In order to observe and quantify long-range neuronal connections in intact mouse brain by light microscopy, it is first necessary to clear the brain, thus suppressing refractive-index variations. ...Here we describe a method that clears the brain and preserves the signal from proteinaceous fluorophores using a pH-adjusted non-aqueous index-matching medium. Successful clearing is enabled through the use of either 1-propanol or tert-butanol during dehydration whilst maintaining a basic pH. We show that high-resolution fluorescence imaging of entire, structurally intact juvenile and adult mouse brains is possible at subcellular resolution, even following many months in clearing solution. We also show that axonal long-range projections that are EGFP-labelled by modified Rabies virus can be imaged throughout the brain using a purpose-built light-sheet fluorescence microscope. To demonstrate the viability of the technique, we determined a detailed map of the monosynaptic projections onto a target cell population in the lateral entorhinal cortex. This example demonstrates that our method permits the quantification of whole-brain connectivity patterns at the subcellular level in the uncut brain.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
ABSTRACT We report observations of resolved C2H emission rings within the gas-rich protoplanetary disks of TW Hya and DM Tau using the Atacama Large Millimeter Array. In each case the emission ring ...is found to arise at the edge of the observable disk of millimeter-sized grains (pebbles) traced by submillimeter-wave continuum emission. In addition, we detect a C3H2 emission ring with an identical spatial distribution to C2H in the TW Hya disk. This suggests that these are hydrocarbon rings (i.e., not limited to C2H). Using a detailed thermo-chemical model we show that reproducing the emission from C2H requires a strong UV field and C/O > 1 in the upper disk atmosphere and outer disk, beyond the edge of the pebble disk. This naturally arises in a disk where the ice-coated dust mass is spatially stratified due to the combined effects of coagulation, gravitational settling and drift. This stratification causes the disk surface and outer disk to have a greater permeability to UV photons. Furthermore the concentration of ices that transport key volatile carriers of oxygen and carbon in the midplane, along with photochemical erosion of CO, leads to an elemental C/O ratio that exceeds unity in the UV-dominated disk. Thus the motions of the grains, and not the gas, lead to a rich hydrocarbon chemistry in disk surface layers and in the outer disk midplane.
The hypothalamic neuropeptide oxytocin (OT), which controls childbirth and lactation, receives increasing attention for its effects on social behaviors, but how it reaches central brain regions is ...still unclear. Here we gained by recombinant viruses selective genetic access to hypothalamic OT neurons to study their connectivity and control their activity by optogenetic means. We found axons of hypothalamic OT neurons in the majority of forebrain regions, including the central amygdala (CeA), a structure critically involved in OT-mediated fear suppression. In vitro, exposure to blue light of channelrhodopsin-2-expressing OT axons activated a local GABAergic circuit that inhibited neurons in the output region of the CeA. Remarkably, in vivo, local blue-light-induced endogenous OT release robustly decreased freezing responses in fear-conditioned rats. Our results thus show widespread central projections of hypothalamic OT neurons and demonstrate that OT release from local axonal endings can specifically control region-associated behaviors.
► We constructed a virus to express any protein, e.g., ChR2, only in oxytocin neurons ► Fluorescent oxytocin neurons project simultaneously to the forebrain and pituitary ► Blue-light exposure of oxytocin axons in vitro affects amygdala neuronal activity ► Blue-light amygdala exposure in vivo evokes oxytocin-mediated decreases in fear
To address the role of the hypothalamic oxytocin (OT)-expressing neurons, Knobloch et al. expressed channelrhodopsin-2 in these neurons. OT neurons project to the central amygdala, as well as other forebrain regions, and activation of these neurons induced oxytocin release and freezing responses in fear-conditioned rats.
We propose that many of the complex morpho-logical phenomena observed during nanowire growth arise from the interplay of just three elementary processes: facet growth, droplet statics, and the ...introduction of new facets. We incorporate these processes into an explicit model for the vapor−liquid−solid growth of fully faceted nanowires. In numerical simulations with this model, different conditions can lead to either growth of a free-standing wire or lateral growth where the catalyst droplet crawls along the surface. An external perturbation can cause the wire to kink into a different direction. Different growth conditions can also change the shape of the growth tip. All of these phenomena have been observed, and the model behavior is consistent with the experimental observations.
This paper explores the use of aligned chemical vapour deposition (CVD)-grown multi-wall carbon nanotubes as a conductive filler in an epoxy system based on a bisphenol-A resin and an amine hardener. ...During the production of composite samples containing 0.01 wt% nanotubes, stirring rates, resin temperatures, and curing temperatures were varied. Optical microscopy of bulk samples was used to classify the degree of nanotube agglomeration. In addition, the specific bulk conductivity of the materials was analysed by AC impedance spectroscopy. The resulting electrical properties of the composites ranged from purely dielectric behaviour to bulk conductivities of 10
−3 Sm
−1 and were found to depend strongly on three separate stages during processing. All samples contained individually dispersed carbon nanotubes after initial shear-intensive stirring. Negative surface charges on the nanotubes led to charge-stabilised dispersions. After the addition of the hardener, the nanotubes reaggregated upon application of elevated temperatures and/or modest shear forces. The formation of the final network depended on the curing temperature of the matrix. The experimental results are compared to previous studies on nanotube and carbon black epoxy composites and are discussed with respect to aspects of colloid theory.
Here, we utilized spontaneous models of pancreatic and lung cancer to examine how neoantigenicity shapes tumor immunity and progression. As expected, neoantigen expression during lung adenocarcinoma ...development leads to T cell-mediated immunity and disease restraint. By contrast, neoantigen expression in pancreatic ductal adenocarcinoma (PDAC) results in exacerbation of a fibro-inflammatory microenvironment that drives disease progression and metastasis. Pathogenic TH17 responses are responsible for this neoantigen-induced tumor progression in PDAC. Underlying these divergent T cell responses in pancreas and lung cancer are differences in infiltrating conventional dendritic cells (cDCs). Overcoming cDC deficiency in early-stage PDAC leads to disease restraint, while restoration of cDC function in advanced PDAC restores tumor-restraining immunity and enhances responsiveness to radiation therapy.
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•Neoantigen expression elicits pathogenic T cell response accelerating PDAC•cDC dysfunction precludes early TH1 and CTL response to PDAC neoantigens•Increasing cDCs in early PDAC lesions restores anti-tumor T cell immunity•Restoring cDC function in advanced PDAC improves efficacy of radiation therapy
Hegde et al. identify divergent T cell responses in lung cancer and pancreatic ductal adenocarcinoma (PDAC) caused by differences in conventional dendritic cell (cDC) infiltration. Mobilization of cDCs in PDAC models enhances CD8+ T cell and TH1 activity to reduce tumor growth and increase response to therapy.
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