The most heat-resistant conidia observed to date are formed by distinct strains of Paecilomyces variotii

Fungi colonize habitats by means of spores. These cells are stress-resistant compared with growing fungal cells. Fungal conidia, asexual spores, formed by cosmopolitan fungal genera like Penicillium, Aspergillus and Peacilomyces are dispersed by air. They are present in places where food products are stored and as a result, they cause food spoilage. Here, we determined the heterogeneity of heat resistance of conidia between and within strains of Paecilomyces variotii, a spoiler of foods such as margarine, fruit juices, canned fruits and non-carbonized sodas. Out of 108 strains, 31 isolates showed a conidial survival >10% after a 10-min-heat treatment at 59°C. Three strains with different conidial heat resistance were selected for further phenotyping. Conidia of DTO 212-C5 and DTO 032-I3 showed 0.3% and 2.6% survival in the screening respectively, while survival of DTO 217-A2 conidia was >10%. The decimal reduction times of these strains at 60°C (D₆₀ value) were 3.7 ± 0.08, 5.5 ± 0.35 and 22.9 ± 2.00 min respectively. Further in-depth analysis revealed that the three strains showed differences in morphology, spore size distributions, compatible solute compositions and growth under salt stress. Conidia of DTO 217-A2 are the most heat-resistant reported so far. The ecological consequences of this heterogeneity of resistance, including food spoilage, are discussed.     

Temporal Quantitative Proteomics of mGluR-induced Protein Translation and Phosphorylation in Neurons

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Highlights

• •Integrated phosphoproteomics and analyses of newly synthesized proteins in neurons.
• •Resource of temporal mGluR-induced signaling pathways upon DHPG stimulation.
• •Validation of PKC, MAPK1, CAMKIIa, and CDK2 in mGluR-activation and signaling.
• •Validation of Intersectin-1 in DHPG-induced AMPAR internalization.

     

Colorful Protein-Based Fluorescent Probes for Collagen Imaging

Real-time visualization of collagen is important in studies on tissue formation and remodeling in the research fields of developmental biology and tissue engineering. Our group has previously reported on a fluorescent probe for the specific imaging of collagen in live tissue in situ, consisting of the native collagen binding protein CNA35 labeled with fluorescent dye Oregon Green 488 (CNA35-OG488). The CNA35-OG488 probe has become widely used for collagen imaging. To allow for the use of CNA35-based probes in a broader range of applications, we here present a toolbox of six genetically-encoded collagen probes which are fusions of CNA35 to fluorescent proteins that span the visible spectrum: mTurquoise2, EGFP, mAmetrine, LSSmOrange, tdTomato and mCherry. While CNA35-OG488 requires a chemical conjugation step for labeling with the fluorescent dye, these protein-based probes can be easily produced in high yields by expression in E. coli and purified in one step using Ni²⁺-affinity chromatography. The probes all bind specifically to collagen, both in vitro and in porcine pericardial tissue. Some first applications of the probes are shown in multicolor imaging of engineered tissue and two-photon imaging of collagen in human skin. The fully-genetic encoding of the new probes makes them easily accessible to all scientists interested in collagen formation and remodeling.     

Optimizing the Distribution of Leg Muscles for Vertical Jumping

A goal of biomechanics and motor control is to understand the design of the human musculoskeletal system. Here we investigated human functional morphology by making predictions about the muscle volume distribution that is optimal for a specific motor task. We examined a well-studied and relatively simple human movement, vertical jumping. We investigated how high a human could jump if muscle volume were optimized for jumping, and determined how the optimal parameters improve performance. We used a four-link inverted pendulum model of human vertical jumping actuated by Hill-type muscles, that well-approximates skilled human performance. We optimized muscle volume by allowing the cross-sectional area and muscle fiber optimum length to be changed for each muscle, while maintaining constant total muscle volume. We observed, perhaps surprisingly, that the reference model, based on human anthropometric data, is relatively good for vertical jumping; it achieves 90% of the jump height predicted by a model with muscles designed specifically for jumping. Alteration of cross-sectional areas—which determine the maximum force deliverable by the muscles—constitutes the majority of improvement to jump height. The optimal distribution results in large vastus, gastrocnemius and hamstrings muscles that deliver more work, while producing a kinematic pattern essentially identical to the reference model. Work output is increased by removing muscle from rectus femoris, which cannot do work on the skeleton given its moment arm at the hip and the joint excursions during push-off. The gluteus composes a disproportionate amount of muscle volume and jump height is improved by moving it to other muscles. This approach represents a way to test hypotheses about optimal human functional morphology. Future studies may extend this approach to address other morphological questions in ethological tasks such as locomotion, and feature other sets of parameters such as properties of the skeletal segments.     

Atomically Defined Templates for Epitaxial Growth of Complex Oxide Thin Films

Atomically defined substrate surfaces are prerequisite for the epitaxial growth of complex oxide thin films. In this protocol, two approaches to obtain such surfaces are described. The first approach is the preparation of single terminated perovskite SrTiO₃ (001) and DyScO₃ (110) substrates. Wet etching was used to selectively remove one of the two possible surface terminations, while an annealing step was used to increase the smoothness of the surface. The resulting single terminated surfaces allow for the heteroepitaxial growth of perovskite oxide thin films with high crystalline quality and well-defined interfaces between substrate and film. In the second approach, seed layers for epitaxial film growth on arbitrary substrates were created by Langmuir-Blodgett (LB) deposition of nanosheets. As model system Ca₂Nb₃O₁₀^- nanosheets were used, prepared by delamination of their layered parent compound HCa₂Nb₃O₁₀. A key advantage of creating seed layers with nanosheets is that relatively expensive and size-limited single crystalline substrates can be replaced by virtually any substrate material.     

Pathogenic ubiquitination of GSDMB inhibits NK cell bactericidal functions

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Catastrophic Collapse Can Occur without Early Warning: Examples of Silent Catastrophes in Structured Ecological Models

Catastrophic and sudden collapses of ecosystems are sometimes preceded by early warning signals that potentially could be used to predict and prevent a forthcoming catastrophe. Universality of these early warning signals has been proposed, but no formal proof has been provided. Here, we show that in relatively simple ecological models the most commonly used early warning signals for a catastrophic collapse can be silent. We underpin the mathematical reason for this phenomenon, which involves the direction of the eigenvectors of the system. Our results demonstrate that claims on the universality of early warning signals are not correct, and that catastrophic collapses can occur without prior warning. In order to correctly predict a collapse and determine whether early warning signals precede the collapse, detailed knowledge of the mathematical structure of the approaching bifurcation is necessary. Unfortunately, such knowledge is often only obtained after the collapse has already occurred.     

Influence of nutrients, submerged macrophytes and zooplankton grazing on phytoplankton biomass and diversity along a latitudinal gradient in Europe

In order to evaluate latitudinal differences in the relationship of phytoplankton biomass and diversity with environmental conditions in shallow lakes, we sampled 98 shallow lakes from three European regions: Denmark (DK), Belgium/The Netherlands (BNL) and southern Spain (SP). Phytoplankton biomass increased with total phosphorus (TP) concentrations and decreased with submerged macrophyte cover across the three regions. Generic richness was significantly negatively related to submerged macrophyte cover and related environmental variables. Zooplankton:phytoplankton biomass ratios were positively related to submerged macrophyte cover and negatively to phytoplankton generic richness in DK and BNL, suggesting that the low generic richness in lakes with submerged macrophytes was due to a higher zooplankton grazing pressure in these regions. In SP, phytoplankton generic richness was not influenced by zooplankton grazing pressure but related to conductivity. We observed no relationship between phytoplankton generic richness and TP concentration in any of the three regions. The three regions differed significantly with respect to mean local and regional generic richness, with BNL being more diverse than the other two regions. Our observations suggest that phytoplankton diversity in European shallow lakes is influenced by submerged macrophyte cover indirectly by modulating zooplankton grazing. This influence of submerged macrophytes and zooplankton grazing on phytoplankton diversity decreases from north to south.