Involvement of selective epithelial cell death in the formation of feather buds on a bioengineered skin

Selective cell death by apoptosis plays important roles in organogenesis. Apoptotic cells are observed in the developmental and homeostatic processes of several ectodermal organs, such as hairs, feathers, and mammary glands. In chick feather development, apoptotic events have been observed during feather morphogenesis, but have not been investigated during early feather bud formation. Previously, we have reported a method for generating feather buds on a bioengineered skin from dissociated skin epithelial and mesenchymal cells in three-dimensional culture. During the development of the bioengineered skin, epithelial cavity formation by apoptosis was observed in the epithelial tissue. In this study, we examined the selective epithelial cell death during the bioengineered skin development. Histological analyses suggest that the selective epithelial cell death in the bioengineered skin was induced by caspase-3-related apoptosis. The formation of feather buds of the bioengineered skin was disturbed by the treatment with a pan-caspase inhibitor. The pan-caspase inhibitor treatment suppressed the rearrangement of the epithelial layer and the formation of dermal condensation, which are thought to be essential step to form feather buds. The suppression of the formation of feather buds on the pan-caspase inhibitor-treated skin was partially compensated by the addition of a GSK-3β inhibitor, which activates Wnt/β-catenin signaling. These results suggest that the epithelial cell death is involved in the formation of feather buds of the bioengineered skin. These observations also suggest that caspase activities and Wnt/β-catenin signaling may contribute to the formation of epithelial and mesenchymal components in the bioengineered skin.

New precise measurements of muonium hyperfine structure at J-PARC MUSE

High precision measurements of the ground state hyperfine structure (HFS) of muonium is a stringent tool for testing bound-state quantum electrodynamics (QED) theory, determining fundamental constants of the muon magnetic moment and mass, and searches for new physics. Muonium is the most suitable system to test QED because both theoretical and experimental values can be precisely determined. Previous measurements were performed decades ago at LAMPF with uncertainties mostly dominated by statistical errors. At the J-PARC Muon Science Facility (MUSE), the MuSEUM collaboration is planning complementary measurements of muonium HFS both at zero and high magnetic field. The new high-intensity muon beam that will soon be available at H-Line will provide an opportunity to improve the precision of these measurements by one order of magnitude. An overview of the different aspects of these new muonium HFS measurements, the current status of the preparation for high-field measurements, and the latest results at zero field are presented.

Clog and Release, and Reverse Motions of DNA in a Nanopore

Motions of circular and linear DNA molecules of various lengths near a nanopore of 100 or 200 nm diameter were experimentally observed and investigated by fluorescence microscopy. The movement of DNA molecules through nanopores, known as translocation, is mainly driven by electric fields near and inside the pores. We found significant clogging of nanopores by DNA molecules, particularly by circular DNA and linear T4 DNA (165.65 kbp). Here, the probabilities of DNA clogging events, depending on the DNA length and shape—linear or circular—were determined. Furthermore, two distinct DNA motions were observed: clog and release by linear T4 DNA, and a reverse direction motion at the pore entrance by circular DNA, after which both molecules moved away from the pore. Finite element method-based numerical simulations were performed. The results indicated that DNA molecules with pores 100–200 nm in diameter were strongly influenced by opposing hydrodynamic streaming flow, which was further enhanced by bulky DNA configurations.

Analysis of future climate change impacts on snow distribution over mountainous watersheds in Northern California by means of a physically-based snow distribution model

The impacts of climate change on snow distribution through the 21st century were investigated over three mountainous watersheds in Northern California by means of a physically-based snow distribution model. The future climate conditions during a 90-year future period from water year 2010 to 2100 were obtained from 13 future climate projection realizations from two GCMs (ECHAM5 and CCSM3) based on four SRES scenarios (A1B, A1FI, A2, and B1). The 13 future climate projection realizations were dynamically downscaled at 9 km resolution by a regional climate model. Using the downscaled variables based on the 13 future climate projection realizations, snow distribution over the Feather, Yuba, and American River watersheds (FRW, YRW, and ARW) was projected by means of the physically-based snow model. FRW and YRW watersheds cover the main source areas of the California State Water Project (SWP), and ARW is one of the key watersheds in the California Central Valley Project (CVP). SWP and CVP are of great importance as they provide and regulate much of the California's water for drinking, irrigation, flood control, environmental, and hydro-power generation purposes. Ensemble average snow distribution over the study watersheds was calculated over the 13 realizations and for each scenario, revealing differences among the scenarios. While the snow reduction through the 21st century was similar between A1B and A2, the snow reduction was milder for B1, and more severe for A1FI. A significant downward trend was detected in the snowpack over nearly the entire watershed areas for all the ensemble average results.

Muons at ISIS

For the last 30 years, muon experiments at ISIS pulsed neutron and muon facility at the Rutherford Appleton Laboratory, Oxfordshire have been making a significant contribution to a number of scientific fields. The muon facilities at ISIS consist of eight experimental areas. The European Commission Muon facility consists of three experimental areas with a fixed momentum (28 MeV c^-1). The RIKEN-RAL facility has a variable momentum (17-90 MeV c^-1) and a choice of negative or positive muons delivering muons to four experimental areas. There is also an area recently used for a muon ionization cooling experiment. In this paper, the ISIS pulsed muon facilities are reviewed, including the beam characteristics that could be useful for muography experiments.This article is part of the Theo Murphy meeting issue 'Cosmic-ray muography'.

Mid-axillary pacemaker re-implantation after contralateral pocket infection in an emaciated elderly case

The number of implantations of cardiac implantable electrophysiological devices (CIEDs) has increased over the past several years. However, the aging population and expansion of indications for CIEDs have led to an increase in associated infections. We experienced a case of a 99-year-old man presenting with skin erosion at the pocket site, where a 6-month-old implantable pacemaker was replaced. He was referred for pacemaker pocket infection and presented with fever accompanied by pain and swelling around pacemaker generator. We could not explant 7-year-old pacemaker leads and the patient refused to undergo either laser lead extraction or surgical removal. We planned to re-implant in the contralateral chest. However, the patient was emaciated with low body-mass-index (15.2 kg/m²), thus concerns arose about the possibility of tissue disruption and re-infection owing to thin skin and absence of sufficient subcutaneous tissue in contralateral subclavian region. Axillary placement of CIEDs has been adopted in patients with limited venous access. We applied a mid-axillary pacemaker implant procedure to this elderly and emaciated patient. Postoperative clinical course was uneventful. After discharge, no history of unexplained fever or illness was recorded. Mid-axillary pacemaker pocket could be an alternative approach for re-implantation in patients with emaciated, cachexic, or limited pocket preparation. <Learning objective: We apply the mid-axillary pacemaker implant procedure to a nonagenarian with contralateral pacemaker infection to minimize the risk of skin disruption after implantation. This implies that implantation is possible in patients with emaciated or cachexic or infection of the contralateral subclavian pocket. Mid-axillary pacemaker pocket could be an alternative approach for re-implantation in patients with emaciated, cachexic, or limited pocket preparation.> .

In vitro formation of the Merkel cell-neurite complex in embryonic mouse whiskers using organotypic co-cultures

A Merkel cell-neurite complex is a touch receptor composed of specialized epithelial cells named Merkel cells and peripheral sensory nerves in the skin. Merkel cells are found in touch-sensitive skin components including whisker follicles. The nerve fibers that innervate Merkel cells of a whisker follicle extend from the maxillary branch of the trigeminal ganglion. Whiskers as a sensory organ attribute to the complicated architecture of the Merkel cell-neurite complex, and therefore it is intriguing how the structure is formed. However, observing the dynamic process of the formation of a Merkel cell-neurite complex in whiskers during embryonic development is still difficult. In this study, we tried to develop an organotypic co-culture method of a whisker pad and a trigeminal ganglion explant to form the Merkel cell-neurite complex in vitro. We initially developed two distinct culture methods of a single whisker row and a trigeminal ganglion explant, and then combined them. By dissecting and cultivating a single row from a whisker pad, the morphogenesis of whisker follicles could be observed under a microscope. After the co-cultivation of the whisker row with a trigeminal ganglion explant, a Merkel cell-neurite complex composed of Merkel cells, which were positive for both cytokeratin 8 and SOX2, Neurofilament-H-positive trigeminal nerve fibers and Schwann cells expressing Nestin, SOX2 and SOX10 was observed via immunohistochemical analyses. These results suggest that the process for the formation of a Merkel cell-neurite complex can be observed under a microscope using our organotypic co-culture method.

Depth dependant element analysis of PbMg1/3Nb2/3O3 using muonic x-rays

The relaxor PbMg_1/3Nb_2/3O₃ (PMN) has received attention due to its potential applications as a piezoelectric when doped with PbTiO₃ (PT). Previous results have found that there are two phases existing in the system, one linked to the near-surface regions of the sample, the other in the bulk. However, the exact origin of these two phases is unclear. In this paper, depth dependant analysis results from negative muon implantation experiments are presented. It is shown that the Pb content is constant throughout all depths probed in the sample, but the Mg and Nb content changes in the near-surface region below 100 μm. At an implantation depth of 60 μm, it is found that there is a 25% increase in Mg content, with a simultaneous 5% decrease in Nb content in order to maintain charge neutrality. These results show that the previously observed skin effects in PMN are due to a change in concentration and unit cell.

Role of the boundary in feather bud formation on one-dimensional bioengineered skin

The role of a boundary in pattern formation from a homogenous state in Turing's reaction–diffusion equations is important, particularly when the domain size is comparable to the pattern scale. Such experimental conditions may be achieved for in vitro regeneration of ectodermal appendages such as feathers, via reconstruction of embryonic single cells. This procedure can eliminate a predefined genetic map, such as the midline of chick feather bud formation, leaving uniformly distributed identical cells as a bioengineered skin. Here, the self-organizing nature of multiple feather bud formation was examined in bioengineered 1D-skin samples. Primal formation of feather buds occurred at a fixed length from the skin edge. This formation was numerically recapitulated by a standard two-component reaction-diffusion model, suggesting that the boundary effect caused this observation. The proper boundary conditions were nonstandard, either mixed Dirichlet–Neumann or partial-flux. In addition, the model implies imperfect or hindered bud formation as well as nearly equal distances between buds. In contrast, experimental observations indicated that the skin curvature, which was not included in our model, also strongly affected bud formation. Thus, bioengineered skin may provide an ideal template for modeling a self-organized process from a homogenous state. This study will examine the possible diffusion activities of activator or inhibitor molecular candidates and mechanical activities during cell aggregation, which will advance our understanding of skin appendage regeneration from pluripotent or embryonic stem cells.

Gate-Voltage-Controlled Threading DNA into Transistor Nanopores

We present a simple method for DNA translocation driven by applying AC voltages, such as square and sawtooth waves, on an embedded thin film as a gate electrode inside of a dielectric nanopore, without applying a conventional bias voltage externally across the pore membrane. Square waveforms on a gate can drive a single DNA molecule into a nanopore, which often returns from the pore, causing an oscillation across the membrane. An optimized sawtooth-like negative voltage pulse on the gate can thread a fraction of a DNA molecule into a pore after a single pulse. This trapped DNA molecule continues to finish its translocation slowly through the pore. The DNA's slow speed was comparable to previous findings of the escaping DNA speed from a nanopore estimated by the Smoluchowski equation with excluded-volume interactions of a long-chain molecule and electrophoresis by extremely low electric fields. This simple scheme, controlling DNA molecules only by gate potential modulation at a nanopore, will provide an additional method to thread, translocate, or oscillate a single biomolecule at a gated nanopore.

Site-specific randomization of the endogenous genome by a regulatable CRISPR-Cas9 piggyBac system in human cells

Randomized mutagenesis at an endogenous chromosomal locus is a promising approach for protein engineering, functional assessment of regulatory elements, and modeling genetic variations. In mammalian cells, however, it is challenging to perform site-specific single-nucleotide substitution with single-stranded oligodeoxynucleotide (ssODN) donor templates due to insufficient homologous recombination and the infeasibility of positive selection. Here, we developed a DNA transposon based CRISPR-Cas9 regulated transcription and nuclear shuttling (CRONUS) system that enables the stable transduction of CRISPR-Cas9/sgRNA in broad cell types, but avoids undesired genome cleavage in the absence two chemical inducing molecules. Highly efficient single nucleotide alterations induced randomization of desired codons (up to 4 codons) at a defined genomic locus in various human cell lines, including human iPS cells. Thus, CRONUS provides a novel platform for modeling diseases and genetic variations.

Maximizing T c by tuning nematicity and magnetism in FeSe1-x S x superconductors

A fundamental issue concerning iron-based superconductivity is the roles of electronic nematicity and magnetism in realising high transition temperature (T c). To address this issue, FeSe is a key material, as it exhibits a unique pressure phase diagram involving non-magnetic nematic and pressure-induced antiferromagnetic ordered phases. However, as these two phases in FeSe have considerable overlap, how each order affects superconductivity remains perplexing. Here we construct the three-dimensional electronic phase diagram, temperature (T) against pressure (P) and isovalent S-substitution (x), for FeSe1-x S x . By simultaneously tuning chemical and physical pressures, against which the chalcogen height shows a contrasting variation, we achieve a complete separation of nematic and antiferromagnetic phases. In between, an extended non-magnetic tetragonal phase emerges, where T c shows a striking enhancement. The completed phase diagram uncovers that high-T c superconductivity lies near both ends of the dome-shaped antiferromagnetic phase, whereas T c remains low near the nematic critical point.

Impaired myocardial microcirculation in the flow-glucose metabolism mismatch regions in revascularized acute myocardial infarction

BACKGROUND

In successfully revascularized acute myocardial infarction (AMI), microvascular function in a myocardial flow-glucose metabolism mismatch pattern has not been reported. We aimed to elucidate myocardial flow reserve (MFR) and myocardial viability in mismatch segments.

METHODS

18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and adenosine stress 13N-ammonia PET were performed in eighteen AMI patients to evaluate myocardial glucose metabolism, myocardial blood flow (MBF), and MFR. Infarct segments were classified into 3 groups: normal (preserved resting MBF), mismatch (preserved FDG uptake but reduced resting MBF), and match (reduced FDG uptake and resting MBF). Regional wall motion score (WMS) was assessed immediately after reperfusion and recovery periods.

RESULTS

MFR in the mismatch group was significantly lower than that in non-infarct-related segments (1.655 ± 0.516 vs 2.282 ± 0.629, P < .01) and similar to that in the match group (1.635 ± 0.528, P = .999). WMS in the mismatch group was significantly improved (3.07 ± 0.48 vs 2.07 ± 1.14, P = .003); however, in recovery periods, WMS in the mismatch group was significantly higher than that in the normal group (1.05 ± 1.04, P < .01).

CONCLUSIONS

In successfully revascularized AMI, microvascular function is impaired despite preserved myocardial glucose metabolism in mismatch segments.

Trend analysis of watershed-scale precipitation over Northern California by means of dynamically-downscaled CMIP5 future climate projections

The impacts of climate change on watershed-scale precipitation through the 21st century were investigated over eight study watersheds in Northern California based on dynamically downscaled CMIP5 future climate projections from three GCMs (CCSM4, HadGEM2-ES, and MIROC5) under the RCP4.5 and RCP8.5 future climate scenarios. After evaluating the modeling capability of the WRF model, the six future climate projections were dynamically downscaled by means of the WRF model over Northern California at 9km grid resolution and hourly temporal resolution during a 94-year period (2006-2100). The biases in the model simulations were corrected, and basin-average precipitation over the eight study watersheds was calculated from the dynamically downscaled precipitation data. Based on the dynamically downscaled basin-average precipitation, trends in annual depth and annual peaks of basin-average precipitation during the 21st century were analyzed over the eight study watersheds. The analyses in this study indicate that there may be differences between trends of annual depths and annual peaks of watershed-scale precipitation during the 21st century. Furthermore, trends in watershed-scale precipitation under future climate conditions may be different for different watersheds depending on their location and topography even if they are in the same region.