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Nitrite and nitric oxide (NO) are well-known bacteriostatic agents with similar biochemical properties. However, many studies have demonstrated that inhibition of bacterial growth by nitrite is independent of NO. Here, with Shewanella oneidensis as the research model because of its unusually high cytochrome (cyt) c content, we identify a common mechanism by which nitrite and NO compromise cyt c biosynthesis in bacteria, and thereby inhibit respiration. This is achieved by eliminating the inference of the cyclic adenosine monophosphate-catabolite repression protein (cAMP-Crp), a primary regulatory system that controls the cyt c content and whose activity is subjected to the repression of nitrite. Both nitrite and NO impair the CcmE of multiple bacteria, an essential heme chaperone of the System I cyt c biosynthesis apparatus. Given that bacterial targets of nitrite and NO differ enormously and vary even in the same genus, these observations underscore the importance of cyt c biosynthesis for the antimicrobial actions of nitrite and NO. [ABSTRACT FROM AUTHOR]

Summary: Thiosulfate, an important form of sulfur compounds, can serve as both electron donor and acceptor in various microorganisms. In Shewanella oneidensis, a bacterium renowned for respiratory versatility, thiosulfate reduction has long been recognized but whether it can catalyse thiosulfate oxidation remains elusive. In this study, we discovered that S. oneidensis is capable of thiosulfate oxidation, a process specifically catalysed by two periplasmic cytochrome c (cyt c) proteins, TsdA and TsdB, which act as the catalytic subunit and the electron transfer subunit respectively. In the presence of oxygen, oxidation of thiosulfate has priority over reduction. Intriguingly, thiosulfate oxidation negatively regulates the cyt c content in S. oneidensis cells, largely by reducing intracellular levels of cAMP, which as the cofactor modulates activity of global regulator Crp required for transcription of many cyt c genes. This unexpected finding provides an additional dimension to interplays between the respiration regulator and the respiratory pathways in S. oneidensis. Moreover, the data presented here identified S. oneidensis as the first bacterium known to date owning both functional thiosulfate reductase and dehydrogenase, and importantly, genomics analyses suggested that the number of bacterial species possessing this feature is rather limited. [ABSTRACT FROM AUTHOR]

Summary: Shewanella oneidensis is the best understood model organism for the study of dissimilatory iron reduction. This review focuses on the current state of our knowledge regarding this extracellular respiratory process and highlights its physiologic, regulatory and biochemical requirements. It seems that we have widely understood how respiratory electrons can reach the cell surface and what the minimal set of electron transport proteins to the cell surface is. Nevertheless, even after decades of work in different research groups around the globe there are still several important questions that were not answered yet. In particular, the physiology of this organism, the possible evolutionary benefit of some responses to anoxic conditions, as well as the exact mechanism of electron transfer onto solid electron acceptors are yet to be addressed. The elucidation of these questions will be a great challenge for future work and important for the application of extracellular respiration in biotechnological processes. Extracellular respiration is a key factor for the geobiochemical cycling of elements in soil and sediments and enables a variety of microbe–electrode interaction based applications. Shewanella oneidensis is the best understood model organism for extracellular respiration. This review provides an overview of the molecular details of this process and gives insight into the physiological framework of the organism. [ABSTRACT FROM AUTHOR]

The availability of increasingly inexpensive sequencing combined with an ever-expanding molecular biology toolbox has transported classical bacterial genetics into the 21st century. Whole genome genetic fitness analysis using transposon mutagenesis combined with next-generation high-throughput sequencing ( Tn-seq) promises to revolutionize systems level analysis of microbial metabolism. Tn-seq measures the frequency of actual members of a heterogeneous mutant pool undergoing purifying selection to determine the contribution of every non-essential gene in the genome to the fitness of an organism under a given condition. Here we use Tn-seq to assess gene function in the Gram negative γ-proteobacterium Shewanella oneidensis strain MR-1. In addition to being a model environmental organism, there is considerable interest in using S. oneidensis as a platform organism for bioremediation and biotechnology, necessitating a complete understanding of the metabolic pathways that may be utilized. Our analysis reveals unique aspects of S. oneidensis metabolism overlooked by over 30 years of classical genetic and systems level analysis. We report the utilization of an alternative citrate synthase and describe a dynamic branching of the S. oneidensis anaerobic tricarboxylic acid cycle, unreported in any other organism, which may be a widespread strategy for microbes adept at dissipating reducing equivalents via anaerobic respiration. [ABSTRACT FROM AUTHOR]

Classical swine fever virus (CSFV) causes a severe disease of pigs that is characterized by hemorrhage, disseminated intravascular coagulation, and leucopenia. Until now, the role of the nonstructural protein 5A (NS5A) produced by CSFV in the pathogenesis of CSF is not well known. In this study, we investigated the function of CSFV NS5A by examining its role in the induction of oxidative stress and related intracellular events. Stable swine umbilical vein endothelial cell lines expressing CSFV NS5A were established and showed that CSFV NS5A is localized to endoplasmic reticulum and induces oxidative stress associated with enhanced reactive oxygen species production. The expression of NS5A protein exerts different effects on the three major antioxidants. Particularly, it exhibits a significant increase in transcriptional activities of antioxidant proteins thioredoxin and peroxiredoxin-6, but accompanied by a concomitant decrease of antioxidant protein heme oxygenase-1. Further studies showed that cyclooxygenase-2, a pro-inflammatory protein related to oxidative stress, is up-regulated while anti-inflammatory protein peroxisome proliferator-activated receptor-γ, an important mediator in vascular functional regulation, is down-regulated in CSFV NS5A expressing cells. This study suggested that CSFV NS5A plays important roles in the induction of oxidative stress and inflammatory response in vascular endothelial cells. These findings provide novel information on the function of the poorly characterized CSFV NS5A and provide an insight into the mechanism by which CSFV NS5A can alter intracellular events associated with the viral infection. [ABSTRACT FROM AUTHOR]

Under inflammatory conditions, macrophages can differentiate into different functional subtypes. We show that bone marrow-derived macrophages constitutively express different levels of various complement-related genes. The relative expression levels are C1qb > Crry > CFH > C3 > C1r > CFB > DAF1 > CD59a > C2 > C1INH > C1s > C4. Upon activation, the expression of C1r, C1s, C3, C2, CFB, and C1INH was up-regulated, and CFH, CD59a, and DAF1, down-regulated in M1 (induced by interferon-γ + lipopolysaccharides (LPS)) and M2b (induced by immune complex + LPS) macrophages. The expression of C4 and CFH was slightly up-regulated in interleukin (IL)-10-induced M2c macrophages. Complement gene expression in IL-4-induced M2a macrophages was weakly down-regulated as compared to resting M0 macrophages. Higher levels of C3, C1INH, and CFB but lower levels of CFH expression in M1 and M2b macrophage suggests that they may be involved in the alternative pathway of complement activation during inflammation. [ABSTRACT FROM AUTHOR]

Hepatic stellate cells (HSCs) undergo activation during the development of liver fibrosis. Transcription factor myocyte enhancer factor (MEF2) 2C plays a key role in this process. In the present study, we investigated the effect of hydroxysafflor yellow A (HSYA) on hepatic fibrosis and further investigated potential mechanisms in vivo. Sprague-Dawley rats were administered with CCl4 together with or without HYSA for 12 weeks. The effect of HYSA on hepatic fibrosis was evaluated using hematoxylin-eosin and Van Gieson staining. Messenger RNA expression was quantified by real-time polymerase chain reaction, and protein was quantified by Western blot or immunohistochemistry. Our results revealed that CCl4 treatment induced micronodular hepatic fibrosis with a pronounced deposition of collagen fibers. Treatment with HYSA resulted in a significant decrease in fibrosis, protein expression of α-SMA, and MEF-2C gene expression. This was accompanied by a decreased expression of Tβ-RI, Tβ-RII, MEKK3, MEK5, and phosphorylation of ERk5. HYSA alone had no effect on the measured parameters. Our findings demonstrate that HSYA protected, at least in part, the rat liver from CCl4-caused fibrogenesis through inhibition of hepatic stellate cell (HSC) activation, attenuation of transforming growth factor beta (TGF-β) signaling. HSYA may become a novel and promising agent for the inhibition of hepatic fibrosis. [ABSTRACT FROM AUTHOR]

Aims: Chlorophyllin (CHLN), a synthetic derivative of chlorophyll, was assayed in the replication of poliovirus (PV-1) and bovine herpesvirus (BoHV-1) in HEp-2 cell cultures. Methods and Results: Virucidal activity of CHLN was evaluated and the time-of-addition assay was performed as follows: before the infection (−1 and −2 h), at the time of the infection (0 h) and after the infection (1 and 2 h). Plaque reduction assay (PRA) showed that CHLN inhibited BoHV-1 and PV-1 infection and the 50% inhibitory concentrations (IC50) against BoHV-1 and PV-1 infection were 8·6 and 19·8 μg ml−1, respectively. The time-of-addition study demonstrated that the CHLN was effective inhibiting viral replication in 51% and 66·5% for PV-1 and BoHV-1, respectively, at the highest concentration of 20·0 μg ml−1, when added during the infection. The directed effect of CHLN on viral strains demonstrated an inhibition of 62% and 66·4% for PV-1 and BoHV-1, respectively, by PRA. Conclusions: These results demonstrated that CHLN could be used as an antiviral suggesting directed activity on virus particles and on virus-receptor sites to BoHV. For poliovirus, CHLN also demonstrated virucide activity, moreover, showed to inhibit early steps of the replication cycle. Significance and Impact of the Study: CHLN demonstrated promising selectivity index for both virus strains; therefore, it can be used for the development of an antiviral agent. [ABSTRACT FROM AUTHOR]

Arc (anoxic redox control), one of the most intensely investigated two-component regulatory systems in γ-proteobacteria, plays a major role in mediating the metabolic transition from aerobiosis to anaerobiosis. In Shewanella oneidensis, a research model for respiratory versatility, Arc is crucial for aerobic growth. However, how this occurs remains largely unknown. In this study, we demonstrated that the loss of the response regulator ArcA distorts the correlation between transcription and translation by inhibiting the ribosome biosynthesis. This effect largely underlies the growth defect because it concurs with the effect of chloramphenicol, which impairs translation. Reduced transcription of ArcA-dependent ribosomal protein S1 appears to have a significant impact on ribosome assembly. We further show that the lowered translation efficiency is not accountable for the envelope defect, another major defect resulting from the ArcA loss. Overall, our results suggest that although the arcA mutation impairs growth through multi-fold complex impacts in physiology, the reduced translation efficacy appears to be a major cause for the phenotype, demonstrating that Arc is a primary system that coordinates proteomic resources with metabolism in S. oneidensis. [ABSTRACT FROM AUTHOR]

Rhamnus alaternus, is a wild-growing shrub, belonging to the Rhamnaceae family. Widely distributed in the Mediterranean basin, R. alaternus is used in the usual medicine in numerous countries, mostly Tunisia, Algeria, Morocco, Spain, France, Italy, and Croatia. A large number of disorders—including dermatological complications, diabetes, hepatitis, and goiter problems—can be treated by the various parts of R. alaternus (i.e., roots, bark, berries, and leaves). Several bioactive compounds were isolated from R. alaternus, including flavonoids, anthocyanins, and anthraquinones, and showed several effects such as antioxidant, antihyperlipidemic, antigenotoxic, antimutagenic, antimicrobial, and antiproliferative. This review summarizes the updated information concerning the botanical description, distribution, extraction processes applied on R. alaternus, and its ethnopharmacology, toxicity, phytochemistry, and pharmacological effects. [ABSTRACT FROM AUTHOR]

ORAL ABSTRACT Pharmacological enhancement of IL?15 signaling to improve ?shock?and?kill? strategies against latent HIV J.N. Howard[sup.1] , A. Bosque[sup.1] [sup.1] George Washington University, Microbiology, Immunology, and Tropical Medicine, Washington DC, [...]

Today's generation of adolescents and young adults are growing up immersed in social media, such as Facebook and Twitter, that promote user-generated content and interactions between users (Lenhart et al. [...]