Artists’ Labour Market and Gender: Evidence from German visual artists

Using comprehensive data from German visual artists, we provide strong empirical evidence of a gender gap in revenues. We find that female artists have significantly lower revenues from the art market and are about ten percentage points less likely to remain in the top category over three years. This gap persists in the most prominent art forms and is more pronounced for younger artists. Only 30 to 40 percent of these gaps can be explained by differences in observable characteristics. We also find differences in the networking behaviour of the artists of different genders: females are connecting more, whereas males tend to create tighter links, suggesting the importance of the latter for the art market.Series: Department of Economics Working Paper Serie

Tungsten isotopic compositions in stardust SiC grains from the Murchison meteorite: Constraints on the s-process in the Hf-Ta-W-Re-Os region

We report the first tungsten isotopic measurements in stardust silicon carbide (SiC) grains recovered from the Murchison carbonaceous chondrite. The isotopes 182W, 183W, 184W, 186W and 179Hf, 180Hf were measured on both an aggregate (KJB fraction) and single stardust SiC grains (LS+LU fraction) believed to have condensed in the outflows of low-mass carbon-rich asymptotic giant branch (AGB) stars with close-to-solar metallicity. The SiC aggregate shows small deviations from terrestrial (=solar) composition in the 182W/184W and 183W/184W ratios, with deficits in 182W and 183W with respect to 184W. The 186W/184W ratio, however, shows no apparent deviation from the solar value. Tungsten isotopic measurements in single mainstream stardust SiC grains revealed lower than solar 182W/184W, 183W/184W, and 186W/184W ratios. We have compared the SiC data with theoretical predictions of the evolution of W isotopic ratios in the envelopes of AGB stars. These ratios are affected by the slow neutron-capture process and match the SiC data regarding their 182W/184W, 183W/184W, and 179Hf/180Hf isotopic compositions, although a small adjustment in the s-process production of 183W is needed in order to have a better agreement between the SiC data and model predictions. The models cannot explain the 186W/184W ratios observed in the SiC grains, even when the current 185W neutron-capture cross section is increased by a factor of two. Further study is required to better assess how model uncertainties (e.g., the formation of the 13C neutron source, the mass-loss law, the modelling of the third dredge-up, and the efficiency of the 22Ne neutron source) may affect current s-process predictions.Comment: Accepted for Publication on The Astrophysical Journal 43 pages, 2 tables, 7 figure

Mitochondria and Energetic Depression in Cell Pathophysiology

Mitochondrial dysfunction is a hallmark of almost all diseases. Acquired or inherited mutations of the mitochondrial genome DNA may give rise to mitochondrial diseases. Another class of disorders, in which mitochondrial impairments are initiated by extramitochondrial factors, includes neurodegenerative diseases and syndromes resulting from typical pathological processes, such as hypoxia/ischemia, inflammation, intoxications, and carcinogenesis. Both classes of diseases lead to cellular energetic depression (CED), which is characterized by decreased cytosolic phosphorylation potential that suppresses the cell’s ability to do work and control the intracellular Ca2+ homeostasis and its redox state. If progressing, CED leads to cell death, whose type is linked to the functional status of the mitochondria. In the case of limited deterioration, when some amounts of ATP can still be generated due to oxidative phosphorylation (OXPHOS), mitochondria launch the apoptotic cell death program by release of cytochrome c. Following pronounced CED, cytoplasmic ATP levels fall below the thresholds required for processing the ATP-dependent apoptotic cascade and the cell dies from necrosis. Both types of death can be grouped together as a mitochondrial cell death (MCD). However, there exist multiple adaptive reactions aimed at protecting cells against CED. In this context, a metabolic shift characterized by suppression of OXPHOS combined with activation of aerobic glycolysis as the main pathway for ATP synthesis (Warburg effect) is of central importance. Whereas this type of adaptation is sufficiently effective to avoid CED and to control the cellular redox state, thereby ensuring the cell survival, it also favors the avoidance of apoptotic cell death. This scenario may underlie uncontrolled cellular proliferation and growth, eventually resulting in carcinogenesis

Cell-free systems based on CHO cell lysates: Optimization strategies, synthesis of "difficult-to-express" proteins and future perspectives

Nowadays, biotechnological processes play a pivotal role in target protein production. In this context, Chinese Hamster Ovary (CHO) cells are one of the most prominent cell lines for the expression of recombinant proteins and revealed as a safe host for nearly 40 years. Nevertheless, the major bottleneck of common in vivo protein expression platforms becomes obvious when looking at the production of so called “difficult-to-express” proteins. This class of proteins comprises in particular several ion channels and multipass membrane proteins as well as cytotoxic proteins. To enhance the production of “difficult-to-express” proteins, alternative technologies were developed, mainly based on translationally active cell lysates. These so called “cell-free” protein synthesis systems enable an efficient production of different classes of proteins. Eukaryotic cell-free systems harboring endogenous microsomal structures for the synthesis of functional membrane proteins and posttranslationally modified proteins are of particular interest for future applications. Therefore, we present current developments in cell-free protein synthesis based on translationally active CHO cell extracts, underlining the high potential of this platform. We present novel results highlighting the optimization of protein yields, the synthesis of various “difficult-to-express” proteins and the cotranslational incorporation of non-standard amino acids, which was exemplarily demonstrated by residue specific labeling of the glycoprotein Erythropoietin and the multimeric membrane protein KCSA

Linear DNA templates in cell-free protein synthesis based on CHO cell lysate.

<p>Linear IRES-luciferase and IRES-Mel-EPO templates tested during cell-free protein synthesis reactions in the presence of ¹⁴C leucine. Different concentrations of linear DNA product and T7 RNA polymerase (Pol) were added to the individual reactions. Protein yield was quantified by hot TCA precipitation followed by scintillation measurement. Error bars show standard deviations calculated from triplicates.</p

Quantitative analysis of cell-free protein synthesis: A comparison of different luciferase encoding vector backbones probed in CHO cell lysates.

<p><b>A.</b> Total protein yields were determined by incorporation of radioactive ¹⁴C leucine into <i>de novo</i> synthesized proteins followed by hot TCA precipitation and scintillation measurement. Yields of active luciferase were quantified by standard luciferase assay. <b>B.</b> Western blot analysis of cell-free produced luciferase using primary Anti-Luc antibody (concentration 1:1000) and secondary Anti-rabbit-HRP conjugate antibody (1:2000). Analysis of luciferase bands was performed by using ECL reagent and detection of corresponding light emission. Error bars show standard deviations calculated from triplicate analysis. NTC sample contains translation mixture without synthesized protein.</p

Residue specific fluorescence labeling of Mel-EPO and KCSA in cell-free systems based on translationally active CHO cell lysate.

<p>Cell-free protein synthesis based on CHO cell extracts was carried out in the presence of BODIPY-TMR-tRNA(Phe) to allow the fluorescence labeling of <i>de novo</i> synthesized Mel-EPO and KCSA. Produced glycosylated and transmembrane proteins were separated by SDS-PAGE. In-gel fluorescence was detected using a variable mode imager (Typhoon Trio Plus, GE Healthcare).</p

Protein yields using different luciferase encoding plasmids in cell-free synthesis based on CHO cell lysates.

<p>Protein yields using different luciferase encoding plasmids in cell-free synthesis based on CHO cell lysates.</p

Influence of PEG on protein production in cell-free systems based on translationally active CHO lysate.

<p>Two concentrations (1%, 2%) of different PEG molecules (3350, 5000, 20000) were analyzed in cell-free protein synthesis reactions using pIX3.0-CRPV(GCT)-eYFP plasmid template. Translation reactions without the addition of PEG but with supplementation of 3 U/μl (increased concentration) and 1 U/μl (standard concentration) T7 RNA polymerase served as control reactions <b><i>A</i></b>. Fluorescence signals of synthesized eYFP proteins were detected by fluorescence imaging on μ-Ibidi slides using the Typhoon Trio Plus Imager. <b><i>B</i></b>. Quantification of fluorescence signals was accomplished by using Image Quant TL Array analysis software. Error bars show standard deviations calculated from triplicate analysis.</p

Analysis of various types of proteins synthesized in CHO cell lysates.

<p>Standard cell-free protein synthesis was performed using pIX3.0-CPRV(GCT) plasmid backbones containing the different genes of interest. ¹⁴C leucine labeled proteins were precipitated in acetone, separated by SDS-PAGE and visualized by autoradiography. Produced proteins are listed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0163670#pone.0163670.t002" target="_blank">Table 2</a>. Arrows indicate the expected protein band of each individual protein. No template control (NTC) contains translation mixture without template to visualize the background translational activity of the CHO lysate.</p