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.     

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.     

Differential inhibition of glutamine and gamma-glutamylcysteine synthetases by alpha-alkyl analogs of methionine sulfoximine that induce convulsions.

The alpha-methyl and alpha-ethyl analogs of methionine sulfoximine, like methionine sulfoximine, induce convulsions in mice and inhibit glutamine synthetase irreversibly; alpha-ethylmethionine sulfoximine is approximately 50% as inhibitory as methionine sulfoximine and alpha-methylmethionine sulfoximine. However, whereas alpha-methylmethionine sulfoximine and methionine sulfoximine inhibit gamma-glutamylcysteine synthetase markedly, alpha-ethylmethionine sulfoximine does not, nor does administration of the alpha-ethyl analog produce the decrease in tissue glutathione levels found after giving methionine sulfoximine or its alpha-methyl analog. The findings strongly indicate that methionine sulfoximine-induced convulsions are closely associated with inhibition of glutamine synthetase rather than with inhibition of gamma-glutamylcysteine synthetase. The alpha-alkyl methionine sulfoximine analogs cannot be catabolized via the corresponding alpha-keto or alpha-imino acids, and, like other alpha-substituted amino acids, are probably not metabolized to a significant extent in vivo; this suggests that the amino acid sulfoximine molecules themselves, rather than their metabolites, are directly involved in the induction of convulsions. Possible explanations for the reported lack of correlation between the occurrence of convulsions and the levels of glutamine synthetase activity (and its substrates and product) are considered. The findings suggest that studies on the mechanism of induction of convulsions may be extended significantly and refined in biochemical terms by the use of other structurally modified convulsant molecules.     

Changes in auditory evoked brain potentials during ultra-low frequency whole-body vibration of man or of his visual surround

Auditory evoked brain potentials (AEP) were recorded from nine healthy male subjects during three types of condition: A - subject and visual field stationary; B - subject vibrated (z-axis, 0.6 Hz, 1.85 ms-2 rms), visual field stationary; C - subject stationary, visual field vibrated (as for B). The visual surround was confined to a checkerboard pattern in front of the subject. Auditory stimuli (1000 Hz, 86 dB, interstimulus interval 7 s) were delivered via headphones to evoke AEP. Vibration-synchronous activity in the EEG was eliminated by a subtraction technique. In comparison with condition A, conditions B and C caused an attenuation of P2 and N1P2 components of AEP together with an increased latency of N1. Effects of conditions B and C did not differ. Direct vestibular stimulation and mechanisms specific for whole-body vibration were rejected as modes of action. The AEP-changes and the subjective evaluation of experimental conditions, arousal and performance, as well as symptoms of kinetosis (motion sickness) suggest a sensory mismatch, leading to a "latent kinetosis" with de-arousal, as the dominating mechanism by which the processing of information was affected. This suggestion was supported by an additional pilot study. Under real working conditions a similar effect can be expected during relative motion between the driver and his visual surround, i.e. even with perfect vibro-isolation of the driver's seat.     

Protection against cisplatin toxicity by administration of glutathione ester

The role of cellular glutathione in the prevention of toxicity due to the anti-cancer drug cisplatin (cis-diamminedichloroplatinum) was explored in mice treated with buthionine sulfoximine (BSO), a selective inhibitor of gamma-glutamylcysteine synthetase (and therefore of glutathione synthesis), and with glutathione and glutathione monoisopropyl ester. Pretreatment of mice with BSO enhanced the lethal toxicity of cisplatin by about twofold. Administration of glutathione ester (dose, 2.5-7.5 mmol/kg) protected against lethal cisplatin toxicity; glutathione was also effective, but much less so. Glutathione ester, in contrast to glutathione, is effectively transported into cells and split to glutathione intracellularly. The previous findings that administered glutathione does not protect against lethal toxicity due to cadmium ions and mercuric ions, whereas glutathione ester does, suggest that intracellular glutathione is required for protection against these heavy metal ions. That administration of glutathione has a protective effect on cisplatin toxicity suggests that the toxic effects of cisplatin may be exerted both intracellularly and extracellularly, and that extracellular glutathione (or its degradation products) may form a complex with cisplatin extracellularly. The finding that glutathione ester is more effective than glutathione in protecting against the toxicity of cisplatin suggests that use of glutathione ester may be therapeutically advantageous.     

Evolutionary conservation of the human homologue of the yeast cell cycle control gene cdc2 and assignment of Cd2 to chromosome 10

Summary The human homologue of the fission yeast Schizosaccharomyces pombe cell cycle control gene cdc2 has been assigned to chromosome 10. DNA hybridization reveals that this gene is highly conserved in vertebrates. The human CDC2 gene probe detects a simple two-allele polymorphism in Taq1-digested DNA.