Cationic polyamines inhibit anthrax lethal factor protease

BACKGROUND: Anthrax is a human disease that results from infection by the bacteria, Bacillus anthracis and has recently been used as a bioterrorist agent. Historically, this disease was associated with Bacillus spore exposure from wool or animal carcasses. While current vaccine approaches (targeted against the protective antigen) are effective for prophylaxis, multiple doses must be injected. Common antibiotics that block the germination process are effective but must be administered early in the infection cycle. In addition, new therapeutics are needed to specifically target the proteolytic activity of lethal factor (LF) associated with this bacterial infection. RESULTS: Using a fluorescence-based assay to identify and characterize inhibitors of anthrax lethal factor protease activity, we identified several chemically-distinct classes of inhibitory molecules including polyamines, aminoglycosides and cationic peptides. In these studies, spermine was demonstrated for the first time to inhibit anthrax LF with a K(i )value of 0.9 ± 0.09 μM (mean ± SEM; n = 3). Additional linear polyamines were also active as LF inhibitors with lower potencies. CONCLUSION: Based upon the studies reported herein, we chose linear polyamines related to spermine as potential lead optimization candidates and additional testing in cell-based models where cell penetration could be studied. During our screening process, we reproducibly demonstrated that the potencies of certain compounds, including neomycin but not neamine or spermine, were different depending upon the presence or absence of nucleic acids. Differential sensitivity to the presence/absence of nucleic acids may be an additional point to consider when comparing various classes of active compounds for lead optimization

The impacts of municipal biosolids on some indicators of soil health

The abundance and diversity of soil organisms are considered to be prime indicators of soil health, which has been defined as the capacity of soil to sustain productivity. Municipal biosolids are good sources of N, P and micronutrients for short-term crop production. The long-term impacts of biosolids on indicators of soil health are, however, less well understood. As inputs of organic C, biosolids have potential to increase soil biodiversity and improve soil health. However, because they contain greater concentrations of some metals than receiving soil, there is also potential for biosolids to have regressive effects on soil biodiversity and soil health. We have been studying the impacts of biosolids on arbuscular-mycorrhizal fungi (AMF) and diversity of soil microfauna, as well as nutrient availability, at three sites in the southern interior of BC: (1) irrigated alfalfa, (2) crested wheatgrass, and (3) native range vegetation. We have found that high biosolids application rates (e.g. 60 Mg/ha) can cause slight reductions in diversity of microfauna and colonization of alfalfa roots by AMF, relative to untreated soil. The reduced colonization of alfalfa by AMF appears to be the result of enhanced availability of P. Since uptake of P, Cu and Zn is the primary benefit of AMF to crop plants, the implications of reduced AMF colonization (in response to enhanced P availability) are not yet clear. It is also still unclear if the reduced diversity of micro-fauna is the result of nutrient loading or metals. We hypothesize that the use of biosolids in reclamation projects, where the reference point is degraded soil, is more likely to enhance soil health.Non UBCUnreviewedOthe

Using <i>C</i>. <i>elegans</i> Forward and Reverse Genetics to Identify New Compounds with Anthelmintic Activity

<div><p>Background</p><p>The lack of new anthelmintic agents is of growing concern because it affects human health and our food supply, as both livestock and plants are affected. Two principal factors contribute to this problem. First, nematode resistance to anthelmintic drugs is increasing worldwide and second, many effective nematicides pose environmental hazards. In this paper we address this problem by deploying a high throughput screening platform for anthelmintic drug discovery using the nematode <i>Caenorhabditis elegans</i> as a surrogate for infectious nematodes. This method offers the possibility of identifying new anthelmintics in a cost-effective and timely manner.</p><p>Methods/Principal findings</p><p>Using our high throughput screening platform we have identified 14 new potential anthelmintics by screening more than 26,000 compounds from the Chembridge and Maybridge chemical libraries. Using phylogenetic profiling we identified a subset of the 14 compounds as potential anthelmintics based on the relative sensitivity of <i>C</i>. <i>elegans</i> when compared to yeast and mammalian cells in culture. We showed that a subset of these compounds might employ mechanisms distinct from currently used anthelmintics by testing diverse drug resistant strains of <i>C</i>. <i>elegans</i>. One of these newly identified compounds targets mitochondrial complex II, and we used structural analysis of the target to suggest how differential binding of this compound may account for its different effects in nematodes versus mammalian cells.</p><p>Conclusions/Significance</p><p>The challenge of anthelmintic drug discovery is exacerbated by several factors; including, 1) the biochemical similarity between host and parasite genomes, 2) the geographic location of parasitic nematodes and 3) the rapid development of resistance. Accordingly, an approach that can screen large compound collections rapidly is required. <i>C</i>. <i>elegans</i> as a surrogate parasite offers the ability to screen compounds rapidly and, equally importantly, with specificity, thus reducing the potential toxicity of these compounds to the host and the environment. We believe this approach will help to replenish the pipeline of potential nematicides.</p></div