Efficient band-selective homonuclear CO–CA cross-polarization in protonated proteins

Previously introduced for highly deuterated proteins, band-selective magnetization transfer between CO and CA spins by dipolar-based homonuclear cross polarization is applied here to a protonated protein. Robust and efficient recoupling is achieved when the sum of effective radio-frequency fields on CO and CA resonances equals two times the spinning rate, yielding up to 33 % of magnetization transfer efficiency in protonated ubiquitin. The approach is designed for moderate magic-angle spinning rates and high external magnetic fields when the isotropic chemical shift difference of CO and CA considerably exceeds the spinning rate. This method has been implemented in N_iCO_i?1CA_i?1 and CA_i(N_i)CO_i?1CA_i?1 two-dimensional interresidual correlation experiments for fast and efficient resonance assignment of ubiquitin by solid-state NMR spectroscopy.     

Die feinstruktur der flüigelschuppen einiger Lycaeniden (Insecta,Lepidoptera)

Green, blue and violet colours of Lycaenidae examined by us — with the exception of Rapala arata (Theclinae) — are due to iridescent scales which are arranged before a dark background. The iridescent scales are constructed according to the Urania-type and may be diverted from pigmented scales by laying in equidistant lamellae and little cuticular bars, which maintain the distance between the lamellae. The ribs in the longitudinal axis of the scales contain lamellae and bars only in the Plebejinae, in Lycaeninae and Theclinae they are small and sit on the plain upperside of the scale with a narrow base.

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Mit Unterstützung durch die Deutsche Forschungsgemeinschaft     

Cutting out the middle clam: lucinid endosymbiotic bacteria are also associated with seagrass roots worldwide

Seagrasses and lucinid bivalves inhabit highly reduced sediments with elevated sulphide concentrations. Lucinids house symbiotic bacteria (Ca. Thiodiazotropha) capable of oxidising sediment sulphide, and their presence in sediments has been proposed to promote seagrass growth by decreasing otherwise phytotoxic sulphide levels. However, vast and productive seagrass meadows are present in ecosystems where lucinids do not occur. Hence, we hypothesised that seagrasses themselves host these sulphur-oxidising Ca. Thiodiazotropha that could aid their survival when lucinids are absent. We analysed newly generated and publicly available 16S rRNA gene sequences from seagrass roots and sediments across 14 seagrass species and 10 countries and found that persistent and colonising seagrasses across the world harbour sulphur-oxidising Ca. Thiodiazotropha, regardless of the presence of lucinids. We used fluorescence in situ hybridisation to visually confirm the presence of Ca. Thiodiazotropha on roots of Halophila ovalis, a colonising seagrass species with wide geographical, water depth range, and sedimentary sulphide concentrations. We provide the first evidence that Ca. Thiodiazotropha are commonly present on seagrass roots, providing another mechanism for seagrasses to alleviate sulphide stress globally.Subject terms: Microbial ecology, Plant ecology, Soil microbiology     

Leakage of adenylates during cold methanol/glycerol quenching of Escherichia coli

Effective and rapid inactivation of cellular metabolism is a prerequisite for accurate metabolome analysis. Cold methanol quenching is commonly applied to stop any metabolic activity and, at the same time remaining the cells’ integrity. However, it is reported that especially prokaryotic cells like Escherichia coli and Corynebacterium glutamicum tend to leak intracellular metabolites during cold methanol quenching. In this work leakage of adenylates is quantified for different quenching fluids. Further, a methanol/glycerol based quenching fluid is proposed, which reduces leakage drastically compared to the commonly applied methanol/water solution (16% ATP leakage compared to more than 70%).