311 research outputs found
Moduli Spaces of Parabolic Bundles over with Five Marked Points
This paper considers the moduli spaces (stacks) of parabolic bundles
(parabolic logarithmic flat bundles with given spectrum, parabolic regular
Higgs bundles) with rank and degree over with five
marked points. The foliation and stratification structures on these moduli
spaces (stacks) are investigated. In paricular, we confirm Simpson's conjecture
for moduli space of parabolic logarithmic flat bundles with certain non-special
weight system
Stark tuning of telecom single-photon emitters based on a single Er
The implementation of scalable quantum networks requires photons at the
telecom band and long-lived spin coherence. The single Er in solid-state
hosts is an important candidate that fulfills these critical requirements
simultaneously. However, to entangle distant Er ions through photonic
connections, the emission frequency of individual Er in solid-state
matrix must be the same, which is challenging because the emission frequency of
Er depends on its local environment. In this study, we propose and
experimentally demonstrate the Stark tuning of the emission frequency of a
single Er in a YSiO crystal by employing electrodes interfaced
with a silicon photonic crystal cavity. We obtain a Stark shift of 182.9
0.8 MHz which is approximately 27 times of the optical emission linewidth,
demonstrating the promising applications in tuning the emission frequency of
independent Er into the same spectral channels. Our results provide a
useful solution for the construction of scalable quantum networks based on
single Er and a universal tool for tuning the emission of individual
rare-earth ions
S-adenosylmethionine and methylthioadenosine are antiapoptotic in cultured rat hepatocytes but proapoptotic in human hepatoma cells
S-adenosylmethionine (AdoMet) is an essential compound in cellular transmethylation reactions and a precursor of polyamine and glutathione synthesis in the liver. In liver injury, the synthesis of AdoMet is impaired and its availability limited. AdoMet administration attenuates experimental liver damage, improves survival of alcoholic patients with cirrhosis, and prevents experimental hepatocarcinogenesis. Apoptosis contributes to different liver injuries, many of which are protected by AdoMet. The mechanism of AdoMet's hepatoprotective and chemopreventive effects are largely unknown. The effect of AdoMet on okadaic acid (OA)-induced apoptosis was evaluated using primary cultures of rat hepatocytes and human hepatoma cell lines. AdoMet protected rat hepatocytes from OA-induced apoptosis dose dependently. It attenuated mitochondrial cytochrome c release, caspase 3 activation, and poly(ADP-ribose) polymerase cleavage. These effects were independent from AdoMet-dependent glutathione synthesis, and mimicked by 5'-methylthioadenosine (MTA), which is derived from AdoMet. Interestingly, AdoMet and MTA did not protect HuH7 cells from OA-induced apoptosis; conversely both compounds behaved as proapoptotic agents. AdoMet's proapoptotic effect was dose dependent and observed also in HepG2 cells. In conclusion, AdoMet exerts opposing effects on apoptosis in normal versus transformed hepatocytes that could be mediated through its conversion to MTA. These effects may participate in the hepatoprotective and chemopreventive properties of this safe and well-tolerated drug
Evolutionary trajectories of snake genes and genomes revealed by comparative analyses of five-pacer viper
Snakes have numerous features distinctive from other tetrapods and a rich history of genome evolution that is still obscure. Here, we report the high-quality genome of the five-pacer viper, Deinagkistrodon acutus, and comparative analyses with other representative snake and lizard genomes. We map the evolutionary trajectories of transposable elements (TEs), developmental genes and sex chromosomes onto the snake phylogeny. TEs exhibit dynamic lineage-specific expansion, and many viper TEs show brain-specific gene expression along with their nearby genes. We detect signatures of adaptive evolution in olfactory, venom and thermal-sensing genes and also functional degeneration of genes associated with vision and hearing. Lineage-specific relaxation of functional constraints on respective Hox and Tbx limb-patterning genes supports fossil evidence for a successive loss of forelimbs then hindlimbs during snake evolution. Finally, we infer that the ZW sex chromosome pair had undergone at least three recombination suppression events in the ancestor of advanced snakes. These results altogether forge a framework for our deep understanding into snakes' history of molecular evolution
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Liver-heart crosstalk controls IL-22 activity in cardiac protection after myocardial infarction.
Interleukin (IL)-22 regulates tissue inflammation and repair. Here we report participation of the liver in IL-22-mediated cardiac repair after acute myocardial infarction (MI). Methods: We induced experimental MI in mice by ligation of the left ascending artery and evaluated the effect of IL-22 on post-MI cardiac function and ventricular remodeling. Results: Daily subcutaneous injection of 100 µg/kg mouse recombinant IL-22 for seven days attenuated adverse ventricular remodeling and improved cardiac function in mice at 28 days after left anterior descending coronary artery ligation-induced MI. Pharmacological inhibition of signal transducer and activator of transcription (STAT3) muted these IL-22 activities. While cardiomyocyte-selective depletion of STAT3 did not affect IL-22 activities in protecting post-MI cardiac injury, hepatocyte-specific depletion of STAT3 fully muted these IL-22 cardioprotective activities. Hepatocyte-derived fibroblast growth factor (FGF21) was markedly increased in a STAT3-dependent manner following IL-22 administration and accounted for the cardioprotective benefit of IL-22. Microarray analyses revealed that FGF21 controlled the expression of cardiomyocyte genes that are involved in cholesterol homeostasis, DNA repair, peroxisome, oxidative phosphorylation, glycolysis, apoptosis, and steroid responses, all of which are responsible for cardiomyocyte survival. Conclusions: Supplementation of IL-22 in the first week after acute MI effectively prevented left ventricular dysfunction and heart failure. This activity of IL-22 involved crosstalk between the liver and heart after demonstrating a role of the hepatic STAT3-FGF21 axis in IL-22-induced post-MI cardiac protection
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