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SHIN, Hwain, Kazuya OKADA, John C. WILKINSON, Katherine M. SOLOMON, Colin S. DUCKETT, John C. REED e Guy S. SALVESEN. "Identification of ubiquitination sites on the X-linked inhibitor of apoptosis protein". Biochemical Journal 373, n.º 3 (1 de agosto de 2003): 965–71. http://dx.doi.org/10.1042/bj20030583.
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The execution phase of apoptosis is under the control of members of the inhibitor of apoptosis (IAP) family of zinc finger proteins. Several of these proteins contain a C-terminal RING (really interesting new gene) domain that has been postulated to regulate ubiquitination of themselves or their target proteins, thereby modulating thresholds for apoptosis. We demonstrate that the auto-ubiquitination sites of the X-linked IAP (XIAP) are Lys322 and Lys328, located in the third baculovirus IAP repeat domain of the protein. Modification of these sites to arginine dramatically reduces ubiquitination of XIAP, but has no measurable effect on the ability of ectopically expressed IAP to rescue cells from two independent apoptotic inducers. Our data firmly locate the auto-ubiquitination sites, and raise doubts regarding the importance of this event as a mechanism for regulating the levels of XIAP.
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Gonzalez-Chapa, Jorge Armando, Marina Barguil Macêdo e Christian Lood. "The Emerging Role of Mitochondrial Dysfunction in the Pathogenesis of Idiopathic Inflammatory Myopathies". Rambam Maimonides Medical Journal 14, n.º 2 (30 de abril de 2023): e0006. http://dx.doi.org/10.5041/rmmj.10493.
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Increasing evidence points towards mitochondria as crucial players in the initiation and progression of auto-immune and degenerative disorders, to which impaired cell metabolism is but a facet of the subjacent etiopathogenesis. This review aims to introduce the reader to essential concepts of mitochondrial abnormalities in idiopathic inflammatory myopathy (IIM), underscoring inclusion-body myositis and dermatomyositis. Far surpassing the initial simplistic view of being responsible for energy generation, mitochondria have gathered attention regarding their role in inflammatory processes, being able to fuel autoimmunity, as shown by the presence of anti-mitochondrial antibodies (AMAs) in up to 10% of IIM patients. As cellular respiration takes place, mitochondrial metabolites might help to shape the pro-inflammatory milieu in affected muscle, beyond generating reactive oxygen species, which are well-recognized inducers of damage-associated molecular patterns. A series of mitochondrial components might facilitate the sterile activation of pro-inflammatory cells and the production of several cytokines responsible for enhancing auto-immune responses. Marked variation in the mitochondrial genome has also been reported in IIM patients. As such, we summarize key historical and recent advances linking aberrations and instabilities of mitochondrial DNA to impaired muscle function. Besides discussing mitochondrial dysfunction as an essential part of IIM development, we also highlight possible associations between presence of AMAs and a particular phenotype of IIM, with its own characteristic clinical and radiological pattern. Finally, we present promising treatment approaches targeting mitochondria, while briefly discussing experimental models for gaining deeper insight into the disease process, and ultimately leading to novel drug development.
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TANAKA, Motoyuki, Stephan R. Krutzik, Peter A. Sieling, Thomas H. Rea e Robert L. Modlin. "Fcγ receptor activation triggers monocytes to differentiate into CD1b+ immature dendritic cells (B138)". Journal of Immunology 178, n.º 1_Supplement (1 de abril de 2007): LB29. http://dx.doi.org/10.4049/jimmunol.178.supp.b138.
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Abstract Antibodies are potent inducers of inflammation and Fcγ receptors (FcγRs) are considered as important immune-regulators linked to infection immunity, cancer immunity and auto-immunity. We previously reported that CD1b+ dendritic cells (DC) are differentially distributed in leprosy lesions and contribute to the in pathophysiology of the polarized clinical spectrum of the disease. Here we demonstrate that activation of FcγRs on human blood monocytes triggers monocyte differentiation into CD1b+ cells. The CD1b+ population increased in a dose-dependent manner, and the differentiation was blocked by the addition of an anti-CD64 monoclonal antibody. Furthermore, Fcγ receptor ligation triggered transcription of GM-CSF mRNA as measured by real time PCR and CD1b+ cell differentiation was suppressed by the addition of an anti-GM-CSF antibody. Finally, FcγR-induced CD1b+ cells exhibited an immature dendritic cell (DC)-like phenotype. These findings predict that the stimulation of FcγRs induces GM-CSF production that in turn triggers monocyte differentiation into a CD1b+ immature dendritic cell population. In conclusion, these results provide insight into the cross-talk between the humoral and innate immune response as well as new strategies for therapeutic intervention in infectious diseases and autoimmune diseases.
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Morgan-Sagastume, Fernando, Nico Boon, Sofie Dobbelaere, Tom Defoirdt e Willy Verstraete. "Production of acylated homoserine lactones byAeromonasandPseudomonasstrains isolated from municipal activated sludge". Canadian Journal of Microbiology 51, n.º 11 (1 de novembro de 2005): 924–33. http://dx.doi.org/10.1139/w05-077.
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Up to now, the production and role of N-acyl homoserine lactones (AHLs) in activated sludge have been poorly understood. In this study, cross-feeding assays with the reporter strains Agrobacterium tumefaciens NTL4 and Chromobacterium violaceum CV026 were used to investigate AHL signal production by municipal activated sludge samples. AHL signal production was consistently detected from municipal activated sludge when different samples were incubated on nutrient media. From one municipal activated sludge sample, 10 strains producing AHL-like auto inducers were isolated by an overlay technique. 16S rDNA-based phylogenetic analysis showed that eight of the isolates belonged to Aeromonas spp. and two to Pseudomonas spp. Box-PCR indicated that six of these Aeromonas isolates were different strains and the two Pseudomonas strains were identical. The production of AHL or AHL-like compounds by these strains was confirmed by thin layer chromatography and biosensor overlays. The six different Aeromonas strains were found to produce the same set of AHLs, including N-hexanoyl-L-homoserine lactone. These results may indicate the possible presence of AHLs in municipal activated sludge. The potential roles of AHL in this eco system are briefly discussed.Key words: municipal activated sludge, acylated homoserine lactones, Aeromonas spp., bioaggregates, Pseudomonas spp., AHL biosensors.
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Haniyya, Haniyya, Dini Achnafani, Maria Ulfah, Niknik Nurhayati e Is Helianti. "The utilization of auto-inducible Plyb promoter and media optimation for cell density-dependent expression of recombinant xylanase in Bacillus subtilis DB104". Microbiology Indonesia 14, n.º 1 (1 de julho de 2020): 2. http://dx.doi.org/10.5454/mi.14.1.2.
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Strong promoters are one of the fundamental aspects to increase the level of gene expression, and one of approach to improve the recombinant enzyme productivity so that the efficiency of production cost for enzyme production in industrial scale can be reached. Here we assessed the application of a cell density-dependent promoter and media optimation to promote cell growth and protein expression of Bacillus subtilis without excess usage of inducers. An auto-inducible Pylb promoter that is potential to provide inducer-free enzyme production was cloned and introduced into xylanase recombinant system in B. subtilis DB104 by PCR cloning and protoplast transformation. A 200 bp target gene was successfully inserted in between xynCM1 ORF -coding for B. halodurans CM1 xylanase- and its native promoter sequence at the upstream region. The disruption of the native promoter was intended to replace the native promoter with Pylb. Recombinant xylanase gene under Pylb was successfully expressed in B. subtilis DB104 and the enzyme was produced at stationary phase. Different media with various concentrations of glucose and nitrogen were used to optimize recombinant xylanase expression. It achieved a higher level of xylanase expression compared to wild-type and recombinant xylanase with native promoter B. subtilis in media containing a 2-fold recipe of LB media thus leads to increase cell density and xylanase expression (81.461 U mL-1).
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Hetta, Helal F., Yasmin N. Ramadan, Zainab I. Rashed, Ahmad A. Alharbi, Shomokh Alsharef, Tala T. Alkindy, Alanoud Alkhamali, Abdullah S. Albalawi, Basem Battah e Matthew G. Donadu. "Quorum Sensing Inhibitors: An Alternative Strategy to Win the Battle against Multidrug-Resistant (MDR) Bacteria". Molecules 29, n.º 15 (24 de julho de 2024): 3466. http://dx.doi.org/10.3390/molecules29153466.
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Antibiotic resistance is a major problem and a major global health concern. In total, there are 16 million deaths yearly from infectious diseases, and at least 65% of infectious diseases are caused by microbial communities that proliferate through the formation of biofilms. Antibiotic overuse has resulted in the evolution of multidrug-resistant (MDR) microbial strains. As a result, there is now much more interest in non-antibiotic therapies for bacterial infections. Among these revolutionary, non-traditional medications is quorum sensing inhibitors (QSIs). Bacterial cell-to-cell communication is known as quorum sensing (QS), and it is mediated by tiny diffusible signaling molecules known as autoinducers (AIs). QS is dependent on the density of the bacterial population. QS is used by Gram-negative and Gram-positive bacteria to control a wide range of processes; in both scenarios, QS entails the synthesis, identification, and reaction to signaling chemicals, also known as auto-inducers. Since the usual processes regulated by QS are the expression of virulence factors and the creation of biofilms, QS is being investigated as an alternative solution to antibiotic resistance. Consequently, the use of QS-inhibiting agents, such as QSIs and quorum quenching (QQ) enzymes, to interfere with QS seems like a good strategy to prevent bacterial infections. This review sheds light on QS inhibition strategy and mechanisms and discusses how using this approach can aid in winning the battle against resistant bacteria.
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Naik, Varsha, e Girish Mahajan. "Quorum Sensing: A Non-conventional Target for Antibiotic Discovery". Natural Product Communications 8, n.º 10 (outubro de 2013): 1934578X1300801. http://dx.doi.org/10.1177/1934578x1300801030.
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Quorum sensing (QS) is known to regulate different functions viz. pathogenesis, biofilm formation, and host colonization, along with other functions by regulating bacterial virulence determinants. Therefore, QS is deemed to be an interesting target to modulate pathogenesis. Also, there have been global reports of continuous emergence of antibiotic-resistant microbes; hence, an alternative treatment that compliments antibiotic activity is highly desirable. One such approach is to look for QS inhibitors, which can quench the virulence phenotypes exerted by pathogenic bacteria and compliment antibiotic treatment. In the present study, Pseudomonas aeruginosa strain was used as the model organism which produces three pigments viz. pyocyanin, pyoverdin and pyorubin. Pyocyanin synthesis is reported to be QS dependent and is one of the virulence factors of P. aeruginosa. Hence, we envisage inhibition of pyocyanin pigment would indicate QS inhibition (QSI). Auto-inducers like N-(3-oxododecanoyl)-L-homoserine lactone (OdDHL/3-oxo-C12-HSL) and N-butyryl-L- homoserine lactone (BHL/C4-HSL) were used to enhance the pyocyanin pigment production by the model strain at different doses and time points. BHL, at 25 μM was found to be a better inducer of pyocyanin. Tannic acid (TA) was tested to suppress this pigment synthesis and it was found to be effective when assessed at different time points. About 5.12 mg/mL TA was found to be the optimum concentration at which pyocyanin was inhibited by 77.3%. Thus, we confirm that TA can be used as a QSI, either in its purest form or in the crude form found in various plant species, and could be considered for development to compliment antibiotic therapy.
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Mujawdiya, Pavan K., e Suman Kapur. "Modulation of Gut Microbiota through Dietary Phytochemicals as a Novel Anti-infective Strategy". Current Drug Discovery Technologies 17, n.º 4 (8 de setembro de 2020): 498–506. http://dx.doi.org/10.2174/1570163816666191107124214.
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: Quorum Sensing (QS) is a phenomenon in which bacterial cells communicate with each other with the help of several low molecular weight compounds. QS is largely dependent on population density, and it triggers when the concentration of quorum sensing molecules accumulate in the environment and crosses a particular threshold. Once a certain population density is achieved and the concentration of molecules crosses a threshold, the bacterial cells show a collective behavior in response to various chemical stimuli referred to as “auto-inducers”. The QS signaling is crucial for several phenotypic characteristics responsible for bacterial survival such as motility, virulence, and biofilm formation. Biofilm formation is also responsible for making bacterial cells resistant to antibiotics. : The human gut is home to trillions of bacterial cells collectively called “gut microbiota” or “gut microbes”. Gut microbes are a consortium of more than 15,000 bacterial species and play a very crucial role in several body functions such as metabolism, development and maturation of the immune system, and the synthesis of several essential vitamins. Due to its critical role in shaping human survival and its modulating impact on body metabolisms, the gut microbial community has been referred to as “the forgotten organ” by O`Hara et al. (2006) [1]. Several studies have demonstrated that chemical interaction between the members of bacterial cells in the gut is responsible for shaping the overall microbial community. : Recent advances in phytochemical research have generated a lot of interest in finding new, effective, and safer alternatives to modern chemical-based medicines. In the context of antimicrobial research various plant extracts have been identified with Quorum Sensing Inhibitory (QSI) activities among bacterial cells. This review focuses on the mechanism of quorum sensing and quorum sensing inhibitors isolated from natural sources.
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Isibor, PO, PA Akinduti, OS Aworunse, JO Oyewale, O. Oshamika, HU Ugboko, OS Taiwo et al. "Significance of African Diets in Biotherapeutic Modulation of the Gut Microbiome". Bioinformatics and Biology Insights 15 (janeiro de 2021): 117793222110126. http://dx.doi.org/10.1177/11779322211012697.
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Diet plays an essential role in human development and growth, contributing to health and well-being. The socio-economic values, cultural perspectives, and dietary formulation in sub-Saharan Africa can influence gut health and disease prevention. The vast microbial ecosystems in the human gut frequently interrelate to maintain a healthy, well-coordinated cellular and humoral immune signalling to prevent metabolic dysfunction, pathogen dominance, and induction of systemic diseases. The diverse indigenous diets could differentially act as biotherapeutics to modulate microbial abundance and population characteristics. Such modulation could prevent stunted growth, malnutrition, induction of bowel diseases, attenuated immune responses, and mortality, particularly among infants. Understanding the associations between specific indigenous African diets and the predictability of the dynamics of gut bacteria genera promises potential biotherapeutics towards improving the prevention, control, and treatment of microbiome-associated diseases such as cancer, inflammatory bowel disease, obesity, type 2 diabetes, and cardiovascular disease. The dietary influence of many African diets (especially grain-base such as millet, maize, brown rice, sorghum, soya, and tapioca) promotes gut lining integrity, immune tolerance towards the microbiota, and its associated immune and inflammatory responses. A fibre-rich diet is a promising biotherapeutic candidate that could effectively modulate inflammatory mediators’ expression associated with immune cell migration, lymphoid tissue maturation, and signalling pathways. It could also modulate the stimulation of cytokines and chemokines involved in ensuring balance for long-term microbiome programming. The interplay between host and gut microbial digestion is complex; microbes using and competing for dietary and endogenous proteins are often attributable to variances in the comparative abundances of Enterobacteriaceae taxa. Many auto-inducers could initiate the process of quorum sensing and mammalian epinephrine host cell signalling system. It could also downregulate inflammatory signals with microbiota tumour taxa that could trigger colorectal cancer initiation, metabolic type 2 diabetes, and inflammatory bowel diseases. The exploitation of essential biotherapeutic molecules derived from fibre-rich indigenous diet promises food substances for the downregulation of inflammatory signalling that could be harmful to gut microbiota ecological balance and improved immune response modulation.
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Zarzyńska, Joanna, Małgorzata Gajewska e Tomasz Motyl. "Effects of hormones and growth factors on TGF-β1 expression in bovine mammary epithelial cells". Journal of Dairy Research 72, n.º 1 (14 de janeiro de 2005): 39–48. http://dx.doi.org/10.1017/s0022029904000639.
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The decline of mammary epithelial cell (MEC) number during mammary gland involution in the cow is due to inhibition of proliferation and induction of apoptosis. Transforming growth factor-beta 1 (TGF-β1) belongs to a group of intramammary auto/paracrine inhibitors of bovine MEC growth and inducers of apoptosis. However, the mechanism responsible for the regulation of TGF-β1 expression in MEC is not known. The present study examined the effect of the hormones, growth hormone (GH), somatostatin (STS), 17-β oestradiol (E2), progesterone (P4), as well as the growth factors, insulin-like growth factor I (IGF-I) and epidermal growth factor (EGF), on TGF-β1 expression in the bovine MEC lines, BME-UV1 and MAC-T. The model of apoptosis in bovine mammary gland in vitro was applied by reduction of fetal bovine serum (FBS) (from 10% to 2% or 0·5% FBS) in the cell environment to show the relationship between TGF-β1 expression and apoptosis in bovine MEC. RT-PCR, Western blot and laser scanning cytometry (LSC) were used for analysis of TGF-β1 transcript and protein level as well as apoptosis and cell cycle in examined MEC. In this model of apoptosis, FBS deficiency (mimicking the naturally occurring decline in the access of bioactive compounds and nutrients at the end of lactation and dry period) was associated with increased TGF-β1 expression at the level of transcript and protein, induction of apoptosis and inhibition of cell cycle. Exogenous TGF-β1, IGF-I, EGF and GH inhibited FBS-deficiency-stimulated TGF-β1 expression. The suppressive effect of GH was reversed when cells were maintained longer in FBS-deficient medium. In general, STS, E2 and P4 increased TGF-β1 expression. However, this effect was dependent on hormone concentration and cell line. BME-UV1 cells were much more responsive to the peptides, GH, STS, IGF-I and EGF, whereas MAC-T cells were more responsive to the steroid sex hormones: E2 and P4.
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Mariño, Guillermo, Federico Pietrocola, Frank Madeo e Guido Kroemer. "Caloric restriction mimetics: natural/physiological pharmacological autophagy inducers". Autophagy 10, n.º 11 (2 de novembro de 2014): 1879–82. http://dx.doi.org/10.4161/auto.36413.
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Man, Na, e Shu-Hong Yu. "Rare earth oxide nanocrystals as a new class of autophagy inducers". Autophagy 6, n.º 2 (16 de fevereiro de 2010): 310–11. http://dx.doi.org/10.4161/auto.6.2.11138.
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Ullah, Aqsa Sana. "Microbial Quorum Sensing and Its Role in Biofilm Formation". Asian Journal of Biology, 15 de julho de 2020, 34–40. http://dx.doi.org/10.9734/ajob/2020/v9i330089.
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Quorum sensing is defined as the effect of fluctuation in cells density on the regulation of gene expression within the cell. Approximately all bacteria produce small molecules (auto-inducers) to control Quorum sensing. S-adenosylmethionine (SAM) is responsible for auto-inducers production in Gram-negative bacteria. Auto-inducers interaction with particular receptors provokes different behaviours that are under the control of Quorum sensing The presence of fungal Quorum sensing systems was bare eleven years before after the sighting that farnesol panels filamentation in the pathogenic polymorphic fungus Candida albicans. In the previous era, farnesol has been shown to play manifold roles in C. albicans physiology as a signalling molecule and encouragement damaging effects on host cells and other microbes. In addition to farnesol, the aromatic alcohol tyrosol was also initiated to be a C. albicans QSM regulatory growth, morphogenesis and bio film formation. In Saccharomyces cerevisiae, two other aromatic alcohols, phenyl ethanol and tryptophol were found to be QSMs regulating morphogenesis during nitrogen starvation conditions. Moreover, population density-dependent performances that look like QS have been labelled in numerous other fungal species. Although fungal QS investigation is still in its beginning, its detection has changed our opinions about the fungal kingdom and might ultimately lead to the growth of new antifungal therapeutics.
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Huang, Jingwen, Jiuzhou Chen, Yu Wang, Tuo Shi, Xiaomeng Ni, Wei Pu, Jiao Liu et al. "Development of a Hyperosmotic Stress Inducible Gene Expression System by Engineering the MtrA/MtrB-Dependent NCgl1418 Promoter in Corynebacterium glutamicum". Frontiers in Microbiology 12 (21 de julho de 2021). http://dx.doi.org/10.3389/fmicb.2021.718511.
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Corynebacterium glutamicum is an important workhorse for industrial production of diversiform bioproducts. Precise regulation of gene expression is crucial for metabolic balance and enhancing production of target molecules. Auto-inducible promoters, which can be activated without expensive inducers, are ideal regulatory tools for industrial-scale application. However, few auto-inducible promoters have been identified and applied in C. glutamicum. Here, a hyperosmotic stress inducible gene expression system was developed and used for metabolic engineering of C. glutamicum. The promoter of NCgl1418 (PNCgl1418) that was activated by the two-component signal transduction system MtrA/MtrB was found to exhibit a high inducibility under hyperosmotic stress conditions. A synthetic promoter library was then constructed by randomizing the flanking and space regions of PNCgl1418, and mutant promoters exhibiting high strength were isolated via fluorescence activated cell sorting (FACS)-based high-throughput screening. The hyperosmotic stress inducible gene expression system was applied to regulate the expression of lysE encoding a lysine exporter and repress four genes involved in lysine biosynthesis (gltA, pck, pgi, and hom) by CRISPR interference, which increased the lysine titer by 64.7% (from 17.0 to 28.0 g/L) in bioreactors. The hyperosmotic stress inducible gene expression system developed here is a simple and effective tool for gene auto-regulation in C. glutamicum and holds promise for metabolic engineering of C. glutamicum to produce valuable chemicals and fuels.
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Tumminia, Matteo, Dario Valentini, Giovanni Pace, Ruzbeh Hadavandi, Lucio Torre, Angelo Pasini e Luca d'Agostino. "Maximum Likelihood Identification of Cavitation Instabilities in Axial Inducers". Journal of Fluids Engineering, 3 de setembro de 2022. http://dx.doi.org/10.1115/1.4055473.
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Abstract The article illustrates the results of an exploratory study on the effectiveness of maximum likelihood Bayesian estimation in the identification of cavitation instabilities in axial inducers using the blade-to-blade pressure measured by a single transducer flush-mounted on the impeller casing. The typical azimuthal distribution of the pressure in the blade channels is parameterized and modulated in space and time for theoretically reproducing the expected pressure generated by known forms of cavitation instabilities (cavitation surge auto-oscillations, n-lobed synchronous/asynchronous rotating cavitation, higher-order surge/rotating cavitation modes). The power spectra of the theoretical pressure so obtained in the rotating frame are transformed in the stationary frame, corrected for frequency broadening effects, and parametrically fitted by maximum likelihood estimation to the measurements of the pressure on the inducer casing just downstream of the blade leading edges. In addition to its fundamental frequency, each form of instability generates a characteristic spectral distribution of sidebands. The identification uses this information for successfully discriminating flow oscillation modes occurring simultaneously with intensities differing by up to one order of magnitude. The method returns the estimates of the model parameters and their standard errors, allowing one to assess the accuracy and statistical significance of the identification. The results first demonstrate that elementary maximum likelihood Bayesian identification is indeed capable to effectively detect and characterize the occurrence of flow instabilities in cavitating inducers at a fraction of the experimental and post-processing costs and complexities of traditional cross-correlation methods.
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Naga, Nourhan G., Dalia E. El-Badan, Khaled M. Ghanem e Mona I. Shaaban. "It is the time for quorum sensing inhibition as alternative strategy of antimicrobial therapy". Cell Communication and Signaling 21, n.º 1 (14 de junho de 2023). http://dx.doi.org/10.1186/s12964-023-01154-9.
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AbstractMultiple drug resistance poses a significant threat to public health worldwide, with a substantial increase in morbidity and mortality rates. Consequently, searching for novel strategies to control microbial pathogenicity is necessary. With the aid of auto-inducers (AIs), quorum sensing (QS) regulates bacterial virulence factors through cell-to-cell signaling networks. AIs are small signaling molecules produced during the stationary phase. When bacterial cultures reach a certain level of growth, these molecules regulate the expression of the bound genes by acting as mirrors that reflect the inoculum density.Gram-positive bacteria use the peptide derivatives of these signaling molecules, whereas Gram-negative bacteria use the fatty acid derivatives, and the majority of bacteria can use both types to modulate the expression of the target gene. Numerous natural and synthetic QS inhibitors (QSIs) have been developed to reduce microbial pathogenesis. Applications of QSI are vital to human health, as well as fisheries and aquaculture, agriculture, and water treatment.
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Vani, S., Kayeen Vadakkan e Bince Mani. "A narrative review on bacterial biofilm: its formation, clinical aspects and inhibition strategies". Future Journal of Pharmaceutical Sciences 9, n.º 1 (5 de junho de 2023). http://dx.doi.org/10.1186/s43094-023-00499-9.
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Abstract Background The predominant mode of life of most of the bacteria is their biofilm state. Based on the type of bacteria existing within the biofilm, it might be beneficial or harmful. Its beneficial aspects have been exploited mostly in waste management strategies. These biofilms affected the food industry, dairy industry and oil industry, causing huge losses by food spoilage, reduced heat transfer efficiencies and corrosion caused by biofilms in pipelines. They were considered a crucial risk to human well-being. Biofilms were responsible for more than 75% of the clinical infections caused in humans. The main body of the abstract Biofilms are multimicrobial complex structures that are resistant to antibiotics and stressful environments. The biofilm stage may provide various advantages to the bacteria during bacterial infections in human beings. The extracellular polymeric substances hold the bacterial community colonized in the biofilm. The bacteria within the biofilm are more resistant to antibiotics, whereas the planktonic bacteria are susceptible to them. Quorum sensing regulated biofilm formation, which can be manipulated to eradicate devastating effects caused by biofilms. The occurrence of biofilm on the clinical devices leads to the malfunction of the implants and complicates the patients’ health conditions. Biofilms also cause non-device-associated health problems. The major anti-biofilm strategies are the utilization of enzymatic activity and hindrance of quorum sensing. The auto-inducers, which play a major role in quorum sensing, are mimicked by inhibitors. This prevents the binding of auto-inducers to the receptors, eventually leading to blockage of biofilm formation. Short conclusion The significant background knowledge regarding the biofilm, its formation, clinical aspects and inhibition strategies has been highlighted in this review. This information dissipated anticipates new applications of plant compounds as an alternative to antibiotics, since they may act as anti-quorum sensing molecules. For instance, inhibitory compounds like Linalool and eugenol from the essential oil of different plants displayed antibiofilm activity against biofilms formed by Streptococcus pyogenes and Porphyromonas gingivalis, respectively. Further research is required to exploit the inhibitory properties of the various other bioactive compounds present in plant extract, and thereby, we can protect human beings from several device and non-device-related infections caused by biofilms such as catheter-related bloodstream infections, tuberculosis, cystic fibrosis, chronic obstructive pulmonary diseases, dental caries and periodontitis.
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Gimpel, Anna-Katharina, Antonio Maccataio, Harald Unterweger, Maria V. Sokolova, Georg Schett e Ulrike Steffen. "IgA Complexes Induce Neutrophil Extracellular Trap Formation More Potently Than IgG Complexes". Frontiers in Immunology 12 (13 de janeiro de 2022). http://dx.doi.org/10.3389/fimmu.2021.761816.
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Neutrophil extracellular trap (NET) formation is a powerful instrument to fight pathogens, but may induce collateral damage in the affected tissues. Besides pathogen-derived factors, immune complexes are potent inducers of NET formation. Neutrophils express IgA and IgG specific Fc receptors (FcRs) and therefore respond to complexed IgA and IgG. Especially in the context of autoimmune diseases, IgA and IgG immune complexes have been shown to trigger NET formation, a process that putatively contributes to disease severity. However, it is of question if both antibody classes stimulate neutrophils to the same extent. In this study, we compared the capability of IgA and IgG complexes formed by heat aggregation to induce NET formation. While stimulation of neutrophils with IgA complexes robustly induced NET formation, complexed IgG only marginally increased the amount of NETs compared to the unstimulated control. Mixing IgA with IgG before heat aggregation did not increase the effect of complexed IgA on neutrophils. By contrast, the presence of IgG complexes seemed to disturb neutrophil stimulation by IgA complexes. The capacity of complexed IgG to induce NET formation could not be increased by the addition of autologous serum or the removal of terminal sialic acid in the Fc glycan. Together, our data show that IgA is a much more potent inducer of NET formation than IgG. IgA may thus be the main driving force in (auto)immune complex-mediated NET formation.
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Hartmann, Anton, Sophia Klink e Michael Rothballer. "Plant Growth Promotion and Induction of Systemic Tolerance to Drought and Salt Stress of Plants by Quorum Sensing Auto-Inducers of the N-acyl-homoserine Lactone Type: Recent Developments". Frontiers in Plant Science 12 (31 de maio de 2021). http://dx.doi.org/10.3389/fpls.2021.683546.
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de Carvalho Oliveira, Vanessa, Olga Tatsiy e Patrick P. McDonald. "Phosphoinositol 3-kinase-driven NET formation involves different isoforms and signaling partners depending on the stimulus". Frontiers in Immunology 14 (24 de janeiro de 2023). http://dx.doi.org/10.3389/fimmu.2023.1042686.
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Neutrophil extracellular traps (NETs) serve to immobilize and kill pathogens, but also can contribute to the progression of several inflammatory and auto-immune diseases, as well as cancer. Whence the importance of elucidating the mechanisms underlying NET formation. In this regard, the PI3K signaling pathway has been shown to be crucial; yet little is known about which of its components are involved. Here, we identified the PI3K isoforms and associated signaling partners that are mobilized in response to different classes of physiological NET inducers (inflammatory cytokines, growth factors, chemoattractants). NET generation was assessed by microscopy and signalling molecule activation by immunoblot using phospho-antibodies. Across the various stimuli, PI3Kα and PI3Kγ isoforms clearly contributed to NET induction, while the participation of other isoforms was stimulus-dependent. Some PI3K isoforms were also found to signal through Akt, the canonical downstream effector of PI3K, while others did not. Downstream of PI3K, mTOR and PLCγ2 were used by all stimuli to control NET generation. Conversely, the involvement of other kinases depended on the stimulus – both TNFα and GM-CSF relied on PDK1 and Akt; and both TNFα and fMLP additionally used S6K. We further established that all PI3K isoforms and downstream effectors act belatedly in NET generation, as reported previously for PI3K. Finally, we revisited the PI3K-PDK1-Akt signaling hierarchy in human neutrophils and again found stimulus-dependent differences. Our data uncover unsuspected complexity and redundancy in the signaling machinery controlling NET formation through the all-important PI3K pathway. Conserved signaling molecules represent therapeutic targets for pathologies involving NETs and in this regard, the existence of drugs currently used in the clinic or undergoing clinical trials (which target PI3K isoforms, mTOR or Akt), underscores the translational potential of our findings.
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Chao, Shuangying, Yuhang Liu, Ning Ding, Yue Lin, Qian Wang, Junwen Tan, Wei Li, Yang Zheng, Xuejun Hu e Junming Li. "Highly Expressed Soluble Recombinant Anti-GFP VHHs in Escherichia coli via Optimized Signal Peptides, Strains, and Inducers". Frontiers in Molecular Biosciences 9 (10 de março de 2022). http://dx.doi.org/10.3389/fmolb.2022.848829.
Texto completo da fonteResumo:
Antigen-binding variable domains of the H chain of heavy-chain antibodies (VHHs), also known as nanobodies (Nbs), are of great interest in imaging technique, disease prevention, diagnosis, and therapy. High-level expression of soluble Nbs is very important for its industrial production. In this study, we optimized the expression system of anti-green fluorescent protein (GFP) VHHs with three different signal peptides (SPs), outer-membrane protein A (OmpA), pectate lyase B (PelB), and L-asparaginase II SP (L-AsPsII), in different Escherichia coli strains via isopropyl β-D-thiogalactoside (IPTG) induction and auto-induction, respectively. The solubility of recombinant anti-GFP VHHs with PelB or OmpA was significantly enhanced to the same extent by IPTG induction and auto-induction in BL21 (DE3) E. coli strain and the maximum yield of target protein reached approximately 0.4 mg/l in a shake flask. The binding activity of recombinant anti-GFP VHHs was also confirmed to be retained by native-polyacrylamide gel electrophoresis (PAGE). These results suggest that SPs like OmpA and PelB could efficiently improve the recombinant anti-GFP VHH solubility without changing its bioactivity, providing a novel strategy to optimize the E. coli expression system of soluble VHHs, and lay the foundation for the industrial production of soluble recombinant anti-GFP VHHs and the research of other VHHs in the future.