Morphological plasticity of motor axons in Drosophila mutants with altered excitability

An anatomical and electrophysiological study of Drosophila mutants has been made to determine the effect of altered electrical activity on the development and maintenance of larval neuromuscular junctions. We examined motor axon terminals of (1) hyperexcitable mutants Shaker (Sh), ether a go-go (eag), Hyperkinetic (Hk), and Duplication of para+ (Dp para+); and (2) mutants with reduced excitability, no action potential (napts) and paralytic (parats 1). Nerve terminals innervating larval body-wall muscles were visualized by using anti-HRP immunocytochemistry, which specifically stains neurons in insect species. In wild-type larvae, motor axon terminals were distributed in a stereotypic fashion. However, in combinations of eag and Sh alleles, the basic pattern of innervation was altered. There was an increase in both the number of higher-order axonal branches over the muscles and the number of varicosities on the neurites. A similar phenomenon was found in the double mutant Hk eag and, to a lesser extent, in Dp para+ and Dp para+ Sh mutants. It is known that at permissive temperature the napts, but not parats 1, mutation decreases excitability of larval motor axons and suppresses the behavioral phenotypes of Sh, eag, and Hk. In the mutant napts (reared at permissive temperature), a slight decrease in the extent of branching was observed. Yet, when combined with eag Sh, napts completely reversed the morphological abnormality in eag Sh mutants. No such reversion was observed in parats 1 eag Sh mutants. The endogenous patterns of electrical activity at the neuromuscular junction were analyzed by extracellular recordings in a semi-intact larval preparation. Recordings from wild-type body-wall muscles revealed rhythmic bursts of spikes. In eag Sh mutants, this rhythmic activity was accompanied by or superimposed on periods of strong tonic activity. This abnormal pattern of activity could be partially suppressed by napts in combination with eag Sh

Synaptic plasticity in Drosophila memory and hyperexcitable mutants: role of cAMP cascade

Activity-dependent synaptic plasticity has been implicated in the refinement and modification of neural circuits during development and learning. Previous studies show that activity-induced facilitation and potentiation are disrupted at larval neuromuscular junctions in the memory mutants dunce (dnc) and rutabaga (rut) of Drosophila. The diminished learning-memory capacity and synaptic transmission plasticity have been associated with altered cAMP levels since dnc affects the cAMP-specific phosphodiesterase and rut affects adenylate cyclase. In this study, the morphology of larval motor axon terminals was examined by anti-HRP immunohistochemistry. It was found that the numbers of terminal varicosities and branches were increased in dnc mutants, which have elevated cAMP concentrations. Such increase was suppressed in dnc rut double mutants by rut mutations, which reduce cAMP synthesis. More profuse projections of larval motor axons have also been reported in double-mutant combinations of ether a go-go (eag) and Shaker (Sh) alleles, which display greatly enhanced nerve activity as a result of reduction in different K+ currents. Therefore, we examined combinations of dnc and rut with eag and Sh mutations to explore the possible relation between activity- and cAMP-induced morphological changes. We found that the expanded projections in dnc were further enhanced in double mutants of dnc with either eag or Sh, an effect that could again be suppressed by rut. The results provide evidence for altered plasticity of synaptic morphology in memory mutants dnc and rut and suggest a role of cAMP cascade in mediating activity-dependent synaptic plasticity

INPOP08, a 4-D planetary ephemeris: From asteroid and time-scale computations to ESA Mars Express and Venus Express contributions

The latest version of the planetary ephemerides developed at the Paris Observatory and at the Besancon Observatory is presented here. INPOP08 is a 4-dimension ephemeris since it provides to users positions and velocities of planets and the relation between TT and TDB. Investigations leading to improve the modeling of asteroids are described as well as the new sets of observations used for the fit of INPOP08. New observations provided by the European Space Agency (ESA) deduced from the tracking of the Mars Express (MEX) and Venus Express (VEX) missions are presented as well as the normal point deduced from the Cassini mission. We show the huge impact brought by these observations in the fit of INPOP08, especially in terms of Venus, Saturn and Earth-Moon barycenter orbits.Comment: 14 pages. submitted to A&A. accepted in A&

Quantifying Condition-Dependent Intracellular Protein Levels Enables High-Precision Fitness Estimates

Countless studies monitor the growth rate of microbial populations as a measure of fitness. However, an enormous gap separates growth-rate differences measurable in the laboratory from those that natural selection can distinguish efficiently. Taking advantage of the recent discovery that transcript and protein levels in budding yeast closely track growth rate, we explore the possibility that growth rate can be more sensitively inferred by monitoring the proteomic response to growth, rather than growth itself. We find a set of proteins whose levels, in aggregate, enable prediction of growth rate to a higher precision than direct measurements. However, we find little overlap between these proteins and those that closely track growth rate in other studies. These results suggest that, in yeast, the pathways that set the pace of cell division can differ depending on the growth-altering stimulus. Still, with proper validation, protein measurements can provide high-precision growth estimates that allow extension of phenotypic growth-based assays closer to the limits of evolutionary selection

Performance of a cryogenic system prototype for the XENON1T Detector

We have developed an efficient cryogenic system with heat exchange and associated gas purification system, as a prototype for the XENON1T experiment. The XENON1T detector will use about 3 ton of liquid xenon (LXe) at a temperature of 175K as target and detection medium for a dark matter search. In this paper we report results on the cryogenic system performance focusing on the dynamics of the gas circulation-purification through a heated getter, at flow rates above 50 Standard Liter per Minute (SLPM). A maximum flow of 114 SLPM has been achieved, and using two heat exchangers in parallel, a heat exchange efficiency better than 96% has been measured

Influence of Preparative Form on the Target Efficiency and Toxicity of the Solid Insecticide Based on Pyrethroid and Neonicatinoid

Received: 24.11.2021. Revised: 11.01.2022. Accepted: 11.01.2022. Available online: 13.01.2022.The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.The influence of solid preparative form was studied on the «GET Dry» insecticide based on alpha-cypermethrin and imidacloprid. The target efficiency as acute and residual impact was studied when agent was applied against the bedbugs (Cimex hemipterus), German cockroach (Blatella germanica), common house flies (Musca domestica) and larvae of the leather beetles (Attagenus smirnovi). The agent demonstrated strong acute effect (about 100%) when applied against the cockroaches, bugs, and flies. Moreover, the agent demonstrates the residual impact on the cockroaches, flies, fleas for 45 days, and on the bugs for 30 days. The slight insecticidal activity was observed when the agent was applied against the larvae. We studied toxicity of the agent, LD50, when swallowed (moderately hazardous substances, class III) and when applied to the skin (low-hazard substance, class IV) as well as studied its inhalation hazard according to its volatility С 20 °C, irritant action when applied to the skin (slight) and eye irritation (moderate). Sensibilizing action was not observed

Explosive events - swirling transition region jets

In this paper, we extend our earlier work to provide additional evidence for an alternative scenario to explain the nature of so-called `explosive events'. The bi-directed, fast Doppler motion of explosive events observed spectroscopically in the transition region emission is classically interpreted as a pair of bidirectional jets moving upward and downward from a reconnection site. We discuss the problems of such a model. In our previous work, we focused basically on the discrepancy of fast Doppler motion without detectable motion in the image plane. We now suggest an alternative scenario for the explosive events, based on our observations of spectral line tilts and bifurcated structure in some events. Both features are indicative of rotational motion in narrow structures. We explain the bifurcation as the result of rotation of hollow cylindrical structures and demonstrate that such a sheath model can also be applied to explain the nature of the puzzling `explosive events'. We find that the spectral tilt, the lack of apparent motion, the bifurcation, and a rapidly growing number of direct observations support an alternative scenario of linear, spicular-sized jets with a strong spinning motion.Comment: 9 pages, 3 figures, accepted for publication in Solar Physic

Future research demands of the United European Gastroenterology (UEG) and its member societies

AIMS: The purpose of this study was to initiate and stimulate collaborative research efforts to support United European Gastroenterology Federation (UEG) member societies facilitating digestive health research in European on the one hand and, on the other hand, to increase EU-funded digestive health research by providing evidence and advice to funding bodies on priority areas. The UEG Research Committee initiated a survey of the current and future research interests of each individual UEG ordinary member society (specialist societies). METHODS: A questionnaire was sent by mail to 17 UEG ordinary member societies asking them to specify research demands related to the most urgent medical need including basic science research, translational research, clinical research, patient management research and research on disease prevention, in an open fashion but with limited word count. RESULTS: The responses from 13 societies were analysed in a semi-quantitative and in a qualitative way, and were clustered into five domains with two aspects each that were consented and shared between three and seven of the responding 13 societies. These clusters resemble topics such as ‘Hot topics’ (e.g. life-style, nutrition, microbial-host interaction), Biomarkers (genetic profiling, gut-brain interaction), Advanced technology (artificial intelligence, personalised medicine), Global research tools (bio-banking, EU trials), and Medical training (education, prevention). CONCLUSION: The generated topic list allows both collaboration between individual specialist societies as well as initiating and fostering future research calls at the EU level and beyond when approaching stakeholders

Glial wingless/Wnt regulates glutamate receptor clustering and synaptic physiology at the Drosophila neuromuscular junction

Glial cells are emerging as important regulators of synapse formation, maturation, and plasticity through the release of secreted signaling molecules. Here we use chromatin immunoprecipitation along with Drosophila genomic tiling arrays to define potential targets of the glial transcription factor Reversed polarity (Repo). Unexpectedly, we identified wingless (wg), a secreted morphogen that regulates synaptic growth at the Drosophila larval neuromuscular junction (NMJ), as a potential Repo target gene. We demonstrate that Repo regulates wg expression in vivo and that local glial cells secrete Wg at the NMJ to regulate glutamate receptor clustering and synaptic function. This work identifies Wg as a novel in vivo glial-secreted factor that specifically modulates assembly of the postsynaptic signaling machinery at the Drosophila NMJ