Microtubule depolymerization affects endocytosis and exocytosis in the tip and influences endosome movement in tobacco pollen tubes

Polarized organization of the cytoplasm of growing pollen tubes is maintained by coordinated function of actin filaments (AFs) and microtubules (MTs). AFs convey post-Golgi secretory vesicles to the tip where some fuse with specific domains of the plasma membrane (PM). Secretory activity is balanced by PM retrieval that maintains cell membrane economy and regulates the polarized composition of the PM, by dividing lipids/proteins between the shank and the tip. Although AFs play a key role in PM internalization in the shank, the role of MTs in exoendocytosis needs to be characterized. The present results show that integrity of the MT cytoskeleton is necessary to control exoendocytosis events in the tip. MT polymerization plays a role in promoting PM invagination in the apex of tobacco pollen tubes since Nocodazole affected PM internalization in the tip and subsequent migration of endocytic vesicles from the apex for degradation. MT depolymerization in the apex and shank was associated with misallocation of a significantly greater amount of internalized PM to the Golgi apparatus and its early recycling to the secretory pathway. FRAP experiments also showed that MT depolymerization in the tip region influenced the rate of exocytosis in the central domain of the apical PM

Design and Experimental Characterization of a Niti-Based, High-Frequency, Centripetal Peristaltic Actuator

Development and experimental testing of a peristaltic device actuated by a single shape-memory NiTi wire are described. The actuator is designed to radially shrink a compliant silicone pipe, and must work on a sustained basis at an actuation frequency that is higher than those typical of NiTi actuators. Four rigid, aluminum-made circular sectors are sitting along the pipe circumference and provide the required NiTi wire housing. The aluminum assembly acts as geometrical amplifier of the wire contraction and as heat sink required to dissipate the thermal energy of the wire during the cooling phase. We present and discuss the full experimental investigation of the actuator performance, measured in terms of its ability to reduce the pipe diameter, at a sustained frequency of 1.5 Hz. Moreover, we investigate how the diameter contraction is affected by various design parameters as well as actuation frequencies up to 4 Hz. We manage to make the NiTi wire work at 3% in strain, cyclically providing the designed pipe wall displacement. The actuator performance is found to decay approximately linearly with actuation frequencies up to 4 Hz. Also, the interface between the wire and the aluminum parts is found to be essential in defining the functional performance of the actuator

Transitions in morphologies, fluid regimes, and feeding mechanisms during development of the medusa Lychnorhiza lucerna

Author Posting. © The Author(s), 2016. This is the author's version of the work. It is posted here by permission of Inter-Research for personal use, not for redistribution. The definitive version was published in Marine Ecology Progress Series 557 (2016): 145-159, doi:10.3354/meps11855.The early ontogeny of scyphomedusae involves morphological and functional transitions in body plans that affect the predators’ propulsive and feeding strategies. We applied high-speed videography, digital particle image velocimetry (DPIV) and dye visualization techniques to evaluate alterations in swimming and feeding mechanisms during ontogeny of the rhizostome medusa Lychnorhiza lucerna Haeckel, 1880 (Scyphozoa, Rhizostomeae). During early ontogeny, the ephyral mouth lips develop into complex filtering structures along the oral arms. The viscous environments (Reynolds number <100) experienced by ephyrae constrain the feeding mechanisms that transport fluid during ephyral bell pulsations. In contrast, adult medusan fluid flows are dominated by inertial forces and bell pulsations effectively transport fluids and entrained prey toward the oral arms. The oral arm surfaces are covered by motile epidermal cilia that drive these entrained flows through filtering gaps in the oral arms where food particles are retained. In addition to this process within the oral arms, vortices generated during bell pulsation flow downstream along the outside of the medusae and continuously transport prey toward the exterior oral arm surfaces. Although calanoid copepods are capable of escape velocities that greatly exceed L. lucerna’s feeding current speeds, copepods often fail to detect the predator’s feeding currents or inadvertently jump into medusan capture surfaces during failed escape attempts. Consequently, the comparatively weak predator feeding currents successfully capture a portion of the copepods encountered by swimming medusae. These results clarify the processes that enable rhizostome medusae to play key roles as consumers in tropical and subtropical coastal environments.The study was partially funded by grants 2011/00436-8, 2013/19478-8, and 2014/00824-6 São Paulo Research Foundation (FAPESP), and CAPES PROEX2017-09-2

Restricted O2 consumption in pea roots induced by hexanoic acid is linked to depletion of Krebs cycle substrates

Plant roots are exposed to hypoxia in waterlogged soils, and they are further challenged by specific phytotoxins produced by microorganisms in such conditions. One such toxin is hexanoic acid (HxA), which, at toxic levels, causes a strong decline in root O2 consumption. However, the mechanism underlying this process is still unknown. We treated pea (Pisum sativum L.) roots with 20 mM HxA at pH 5.0 and 6.0 for a short time (1 h) and measured leakage of key electrolytes such as metal cations, malate, citrate and nonstructural carbohydrates (NSC). After treatment, mitochondria were isolated to assess their functionality evaluated as electrical potential and O2 consumption rate. HxA treatment resulted in root tissue extrusion of K+, malate, citrate and NSC, but only the leakage of the organic acids and NSC increased at pH 5.0, concomitantly with the inhibition of O2 consumption. The activity of mitochondria isolated from treated roots was almost unaffected, showing just a slight decrease in oxygen consumption after treatment at pH 5.0. Similar results were obtained by treating the pea roots with another organic acid with a short carbon chain, that is, butyric acid. Based on these results, we propose a model in which HxA, in its undissociated form prevalent at acidic pH, stimulates the efflux of citrate, malate and NSC, which would, in turn, cause starvation of mitochondrial respiratory substrates of the Krebs cycle and a consequent decline in O2 consumption. Cation extrusion would be a compensatory mechanism in order to restore plasma membrane potential

Effects of periodontal therapy on white blood cell count and levels of transforming growth factor beta in serum of subjects with severe periodontitis

This study aimed to investigate the effects of nonsurgical periodontal therapy on white blood cell (WBC) count and levels of transforming growth factor beta (TGF—β) in serum from subjects with severe periodontitis. Serum from 28 subjects with periodontitis (mean age: 34.36±6.24; 32% men) and 27 healthy controls (mean age: 33.18±6.42; 33% men) were collected prior to therapy. Blood samples were obtained from 23 subjects who completed therapy (9—12 months). A well—controlled periodontal treatment protocol was established in three stages: mechanical periodontal therapy (scaling and root planning), reinstrumentation of dental sites, and supportive periodontal therapy. Periodontal and systemic parameters such as the total number of WBCs and TGF—β levels, accessed by enzyme—linked immunosorbent assay (ELISA), were included. After therapy, all clinical periodontal parameters decreased (

Acute tryptophan depletion Moja-De: a method to study central nervous serotonin function in children and adolescents

Serotonin (5-HT) is widely implicated as a key neurotransmitter relevant to a range of psychiatric disorders and psychological processes. The role of central nervous 5-HT function underlying these processes can be examined through serotonergic challenge methodologies. Acute tryptophan depletion (ATD) is a key challenge method whereby a diminished dietary intake of tryptophan—the amino acid precursor to brain 5-HT synthesis—results in temporary diminished central nervous 5-HT synthesis. While this particular methodology has been used in adult populations, it was only recently that modifications were made to enable the use of ATD in child and adolescent populations. Additionally, the Moja-De modification of the ATD challenge methodology has demonstrated benefits over other ATD techniques used previously. The aim of this protocol paper is to describe the ATD Moja-De methodology in detail, its benefits, as well as studies that have been conducted to validate the procedure in child and adolescent samples. The ATD Moja-De protocol provides a potential methodology for investigating the role of central nervous 5-HT via manipulation of brain tryptophan availability in human psychopathology from a developmental viewpoint

Low drug levels and thrombotic complications in high-risk atrial fibrillation patients treated with direct oral anticoagulants

Essentials Direct oral anticoagulants (DOACs) do not require laboratory monitoring currently. DOAC specific measurements were performed at trough in patients with atrial fibrillation. Patients who developed thromboembolic events showed lower DOAC plasma levels. This study supports the concept of measuring DOAC levels at steady state. Summary: Background Direct oral anticoagulants (DOACs) are administered at fixed doses without the need for dose adjustment according to laboratory testing. High interindividual variability in drug blood levels has been shown with all DOACs. To evaluate a possible relationship between DOAC C-trough anticoagulant levels and thromboembolic events, 565 consecutive naive patients with atrial fibrillation (AF) were enrolled in this study performed within the START Laboratory Registry. Methods DOAC-specific measurements (diluted thrombin time or anti-activated factor II calibrated for dabigatran; anti-activated FX calibrated for rivaroxaban or apixaban) at C-trough were performed locally at steady state within 15–25 days after the start of treatment. For each DOAC, the interval of C-trough levels, from the limit of quantification to the highest value, was subdivided into four equal classes, and results were attributed to these classes; the median values of results were also calculated. Thromboembolic complications occurring during 1 year of follow-up were recorded. Results Thromboembolic events (1.8%) occurred in 10 patients who had baseline C-trough levels in the lowest class of drug levels. The incidence of thromboembolic events among patients with DOAC C-trough levels in the lowest level class was 2.4%, and that in the remaining groups was 0%. The patients with thrombotic complications also had a higher mean CHA2DS2-VASc score than that of the total patient population: 5.3 (95% confidence interval [CI] 4.3–6.3 versus 3.0 (95% CI 2.9–3.1). Conclusion In this study cohort, thrombotic complications occurred only in DOAC-treated AF patients who had very low C-trough levels, with a relatively high CHA2DS2-VASc score. Larger studies are warranted to confirm these preliminary observations. © 2018 The Authors. Journal of Thrombosis and Haemostasis published by Wiley Periodicals, Inc. on behalf of International Society on Thrombosis and Haemostasis

Lupus anticoagulant in patients without thrombotic or obstetric complications

El inhibidor lúpico (IL) es un criterio de laboratorio para síndrome antifosfolipídico (SAF); sin embargo, puede detectarse en individuos asintomáticos o estar asociado a otras situaciones clínicas. Presentamos un análisis retrospectivo de 2000 exámenes consecutivos para IL (TTPA, DRVVT), de los cuales 499 casos no presentaban criterios clínicos de SAF (trombosis o complicaciones obstétricas). Aplicando los criterios SSC-ISTH, hallamos IL+ en 27,3% (410/1501) y 43,3% (216/499) de los casos con y sin clínica de SAF respectivamente, analizándose en los casos no-SAF las características clínicas y de laboratorio. Contexto clínico de casos IL+ no-SAF: 18,0% asintomáticos, 34,3% sangrado (epistaxis, gingivorragia, equimosis, hematomas espontáneos) y 47,7% otras manifestaciones (infertilidad, insuficiencia renal crónica, desórdenes autoinmunes, cardiopatía isquémica, trombocitopenia inmune, entre otras). Otras alteraciones de laboratorio en casos IL+ no- SAF, con síntomas de sangrado: alteraciones plaquetarias, descenso de VWF:RCo y/o VWF:Ag, disthrombocytopeminución de FVIII, FII, FV, FVII, FXI o fibrinógeno (sólo o sumado a disminución de plaquetas o FX), inhibidor a-FV o hiperfibrinolisis fueron detectadas en el 55,4% de los casos. El análisis mostró IL+ en un número importante de estudios (216/2000) sin criterios de SAF (1,95% en individuos asintomáticos, 3,70% en pacientes con síntomas de sangrado y 5,15% en casos con otro contexto clínico). Los casos con IL+ y sangrado representan un desafío particular, al requerir evaluar otros posibles defectos subyacentes, que pudiesen justificar el comportamiento clínico. La detección e identificación de defectos combinados requiere de un análisis minucioso, a fin de alcanzar un diagnóstico correcto, esencial para tomar decisiones terapéuticas adecuadas.Despite lupus anticoagulant (LA) is a laboratory criterion for antiphospholipid syndrome (APS), it can be present in asymptomatic subjects or it can be associated with other clinical settings. We present a retrospective analysis of 2000 consecutive LA assays (APTT, DRVVT), 499 of them were performed in patients without APS clinical criteria (thrombosis or obstetric complications). According to SSC-ISTH criteria, LA+ was found in 27.3% (410/1501) and 43.3% (216/499) of cases with or without APS criteria respectively; in no-APS group, the analysis of clinical background and laboratory features was done. Clinical background of LA+ cases no-APS: 18.0% asymptomatic, 34.3% bleeding symptoms (epistaxis, gingivorrhagia, bruising, spontaneous hematomas) and 47.7% other clinical settings (infertility, chronic kidney disease, autoimmune disorders, ischemic heart disease, idiopathic thrombocytopenic purpura, among others). Other abnormal laboratory tests in LA+ cases no- APS with bleeding symptoms: platelet dysfunction; low VWF:RCo and/or VWF:Ag; decrease of FVIII, FII, FV, FVII, FXI or fibrinogen (alone or with low platelet count or low FX), a-FV inhibitor and hyperfibrinolysis were found in the 55.4% of the cases. The analysis showed LA+ in an important number of cases (216/2000) without APS criteria (1.95% in asymptomatic cases, 3.70% in patients with bleeding symptoms and 5.15% in cases with other clinical settings). Those LA+ cases with bleeding symptoms represent a particular challenge because other possible underlying defects have to be analysed in order to explain the clinical behaviour. The detection and identifications of combined defects required a careful analysis in order to achieve an accurate diagnosis, essential for therapeutic decisions.Fil: Remotti, L.. Academia Nacional de Medicina de Buenos Aires. Instituto de Investigaciones Hematológicas ; ArgentinaFil: Grosso, S. H.. Academia Nacional de Medicina de Buenos Aires. Instituto de Investigaciones Hematológicas ; ArgentinaFil: Ingratti, M. F.. Academia Nacional de Medicina de Buenos Aires. Instituto de Investigaciones Hematológicas ; ArgentinaFil: Vera Morandini, Maria Paula. Academia Nacional de Medicina de Buenos Aires. Instituto de Investigaciones Hematológicas ; ArgentinaFil: Woods, Adriana Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Bermejo, E. I.. Academia Nacional de Medicina de Buenos Aires. Instituto de Investigaciones Hematológicas ; ArgentinaFil: Sánchez Luceros, Analía Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; Argentina. Academia Nacional de Medicina de Buenos Aires. Instituto de Investigaciones Hematológicas ; ArgentinaFil: Meschengieser, S. S.. Academia Nacional de Medicina de Buenos Aires. Instituto de Investigaciones Hematológicas ; ArgentinaFil: Lazzari, María Ángela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Blanco, A. N.. Academia Nacional de Medicina de Buenos Aires. Instituto de Investigaciones Hematológicas ; Argentin

Archaeology and Archaeometry of a local production of Black Glazed Ware at Pompeii

International audienceThe paper focuses on a local production of Black Glazed ware attested in Pompeii between the mid-fourth and the early-third century B.C. The ceramics thereafter presented were found in a specific archaeological deposit termed as X B11, brought to light in stratigraphic excavations undertaken in the forum area in 1980/81 by P. Arthur on behalf of the local Superintendence