Loss of the Mono-ADP-ribosyltransferase,Tiparp, Increases Sensitivity to Dioxin-induced Steatohepatitis and Lethality

The aryl hydrocarbon receptor (AHR) mediates the toxic effects of the environmental contaminant dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin; TCDD). Dioxin causes a range of toxic responses, including hepatic damage, steatohepatitis, and a lethal wasting syndrome; however, the mechanisms are still unknown. Here, we show that the loss of TCDD-inducible poly(ADP-ribose) polymerase (Tiparp), an ADP-ribosyltransferase and AHR repressor, increases sensitivity to dioxin-induced toxicity, steatohepatitis, and lethality. Tiparp^−/− mice given a single injection of 100 μg/kg dioxin did not survive beyond day 5; all Tiparp^+/+ mice survived the 30-day treatment. Dioxin-treated Tiparp^−/− mice exhibited increased liver steatosis and hepatotoxicity. Tiparp ADP-ribosylated AHR but not its dimerization partner, the AHR nuclear translocator, and the repressive effects of TIPARP on AHR were reversed by the macrodomain containing mono-ADP-ribosylase MACROD1 but not MACROD2. These results reveal previously unidentified roles for Tiparp, MacroD1, and ADP-ribosylation in AHR-mediated steatohepatitis and lethality in response to dioxin.     

Inhibition of Neisseria gonorrhoeae Type II Topoisomerases by the Novel Spiropyrimidinetrione AZD0914

We characterized the inhibition of Neisseria gonorrhoeae type II topoisomerases gyrase and topoisomerase IV by AZD0914 (AZD0914 will be henceforth known as ETX0914 (Entasis Therapeutics)), a novel spiropyrimidinetrione antibacterial compound that is currently in clinical trials for treatment of drug-resistant gonorrhea. AZD0914 has potent bactericidal activity against N. gonorrhoeae, including multidrug-resistant strains and key Gram-positive, fastidious Gram-negative, atypical, and anaerobic bacterial species (Huband, M. D., Bradford, P. A., Otterson, L. G., Basrab, G. S., Giacobe, R. A., Patey, S. A., Kutschke, A. C., Johnstone, M. R., Potter, M. E., Miller, P. F., and Mueller, J. P. (2014) In Vitro Antibacterial Activity of AZD0914: A New Spiropyrimidinetrione DNA Gyrase/Topoisomerase Inhibitor with Potent Activity against Gram-positive, Fastidious Gram-negative, and Atypical Bacteria. Antimicrob. Agents Chemother. 59, 467–474). AZD0914 inhibited DNA biosynthesis preferentially to other macromolecules in Escherichia coli and induced the SOS response to DNA damage in E. coli. AZD0914 stabilized the enzyme-DNA cleaved complex for N. gonorrhoeae gyrase and topoisomerase IV. The potency of AZD0914 for inhibition of supercoiling and the stabilization of cleaved complex by N. gonorrhoeae gyrase increased in a fluoroquinolone-resistant mutant enzyme. When a mutation, conferring mild resistance to AZD0914, was present in the fluoroquinolone-resistant mutant, the potency of ciprofloxacin for inhibition of supercoiling and stabilization of cleaved complex was increased greater than 20-fold. In contrast to ciprofloxacin, religation of the cleaved DNA did not occur in the presence of AZD0914 upon removal of magnesium from the DNA-gyrase-inhibitor complex. AZD0914 had relatively low potency for inhibition of human type II topoisomerases α and β.     

R-isomers of Arg-Gly-Asp (RGD) mimics as potent alphavbeta3 inhibitors

The integrin alpha(v)beta(3), vitronectin receptor, is expressed in a number of cell types and has been shown to mediate adhesion of osteoclasts to bone matrix, vascular smooth muscle cell migration, and angiogenesis. We recently disclosed the discovery of a tripeptide Arg-Gly-Asp (RGD) mimic, which has been shown to be a potent inhibitor of the integrin alpha(v)beta(3) and has excellent anti-angiogenic properties including its suppression of tumor growth in animal models. In other investigations involving RGD mimics, only compounds containing the S-isomers of the beta-amino acids have been shown to be potent. We were surprised to find the potencies of analogs containing enantiomerically pure S-isomers of beta-amino acids which were only marginally better than the corresponding racemic mixtures. We therefore synthesized RGD mimics containing R-isomers of beta-amino acids and found them to be relatively potent inhibitors of alpha(v)beta(3). One of the compounds was examined in tumor models in mice and has been shown to significantly reduce the rate of growth and the size of tumors.     

Neural network analyses of infrared spectra for classifying cell wall architectures

About 10% of plant genomes are devoted to cell wall biogenesis. Our goal is to establish methodologies that identify and classify cell wall phenotypes of mutants on a genome-wide scale. Toward this goal, we have used a model system, the elongating maize (Zea mays) coleoptile system, in which cell wall changes are well characterized, to develop a paradigm for classification of a comprehensive range of cell wall architectures altered during development, by environmental perturbation, or by mutation. Dynamic changes in cell walls of etiolated maize coleoptiles, sampled at one-half-d intervals of growth, were analyzed by chemical and enzymatic assays and Fourier transform infrared spectroscopy. The primary walls of grasses are composed of cellulose microfibrils, glucuronoarabinoxylans, and mixed-linkage (1 --> 3),(1 --> 4)-beta-D-glucans, together with smaller amounts of glucomannans, xyloglucans, pectins, and a network of polyphenolic substances. During coleoptile development, changes in cell wall composition included a transient appearance of the (1 --> 3),(1 --> 4)-beta-D-glucans, a gradual loss of arabinose from glucuronoarabinoxylans, and an increase in the relative proportion of cellulose. Infrared spectra reflected these dynamic changes in composition. Although infrared spectra of walls from embryonic, elongating, and senescent coleoptiles were broadly discriminated from each other by exploratory principal components analysis, neural network algorithms (both genetic and Kohonen) could correctly classify infrared spectra from cell walls harvested from individuals differing at one-half-d interval of growth. We tested the predictive capabilities of the model with a maize inbred line, Wisconsin 22, and found it to be accurate in classifying cell walls representing developmental stage. The ability of artificial neural networks to classify infrared spectra from cell walls provides a means to identify many possible classes of cell wall phenotypes. This classification can be broadened to phenotypes resulting from mutations in genes encoding proteins for which a function is yet to be described.     

Contrasting effects of IGF binding protein-3 expression in mammary tumor cells and the tumor microenvironment

IGFBP-3 has both stimulatory and inhibitory effects on cancer progression. The growth of EO771 mammary carcinoma cells as syngeneic tumors in C57BL/6 mice is reduced in Igfbp3-null (BP3KO) mice, suggesting that systemic IGFBP-3 enhances tumor progression. In this study we assessed the growth of EO771 cells expressing human IGFBP-3 in BP3KO mice. Cells expressing hIGFBP-3 showed decreased proliferation in vitro and increased levels of IGF-1 receptor (IGF1R) protein but not mRNA, consistent with sequestration of endogenous IGF by IGFBP-3. The growth rate of these cells was restored by exposure to IGF-1 or analogues with reduced affinity for IGFBP-3 (long Arg³-IGF-1) or IGF1R (Leu²⁴-IGF-1). In EO771 cells implanted orthotopically into mice, hIGFBP-3 expression by the cells inhibited tumor establishment in BP3KO but not wild-type mice. For tumors that successfully established, final weight was not affected significantly by hIGFBP-3 expression. However, final tumor weight was inversely related to intratumoral T cell counts, and sera from BP3KO mice with tumors showed low-titer immunoreactivity against IGFBP-3. The contrasting effects on tumor establishment and progression of IGFBP-3 expressed by mammary carcinoma cells, compared to systemic stromal and circulating IGFBP-3, highlights the complexity of growth regulation by IGFBP-3 in mammary tumors.     

Influence of buffalograss management practices on Western chinch bug and its beneficial arthropods

A 2-yr study was conducted to document the influence of selected buffalograss, Buchlo? dactyloides (Nuttall) Engelmann, management practices (three mowing heights and five nitrogen levels) on the seasonal abundance of the western chinch bug, Blissus occiduus Barber (Heteroptera: Lygaeidae), and its beneficial arthropods. Vacuum, pitfall, and sticky traps samples were collected every 14 d from the middle of May through October from western chinch bug-resistant ('Prestige') and -susceptible ('378') buffalograss management plots. In total, 27,374 and 108,908 western chinch bugs were collected in vacuum and pitfall traps, respectively. More than 78% of all western chinch bugs were collected from the highly susceptible buffalograss 378. Significantly more bigeyed bugs (Geocoridae: Geocoris spp.) were collected from the 378 buffalograsss management plots than the Prestige plots. In contrast, buffalograss cultivar had little influence on the abundance of other beneficial arthropods collected. Statistically, western chinch bugs were least abundant at the lowest mowing height (2.5 cm) and increased in abundance with increasing fertility. Numerically, however, differences among management levels on western chinch bug abundance were minimal. Numerous beneficial arthropods were collected from buffalograss management plots, including spiders, predatory ants, ground beetles (Carabidae), rove beetles (Staphylinidae), bigeyed bugs, and several species of hymenopterous parasitoids. In general, beneficial arthropods were essentially unaffected by either mowing height or nitrogen level. Scelionid wasps represented 66.3% of the total parasitoids collected. The total number of scelionid wasps collected among the three mowing heights and five nitrogen levels were approximately equal.     

“Spider Monkey Cotton”: Bridging Waiwai and Scientific Ontologies to Characterize Spider Monkey (Ateles paniscus) Filariasis in the Konashen Community Owned Conservation Area,Guyana

International Journal of Primatology - Zoonotic disease risk is greatly influenced by cultural practices and belief systems. Yet, few studies have investigated how different ways of knowing are...     

Can Co-Grazing Waterfowl Reduce Brainworm Risk for Goats Browsing in Natural Areas?

Goats browsing in woodlands, whether for livestock production goals or vegetation management (e.g., targeted grazing to control invasive plants), are at risk of meningeal worm (Parelaphostrongylus tenuis) infection. Indeed, up to 25% incidence has been observed in goats employed in vegetation management. Infection, which occurs via the consumption of an infected gastropod intermediate host, is potentially deadly in goats. We experimentally tested whether co-grazing with waterfowl could reduce goats’ exposure via waterfowl consumption of gastropods. Gastropods were sampled in a deciduous woodland before and after the addition of goats alone, goats and waterfowl, or a control with no animal addition. We found that goats browsing on their own increased the abundance of P. tenuis intermediate hosts; however, when goats co-grazed with waterfowl, these increases were not observed. Importantly, waterfowl did not significantly affect overall gastropod abundance, richness, or diversity. Thus, waterfowl co-grazing may effectively reduce goat contact with infectious gastropods without detrimentally affecting the gastropod community. While co-grazing goats with waterfowl may decrease their P. tenuis exposure risk, additional research is needed to confirm whether waterfowl can actually lower P. tenuis incidence.

     

Exposure to Leishmania braziliensis Triggers Neutrophil Activation and Apoptosis

BackgroundNeutrophils are the first line of defense against invading pathogens and are rapidly recruited to the sites of Leishmania inoculation. During Leishmania braziliensis infection, depletion of inflammatory cells significantly increases the parasite load whereas co-inoculation of neutrophils plus L. braziliensis had an opposite effect. Moreover, the co-culture of infected macrophages and neutrophils also induced parasite killing leading us to ask how neutrophils alone respond to an L. braziliensis exposure. Herein we focused on understanding the interaction between neutrophils and L. braziliensis, exploring cell activation and apoptotic fate.ConclusionsWe show that L. braziliensis induces neutrophil recruitment in vivo and that neutrophils exposed to the parasite in vitro respond through activation and release of inflammatory mediators. This outcome may impact on parasite elimination, particularly at the early stages of infection.