Cataglyphis ant navigation strategies solve the global localization problem in robots with binary sensors

Low cost robots, such as vacuum cleaners or lawn mowers, employ simplistic and often random navigation policies. Although a large number of sophisticated localization and planning approaches exist, they require additional sensors like LIDAR sensors, cameras or time of flight sensors. In this work, we propose a global localization method biologically inspired by simple insects, such as the ant Cataglyphis that is able to return from distant locations to its nest in the desert without any or with limited perceptual cues. Like in Cataglyphis, the underlying idea of our localization approach is to first compute a pose estimate from pro-prioceptual sensors only, using land navigation, and thereafter refine the estimate through a systematic search in a particle filter that integrates the rare visual feedback. In simulation experiments in multiple environments, we demonstrated that this bioinspired principle can be used to compute accurate pose estimates from binary visual cues only. Such intelligent localization strategies can improve the performance of any robot with limited sensing capabilities such as household robots or toys.Comment: Accepted to BIOSIGNALS 201

Comparative metagenomics of biogas-producing microbial communities from production-scale biogas plants operating under wet or dry fermentation conditions

Stolze Y, Zakrzewski M, Maus I, et al. Comparative metagenomics of biogas-producing microbial communities from production-scale biogas plants operating under wet or dry fermentation conditions. Biotechnology for Biofuels. 2015;8(1): 14.Background Decomposition of biomass for biogas production can be practiced under wet and dry fermentation conditions. In contrast to the dry fermentation technology, wet fermentation is characterized by a high liquid content and a relatively low total solid content. In this study, the composition and functional potential of a biogas-producing microbial community in an agricultural biogas reactor operating under wet fermentation conditions was analyzed by a metagenomic approach applying 454-pyrosequencing. The obtained metagenomic dataset and corresponding 16S rRNA gene amplicon sequences were compared to the previously sequenced comparable metagenome from a dry fermentation process, meeting explicitly identical boundary conditions regarding sample and community DNA preparation, sequencing technology, processing of sequence reads and data analyses by bioinformatics tools. Results High-throughput metagenome sequencing of community DNA from the wet fermentation process applying the pyrosequencing approach resulted in 1,532,780 reads, with an average read length of 397 bp, accounting for approximately 594 million bases of sequence information in total. Taxonomic comparison of the communities from wet and dry fermentation revealed similar microbial profiles with Bacteria being the predominant superkingdom, while the superkingdom Archaea was less abundant. In both biogas plants, the bacterial phyla Firmicutes, Bacteroidetes, Spirochaetes and Proteobacteria were identified with descending frequencies. Within the archaeal superkingdom, the phylum Euryarchaeota was most abundant with the dominant class Methanomicrobia. Functional profiles of the communities revealed that environmental gene tags representing methanogenesis enzymes were present in both biogas plants in comparable frequencies. 16S rRNA gene amplicon high-throughput sequencing disclosed differences in the sub-communities comprising methanogenic Archaea between both processes. Fragment recruitments of metagenomic reads to the reference genome of the archaeon Methanoculleus bourgensis MS2T revealed that dominant methanogens within the dry fermentation process were highly related to the reference. Conclusions Although process parameters, substrates and technology differ between the wet and dry biogas fermentations analyzed in this study, community profiles are very similar at least at higher taxonomic ranks, illustrating that core community taxa perform key functions in biomass decomposition and methane synthesis. Regarding methanogenesis, Archaea highly related to the type strain M. bourgensis MS2T dominate the dry fermentation process, suggesting the adaptation of members belonging to this species to specific fermentation process parameters

Mikrobielle Nutzung von Ernteresten in Bodensäulen und Litterbags

Die vorliegende Arbeit wurde im Rahmen des Graduiertenkollegs 1397 "Regulation of soil organic matter and nutrient turnover in organic agriculture" von der Deutschen Forschungsgemeinschaft (DFG) finanziert

Pharmacokinetics of Saquinavir, Atazanavir, and Ritonavir in a Twice-Daily Boosted Double-Protease Inhibitor Regimen

The objective of this study was to evaluate the pharmacokinetics of atazanavir (ATV), saquinavir (SQV), and ritonavir (RTV) in a boosted double-protease inhibitor (PI) therapy regimen without reverse transcriptase inhibitors (RTIs). The study design was as follows. Patients with limited RTI options received a PI combination of 300/100 mg ATV/RTV once daily and 1,000 mg SQV twice daily (group 1; n = 49) without RTI comedication. The results were compared to the plasma concentrations of PIs of patients taking either 300 mg ATV/100 mg RTV once daily plus RTIs (group 2; n = 72) or patients taking 1,000 mg SQV/100 mg RTV plus RTIs (group 3; n = 90). The study methods were as follows. Patients were given a 12/24-h pharmacokinetic assessment at steady state. Drug concentrations were measured by liquid chromatography-tandem mass spectrometry. The minimum and maximum concentrations (C(min) and C(max)), area under the concentration-time curve under steady-state conditions (AUC(ss)), elimination half-life, time of maximum concentration and lag time were subject to statistical analysis. The results show that patients treated with ATV/SQV/RTV exhibited significantly high SQV concentrations and moderate enhancement of the AUC(ss) of ATV in comparison to those of patients of the control groups: for SQV in groups 1 and 3, the geometric mean (GM) of the AUC(ss) was 22,794 versus 15,759 ng·h/ml (GM ratio [GMR] = 1.45; P < 0.05), the GM of the C(max) was 3,257 versus 2,331 ng/ml (GMR = 1.40; P < 0.05), and the GM of the C(min) was 438 versus 437 ng/ml (GMR = 1.00); for ATV in groups 1 and 2, the GM of the AUC(ss) was 39,154 versus 33,626 ng·h/ml (GMR = 1.16), the GM of the C(max) was 3,488 versus 2,924 ng/ml (GMR = 1.20), and the GM of the C(min) was 515 versus 428 ng/ml (GMR = 1.21). RTV levels were comparable for all groups. A subgroup analysis detected only marginal differences in ATV plasma exposure if combined with tenofovir-disoproxilfumarate and without it. We conclude that our pharmacokinetic results support the use of a boosted double-PI regimen of ATV/SQV/RTV as a treatment option for patients who need antiretroviral therapy without RTIs

Potent inhibitors of plasmodial serine hydroxymethyltransferase (SHMT) featuring a spirocyclic scaffold

With the discovery that serine hydroxymethyltransferase (SHMT) is a druggable target for antimalarials, the aim of this study was to design novel inhibitors of this key enzyme in the folate biosynthesis cycle. Herein, 19 novel spirocyclic ligands based on either 2-indolinone or dihydroindene scaffolds and featuring a pyrazolopyran core are reported. Strong target affinities for Plasmodium falciparum (Pf) SHMT (14-76 nm) and cellular potencies in the low nanomolar range (165-334 nm) were measured together with interesting selectivity against human cytosolic SHMT1 (hSHMT1). Four co-crystal structures with Plasmodium vivax (Pv) SHMT solved at 2.2-2.4 Å resolution revealed the key role of the vinylogous cyanamide for anchoring ligands within the active site. The spirocyclic motif in the molecules enforces the pyrazolopyran core to adopt a substantially more curved conformation than that of previous non-spirocyclic analogues. Finally, solvation of the spirocyclic lactam ring of the receptor-bound ligands is discussed

Gift from nature : cyclomarin s kills Mycobacteria and malaria parasites by distinct modes of action

Malaria continues to be one of the most devastating human diseases despite many efforts to limit its spread by prevention of infection or by pharmaceutical treatment of patients. We have conducted a screen for antiplasmodial compounds by using a natural product library. Here we report on cyclomarin A as a potent growth inhibitor of Plasmodium falciparum and the identification of its molecular target, diadenosine triphosphate hydrolase (PfAp3Aase), by chemical proteomics. Using a biochemical assay, we could show that cyclomarin A is a specific inhibitor of the plasmodial enzyme but not of the closest human homologue hFHIT. Co-crystallisation experiments demonstrate a unique binding mode of the inhibitor. One molecule of cyclomarin A binds a dimeric PfAp3Aase and prevents the formation of the enzyme⋅substrate complex. These results validate PfAp3Aase as a new drug target for the treatment of malaria. We have previously elucidated the structurally unrelated regulatory subunit ClpC1 of the ClpP protease as the molecular target of cyclomarin A in Mycobacterium tuberculosis. Thus, cyclomarin A is a rare example of a natural product with two distinct and specific modes of action