Chromosome Centromeres: Structural and Analytical Investigations with High Resolution Scanning Electron Microscopy in Combination with Focused Ion Beam Milling

Whole mount mitotic metaphase chromosomes of different plants and animals were investigated with high resolution field emission scanning electron microscopy (FESEM) to study the ultrastructural organization of centromeres, including metacentric, acrocentric, telocentric, and holocentric chromosome variants. It could be shown that, in general, primary constrictions have distinctive ultrastructural features characterized by parallel matrix fibrils and fewer smaller chromomeres. Exposure of these structures depends on cell cycle synchronization prior to chromosome isolation, chromosome size, and chromosome isolation technique. Chromosomes without primary constrictions, small chromosomes, and holocentric chromosomes do not exhibit distinct ultrastructural elements that could be directly correlated to centromere function. Putative spindle structures, although rarely observed, spread over the primary constriction to the bordering pericentric regions. Analytical FESEM techniques, including specific DNA staining with Pt blue, staining of protein as a substance class with silver-colloid, and artificial loosening of fixed chromosomes with proteinase K, were applied, showing that centromere variants and ultrastructural elements in the centromere differ in DNA and protein distribution. Immunogold localization allowed high-resolution comparison between chromosomes with different centromere orientations of the distribution of centromere-related histone variants, phosphorylated histone H3 (ser10), and CENH3. A novel application of FESEM combined with focused ion beam milling (FIB) provided new insights into the spatial distribution of these histone variants in barley chromosomes. Copyright (C) 2009 S. Karger AG, Base

Alternative final steps in berberine biosynthesis in Coptis japonica cell cultures

In Coptis japonica cell cultures an alternative pathway has been discovered which leads from (S)-tetrahydrocolumbamine via (S)-canadine to berberine. The two enzymes involved have been partially purified. (S)-Tetrahydrocolumbamine is stereospecifically transformed into (S)-canadine under formation of the methylenedioxy bridge in ring A. This new enzyme was named (S)-canadine synthase. (S)-Canadine in turn is stereospecifically dehydrogenated to berberine by an oxidase, (S)-canadine oxidase (COX), which was partially purified (25-fold). This enzyme has many physical properties in common with the already known (S)-tetrahydroprotoberberine oxidase from Berberis but grossly differs from the latter enzyme in its cofactor requirement (Fe) and its substrate specificity. Neither (S)-norreticuline nor (S)-scoulerine serves as substrate for the Coptis enzyme, while both substrates are readily oxidized by the Berberis enzyme. The four terminal enzymes catalyzing the pathway from (S)-reticuline to berberine are housed in Berberis as well as in Coptis in smooth vesicles with a density of =1.14 g/ml. These vesicles have been enriched and characterized by electron microscopy

NEUROIMÁGENES EN ENFERMEDAD DE PARKINSON: ROL DE LA RESONANCIA MAGNÉTICA, EL SPECT Y EL PET

RESUMENLa enfermedad de Parkinson (EP) es un trastorno neurodegenerativo, caracterizado por la pérdida progresiva de neuronas monoaminérgicas, en especial dopaminérgicas. En las últimas décadas, se han desarrollado diversos biomarcadores para el estudio de los pacientes con EP. Un grupo de estos biomarcadores son las neuroimágenes, como la resonancia magnética cerebral y las imágenes moleculares, en particular, la tomografía por emisión de positrones (PET) y la tomografía por emisión de fotón único (SPECT). Estas técnicas, se han empleado en el diagnóstico temprano de la EP, así como para mejorar el diagnóstico diferencial entre EP y otros parkinsonismos y para monitorizar la progresión de la enfermedad. Con estos fines, se ha utilizado la capacidad de estas técnicas para evaluar la pérdida de la actividad dopaminérgica y de otras vías monoaminérgicas, al igual que la posibilidad de valorar la inflamación y el metabolismo a nivel cerebral. Recientemente, los nuevos criterios para el diagnóstico de la EP reconocen al PET y SPECT como herramientas valiosas en el diagnóstico de esta enfermedad. En este artículo, se analiza la utilidad actual de las técnicas de imagen en pacientes con EP y otros parkinsonismos y sus potenciales aplicaciones futuras.SUMMARYParkinson's disease (PD) is a neurodegenerative disorder characterized by a progressive loss of monoaminergic neurons, particularly dopaminergic cell groups. Biomarkers have been developed in the last decades for the study of PD patients. Neuroimages, including Magnetic Resonance Imaging (MRI), Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography are part of these biomarkers evaluated in PD. These techniques had been used for the early diagnosis of PD, for the differential diagnosis between PD and other parkinsonisms and to monitor the progression of these disorders. The ability of these images to evaluate loss of monoaminergic activity and their capacity to estimate inflammatory and metabolic changes in the brain has been used. Recently the new criteria for diagnosis of PD have incorporated to PET and SPECT as useful tools in the diagnosis of this disorder. In this article, we review the utility of the neuroimages in patients with PD and some of their potential future applications

Wet season Mediterranean precipitation variability: influence of large-scale dynamics and trends

Abstract : The influence of the large-scale atmospheric circulation at several tropospheric levels on wet season precipitation over 292 sites across the Mediterranean area is assessed. A statistical downscaling model is designed with an objective methodology based on empirical orthogonal functions and canonical correlation analysis (CCA) and tested by means of cross-validation. In all 30% of the total Mediterranean October to March precipitation variability can be accounted for by the combination of four large-scale geopotential height fields and sea level pressure. The Mediterranean sea surface temperatures seem to be less relevant to explain precipitation variability at interannual time scale. It is shown that interdecadal changes in the first CCA mode are related to variations in the North Atlantic Oscillation index and responsible for comparable time scale variations of the Mediterranean precipitation throughout the twentieth century. The analysis reveals that since the mid-nineteenth century precipitation steadily increased with a maximum in the 1960s and decreased since then. The second half of the twentieth century shows a general downward trend of 2.2mm·month-1·decade-

La pratique des jeux de hasard et d’argent, les comportements délinquants et la consommation problématique de substances psychotropes : une perspective développementale

Cette étude comporte deux objectifs : 1) vérifier si les liens entre la pratique problématique des jeux de hasard et d’argent, les comportements délinquants et les problèmes de consommation de substances psychotropes diminuent au début de l’âge adulte par rapport au milieu de l’adolescence, et 2) vérifier si les liens entre ces trois ordres de comportements problématiques au début de l’âge adulte sont, en partie ou en totalité, attribuables à des antécédents communs. Deux échantillons populationnels de répondants de sexe masculin ont été mis à contribution afin de vérifier ces objectifs. Les mesures recueillies à 12 ans (i.e. les présumés antécédents communs) couvrent des aspects liés aux caractéristiques personnelles, familiales et sociales des participants. Celles recueillies à 16 et 23 ans se rapportent à leurs habitudes de jeu, à leurs comportements délinquants et à leur consommation de substances psychotropes. Ces dernières sont autorévélées alors que les précédentes font appel à des sources variées d’évaluation. Les résultats révèlent que les liens entre la pratique des jeux de hasard et d’argent, les comportements délinquants et la consommation de psychotropes au début de l’âge adulte (23 ans) sont similaires aux liens qui existent déjà à 16 ans. Ces liens ne peuvent toutefois pas être attribuables aux antécédents communs mesurés à la préadolescence (12 ans). La discussion explore les retombées pratiques et théoriques de ces résultats.This study addressed two questions: 1) Are the concurrent links between gambling, delinquency and drug use weaker during early adulthood than during middle adolescence; 2) Can the concurrent links by early adulthood be explained, at least in part, by common antecedent factors? Two population based samples of males were used to answer these questions. The putative common antecedent factors were assessed when the participants were 12 years old. These factors include variables from three domains of functioning: self, family and peers. Gambling, delinquency and drug use were assessed at age 16 years and again at age 23. Results show that the links between gambling, delinquency and drug use are not weaker by early adulthood (i.e. age 23) than they were by middle adolescence (i.e. age 16). In addition, these links cannot be explained by the age 12 antecedent factors. The discussion stresses the theoretical and applied implications of these findings

Telehealth Benefits in Rural Areas: Occupational Therapy

This paper focuses on the efficacy of occupational-based interventions administered via telehealth within a rural-dwelling adult (18 years and older) population with mental health conditions. The main factors to consider in this scenario are the mental health services in rural areas, the features of the rural population, and the role of occupational therapy (OT) and telehealth in rural mental health. The Occupational Therapy Practice Framework defined health management as “activities related to developing, managing, and maintaining health and wellness routines, including self-management, with the goal of improving or maintaining health to support participation and other occupation” (AOTA, 2020, p.32)

Effect of Glacial/Interglacial Recharge Conditions on Flow of Meteoric Water Through Deep Orogenic Faults: Insights Into the Geothermal System at Grimsel Pass, Switzerland

Many meteoric-recharged, fault-hosted geothermal systems in amagmatic orogenic belts have been active through the Pleistocene glacial/interglacial climate fluctuations. The effects of climate-induced recharge variations on fluid flow patterns and residence times of the thermal waters are complex and may influence how the geothermal and mineralization potential of the systems are evaluated. We report systematic thermal-hydraulic simulations designed to reveal the effects of recharge variations, using a model patterned on the orogenic geothermal system at Grimsel Pass in the Swiss Alps. Previous studies have shown that fault-bounded circulation of meteoric water is driven to depths of ∼10 km by the high alpine topography. Simulations suggest that the current single-pass flow is typical of interglacial periods, during which (a) meteoric recharge into the fault is high (above tens of centimeters per year), (b) conditions are at or somewhat below the critical Rayleigh number, and (c) hydraulic connectivity along the fault plane is extensive (an extent of at least 10 km into increasingly higher terrain is required to explain the 10 km penetration depth). The subcritical condition constrains the bulk fault permeability to <1e-14 m2. In contrast, the limited recharge during the numerous Pleistocene glaciation events likely induced a layered flow system, with single-pass flow confined to shallow depths while non-Rayleigh convection occurred deeper in the fault. The same layering can be observed at low aspect ratios (length/depth) of the fault plane, when the available recharge area limits flux through the fault

Subtraction of test mass angular noise in the LISA Technology Package interferometer

We present recent sensitivity measurements of the LISA Technology Package interferometer with articulated mirrors as test masses, actuated by piezo-electric transducers. The required longitudinal displacement resolution of 9 pm/sqrt[Hz] above 3 mHz has been demonstrated with an angular noise that corresponds to the expected in on-orbit operation. The excess noise contribution of this test mass jitter onto the sensitive displacement readout was completely subtracted by fitting the angular interferometric data streams to the longitudinal displacement measurement. Thus, this cross-coupling constitutes no limitation to the required performance of the LISA Technology Package interferometry.Comment: Applied Physics B - Lasers and Optics (2008