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Clostridioides difficileis a commensal Gram-positive gut bacterium that causes C. difficile-associated diarrhea. Currently available antibacterial therapeutic treatment options are effective except for the repeated recurrences significantly burdening the health care system and causing mortality. The development of new therapeutic modalities including new effective antibiotics with a low rate of recurrence has been unpredictive and exceedingly challenging, requiring continued profiling of many new classes of antibiotics. Nocathiacins and thiazomycins are a class of thiazolyl peptides exhibiting potent and selective broad-spectrum Gram-positive activity including activity against the anaerobe C. difficile. These compounds showed MIC values of 0.015–0.06 μg/mL against C. difficilewith more than 100–200-fold selectivity versus commensurate Gram-negative Bacteroides fragilis. Nocathiacin I and one of its analogs exhibited potent in vivoefficacy in the gold-standard hamster model of C. difficileinfection, providing 100% protection in this lethal model at 6.25 mg/kg orally twice daily. The efficacy was corroborated by robust reduction of cecum C. difficileburden and proportionate exposure of the compounds in the cecum contents without any systemic absorption. In this paper, details of the results of in vitro, in vivo, pharmacodynamics, and pharmacokinetic studies have been described.

Agroecosystems occupy large areas of the land surface and arable soil food webs are of significant importance for global cycling of carbon (C) and nitrogen (N). In a field experiment we labeled maize plants (Zea maysL.) in 13CO2atmosphere and by K15NO3fertilization. During 25days, the incorporation of 13C and 15N was traced in plant compartments, soil and soil arthropods, as well as 13C in microbial phospholipid fatty acids (PLFAs) and nematodes. Highlighting the importance of root-derived resources in agroecosystems, 13C was incorporated into all food web compartments, including microorganisms (PLFAs), nematodes and arthropods. The amount of incorporated 13C (as compared to unlabeled samples) markedly decreased along the food chain with ∆13C decreasing from 500‰ in plant roots and 900‰ in microbial PLFAs, to less than 40‰ in nematodes and arthropods. Incorporation of 13C into fungal PLFAs considerably exceeded that into bacterial PLFAs, highlighting the importance of soil fungi as compared to bacteria in C cycling. Fertilizer-derived 15N uniformly increased with time in plant compartments and soil arthropods, indicating that N is distributed homogeneously in the soil food web. High channeling of both root-derived 13C and fertilizer-derived 15N to higher trophic levels by fungi, and intensive feeding on fungi by soil animals highlight the central role of saprotrophic fungi in C and nutrient fluxes in soil food webs of arable ecosystems.

Ribonucleoprotein (RNP) granules are important posttranscriptional regulators of messenger RNA (mRNA) fate. Several types of RNPgranules specifically regulate gene expression during development of multicellular organisms and are commonly referred to as germ granules. The function of germ granules is not entirely understood and probably diverse, but it is generally agreed that one main function is posttranscriptional regulation of gene expression during early development, when transcription is silent. One example is the translational repression of maternally derived mRNAsin oocytes. Here, I hope to show that the need for regulation of gene expression by RNPgranules is not restricted to animal development, but plays an equally important role during the development of pathogenic protozoa. Apicomplexaand Trypanosomatidaehave complex life cycles with frequent host changes. The need to quickly adapt gene expression to a new environment as well as the ability to suppress translation to survive latencies is critical for successful completion of life cycles. Posttranscriptional gene regulation is not necessarily simpler in protozoa. Apicomplexasurprise with the presence of micro RNA (miRNAs) and upstream open reading frames (µORFs). Trypanosomes have an unusually large repertoire of different RNPgranule types. A better understanding of RNPgranules in protozoa may help to gain insight into the evolutionary origin of RNPgranules: Trypanosomes for example have two types of granules with interesting similarities to animal germ granules. WIREs RNA2014, 5:263–284. doi: 10.1002/wrna.1207

Trypanosomes lack many core components of ribonucleoprotein (RNP) granules identified in yeast and humans (e.g., DCP1/2). This study provides evidence for SCD6 being the core RNP granule component in trypanosomes: overexpression induces granules independent of translation, and even when SCD6 is targeted to the nucleus. Granule type and granule number are dependent on the RGG domain.

Infection of certain cell types by HIV results in formation of syncytia. This process can be blocked by antibodies or compounds that prevent interaction of viral envelope protein with host cell receptors. Here the authors describe an automated imaging-based assay for inhibitors of cell-cell fusion mediated by interaction of HIV gp120 with CXCR4 coreceptor. The assay quantifies syncytia formation between U87MG astrocytoma cells constitutively expressing CD4/CXCR4 and morphologically distinct Jurkat T lymphoma cells inducibly expressing HIV env.Each cell type was differentially labeled with vital dyes. Fusion was quantified by measuring size, shape, and color of Jurkat cells and Jurkat-harboring cell syncytia. Dose–response experiments with reference inhibitors AMD 3100 and KRH-1636 yielded potencies consistent with those obtained using standard antiviral assays. This assay complements virus-based infectivity assays for identification of inhibitors of membrane fusion events triggered by interaction of HIV gp120 with host CXCR4.

The therapeutic potential of monoclonal antibodies (MAbs) for treating a variety of severe or life-threatening diseases is high. Although intravenous infusion appears to be the simplest and most obvious mode of administration, it is not applicable in many long-term treatments. It might, however, be advantageously replaced by gene/cell therapies, rendering treatments cost-effective and eliminating the short- and long-term side effects associated with injection of massive doses of antibodies. Grafting of ex vivo genetically modified cells of various types has already been used for in vivo production and systemic delivery of MAbs in mice. However, although sustained for long periods of time, serum levels of ectopic MAbs were low. We show here that in vivo administration to mice of a first-generation adenoviral vector expressing a model MAb also permits achievement of the same goal, but with 100 to 200 times better efficiency that in any other case of gene transfer described thus far. We also investigated for possible anti-idiotypic response against the ectopic MAb. None was detected in the animals expressing the lowest levels of ectopic MAb production; a response was detected among the highest producers. In the latter case, however, the response was low and could not exert any significant neutralizing activity. In conclusion, our work indicates that high levels of circulating ectopic MAb can be obtained on direct in vivo gene transfer without inducing an anti-idiotypic response sufficiently robust to exert a neutralizing effect. This observation is encouraging in the perspective of clinical applications of this technology.

Extracellular factors such as FGF and EGF control various aspects of morphogenesis, patterning and cellular proliferation in both invertebrates and vertebrates. In most systems, it is primarily the distribution of these factors that controls the differential behavior of the responding cells. Here we describe the role of Sprouty in eye development. Sprouty is an extracellular protein that has been shown to antagonize FGF signaling during tracheal branching in Drosophila. It is a novel type of protein with a highly conserved cysteine-rich region. In addition to the embryonic tracheal system, sprouty is also expressed in other tissues including the developing eye imaginal disc, embryonic chordotonal organ precursors and the midline glia. In each of these tissues, EGF receptor signaling is known to participate in the control of the correct number of neurons or glia. We show that, in all three tissues, the loss of sprouty results in supernumerary neurons or glia, respectively. Furthermore, overexpression of sprouty in wing veins and ovarian follicle cells, two other tissues where EGF signaling is required for patterning, results in phenotypes that resemble the loss-of-function phenotypes of Egf receptor. These results suggest that Sprouty acts as an antagonist of EGF as well as FGF signaling pathways. These receptor tyrosine kinase-mediated pathways may share not only intracellular signaling components but also extracellular factors that modulate the strength of the signal.

Drosophila seven-up is an orphan receptor of the steroid receptor family that is required to specify photoreceptor neuron subtypes in the developing compound eye. Expression of seven-up is confined to four of the eight photoreceptor precursors, R3/R4/R1/R6. We show that misexpression of seven-up in any of the other cell types within the developing ommatidium interferes with their differentiation. Each cell type responds differently to seven-up misexpression. For example, ectopic expression in the non-neuronal cone cells using the sevenless promoter/enhancer (sev-svp) causes the cone cells to take on a neuronal identity. Ectopic expression of seven-up in R2/R5 using the rough enhancer (ro-svp) causes these neurons to lose aspects of their photoreceptor subtype identity while remaining neuronal. Each cell type appears to have a different developmental time window that is sensitive to misexpressed seven-up. The temporal order of responsiveness of each cell type to misexpressed seven-up is similar but not identical to the order of neuronal differentiation. This suggests that there are processes of specification that are distinct from the specification to become a photoreceptor neuron. We have identified members of the ras signaling pathway as suppressors of the cone cell to R7 neuron transformation caused by sev-svp. Suppression of the sev-svp phenotype can be achieved by decreasing the gene-dosage of any of the members of the ras-pathway. This suggests that the function of seven-up in the cone cells requires ras signaling. However, a decrease in ras signaling results in enhancement of the phenotype caused by the rosvp transgene. We discuss the relationship between decisions controlled by seven-up and those controlled by ras signaling.

The 5′ ends of most RNAs are chemically modified to enable protection from nucleases. In bacteria, this is often achieved by keeping the triphosphate terminus originating from transcriptional initiation, while most eukaryotic mRNAs and small nuclear RNAs have a 5′→5′ linked N7‐methyl guanosine (m7G) cap added. Several other chemical modifications have been described at RNA 5′ ends. Common to all modifications is the presence of at least one pyrophosphate bond. To enable RNA turnover, these chemical modifications at the RNA 5′ end need to be reversible. Dependent on the direction of the RNA decay pathway (5′→3′ or 3′→5′), some enzymes cleave the 5′→5′ cap linkage of intact RNAs to initiate decay, while others act as scavengers and hydrolyse the cap element of the remnants of the 3′→5′ decay pathway. In eukaryotes, there is also a cap quality control pathway. Most enzymes involved in the cleavage of the RNA 5′ ends are pyrophosphohydrolases, with only a few having (additional) 5′ triphosphonucleotide hydrolase activities. Despite the identity of their enzyme activities, the enzymes belong to four different enzyme classes. Nudix hydrolases decap intact RNAs as part of the 5′→3′ decay pathway, DXO family members mainly degrade faulty RNAs, members of the histidine triad (HIT) family are scavenger proteins, while an ApaH‐like phosphatase is the major mRNA decay enzyme of trypanosomes, whose RNAs have a unique cap structure. Many novel cap structures and decapping enzymes have only recently been discovered, indicating that we are only beginning to understand the mechanisms of RNA decapping. This article is categorized under: RNA Turnover and Surveillance > Turnover/Surveillance MechanismsRNA Turnover and Surveillance > Regulation of RNA StabilityRNA Processing > Capping and 5′ End Modifications Enzymes that hydrolyse the 5′ end of RNAs belong to four different enzyme classes: Nudix hydrolases, histidine triad (HIT) proteins, DXO proteins, and ApaH‐like phosphatases.

Methicillin-resistant Staphylococcus aureusinfection can be treated effectively by combining a β-lactam antibiotic with a drug that targets FtsZ.