Sulfide inhibits oxygenic photosynthesis by blocking electron transfer between H
O and the oxygen-evolving complex in the D1 protein of Photosystem II. The ability of cyanobacteria to counter this ...effect has implications for understanding the productivity of benthic microbial mats in sulfidic environments throughout Earth history. In Lake Fryxell, Antarctica, the benthic, filamentous cyanobacterium
creates a 1-2 mm thick layer of 50 µmol L
O
in otherwise sulfidic water, demonstrating that it sustains oxygenic photosynthesis in the presence of sulfide. A metagenome-assembled genome of
indicates a genetic capacity for oxygenic photosynthesis, including multiple copies of
(encoding the D1 protein of Photosystem II), and anoxygenic photosynthesis with a copy of
(encoding the sulfide quinone reductase protein that oxidizes sulfide). The genomic content of
is consistent with sulfide tolerance mechanisms including increasing
expression or directly oxidizing sulfide with sulfide quinone reductase. However, the ability of the organism to reduce Photosystem I via sulfide quinone reductase while Photosystem II is sulfide-inhibited, thereby performing anoxygenic photosynthesis in the presence of sulfide, has yet to be demonstrated.
The evolution of oxygenic photosynthesis was one of the most transformative evolutionary events in Earth’s history, leading eventually to the oxygenation of Earth’s atmosphere and, consequently, the ...evolution of aerobic respiration. Previous work has shown that the terminal electron acceptors (complex IV) of aerobic respiration likely evolved after the evolution of oxygenic photosynthesis. However, complex I of the respiratory complex chain can be involved in anaerobic processes and, therefore, may have pre-dated the evolution of oxygenic photosynthesis. If so, aerobic respiration may have built upon respiratory chains that pre-date the rise of oxygen in Earth’s atmosphere. The Melainabacteria provide a unique opportunity to examine this hypothesis because they contain genes for aerobic respiration but likely diverged from the Cyanobacteria before the evolution of oxygenic photosynthesis. Here, we examine the phylogenies of translated complex I sequences from 44 recently published Melainabacteria metagenome assembled genomes and genomes from other Melainabacteria, Cyanobacteria, and other bacterial groups to examine the evolutionary history of complex I. We find that complex I appears to have been present in the common ancestor of Melainabacteria and Cyanobacteria, supporting the idea that aerobic respiration built upon respiratory chains that pre-date the evolution of oxygenic photosynthesis and the rise of oxygen.
Abstract Cardiac hypertrophy has been well-characterized at the level of transcription. During cardiac hypertrophy, genes normally expressed primarily during fetal heart development are re-expressed, ...and this fetal gene program is believed to be a critical component of the hypertrophic process. Recently, alternative splicing of mRNA transcripts has been shown to be temporally regulated during heart development, leading us to consider whether fetal patterns of splicing also reappear during hypertrophy. We hypothesized that patterns of alternative splicing occurring during heart development are recapitulated during cardiac hypertrophy. Here we present a study of isoform expression during pressure-overload cardiac hypertrophy induced by 10 days of transverse aortic constriction (TAC) in rats and in developing fetal rat hearts compared to sham-operated adult rat hearts, using high-throughput sequencing of poly(A) tail mRNA. We find a striking degree of overlap between the isoforms expressed differentially in fetal and pressure-overloaded hearts compared to control: forty-four percent of the isoforms with significantly altered expression in TAC hearts are also expressed at significantly different levels in fetal hearts compared to control ( P < 0.001). The isoforms that are shared between hypertrophy and fetal heart development are significantly enriched for genes involved in cytoskeletal organization, RNA processing, developmental processes, and metabolic enzymes. Our data strongly support the concept that mRNA splicing patterns normally associated with heart development recur as part of the hypertrophic response to pressure overload. These findings suggest that cardiac hypertrophy shares post-transcriptional as well as transcriptional regulatory mechanisms with fetal heart development.
•We explore a novel W/Si/Ge composite system for thermoelectric applications.•The influence of crucible selection on electrical properties is investigated.•Introduction of W can reduce the expensive ...Ge component of the alloy.
Thermoelectric properties of the W/Si/Ge alloy system have been investigated with varying concentration levels of germanium and tungsten. The alloys were fabricated by directional solidification with the Bridgman method using boron nitride and fused silica crucibles. The effect of crucible contamination was investigated and found to result in doping the system to suitable levels for thermoelectric applications. The system has been demonstrated as a suitable high temperature p-type thermoelectric material exhibiting high power factors, >3000μW/mK2. Seebeck coefficients of the system are on the order of +300μV/K and electrical conductivities of 2.8×104S/m at the optimum operating temperature. The best composition, 0.9at% W/9.3at% Ge, achieved a figure of merit comparable to RTG values over the temperature range of interest. The results suggest that W addition can reduce the use of expensive Ge component of the alloy. Reported are the details of processing conditions, microstructure development, and temperature dependent thermoelectric properties. The material system was stable at the temperatures required for NASA’s radioisotope thermoelectric generators.
•We introduce a Device Design Factor to account for thermal losses of a thermoelectric couple.•We introduce a Fin Factor to account for lateral heat transfer in a thermoelectric couple.•Conversion ...efficiency is analytically derived in terms of new design parameters.
An analytic solution of a thermocouple has been developed in order to gain a deeper understanding of the physics of a real device. The model is established for both rectangular and cylindrical couples and is made to account for thermal resistance of the hot and cold shoes and lateral heat transfer. A set of dimensionless parameters have been developed to determine couple behavior and serve as simplifying justifications. New dimensionless parameters, Device Design Factor and Fin Factor, are introduced to account for the thermal resistance and lateral heat transfer, respectively. Design guidelines on couple length and cross-sectional area have been established to account for conditions encountered by a realistic couple. As a result of thermal resistances a lower limit on the length of the couple can be established. In the case of a lateral heat transfer couple the efficiency is found to depend upon cross-sectional area of the leg in such a fashion as to suggest the need to design large area couples. The classic thermoelectric solution neglects the effect of thermal resistance and lateral heat transfer, leading to an over estimated conversion efficiency. The work presented provides a path to incorporate these neglected factors and offers a simplified estimation for couple performance based on analytic solutions of governing equations.
Nonalcoholic steatohepatitis (NASH) is an emerging health crisis with no approved therapies. Obeticholic acid (OCA), a farnesoid X receptor (FXR) agonist, shows promise in NASH trials. However, the ...precise mechanisms mediating OCA effects and impact on cholesterol metabolism are not fully understood. We explored the pharmaco-toxicological effects of OCA on patho-physiological pathways in hepatocytes using a previously described perfused organotypic liver system that allows culture in near-physiological insulin/glucose milieus, and exhibits drug responses at clinically-relevant concentrations. Primary hepatocytes experienced 48-hour exposure to OCA at concentrations approximating therapeutic (0.5μM) and supratherapeutic (10μM) levels. Global transcriptomics by RNAseq was complimented by cellular viability (MTT), CYP activity assays, and secreted FGF19 levels in the media. Dose-dependent, transcriptional effects suggested suppression of bile acid synthesis (↓CYP7A1, ↓CYP27A1) and increased bile efflux (↑ABCB4, ↑ABCB11, ↑OSTA, ↑OSTB). Pleiotropic effects included suppression of TGFβ and IL-6 signaling pathways, and signatures suggestive of HDL suppression (↑SCARB1, ↓ApoAI, ↓LCAT) and LDL elevation (↑ApoB, ↓CYP7A1). OCA exhibited direct FXR-mediated effects with increased FGF19 secretion. Transcriptomics revealed regulation of metabolic, anti-inflammatory, and anti-fibrotic pathways beneficial in NASH, and predicted cholesterol profiles consistent with clinical findings. Follow-up studies under lipotoxic/inflammatory conditions would corroborate these effects in a disease-relevant environment.
•Clinical concentrations of obeticholic acid were tested in an organotypic liver model.•Transcriptomics reveal metabolic pathway effects beneficial in fatty liver disease.•Changes predictive of lipoprotein abnormalities were also noted.•Cytochrome P450 effects raise concern for potential drug-drug interactions.
As living standards around the world improve and metal consumption increases, extracting raw materials will likely become more challenging in the future. Although already part of the general metal ...supply stream, metal recycling has to increase if we are to build a more sustainable society. With the recent widespread adoption of a range of consumer and industrial electronics, the recycling of the so-called electronic scrap (“e-scrap”) has also increased in importance. One of the leading technologies for the recycling of e-scrap and copper scrap is the ISASMELT™ Top Submerged Lance technology. This article describes new opportunities for the U.S. recycling industry to yield full value from collected, sorted, and separated waste metals, in particular, e-scrap and lower grade copper scrap by the use of ISASMELT™ technology. The article includes the description of a case study example of a regional, compact ISASMELT™ plant in the United States treating a blend of e-scrap and copper scrap, having a total feed capacity of 75000 t/year of feed. Plants of higher or lower capacity are also discussed.
Background
The national Stepping Up Initiative has attracted over 500 counties interested in reducing the use of jail for individuals with mental health disorders. This paper identifies ...socioeconomic, criminal legal, and health care factors that predict the likelihood of counties joining Stepping Up.
Results
After performing variable selection, logistic regression models were performed on 3,141 U.S. counties. Counties designated as medically underserved and/or mental health staffing shortage areas were less likely to participate in this initiative. Logistic regression models showed that larger counties (populations over 250,000) with better health care infrastructure, more mental health providers per capita, higher percent of Medicaid funded drug treatment services, and at least one medical school, were more likely to join Stepping Up. These counties had lower per capita jail populations, higher concentration of police resources, and higher pretrial incarceration rate.
Conclusions
County-level health care delivery factors are major contributors to a county’s likelihood, or willingness, of engaging in Stepping Up reform efforts to reduce jail population with mental health disorders issues. Therefore, improving availability and accessibility of medical and behavioral health care in different communities, may facilitate efforts to address the unnecessary incarceration of individuals with mental health disorders.
The discovery of a hyper metal-poor star with total metallicity of ≤10−5 Z⊙ has motivated new investigations of how such objects can form from primordial gas polluted by a single supernova. In this ...paper, we present a shock-cloud model which simulates a supernova remnant interacting with a cloud in a metal-free environment at redshift z = 10. Pre-supernova conditions are considered, which include a multiphase neutral medium and H ii region. A small dense clump (n = 100 cm−3), located 40 pc from a 40 M⊙ metal-free star, embedded in an n = 10 cm−3 ambient cloud. The evolution of the supernova remnant and its subsequent interaction with the dense clump is examined. We include a comprehensive treatment of the non-equilibrium hydrogen and helium chemistry and associated radiative cooling that is occurring at all stages of the shock-cloud model, covering the temperature range 10-109 K. Deuterium chemistry and its associated cooling are not included because the UV radiation field produced by the relic H ii
region and supernova remnant is expected to suppress deuterium chemistry and cooling. We find a 103 times density enhancement of the clump (maximum density ≈78 000 cm−3) within this metal-free model. This is consistent with Galactic shock-cloud models considering solar metallicity gas with equilibrium cooling functions. Despite this strong compression, the cloud does not become gravitationally unstable. We find that the small cloud modelled here is destroyed for shock velocities ≳50 km s−1, and not significantly affected by shocks with velocity ≲30 km s−1. Rather specific conditions are required to make such a cloud collapse, and substantial further compression would be required to reduce the local Jeans mass to sub-solar values.
PDF
