Presynaptic CK2 promotes synapse organization and stability by targeting Ankyrin2

The precise regulation of synapse maintenance is critical to the development and function of neuronal circuits. Using an in vivo RNAi screen targeting the Drosophila kinome and phosphatome, we identify 11 kinases and phosphatases controlling synapse stability by regulating cytoskeletal, phospholipid, or metabolic signaling. We focus on casein kinase 2 (CK2) and demonstrate that the regulatory (β) and catalytic (α) subunits of CK2 are essential for synapse maintenance. CK2α kinase activity is required in the presynaptic motoneuron, and its interaction with CK2β, mediated cooperatively by two N-terminal residues of CK2α, is essential for CK2 holoenzyme complex stability and function in vivo. Using genetic and biochemical approaches we identify Ankyrin2 as a key presynaptic target of CK2 to maintain synapse stability. In addition, CK2 activity controls the subcellular organization of individual synaptic release sites within the presynaptic nerve terminal. Our study identifies phosphorylation of structural synaptic components as a compelling mechanism to actively control the development and longevity of synaptic connections.     

2-Deoxy-D-galactose metabolism in ascites hepatoma cells results in phosphate trapping and glycolysis inhibition.

The metabolism of 2-deoxy-D-galactose has been studied in AS-30D rat ascites hepatoma cells in suspension. Using 2-deoxy-D-(1-14C)galactose and an alkaline ethanol deproteinization procedure, the quantitatively identified metabolites included 2-deoxy-D-galactose 1-phosphate comprising 99.3%, and UDP-2-deoxy-D-galactose and UDP-2-deoxy-D-glucose, together amounting to 0.4% of the total metabolites. After incubation for 5 h in the presence of 2-deoxy-D-galactose (1 mmo1/1), the content of 2-deoxy-D-galactose 1-phosphate reached 35 mmo1x(kg cells)-1. The rate of phosphorylation of 2-deoxy-D-galactose was rapid during the first 30 min and decreased to approximately 20% of this rate during the subsequent hours. The rapid trapping of Pi in the form of 2-deoxy-D-galactose 1-phosphate resulted in a depression of free intracellular Pi in spite of a concomitant increase in net 32Pi uptake from the medium and a decrease of ATP and other 5'-nucleotides. The rates of glucose utilization and lactate production were depressed by more than 80% in the presence of 2-deoxy-D-galactose (1 mmo1/1). Interruption of Pi trapping by removal of 2-deoxy-D-galactose from the medium reversed the depressions of Pi and ATP and resulted in a rapid but incomplete relief of glycolysis inhibition. Crossover analysis of glycolytic intermediates indicated an inhibition at the 6-phosphofructokinase step. The depression of glucose utilization may be mediated by the increased level of glucose 6-phosphate, a potent inhibitor of hexokinase. An additional inhibitory effect of a metabolite of 2-deoxy-D-galactose at the 6-phosphofructokinase step was indicated by crossover analysis after reversal of Pi and ATP depressions in the presence of a high intracellular content of 2-deoxy-D-glactose 1-phosphate. The quantitative analysis of the metabolites of 2-deoxy-D-galactose demonstrated the predominance of the monophosphate and the negligible formation of UPD derivatives of this sugar analog in AS-30D hepatoma cells. This provides a system for the investigation of a galactose analog as a phosphate-trapping agent in the virtual absence of uridylate trapping.     

Preadapted for invasiveness: do species traits or their plastic response to shading differ between invasive and non‐invasive plant species in their native range?

Aim Species capable of vigorous growth under a wide range of environmental conditions should have a higher chance of becoming invasive after introduction into new regions. High performance across environments can be achieved either by constitutively expressed traits that allow for high resource uptake under different environmental conditions or by adaptive plasticity of traits. Here we test whether invasive and non‐invasive species differ in presumably adaptive plasticity. Location Europe (for native species); the rest of the world and North America in particular (for alien species). Methods We selected 14 congeneric pairs of European herbaceous species that have all been introduced elsewhere. One species of each pair is highly invasive elsewhere in the world, particularly so in North America, whereas the other species has not become invasive or has spread only to a limited degree. We grew native plant material of the 28 species under shaded and non‐shaded conditions in a common garden experiment, and measured biomass production and morphological traits that are frequently related to shade tolerance and avoidance. Results Invasive species had higher shoot–root ratios, tended to have longer leaf‐blades, and produced more biomass than congeneric non‐invasive species both under shaded and non‐shaded conditions. Plants responded to shading by increasing shoot–root ratios and specific leaf area. Surprisingly, these shade‐induced responses, which are widely considered to be adaptive, did not differ between invasive and non‐invasive species. Main conclusions We conclude that high biomass production across different light environments pre‐adapts species to become invasive, and that this is not mediated by plasticities of the morphological traits that we measured.     

Stabilization of DNA triple helices by a series of mono- and disubstituted amidoanthraquinones.

We have used quantitative DNase I footprinting to measure the relative affinities of four disubstituted and two monosubstituted amidoanthraquinone compounds for intermolecular DNA triplexes, and have examined how the position of the attached base-functionalized substituents affects their ability to stabilize DNA triplexes. All four isomeric disubstituted derivatives examined stabilize DNA triplexes at micromolar or lower concentrations. Of the compounds studied the 2,7-disubstituted amidoanthraquinone displayed the greatest triplex affinity. The order of triplex affinity for the other disubstituted ligands decreases in the order 2,7 > 1,8 = 1,5 > 2,6, with the equivalent monosubstituted compounds being at least an order of magnitude less efficient. The 1,5-disubstituted derivative also shows some interaction with duplex DNA. These results have been confirmed by molecular modelling studies, which provide a rational basis for the structure-activity relationships. These suggest that, although all of the compounds bind through an intercalative mode, the 2,6, 2,7 and 1,5 disubstituted isomers bind with their two side groups occupying adjacent triplex grooves, in contrast with the 1,8 isomer which is positioned with both side groups in the same triplex groove.