scholarly journals Polymer coil-globule phase transition is a universal folding principle of Drosophila epigenetic domains

2018 ◽  
Author(s):  
Antony Lesage ◽  
Vincent Dahirel ◽  
Jean-Marc Victor ◽  
Maria Barbi
Keyword(s):  
Scaling Laws ◽  
Persistence Length ◽  
Finite Size ◽  
Super Resolution ◽  
Structural Features ◽  
Polymer Physics ◽  
The Mean ◽  
Induced Changes ◽  
First Time

AbstractBackgroundLocalized functional domains within chromosomes, known as topologically associating domains (TADs), have been recently highlighted. In Drosophila, TADs are biochemically defined by epigenetic marks, this suggesting that the 3D arrangement may be the “missing link” between epigenetics and gene activity. Recent observations (Boettiger et al., Nature 2016) provide access to structural features of these domains with unprecedented resolution thanks to super-resolution experiments. In particular, they give access to the distribution of the radii of gyration for domains of different linear length and associated with different transcriptional activity states: active, inactive or repressed. Intriguingly, the observed scaling laws lack consistent interpretation in polymer physics.ResultsWe develop a new methodology conceived to extract the best information from such super-resolution data by exploiting the whole distribution of gyration radii, and to place these experimental results on a theoretical framework. We show that the experimental data are compatible with the finite-size behavior of a self-attracting polymer. The same generic polymer model leads to quantitative differences between active, inactive and repressed domains. Active domains behave as pure polymer coils, while inactive and repressed domains both lie at the coil-globule crossover. For the first time, the “colo-specificity” of both the persistence length and the mean interaction energy are estimated, leading to important differences between epigenetic states.ConclusionsThese results point toward a crucial role of criticality to enhance the system responsivity, resulting in both energy transitions and structural rearrangements. We get strong indications that epigenetically induced changes in nucleosome-nucleosome interaction can cause chromatin to shift between different activity states.

scholarly journals The Role of Fine Needle Aspiration of Orbital Lesions: A Case Series

2016 ◽  
Vol 60 (1) ◽  
pp. 31-38 ◽  
Author(s):  
Fabio Pagni ◽  
Marta Jaconi ◽  
Andrew James Smith ◽  
Ambrogio Brenna ◽  
Maria Gabriella Valente ◽  
...  
Keyword(s):  
Case Series ◽  
Needle Aspiration ◽  
Lesion Size ◽  
Fine Needle ◽  
Computed Tomography Scans ◽  
The Mean ◽  
The Right ◽  
First Time ◽  
Orbital Lesions

Objective: This paper analyzes a series of ultrasound (US)-guided orbital fine needle aspirations (FNAs) which provide diagnostic information that cytopathologists approaching orbital lesions for the first time can find useful and underlines the importance of teamwork. Study Design: The investigators retrospectively obtained data from 24 consecutive orbital FNAs. For all patients, a complete clinicoradiological database was created. FNAs were performed under US guidance with 25-gauge needles and an aspiration biopsy syringe gun, and sent to the Department of Pathology for examination and data management. Results: The mean age of the patients was 54 years. Imaging studies included US, magnetic resonance imaging and computed tomography scans; 9 lesions involved the right orbit and 15 the left orbit. The mean lesion size was 23.6 ± 7.2 mm. After microscopic examination, 7 smears were labeled as ‘nondiagnostic', while in 17 cases a definitive diagnosis was proposed, which always proved to be correct (70.8%, specificity = 100%). Conclusions: The investigators believe that FNA biopsy of orbital masses is a necessary step; its weaknesses lie in the particularly delicate site of sampling and the extreme heterogeneity of lesions. Nevertheless, when orbital FNA is performed within a well-coordinated multidisciplinary team, it is a powerful tool that can be used to define the most appropriate management of these patients.

Aminophosphonate-Induced Changes of Betacyanine and Ionic Efflux

2001 ◽  
Vol 56 (5-6) ◽  
pp. 349-352 ◽  
Author(s):  
Edward Grzyś ◽  
Krzysztof Bielecki ◽  
Janusz Sarapuk
Keyword(s):  
Beta Vulgaris ◽  
Cell Membranes ◽  
Structural Features ◽  
Red Beet ◽  
Induced Changes

Betacyanine and ionic leakage from red beet (Beta vulgaris ssp. L. rapacea) roots and lilac (Syringa vulgaris L.) leaves under the influence of new aminophosphonates were studied by spectroscopic and conductometric methods. It was found that the leakage of dye or electrolytes depended both on the concentration of the compounds used and their structural features. The results compared to those obtained for the well known herbicide Buminafos® (dibutyl 1-butylamino-1-cyclohexanephosphonate) enabled to conclude that some of the compounds studied exhibited comparable or better activity than this herbicide. That makes them potentially good herbicides. It is possible that the effects observed are the result of action on cell membranes of the tissues used. The possible role of the structural features of aminophosphonates in this action is discussed.

scholarly journals Impulse response function for Brownian motion

Soft Matter ◽  
2021 ◽  
Author(s):  
Nicos Makris
Keyword(s):  
Brownian Motion ◽  
Time Derivative ◽  
Mean Square Displacement ◽  
Impulse Response Function ◽  
Velocity Autocorrelation Function ◽  
Mean Square ◽  
Velocity Autocorrelation ◽  
The Mean ◽  
First Time

Motivated from the central role of the mean-square displacement and its second time-derivative – that is the velocity autocorrelation function in the description of Brownian motion, we revisit the physical meaning of its first time-derivative.

scholarly journals The role of galaxies and AGN in reionizing the IGM – III. IGM–galaxy cross-correlations at z ∼ 6 from eight quasar fields with DEIMOS and MUSE

2020 ◽  
Vol 494 (2) ◽  
pp. 1560-1578
Author(s):  
Romain A Meyer ◽  
Koki Kakiichi ◽  
Sarah E I Bosman ◽  
Richard S Ellis ◽  
Nicolas Laporte ◽  
...  
Keyword(s):  
Correlation Function ◽  
Cross Correlation ◽  
Mean Free Path ◽  
Lyman Break Galaxies ◽  
The Galaxy ◽  
Cross Correlations ◽  
The Mean ◽  
Improved Model ◽  
First Time

ABSTRACT We present improved results of the measurement of the correlation between galaxies and the intergalactic medium transmission at the end of reionization. We have gathered a sample of 13 spectroscopically confirmed Lyman-break galaxies (LBGs) and 21 Lyman-α emitters (LAEs) at angular separations 20 arcsec ≲ θ ≲ 10 arcmin (∼0.1–4 pMpc at z ∼ 6) from the sightlines to eight background z ≳ 6 quasars. We report for the first time the detection of an excess of Lyman-α transmission spikes at ∼10–60 cMpc from LAEs (3.2σ) and LBGs (1.9σ). We interpret the data with an improved model of the galaxy–Lyman-α transmission and two-point cross-correlations, which includes the enhanced photoionization due to clustered faint sources, enhanced gas densities around the central bright objects and spatial variations of the mean free path. The observed LAE(LBG)–Lyman-α transmission spike two-point cross-correlation function (2PCCF) constrains the luminosity-averaged escape fraction of all galaxies contributing to reionization to $\langle f_{\rm esc} \rangle _{M_{\rm UV}\lt -12} = 0.14_{-0.05}^{+0.28}\, (0.23_{-0.12}^{+0.46})$. We investigate if the 2PCCF measurement can determine whether bright or faint galaxies are the dominant contributors to reionization. Our results show that a contribution from faint galaxies ($M_{\rm UV} \gt -20 \, (2\sigma)$) is necessary to reproduce the observed 2PCCF and that reionization might be driven by different sub-populations around LBGs and LAEs at z ∼ 6.

scholarly journals N- and O-glycosylation Analysis of Human C1-inhibitor Reveals Extensive Mucin-type O-Glycosylation

2017 ◽  
Vol 17 (6) ◽  
pp. 1225-1238 ◽  
Author(s):  
Kathrin Stavenhagen ◽  
H. Mehmet Kayili ◽  
Stephanie Holst ◽  
Carolien A. M. Koeleman ◽  
Ruchira Engel ◽  
...  
Keyword(s):  
Electron Transfer Dissociation ◽  
Structural Features ◽  
C1 Inhibitor ◽  
Contact Activation ◽  
Site Specific ◽  
Functional Studies ◽  
Glycosylation Sites ◽  
Pngase F ◽  
First Time

Human C1-inhibitor (C1-Inh) is a serine protease inhibitor and the major regulator of the contact activation pathway as well as the classical and lectin complement pathways. It is known to be a highly glycosylated plasma glycoprotein. However, both the structural features and biological role of C1-Inh glycosylation are largely unknown. Here, we performed for the first time an in-depth site-specific N- and O-glycosylation analysis of C1-Inh combining various mass spectrometric approaches, including C18-porous graphitized carbon (PGC)-LC-ESI-QTOF-MS/MS applying stepping-energy collision-induced dissociation (CID) and electron-transfer dissociation (ETD). Various proteases were applied, partly in combination with PNGase F and exoglycosidase treatment, in order to analyze the (glyco)peptides. The analysis revealed an extensively O-glycosylated N-terminal region. Five novel and five known O-glycosylation sites were identified, carrying mainly core1-type O-glycans. In addition, we detected a heavily O-glycosylated portion spanning from Thr82-Ser121 with up to 16 O-glycans attached. Likewise, all known six N-glycosylation sites were covered and confirmed by this site-specific glycosylation analysis. The glycoforms were in accordance with results on released N-glycans by MALDI-TOF/TOF-MS/MS. The comprehensive characterization of C1-Inh glycosylation described in this study will form the basis for further functional studies on the role of these glycan modifications.

scholarly journals How Sample Paths of Leaky Integrate-and-Fire Models Are Influenced by the Presence of a Firing Threshold

2011 ◽  
Vol 23 (7) ◽  
pp. 1743-1767 ◽  
Author(s):  
Maria Teresa Giraudo ◽  
Priscilla E. Greenwood ◽  
Laura Sacerdote
Keyword(s):  
Membrane Potential ◽  
Diffusion Process ◽  
Fixed Time ◽  
Firing Time ◽  
Fire Model ◽  
Integrate And Fire ◽  
Sample Paths ◽  
The Mean ◽  
First Time

Neural membrane potential data are necessarily conditional on observation being prior to a firing time. In a stochastic leaky integrate-and-fire model, this corresponds to conditioning the process on not crossing a boundary. In the literature, simulation and estimation have almost always been done using unconditioned processes. In this letter, we determine the stochastic differential equations of a diffusion process conditioned to stay below a level S up to a fixed time t1 and of a diffusion process conditioned to cross the boundary for the first time at t1. This allows simulation of sample paths and identification of the corresponding mean process. Differences between the mean of free and conditioned processes are illustrated, as well as the role of noise in increasing these differences.

scholarly journals The role of paediatricians in the prophylaxis of early childhood caries

2018 ◽  
Vol 31 (3) ◽  
pp. 154-156
Author(s):  
Kamila Fux-Zalewska ◽  
Beata Kubic-Filiks ◽  
Jolanta Szymanska
Keyword(s):  
Early Childhood ◽  
Early Childhood Caries ◽  
Deciduous Tooth ◽  
Comprehensive Care ◽  
Nursery Schools ◽  
Developmental Age ◽  
The Mean ◽  
First Time ◽  
Childhood Caries

Abstract The first visit to the dentist should take place within 6 months after the first deciduous tooth erupts, and not later than in the 12th month of the child’s life. To assess the role of paediatricians in the prophylaxis of early childhood caries, the authors studied recommendations given to parents about the age when their child should see the dentist for the first time. The survey covered 250 parents of children aged from 11 to 69 months who attended nursery schools and kindergartens in Lublin. Our results show that paediatricians only referred 12.80% (n = 32) of all children at the age of between 3 to 66 months for their first visit to the dentist. Herein, half of the references were of children younger than 2 years (Me = 24.0). In total, the mean age of the child was 22.41 ± 13.24 months on reference. Thus, paediatricians refer children to the dentist for their first visit too seldom and too late. It is essential that paediatricians learn to participate to a greater extent in the prevention of early childhood caries. The cooperation between the paediatrician and the dentist is necessary to provide complex and comprehensive care to developmental age patients.

scholarly journals Oral and pre-absorptive sensing of amino acids relates to hypothalamic control of food intake in rainbow trout

2020 ◽  
Vol 223 (17) ◽  
pp. jeb221721
Author(s):  
Sara Comesaña ◽  
Marta Conde-Sieira ◽  
Cristina Velasco ◽  
José L. Soengas ◽  
Sofia Morais
Keyword(s):  
Amino Acids ◽  
Rainbow Trout ◽  
Food Intake ◽  
Oral Administration ◽  
Glutamic Acid ◽  
Oral Treatment ◽  
Taste Receptor ◽  
Induced Changes ◽  
First Time

ABSTRACTTo assess the putative role of taste and pre-absorptive sensing of amino acids in food intake control in fish, we carried out an oral administration with l-leucine, l-valine, l-proline or l-glutamic acid in rainbow trout (Oncorhynchus mykiss). Treatment with proline significantly reduced voluntary food intake at 2 h and 3 h after oral administration, while glutamic acid showed a less pronounced satiating effect at 3 h. The mRNA expression of taste receptor subunits tas1r1, tas1r2a, tas1r2b and tas1r3 was measured in the epithelium overlying the bony basihyal of the fish (analogous to the tetrapod tongue) at 10, 20 or 30 min following treatment. No significant changes were observed, except for a tas1r down-regulation by valine at 30 min. Of the downstream taste signalling genes that were analysed in parallel, plcb2 and possibly trpm5 (non-significant trend) were down-regulated 20 min after proline and glutamic acid treatment. The signal originated in the oropharyngeal and/or gastric cavity presumably relays to the brain as changes in genes involved in the regulation of food intake occurred in hypothalamus 10–30 min after oral treatment with amino acids. In particular, proline induced changes consistent with an increased anorexigenic potential in the hypothalamus. We have therefore demonstrated, for the first time in fish, that the peripheral (pre-absorptive) detection of an amino acid (l-proline), presumably by taste-related mechanisms, elicits a satiety signal that in hypothalamus is translated into changes in cellular signalling and neuropeptides regulating food intake, ultimately resulting in decreased food intake.

Digital x-ray mapping of nanometer-size supported bimetallic catalysts

1988 ◽  
Vol 46 ◽  
pp. 530-531
Author(s):  
L. T. Germinario
Keyword(s):  
Background Radiation ◽  
Metal Cluster ◽  
Single Element ◽  
Beam Diameter ◽  
X Rays ◽  
X Ray ◽  
Major Interest ◽  
Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

Psychological Resilience Provides No Independent Protection From Suicidal Risk

Crisis ◽  
2016 ◽  
Vol 37 (2) ◽  
pp. 130-139 ◽  
Author(s):  
Danica W. Y. Liu ◽  
A. Kate Fairweather-Schmidt ◽  
Richard Burns ◽  
Rachel M. Roberts ◽  
Kaarin J. Anstey
Keyword(s):  
Risk Factors ◽  
Well Being ◽  
Current Status ◽  
Psychological Resilience ◽  
Cross Sectional ◽  
Life Project ◽  
Resilience Factors ◽  
First Time

Abstract. Background: Little is known about the role of resilience in the likelihood of suicidal ideation (SI) over time. Aims: We examined the association between resilience and SI in a young-adult cohort over 4 years. Our objectives were to determine whether resilience was associated with SI at follow-up or, conversely, whether SI was associated with lowered resilience at follow-up. Method: Participants were selected from the Personality and Total Health (PATH) Through Life Project from Canberra and Queanbeyan, Australia, aged 28–32 years at the first time point and 32–36 at the second. Multinomial, linear, and binary regression analyses explored the association between resilience and SI over two time points. Models were adjusted for suicidality risk factors. Results: While unadjusted analyses identified associations between resilience and SI, these effects were fully explained by the inclusion of other suicidality risk factors. Conclusion: Despite strong cross-sectional associations, resilience and SI appear to be unrelated in a longitudinal context, once risk/resilience factors are controlled for. As independent indicators of psychological well-being, suicidality and resilience are essential if current status is to be captured. However, the addition of other factors (e.g., support, mastery) makes this association tenuous. Consequently, resilience per se may not be protective of SI.

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