Chlamydia Hijacks ARF GTPases To Coordinate Microtubule Posttranslational Modifications and Golgi Complex Positioning.

The intracellular bacterium Chlamydia trachomatis develops in a parasitic compartment called the inclusion. Posttranslationally modified microtubules encase the inclusion, controlling the positioning of Golgi complex fragments around the inclusion. The molecular mechanisms by which Chlamydia coopts the host cytoskeleton and the Golgi complex to sustain its infectious compartment are unknown. Here, using a genetically modified Chlamydia strain, we discovered that both posttranslationally modified microtubules and Golgi complex positioning around the inclusion are controlled by the chlamydial inclusion protein CT813/CTL0184/InaC and host ARF GTPases. CT813 recruits ARF1 and ARF4 to the inclusion membrane, where they induce posttranslationally modified microtubules. Similarly, both ARF isoforms are required for the repositioning of Golgi complex fragments around the inclusion. We demonstrate that CT813 directly recruits ARF GTPases on the inclusion membrane and plays a pivotal role in their activation. Together, these results reveal that Chlamydia uses CT813 to hijack ARF GTPases to couple posttranslationally modified microtubules and Golgi complex repositioning at the inclusion.IMPORTANCEChlamydia trachomatis is an important cause of morbidity and a significant economic burden in the world. However, how Chlamydia develops its intracellular compartment, the so-called inclusion, is poorly understood. Using genetically engineered Chlamydia mutants, we discovered that the effector protein CT813 recruits and activates host ADP-ribosylation factor 1 (ARF1) and ARF4 to regulate microtubules. In this context, CT813 acts as a molecular platform that induces the posttranslational modification of microtubules around the inclusion. These cages are then used to reposition the Golgi complex during infection and promote the development of the inclusion. This study provides the first evidence that ARF1 and ARF4 play critical roles in controlling posttranslationally modified microtubules around the inclusion and that Chlamydia trachomatis hijacks this novel function of ARF to reposition the Golgi complex

The malleable brain: plasticity of neural circuits and behavior: A review from students to students

One of the most intriguing features of the brain is its ability to be malleable, allowing it to adapt continually to changes in the environment. Specific neuronal activity patterns drive long-lasting increases or decreases in the strength of synaptic connections, referred to as long-term potentiation (LTP) and long-term depression (LTD) respectively. Such phenomena have been described in a variety of model organisms, which are used to study molecular, structural, and functional aspects of synaptic plasticity. This review originated from the first International Society for Neurochemistry (ISN) and Journal of Neurochemistry (JNC) Flagship School held in Alpbach, Austria (Sep 2016), and will use its curriculum and discussions as a framework to review some of the current knowledge in the field of synaptic plasticity. First, we describe the role of plasticity during development and the persistent changes of neural circuitry occurring when sensory input is altered during critical developmental stages. We then outline the signaling cascades resulting in the synthesis of new plasticity-related proteins, which ultimately enable sustained changes in synaptic strength. Going beyond the traditional understanding of synaptic plasticity conceptualized by LTP and LTD, we discuss system-wide modifications and recently unveiled homeostatic mechanisms, such as synaptic scaling. Finally, we describe the neural circuits and synaptic plasticity mechanisms driving associative memory and motor learning. Evidence summarized in this review provides a current view of synaptic plasticity in its various forms, offers new insights into the underlying mechanisms and behavioral relevance, and provides directions for future research in the field of synaptic plasticity.Fil: Schaefer, Natascha. University of Wuerzburg; AlemaniaFil: Rotermund, Carola. University of Tuebingen; AlemaniaFil: Blumrich, Eva Maria. Universitat Bremen; AlemaniaFil: Lourenco, Mychael V.. Universidade Federal do Rio de Janeiro; BrasilFil: Joshi, Pooja. Robert Debre Hospital; FranciaFil: Hegemann, Regina U.. University of Otago; Nueva ZelandaFil: Jamwal, Sumit. ISF College of Pharmacy; IndiaFil: Ali, Nilufar. Augusta University; Estados UnidosFil: García Romero, Ezra Michelet. Universidad Veracruzana; MéxicoFil: Sharma, Sorabh. Birla Institute of Technology and Science; IndiaFil: Ghosh, Shampa. Indian Council of Medical Research; IndiaFil: Sinha, Jitendra K.. Indian Council of Medical Research; IndiaFil: Loke, Hannah. Hudson Institute of Medical Research; AustraliaFil: Jain, Vishal. Defence Institute of Physiology and Allied Sciences; IndiaFil: Lepeta, Katarzyna. Polish Academy of Sciences; ArgentinaFil: Salamian, Ahmad. Polish Academy of Sciences; ArgentinaFil: Sharma, Mahima. Polish Academy of Sciences; ArgentinaFil: Golpich, Mojtaba. University Kebangsaan Malaysia Medical Centre; MalasiaFil: Nawrotek, Katarzyna. University Of Lodz; ArgentinaFil: Paid, Ramesh K.. Indian Institute of Chemical Biology; IndiaFil: Shahidzadeh, Sheila M.. Syracuse University; Estados UnidosFil: Piermartiri, Tetsade. Universidade Federal de Santa Catarina; BrasilFil: Amini, Elham. University Kebangsaan Malaysia Medical Centre; MalasiaFil: Pastor, Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia ; ArgentinaFil: Wilson, Yvette. University of Melbourne; AustraliaFil: Adeniyi, Philip A.. Afe Babalola University; NigeriaFil: Datusalia, Ashok K.. National Brain Research Centre; IndiaFil: Vafadari, Benham. Polish Academy of Sciences; ArgentinaFil: Saini, Vedangana. University of Nebraska; Estados UnidosFil: Suárez Pozos, Edna. Instituto Politécnico Nacional; MéxicoFil: Kushwah, Neetu. Defence Institute of Physiology and Allied Sciences; IndiaFil: Fontanet, Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Biología Celular y Neurociencia ; ArgentinaFil: Turner, Anthony J.. University of Leeds; Reino Unid

Ticagrelor effectively inhibits platelet aggregation in comatose survivors of cardiac arrest undergoing primary percutaneous coronary intervention treated with mild therapeutic hypothermia

Background: Mild therapeutic hypothermia (MTH) is believed to reduce the effectiveness of antiplatelet drugs. Effective dual-antiplatelet therapy after percutaneous coronary intervention (PCI) is mandatory to avoid acute stent thrombosis (ST). The effectiveness of ticagrelor in MTH-treated out-of-hospital cardiac arrest (OHCA) survivors is still a matter of debate. The aim of the study was to evaluate the impact of MTH on the platelet-inhibitory effect of ticagrelor in comatose survivors of OHCA treated with primary PCI. Methods: Eighteen comatose survivors of OHCA with acute coronary syndrome undergoing immediate PCI treated with MTH were compared with 14 patients with uncomplicated primary myocardial infarction after PCI, matched for gender and age, in a prospective, single-center, observational study. Platelet aggregation was evaluated using VerifyNow P2Y12 point-of-care testing at 3 time points: admission (T0), during MTH (T1), and 48–72 h after rewarming (T2). Results: Ticagrelor effectively inhibits platelet aggregation in OHCA patients subjected to MTH and in all patients in the control group. The effectiveness of ticagrelor did not differ between the MTH group and the control group (p = 0.581). In 2 cases in the MTH population, the platelet response to ticagrelor was inadequate, and in one of them it remained insufficient during the re-warming phase. There was no stent thrombosis in these patients. Conclusions: The present study confirmed the effectiveness of ticagrelor to inhibit platelets in myocardial infarction patients after OHCA treated with primary PCI undergoing hypothermia. The use of cooling was not associated with an increased risk of stent thrombosis

A two-site flexible clamp mechanism for RET-GDNF-GFRα1 assembly reveals both conformational adaptation and strict geometric spacing

RET receptor tyrosine kinase plays vital developmental and neuroprotective roles in metazoans. GDNF family ligands (GFLs) when bound to cognate GFRα co-receptors recognize and activate RET stimulating its cytoplasmic kinase function. The principles for RET ligand-co-receptor recognition are incompletely understood. Here, we report a crystal structure of the cadherin-like module (CLD1-4) from zebrafish RET revealing interdomain flexibility between CLD2 and CLD3. Comparison with a cryo-electron microscopy structure of a ligand-engaged zebrafish RETECD-GDNF-GFRα1a complex indicates conformational changes within a clade-specific CLD3 loop adjacent to the co-receptor. Our observations indicate that RET is a molecular clamp with a flexible calcium-dependent arm that adapts to different GFRα co-receptors, while its rigid arm recognizes a GFL dimer to align both membrane-proximal cysteine-rich domains. We also visualize linear arrays of RETECD-GDNF-GFRα1a suggesting that a conserved contact stabilizes higher-order species. Our study reveals that ligand-co-receptor recognition by RET involves both receptor plasticity and strict spacing of receptor dimers by GFL ligands

Microtubule structure by cryo-EM: snapshots of dynamic instability

The development of cryo-electron microscopy (cryo-EM) allowed microtubules to be captured in their solution-like state, enabling decades of insight into their dynamic mechanisms and interactions with binding partners. Cryo-EM micrographs provide 2D visualization of microtubules, and these 2D images can also be used to reconstruct the 3D structure of the polymer and any associated binding partners. In this way, the binding sites for numerous components of the microtubule cytoskeleton - including motor domains from many kinesin motors, and the microtubule-binding domains of dynein motors and an expanding collection of microtubule associated proteins - have been determined. The effects of various microtubule-binding drugs have also been studied. High resolution cryo-EM structures have also been used to probe the molecular basis of microtubule dynamic instability, driven by the GTPase activity of β-tubulin. These studies have shown the conformational changes in lattice-confined tubulin dimers in response to steps in the tubulin GTPase cycle, most notably lattice compaction at the longitudinal inter-dimer interface. Although work is ongoing to define a complete structural model of dynamic instability, attention has focused on the role of gradual destabilization of lateral contacts between tubulin protofilaments, particularly at the microtubule seam. Furthermore, lower resolution cryo-electron tomography 3D structures are shedding light on the heterogeneity of microtubule ends and how their 3D organization contributes to dynamic instability. The snapshots of these polymers captured using cryo-EM will continue to provide critical insights into their dynamics, interactions with cellular components, and the way microtubules contribute to cellular functions in diverse physiological contexts

Investigation of Parameters Influencing Tubular-Shaped Chitosan-Hydroxyapatite Layer Electrodeposition

Tubular-shaped layer electrodeposition from chitosan-hydroxyapatite colloidal solutions has found application in the field of regeneration or replacement of cylindrical tissues and organs, especially peripheral nerve tissue regeneration. Nevertheless, the quantitative and qualitative characterisation of this phenomenon has not been described. In this work, the colloidal systems are subjected to the action of an electric current initiated at different voltages. Parameters of the electrodeposition process (i.e., total charge exchanged, gas volume, and deposit thickness) are monitored over time. Deposit structures are investigated by scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The value of voltage influences structural characteristics but not thickness of deposit for the process lasting at least 20 min. The calculated number of exchanged electrons for studied conditions suggests that the mechanism of deposit formation is governed not only by water electrolysis but also interactions between formed hydroxide ions and calcium ions coordinated by chitosan chains

Adsorption processes in forming of hybrid structures for controlled release of pharmaceuticals

Przedstawiono możliwości wytwarzania układów hybrydowych do kontrolowanego uwalniania środków farmakologicznych przy wykorzystaniu nośników hydrożelowych i struktury w skali mikro i nano. Szczególną uwagę zwrócono na wytwarzanie takich układów w procesie adsorpcji, korzystając z nośnika chitozanowego. Przedstawiono modele opisujące stan równowagi oraz kinetykę w procesie sorpcji substancji modelowych.Possibilities of formation of hybrid systems for controlled drug release from hydrogel carriers and structures in micro- and nanoscale are discussed in the study. Attention is focussed on the formation of such systems in the adsorption process from a chitosan carrier. Models which describe the equilibrium state and sorption kinetics of model substances are presented

The presence of anti-Yersinia pseudotuberculosis immunoglobulins in equine serum

The research was conducted on clinically healthy mares (n=40) and foals (n=78) duringY. pseudotuberculosis associated enzootics. The animals were divided into groups: I to IV – mares, IA to IVA – their offsprings, IB to IVB – foals which mothers were not treated with any medicaments. The animals in group I, IA and IB were injected with PBS; in group II, IIA and IIB – with Y. pseudotuberculosis strain-based vaccine, in group III, IIIA and IIIB – with P. acnes strain-based immunostimulator; in group IV, IVA and IVB – with P. acnes strain-based immunostimulator and (5 days after the immunostimulator injection)Y. pseudotuberculosis strain-based vaccine. The presence of antibodies was determined by means of ELISA. The study revealed anti-Yersinia pseudotuberculosis IgG only in 19 mares before, and in 25 mares and 26 foals 3 weeks after vaccination. The mean extinction 3 weeks after vaccination amounted to: II-0.489, IV-2.578, IIA-0.572, IVA-0.974, IIB-0.312, IVB-0.418. The cut-off extinction value was 0.154. The presence of anti-Yersinia pseudotuberculosis IgG before vaccination in the sera of clinically healthy mares may suggest that Y. pseudotuberculosis infection occurs definitely more often than is expected. Vaccination preceded by immunostimulation appeared to be the most efficient method of treatment against yersiniosis

Molecular typing of Staphylococcus aureus based on PCR-RFLP of coa gene and RAPD analysis

The aim of this study was molecular identification of S. aureus strains isolated from mastitic milk samples and establishing the genetic relationship between strains isolated from cows belonging to the same herd. In all 43 isolated strains the gap gene (930 bp) was amplified, which enabled their affiliation to the Staphylococcus genus to be established. PCR-RFLP with AluI endonuclease of the gap gene as well as nuc (450 bp) and coa (1130 bp) gene amplification allowed precise S. aureus species identification. One hundred percent of the genetic relationship between strains was established via RAPD-PCR and coa-typing