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The form and synaptic fine structure of melanopsin-expressing retinal ganglion cells, also called intrinsically photosensitive retinal ganglion cells (ipRGCs), were determined using a new membrane-targeted version of a genetic probe for correlated light and electron microscopy (CLEM). ipRGCs project to multiple brain regions, and because the method labels the entire neuron, it was possible to analyze nerve terminals in multiple retinorecipient brain regions, including the suprachiasmatic nucleus (SCN), olivary pretectal nucleus (OPN), and subregions of the lateral geniculate. Although ipRGCs provide the only direct retinal input to the OPN and SCN, ipRGC terminal arbors and boutons were found to be remarkably different in each target region. A network of dendro-dendritic chemical synapses (DDCSs) was also revealed in the SCN, with ipRGC axon terminals preferentially synapsing on the DDCS-linked cells. The methods developed to enable this analysis should propel other CLEM studies of long-distance brain circuits at high resolution.

SummaryTo expedite the review of semi-automated probability maps of organelles and other features from 3D electron microscopy data we have developed Probability Map Viewer, a Java-based web application that enables the computation and visualization of probability map generation results in near real-time as the data are being collected from the microscope. Probability Map Viewer allows the user to select one or more voxel classifiers, apply them on a sub-region of an active collection, and visualize the results as overlays on the raw data via any web browser using a personal computer or mobile device. Thus, Probability Map Viewer accelerates and informs the image analysis workflow by providing a tool for experimenting with and optimizing dataset-specific segmentation strategies during imaging.Availability and implementationhttps://github.com/crbs/probabilitymapviewer.Contactmellisman@ucsd.edu.Supplementary informationSupplementary data are available at Bioinformatics online.

Astrocytes modulate neuronal activity and inhibit regeneration. We show that cleaved p75 neurotrophin receptor (p75(NTR)) is a component of the nuclear pore complex (NPC) required for glial scar formation and reduced gamma oscillations in mice via regulation of transforming growth factor (TGF)-β signaling. Cleaved p75(NTR) interacts with nucleoporins to promote Smad2 nucleocytoplasmic shuttling. Thus, NPC remodeling by regulated intramembrane cleavage of p75(NTR) controls astrocyte-neuronal communication in response to profibrotic factors.

Electron microscopy (EM) facilitates analysis of the form, distribution, and functional status of key organelle systems in various pathological processes, including those associated with neurodegenerative disease. Such EM data often provide important new insights into the underlying disease mechanisms. The development of more accurate and efficient methods to quantify changes in subcellular microanatomy has already proven key to understanding the pathogenesis of Parkinson's and Alzheimer's diseases, as well as glaucoma. While our ability to acquire large volumes of 3D EM data is progressing rapidly, more advanced analysis tools are needed to assist in measuring precise three-dimensional morphologies of organelles within data sets that can include hundreds to thousands of whole cells. Although new imaging instrument throughputs can exceed teravoxels of data per day, image segmentation and analysis remain significant bottlenecks to achieving quantitative descriptions of whole cell structural organellomes. Here, we present a novel method for the automatic segmentation of organelles in 3D EM image stacks. Segmentations are generated using only 2D image information, making the method suitable for anisotropic imaging techniques such as serial block-face scanning electron microscopy (SBEM). Additionally, no assumptions about 3D organelle morphology are made, ensuring the method can be easily expanded to any number of structurally and functionally diverse organelles. Following the presentation of our algorithm, we validate its performance by assessing the segmentation accuracy of different organelle targets in an example SBEM dataset and demonstrate that it can be efficiently parallelized on supercomputing resources, resulting in a dramatic reduction in runtime.

Aims: This phase I study investigated potential drug–drug interactions of the maturation inhibitor GSK3640254 (GSK'254) with darunavir/ritonavir (DRV/RTV) and/or etravirine (ETR). Methods: In this randomized, open‐label, single‐sequence, multiple‐dose study, healthy participants received GSK'254 200 mg once daily alone or coadministered with DRV/RTV 600/100 mg twice daily (BID; n = 19), ETR 200 mg BID (n = 19) or DRV/RTV 600/100 mg + ETR 200 mg BID (n = 16) under fed conditions. Primary endpoints were steady‐state area under the plasma concentration–time curve from time 0 to the end of the dosing interval (AUC0‐τ) and maximum observed concentration (Cmax). Secondary endpoints included trough concentration (Cτ), safety and tolerability. Pharmacokinetic parameters were calculated using standard noncompartmental analysis, and geometric least‐squares mean ratios were derived from linear mixed‐effects models. Results: GSK'254 AUC0‐τ (geometric least‐squares mean ratio [90% confidence interval], 1.14 [1.00–1.29]), Cmax (1.07 [0.92–1.24]) and Cτ (1.17 [1.01–1.35]) were similar when administered alone and with DRV/RTV. Etravirine coadministration decreased GSK'254 AUC0‐τ (0.53 [0.48–0.59]), Cmax (0.60 [0.53–0.68]) and Cτ (0.51 [0.39–0.66]). Similar reductions were not observed with GSK'254 + DRV/RTV + ETR (AUC0‐τ, 0.94 [0.82–1.09]; Cmax, 0.89 [0.75–1.07]; Cτ, 1.02 [0.89–1.18]). GSK'254 had no meaningful effect on DRV/RTV or ETR concentrations. All reported adverse events (AEs) were grade 1; 3 led to withdrawal and resolved (rash, asymptomatic electrocardiogram T‐wave inversion, periorbital oedema). Most common AEs were diarrhoea (n = 9) and headache (n = 7). No deaths or serious AEs occurred. Conclusion: GSK'254 pharmacokinetics was not meaningfully affected by DRV/RTV or DRV/RTV + ETR, but were reduced with only ETR; no new tolerability concerns were observed. [ABSTRACT FROM AUTHOR]

PurposePostnatal lead exposure produces rod-selective and Bax-mediated apoptosis, decreased scotopic electroretinograms (ERGs), and scotopic and mesopic vision deficits in humans and/or experimental animals. Rod, but not cone, inner segment mitochondria were considered the primary site of action. However, photoreceptor synaptic mitochondria were not examined. Thus, our experiments investigated the structural and functional effects of environmentally relevant postnatal lead exposure on rod spherule and cone pedicle mitochondria and whether Bcl-xL overexpression provided neuroprotection.MethodsC57BL/6N mice pups were exposed to lead only during lactation via dams drinking water containing lead acetate. The blood [Pb] at weaning was 20.6±4.7 µg/dl, which decreased to the control value by 2 months. To assess synaptic mitochondrial structural differences and vulnerability to lead exposure, wild-type and transgenic mice overexpressing Bcl-xL in photoreceptors were used. Electron microscopy, three-dimensional electron tomography, and retinal and photoreceptor synaptic terminal oxygen consumption (QO(2)) studies were conducted in adult control, Bcl-xL, lead, and Bcl-xL/lead mice.ResultsThe spherule and pedicle mitochondria in lead-treated mice were swollen, and the cristae structure was markedly changed. In the lead-treated mice, the mitochondrial cristae surface area and volume (abundance: measure correlated with ATP (ATP) synthesis) were decreased in the spherules and increased in the pedicles. Pedicles also had an increased number of crista segments per volume. In the lead-treated mice, the number of segments/crista and fraction of cristae with multiple segments (branching) similarly increased in spherule and pedicle mitochondria. Lead-induced remodeling of spherule mitochondria produced smaller cristae with more branching, whereas pedicle mitochondria had larger cristae with more branching and increased crista junction (CJ) diameter. Lead decreased dark- and light-adapted photoreceptor and dark-adapted photoreceptor synaptic terminal QO(2). Bcl-xL partially blocked many of the lead-induced alterations relative to controls. However, spherules still had partially decreased abundance, whereas pedicles still had increased branching, increased crista segments per volume, and increased crista junction diameter. Moreover, photoreceptor and synaptic QO(2) were only partially recovered.ConclusionsThese findings reveal cellular and compartmental specific differences in the structure and vulnerability of rod and cone inner segment and synaptic mitochondria to postnatal lead exposure. Spherule and pedicle mitochondria in lead-exposed mice displayed complex and distinguishing patterns of cristae and matrix damage and remodeling consistent with studies showing that synaptic mitochondria are more sensitive to Ca(2+) overload, oxidative stress, and ATP loss than non-synaptic mitochondria. The lead-induced decreases in QO(2) likely resulted from the decreased spherule cristae abundance and smaller cristae, perhaps due to Bax-mediated effects as they occurred in apoptotic rod inner segments. The increase in pedicle cristae abundance and CJ diameter could have resulted from increased Drp1-mediated fission, as small mitochondrial fragments were observed. The mechanisms of Bcl-xL-mediated remodeling might occur via interaction with formation of CJ protein 1 (Fcj1), whereas the partial protection of synaptic QO(2) might result from the enhanced efficiency of energy metabolism via Bcl-xL's direct interaction with the F1F0 ATP synthase and/or regulation of cellular redox status. These lead-induced alterations in photoreceptor synaptic terminal mitochondria likely underlie the persistent scotopic and mesopic deficits in lead-exposed children, workers, and experimental animals. Our findings stress the clinical and scientific importance of examining synaptic dysfunction following injury or disease during development, and developing therapeutic treatments that prevent synaptic degeneration in retinal and neurodegenerative disorders even when apoptosis is blocked.

In this paper, we study the relationship between reconciliations in the Colombian electricity market and the bid prices by firms on the spot market. In this work, we propose a model of behavior of the firm to elaborate theoretical predictions about the relationship between the reconciliations and the bid prices. Subsequently, we developed an empirical strategy to test the predictions of our model. We find that when firms expect their units to have negative reconciliations the next day, they tend to reduce the bid prices for their units. To positive reconciliations, there is no evidence of any relationship. [ABSTRACT FROM AUTHOR]

This study examines the pass-through between retail and wholesale prices of gasoline in Colombia. Data from 2017 to 2019 were available on prices and characteristics of gasoline sold by service stations in the main cities of Colombia. Information on the location of the stations is also available, which is used to georeference the stations and obtain the potential number of competitors for a station. The study results show an asymmetric pass-through behavior between retail and wholesale prices. Furthermore, the potential number of competitors of the stations has a direct effect on the retail prices and an indirect effect because it alters the stations' pass-through. [ABSTRACT FROM AUTHOR]

Abstract: A total of 2561 slash pine (Pinus elliottii Engelm. var. elliottii) grafts were topgrafted in the winter of 2003 and evaluated in January of 2004. The objectives of this [...]