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https://www.readbyqxmd.com/read/30540436/chemistry-of-shape-controlled-iron-oxide-nanocrystal-formation
#1
Artur Feld, Agnes Weimer, Andreas Kornowski, Naomi Winckelmans, Jan-Philip Merkl, Hauke Kloust, Robert Zierold, Christian Schmidtke, Theo Schotten, Maria Riedner, Sara Bals, Horst Weller Prof Dr
Herein we demonstrate that meticulous and in-depth analysis of the reaction mechanisms of nanoparticle formation is rewarded by full control of size, shape and crystal structure of superparamagnetic iron oxide nanocrystals during synthesis. Starting from two iron sources - iron(II)- and iron(III) carbonate -a strict separation of oleate formation from the generation of reactive pyrolysis products and concomitant nucleation of iron oxide nanoparticles was achieved. This protocol enabled us to analyze each step of nanoparticle formation independently in depth...
December 12, 2018: ACS Nano
https://www.readbyqxmd.com/read/30481489/myoglianin-triggers-the-pre-metamorphosis-stage-in-hemimetabolan-insects
#2
Orathai Kamsoi, Xavier Belles
Insect metamorphosis is triggered by a decrease in juvenile hormone (JH) in the final juvenile instar. What induces this decrease is therefore a relevant question. Working with the cockroach Blattella germanica, we found that myoglianin (Myo), a ligand in the TGF-β signaling pathway, is highly expressed in the corpora allata (CA, the JH-producing glands) and the prothoracic gland [(PG), which produce ecdysone] during the penultimate (fifth) nymphal instar (N5). In the CA, high Myo levels during N5 repress the expression of juvenile hormone acid methyl transferase, a JH biosynthesis gene...
November 27, 2018: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
https://www.readbyqxmd.com/read/30468871/small-scale-culture-of-plasmodium-falciparum-using-%C3%AE-slide-angiogenesis-followed-by-automatic-infection-rate-counting-to-assess-drug-effects
#3
Muneaki Hashimoto, Yusuke Ido, Masato Tanaka, Kazumichi Yokota, Kazuaki Kajimoto, Masatoshi Kataoka
It is very important to reduce the costs involved in malarial drug development by small-scale culture of Plasmodium falciparum, and automation of the assay system for drug efficacy against the parasites for high-throughput screening. In this study, we report that P. falciparum-infected erythrocytes can be stably cultured on μ-Slide Angiogenesis, which is used to investigate angiogenesis in tube formation assays, followed by automatic counting of the infection rate (parasitaemia). After 10 μL of parasite-infected erythrocytes were added to the inner well of μ-Slide Angiogenesis to prevent a multilayer of erythrocytes, 30 μL of silicon oil was overlaid on the culture medium to avoid evaporation of the medium, leading to stable small-scale parasite cultivation...
November 20, 2018: Parasitology International
https://www.readbyqxmd.com/read/30464840/thyroid-hormone-levels-and-temperature-during-development-alter-thermal-tolerance-and-energetics-of-xenopus-laevis-larvae
#4
Katharina Ruthsatz, Kathrin H Dausmann, Myron A Peck, Claudia Drees, Nikita M Sabatino, Laura I Becker, Janica Reese, Lisa Hartmann, Julian Glos
Environmental variation induced by natural and anthropogenic processes including climate change may threaten species by causing environmental stress. Anuran larvae experiencing environmental stress may display altered thyroid hormone (TH) status with potential implications for physiological traits. Therefore, any capacity to adapt to environmental changes through plastic responses provides a key to determining species vulnerability to environmental variation. We investigated whether developmental temperature ( T dev ), altered TH levels and whether the interactive effect of both affect standard metabolic rate (SMR), body condition (BC), survival and thermal tolerance in larvae of the African clawed frog ( Xenopus laevis ) reared at five temperatures with experimentally altered TH levels...
2018: Conservation Physiology
https://www.readbyqxmd.com/read/30460917/age-and-size-dependent-resistance-to-chytridiomycosis-in-the-invasive-cane-toad-rhinella-marina
#5
Laura A Brannelly, Gerardo Martin, John Llewelyn, Lee F Skerratt, Lee Berger
In Australia, the cane toad Rhinella marina and chytrid fungus Batrachochytrium dendrobatidis (Bd) are examples of invasive species that have had dramatic impacts on native fauna. However, little is known about the interaction between Bd and cane toads. We aimed to explore the interaction of these 2 species in 3 parts. First, we collated data from the literature on Bd infection in wild cane toads. Second, we tested the susceptibility of recently metamorphosed cane toads to Bd infection. Finally, we modelled the distribution of the 2 species in Australia to identify where they overlap and, therefore, might interact...
November 6, 2018: Diseases of Aquatic Organisms
https://www.readbyqxmd.com/read/30456781/how-thyroid-hormones-and-their-inhibitors-affect-cartilage-growth-and-shape-in-the-frog-xenopus-laevis
#6
Christopher S Rose, Jennifer W Cahill
Understanding how skeleton changes shape in ontogeny is fundamental to understanding how its shape diversifies in phylogeny. Amphibians pose a special case because their jaw and throat skeleton consists of cartilages that are dramatically reshaped midway through life to support new feeding and breathing styles. Although amphibian metamorphosis is commonly studied by immersing larvae in thyroid hormones (TH), how individual cartilages respond to TH is poorly understood. This study documents the effects of larval stage and TH type (T4 vs...
November 20, 2018: Journal of Anatomy
https://www.readbyqxmd.com/read/30451887/high-pressure-metamorphism-caused-by-fluid-induced-weakening-of-deep-continental-crust
#7
Bjørn Jamtveit, Evangelos Moulas, Torgeir B Andersen, Håkon Austrheim, Fernando Corfu, Arianne Petley-Ragan, Stefan M Schmalholz
Studies of mineral equilibria in metamorphic rocks have given valuable insights into the tectonic processes operating at convergent plate margins during an orogeny. Geodynamic models simulating orogenesis and crustal thickening have been constrained by temperature and pressure estimates inferred from the mineral assemblages of the various lithologies involved along with age constrains from increasingly precise geochronological techniques. During such studies it is assumed that the pressure experienced by a given rock is uniquely related to its depth of burial...
November 19, 2018: Scientific Reports
https://www.readbyqxmd.com/read/30430240/expression-of-hyaluronan-synthases-upregulated-by-thyroid-hormone-is-involved-in-intestinal-stem-cell-development-during-xenopus-laevis-metamorphosis
#8
Kenta Fujimoto, Takashi Hasebe, Mitsuko Kajita, Atsuko Ishizuya-Oka
During amphibian intestinal remodeling, thyroid hormone (TH) induces adult stem cells, which newly generate the absorptive epithelium analogous to the mammalian one. We have previously shown that hyaluronan (HA) is newly synthesized and plays an essential role in the development of the stem cells via its major receptor CD44 in the Xenopus laevis intestine. We here focused on HA synthase (HAS) and examined how the expression of HAS family genes is regulated during natural and TH-induced metamorphosis. Our quantitative RT-PCR analysis indicated that the mRNA expression of HAS2 and HAS3, but not that of HAS1 and HAS-rs, a unique Xenopus HAS-related sequence, is upregulated concomitantly with the development of adult epithelial primordia consisting of the stem/progenitor cells during the metamorphic climax...
December 2018: Development Genes and Evolution
https://www.readbyqxmd.com/read/30428127/dynamic-molecular-metamorphism-involving-palladium-assisted-dimerization-of-%C3%AF-cation-radicals
#9
Christophe Kahlfuss, Raymond Grüber, Elise Dumont, Guy Royal, Floris Chevallier, Eric Saint-Aman, Christophe Bucher
A dynamic supramolecular approach is developed to promote the π-dimerization of viologen radicals at room temperature and in standard concentration ranges. It involves cis- or trans-protected palladium centers serving as inorganic hinges linking two functionalized viologens endowed with metal-ion coordinating properties. On the ground of detailed spectroscopic, electrochemical and computational data, we show that the one electron electrochemical reduction of the viologen units in different dynamic metal:ligand mixtures leads to the formation of the same intramolecular pi-dimer, regardless of the initial environment around the metallic precursor and of the relative ratio between metal and ligand initially introduced in solution...
November 14, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/30416201/the-accuracy-of-standard-enthalpies-and-entropies-for-phases-of-petrological-interest-derived-from-density-functional-calculations
#10
Artur Benisek, Edgar Dachs
The internal energies and entropies of 21 well-known minerals were calculated using the density functional theory (DFT), viz. kyanite, sillimanite, andalusite, albite, microcline, forsterite, fayalite, diopside, jadeite, hedenbergite, pyrope, grossular, talc, pyrophyllite, phlogopite, annite, muscovite, brucite, portlandite, tremolite, and CaTiO3 -perovskite. These thermodynamic quantities were then transformed into standard enthalpies of formation from the elements and standard entropies enabling a direct comparison with tabulated values...
2018: Contributions to Mineralogy and Petrology. Beiträge Zur Mineralogie und Petrologie
https://www.readbyqxmd.com/read/30373832/shear-heating-reconciles-thermal-models-with-the-metamorphic-rock-record-of-subduction
#11
Matthew J Kohn, Adrian E Castro, Buchanan C Kerswell, César R Ranero, Frank S Spear
Some commonly referenced thermal-mechanical models of current subduction zones imply temperatures that are 100-500 °C colder at 30-80-km depth than pressure-temperature conditions determined thermobarometrically from exhumed metamorphic rocks. Accurately inferring subduction zone thermal structure, whether from models or rocks, is crucial for predicting metamorphic reactions and associated fluid release, subarc melting conditions, rheologies, and fault-slip phenomena. Here, we compile surface heat flow data from subduction zones worldwide and show that values are higher than can be explained for a frictionless subduction interface often assumed for modeling...
November 13, 2018: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/30357736/central-hypoxia-elicits-long-term-expression-of-the-lung-motor-pattern-in-pre-metamorphic-lithobates-catesbeianus
#12
Tara A Janes, Richard Kinkead
During vertebrate development, the neural networks underlying air-breathing undergo changes in connectivity and functionality, allowing lung ventilation to emerge. Yet, the factors regulating development of these critical homeostatic networks remain unresolved. In amphibians, air-breathing occurs sporadically prior to metamorphosis. However, in tadpoles of Lithobates catesbeianus (American bullfrog), hypoxia stimulates gill and lung ventilation during early development. Because accelerated metamorphosis is a useful strategy to escape deterioration of the milieu, we hypothesized that central hypoxia would elicit long-term expression of the lung motor command for air breathing in pre-metamorphic tadpoles (TK stages VI-XIII)...
2018: Advances in Experimental Medicine and Biology
https://www.readbyqxmd.com/read/30357672/a-study-on-the-prediction-method-of-coal-spontaneous-combustion-development-period-based-on-critical-temperature
#13
Lina Qu
Prediction of the development and evolution process of coal spontaneous combustion is of great significance to its prevention and control. Through the testing of different metamorphic degrees coal programmed heating characteristics and the infrared functional groups, the critical temperatures of the coalification process were analyzed and a method to predict the period of spontaneous combustion was established according to the characteristic of the critical temperature change. What can be inferred from this research is that the critical temperature of activation energy of coal in programmed heating experiments can characterize the nature of coal at low temperature and the macrocritical temperature point can be obtained from the characteristics of the activation energy change during the low-temperature period...
October 24, 2018: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/30354024/developmental-maturation-of-functional-coupling-between-ventilatory-oscillators-in-the-american-bullfrog
#14
William M Trask, Mufaddal I Baghdadwala, Richard J A Wilson
Many vital motor behaviors-including locomotion, swallowing, and breathing-appear to be dependent upon the activity of and coordination between multiple endogenously rhythmogenic nuclei, or neural oscillators. Much as the functional development of sensory circuits is shaped during maturation, we hypothesized that coordination of oscillators involved in motor control may likewise be maturation-dependent; i.e., coupling and coordination between oscillators changes over development. We tested this hypothesis using the bullfrog isolated brainstem preparation to study the metamorphic transition of ventilatory motor patterns from early rhythmic buccal (water) ventilation in the tadpole to the mature pattern of rhythmic buccal and lung (air) ventilation in the adult...
October 24, 2018: Developmental Neurobiology
https://www.readbyqxmd.com/read/30344451/magnetism-at-depth-a-view-from-an-ancient-continental-subduction-and-collision-zone
#15
Suzanne A McEnroe, Peter Robinson, Nathan Church, Michael Purucker
Recent sophisticated global data compilations and magnetic surveys have been used to investigate the nature of magnetization in the lower crust and upper mantle. Two approaches to constraining magnetizations are developed, providing minimum (0.01 SI) and maximum (0.04 SI) susceptibility estimates, given some assumed thickness (15+ km here). These values are higher than are found in many continental rocks. Are there rocks deeper in the crust or upper mantle that are more magnetic than expected, or are the model assumptions incomplete? What is the magnetic behavior of deep crustal and upper mantle rocks, when slightly cooler than the Curie or Néel temperatures of their magnetic minerals, after being exhumed from locations of high-grade metamorphism at greater depth? Different sets of equilibrium metamorphic minerals can be considered that would form under different conditions...
April 2018: Geochemistry, Geophysics, Geosystems: G³
https://www.readbyqxmd.com/read/30337730/the-earliest-evidence-for-modern-style-plate-tectonics-recorded-by-hp-lt-metamorphism-in-the-paleoproterozoic-of-the-democratic-republic-of-the-congo
#16
Camille François, Vinciane Debaille, Jean-Louis Paquette, Daniel Baudet, Emmanuelle J Javaux
Knowing which geodynamic regimes characterised the early Earth is a fundamental question. This implies to determine when and how modern plate tectonics began. Today, the tectonic regime is dominated by mobile-lid tectonics including deep and cold subduction. However, in the early Earth (4.5 to 2 Ga) stagnant-lid tectonics may also have occurred. The study of high pressure-low temperature (HP-LT) metamorphic rocks is important, because these rocks are only produced in present-day subduction settings. Here, we characterize the oldest known HP-LT eclogite worldwide (2089 ± 13 Ma; 17-23 kbar/500-550 °C), discovered in the Democratic Republic of the Congo...
October 18, 2018: Scientific Reports
https://www.readbyqxmd.com/read/30333621/reassessing-evidence-of-life-in-3-700-million-year-old-rocks-of-greenland
#17
Abigail C Allwood, Minik T Rosing, David T Flannery, Joel A Hurowitz, Christopher M Heirwegh
The Palaeoarchean supracrustal belts in Greenland contain Earth's oldest rocks and are a prime target in the search for the earliest evidence of life on Earth. However, metamorphism has largely obliterated original rock textures and compositions, posing a challenge to the preservation of biological signatures. A recent study of 3,700-million-year-old rocks of the Isua supracrustal belt in Greenland described a rare zone in which low deformation and a closed metamorphic system allowed preservation of primary sedimentary features, including putative conical and domical stromatolites1 (laminated accretionary structures formed by microbially mediated sedimentation)...
November 2018: Nature
https://www.readbyqxmd.com/read/30324911/high-juvenile-mortality-in-amphibians-during-overwintering-related-to-fungal-pathogen-exposure
#18
Samantha L Rumschlag, Michelle D Boone
The result of pathogen exposures may depend upon trade-offs in energetic demands for immune responses against host growth and survival. Environmental conditions may influence these trade-offs by affecting host size, or trade-offs may change across seasons, altering impacts of pathogens. We exposed northern leopard frog Lithobates pipiens tadpoles to different larval environments (low leaf litter, high density of conspecifics, atrazine, caged fish, or controls) that influenced size at metamorphosis. Subsequently, we exposed metamorphs to Batrachochytrium dendrobatidis (Bd), a fungal pathogen, just after metamorphosis and/or prior to overwintering 12 wk later...
October 16, 2018: Diseases of Aquatic Organisms
https://www.readbyqxmd.com/read/30294788/post-metamorphic-ontogeny-of-zoroaster-fulgens-thomson-1873-asteroidea-forcipulatacea
#19
Marine Fau, Loïc Villier
The complete ontogenetic development of an asteroid skeleton has never been described formally for any species. Here, we describe in detail the post-metamorphic ontogeny of Zoroaster fulgens Thomson, 1873. The major novelty of our work is the description of patterns of plate addition, the ontogeny of the internal ossicles, as well as the variability of ossicles according to their position along series. Seven specimens collected in the Rockall Basin (North Atlantic) were dissected with bleach and their anatomy was documented using a scanning electron microscope...
November 2018: Journal of Anatomy
https://www.readbyqxmd.com/read/30278207/proteomics-reveals-localization-of-cuticular-proteins-in-anopheles-gambiae
#20
Yihong Zhou, Majors J Badgett, Ron Orlando, Judith H Willis
Anopheles gambiae devotes over 2% of its protein coding genes to its 298 structural cuticular proteins (CPs). This paper provides new LC-MS/MS data on two adult structures, proboscises and palps, as well as three larval samples - 4th instar larvae, just their terminal segment, and a preparation enriched in their tracheae. These data were combined with our previously published results of proteins from five other adult structures, whole adults, and two preparations chosen for their relatively clean cuticle, the larval head capsules left behind after ecdysis and the pupal cuticles left behind after adult eclosion...
September 29, 2018: Insect Biochemistry and Molecular Biology
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