Octopamine underlies the counter-regulatory response to a glucose deficit in honeybees (Apis mellifera)

An animal’s internal state is a critical parameter required for adaptation to a given environment. An important aspect of an animal’s internal state is the energy state that is adjusted to the needs of an animal by energy homeostasis. Glucose is one essential source of energy, especially for the brain. A shortage of glucose therefore triggers a complex response to restore the animal’s glucose supply. This counter-regulatory response to a glucose deficit includes metabolic responses like the mobilization of glucose from internal glucose stores and behavioral responses like increased foraging and a rapid intake of food. In mammals, the catecholamines adrenalin and noradrenalin take part in mediating these counter-regulatory responses to a glucose deficit. One candidate molecule that might play a role in these processes in insects is octopamine (OA). It is an invertebrate biogenic amine and has been suggested to derive from an ancestral pathway shared with adrenalin and noradrenalin. Thus, it could be hypothesized that OA plays a role in the insect’s counter- regulatory response to a glucose deficit. Here we tested this hypothesis in the honeybee (Apis mellifera), an insect that, as an adult, mainly feeds on carbohydrates and uses these as its main source of energy. We investigated alterations of the hemolymph glucose concentration, survival, and feeding behavior after starvation and examined the impact of OA on these processes in pharmacological experiments. We demonstrate an involvement of OA in these three processes in honeybees and conclude there is an involvement of OA in regulating a bee’s metabolic, physiological, and behavioral response following a phase of prolonged glucose deficit. Thus, OA in honeybees acts similarly to adrenalin and noradrenalin in mammals in regulating an animal’s counter- regulatory response

Nanometer precise adjustment of the silver shell thickness during automated Au-Ag core-shell nanoparticle synthesis in micro fluid segment sequences

In this work, a wet-chemical synthesis method for gold–silver core–shell particles with nanometer precise adjustable silver shell thicknesses is presented. Typically wet-chemical syntheses lead to relatively large diameter size distributions and losses in the yield of the desired particle structure due to thermodynamical effects. With the here explained synthesis method in micro fluidic segment sequences, a combinatorial in situ parameter screening of the reactant concentration ratios by programmed flow rate shifts in conjunction with efficient segment internal mixing conditions is possible. The highly increased mixing rates ensure a homogeneous shell deposition on all presented gold core particles while the amount of available silver ions was adjusted by automated flow rate courses, from which the synthesis conditions for exactly tunable shell thicknesses between 1.1 and 6.1 nm could be derived. The findings according to the homogeneity of size and particle structure were confirmed by differential centrifugal sedimentation (DCS), scanning and transmission electron microscopy (SEM, TEM) and X-ray photoelectron spectroscopy (XPS) measurements. In UV-Vis measurements, a significant contribution of the core metal was found in the shape of the extinction spectra in the case of thin shells. These results were confirmed by theoretical calculations

Strong negative feedback from Erk to Raf confers robustness to MAPK signalling

This study shows that MAPK signalling is robust against protein level changes due to a strong negative feedback from Erk to Raf. Surprisingly, robustness is provided through a fast post-translational mechanism although variation of Erk levels occurs on a timescale of days

Phospho-proteomic analyses of B-Raf protein complexes reveal new regulatory principles

B-Raf represents a critical physiological regulator of the Ras/RAF/MEK/ERK-pathway and a pharmacological target of growing clinical relevance, in particular in oncology. To understand how B-Raf itself is regulated, we combined mass spectrometry with genetic approaches to map its interactome in MCF-10A cells as well as in B-Raf deficient murine embryonic fibroblasts (MEFs) and B-Raf/Raf-1 double deficient DT40 lymphoma cells complemented with wildtype or mutant B-Raf expression vectors. Using a multi-protease digestion approach, we identified a novel ubiquitination site and provide a detailed B-Raf phospho-map. Importantly, we identify two evolutionary conserved phosphorylation clusters around T401 and S419 in the B-Raf hinge region. SILAC labelling and genetic/biochemical follow-up revealed that these clusters are phosphorylated in the contexts of oncogenic Ras, sorafenib induced Raf dimerization and in the background of the V600E mutation. We further show that the vemurafenib sensitive phosphorylation of the T401 cluster occurs in trans within a Raf dimer. Substitution of the Ser/Thr-residues of this cluster by alanine residues enhances the transforming potential of B-Raf, indicating that these phosphorylation sites suppress its signaling output. Moreover, several B-Raf phosphorylation sites, including T401 and S419, are somatically mutated in tumors, further illustrating the importance of phosphorylation for the regulation of this kinase

Multidifferential study of identified charged hadron distributions in ZZ-tagged jets in proton-proton collisions at s=\sqrt{s}=13 TeV

Jet fragmentation functions are measured for the first time in proton-proton collisions for charged pions, kaons, and protons within jets recoiling against a $Z$ boson. The charged-hadron distributions are studied longitudinally and transversely to the jet direction for jets with transverse momentum 20 $< p_{\textrm{T}} < 100$ GeV and in the pseudorapidity range $2.5 < \eta < 4$. The data sample was collected with the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 1.64 fb$^{-1}$. Triple differential distributions as a function of the hadron longitudinal momentum fraction, hadron transverse momentum, and jet transverse momentum are also measured for the first time. This helps constrain transverse-momentum-dependent fragmentation functions. Differences in the shapes and magnitudes of the measured distributions for the different hadron species provide insights into the hadronization process for jets predominantly initiated by light quarks.Comment: All figures and tables, along with machine-readable versions and any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-013.html (LHCb public pages

Study of the B−→Λc+Λˉc−K−B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-} decay

The decay $B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-}$ is studied in proton-proton collisions at a center-of-mass energy of $\sqrt{s}=13$ TeV using data corresponding to an integrated luminosity of 5 $\mathrm{fb}^{-1}$ collected by the LHCb experiment. In the $\Lambda_{c}^+ K^{-}$ system, the $\Xi_{c}(2930)^{0}$ state observed at the BaBar and Belle experiments is resolved into two narrower states, $\Xi_{c}(2923)^{0}$ and $\Xi_{c}(2939)^{0}$, whose masses and widths are measured to be $$m(\Xi_{c}(2923)^{0}) = 2924.5 \pm 0.4 \pm 1.1 \,\mathrm{MeV}, \\ m(\Xi_{c}(2939)^{0}) = 2938.5 \pm 0.9 \pm 2.3 \,\mathrm{MeV}, \\ \Gamma(\Xi_{c}(2923)^{0}) = \phantom{000}4.8 \pm 0.9 \pm 1.5 \,\mathrm{MeV},\\ \Gamma(\Xi_{c}(2939)^{0}) = \phantom{00}11.0 \pm 1.9 \pm 7.5 \,\mathrm{MeV},$$ where the first uncertainties are statistical and the second systematic. The results are consistent with a previous LHCb measurement using a prompt $\Lambda_{c}^{+} K^{-}$ sample. Evidence of a new $\Xi_{c}(2880)^{0}$ state is found with a local significance of $3.8\,\sigma$, whose mass and width are measured to be $2881.8 \pm 3.1 \pm 8.5\,\mathrm{MeV}$ and $12.4 \pm 5.3 \pm 5.8 \,\mathrm{MeV}$, respectively. In addition, evidence of a new decay mode $\Xi_{c}(2790)^{0} \to \Lambda_{c}^{+} K^{-}$ is found with a significance of $3.7\,\sigma$. The relative branching fraction of $B^{-} \to \Lambda_{c}^{+} \bar{\Lambda}_{c}^{-} K^{-}$ with respect to the $B^{-} \to D^{+} D^{-} K^{-}$ decay is measured to be $2.36 \pm 0.11 \pm 0.22 \pm 0.25$, where the first uncertainty is statistical, the second systematic and the third originates from the branching fractions of charm hadron decays.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-028.html (LHCb public pages

Measurement of the ratios of branching fractions R(D∗)\mathcal{R}(D^{*}) and R(D0)\mathcal{R}(D^{0})

The ratios of branching fractions $\mathcal{R}(D^{*})\equiv\mathcal{B}(\bar{B}\to D^{*}\tau^{-}\bar{\nu}_{\tau})/\mathcal{B}(\bar{B}\to D^{*}\mu^{-}\bar{\nu}_{\mu})$ and $\mathcal{R}(D^{0})\equiv\mathcal{B}(B^{-}\to D^{0}\tau^{-}\bar{\nu}_{\tau})/\mathcal{B}(B^{-}\to D^{0}\mu^{-}\bar{\nu}_{\mu})$ are measured, assuming isospin symmetry, using a sample of proton-proton collision data corresponding to 3.0 fb${ }^{-1}$ of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode $\tau^{-}\to\mu^{-}\nu_{\tau}\bar{\nu}_{\mu}$. The measured values are $\mathcal{R}(D^{*})=0.281\pm0.018\pm0.024$ and $\mathcal{R}(D^{0})=0.441\pm0.060\pm0.066$, where the first uncertainty is statistical and the second is systematic. The correlation between these measurements is $\rho=-0.43$. Results are consistent with the current average of these quantities and are at a combined 1.9 standard deviations from the predictions based on lepton flavor universality in the Standard Model.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-039.html (LHCb public pages

Characterisation of the electronic and chemical properties of as-grown polar InN surfaces and their changes during the interaction with adsorbates

Indium nitride (InN) is a III-V semiconductor and due to its low band gap and good electron transport properties a promising candidate for applications in ultrafast transistor and optoelectronic devices. In this context, not only the bulk but also the surface properties of the material are of major interest.This thesis is devoted to the investigation of the electronic and chemical surface properties of as-grown as well as adsorbate covered, polar InN. The InN layers were grown by plasma-assisted molecular beam epitaxy (MBE) and in-situ characterised by Reflection High Energy Electron Diffraction (RHEED) as well as X-ray and Ultraviolet Photoelectron Spectroscopy (XPS, UPS). The experimental results imply clear differences in the electronic properties of the polar surfaces due to differences of the atomic structure. At the In-polar InN surface, a 2×2 reconstruction, connected with surface states at the Fermi level is responsible for a strong electron accumulation at these InN(0001)- 2×2 surfaces. In contrast, N-polar InN shows a 1×1 surface with occupied surface states at the valence band maximum (at ~ 1,6 eV), connected with a considerably reduced surface downward band bending. Furthermore, changes of the InN surface properties due to adsorbate interaction were systematically studied using UPS and XPS with a special focus on the influence of oxygen and water as important components of the ambient air. The experimental results were discussed with regard to adsorbate bonding, dipole layer formation as well as changes in the surface band bending.Thereby, oxygen atomically bonds to the InN surfaces, acting as electron acceptor and reducing the surface downward band bending of the In-polar InN, while almost no change of the already reduced band bending at N-polar InN is observed. However, the interaction with water results in a strong downward band bending and electron accumulation for both polarities.Indiumnitrid (InN) gehört zu den III-V Halbleitern und ist durch seine geringe Bandlücke sowie seine guten Elektronentransporteigenschaften ein vielversprechender Kandidat für den Einsatz in ultraschnellen Transistoren und optoelektronischen Bauelementen. Dabei spielen neben den Volumeneigenschaften des Materials vor allem auch die Oberflächeneigenschaften eine entscheidende Rolle. Die vorliegende Arbeit beschäftigt sich mit der Charakterisierung der elektronischen und chemischen Oberflächeneigenschaften von reinem sowie adsorbatbedecktem, polarem InN. Die InN-Schichten wurden mittels plasmaunterstützter Molekularstrahlepitaxie (MBE) abgeschieden und in-situ anhand der Beugung hochenergetischer Elektronen (RHEED) sowie mittels Röntgen- und Ultraviolett-Photoelektronenspektroskopie (XPS, UPS) untersucht. Hierbei zeigten sich deutliche Unterschiede in den elektronischen Eigenschaften der polaren Oberflächen, die vor allem auf die unterschiedlichen atomaren Strukturen zurückgeführt werden konnten. So kommt es an der In-polaren InN-Oberfläche zur Ausbildung einer 2×2 Oberflächenrekonstruktion, die zu Oberflächenzuständen nahe des Ferminiveaus führen, welche zur Ausbildung einer starken Elektronenakkumulationsschicht an den InN(0001)-2×2 Oberflächen beitragen. Beim reinen N-polaren InN beobachtet man im Gegensatz dazu eine 1×1-Oberfläche mit besetzten Oberflächenzuständen nahe des Valenzbandminimums (bei ~ 1,6 eV), verbunden mit einer deutlich reduzierten Oberflächenabwärtsbandverbiegung. Weiterhin wurden Veränderungen der InN-Oberflächen durch Adsorbatwechselwirkungen systematisch mittels UPS und XPS untersucht und dabei der Einfluss des Sauerstoffs und des Wassers als wichtige Bestandteile der Luft detailliert betrachtet. Die experimentellen Ergebnisse werden im Hinblick auf Informationen zur Anbindung der Adsorbatspezies, zur Dipolbildung sowie zur Beeinflussung der Oberflächenelektronen und damit der Oberflächenbandverbiegung der InN-Proben diskutiert. Dabei zeigt sich, dass Sauerstoff in atomarer Form an die InN-Oberflächen bindet und als Elektronenakzeptor zur Reduzierung der Abwärtsbandverbiegung an den In-polaren InN-Proben beiträgt bzw. kaum einen Einfluss auf die bereits reduzierte Bandverbiegung des N-polaren InN hat. Die Wechselwirkung mit Wasser führt dagegen bei beiden Polaritäten zu einer deutlich ausgeprägten Elektronenakkumulation