Cosmic kidney disease: an integrated pan-omic, physiological and morphological study into spaceflight-induced renal dysfunction.

Missions into Deep Space are planned this decade. Yet the health consequences of exposure to microgravity and galactic cosmic radiation (GCR) over years-long missions on indispensable visceral organs such as the kidney are largely unexplored. We performed biomolecular (epigenomic, transcriptomic, proteomic, epiproteomic, metabolomic, metagenomic), clinical chemistry (electrolytes, endocrinology, biochemistry) and morphometry (histology, 3D imaging, miRNA-ISH, tissue weights) analyses using samples and datasets available from 11 spaceflight-exposed mouse and 5 human, 1 simulated microgravity rat and 4 simulated GCR-exposed mouse missions. We found that spaceflight induces: 1) renal transporter dephosphorylation which may indicate astronauts' increased risk of nephrolithiasis is in part a primary renal phenomenon rather than solely a secondary consequence of bone loss; 2) remodelling of the nephron that results in expansion of distal convoluted tubule size but loss of overall tubule density; 3) renal damage and dysfunction when exposed to a Mars roundtrip dose-equivalent of simulated GCR.

Connection between Carbon Incorporation and Growth Rate for GaN Epitaxial Layers Prepared by OMVPE.

Carbon, a compensator in GaN, is an inherent part of the organometallic vapor phase epitaxy (OMVPE) environment due to the use of organometallic sources. In this study, the impact of growth conditions are explored on the incorporation of carbon in GaN prepared via OMVPE on pseudo-bulk GaN wafers (in several cases, identical growths were performed on GaN-on-Al2O3 templates for comparison purposes). Growth conditions with different growth efficiencies but identical ammonia molar flows, when normalized for growth rate, resulted in identical carbon incorporation. It is concluded that only trimethylgallium which contributes to growth of the GaN layer contributes to carbon incorporation. Carbon incorporation was found to decrease proportionally with increasing ammonia molar flow, when normalized for growth rate. Ammonia molar flow divided by growth rate is proposed as a reactor independent predictor of carbon incorporation as opposed to the often-reported input V/III ratio. A low carbon concentration of 7.3 × 1014 atoms/cm3 (prepared at a growth rate of 0.57 µm/h) was obtained by optimizing growth conditions for GaN grown on pseudo-bulk GaN substrates.

Recent advances in fluorescence correlation spectroscopy.

Fluorescence correlation spectroscopy is a method in which fluctuations in the fluorescence arising from a very small sample volume are correlated to obtain information about the processes giving rise to the fluctuations. Recent progress has been made in methodologies such as two-photon excitation, photon counting histogram analysis, cross-correlation, image correlation and evanescent excitation. Fluorescence correlation spectroscopy techniques have been applied to several biological processes, including fluorescent protein photodynamics, binding equilibria and kinetics, protein oligomerization, nucleic acid interactions, and membrane and intracellular dynamics.

Comparison of Murine Cervicovaginal Infection by Chlamydial Strains: Identification of Extrusions Shed In vivo.

Chlamydia trachomatis is the leading cause of bacterial sexually transmitted infections (STIs) and preventable blindness. Untreated, asymptomatic infection as well as frequent re-infection are common and may drive pelvic inflammatory disease, ectopic pregnancy, and infertility. In vivo models of chlamydial infection continue to be instrumental in progress toward a vaccine and further elucidating the pathogenesis of this intracellular bacterium, however significant gaps in our understanding remain. Chlamydial host cell exit occurs via two mechanisms, lysis and extrusion, although the latter has yet to be reported in vivo and its biological role is unclear. The objective of this study was to investigate whether chlamydial extrusions are shed in vivo following infection with multiple strains of Chlamydia. We utilized an established C3H/HeJ murine cervicovaginal infection model with C. trachomatis serovars D and L2 and the Chlamydia muridarum strain MoPn to monitor the (i) time course of infection and mode of host cell exit, (ii) mucosal and systemic immune response to infection, and (iii) gross and histopathology following clearance of active infection. The key finding herein is the first identification of chlamydial extrusions shed from host cells in an in vivo model. Extrusions, a recently appreciated mode of host cell exit and potential means of dissemination, had been previously observed solely in vitro. The results of this study demonstrate that chlamydial extrusions exist in vivo and thus warrant further investigation to determine their role in chlamydial pathogenesis.

An NMR shielding model for protons above the plane of a carbonyl group.

Covalently bonded hydrogen nuclei located over the plane of a carbonyl group in a strong magnetic field experience magnetic shielding (or deshielding) that results from the combined effect of the magnetic anisotropy of the carbon-oxygen double bond and various other intramolecular shielding effects. GIAO-HF in Gaussian 98 was employed to calculate isotropic shielding values and to predict the net proton NMR shielding increment for a simple model system: the proximate proton of methane held in various positions over formaldehyde. The net shielding increments of the proximate proton of methane, plotted against its Cartesian coordinates relative to the center of the carbon-oxygen double bond, led to the development of a single empirical equation for predicting the NMR shielding experienced by a covalently bonded proton over the plane of a carbonyl group. The predictive capability of this equation has been validated by calculating the shielding increments of protons over the plane of a carbonyl group in known structures, using this as a correction to the chemical shift estimated by subtituent effects and comparing the result to experimentally observed chemical shifts. Shielding is predicted by this equation for protons located in the region from over the center of the carbon-oxygen double bond to beyond the carbon atom; deshielding is predicted for protons located above and beyond the oxygen atom. This prediction differs from those made by the long-held "shielding cone" model found in nearly every textbook on NMR, but is consistent with experimental observations. The algorithm for predicting the shielding increment for a proton over a carbonyl group can be used in a spreadsheet or incorporated into software that estimates chemical shifts using additive substituent constants or a database of structures. Its use can improve the accuracy of the estimated chemical shift of a proton in the vicinity of a carbon-oxygen double bond, and thus assist in spectral assignments and in correct structure determination.

Ligand binding by estrogen receptor beta attached to nanospheres measured by fluorescence correlation spectroscopy.

Although many indirect methods have been chosen to study the system of estrogen receptor ligand binding, an ideal method is fluorescence correlation spectroscopy (FCS). FCS is nondestructive to the sample, uses very small sample volumes, and operates well within physiological concentration ranges. The methodology was developed to biotinylate the estrogen receptor beta-ligand binding domain (ERbeta-LBD) using biotin with a very short spacer and to then attach this protein to a 40 nm neutravidin-coated bead (nanosphere). Diffusional FCS data were obtained for a fluorescently labeled coactivator peptide, steroid receptor coactivator peptide-1 (A-SRC-1(2)), in the absence and presence of bead-bound ERbeta-LBD. Data were also acquired in the presence of one of the endogenous ligands for ERbeta, 17beta-estradiol, and with tamoxifen. The bead strategy resulted in a decreased receptor diffusion coefficient and consequent increase in the decay time of the FCS autocorrelation functions for receptor-bound, labeled SRC-1(2). Thus, free and bound coactivators were much more readily distinguished by FCS. Discrimination between the fluorescently labeled unbound and bound species could be determined in autocorrelation functions obtained in as few as 30 s. The advantage of using FCS with the ERbeta-LBD: bead methodology is the ability to obtain reliable and reproducible data in a short time frame.