by Polyaluminium chloride modified clay (PAC-MC), but it is unclear whether PAC-MC can prevent PSTs content and toxicity from increasing and whether PAC-MC can stimulate PSTs biosynthesis by A. pacificum. Effect of PAC-MC on PSTs and the physiological mechanism were analysed here. The results showed total PSTs content and toxicity decreased respectively by 34.10 % and 48.59 % in 0.2 g/L PAC-MC group at 12 days compared with control group. And the restriction of total PSTs by PAC-MC was mainly achieved via inhibition of algal cell proliferation, by affecting A. pacificum physiological processes and changing phycosphere microbial community. Meanwhile, single-cell PSTs toxicity did not increase significantly throughout the experiment. Moreover, A. pacificum treated with PAC-MC tended to synthesize sulfated PSTs such as C1&2. Mechanistic analysis showed that PAC-MC induced upregulation of sulfotransferase sxtN (related to PSTs sulfation), and functional prediction of bacterial community also showed significant enrichment of “sulfur relay system” after PAC-MC treatment, which might also promote PSTs sulfation. The results will provide theoretical guidance for the application of PAC-MC to field control of toxic Alexandrium blooms.

Molecular Influence of Resiniferatoxin on the Urinary Bladder Wall Based on Differential Gene Expression Profiling.

Resiniferatoxin (RTX) is a potent capsaicin analog used as a drug for experimental therapy to treat neurogenic disorders associated with enhanced nociceptive transmission, including lower urinary tract symptoms. The present study, for the first time, investigated the transcriptomic profile of control and RTX-treated porcine urinary bladder walls. We applied multistep bioinformatics and discovered 129 differentially expressed genes (DEGs): 54 upregulated and 75 downregulated. Metabolic pathways analysis revealed five significant Kyoto Encyclopedia of Genes and Genomes (KEGG) items ('folate biosynthesis', 'metabolic pathways', 'sulfur relay system', 'sulfur metabolism' and 'serotonergic synapse') that were altered after RTX intravesical administration. A thorough analysis of the detected DEGs indicated that RTX treatment influenced the signaling pathways regulating nerve growth, myelination, axon specification, and elongation. Many of the revealed DEGs are involved in the nerve degeneration process; however, some of them were implicated in the initiation of neuroprotective mechanisms. Interestingly, RTX intravesical installation was followed by changes in the expression of genes involved in synaptic plasticity and neuromodulation, including 5-HT, H2S, glutamate, and GABA transmission. The obtained results suggest that the toxin may exert a therapeutic, antinociceptive effect not only by acting on TRPV1 receptors.

Multiple mechanisms collectively mediate tungsten homeostasis and resistance in Citrobacter sp. Lzp2

Tungsten (W) is an emerging contaminant, and current knowledge on W resistance profiles of microorganisms remains scarce and fragmentary. This study aimed to explore the physiological responses of bacteria under W stress and to resolve genes and metabolic pathways involved in W resistance using a transcriptome expression profiling assay. The results showed that the bacterium Citrobacter sp. Lzp2, screened from W-contaminated soil, could tolerate hundreds of mM W(VI) with a 50% inhibiting concentration of ∼110 mM. To cope with W stress, Citrobacter sp. Lzp2 secreted large amounts of proteins through the type VI secretory system (T6SS) to chelate W oxoanions via carboxylic groups in extracellular polymeric substances (EPS), and could transport cytosolic W outside via the multidrug efflux pumps (mdtABC and acrD). Intracellular W is probably bound by chaperone proteins and metal-binding pterin (tungstopterin) through the sulfur relay system. We propose that tetrathionate respiration is a new metabolic pathway for cellular W detoxification likely producing thio-tungstate. We conclude that multiple mechanisms collectively mediate W homeostasis and resistance in Citrobacter sp. Lzp2. Our results have important implications not only for understanding the intricate regulatory network of W homeostasis in microbes but also for bio-recovery and bioremediation of W in contaminated environments.

Identification and prediction of functions for drought-responsive microRNAs in sugar beet (Beta vulgaris)

Context Drought is a common abiotic stress affecting crop yield and quality worldwide. Sugar beet (Beta vulgaris L.) is a temperate crop that contributes greatly to world sucrose production and is affected by frequent drought. MicroRNAs (miRNAs) have been demonstrated to play an important role in plant abiotic stress responses. Protein-coding genes associated with drought resistance have been identified in sugar beet; however, studies on miRNAs involved in drought stress response are lacking. Aims The present study focused on analysing miRNAs in sugar beet and their roles in drought stress response. Method Small-RNA libraries were constructed from leaves of plants subjected to drought stress and well-watered conditions. High-throughput sequencing and bioinformatics analysis were used to investigate the genome-wide quantity of miRNAs and identify possible drought response regulatory effects. Key results Deep sequencing identified 49 known miRNAs and 59 new miRNAs. According to the Kyoto Encyclopaedia of Genes and Genomes (KEGG), the sulfur relay system was significantly enriched under drought stress. Co-regulated pairs between miR156a-5p, novel_18 and novel_41, and their target genes BVRB_6g136190, BVRB_009610 and BVRB_6g136680 were observed, suggesting a negative feedback modulation involved in the miRNA pathways. Conclusions Our results indicate that certain metabolic pathways such as the sulfur relay system are activated under drought conditions. Implications The results aid understanding of the mechanisms of drought response at the molecular level and may enable tools to be devised that enhance drought resistance in sugar beet.

Analysis of Transcriptome Difference between Blood-Fed and Starved Tropical Bed Bug, Cimex hemipterus (F.) (Hemiptera: Cimicidae).

Simple SummaryBed bugs are well known for their extreme resilience to starvation. The molecular mechanisms behind this ability, however, are little known. Thus, the whole transcriptomes of blood-fed and starved bed bugs from the species Cimex hemipterus (tropical bed bugs) were sequenced and compared. The transcriptome of tropical bed bugs was initially annotated. Following differentially expressed genes (DEGs) analysis, regulated transcripts were mostly identified in biological processes during blood-feeding and starvation. The results provide an overview of the functional genes proportion of this species and a deeper understanding of the bed bug’s molecular mechanism of resistance to blood feeding and starvation.The reference transcriptome for Cimex hemipterus (tropical bed bug) was assembled de novo in this study, and differential expression analysis was conducted between blood-fed and starved tropical bed bug. A total of 24,609 transcripts were assembled, with around 79% of them being annotated against the Eukaryotic Orthologous Groups (KOG) database. The transcriptomic comparison revealed several differentially expressed genes between blood-fed and starved bed bugs, with 38 of them being identifiable. There were 20 and 18 genes significantly upregulated in blood-fed and starved bed bugs, respectively. Differentially expressed genes (DEGs) were revealed to be associated with regulation, metabolism, transport, motility, immune, and stress response; endocytosis; and signal transduction. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed an enrichment of genes encoding steroid biosynthesis, glycosaminoglycan biosynthesis, butanoate metabolism, and autophagy in both blood-fed and starved bed bugs. However, in blood-fed bed bugs, genes involved in histidine metabolism, caffeine metabolism, ubiquinone/terpenoid-quinone biosynthesis, and sulfur relay system were enriched. On the other hand, starvation activates genes related to nicotinate and nicotinamide metabolism, fatty acid elongation, terpenoid backbone biosynthesis, metabolism of xenobiotics by cytochrome P450, riboflavin metabolism, apoptosis, and protein export. The present study is the first to report a de novo transcriptomic analysis in C. hemipterus and demonstrated differential responses of bed bugs in facing blood-feeding and starvation.

The cytosolic Arabidopsis thaliana cysteine desulfurase ABA3 delivers sulfur to the sulfurtransferase STR18

The biosynthesis of many sulfur-containing molecules depends on cysteine as a sulfur source. Both the cysteine desulfurase (CD) and rhodanese (Rhd) domain–containing protein families participate in the trafficking of sulfur for various metabolic pathways in bacteria and human, but their connection is not yet described in plants. The existence of natural chimeric proteins containing both CD and Rhd domains in specific bacterial genera, however, suggests a general interaction between these proteins. We report here the biochemical relationships between two cytosolic proteins from Arabidopsis thaliana, a Rhd domain–containing protein, the sulfurtransferase 18 (STR18), and a CD isoform referred to as ABA3, and compare these biochemical features to those of a natural CD–Rhd fusion protein from the bacterium Pseudorhodoferax sp. We observed that the bacterial enzyme is bifunctional exhibiting both CD and STR activities using l-cysteine and thiosulfate as sulfur donors but preferentially using l-cysteine to catalyze transpersulfidation reactions. In vitro activity assays and mass spectrometry analyses revealed that STR18 stimulates the CD activity of ABA3 by reducing the intermediate persulfide on its catalytic cysteine, thereby accelerating the overall transfer reaction. We also show that both proteins interact in planta and form an efficient sulfur relay system, whereby STR18 catalyzes transpersulfidation reactions from ABA3 to the model acceptor protein roGFP2. In conclusion, the ABA3–STR18 couple likely represents an uncharacterized pathway of sulfur trafficking in the cytosol of plant cells, independent of ABA3 function in molybdenum cofactor maturation.

Molecular mechanism of locus coeruleus involved in acupuncture anti-myocardial ischemia based on transcriptome sequencing

To explore the molecular mechanism of locus coeruleus（LC） involved in electroacupuncture (EA) anti myocardial ischemia. Twenty-four SD rats were randomly divided into sham-operation, model, EA and EA +lesion groups, with 6 rats in each group. The acute myocardial ischemia (AMI) model was established by ligation of the left anterior descending branch of coronary artery. EA (2 Hz/15 Hz, 1 mA) was applied to bilateral "Shenmen" (HT7) -"Tongli" (HT5) and the middle-point between HT7 and HT5 for 30 min, once daily for 3 days. For rats of the EA +lesion group, the virus (300 nL) was injected into bilateral LC before EA treatment. Serum aspartate aminotransferase (AST) was detected by ELISA. The gene expression profiles of rat heart were detected by transcriptome sequencing, the differentially expressed genes were screened, and Gene Ontology (GO) functional classification and Kyoto Encyclopedia of genes and genomes (KEGG) metabolic pathway enrichment analysis were performed. Compared with the sham-operation group, serum AST content was significantly increased in the model group (P<0.01). Following the intervention, serum AST was significantly reduced in the EA group (P<0.01), while the serum AST in the EA + lesion group was significantly higher compared with the EA group (P<0.05). Differential expression analysis showed that 1 138 differentially expressed genes were screened out between the model group and the sham-operation group, 1 330 differentially expressed genes between model and EA group, and 804 differentially expressed genes between EA and EA + lesion group. Among them, 218 differential genes were involved in the regulation of EA anti-myocardial ischemia in LC. GO functional classification analysis showed that these differentially expressed genes mainly involved in cell processes, metabolic processes and biological regulation in biological processes. KEGG pathway analysis showed that these differentially expressed genes were enriched in sulfur relay system, thiamine metabolism, glutathione metabolism, C5 branch dicarboxylic acid metabolism, cell adhesion molecules and Th1 and Th2 cell differentiation. EA intervention has a positive effect in anti-myocardial ischemia, which may be related to the sulfur relay system, thiamine metabolism, glutathione metabolism, C5 branch dicarboxylic acid metabolism, cell adhesion molecules and Th1 and Th2 cell differentiation involved in LC.

Mucosa-associated gut microbiome in Japanese patients with functional constipation.

The number of patients with chronic constipation is increasing in Japan. We investigated the gut mucosa-associated microbiome in Japanese patients with functional constipation. Diagnosis was made according to the Rome IV criteria. Mucosal samples were obtained by gentle brushing of mucosa surfaces. The gut microbiome was analyzed using 16S rRNA gene sequencing. There were no significant differences in bacteria α-diversity such as richness and evenness. The PCoA indicated significant structural differences between the constipation group and healthy controls (p=0.017 for unweighted and p=0.027 for weighted). The abundance of the phylum Bacteroidetes was significantly higher in the constipation group. The abundance of the genera Streptococcus, Fusobacterium, Comamonas, and Alistipes was significantly higher in the constipation group. The abundance of the genera Acinetobacter, Oscillospilla, Mucispirillum, Propinibacterium, and Anaerotruncus was significantly lower in the constipation group. In the constipation group, the proportion of genes responsible for sulfur metabolism, selenocompound metabolism, sulfur relay system was significantly higher and the proportion of d-arginine and d-ornithine metabolism and flavonoid biosynthesis was significantly lower. In conclusion, we identified differences of the mucosa-associated microbiome between Japanese patients with functional constipation and healthy controls. The mucosa-associated microbiome of functional constipation was characterized by higher levels of Bacteroidetes (Alistipes).

Comparative Proteome Analysis of Shewanella putrefaciens WS13 Mature Biofilm Under Cold Stress.

Worldwide, Shewanella putrefaciens is the predominant seafood spoilage microorganism during cold storage. This bacterium can attach to biotic/abiotic surfaces to form biofilms which contribute to seafood quality degradation and shelf-life reduction. The mechanism of S. putrefaciens biofilm formation is not yet described. Crystal violet staining in combination with confocal laser scanning microscopy (CLSM) was used to study the sequence of events leading to the establishment of a mature biofilm at 4, 15, and 30°C. In addition, the main chemical constituents of the mature biofilm were determined by Raman spectroscopy (RM), whereas, comparative proteomic analysis was used to quantify changes in metabolic pathways and to find out underlying protein determinants. The physical dimensions of the mature biofilm, i.e., biomass, biovolume, and mean thickness, were higher at 4°C when compared to 15 and 30°C. The variations of proteins measured by RM confirmed the importance of proteins during the formation of a mature biofilm. Comparative proteomic analysis showed that siderophore and iron chelate transport proteins were down-regulated during mature biofilm formation. The down-regulated aforementioned proteins are involved in promoting iron storage in response to a higher demand for metabolic energy, whereas, the upregulated proteins of the sulfur relay system, pyrimidine metabolism, and purine metabolism are related to bacterial adaptability. Synthesis of proteins related to cold stress was increased and proteins involved in aminoacyl-tRNA biosynthesis were up-regulated, whereas, proteins involved in aminopeptidase activity were down-regulated. Proteolysis to scavenge energy was reduced as proteins involved in pyrophosphatase activity were up-regulated. Also extracellular eDNA was found which may play an important role in maintaining the stability of mature S. putrefaciens biofilm structures under cold stress. This work provides a better understanding of the role of proteins in mature biofilms. In addition, the biofilm formation mechanism of a psychrotrophic spoilage bacterial species at low temperature is explored, which may contribute to generating biofilm controlling strategies during seafood preservation and processing.

569-P: Plasma Metabolomic Profiling of Diabetic Macular Edema

Background: Diabetic macular edema (DME), a sight-threatening retinopathy, is a leading cause of vision loss in persons with diabetes mellitus. Despite strict control of systemic risk factors, a fraction of patients with diabetes develop DME, suggesting the existence of other potential pathogenic factors underlying DME. This study aimed to investigate the plasma metabotype of patients with DME and to identify novel metabolite markers for DME. Biomarkers identified from this study will provide scientific insight and new strategies for the early diagnosis and intervention of DME. Methods: To match clinical parameters between case and control subjects, patients with DME (DME, n=30) or those with diabetes but without DME (Control, n=30) were assigned to the present case-control study. Distinct metabolite profiles of serum were examined using liquid chromatography-mass spectrometry (LC-MS). Results: A total of 188 distinct metabolites between DME and Control groups were identified (VIP &amp;gt; 1, Fold Change &amp;gt; 1.5 or &amp;lt; 0.5, and P &amp;lt; 0.05). These metabolites mainly included Lipids and lipid-like molecules (71%), organic acids and derivatives (17%), Organic oxygen compounds (8%) and others. The distinct metabolites between DME and Control groups were enriched in 5 KEGG pathways, namely, lysine degradation, arachidonic acid metabolism, riboflavin metabolism, sulfur relay system, and thyroid hormone synthesis. Finally, 4 metabolites were selected as candidate biomarkers for DME, namely, Violaxanthin, uridine, D-Glucopyranuronic acid, and Capryloylglycine. The area under the curve for these biomarkers were 0.89, 0.85, 0.86, and 0.82, respectively. Conclusions: This study suggested that impairment in the metabolism and 4 potential metabolites were identified as metabolic dysregulation associated with DME, which might provide insights into potential new pathogenic pathways for DME. Disclosure X. Zhu: None. Funding National Key Research and Development Program of China (2017YFC0909600)

Transcriptional analysis reveals the relativity of acid tolerance and antimicrobial peptide resistance of Salmonella

The objective of this study was to comprehensively identify the target genes induced by acid stimulation in Salmonella, and to clarify the relativity of acid tolerance and antimicrobial peptide resistance. A clinical S. Typhimurium strain, S6, was selected and performed a transcriptome analysis under the acid tolerance response. In total, we found 1461 genes to be differentially expressed, including 721 up-regulated and 740 down-regulated genes. Functional annotation revealed differentially expressed genes to be associated with regulation, metabolism, transport, virulence, and motility. Interestingly, KEGG pathway analysis demonstrated that the induced genes by acid were enriched in cationic antimicrobial peptide resistance, sulfur relay system, ABC transporters, and two-component system pathway. Therein, PhoQ belonging to the two-component system PhoP-PhoQ that promotes virulence by detecting the macrophage phagosome and controls the transcript levels of many genes associated with the resistance to AMPs; MarA, a multiple antibiotic resistance factor; SapA, one of the encoding gene of sapABCDF operon that confers resistance to small cationic peptides of Salmonella; YejB, one of the encoding gene of yejABEF operon that confers resistance to antimicrobial peptides and contributes to the virulence of Salmonella, were all induced by acid stimulation, and could potentially explain that there is a correlation between acid tolerance and AMPs resistance, and finally affects the virulence of intracellular pathogenic bacteria.

Genome-wide screening of Saccharomyces cerevisiae deletion mutants reveals cellular processes required for tolerance to the cell wall antagonist calcofluor white

We screened a haploid library of Saccharomyces cerevisiae single-gene deletion mutants to identify nonessential genes associated with increased sensitivity to or resistance against the cell wall antagonist calcofluor white. Through a genome-wide screen, we isolated 537 strains that had an altered growth rate relative to wild type, of which 485 showed increased sensitivity and 52 showed increased resistance to calcofluor white. The MAPK signaling pathway, N-glycan biosynthesis, endocytosis, vacuole acidification, autophagy, and the sulfur relay system were identified as being associated with calcofluor white sensitivity. Resistance genes were mainly involved in chitin metabolism and the RIM101 pathway or encoded several components of the ESCRT complexes or related to cysteine and methionine metabolism and RNA degradation. Further investigation indicated a clear global response network that S. cerevisiae relies on in the presence of the cell wall antagonist calcofluor white, which may help us to understand fungal cell wall remodeling and the mechanisms of toxicity of calcofluor white with respect to eukaryotic cells.