Social Transfer of Pathogenic Fungus Promotes Active Immunisation in Ant Colonies

Social contact with fungus-exposed ants leads to pathogen transfer to healthy nest-mates, causing low-level infections. These micro-infections promote pathogen-specific immune gene expression and protective immunization of nest-mates

Iridescent aerodynamic contrails: The Norderney case of 27 June 2008

Am 27. Juni 2008 um 14:06 UTC wurde auf Norderney ein irisierender aerodynamischer Kondensstreifen eines zweistrahligen Verkehrsflugzeugs mit Kurs von Amsterdam nach Kopenhagen beobachtet und fotografiert. Um zu sehen, ob dieses Ereignis durch eine ungewöhnliche Wettersituation begünstigt wurde, untersuchen wir die meteorologische Lage. Es zeigt sich, dass aerodynamische Kondensstreifen sichtbar werden konnten, weil die Luft in Flughöhe genügend warm und feucht war. Die dynamische Situation wird ebenfalls betrachtet, und es scheint die im Flugniveau von 350 hPa vorhandene Schichtungsstabilität die Erscheinung aerodynamischer Kondensstreifen zu begünstigen. Zusätzlich untersuchen wir die umgebende hohe Bewölkung, in der sich interessante Halophänomene gezeigt hatten. Wir diskutieren die speziellen Farben des aerodynamischen Kondensstreifens von Norderney, und stellen damit fest, dass die Breite der Größenverteilung der Eiskristalle derjenige Faktor ist, der für das Irisieren ausschlaggebend ist, welche in diesem Fall aus einer Mischung von Eiskristallen mit unterschiedlichen Wachstumshistorien resultiert. Schließlich stellen wir eine Argumentation vor, dass man aerodynamische Kondensstreifen anhand der schillernden Farben von Abgaskondensstreifen unterscheiden kann, sofern sie Irisieren zeigen, was nur bei einem Winkelabstand zur Sonne von unter 30° beobachtet werden kann

Anisotropic composite material phantom to improve skeletal muscle characterization using magnetic resonance elastography

The presence and progression of neuromuscular pathology, including spasticity, Duchenne's muscular dystrophy and hyperthyroidism, has been correlated with changes in the intrinsic mechanical properties of skeletal muscle tissue. Tools for noninvasively measuring and monitoring these properties, such as Magnetic Resonance Elastography (MRE), could benefit basic research into understanding neuromuscular pathologies, as well as translational research to develop therapies, by providing a means of assessing and tracking their efficacy. Dynamic elastography methods for noninvasive measurement of tissue mechanical properties have been under development for nearly three decades. Much of the technological development to date, for both Ultrasound (US)-based and Magnetic Resonance Imaging (MRI)-based strategies, has been grounded in assumptions of local homogeneity and isotropy. Striated skeletal and cardiac muscle, as well as brain white matter and soft tissue in some other organ regions, exhibit a fibrous microstructure which entails heterogeneity and anisotropic response; as one seeks to improve the accuracy and resolution in mechanical property assessment, heterogeneity and anisotropy need to be accounted for in order to optimize both the dynamic elastography experimental protocol and the interpretation of the measurements. Advances in elastography methodology at every step have been aided by the use of tissue-mimicking phantoms. The aim of the present study was to develop and characterize a heterogeneous composite phantom design with uniform controllable anisotropic properties meant to be comparable to the frequency-dependent anisotropic properties of skeletal muscle. MRE experiments and computational finite element (FE) studies were conducted on a novel 3D-printed composite phantom design. The displacement maps obtained from simulation and experiment show the same elliptical shaped wavefronts elongated in the plane where the structure presents higher shear modulus. The model exhibits a degree of anisotropy in line with literature data from skeletal muscle tissue MRE experiments. FE simulations of the MRE experiments provide insight into proper interpretation of experimental measurements, and help to quantify the importance of heterogeneity in the anisotropic material at different scales

Data from: Social transfer of pathogenic fungus promotes active immunisation in ant colonies

Due to the omnipresent risk of epidemics, insect societies have evolved sophisticated disease defences at the individual and colony level. An intriguing yet little understood phenomenon is that social contact to pathogen-exposed individuals reduces susceptibility of previously naive nestmates to this pathogen. We tested whether such social immunisation in Lasius ants against the entomopathogenic fungus Metarhizium anisopliae is based on active upregulation of the immune system of nestmates following contact to an infectious individual or passive protection via transfer of immune effectors among group members—that is, active versus passive immunisation. We found no evidence for involvement of passive immunisation via transfer of antimicrobials among colony members. Instead, intensive allogrooming behaviour between naive and pathogen-exposed ants before fungal conidia firmly attached to their cuticle suggested passage of the pathogen from the exposed individuals to their nestmates. By tracing fluorescence-labelled conidia we indeed detected frequent pathogen transfer to the nestmates, where they caused low-level infections as revealed by growth of small numbers of fungal colony forming units from their dissected body content. These infections rarely led to death, but instead promoted an enhanced ability to inhibit fungal growth and an active upregulation of immune genes involved in antifungal defences (defensin and prophenoloxidase, PPO). Contrarily, there was no upregulation of the gene cathepsin L, which is associated with antibacterial and antiviral defences, and we found no increased antibacterial activity of nestmates of fungus-exposed ants. This indicates that social immunisation after fungal exposure is specific, similar to recent findings for individual-level immune priming in invertebrates. Epidemiological modeling further suggests that active social immunisation is adaptive, as it leads to faster elimination of the disease and lower death rates than passive immunisation. Interestingly, humans have also utilised the protective effect of low-level infections to fight smallpox by intentional transfer of low pathogen doses (“variolation” or “inoculation”)

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Monandria to Syngenesia

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Monandria to Syngenesia

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