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Modular biosynthetic machineries such as polyketide synthases (PKSs) or nonribosomal peptide synthetases (NRPSs) give rise to a vast structural diversity of bioactive metabolites indispensable in the treatment of cancer or infectious diseases. Here, we provide evidence for different evolutionary processes leading to the diversification of modular NRPSs and thus, their respective products. Discovery of a novel lipo-octapeptide family from Pseudomonas , the virginiafactins, and detailed structure elucidation of closely related peptides, the cichofactins and syringafactins, allowed retracing recombinational diversification of the respective NRPS genes. Bioinformatics analyses allowed us to spot an evolutionary snapshot of these processes, where recombination occurred both within the same and between different biosynthetic gene clusters. Our systems feature a recent diversification process, which may represent a typical paradigm to variations in modular biosynthetic machineries., (This journal is © The Royal Society of Chemistry 2019.)

Microbially produced 3-acyltetramic acids display a diverse range of biological activities. The pyreudiones are new members of this class that were isolated from bacteria of the genus Pseudomonas . Here, we performed a structure-activity relationship study and determined their mode of action. An efficient biomimetic synthesis was developed to synthesize pyreudione A. Pyreudiones and synthetic analogs thereof were tested for their amoebicidal, antibacterial, antiproliferative, and cytotoxic activities. The length of the alkyl side chain and the nature of the amino acid residues within the tetramic acid moiety strongly affected activity, in particular against mycobacteria. The mode of action was shown to correlate with the ability of pyreudiones to act as protonophores. Removal of the acidic proton by methylation of pyreudione A resulted in a loss of bioactivity.

Interactions between glycans and glycan binding proteins are essential for numerous processes in all kingdoms of life. Glycan microarrays are an excellent tool to examine protein-glycan interactions. Here, we present a microbe-focused glycan microarray platform based on oligosaccharides obtained by chemical synthesis. Glycans were generated by combining different carbohydrate synthesis approaches including automated glycan assembly, solution-phase synthesis, and chemoenzymatic methods. The current library of more than 300 glycans is as diverse as the mammalian glycan array from the Consortium for Functional Glycomics and, due to its microbial focus, highly complementary. This glycan platform is essential for the characterization of various classes of glycan binding proteins. Applications of this glycan array platform are highlighted by the characterization of innate immune receptors and bacterial virulence factors as well as the analysis of human humoral immunity to pathogenic glycans.

Gunn rats bear a mutation within the uridine diphosphate glucuronosyltransferase-1a1 ( Ugt1a1 ) gene resulting in high serum bilirubin levels as seen in Crigler-Najjar syndrome. In this study, the Gunn rat was used as an animal model for heritable liver dysfunction. Induced mesenchymal stem cells (iMSCs) derived from embryonic stem cells (H1) and induced pluripotent stem cells were transplanted into Gunn rats after partial hepatectomy. The iMSCs engrafted and survived in the liver for up to 2 months. The transplanted iMSCs differentiated into functional hepatocytes as evidenced by partially suppressed hyperbilirubinemia and expression of multiple human-specific hepatocyte markers such as albumin, hepatocyte nuclear factor 4α, UGT1A1 , cytokeratin 18, bile salt export pump, multidrug resistance protein 2, Na/taurocholate-cotransporting polypeptide, and α-fetoprotein. These findings imply that transplanted human iMSCs can contribute to liver regeneration in vivo and thus represent a promising tool for the treatment of inherited liver diseases.

The laminin α5 protein chain is an element of basement membranes and important to maintain stem cells. Hepatic stellate cells (HSC) are liver-resident mesenchymal stem cells, which reside in a quiescent state on a basement membrane-like structure in the space of Dissé. In the present study, laminin α5 chain was detected in the space of Dissé of normal rat liver. Since HSC are critical for liver regeneration and can contribute to fibrosis in chronic liver diseases, the effect of laminins on HSC maintenance was investigated. Therefore, isolated rat HSC were seeded on uncoated polystyrene (PS) or PS coated with either laminin-521 (PS/LN-521) or laminin-211 (PS/LN-211). PS/LN-521 improved HSC adhesion and better preserved their retinoid stores as well as quiescence- and stem cell-associated phenotype, whereas HSC on PS/LN-211 or PS developed into myofibroblasts-like cells. To improve the homogeneity as well as the presentation of laminin molecules on the culture surface to HSC, laminin-functionalized, gold-nanostructured glass surfaces were generated. This approach further enhanced the expression of quiescence-associated genes in HSC. In conclusion, the results indicate that LN-521 supports the quiescent state of HSC and laminin α5 can be regarded as an important element of their niche in the space of Dissé., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Fully synthetic glycan-based vaccines hold great potential as preventive and therapeutic vaccines against infectious diseases as well as cancer. Here, we present a two-component platform based on the facile conjugation of carbohydrate antigens to α-galactosylceramide (α-GalCer) to yield fully synthetic vaccine candidates. Formulation of the cancer-associated Tn antigen glycolipid model vaccine candidate into liposomes of different sizes and subsequent immunization of mice generated specific, high-affinity antibodies against the carbohydrate antigen with characteristics of T cell-dependent immunity. Liposome formulation elicited more reproducible glycan immunity than a conventional glycoconjugate vaccine bearing the same glycan antigen did. Further evaluation of the immune response revealed that the size of the liposomes influenced the glycan antibody responses toward either a cellular (Th1) or a humoral (Th2) immune phenotype. The glycolipid vaccine platform affords strong and robust antiglycan antibody responses in vivo without the need for an external adjuvant.

Investigating microbial interactions from an ecological perspective is a particularly fruitful approach to unveil both new chemistry and bioactivity. Microbial predator-prey interactions in particular rely on natural products as signal or defense molecules. In this context, we identified a grazing-resistant Pseudomonas strain, isolated from the bacterivorous amoeba Dictyostelium discoideum. Genome analysis of this bacterium revealed the presence of two biosynthetic gene clusters that were found adjacent to each other on a contiguous stretch of the bacterial genome. Although one cluster codes for the polyketide synthase producing the known antibiotic mupirocin, the other cluster encodes a nonribosomal peptide synthetase leading to the unreported cyclic lipopeptide jessenipeptin. We describe its complete structure elucidation, as well as its synergistic activity against methicillin-resistant Staphylococcus aureus , when in combination with mupirocin. Both biosynthetic gene clusters are regulated by quorum-sensing systems, with 3-oxo-decanoyl homoserine lactone (3-oxo-C10-AHL) and hexanoyl homoserine lactone (C6-AHL) being the respective signal molecules. This study highlights the regulation, richness, and complex interplay of bacterial natural products that emerge in the context of microbial competition., Competing Interests: The authors declare no conflict of interest.

Hepatic stellate cells (HSCs) are mesenchymal stem cells (MSCs) of the liver. They are unique among MSCs, since HSCs remain in a quiescent, retinoid-storing state in the normal liver but become activated after liver injury and contribute to tissue repair. The epigenetic mechanisms accompanying the transition of HSCs from a quiescent to an activated state are in the focus of the present study. We investigated the methylome and transcriptome during this process and observed profound changes. While the promoter methylation correlated negatively with gene expression, the gene-body methylation revealed no clear correlation. Most genes with altered expression were associated with cell differentiation. Among them, Wilms tumor 1 (Wt1) and Deltex4 (Dtx4) genes were identified as epigenetically regulated. Since HSCs were reported to derive from multipotent Wt1-positive cells and many differentially expressed genes were associated with cell differentiation during their activation, epigenetic alterations are presumably required to enable HSC development.

Crustaceans are intensively farmed in aquaculture facilities where they are vulnerable to parasites, bacteria, or viruses, often severely compromising the rearing success. The ubiquitin-proteasome system (UPS) is crucial for the maintenance of cellular integrity. Analogous to higher vertebrates, the UPS of crustaceans may also play an important role in stress resistance and pathogen defense. We studied the general properties of the proteasome system in the hemocytes of the whiteleg shrimp, Penaeus vannamei, and the European brown shrimp Crangon crangon. The 20S proteasome was the predominant proteasome population in the hemocytes of both species. The specific activities of the trypsin-like (Try-like), chymotrypsin-like (Chy-like), and caspase-like (Cas-like) enzymes of the shrimp proteasome differed between species. P. vannamei exhibited a higher ratio of Try-like to Chy-like activities and Cas-like to Chy-like activities than C. crangon. Notably, the Chy-like activity of P. vannamei showed substrate or product inhibition at concentrations of more than 25 mmol L -1 . The K M values ranged from 0.072 mmol L -1 for the Try-like activity of P. vannamei to 0.309 mmol L -1 for the Cas-like activity of C. crangon. Inhibition of the proteasome of P. vannamei by proteasome inhibitors was stronger than in C. crangon. The pH profiles were similar in both species. The Try-like, Chy-like, and Cas-like sites showed the highest activities between pH 7.5 and 8.5. The proteasomes of both species were sensitive against repeated freezing and thawing losing ~80-90% of activity. This study forms the basis for future investigations on the shrimp response against infectious diseases, and the role of the UPS therein.

The class of cyclic lipopeptide natural products consists of compounds with a diverse range of bioactivities. In this study, we elucidated the structure of the cyclic lipopeptide anikasin using X-ray crystallography, analyzed its biosynthetic gene cluster, and investigated its natural role in the interaction between the producer strain Pseudomonas fluorescens HKI0770 and protozoal predators. These results led to the conclusion that anikasin has dual functionality enabling swarming motility and acting as a niche amoebicide, which effectively inhibits the social amoeba Polysphondylium violaceum and protects the producer strain from protozoal grazing.

In recent years, biofilms have become a central subject of research in the fields of microbiology, medicine, agriculture, and systems biology, among others. The sociomicrobiology of multispecies biofilms, however, is still poorly understood. Here, we report a screening system that allowed us to identify soil bacteria which induce architectural changes in biofilm colonies when cocultured with Bacillus subtilis We identified the soil bacterium Lysinibacillus fusiformis M5 as an inducer of wrinkle formation in B. subtilis colonies mediated by a diffusible signaling molecule. This compound was isolated by bioassay-guided chromatographic fractionation. The elicitor was identified to be the purine hypoxanthine using mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy. We show that the induction of wrinkle formation by hypoxanthine is not dependent on signal recognition by the histidine kinases KinA, KinB, KinC, and KinD, which are generally involved in phosphorylation of the master regulator Spo0A. Likewise, we show that hypoxanthine signaling does not induce the expression of biofilm matrix-related operons epsABCDEFGHIJKLMNO and tasA-sipW-tapA Finally, we demonstrate that the purine permease PbuO, but not PbuG, is necessary for hypoxanthine to induce an increase in wrinkle formation of B. subtilis biofilm colonies. Our results suggest that hypoxanthine-stimulated wrinkle development is not due to a direct induction of biofilm-related gene expression but rather is caused by the excess of hypoxanthine within B. subtilis cells, which may lead to cell stress and death. IMPORTANCE Biofilms are a bacterial lifestyle with high relevance regarding diverse human activities. Biofilms can be beneficial, for instance, in crop protection. In nature, biofilms are commonly found as multispecies communities displaying complex social behaviors and characteristics. The study of interspecies interactions will thus lead to a better understanding and use of biofilms as they occur outside laboratory conditions. Here, we present a screening method suitable for the identification of multispecies interactions and showcase L. fusiformis as a soil bacterium that is able to live alongside B. subtilis and modify the architecture of its biofilms., (Copyright © 2017 American Society for Microbiology.)

Frequency shifts in signals of bats flying near conspecifics have been interpreted as a spectral jamming avoidance response (JAR). However, several prerequisites supporting a JAR hypothesis have not been controlled for in previous studies. We recorded flight and echolocation behavior of foraging Pipistrellus pipistrellus while flying alone and with a conspecific and tested whether frequency changes were due to a spectral JAR with an increased frequency difference, or whether changes could be explained by other reactions. P. pipistrellus reacted to conspecifics with a reduction of sound duration and often also pulse interval, accompanied by an increase in terminal frequency. This reaction is typical of behavioral situations where targets of interest have captured the bat's attention and initiated a more detailed exploration. All observed frequency changes were predicted by the attention reaction alone, and do not support the JAR hypothesis of increased frequency separation. Reaction distances of 1-11 m suggest that the attention response may be elicited either by detection of the conspecific by short range active echolocation or by long range passive acoustic detection of echolocation calls.

Bacterial defense mechanisms have evolved to protect bacteria against predation by nematodes, predatory bacteria, or amoebae. We identified novel bacterial alkaloids (pyreudiones A-D) that protect the producer, Pseudomonas fluorescens HKI0770, against amoebal predation. Isolation, structure elucidation, total synthesis, and a proposed biosynthetic pathway for these structures are presented. The generation of P. fluorescens gene-deletion mutants unable to produce pyreudiones rendered the bacterium edible to a variety of soil-dwelling amoebae., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Hepatic stellate cells (HSCs) were recently identified as liver-resident mesenchymal stem cells. HSCs are activated after liver injury and involved in pivotal processes, such as liver development, immunoregulation, regeneration, and also fibrogenesis. To date, several studies have reported candidate pathways that regulate the plasticity of HSCs during physiological and pathophysiological processes. Here we analyzed the expression changes and activity of the RAS family GTPases and thereby investigated the signaling networks of quiescent HSCs versus activated HSCs. For the first time, we report that embryonic stem cell-expressed RAS (ERAS) is specifically expressed in quiescent HSCs and down-regulated during HSC activation via promoter DNA methylation. Notably, in quiescent HSCs, the high level of ERAS protein correlates with the activation of AKT, STAT3, mTORC2, and HIPPO signaling pathways and inactivation of FOXO1 and YAP. Our data strongly indicate that in quiescent HSCs, ERAS targets AKT via two distinct pathways driven by PI3Kα/δ and mTORC2, whereas in activated HSCs, RAS signaling shifts to RAF-MEK-ERK. Thus, in contrast to the reported role of ERAS in tumor cells associated with cell proliferation, our findings indicate that ERAS is important to maintain quiescence in HSCs., (© 2016 by The American Society for Biochemistry and Molecular Biology, Inc.)

BACKGROUND: Septic arthritis is a rare complication after anterior cruciate ligament surgery. All case series reported so far have been retrospective, and case numbers of septic arthritis have ranged from 4 to 11. HYPOTHESIS: A stage-adapted treatment regimen for septic arthritis after anterior cruciate ligament surgery can provide reliable results. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: From June 1993 to May 2003, 24 patients met the inclusion criteria for this study. The average age at trauma was 32.5 years. Treatment protocol was based on the grade of infection. Options included transarthroscopic treatment for Gaechter grades 1 and 2 infections or medial and lateral arthrotomy for grades 3 and 4 infections. Graft retention was decided based on clinical findings. The setting was a specialized trauma hospital. Follow-up included International Knee Documentation Committee forms, radiographs, and the Tegner and Lysholm scores at a mean of 66 months (range, 11-142) after treatment. RESULTS: In all cases, treatment of infection was successful; overall, a mean of 2.2 operations were required. In 7 cases, it was possible to salvage the graft. The Tegner activity level before the knee injury was 6.1 points. At follow-up, the average score was 3.8 points. The postoperative subjective International Knee Documentation Committee score averaged 64. The mean Lysholm score was 65.6. On clinical examination, a mean extension deficit of 3 degrees and a mean maximum flexion of 120 degrees were found. In the single-legged hop test, a mean capacity of 63% compared with the uninjured side was measured. CONCLUSION: The described treatment regimen gives reliable results for this complication. There were no recurrences of septic arthritis or bone infection. Early infection can be managed arthroscopically with satisfactory results regarding the treatment of infection. In advanced or chronic infection, a more radical approach seems favorable. Results in these cases are overall only fair compared with patients with an uncomplicated anterior cruciate ligament reconstruction. [ABSTRACT FROM AUTHOR]

The symbiotic fungus Paxillus involutus serves a critical role in maintaining forest ecosystems, which are carbon sinks of global importance. P. involutus produces involutin and other 2,5-diarylcyclopentenone pigments that presumably assist in the oxidative degradation of lignocellulose via Fenton chemistry. Their precise biosynthetic pathways, however, remain obscure. Using a combination of biochemical, genetic, and transcriptomic analyses, in addition to stable-isotope labeling with synthetic precursors, we show that atromentin is the key intermediate. Atromentin is made by tridomain synthetases of high similarity: InvA1, InvA2, and InvA5. An inactive atromentin synthetase, InvA3, gained activity after a domain swap that replaced its native thioesterase domain with that of InvA5. The found degree of multiplex biosynthetic capacity is unprecedented with fungi, and highlights the great importance of the metabolite for the producer., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Vaccination against the ubiquitous parasite Toxoplasma gondii would provide the most efficient prevention against toxoplasmosis-related congenital, brain and eye diseases in humans. We investigated the immune response elicited by pathogen-specific glycosylphosphatidylinositol (GPI) glycoconjugates using carbohydrate microarrays in a BALB/c mouse model. We further examined the protective properties of the glycoconjugates in a lethal challenge model using the virulent T. gondii RH strain. Upon immunization, mice raised antibodies that bind to the respective GPIs on carbohydrate microarrays, but were mainly directed against an unspecific GPI epitope including the linker. The observed immune response, though robust, was unable to provide protection in mice when challenged with a lethal dose of viable tachyzoites. We demonstrate that anti-GPI antibodies raised against the here described semi-synthetic glycoconjugates do not confer protective immunity against T. gondii in BALB/c mice., (© The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Mesenchymal stem cells (MSC) have the potential to differentiate into multiple cell lineages and their therapeutic potential has become obvious. In the liver, MSC are represented by stellate cells which have the potential to differentiate into hepatocytes after stimulation with growth factors. Since bile acids can promote liver regeneration, their influence on liver-resident and bone marrow-derived MSC was investigated. Physiological concentrations of bile acids such as tauroursodeoxycholic acid were able to initiate hepatic differentiation of MSC via the farnesoid X receptor and transmembrane G-protein-coupled bile acid receptor 5 as investigated with knockout mice. Notch, hedgehog, transforming growth factor-β/bone morphogenic protein family and non-canonical Wnt signalling were also essential for bile acid-mediated differentiation, whereas β-catenin-dependent Wnt signalling was able to attenuate this process. Our findings reveal bile acid-mediated signalling as an alternative way to induce hepatic differentiaion of stem cells and highlight bile acids as important signalling molecules during liver regeneration.

ZG16p is a soluble mammalian lectin that interacts with mannose and heparan sulfate. Here we describe detailed analysis of the interaction of human ZG16p with mycobacterial phosphatidylinositol mannosides (PIMs) by glycan microarray and NMR. Pathogen-related glycan microarray analysis identified phosphatidylinositol mono- and di-mannosides (PIM1 and PIM2) as novel ligand candidates of ZG16p. Saturation transfer difference (STD) NMR and transferred NOE experiments with chemically synthesized PIM glycans indicate that PIMs preferentially interact with ZG16p by using the mannose residues. The binding site of PIM was identified by chemical-shift perturbation experiments with uniformly (15)N-labeled ZG16p. NMR results with docking simulations suggest a binding mode of ZG16p and PIM glycan; this will help to elucidate the physiological role of ZG16p., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Background and Aims: Hepatic stellate cells (HSC), which can participate in liver regeneration and fibrogenesis, have recently been identified as liver-resident mesenchymal stem cells. During their activation HSC adopt a myofibroblast-like phenotype accompanied by profound changes in the gene expression profile. DNA methylation changes at single genes have been reported during HSC activation and may participate in the regulation of this process, but comprehensive DNA methylation analyses are still missing. The aim of the present study was to elucidate the role of DNA methylation during in vitro activation of HSC., Methods and Results: The analysis of DNA methylation changes by antibody-based assays revealed a strong decrease in the global DNA methylation level during culture-induced activation of HSC. To identify genes which may be regulated by DNA methylation, we performed a genome-wide Methyl-MiniSeq EpiQuest sequencing comparing quiescent and early culture-activated HSC. Approximately 400 differentially methylated regions with a methylation change of at least 20% were identified, showing either hypo- or hypermethylation during activation. Further analysis of selected genes for DNA methylation and expression were performed revealing a good correlation between DNA methylation changes and gene expression. Furthermore, global DNA demethylation during HSC activation was investigated by 5-bromo-2-deoxyuridine assay and L-mimosine treatment showing that demethylation was independent of DNA synthesis and thereby excluding a passive DNA demethylation mechanism., Conclusions: In summary, in vitro activation of HSC initiated strong DNA methylation changes, which were associated with gene regulation. These results indicate that epigenetic mechanisms are important for the control of early HSC activation. Furthermore, the data show that global DNA demethylation during activation is based on an active DNA demethylation mechanism.

The current clinical management of TB is complicated by the lack of suitable diagnostic tests that can be employed in infrastructure and resource poor regions. The mannose-capped form of lipoarabinomannan (ManLAM) is unique to the surface envelope of slow-growing, pathogenic mycobacteria such as M.tuberculosis (M.tb) and facilitates passive invasion of mononuclear phagocytes. The detection of this virulence factor in urine, sputum and serum has engendered interest in its employment as a biomarker for M.tb infection. In this study, we utilize a subtractive screening methodology to engineer the first high affinity recombinant antibody (My2F12) with exquisite specificity for the α1-2 mannose linkages enriched in ManLAM from M.tb. My2F12 binds to pathogenic mycobacterial species but not fast growing non-pathogenic species. Testing on matched urine and serum samples from TB patients indicates that My2F12 works in patient cohorts missed by other diagnostic methodologies.

Antibiotic-resistant Gram-negative bacteria are an increasing threat to human health. Strategies to restore antibiotic efficacy include targeting multidrug efflux pumps by competitive efflux pump inhibitors. These could be derived from natural substrates of these efflux systems. In this work, we aimed to elucidate the natural substrates of the clinically relevant Mex efflux pumps of Pseudomonas aeruginosa by an untargeted metabolomic approach. We constructed a PA14 mutant, genetically deleted in the major multidrug efflux pumps MexAB-OprM, MexCD-OprJ, MexXY-OprM, and MexEF-OprN and expressed in this mutant each efflux pump individually from an inducible promoter. Comparative analysis of the exo-metabolomes identified 210 features that were more abundant in the supernatant of efflux pump overexpressors compared to the pump-deficient mutant. Most of the identified features were efflux pump specific, while only a few were shared among several Mex pumps. We identified by-products of secondary metabolites as well as signaling molecules. Supernatants of the pump-deficient mutant also showed decreased accumulation of fatty acids, including long chain homoserine lactone quorum sensing molecules. Our data suggests that Mex efflux pumps of P. aeruginosa appear to have dedicated roles in extruding signaling molecules, metabolic by-products, as well as oxidized fatty acids. These findings represent an interesting starting point for the development of competitive efflux pump inhibitors. [ABSTRACT FROM AUTHOR]

Natural cyclic peptides, a diverse class of bioactive compounds, have been isolated from various natural sources and are renowned for their extensive structural variability and broad spectrum of medicinal properties. Over 40 cyclic peptides or their derivatives are currently approved as medicines, underscoring their significant therapeutic potential. These compounds are employed in diverse roles, including antibiotics, antifungals, antiparasitics, immune modulators, and anti-inflammatory agents. Their unique ability to combine high specificity with desirable pharmacokinetic properties makes them valuable tools in addressing unmet medical needs, such as combating drug-resistant pathogens and targeting challenging biological pathways. Due to the typically low concentrations of cyclic peptides in nature, effective synthetic strategies are indispensable for their acquisition, characterization, and biological evaluation. Cyclization, a critical step in their synthesis, enhances metabolic stability, bioavailability, and receptor binding affinity. Advances in synthetic methodologies—such as solid-phase peptide synthesis (SPPS), chemoenzymatic approaches, and orthogonal protection strategies—have transformed cyclic peptide production, enabling greater structural complexity and precision. This review compiles recent progress in the total synthesis and biological evaluation of natural cyclic peptides from 2017 onward, categorized by cyclization strategies: head-to-tail; head-to-side-chain; tail-to-side-chain; and side-chain-to-side-chain strategies. Each account includes retrosynthetic analyses, synthetic advancements, and biological data to illustrate their therapeutic relevance and innovative methodologies. Looking ahead, the future of cyclic peptides in drug discovery is bright. Emerging trends, including integrating computational tools for rational design, novel cyclization techniques to improve pharmacokinetic profiles, and interdisciplinary collaboration among chemists, biologists, and computational scientists, promise to expand the scope of cyclic peptide-based therapeutics. These advancements can potentially address complex diseases and advance the broader field of biological drug development. [ABSTRACT FROM AUTHOR]

There are still several viral infections affecting a considerable number of the world's population, causing thousands of deaths each year. There are no drugs available for most viral infections and for many not even a vaccine. The marine kingdom is characterized by a huge chemical diversity; however, there is currently on the market only one drug derived from the sea with antiviral properties, called Ara-A. In the current study, we used a solid phase extraction method (SPE) to obtain pre-purified fractions from Diacronema lutheri raw extracts. We tested both raw extracts and fractions against enveloped and non-enveloped viruses. Results showed an antiviral activity of fraction C of D. lutheri against the herpes simplex virus type 1 (HSV-1 strain SC16). Liquid chromatography coupled with untargeted high-resolution tandem mass spectrometry (LC-HRMS2) were employed to chart the metabolite distribution in all SPE fractions and pinpoint molecular families unique (or almost unique) to the bioactive fraction. Sulfoquinovosyl di- and monoacylglycerols (SQDGs and SQMGs) and di- and monogalactosyl monoacylglycerols (DGMGs and MGMGs) represent the largest groups of compounds in fraction C and they are likely responsible for the antiviral properties of this fraction. [ABSTRACT FROM AUTHOR]

The existing literature on environmentally responsible behavior in tourists focuses primarily on the factors that influence this behavior, such as tourists' attitudes and negative feelings. However, the intrinsic benefits of conservation for individual and societal well-being are often overlooked. Under the theoretical lens of self-expansion theory, this study examined the influence of Chinese tourists' tourism autobiographical memory on their environmentally responsible behavior using a questionnaire survey (N = 434) with partial least squares structural equation modeling. The result attested that tourists' self-expansion and psychological richness serially mediate the association between their tourism autobiographical memory and environmentally responsible behavior as a tourist. In addition, the implicit theories of personality moderate the prediction of tourist autobiographical memory on self-expansion. The results provide an additional explanation for environmentally responsible behavior in tourists, with practical implications for marketers and operators in the industry. [ABSTRACT FROM AUTHOR]

Current climate change, particularly ocean warming, will induce shifts in marine species distribution and composition, affecting the marine food web and, thus, trophic interactions. Analyses of the stable isotopes 13C and 15N are commonly used to detect trophic markers for food web analyses. With the current standard methods used in food web ecology, it is still challenging to identify potential changes in the uptake and utilization of trophic markers. In this work, we present a 13C-enrichment analysis by NMR spectroscopy to track the uptake and utilization of dietary carbon in a simple laboratory experiment of a primary producer and its consumer (algae and bivalve). In particular, we tested the hypothesis of a temperature-dependent use of dietary carbon by tracing the incorporation of 13C-atoms. Unicellular phytoplankton, Phaeodactilum tricornutum , was reared in a medium containing 13C-labeled bicarbonate. The accompanying 13C-NMR spectra of labeled P. tricornutum showed a specific profile of 13C-labeled compounds, including typical trophic markers such as the polyunsaturated omega-3 fatty acid eicosapentaenoic acid (EPA). Afterwards, 13C-labeled P. tricornutum was fed to King scallops, Pecten maximus , kept at two different temperatures (15°C and 20°C). Tissue-specific NMR spectra of P. maximus revealed elevated 13C-NMR signals, particularly of the fatty acid EPA in the digestive gland, which was not evident in muscle tissue. The comparison between the two temperatures indicated a change in trophic markers. At the higher temperature, less unsaturated fatty acids were detected in the digested gland, but increased 13C-labels in sugars were detected in the adductor muscle. This might indicate a change in the uptake and utilization of the trophic marker EPA in P. maximus due to a shift in energy conversion from favored beta-oxidation at colder temperatures to conversion from carbohydrates in the warmth. Our approach indicates that besides the accumulation of trophic markers, their incorporation and conversion are additional important factors for the reliable interpretation of trophic linkages under climate change. [ABSTRACT FROM AUTHOR]

Background and Purpose: Esophageal cancer-related gene-4 (ECRG4) participate in inflammation process and can interact with the innate immunity complex TLR4-MD2-CD14 on human granulocytes. In addition, ECRG4 participate in modulation of ion channel function and electrical activity of cardiomyocytes. However, the exact mechanism is unknown. This study aimed to test our hypothesis that ECRG4 contributes to inflammation-induced ion channel dysfunctions in cardiomyocytes. Methods: Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) generated from three donors were treated with lipopolysaccharide (LPS) to establish an endotoxin-induced inflammatory model. Immunostaining, real-time PCR, and patch-clamp techniques were used for the study. Results: ECRG4 was detected in hiPSC-CMs at different differentiation time. LPS treatment increased ECRG4 expression in hiPSC-CMs. Knockdown of ECRG4 decreased the expression level of Toll-Like-Receptor 4 (TLR4, a LPS receptor) and its associated genes and inflammatory cytokines. Furthermore, ECRG4 knockdown shortened the action potential duration (APD) and intercepted LPS-induced APD prolongation by enhancing ISK (small conductance calcium-activated K channel current) and attenuating INCX (Na/Ca exchanger current). Overexpression of ECRG4 mimicked LPS effects on ISK and INCX, which could be prevented by NFκB signaling blockers. Conclusion: This study demonstrated that LPS effects on cardiac ion channel function were mediated by the upregulation of ECRG4, which affects NFκB signaling. Our findings support the roles of ECRG4 in inflammatory responses and the ion channel dysfunctions induced by LPS challenge. [ABSTRACT FROM AUTHOR]

Hepatic stellate cells are mainly known for their contribution to fibrogenesis in chronic liver diseases, but their identity and function in normal liver remain unclear. They were recently identified as liver-resident mesenchymal stem cells (MSCs), which can differentiate not only into adipocytes and osteocytes, but also into liver epithelial cells such as hepatocytes and bile duct cells as investigated in vitro and in vivo. During hepatic differentiation, stellate cells and other MSCs transiently develop into liver progenitor cells with epithelial characteristics before hepatocytes are established. Transplanted stellate cells from the liver and pancreas are able to contribute to liver regeneration in stem cell-based liver injury models and can also home into the bone marrow, which is in line with their classification as MSCs. There is experimental evidence that bile acids support liver regeneration and are able to activate signaling pathways in hepatic stellate cells. For this reason, it is important to analyze the influence of bile acids on developmental fate decisions of hepatic stellate cells and other MSC populations., (2015 S. Karger AG, Basel.)

Around 2 billion people worldwide are infected with the apicomplexan parasite Toxoplasma gondii which induces a variety of medical conditions. For example, primary infection during pregnancy can result in fetal death or mental retardation of the child. Diagnosis of acute infections in pregnant women is challenging but crucially important as the drugs used to treat T. gondii infections are potentially harmful to the unborn child. Better, faster, more reliable, and cheaper means of diagnosis by using defined antigens for accurate serological tests are highly desirable. Synthetic pathogen-specific glycosylphosphatidylinositol (GPI) glycan antigens are diagnostic markers and have been used to distinguish between toxoplasmosis disease states using human sera., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Retinoid-storing hepatic stellate cells (HSCs) have recently been described as a liver-resident mesenchymal stem cell (MSC) population; however, it is not clear whether these cells contribute to liver regeneration or serve as a progenitor cell population with hepatobiliary characteristics. Here, we purified HSCs with retinoid-dependent fluorescence-activated cell sorting from eGFP-expressing rats and transplanted these GFP(+) HSCs into wild-type (WT) rats that had undergone partial hepatectomy in the presence of 2-acetylaminofluorene (2AAF) or retrorsine, both of which are injury models that favor stem cell-based liver repair. Transplanted HSCs contributed to liver regeneration in host animals by forming mesenchymal tissue, progenitor cells, hepatocytes, and cholangiocytes and elevated direct bilirubin levels in blood sera of GUNN rats, indicating recovery from the hepatic bilirubin-handling defect in these animals. Transplanted HSCs engrafted within the bone marrow (BM) of host animals, and HSC-derived cells were isolated from BM and successfully retransplanted into new hosts with injured liver. Cultured HSCs transiently adopted an expression profile similar to that of progenitor cells during differentiation into bile acid-synthesizing and -transporting hepatocytes, suggesting that stellate cells represent a source of liver progenitor cells. This concept connects seemingly contradictory studies that favor either progenitor cells or MSCs as important players in stem cell-based liver regeneration.

Histone deacetylase inhibitors (HDIs) specifically affect cancer cells by inducing cell cycle arrest, activate apoptotic pathways and re-activate epigenetically silenced tumor suppressor genes, but their pleiotropic mode of action is not fully understood. Despite the clinical effects of HDIs in the treatment of hematological malignancies, their potency against solid tumors is still unclear. We investigated the effects and mechanisms of HDI action in colorectal carcinoma cell lines with an activated Wnt signaling pathway, which is implicated in different aspects of tumorigenesis, including cell proliferation, apoptosis, angiogenesis and metastasis. We assessed the effects of HDI treatment in colorectal carcinoma cell lines by measuring histone hyperacetylation, cell viability and expression of Wnt target genes. Upon treatment with HDIs of the hydroxamate class, we found attenuation of Wnt signaling with concomitant induction of apoptosis and colorectal cancer cell death. Strikingly, the effects of HDIs on Wnt signaling were independent of histone hyperacetylation, thus we investigated the role of non-histone target proteins of histone deacetylases (HDACs). The compounds TSA and SAHA induced a rapid proteasome-dependent depletion of the Wnt transcription factor TCF7L2, which may be mediated by inhibition of HDAC 6 and 10. Our findings provide a molecular rationale for the use of HDIs against colorectal carcinomas with activated Wnt signaling.

Identification of carbohydrate sequences that determine affinity to specific chemokines is a critical step for strategies to interfere with chemokine-mediated leukocyte trafficking. Here, we first characterized the development of allergic asthma in Tie2-dependent and inducible Ext1-knockout (Tie2-Ext1(iKO)) mice. We showed that heparan sulfate is essential for leukocyte recruitment in the peribronchial region and bronchoalveolar lavage fluid (BALF), and is crucial for induction of airway hyperresponsiveness. Our glycan microarray showed a unique affinity profile of chemokine CCL20 to substructures of heparin and heparin-like oligo/di/monosaccharides. Among them, we identified a synthetic and not naturally occurring monosaccharide, 2,4-O-di-sulfated iduronic acid (Di-S-IdoA), as a potential inhibitor for CCL20-heparan sulfate interaction. Mice injected with Di-S-IdoA via tail vain or nasal inhalation showed attenuated leukocyte recruitment into inflammatory sites and BALF. These results demonstrate a critical role of chemokine-heparan sulfate interaction in the asthma development and Di-S-IdoA as a potential drug for asthma treatment.