Looking beyond endotoxin: a comparative study of pyrogen retention by ultrafilters used for the preparation of sterile dialyis fluid

Sterile single-use ultrafilters are used in dialysis for the preparation of the substitution fluid given to patients undergoing dialysis treatments with high convective fluid removal. The retention of pyrogenic agents by the ultrafilters is crucial to avoiding inflammatory responses. The performance of a new single-use ultrafilter (NUF) with a positively charged flat sheet membrane of relatively small membrane area and large pore size was compared to a reference ultrafilter (RUF) with a hollow fiber membrane. Filter performance was tested with various pyrogen-contaminated dialysis fluids by direct pyrogen quantification and by measuring inflammatory responses in cell-based bioassays. The NUF completely retained oligodeoxynucleotides (ODN), whereas the RUF was fully permeable. Both filters tended to decrease biological activity of DNA in filtered bacterial lysates. The NUF reduced lipopolysaccharides (LPS) and LPS-induced biological activity by 100%, whereas the RUF produced filtrates with low but detectable levels of LPS in most cases. Peptidoglycans (PGN) were fully retained both by the NUF and the RUF. The new ultrafilter retained biologically active ODN, which has not yet been described for any other device used in dialysis, and it showed better or equal retention of LPS and PGN even with a smaller membrane surface and larger pore size

Ectomycorrhizal Community Shifts at a Former Uranium Mining Site

Ectomycorrhizal communities at young oak, pine, and birch stands in a former uranium mining site showed a low diversity of morphotypes with a preference for contact and short-distance exploration strategies formed by the fungi Russulaceae , Inocybaceae , Cortinariaceae , Thelephoraceae , Rhizopogonaceae , Tricholomataceae , as well as abundant Meliniomyces bicolor . In order to have better control over abiotic conditions, we established pot experiments with re-potted trees taken from the sites of direct investigation. This more standardized cultivation resulted in a lower diversity and decreased prominence of M. bicolor . In addition, the exploration strategies shifted to include long-distance exploration types. To mimic secondary succession with a high prevalence of fungal propagules present in the soil, inoculation of re-potted trees observed under standardized conditions for two years was used. The super-inoculation increased the effect of lower abundance and diversity of morphotypes. The contact morphotypes correlated with high Al, Cu, Fe, Sr, and U soil contents, the dark-colored short-distance exploration type did not show a specific preference for soil characteristics, and the medium fringe type with rhizomorphs on oaks correlated with total nitrogen. Thus, we could demonstrate that field trees, in a species-dependent manner, selected for ectomycorrhizal fungi with exploration types are likely to improve the plant’s tolerance to specific abiotic conditions

The parasitic-neutral-mutual continuum of plant-fungal interactions

Interactions of plants with fungi are of imminent importance to crop production and thus for human nutrition. However, interactions range from pathogenic fungi, e.g. cereal rusts, to beneficial interactions with plant growth promotion through soil, endophytic or mycorrhizal fungi. Thus, mutually beneficial, neutral or parasitic/pathogenic interactions can be distinguished. In order to identify more general mechanisms on the fungal side coping with environmental and plant response associated stress, modern technologies are available including the -omics technologies. In addition to that, the comparison of the different interactions may be compared, both on a more general level, but also at very small scale to identify the different parameters guiding interchange of nutrients and signals. This will allow for a holistic view on plant health necessary to establish eco-friendly technologies also in crop protection and plant nutrition

The functional significance of alternative photorespiratory pathways in Arabidopsis thaliana

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What role might non-mating receptors play in Schizophyllum commune?

The B mating-type locus of the tetrapolar basidiomycete Schizophyllum commune encodes pheromones and pheromone receptors in multiple allelic specificities. This work adds substantial new evidence into the organization of the B mating-type loci of distantly related S. commune strains showing a high level of synteny in gene order and neighboring genes. Four pheromone receptor-like genes were found in the genome of S. commune with brl1, brl2 and brl3 located at the B mating-type locus, whereas brl4 is located separately. Expression analysis of brl genes in different developmental stages indicates a function in filamentous growth and mating. Based on the extensive sequence analysis and functional characterization of brl-overexpression mutants, a function of Brl1 in mating is proposed, while Brl3, Brl4 and Brl2 (to a lower extent) have a role in vegetative growth, possible determination of growth direction. The brl3 and brl4 overexpression mutants had a dikaryonlike, irregular and feathery phenotype, and they avoided the formation of same-clone colonies on solid medium, which points towards enhanced detection of self-signals. These data are supported by localization of Brl fusion proteins in tips, at septa and in not-yet-fused clamps of a dikaryon, confirming their importance for growth and development in S. commune

Geosmin synthase ges1 knock‐down by siRNA in the dikaryotic fungus Tricholoma vaccinum

Abstract Genetic manipulation for generating knock‐out experiments is essential in deciphering the precise function of a gene. However, dikaryotic fungi pose the inherent challenge of having two allelic versions of each gene, one in each nucleus. In addition, they often are slow‐growing and do not withstand protoplasting, which is why Agrobacterium tumefaciens ‐mediated transformation has been adapted. To obtain knock‐out strains, however, is not feasible with a mere deletion construct transformation and screening for deletions in both nuclear copies. Hence, a convenient method using chemically synthesized dicer substrate interfering RNA (DsiRNA) for posttranscriptional interference of targeted mRNA was developed, based on the fungal dicer/argonaute system inherent in fungi for sequence recognition and degradation. A proof‐of‐principle using this newly established method for knock‐down of the volatile geosmin is presented in the dikaryotic fungus Tricholoma vaccinum that is forming ectomycorrhizal symbiosis with spruce trees. The gene ges1 , a terpene synthase, was transcribed with a 50‐fold reduction in transcript levels in the knockdown strain. The volatile geosmin was slightly reduced, but not absent in the fungus carrying the knockdown construct pointing at low specificity in other terpene synthases known for that class of enzymes

Impacts of a reduction of seawater pH mimicking ocean acidification impacts on assemblage, structure and diversity of marine fungal communities

Increases in atmospheric carbon dioxide (CO2) change ocean chemistry, as dissolved CO2 leads to a reduction in the seawater pH. Many marine taxa have been shown to be affected by ocean acidification, while information on marine fungi is lacking. Here, we analyze the effect of pH on mycoplankton communities. The pH of microcosms was adjusted to a value mimicking the predicted ocean acidification in the near future. Fungal communities were analyzed using a double-marker gene approach, allowing a more detailed analysis of their response using 454 pyrosequencing. Mycoplankton communities in microcosms with in situ and adjusted water pH values differed significantly in terms of structure and diversity. The differences were mainly based on abundance shifts among the dominant taxa rather than the exclusion of fungal groups. A sensitivity to lower pH values was reported for several groups across the fungal kingdom and was not phylogenetically conserved. Some of the fungal species that dominated the communities of microcosms with a lower pH were known pathogenic fungi. With the increasing awareness of the significant role fungi play in marine systems, including performing a diverse range of symbiotic activities, our results highlight the importance of including fungi in further research projects studying and modeling biotic responses to the predicted ocean acidification

Heterotic Cosmic Strings

We show that all three conditions for the cosmological relevance of heterotic cosmic strings, the right tension, stability and a production mechanism at the end of inflation, can be met in the strongly coupled M-theory regime. Whereas cosmic strings generated from weakly coupled heterotic strings have the well known problems posed by Witten in 1985, we show that strings arising from M5-branes wrapped around 4-cycles (divisors) of a Calabi-Yau in heterotic M-theory compactifications, solve these problems in an elegant fashion.Comment: 25 pages, v2: section and references adde

Organic acids, siderophores, enzymes and mechanical pressure for black slate bioweathering with the basidiomycete Schizophyllum commune

Although many fungi are known to be able to perform bioweathering of rocks and minerals, little information is available concerning the role of basidiomycetes in this process. The wood-rotting basidiomycete Schizophyllum commune was investigated for its ability to degrade black slate, a rock rich in organic carbon. Mechanical pressure of hyphae and extracellular polymeric substances was investigated for biophysical weathering. A mixed ß1-3/ß1-6 glucan, likely schizophyllan that is well known from S. commune, could be identified on black slate surfaces. Secretion of siderophores and organic acids as biochemical weathering agents was shown. Both may contribute to biochemical weathering in addition to enzymatic functions. Previously, the exoenzyme laccase was believed to attack organic the matter within the black slate, thereby releasing metals from the rock. Here, overexpression of laccase showed enhanced dissolution of quartz phases by etching and pitting. At the same time, the formation of a new secondary mineral phase, whewellite, could be demonstrated. Hence, a more comprehensive understanding of biophysical as well as biochemical weathering by S. commune could be reached and unexpected mechanisms like quartz dissolution linked to shale degradation. © 2019 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd

M-Theory Inflation from Multi M5-Brane Dynamics

We derive inflation from M-theory on S^1/Z_2 via the non-perturbative dynamics of N M5-branes. The open membrane instanton interactions between the M5-branes give rise to exponential potentials which are too steep for inflation individually but lead to inflation when combined together. The resulting type of inflation, known as assisted inflation, facilitates considerably the requirement of having all moduli, except the inflaton, stabilized at the beginning of inflation. During inflation the distances between the M5-branes, which correspond to the inflatons, grow until they reach the size of the S^1/Z_2 orbifold. At this stage the M5-branes will reheat the universe by dissolving into the boundaries through small instanton transitions. Further flux and non-perturbative contributions become important at this late stage, bringing inflation to an end and stabilizing the moduli. We find that with moderate values for N, one obtains both a sufficient amount of e-foldings and the right size for the spectral index.Comment: 30 pages, 3 figures; v3: one comment and refs adde