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61300.95034-Hydroxy-2-nonenal antimicrobial toxicity is neutralized by an intracellular pathogen. Pathogens encounter numerous antimicrobial responses during infection, including the reactive oxygen species (ROS) burst. ROS-mediated oxidation of host membrane poly-unsaturated fatty acids (PUFAs) generates the toxic alpha-beta carbonyl 4-hydroxy-2-nonenal (4-HNE). Although studied extensively in the context of sterile inflammation, research into 4-HNE's role during infection remains limited. Here, we found that 4-HNE is generated during bacterial infection, that it impacts growth and survival in a range of bacteria, and that the intracellular pathogen Listeria monocytogenes induces many genes in response to 4-HNE exposure. A component of the L. monocytogenes 4-HNE response is the expression of the genes lmo0103 and lmo0613, deemed rha1 and rha2 (reductase of host alkenals), respectively, which code for two NADPH-dependent oxidoreductases that convert 4-HNE to the product 4-hydroxynonanal (4-HNA). Loss of these genes had no impact on L. monocytogenes bacterial burdens during murine or tissue culture infection. However, heterologous expression of rha1/2 in Bacillus subtilis significantly increased bacterial resistance to 4-HNE in vitro and promoted bacterial survival following phagocytosis by murine macrophages in an ROS-dependent manner. Thus, Rha1 and Rha2 are not necessary for 4-HNE resistance in L. monocytogenes but are sufficient to confer resistance to an otherwise sensitive organism in vitro and in host cells. Our work demonstrates that 4-HNE is a previously unappreciated component of ROS-mediated toxicity encountered by bacteria within eukaryotic hosts.202133955352
10310.9469IL-1 receptor regulates S100A8/A9-dependent keratinocyte resistance to bacterial invasion. Previously, we reported that epithelial cells respond to exogenous interleukin (IL)-1α by increasing expression of several genes involved in the host response to microbes, including the antimicrobial protein complex calprotectin (S100A8/A9). Given that S100A8/A9 protects epithelial cells against invading bacteria, we studied whether IL-1α augments S100A8/A9-dependent resistance to bacterial invasion of oral keratinocytes. When inoculated with Listeria monocytogenes, human buccal epithelial (TR146) cells expressed and released IL-1α. Subsequently, IL-1α-containing media from Listeria-infected cells increased S100A8/A9 gene expression in naïve TR146 cells an IL-1 receptor (IL-1R)-dependent manner. Incubation with exogenous IL-1α decreased Listeria invasion into TR146 cells, whereas invasion increased with IL-1R antagonist. Conversely, when S100A8/A9 genes were knocked down using short hairpin RNA (shRNA), TR146 cells responded to exogenous IL-1α with increased intracellular bacteria. These data strongly suggest that infected epithelial cells release IL-1α to signal neighboring keratinocytes in a paracrine manner, promoting S100A8/A9-dependent resistance to invasive L. monocytogenes.201222031183
80820.9467Exposure of Legionella pneumophila to low-shear modeled microgravity: impact on stress response, membrane lipid composition, pathogenicity to macrophages and interrelated genes expression. Here, we studied the effect of low-shear modeled microgravity (LSMMG) on cross stress resistance (heat, acid, and oxidative), fatty acid content, and pathogenicity along with alteration in expression of stress-/virulence-associated genes in Legionella pneumophila. The stress resistance analysis result indicated that bacteria cultivated under LSMMG environments showed higher resistance with elevated D-values at 55 °C and in 1 mM of hydrogen peroxide (H(2)O(2)) conditions compared to normal gravity (NG)-grown bacteria. On the other hand, there was no significant difference in tolerance (p < 0.05) toward simulated gastric fluid (pH-2.5) acid conditions. In fatty acid analysis, our result showed that a total amount of saturated and cyclic fatty acids was increased in LSMMG-grown cells; as a consequence, they might possess low membrane fluidity. An upregulated expression level was noticed for stress-related genes (hslV, htrA, grpE, groL, htpG, clpB, clpX, dnaJ, dnaK, rpoH, rpoE, rpoS, kaiB, kaiC, lpp1114, ahpC1, ahpC2, ahpD, grlA, and gst) under LSMMG conditions. The reduced virulence (less intracellular bacteria and less % of induce apoptosis in RAW 264.7 macrophages) of L. pneumophila under LSMMG conditions may be because of downregulation related genes (dotA, dotB, dotC, dotD, dotG, dotH, dotL, dotM, dotN, icmK, icmB, icmS, icmT, icmW, ladC, rtxA, letA, rpoN, fleQ, fleR, and fliA). In the LSMMG group, the expression of inflammation-related factors, such as IL-1α, TNF-α, IL-6, and IL-8, was observed to be reduced in infected macrophages. Also, scanning electron microscopy (SEM) analysis showed less number of LSMMG-cultivated bacteria attached to the host macrophages compared to NG. Thus, our study provides understandings about the changes in lipid composition and different genes expression due to LSMMG conditions, which apparently influence the alterations of L. pneumophila' stress/virulence response.202438305908
3330.9459Transgenic Silkworms Overexpressing Relish and Expressing Drosomycin Confer Enhanced Immunity to Multiple Pathogens. The sericulture industry faces substantial economic losses due to severe pathogenic infections caused by fungi, viruses, and bacteria. The development of transgenic silkworms against specific pathogens has been shown to enhance disease resistance against a particular infection. A single gene or its products that can confer protection against multiple pathogens is required. In an attempt to develop silkworms with enhanced immunity against multiple pathogens, we generated transgenic silkworm lines with an overexpressed NF-kB transcription factor, Relish 1, under two different promoters. Separately, a potent anti-fungal gene, Drosomycin, was also expressed in transgenic silkworms. Both Relish 1 and Drosomycin transgenic silkworms had single copy genomic integration, and their mRNA expression levels were highly increased after infection with silkworm pathogens. The overexpression of the Relish 1 in transgenic silkworms resulted in the upregulation of several defense-related genes, Cecropin B, Attacin, and Lebocin, and showed enhanced resistance to Nosema bombycis (microsporidian fungus), Nucleopolyhedrovirus (BmNPV), and bacteria. The Drosomycin expressing transgenic silkworms showed elevated resistance to N. bombycis and bacteria. These findings demonstrate the role of Relish 1 in long-lasting protection against multiple pathogens in silkworms. Further, the successful introduction of a foreign gene, Drosomycin, also led to improved disease resistance in silkworms.202235098482
880740.9455Dietary watermelon residue influencing the nonspecific immunity of juvenile Pseudorasbora parva. The study explored the improvement of disease resistance, non-specific immunity and anti-oxidation reactions for Pseudorasbora parva (PP) using dietary watermelon residue. The cumulative PP mortality and the pathogenic bacteria number in 15-45% groups reduced relative to those in control group (CK). Under 15-45% groups, AKP, ACP activities and akp, acp genes expression levels were increased markedly in nonspecific immunity system. Similarly, antioxidant response (SOD, CAT activities) and their genes was promoted also at 15-45% groups. Organic matter (vitamin and polyphenols) in watermelon residue improved AKP, ACP, SOD, CAT activities by increasing corresponding gene expressions. Theoretically, they could also function as stimulus signal, active center or composition to modulate enzyme activities and gene expressions. Besides, watermelon residue ameliorated NF-kB, mTOR responses pathway, and consequently suppressed Aeromonas hydrophila which augmented disease resistance.202134534653
60550.9452Conservation and diversity of the IrrE/DdrO-controlled radiation response in radiation-resistant Deinococcus bacteria. The extreme radiation resistance of Deinococcus bacteria requires the radiation-stimulated cleavage of protein DdrO by a specific metalloprotease called IrrE. DdrO is the repressor of a predicted radiation/desiccation response (RDR) regulon, composed of radiation-induced genes having a conserved DNA motif (RDRM) in their promoter regions. Here, we showed that addition of zinc ions to purified apo-IrrE, and short exposure of Deinococcus cells to zinc ions, resulted in cleavage of DdrO in vitro and in vivo, respectively. Binding of IrrE to RDRM-containing DNA or interaction of IrrE with DNA-bound DdrO was not observed. The data are in line with IrrE being a zinc peptidase, and indicate that increased zinc availability, caused by oxidative stress, triggers the in vivo cleavage of DdrO unbound to DNA. Transcriptomics and proteomics of Deinococcus deserti confirmed the IrrE-dependent regulation of predicted RDR regulon genes and also revealed additional members of this regulon. Comparative analysis showed that the RDR regulon is largely well conserved in Deinococcus species, but also showed diversity in the regulon composition. Notably, several RDR genes with an important role in radiation resistance in Deinococcus radiodurans, for example pprA, are not conserved in some other radiation-resistant Deinococcus species.201728397370
882860.9452Phenylalanine 4-Hydroxylase Contributes to Endophytic Bacterium Pseudomonas fluorescens' Melatonin Biosynthesis. Melatonin acts both as an antioxidant and as a growth regulatory substance in plants. Pseudomonas fluorescens endophytic bacterium has been shown to produce melatonin and increase plant resistance to abiotic stressors through increasing endogenous melatonin. However, in bacteria, genes are still not known to be melatonin-related. Here, we reported that the bacterial phenylalanine 4-hydroxylase (PAH) may be involved in the 5-hydroxytryptophan (5-HTP) biosynthesis and further influenced the subsequent production of melatonin in P. fluorescens. The purified PAH protein of P. fluorescens not only hydroxylated phenylalanine but also exhibited l-tryptophan (l-Trp) hydroxylase activity by converting l-Trp to 5-HTP in vitro. However, bacterial PAH displayed lower activity and affinity for l-Trp than l-phenylalanine. Notably, the PAH deletion of P. fluorescens blocked melatonin production by causing a significant decline in 5-HTP levels and thus decreased the resistance to abiotic stress. Overall, this study revealed a possible role for bacterial PAH in controlling 5-HTP and melatonin biosynthesis in bacteria, and expanded the current knowledge of melatonin production in microorganisms.202134868217
798570.9452Differential response of nonadapted ammonia-oxidising archaea and bacteria to drying-rewetting stress. Climate change is expected to increase the frequency of severe drought events followed by heavy rainfall, which will influence growth and activity of soil microorganisms, through osmotic stress and changes in nutrient concentration. There is evidence of rapid recovery of processes and adaptation of communities in soils regularly experiencing drying/rewetting and lower resistance and resilience in nonadapted soils. A microcosm-based study of ammonia-oxidising archaea (AOA) and bacteria (AOB), employing a grassland soil that rarely experiences drought, was used to test this hypothesis and also whether AOB were more resistant and resilient, through greater tolerance of high ammonia concentrations produced during drought and rewetting. Treated soils were dried, incubated for 3 weeks, rewetted, incubated for a further 3 weeks and compared to untreated soils, maintained at a constant moisture content. Nitrate accumulation and AOA and AOB abundance (abundance of respective amoA genes) and community composition (DGGE analysis of AOA amoA and AOB 16S rRNA genes) were poorly adapted to drying-rewetting. AOA abundance and community composition were less resistant than AOB during drought and less resilient after rewetting, at times when ammonium concentration was higher. Data provide evidence for poor adaptation of microbial communities and processes to drying-rewetting in soils with no history of drought and indicate niche differentiation of AOA and AOB associated with high ammonia concentration.201425070168
847580.9451Antibacterial Activity of Endophytic Bacteria Against Sugar Beet Root Rot Agent by Volatile Organic Compound Production and Induction of Systemic Resistance. The volatile organic compounds (VOCs) produced by endophytic bacteria have a significant role in the control of phytopathogens. In this research, the VOCs produced by the endophytic bacteria Streptomyces sp. B86, Pantoea sp. Dez632, Pseudomonas sp. Bt851, and Stenotrophomonas sp. Sh622 isolated from healthy sugar beet (Beta vulgaris) and sea beet (Beta maritima) were evaluated for their effects on the virulence traits of Bacillus pumilus Isf19, the causal agent of harvested sugar beet root rot disease. The gas chromatographymass spectrometry (GC-MS) analysis revealed that B86, Dez632, Bt851, and Sh622 produced 15, 28, 30, and 20 VOCs, respectively, with high quality. All antagonistic endophytic bacteria produced VOCs that significantly reduced soft root symptoms and inhibited the growth of B. pumilus Isf19 at different levels. The VOCs produced by endophytic bacteria significantly reduced swarming, swimming, and twitching motility by B. pumilus Isf19, which are important to pathogenicity. Our results revealed that VOCs produced by Sh622 and Bt851 significantly reduced attachment of B. pumilus Isf19 cells to sugar beetroots, and also all endophytic bacteria tested significantly reduced chemotaxis motility of the pathogen toward root extract. The VOCs produced by Dez632 and Bt851 significantly upregulated the expression levels of defense genes related to soft rot resistance. Induction of PR1 and NBS-LRR2 genes in sugar beetroot slices suggests the involvement of SA and JA pathways, respectively, in the induction of resistance against pathogen attack. Based on our results, the antibacterial VOCs produced by endophytic bacteria investigated in this study can reduce soft rot incidence.202235722285
873590.9447The Effect of Ice-Nucleation-Active Bacteria on Metabolic Regulation in Evergestis extimalis (Scopoli) (Lepidoptera: Pyralidae) Overwintering Larvae on the Qinghai-Tibet Plateau. Evergestis extimalis (Scopoli) is a significant pest of spring oilseed rape in the Qinghai-Tibet Plateau. It has developed resistance to many commonly used insecticides. Therefore, biopesticides should be used to replace the chemical pesticides in pest control. In this study, the effects of ice-nucleation-active (INA) microbes (Pseudomonas syringae 1.7277, P. syringae 1.3200, and Erwinia pyrifoliae 1.3333) on E. extimalis were evaluated. The supercooling points (SCP) were markedly increased due to the INA bacteria application when they were compared to those of the untreated samples. Specifically, the SCP of E. extimalis after its exposure to a high concentration of INA bacteria in February were -10.72 °C, -13.73 °C, and -14.04 °C. Our findings have demonstrated that the trehalase (Tre) genes were up-regulated by the application of the INA bacteria, thereby resulting in an increased trehalase activity. Overall, the INA bacteria could act as effective heterogeneous ice nuclei which could lower the hardiness of E. extimalis to the cold and then freeze them to death in an extremely cold winter. Therefore, the control of insect pests with INA bacteria goes without doubt, in theory.202236292857
56100.9447Protein phosphatase AP2C1 negatively regulates basal resistance and defense responses to Pseudomonas syringae. Mitogen-activated protein kinases (MAPKs) mediate plant immune responses to pathogenic bacteria. However, less is known about the cell autonomous negative regulatory mechanism controlling basal plant immunity. We report the biological role of Arabidopsis thaliana MAPK phosphatase AP2C1 as a negative regulator of plant basal resistance and defense responses to Pseudomonas syringae. AP2C2, a closely related MAPK phosphatase, also negatively controls plant resistance. Loss of AP2C1 leads to enhanced pathogen-induced MAPK activities, increased callose deposition in response to pathogen-associated molecular patterns or to P. syringae pv. tomato (Pto) DC3000, and enhanced resistance to bacterial infection with Pto. We also reveal the impact of AP2C1 on the global transcriptional reprogramming of transcription factors during Pto infection. Importantly, ap2c1 plants show salicylic acid-independent transcriptional reprogramming of several defense genes and enhanced ethylene production in response to Pto. This study pinpoints the specificity of MAPK regulation by the different MAPK phosphatases AP2C1 and MKP1, which control the same MAPK substrates, nevertheless leading to different downstream events. We suggest that precise and specific control of defined MAPKs by MAPK phosphatases during plant challenge with pathogenic bacteria can strongly influence plant resistance.201728062592
7639110.9445Structural and Functional Changes of Groundwater Bacterial Community During Temperature and pH Disturbances. In this study, we report the characteristics of a microbial community in sampled groundwater and elucidate the effects of temperature and pH disturbances on bacterial structure and nitrogen-cycling functions. The predominant phyla of candidate OD1, candidate OP3, and Proteobacteria represented more than half of the total bacteria, which clearly manifested as a "low nucleic acid content (LNA) bacteria majority" type via flow cytometric fingerprint. The results showed that LNA bacteria were more tolerant to rapid changes in temperature and pH, compared to high nucleic acid content (HNA) bacteria. A continuous temperature increase test demonstrated that the LNA bacterial group was less competitive than the HNA bacterial group in terms of maintaining their cell intactness and growth potential. In contrast, the percentage of intact LNA bacteria was maintained at nearly 70% with pH decrease, despite a 50% decrease in total intact cells. Next-generation sequencing results revealed strong resistance and growth potential of phylum Proteobacteria when the temperature increased or the pH decreased in groundwater, especially for subclasses α-, β-, and γ-Proteobacteria. In addition, relative abundance of nitrogen-related functional genes by qPCR showed no difference in nitrifiers or denitrifiers within 0.45 μm-captured and 0.45 μm-filterable bacteria due to phylogenetic diversity. One exception was the monophyletic anammox bacteria that belong to the phylum Planctomycetes, which were mostly captured on a 0.45-μm filter. Furthermore, we showed that both temperature increase and pH decrease could enhance the denitrification potential, whereas the nitrification and anammox potentials were weakened.201930706112
541120.9445A Teleost Bactericidal Permeability-Increasing Protein Kills Gram-Negative Bacteria, Modulates Innate Immune Response, and Enhances Resistance against Bacterial and Viral Infection. Bactericidal/permeability-increasing protein (BPI) is an important factor of innate immunity that in mammals is known to take part in the clearance of invading Gram-negative bacteria. In teleost, the function of BPI is unknown. In the present work, we studied the function of tongue sole (Cynoglossus semilaevis) BPI, CsBPI. We found that CsBPI was produced extracellularly by peripheral blood leukocytes (PBL). Recombinant CsBPI (rCsBPI) was able to bind to a number of Gram-negative bacteria but not Gram-positive bacteria. Binding to bacteria led to bacterial death through membrane permeabilization and structural destruction, and the bound bacteria were more readily taken up by PBL. In vivo, rCsBPI augmented the expression of a wide arrange of genes involved in antibacterial and antiviral immunity. Furthermore, rCsBPI enhanced the resistance of tongue sole against bacterial as well as viral infection. These results indicate for the first time that a teleost BPI possesses immunoregulatory effect and plays a significant role in antibacterial and antiviral defense.201627105425
6002130.9445Comparative analysis of intestinal microbiota composition and transcriptome in diploid and triploid Carassius auratus. Polyploidy and the microbiome are crucial factors in how a host organism responds to disease. However, little is known about how triploidization and microbiome affect the immune response and disease resistance in the fish host. Therefore, this study aims to identify the relationship between intestinal microbiota composition, transcriptome changes, and disease resistance in triploid Carassius auratus (3nCC). In China's central Dongting lake water system, diploid (2nCC) and triploid Carassius auratus were collected, then 16S rRNA and mRNA sequencing were used to examine the microbes and gene expression in the intestines. 16S rRNA sequencing demonstrated that triploidization altered intestinal richness, as well as the diversity of commensal bacteria in 3nCC. In addition, the abundance of the genus Vibrio in 3nCC was increased compared to 2nCC (P < 0.05). Furthermore, differential expression analysis of 3nCC revealed profound up-regulation of 293 transcripts, while 324 were down-regulated. Several differentially expressed transcripts were related to the immune response pathway in 3nCC, including NLRP3, LY9, PNMA1, MR1, PELI1, NOTCH2, NFIL3, and NLRC4. Taken together, triploidization can alter bacteria composition and abundance, which can in turn result in changes in expression of genes. This study offers an opportunity for deciphering the molecular mechanism underlying disease resistance after triploidization.202336593453
48140.9444Priming of the Arabidopsis pattern-triggered immunity response upon infection by necrotrophic Pectobacterium carotovorum bacteria. Boosted responsiveness of plant cells to stress at the onset of pathogen- or chemically induced resistance is called priming. The chemical β-aminobutyric acid (BABA) enhances Arabidopsis thaliana resistance to hemibiotrophic bacteria through the priming of the salicylic acid (SA) defence response. Whether BABA increases Arabidopsis resistance to the necrotrophic bacterium Pectobacterium carotovorum ssp. carotovorum (Pcc) is not clear. In this work, we show that treatment with BABA protects Arabidopsis against the soft-rot pathogen Pcc. BABA did not prime the expression of the jasmonate/ethylene-responsive gene PLANT DEFENSIN 1.2 (PDF1.2), the up-regulation of which is usually associated with resistance to necrotrophic pathogens. Expression of the SA marker gene PATHOGENESIS RELATED 1 (PR1) on Pcc infection was primed by BABA treatment, but SA-defective mutants demonstrated a wild-type level of BABA-induced resistance against Pcc. BABA primed the expression of the pattern-triggered immunity (PTI)-responsive genes FLG22-INDUCED RECEPTOR-LIKE KINASE 1 (FRK1), ARABIDOPSIS NON-RACE SPECIFIC DISEASE RESISTANCE GENE (NDR1)/HAIRPIN-INDUCED GENE (HIN1)-LIKE 10 (NHL10) and CYTOCHROME P450, FAMILY 81 (CYP81F2) after inoculation with Pcc or after treatment with purified bacterial microbe-associated molecular patterns, such as flg22 or elf26. PTI-mediated callose deposition was also potentiated in BABA-treated Arabidopsis, and BABA boosted Arabidopsis stomatal immunity to Pcc. BABA treatment primed the PTI response in the SA-defective mutants SA induction deficient 2-1 (sid2-1) and phytoalexin deficient 4-1 (pad4-1). In addition, BABA priming was associated with open chromatin configurations in the promoter region of PTI marker genes. Our data indicate that BABA primes the PTI response upon necrotrophic bacterial infection and suggest a role for the PTI response in BABA-induced resistance.201322947164
41150.9443Rice WRKY13 regulates cross talk between abiotic and biotic stress signaling pathways by selective binding to different cis-elements. Plants use a complex signal transduction network to regulate their adaptation to the ever-changing environment. Rice (Oryza sativa) WRKY13 plays a vital role in the cross talk between abiotic and biotic stress signaling pathways by suppressing abiotic stress resistance and activating disease resistance. However, it is not clear how WRKY13 directly regulates this cross talk. Here, we show that WRKY13 is a transcriptional repressor. During the rice responses to drought stress and bacterial infection, WRKY13 selectively bound to certain site- and sequence-specific cis-elements on the promoters of SNAC1 (for STRESS RESPONSIVE NO APICAL MERISTEM, ARABIDOPSIS TRANSCRIPTION ACTIVATION FACTOR1/2, CUP-SHAPED COTYLEDON), the overexpression of which increases drought resistance, and WRKY45-1, the knockout of which increases both bacterial disease and drought resistance. WRKY13 also bound to two cis-elements of its native promoter to autoregulate the balance of its gene expression in different physiological activities. WRKY13 was induced in leaf vascular tissue, where bacteria proliferate, during infection, and in guard cells, where the transcriptional factor SNAC1 enhances drought resistance, during both bacterial infection and drought stress. These results suggest that WRKY13 regulates the antagonistic cross talk between drought and disease resistance pathways by directly suppressing SNAC1 and WRKY45-1 and autoregulating its own expression via site- and sequence-specific cis-elements on the promoters of these genes in vascular tissue where bacteria proliferate and guard cells where the transcriptional factor SNAC1 mediates drought resistance by promoting stomatal closure.201324130197
614160.9440Ehrlichia chaffeensis and Anaplasma phagocytophilum lack genes for lipid A biosynthesis and incorporate cholesterol for their survival. Ehrlichia chaffeensis and Anaplasma phagocytophilum are agents of human monocytic and granulocytic ehrlichioses, respectively. They are extremely sensitive to mechanical stress and are pleomorphic gram-negative bacteria. Membrane incorporation of cholesterol from the eukaryotic host is known to be essential for other fragile and pleomorphic bacteria and mycoplasmas that lack a cell wall. Thus, we tested whether cholesterol is required for E. chaffeensis and A. phagocytophilum. Using a freeze fracture technique and biochemical analysis, these bacteria were found to contain significant levels of membrane cholesterol. These bacteria lack genes for cholesterol biosynthesis or modification. However, host cell-free bacteria had the ability to take up directly exogenous cholesterol or NBD-cholesterol, a fluorescent cholesterol derivative. Treatment of the bacteria with cholesterol extraction reagent methyl-beta-cyclodextrin caused their ultrastructural changes. Furthermore, pretreatment of the bacteria with methyl-beta-cyclodextrin or NBD-cholesterol deprived these bacteria of the ability to infect leukocytes, thus killing these obligate intracellular bacteria. Analysis of E. chaffeensis and A. phagocytophilum genome sequences revealed that these bacteria lack all genes for the biosynthesis of lipid A and most genes for the biosynthesis of peptidoglycan, which confer structural strength to gram-negative bacteria. Taken together, these results suggest that human ehrlichiosis agents became cholesterol dependent due to the loss of these genes. As the first report of gram-negative bacteria incorporating cholesterol for survival, these findings offer insight into the unique nature of their parasitism and imply that cholesterol is important in the control of human ehrlichioses.200312933880
543170.9440OxyR2 Modulates OxyR1 Activity and Vibrio cholerae Oxidative Stress Response. Bacteria have developed capacities to deal with different stresses and adapt to different environmental niches. The human pathogen Vibrio cholerae, the causative agent of the severe diarrheal disease cholera, utilizes the transcriptional regulator OxyR to activate genes related to oxidative stress resistance, including peroxiredoxin PrxA, in response to hydrogen peroxide. In this study, we identified another OxyR homolog in V. cholerae, which we named OxyR2, and we renamed the previous OxyR OxyR1. We found that OxyR2 is required to activate its divergently transcribed gene ahpC, encoding an alkylhydroperoxide reductase, independently of H(2)O(2) A conserved cysteine residue in OxyR2 is critical for this function. Mutation of either oxyR2 or ahpC rendered V. cholerae more resistant to H(2)O(2) RNA sequencing analyses indicated that OxyR1-activated oxidative stress-resistant genes were highly expressed in oxyR2 mutants even in the absence of H(2)O(2) Further genetic analyses suggest that OxyR2-activated AhpC modulates OxyR1 activity by maintaining low intracellular concentrations of H(2)O(2) Furthermore, we showed that ΔoxyR2 and ΔahpC mutants were less fit when anaerobically grown bacteria were exposed to low levels of H(2)O(2) or incubated in seawater. These results suggest that OxyR2 and AhpC play important roles in the V. cholerae oxidative stress response.201728138024
9996180.9439In Situ Localization of Staphylococcus shinii and Staphylococcus succinus in Infected Rhipicephalus microplus Ticks: Implications for Biocontrol Strategies. Rhipicephalus microplus is a blood-sucking parasite that causes heavy infestations on cattle and is a vector for severe tick-borne diseases, such as anaplasmosis and babesiosis, and poses a significant threat to the cattle industry. Cattle ticks show increasing acaricide resistance, which creates an additional problem concerning the inefficient chemical control of tick populations in cattle-grazing areas, necessitating the exploration of alternative tick biocontrol methods. Our study aimed to demonstrate the acaropathogenic efficacy of two bacterial species during experimental infections on R. microplus. Our experimental data confirmed that S. shinii and S. succinus exhibited significant acaropathogenic properties against R. microplus, as demonstrated by the tracking of fluorescent-labeled bacteria within the engorged-tick body. Our experiments revealed that both bacterial species could infect the hemolymph, salivary glands, and vestibular vagina of the tick, inducing histological changes in the affected organs that may impair feeding as well as reproductive capabilities. Gené's organ infection was detected only in S. succinus. Our findings offer valuable insights for developing biocontrol strategies to manage Rhipicephalus microplus populations effectively.202439770285
8767190.9438Poly-γ-glutamic acid enhanced the drought resistance of maize by improving photosynthesis and affecting the rhizosphere microbial community. BACKGROUND: Compared with other abiotic stresses, drought stress causes serious crop yield reductions. Poly-γ-glutamic acid (γ-PGA), as an environmentally friendly biomacromolecule, plays an important role in plant growth and regulation. RESULTS: In this project, the effect of exogenous application of γ-PGA on drought tolerance of maize (Zea mays. L) and its mechanism were studied. Drought dramatically inhibited the growth and development of maize, but the exogenous application of γ-PGA significantly increased the dry weight of maize, the contents of ABA, soluble sugar, proline, and chlorophyll, and the photosynthetic rate under severe drought stress. RNA-seq data showed that γ-PGA may enhance drought resistance in maize by affecting the expression of ABA biosynthesis, signal transduction, and photosynthesis-related genes and other stress-responsive genes, which was also confirmed by RT-PCR and promoter motif analysis. In addition, diversity and structure analysis of the rhizosphere soil bacterial community demonstrated that γ-PGA enriched plant growth promoting bacteria such as Actinobacteria, Chloroflexi, Firmicutes, Alphaproteobacteria and Deltaproteobacteria. Moreover, γ-PGA significantly improved root development, urease activity and the ABA contents of maize rhizospheric soil under drought stress. This study emphasized the possibility of using γ-PGA to improve crop drought resistance and the soil environment under drought conditions and revealed its preliminary mechanism. CONCLUSIONS: Exogenous application of poly-γ-glutamic acid could significantly enhance the drought resistance of maize by improving photosynthesis, and root development and affecting the rhizosphere microbial community.202234979944