Synergistic effect of pyrene and heavy metals (Zn, Pb, and Cd) on phytoremediation potential of Medicago sativa L. (alfalfa) in multi-contaminated soil.

The environment in India is contaminated with polycyclic aromatic hydrocarbons (PAHs) due to the occurrence of large anthropogenic activities, i.e., fuel combustion, mineral roasting, and biomass burning. Hence, 13 toxic PAHs were detected: phenanthrene, anthracene, fluoranthene, pyrene, and benz(a) anthracene, ben-zo; (b) fluoranthene, benzo(k) fluoranthene, benzo(a) pyrene, benzo(ghi)perylene, dibenz (ah) anthracene, indeno1,2,3-(cd) pyrene, coronene and coronene in the environment (i.e., ambient particulate matter, road dust, sludge, and sewage) of the most industrialized area. Pollutants such as heavy metals and polycyclic aromatic hydrocarbons co-contaminate the soil and pose a significant hazard to the ecosystem because these pollutants are harmful to both humans and the environment. Phytoremediation is an economical plant-based natural approach for soil clean-up that has no negative impact on ecosystems. The aim of this study was to investigate the effects of pyrene (500 mg kg-1), Zn (150 mg kg-1), Pb (150 mg kg-1), and Cd (150 mg kg-1) alone and in combination on the phytoextraction efficiency of Medicago sativa growing in contaminated soil. Plant biomass, biochemical activities, translocation factors, accumulation of heavy metals, and pyrene removal were determined. After 60 days of planting, compared with those of the control plants, the growth parameters, biomass, and chlorophyll content of the M. sativa plants were significantly lower, and the reactive oxygen species activity, such as proline and polyphenol content and metallothionein protein content, was markedly greater in the pyrene and heavy metal-polluted soils. Furthermore, the combined toxicity of pyrene and all three metals on M. sativa growth and biochemical parameters was significantly greater than that of pyrene, Zn, Pb, or Cd alone, indicating the synergistic effect of pyrene and heavy metals on cytotoxicity. Pyrene stress increased Cd accumulation in M. sativa. After pyrene exposure alone or in combination with Zn-pyrene, a greater pyrene removal rate (85.5-81.44%) was observed than that in Pb-pyrene, Cd-pyrene, and Zn-Pb-Cd-pyrene polluted soils (62.78-71.27%), indicating that zinc can enhance the removal of pyrene from contaminated soil. The resulting hypotheses demonstrated that Medicago sativa can be used as a promising phytoremediation agent for co-contaminated soil.

Microbial-assisted phytodegradation for the amelioration of pyrene-contaminated soil using Pseudomonas aeruginosa and Aspergillus oryzae with alfalfa and sunflower.

Environmental pollution caused by polycyclic aromatic hydrocarbons (PAHs) jeopardizes nature. PAHs are the most toxic, mutagenic, and carcinogenic pollutants and their cleanup is important for the environment. In the current research, to assess and evaluate three remediation strategies for pyrene removal from the soil, a pot experiment was performed: (a) bioremediation with Pseudomonas aeruginosa and Aspergillus oryzae, (b) phytoremediation with sunflower (Helianthus annuus) and alfalfa (Medicago sativa L.) and (c) microbial-assisted phytoremediation for the treatment of pyrene (700 mg kg-1). Results depict that P. aeruginosa significantly promoted the growth and tolerance of taken plants and reduced pyrene concentration in soil. Compared with those planted in pyrene-contaminated soil without inoculation. The highest percentage of pyrene removal was observed in P. aeruginosa inoculated alfalfa (91%), alfalfa inoculated with A. oryzae (83.96%), and without inoculation (78.20%). Moreover, alfalfa planted in P. aeruginosa augmented soil had the highest dehydrogenase activity (37.83 µg TPF g-1 soil h-1), and fluorescein diacetate hydrolysis (91.67 µg fluorescein g-1 dry soil). DHA and FDA are the indicators of bioaugmentation influence on the indigenous microbial activity of contaminated soil. As a result of the findings, the rhizospheric association of plants and microbes is beneficial for pyrene removal. Therefore, P. aeruginosa-assisted phytodegradation might be a more successful remediation technique for pyrene-contaminated soil than bioremediation and phytodegradation solely.

Comparative analysis of remediation efficiency and ultrastructural translocalization of polycyclic aromatic hydrocarbons in Medicago sativa, Helianthus annuus, and Tagetes erecta.

Polycyclic aromatic hydrocarbons (PAHs) are semi-volatile anthropogenic contaminants that can damage soil fertility and threaten the environment due to their hazardous effects on various ecological parameters. The experimental objective was divided into two parts because PAHs are always present in mixtures. The toxicity of anthracene, phenanthrene, pyrene, and fluoranthene was examined and investigated the potential of three phytoremediator plants species viz Tagetes erecta, Helianthus annuus, and Medicago sativa for remediation and translocation of individual PAH. PAHs were shown to have inhibitory or stimulating effects on growth, antioxidant properties, and impact on the structure of plant cells. The result showed that M. sativa significantly enhances the removal rate of PAHs in the soil. The dissipation rate reached 96.2% in M. sativa planted soil, followed by H. annuus and T. erecta. Among the plant species, M. sativa exhibited the highest root and shoot concentrations (314.37 and 169.55 mg kg-1), while the lowest concentration was 187.56 and 76.60 mg kg-1 in T. erecta. SEM-EDX and fluorescence micrographs confirmed that pyrene altered plant tissue's ultrastructure and cell viability and was found to be the most toxic and resistant. M. sativa was proven to be the most effective plant for the mitigation of PAHs.

The novelty of our work situates phytoremediation into a practical viewpoint as to whether the process can be achieved within a measurable amount of time. In conclusion, Medicago sativa behaved as the more tolerant plant species in PAH-contaminated soil. While to the best of our knowledge, researchers have yet to study single contamination of PAH together, especially for phenanthrene and pyrene. We hope our study is fundamental and will help assess M. sativa as a potential phytoremediator plant for hydrocarbon-contaminated soil. Furthermore, this work is novel because the plant can remediate PAHs from industrial soil and agricultural fields. The harvested plant material can later be used for various purposes, such as biodegradable paper production. The higher dissipation of hydrocarbons measured in soil cultivated with M. sativa may be related to a large amount of soil bacteria stimulated explicitly by the M. sativa fibrous root system. Further studies are in progress to evaluate the possible degradation of PAH using microorganisms.

Isolation, purification and characterization of quercetin from Cucumis sativus peels; its antimicrobial, antioxidant and cytotoxicity evaluations.

The peels of C.sativus are produced in large quantities in food processing industries and as kitchen-waste, resulting into tremendous loss of valuable bioactive components. Considering this, the flavanoids from C.sativus peels (CSP) were isolated and characterized by the column chromatography, high-performance thin-layer chromatography (HPTLC), Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR) methods. The antioxidant and antibacterial activity of CSP extract against Escherichia coli, Streptococcus mutans and Pseudomonas aeruginosa was assessed. Scanning electron microscopy (SEM) was also used to investigate the killing efficacy of CSP extract against selected bacterial strains. Cytotoxic activity of extract was analyzed on L929 (connective tissue, Mouse, Mus Muscular) cell lines to check their viability. According to the results, total flavanoid content in CSP extract was found as 55.3 ± 1.154 µg/g QE and the chromatographic and spectral data of the isolated compound was elucidated as quercetin-a flavanoid. The CSP extract has also found to give significant antioxidant activity for both DPPH (2, 2-diphenyl-1-picrylhydrazyl) and FRAP (ferric reducing antioxidant power) assay. The CSP extract was found to inhibit growth of E. coli, P. aeruginosa and S. mutans by forming inhibitory zones of 11.36 ± 0.47, 6.7 ± 0.36 mm and 10.16 ± 0.11 mm, respectively. The SEM results also confirm the rupturing of cells or biofilms of bacterial cells as compare to control strains. Additionally, CSP extract was found to not inhibit the proliferation of L929 cells and more than 90% viability of cells was achieved. The present finding highlights the phytochemical profile and therapeutic applications of C.sativus peels.

Value added bioactive compounds from fruits & vegetables waste for assessing their antimicrobial activity.

Since ancient time, plants and there parts have been used widely against dreadful pathogens due to ability of killing microbes. Waste from fruits and vegetables are pulling in more interest in exploration due to their therapeutic properties such as anti-pathogenic activity. In the present study antimicrobial and cytotoxicity properties of herbal combination prepared from peels of Allium cepa, Cucumis sativus, Citrus reticulata, and Mangifera indica were investigated. The herbal combination was tested for broad spectrum antimicrobial activity against Streptococcus mutans, Bacillus licheniformis, Lactobacillus plantarum, Escherichia coli, Pseudomonas aeruginosa, and Citrobacter freundii. The presence of phytochemical markers such as phenolics and flavanoids were also investigated. The results revealed that the herbal combination exhibited antimicrobial activity against S. mutans, B. licheniformis, L. plantarum, E. coli and moderate against P. aeruginosa and C. freundii. The presence of phenolics (798 ± 1.52 µg/g) and flavanoids (355.3 ± 2.081 µg/g) was also detected. Also, the herbal combination contains flavanoids such as quercetin and rutin was confirmed with the help of column chromatography, high-performance liquid chromatography (HPLC), fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR) analysis. The herbal combination helps in the proliferation of L929 cells without affecting their viability was confirmed by MTT assay. The results of the present research suggests the possibility to use herbal combination as source for plausible antibacterial agent which could be isolated and used as a lead candidate for the development of antibacterial drug that help to limit or stop infectious illnesses caused by different pathogenic microbes.

Phytoaccumulation of zinc from contaminated soil using ornamental plants species Helianthus annuus L. and Tagetes erecta L.

Intensive research on hyperaccumulator plant species provides an alternative method to cleanup heavy metal contaminated sites using these plants. Helianthus annuus and Tagetes erecta are suitable hyperaccumulator plant species for removing zinc (Zn) from contaminated soil because of their high phytoremediation effectiveness. The present study focused on to evaluate comparative efficacy of Zn accumulation using H. annuus and T. erecta. Plantlets were exposed to different Zn concentrations (10, 50, 100, 300, and 500 mg kg-1) for 20, 40, and 60 days while changes in morphological, biochemical, and enzyme activity markers were evaluated. The concentration of Zn in various plant parts was determined using an atomic absorption spectrophotometer (AAS). After 60 days H. annuus showed greatest accumulation of Zn in the root and shoot (216.7 and 109.5 mg kg-1), whereas the Zn accumulation T. erecta (209.5 and 97.84 mg kg-1) was found comparatively less in the root and shoot. The result showed increased polyphenol and proline concentrations with increasing Zn concentrations which were maximal in H. annuus 6.642 mg g-1 and 25.474 µmol g-1, respectively. At 60 days, APX (4.145 mM mg-1), CAT (2.558 mM mg-1), and GR (52.23 mM mg-1) antioxidant enzymatic activities were observed with higher concentrations. Analysis of ultrastructure confirmed Zn transport and localization in root and shoot tissues examined through FESEM-EDX, Fluorescence microscopy, and optical microscopy. The present research findings concluded with the high amount of removal of Zn from contaminated soil using H. annuus and T. erecta for ecofriendly approach to soil cleanup followed by sustainable agriculture.

Our research work focused on the removal of zinc from the contaminated soil by phytoremediation using ornamental plants species Helianthus annuus and Tagetes erecta. Our research findings through detailed microscopic observation, antioxidant analysis, and biochemical evaluation have proven that Helianthus annuus L. have a better capability for Zn mitigation in the contaminated site as compared to Tagetes erecta. As an outcome of this research, we authentically suggest for use of H. annuus as a good accumulator of Zn compared to T. erecta.

Non-viral precision T cell receptor replacement for personalized cell therapy.

T cell receptors (TCRs) enable T cells to specifically recognize mutations in cancer cells1-3. Here we developed a clinical-grade approach based on CRISPR-Cas9 non-viral precision genome-editing to simultaneously knockout the two endogenous TCR genes TRAC (which encodes TCRα) and TRBC (which encodes TCRß). We also inserted into the TRAC locus two chains of a neoantigen-specific TCR (neoTCR) isolated from circulating T cells of patients. The neoTCRs were isolated using a personalized library of soluble predicted neoantigen-HLA capture reagents. Sixteen patients with different refractory solid cancers received up to three distinct neoTCR transgenic cell products. Each product expressed a patient-specific neoTCR and was administered in a cell-dose-escalation, first-in-human phase I clinical trial ( NCT03970382 ). One patient had grade 1 cytokine release syndrome and one patient had grade 3 encephalitis. All participants had the expected side effects from the lymphodepleting chemotherapy. Five patients had stable disease and the other eleven had disease progression as the best response on the therapy. neoTCR transgenic T cells were detected in tumour biopsy samples after infusion at frequencies higher than the native TCRs before infusion. This study demonstrates the feasibility of isolating and cloning multiple TCRs that recognize mutational neoantigens. Moreover, simultaneous knockout of the endogenous TCR and knock-in of neoTCRs using single-step, non-viral precision genome-editing are achieved. The manufacture of neoTCR engineered T cells at clinical grade, the safety of infusing up to three gene-edited neoTCR T cell products and the ability of the transgenic T cells to traffic to the tumours of patients are also demonstrated.

Comparative evaluation of cadmium phytoremediation potential of five varieties of Helianthus annuus L.

Helianthus annuus is a potential metal accumulator plant, which can find application in cadmium (Cd) phytoremediation and provide economic gains in terms of oil yield. This study is focused on Cd accumulation analysis, physiological and biochemical responses of five varieties of H. annuus (DRSF-108, DRSF-113, LSFH-171, Phule Bhaskar and KBSH-44). Plantlets of all varieties were treated with various Cd concentrations (10, 50, 100, 300 and 500 mg kg-1) for 20, 40 and 60 days. DRSF-108 showed the maximum total Cd accumulation (430.52 mg kg-1) in whole plant while minimum accumulation was observed in KBSH-44 (150.66 mg kg-1) at 500 mg kg-1 Cd after 60 days. The highest level of proline and polyphenol in DRSF-108 were 27.206 µmol g-1 fw and 6.86 mg g-1 fw, respectively. Antioxidant enzymes (catalase, ascorbate peroxidase and glutathione reductase) also showed increased activity in response to Cd treatment. SEM-EDX analysis of potential accumulator genotype, DRSF-108, showed the distribution of intracellular Cd into plant tissues. Therefore, it is concluded that among five varieties, DRSF-108 was the most potential Cd accumulator and had a higher capacity for Cd tolerance compared to other varieties. Our findings may allow us to extend variety DRSF-108 for sustainable farming and Cd remediation.

Phytoremediation of environmental contaminants is a promising strategy, however, the success depends on the use of suitable plants. Helianthus annuus is a good phytoremediator plant and the use of most promising genotype is desirable. This work evaluated five genotypes of H. annuus for cadmium accumulation and identified the best variety, DRSF-108 that can be used for cadmium remediation. The work shall pave way for field application of sunflower plants in cadmium remediation.

Silica nanoparticles as novel sustainable approach for plant growth and crop protection.

Agriculture crops encounter several biotic and abiotic stresses, including pests, diseases, nutritional deficits, and climate change, which necessitate the development of new agricultural technologies. By developing nano-based fertilizers, insecticides and herbicides, and early disease diagnostics, nanotechnology may help to increase agricultural crop quality and production. The application of silica nanoparticles (SiNPs) may be the solution for increasing the yield to combat the agriculture crisis in the near future. SiNPs have unique physiological properties, such as large surface area, aggregation, reactivity, penetrating ability, size, and structure, which enable them to penetrate plants and regulate their metabolic processes. Pesticide delivery, enhanced nutrition supply, disease management, and higher photosynthetic efficiency and germination rate are all attributed to SiNPs deposition on plant tissue surfaces. SiNPs have been demonstrated to be non-toxic in nature, making them suitable for usage in agriculture. In this regard, the current work provides the most important and contemporary applications of SiNPs in agriculture as well as biogenic and non-biogenic synthetic techniques. As a result, this review summarizes the literature on SiNPs and explores the use of SiNPs in a variety of agricultural disciplines.

Application of agro-waste-mediated silica nanoparticles to sustainable agriculture.

Use of green agronomic techniques for plant development and crop protection is essential for environmental sustainability. The current research investigates a more efficient and long-term technique of manufacturing silica nanoparticles (SiO2 NPs) from agricultural waste (sugarcane bagasse and corn cob). SiO2 NPs were synthesized by calcinations of waste residues in muffle furnace with varying temperatures (400-1000 °C)/2 h in the present of static air. Field emission scanning electron microscopy (FESEM), Fourier transmission infrared spectroscopy (FTIR), X-ray diffraction (XRD), and energy dispersive X-ray spectroscopy (EDX) were used to characterize SiO2 NPs and assessed for their antifungal activity simultaneously investigated the effects of various concentrations of produced SiO2 NPs on Eruca sativa (E. sativa) physiological and biochemical. With SiO2 NPs treatment at 1000 µg L-1 concentration, the seed germination rate was found to be up to 95.5%, and growth characteristics were enhanced compared to control. Accordingly, the ones treated with SiO2 NPs grew better than the control ones. The treatment of plant with SiO2 NPs (500 µg L-1) increased the protein content by 14.8 mg g-1, and chlorophyll level was also increased by 4.08 mg g-1 in leaves compared to untreated plant. Disc diffusion experiment was conducted to test the efficiency of SiO2 NPs against Fusarium oxysporum and Aspergillus niger for antifungal activities. Highest mycelia growth inhibition was obtained with 73.42% and 58.92% for F. oxysporum and A. niger, respectively. The result shows that the SiO2 NPs have a favorable effect on E. sativa growth and germination, enhancing plant production which helps to improve the sustainable agriculture farming and acting as a possible antifungal agent against plant pathogenic fungi.

A convolutional neural network architecture for the recognition of cutaneous manifestations of COVID-19.

During the COVID-19 pandemic, dermatologists reported an array of different cutaneous manifestations of the disease. It is challenging to discriminate COVID-19-related cutaneous manifestations from other closely resembling skin lesions. The aim of this study was to generate and evaluate a novel CNN (Convolutional Neural Network) ensemble architecture for detection of COVID-19-associated skin lesions from clinical images. An ensemble model of three different CNN-based algorithms was trained with clinical images of skin lesions from confirmed COVID-19 positive patients, healthy controls as well as 18 other common skin conditions, which included close mimics of COVID-19 skin lesions such as urticaria, varicella, pityriasis rosea, herpes zoster, bullous pemphigoid and psoriasis. The multi-class model demonstrated an overall top-1 accuracy of 86.7% for all 20 diseases. The sensitivity and specificity of COVID-19-rash detection were found to be 84.2 ± 5.1% and 99.5 ± 0.2%, respectively. The positive predictive value, NPV and area under curve values for COVID-19-rash were 88.0 ± 5.6%, 99.4 ± 0.2% and 0.97 ± 0.25, respectively. The binary classifier had a mean sensitivity, specificity and accuracy of 76.81 ± 6.25%, 99.77 ± 0.14% and 98.91 ± 0.17%, respectively for COVID-19 rash. The model was robust in detection of all skin lesions on both white and skin of color, although only a few images of COVID-19-associated skin lesions from skin of color were available. To our best knowledge, this is the first machine learning-based study for automated detection of COVID-19 based on skin images and may provide a useful decision support tool for physicians to optimize contact-free COVID-19 triage, differential diagnosis of skin lesions and patient care.

Phytoremediation efficiency of Helianthus annuus L. for reclamation of heavy metals-contaminated industrial soil.

Soil pollution is rapidly increasing due to industrialization and urbanization. Heavy metal pollution raised concern because of its possible impact on plants and humans. Helianthus annuus L. is a good hyperaccumulator plant, used for the removal of heavy metals because of its phytoremediation efficiency. In the present study, we cultivated H. annuus plants in industrial contaminated soil collected from various industries like plastic, paper, dye, and textile of different areas of Jaipur (Rajasthan), Kashipur, Jaspur, and Bajpur (Uttrakhand), India. Plantlets accumulated a different range of Pb, Cd, Zn, Cu, Fe, and As (0.62-158.29, 0.8-59.6, 0.81-166.5, 0.09-101.89, 2.06-53.25, and 0.002-2.55 mg kg-1, respectively) from the industrial soil samples. Heavy metal analysis was done using flame and graphite furnace atomic absorption spectrophotometer. The effects of heavy metals were analyzed by studying the morphological, biochemical, and antioxidant enzymatic analysis. The results revealed that industrial contaminated soil had a significant impeding effect on the plantlets of H. annuus as noticed by the reduction in growth parameters compared to the standard. Furthermore, one-way ANOVA and principal component analysis (PCA) were applied for statistical analysis and to determine the correlation between plant growth parameters, removed heavy metals, and biochemical. Thus, this study will be helpful for the decontamination of highly affected industrial soil.

Genetic and biochemical variability among Moringa oleifera Lam. accessions collected from different agro-ecological zones.

Genomic DNA polymorphism and variation in biologically active components of Moringa oleifera were investigated by two different techniques: RAPD-PCR and HPLC analysis. The concentrations of phenolic compounds (cinnamic, caffeic, ferulic, and coumaric acids) and the content of flavonoids (rutin) were quantified by HPLC analysis. Among 20 RAPD primers, 13 were selected to generate polymorphic amplicons producing an average of 5028 bands, of which 83.7% were found to be polymorphic among 57 accessions of M. oleifera (MO 1 to MO 57) and one outgroup (ACB 58) from Banasthali region, India. In total, 57 accessions were clustered into five major groups within the dendrogram. The results of this analysis were further confirmed by principal coordinate analysis (PCoA). There was also high diversity in the concentration of active compounds in the collected samples as revealed by HPLC analysis. The data revealed that the content of polyphenolic compounds varied between 0.06 (sample KVKB) and 210.5 mg/kg (sample BG). The results suggest that there is a strong correlation between phytochemical variables and DNA polymorphism. The study concludes that the results of the genetic, morphological, and phytochemical diversity could be used to select the best accessions of M. oleifera for agricultural cultivation and breeding.

Identifying Dental Anxiety in Children's Drawings and correlating It with Frankl's Behavior Rating Scale.

AIM: To develop a simple method to assess the level of anxiety by using children's drawings and correlating them with Frankl's behavior rating scale. MATERIALS AND METHODS: A total of 178 patients aged of 3 to 14 years were handed out two-page forms which contained three sections on coloring and drawing, along with general information, and Frankl's behavior rating scale for the visit. The three types of drawing exercises given to the patients were geometric copy drawings, coloring a nonthreatening figure, and an empty sheet for freehand drawing. RESULTS: Out of 178 patients, 60 showed definitely positive behavior, 73 exhibited positive behavior, 37 showed negative behavior, and 8 were definitely negative on Frankl's behavior rating scale; 133 children had none or, 1 stress marker and 45 exhibited 2 or 3 stress markers in their drawings. Chi-square (χ2) analysis was done with a 2 × 2 contingency table. Observed χ2 value was 46.166, which at 1 degree of freedom was much greater than that at 0.995 percentile. Therefore, the result was highly significant. CONCLUSION: Children requiring specialized behavioral techniques can be identified by the presence of stress markers in their drawings. This nonverbal activity by itself can have an overall positive effect on the behavior displayed in the dental clinic. HOW TO CITE THIS ARTICLE: Mathur J, Diwanji A, Sarvaiya B, Sharma D. Identifying Dental Anxiety in Children's Drawings and correlating It with Frankl's Behavior Rating Scale. Int J Clin Pediatr Dent 2017;10(1):24-28.

Antimicrobial peptides activate the Vibrio cholerae sigmaE regulon through an OmpU-dependent signalling pathway.

Vibrio cholerae, an enteric pathogen, is subject to assault by several membrane-acting, host gut-derived antimicrobial peptides (AP). We previously found that a major V. cholerae outer membrane protein, OmpU, confers resistance to polymyxin B and to a bioactive peptide (P2) derived from the human bactericidal/permeability-increasing protein. Here, we report that the alternative sigma factor sigma(E) also plays a critical role in determining V. cholerae resistance to AP and that OmpU and sigma(E) lie in the same pathway. In fact, we found that OmpU is a key determinant of basal sigma(E) expression. We also found that sublethal AP exposure activates sigma(E) and the sigma(E)-mediated periplasmic stress response. sigma(E) is not activated by P2 in V. cholerae cells lacking OmpU or DegS, a periplasmic protease that controls sigma(E) activity. The lack of AP-elicited sigma(E) activation in a strain harbouring a point mutation in OmpU's putative DegS-binding residues provides support for a link between OmpU and DegS-mediated activation of sigma(E). We propose that AP-induced membrane perturbations change the conformation of OmpU to trigger a DegS-dependent sigma(E)-activating cascade. Thus, OmpU appears to act as a sensor component in a signal transduction pathway.

The Vibrio cholerae ToxR-regulated porin OmpU confers resistance to antimicrobial peptides.

BPI (bactericidal/permeability-increasing) is a potent antimicrobial protein that was recently reported to be expressed as a surface protein on human gastrointestinal tract epithelial cells. In this study, we investigated the resistance of Vibrio cholerae, a small-bowel pathogen that causes cholera, to a BPI-derived peptide, P2. Unlike in Escherichia coli and Salmonella enterica serovar Typhimurium, resistance to P2 in V. cholerae was not dependent on the BipA GTPase. Instead, we found that ToxR, the master regulator of V. cholerae pathogenicity, controlled resistance to P2 by regulating the production of the outer membrane protein OmpU. Both toxR and ompU mutants were at least 100-fold more sensitive to P2 than were wild-type cells. OmpU also conferred resistance to polymyxin B sulfate, suggesting that this porin may impart resistance to cationic antibacterial proteins via a common mechanism. Studies of stationary-phase cells revealed that the ToxR-repressed porin OmpT may also contribute to P2 resistance. Finally, although the mechanism of porin-mediated resistance to antimicrobial peptides remains elusive, our data suggest that the BPI peptide sensitivity of OmpU-deficient V. cholerae is not attributable to a generally defective outer membrane.