Patch residence time and patch preference of the predatory mite <Emphasis Type="Italic">Amblyseius swirskii</Emphasis> in relation to prey diversity

Patch-related behaviour of a generalist predator may be influenced by patch prey diversity and result in more time being spent in patches with more than one prey species to increase the benefits of mixed diet. To examine if generalist predators are able to discern differences in prey diversity in and among patches, we examined the patch-related behaviour of the predatory mite Amblyseius swirskii (Athias-Henriot) (Acari: Phytoseiidae). Three lab experiments using clean, single-prey or mixed-prey patches were conducted, using whiteflies and spider mites as prey. The experiments were: (1) patch leaving tendency and residence time in absence and (2) presence of another patch, (3) patch preference. A. swirskii recognized prey-inhabited patches from a distance and showed a preference for mixed-prey patches over single-prey patches. The patch-related behaviour of A. swirskii, which seems tuned to exploiting the fitness gains of a mixed diet, is influenced by both local and distant cues.     

Essential Oils as Biocides for the Control of Fungal Infections and Devastating Pest (Tuta absoluta) of Tomato (Lycopersicon esculentum Mill.)

Thymus capitatus and Tetraclinis articulata essential oils as well their major components (carvacrol and α‐pinene) were evaluated for their antifungal and insecticidal activities. Both oils showed good in vitro antifungal activity against Fusarium oxysporum, Aspergillus niger, Penicillium sp., Alternaria alternata, and Botrytis cinerea, the fungi causing tomato rot. In vivo results indicate the efficacies of both essential oils and carvacrol of reduce postharvest fungal pathogens, such as B. cinerea and Al. alternata that are responsible of black and gray rot of tomato fruit. Disease incidence of Al. alternata and B. cinerea decreased on average from 55% to 80% with essential oil of Th. capitatus and pure carcvacrol, while Te. articulata essential oil exhibited inhibition of fungal growth of 55% and 25% against Al. alternata and B. cinerea, respectively, with concentration of 0.4 μl/l air. The insecticidal activity of Th. capitatus and Te. articulata essential oils exhibited also a good insecticidal activity. At the concentration of 0.2 μl/ml air, the oils caused mortality over 80% for all larval stages of Tuta absoluta and 100% mortality for the first‐instar after 1.5 h only of exposure. α‐Pinene presented lower insecticidal and antifungal activities compared to essential oils of Th. capitatus, Te. articulata and pure carvacrol. Thus, these essential oils can be used as a potential source to develop control agents to manage some of the main pests and fungal diseases of tomato crops.     

Delivery of siRNA to the mouse brain by systemic injection of targeted exosomes

To realize the therapeutic potential of RNA drugs, efficient, tissue-specific and nonimmunogenic delivery technologies must be developed. Here we show that exosomes-endogenous nano-vesicles that transport RNAs and proteins-can deliver short interfering (si)RNA to the brain in mice. To reduce immunogenicity, we used self-derived dendritic cells for exosome production. Targeting was achieved by engineering the dendritic cells to express Lamp2b, an exosomal membrane protein, fused to the neuron-specific RVG peptide. Purified exosomes were loaded with exogenous siRNA by electroporation. Intravenously injected RVG-targeted exosomes delivered GAPDH siRNA specifically to neurons, microglia, oligodendrocytes in the brain, resulting in a specific gene knockdown. Pre-exposure to RVG exosomes did not attenuate knockdown, and non-specific uptake in other tissues was not observed. The therapeutic potential of exosome-mediated siRNA delivery was demonstrated by the strong mRNA (60%) and protein (62%) knockdown of BACE1, a therapeutic target in Alzheimer's disease, in wild-type mice.     

Distinct clonal lineages and within-host diversification shape invasive Staphylococcus epidermidis populations

S. epidermidis is a substantial component of the human skin microbiota, but also one of the major causes of nosocomial infection in the context of implanted medical devices. We here aimed to advance the understanding of S. epidermidis genotypes and phenotypes conducive to infection establishment. Furthermore, we investigate the adaptation of individual clonal lines to the infection lifestyle based on the detailed analysis of individual S. epidermidis populations of 23 patients suffering from prosthetic joint infection. Analysis of invasive and colonizing S. epidermidis provided evidence that invasive S. epidermidis are characterized by infection-supporting phenotypes (e.g. increased biofilm formation, growth in nutrient poor media and antibiotic resistance), as well as specific genetic traits. The discriminating gene loci were almost exclusively assigned to the mobilome. Here, in addition to IS256 and SCCmec, chromosomally integrated phages was identified for the first time. These phenotypic and genotypic features were more likely present in isolates belonging to sequence type (ST) 2. By comparing seven patient-matched nasal and invasive S. epidermidis isolates belonging to identical genetic lineages, infection-associated phenotypic and genotypic changes were documented. Besides increased biofilm production, the invasive isolates were characterized by better growth in nutrient-poor media and reduced hemolysis. By examining several colonies grown in parallel from each infection, evidence for genetic within-host population heterogeneity was obtained. Importantly, subpopulations carrying IS insertions in agrC, mutations in the acetate kinase (AckA) and deletions in the SCCmec element emerged in several infections. In summary, these results shed light on the multifactorial processes of infection adaptation and demonstrate how S. epidermidis is able to flexibly repurpose and edit factors important for colonization to facilitate survival in hostile infection environments.     

Genome Sequence of Candidatus Nitrososphaera evergladensis from Group I.1b Enriched from Everglades Soil Reveals Novel Genomic Features of the Ammonia-Oxidizing Archaea

The activity of ammonia-oxidizing archaea (AOA) leads to the loss of nitrogen from soil, pollution of water sources and elevated emissions of greenhouse gas. To date, eight AOA genomes are available in the public databases, seven are from the group I.1a of the Thaumarchaeota and only one is from the group I.1b, isolated from hot springs. Many soils are dominated by AOA from the group I.1b, but the genomes of soil representatives of this group have not been sequenced and functionally characterized. The lack of knowledge of metabolic pathways of soil AOA presents a critical gap in understanding their role in biogeochemical cycles. Here, we describe the first complete genome of soil archaeon Candidatus Nitrososphaera evergladensis, which has been reconstructed from metagenomic sequencing of a highly enriched culture obtained from an agricultural soil. The AOA enrichment was sequenced with the high throughput next generation sequencing platforms from Pacific Biosciences and Ion Torrent. The de novo assembly of sequences resulted in one 2.95 Mb contig. Annotation of the reconstructed genome revealed many similarities of the basic metabolism with the rest of sequenced AOA. Ca. N. evergladensis belongs to the group I.1b and shares only 40% of whole-genome homology with the closest sequenced relative Ca. N. gargensis. Detailed analysis of the genome revealed coding sequences that were completely absent from the group I.1a. These unique sequences code for proteins involved in control of DNA integrity, transporters, two-component systems and versatile CRISPR defense system. Notably, genomes from the group I.1b have more gene duplications compared to the genomes from the group I.1a. We suggest that the presence of these unique genes and gene duplications may be associated with the environmental versatility of this group.     

Anti-Inflammatory Effect of Targeted Delivery of SOD to Endothelium: Mechanism,Synergism with NO Donors and Protective Effects In Vitro and In Vivo

Pro-inflammatory activation of vascular endothelium is implicated in pathogenesis of severe conditions including stroke, infarction and sepsis. We have recently reported that superoxide dismutase (SOD) conjugated with antibodies (Ab/SOD) that provide targeted delivery into endothelial endosomes mitigates inflammatory endothelial activation by cytokines and agonists of Toll-like receptors (TLR). The goal of this study was to appraise potential utility and define the mechanism of this effect. Ab/SOD, but not non-targeted SOD injected in mice alleviated endotoxin-induced leukocyte adhesion in the cerebral vasculature and protected brain from ischemia-reperfusion injury. Transfection of endothelial cells with SOD, but not catalase inhibited NFκB signaling and expression of Vascular Cell Adhesion Molecule-1 induced by both cytokines and TLR agonists. These results affirmed that Ab/SOD-quenched superoxide anion produced by endothelial cells in response to proinflammatory agents mediates NFκB activation. Furthermore, Ab/SOD potentiates anti-inflammatory effect of NO donors in endothelial cells in vitro, as well as in the endotoxin-challenged mice. These results demonstrate the central role of intracellular superoxide as a mediator of pro-inflammatory activation of endothelium and support the notion of utility of targeted interception of this signaling pathway for management of acute vascular inflammation.     

Intragenic deletion patterns of dystrophin gene in Duchenne and Becker muscular dystrophy patients from Algeria

Duchenne and Becker muscular dystrophies (DMD and BMD) represent the most frequent neuromuscular diseases in humans (1/3,500–6,000 live male births), characterized by an X-linked recessive pattern of inheritance and therefore affecting mainly male individuals. DMD and BMD are allelic disorders resulting from genetic defects, mostly intragenic deletions, in the dystrophin gene. Using multiplex polymerase chain reaction (PCR), we have analyzed 170 male patients from unrelated families originating from Algeria, showing that 68 % of them harbored deletion events affecting the known 5′ or 3′ hot spot regions. The distal portion was predominantly involved (85 %), whereas 37 distinctive patterns of deletion were identified in our panel. The extent of deletion varied from 1 to 32 exons, although the average number was about four exons. The lack of seven exons (45, 46, 47, 48, 50, 51 and 52), each alone or in combination, represented about 78 % of the alterations encountered, while exon 48 was most frequently involved (50 %). The effect of the deletions showed that the reading frame rule proved mostly true, correlating with the clinical diagnosis suggested. Moreover, the c.525delT mutation in the γ-sarcoglycan gene was present in non-deleted patients (7 %), suggesting that clinical features can still be misleading. Finally, multiplex PCR proved to be a simple, fast and low-cost approach for the molecular diagnosis of dystrophinopathies in Algeria, whereas our data could contribute to the creation of a national registry of DMD/BMD patients in our country, which would give them hope to an access to already available genotype-based therapies.