During the past 15 years the saprophytic fungus
Aspergillus fumigatus has become the most prevalent airborne fungal pathogen, causing severe and often fatal infections especially in ...immuno-compromised patients. Germination of inhaled conidia is an early and crucial event in the infection process of
A. fumigatus. In this study we have analyzed morphological changes that take place during this differentiation process using scanning electron microscopy. Our data show that (i) the hydrophobic surface layer of resting conidia seems to be shed before the cells start to swell and (ii) that filamentous surface appendages are expressed at a very early phase of the germtube formation. These surface structures were only found on the first few μm of the germtube, but were absent from the surface of mycelial hyphae and resting or swollen conidia. The highly regulated expression of these novel surface organelles suggests that they may play an important role during early germination and represent a potential target for future anti-
A. fumigatus therapies.
Government officials can have a disposition to conceptualise the behaviour of policy target groups as stable, malleable, or something in-between. This paper hypothesizes these conceptualisations to ...influence preferences for policy instruments: Officials seeing behaviour to be more stable are hypothesised to prefer enforcement when aiming to change behaviour, whereas officials assuming behaviour to be more malleable are hypothesised to prefer information provision and behavioural instruments. Using a survey among local government officials from the Netherlands (N = 717), we tested these hypotheses in the context of compliance with rules to prevent the spread of Covid-19. Results show that officials assuming behaviour to be more stable preferred more enforcement and information provision to change behaviour than officials assuming behaviour to be more malleable. This may suggest that seeing behaviour as more stable leads officials to prefer more government intervention in general. Conceptualisations about the changeableness of behaviour were not related to preferences for behavioural instruments. Implications for government officials are discussed.
The localization of carbon monoxide oxidase (CO oxidase), the key enzyme in CO metabolism of Pseudomonas carboxydovorans, was examined using modified immunoferritin and protein A-gold techniques. ...Cell extracts were incubated with specific immunoglobulin G antibodies raised against CO oxidase, followed by treatment with ferritin-conjugated goat-anti-rabbit immunoglobulin G antibodies (pre-embedding labeling). Electron microscopic examination of ultrathin sections showed cytoplasmic membranes and inside-out vesicles labeled at the inner aspect, whereas the outer sides of protoplasts and membrane vesicles remained completely unlabeled. The highly sensitive protein A-gold method has been modified to allow labeling of CO oxidase with good ultrastructural preservation of the bacterial cell. Glutaraldehyde-fixed cells of P. carboxydovorans were osmificated and embedded in glycol methacrylate. Etched ultrathin sections were treated with sodium metaperiodate and incubated with the specific antibodies against CO oxidase. These antibodies were then allowed to react with protein A-gold complexes (postembedding labeling). Exponentially grown cells showed 87% of CO oxidase associated with the cytoplasmic membrane and 13% of the enzyme in the cytoplasm. The results indicate that CO oxidase is attached in vivo to the inner aspect of the cytoplasmic membrane and suggest interaction of the enzyme with a membrane-bound electron acceptor. The ratio of enzyme associated with the cytoplasmic membrane decreased to 50% in the stationary growth phase.
We recently described the phase-variable expression of a virulence-associated lipopolysaccharide (LPS) epitope in Legionella pneumophila. In this study, the molecular mechanism for phase variation ...was investigated. We identified a 30 kb unstable genetic element as the molecular origin for LPS phase variation. Thirty putative genes were encoded on the 30 kb sequence, organized in two putative opposite transcription units. Some of the open reading frames (ORFs) shared homologies with bacteriophage genes, suggesting that the 30 kb element was of phage origin. In the virulent wild-type strain, the 30 kb element was located on the chromosome, whereas excision from the chromosome and replication as a high-copy plasmid resulted in the mutant phenotype, which is characterized by alteration of an LPS epitope and loss of virulence. Mapping and sequencing of the insertion site in the genome revealed that the chromosomal attachment site was located in an intergenic region flanked by genes of unknown function. As phage release could not be induced by mitomycin C, it is conceivable that the 30 kb element is a non-functional phage remnant. The protein encoded by ORF T on the 30 kb plasmid could be isolated by an outer membrane preparation, indicating that the genes encoded on the 30 kb element are expressed in the mutant phenotype. Therefore, it is conceivable that the phenotypic alterations seen in the mutant depend on high-copy replication of the 30 kb element and expression of the encoded genes. Excision of the 30 kb element from the chromosome was found to occur in a RecA-independent pathway, presumably by the involvement of RecE, RecT and RusA homologues that are encoded on the 30 kb element.
Modeling and simulation tools have become an integral part of modern engineering processes. In particular, accurate and efficient simulation tools are critical for the design, development, and ...testing of autonomous unmanned ground vehicles (UGVs). However, because of the complexity of the problem, many UGV simulators are computationally intensive, require expensive hardware to run, and are often not interactive or real-time. Those simulation environments that do provide users with some degree of interactivity and real-time or faster performance gain these features at the sacrifice of simulation fidelity, and these products often provide inadequate results. A new simulation environment for UGV design and development, called the Autonomous Navigation Virtual Environment Laboratory (ANVEL), has been created to address the need for a real-time, interactive, physics-based simulation environment for UGVs. ANVEL is able to meet this need by fusing readily available, off-the-shelf video game technology with high-fidelity, physics-based models. This paper presents the methodology used in developing ANVEL, an example use of ANVEL for development and testing of an autonomous UGV, and plans for the future development.
We have developed a novel approach to characterize protein digests by pneumatic-splitter electrospray ionization liquid chromatography mass spectrometry (PSESI-LCMS). This technique involves an ...interfacing of a pneumatic splitter that can dynamically generate and control a steady split flow rate of nanoliters per minute. An average PSESI-LCMS analysis, depending on the desired split ratio, consumes less than 200 femtomoles of sample. A tryptic digest map of a glycoprotein, fetuin, and a Lys-C digest map of a recombinant neurotrophin protein, neurotrophin-3, are reported here for this investigation.
Strain XLG9A10.2T was isolated from an alkaline salt marsh soil in western China. 16S rRNA gene sequence analysis indicated that strain XLG9A10.2T constitutes a distinct lineage within the family ...Promicromonosporaceae, sharing 94.8-95.1% gene similarity with members of the genus Promicromonospora and 94.4-95.7% similarity with those of Xylanimonas and related genera. The general colony and cell morphology of strain XLG9A10.2T is similar to that of members of Promicromonospora, but differs from members of the genus Xylanimonas in forming a well-developed branching mycelium and production of coccoid spores. Strain XLG9A10.2T shows the peptidoglycan type A4alpha (L-lys<--L-thr<--D-Glu), contains glucose, mannose and galactose as whole cell sugars and has MK-9(H4) and MK-9(H6) as major menaquinones, while phospholipids are phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, three unidentified phospholipids and one unidentified glycolipid. The DNA base composition is 71.9 mol% G+C. On the basis of morphological, chemotaxonomic, metabolic and phylogenetic differences from other species of Promicromonosporaceae, a new genus and species, Myceligenerans xiligouense gen. nov., sp. nov., is proposed. The type strain is XLG9A10.2T (=DSM 15700T=CGMCC 1.3458T.)
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