Knockdown and overexpression of Unc-45b result in defective myofibril organization in skeletal muscles of zebrafish embryos

<p>Abstract</p> <p>Background</p> <p>Unc-45 is a myosin chaperone and a Hsp90 co-chaperone that plays a key role in muscle development. Genetic and biochemical studies in <it>C. elegans </it>have demonstrated that Unc-45 facilitates the process of myosin folding and assembly in body wall muscles. Loss or overexpression of Unc-45 in <it>C. elegans </it>results in defective myofibril organization. In the zebrafish <it>Danio rerio</it>, <it>unc-45b</it>, a homolog of <it>C. elegans unc-45</it>, is expressed in both skeletal and cardiac muscles. Earlier studies indicate that mutation or knockdown of <it>unc-45b </it>expression in zebrafish results in a phenotype characterized by a loss of both thick and thin filament organization in skeletal and cardiac muscle. The effects of <it>unc-45b </it>knockdown on other sarcomeric structures and the phenotype of Unc-45b overexpression, however, are poorly understood in vertebrates.</p> <p>Results</p> <p>Both knockdown and overexpression provide useful tools to study gene function during animal development. Using such methods, we characterized the role of Unc-45b in myofibril assembly of skeletal muscle in <it>Danio rerio</it>. We showed that, in addition to thick and thin filament defects, knockdown of <it>unc-45b </it>expression disrupted sarcomere organization in M-lines and Z-lines of skeletal muscles in zebrafish embryos. Western blotting analysis showed that myosin protein levels were significantly decreased in <it>unc-45b </it>knockdown embryos. Similarly, embryos overexpressing Unc-45b also exhibited severely disorganized myosin thick filaments. Disruption of thick filament organization by Unc-45b overexpression depends on the C-terminal UCS domain in Unc-45b required for interaction with myosin. Deletion of the C-terminal UCS domain abolished the disruptive activity of Unc-45b in myosin thick filament organization. In contrast, deletion of the N-terminal TPR domain required for binding with Hsp90α had no effect.</p> <p>Conclusion</p> <p>Collectively, these studies indicate that the expression levels of Unc-45b must be precisely regulated to ensure normal myofibril organization. Loss or overexpression of Unc-45b leads to defective myofibril organization.</p

PL - 027 Up-regulation of NRG1 improves cardiac repair in zebra fish and involved in the cardioprotective effects of exercise training in rats of myocardial infarction

Objective Myocardial infarction (MI) remains a leading cause of morbidity and mortality worldwide. Exercise training could improve cardiac function following MI. However, the mechanisms are still not well-known. Neuregulin 1 (NRG1)plays an important role in heart development and regeneration.In this study, we investigated the effect of NRG1 on cardiac regeneration in a zebrafish model, detected whether exercise could improve cardiac function through regulating NRG1 expression in infarcted heart and explore the possible role of up-regulation of NRG1 in skeletal muscle play in the cardioprotective effects in rats with MI. Methods Transgenic zebrafish line, cmlc2:CreERandβ-act2:BSNrg1,wereusedto study the effect of NRG1 on heart growth and regeneration after injury. PCNA was detected by immunofluorescence staining andmRNAexpression of gata4, nkx2.5, tbx5, smyd1b, hsp90α and murf were tested by RT-PCR.Sprague-Dawley rats were used to establish MI model and underwent fourweeks of exercise training (ET) or pAAV-{dMCK promoter}rNRG1-eGFP intervention.AG1478 was used asan inhibitor of NRG1/ErbBs signaling pathway. Cardiac function and structure,cardiomyocyte proliferation and NRG1 expression were detected in the heart or skeletal. Results Cardiac-specific overexpression of NRG1 induced cardiac hypertrophy and cardiomyocyte proliferation, regulated the mRNA expression of gata4, nkx2.5, tbx5, smyd1b, hsp90α andmurf in uninjuriedzebrafish, and promote cardiac repair and regeneration after injury in the zebrafish.Exercise activated NRG1/ErbBs signaling pathway, improved cardiac remodeling and heart function, enhanced cardiomyocyte proliferation, reduced cardiomyocyte apoptosis, ROS level and MuRF1 protein expression in rats with MI. BlockingErbB signaling attenuated the ET-induced cardioprotection effects in rat with MI.up-regulation of NRG1 expression in skeletal muscle could increase the protein level of NRG1 in serum and infarcted heart, improve cardiomyocyte proliferation and reduce the level of cardiac fibrosis, finally promote cardiac function. Conclusions Up-regulation of NRG1 expression in the heart or skeletal musclemay be one of the underlying mechanisms of thebeneficial effects of exercise training following MI

Removal of Mercury(II) from Aqueous Solutions by Adsorption on Poly(1-amino-5-chloroanthraquinone) Nanofibrils: Equilibrium, Kinetics, and Mechanism Studies

Poly(1-amino-5-chloroanthraquinone) (PACA) nanofibrils were applied as novel nanoadsorbents for highly toxic mercury removal from aqueous solutions. A series of batch adsorption experiments were conducted to study the effect of adsorbent dose, pH, contact time, and metal concentration on Hg(II) uptake by PACA nanofibrils. Kinetic data indicated that the adsorption process of PACA nanofibrils for Hg(II) achieved equilibrium within 2 h following a pseudo-second-order rate equation. The adsorption mechanism of PACA nanofibrils for Hg(II) was investigated by Fourier transform-infrared (FT-IR) spectra and X-ray photoelectron spectroscopy (XPS) analyses. The adsorption isotherm of Hg(II) fitted well the Langmuir model, exhibiting superb adsorption capacity of 3.846 mmol of metal per gram of adsorbent. Lastly, we found out that the as-synthesized PACA nanofibrils are efficient in Hg(II) removal from real wastewater. Furthermore, five consecutive adsorption-desorption cycles demonstrated that the PACA nanofibrils were suitable for repeated use without considerable changes in the adsorption capacity

Removal of Mercury(II) from Aqueous Solutions by Adsorption on Poly(1-amino-5-chloroanthraquinone) Nanofibrils: Equilibrium, Kinetics, and Mechanism Studies

Poly(1-amino-5-chloroanthraquinone) (PACA) nanofibrils were applied as novel nanoadsorbents for highly toxic mercury removal from aqueous solutions. A series of batch adsorption experiments were conducted to study the effect of adsorbent dose, pH, contact time, and metal concentration on Hg(II) uptake by PACA nanofibrils. Kinetic data indicated that the adsorption process of PACA nanofibrils for Hg(II) achieved equilibrium within 2 h following a pseudo-second-order rate equation. The adsorption mechanism of PACA nanofibrils for Hg(II) was investigated by Fourier transform-infrared (FT-IR) spectra and X-ray photoelectron spectroscopy (XPS) analyses. The adsorption isotherm of Hg(II) fitted well the Langmuir model, exhibiting superb adsorption capacity of 3.846 mmol of metal per gram of adsorbent. Lastly, we found out that the as-synthesized PACA nanofibrils are efficient in Hg(II) removal from real wastewater. Furthermore, five consecutive adsorption-desorption cycles demonstrated that the PACA nanofibrils were suitable for repeated use without considerable changes in the adsorption capacity

Size-segregated particle number and mass concentrations from different emission sources in urban Beijing

Although secondary particulate matter is reported to be the main contributor of PM2.5 during haze in Chinese megacities, primary particle emissions also affect particle concentrations. In order to improve estimates of the contribution of primary sources to the particle number and mass concentrations, we performed source apportionment analyses using both chemical fingerprints and particle size distributions measured at the same site in urban Beijing from April to July 2018. Both methods resolved factors related to primary emissions, including vehicular emissions and cooking emissions, which together make up 76% and 24% of total particle number and organic aerosol (OA) mass, respectively. Similar source types, including particles related to vehicular emissions (1.6 +/- 1.1 mu gm(-3); 2.4 +/- 1.8 x 10(3) cm(-3) and 5.5 +/- 2.8 x 10(3) cm(-3) for two traffic-related components), cooking emissions (2.6 +/- 1.9 mu gm(-3) and 5.5 +/- 3.3 x 10(3) cm(-3)) and secondary aerosols (51 +/- 41 mu gm(-3) and 4.2 +/- 3.0 x 10(3) cm(-3)), were resolved by both methods. Converted mass concentrations from particle size distributions components were comparable with those from chemical fingerprints. Size distribution source apportionment separated vehicular emissions into a component with a mode diameter of 20 nm ("traffic-ultrafine") and a component with a mode diameter of 100 nm ("traffic-fine"). Consistent with similar day- and nighttime diesel vehicle PM2.5 emissions estimated for the Beijing area, traffic-fine particles, hydrocarbon-like OA (HOA, traffic-related factor resulting from source apportionment using chemical fingerprints) and black carbon (BC) showed similar diurnal patterns, with higher concentrations during the night and morning than during the afternoon when the boundary layer is higher. Traffic-ultrafine particles showed the highest concentrations during the rush-hour period, suggesting a prominent role of local gasoline vehicle emissions. In the absence of new particle formation, our re-sults show that vehicular-related emissions (14% and 30% for ultrafine and fine particles, respectively) and cooking-activity-related emissions (32 %) dominate the particle number concentration, while secondary particulate matter (over 80 %) governs PM2.5 mass during the non-heating season in Beijing.Peer reviewe

Unprecedented Ambient Sulfur Trioxide (SO3) Detection : Possible Formation Mechanism and Atmospheric Implications

Sulfur trioxide (SO3) is a crucial compound for atmospheric sulfuric acid (H2SO4) formation, acid rain formation, and other atmospheric physicochemical processes. During the daytime, SO3 is mainly produced from the photo-oxidation of SO2 by OH radicals. However, the sources of SO3 during the early morning and night, when OH radicals are scarce, are not fully understood. We report results from two field measurements in urban Beijing during winter and summer 2019, using a nitrate-CI-APi-LTOF (chemical ionization-atmospheric pressure interface-long-time-offlight) mass spectrometer to detect atmospheric SO3 and H2SO4. Our results show the level of SO3 was higher during the winter than during the summer, with high SO3 levels observed especially during the early morning (similar to 05:00 to similar to 08:30) and night (similar to 18:00 to similar to 05:00 the next day). On the basis of analysis of SO2, NOx, black carbon, traffic flow, and atmospheric ions, we suggest SO3 could be formed from the catalytic oxidation of SO2 on the surface of traffic-related black carbon. This previously unidentified SO3 source results in significant H2SO4 formation in the early morning and thus promotes sub-2.5 nm particle formation. These findings will help in understanding urban SO3 and formulating policies to mitigate secondary particle formation in Chinese megacities.Peer reviewe

The effect of COVID-19 restrictions on atmospheric new particle formation in Beijing

During the COVID-19 lockdown, the dramatic reduction of anthropogenic emissions provided a unique opportunity to investigate the effects of reduced anthropogenic activity and primary emissions on atmospheric chemical processes and the consequent formation of secondary pollutants. Here, we utilize comprehensive observations to examine the response of atmospheric new particle formation (NPF) to the changes in the atmospheric chemical cocktail. We find that the main clustering process was unaffected by the drastically reduced traffic emissions, and the formation rate of 1.5 nm particles remained unaltered. However, particle survival probability was enhanced due to an increased particle growth rate (GR) during the lockdown period, explaining the enhanced NPF activity in earlier studies. For GR at 1.5-3 nm, sulfuric acid (SA) was the main contributor at high temperatures, whilst there were unaccounted contributing vapors at low temperatures. For GR at 3-7 and 7-15 nm, oxygenated organic molecules (OOMs) played a major role. Surprisingly, OOM composition and volatility were insensitive to the large change of atmospheric NOx concentration; instead the associated high particle growth rates and high OOM concentration during the lockdown period were mostly caused by the enhanced atmospheric oxidative capacity. Overall, our findings suggest a limited role of traffic emissions in NPF.Peer reviewe

A Single-Loop Optimization Method for Reliability Analysis with Second Order Uncertainty

Reliability analysis may involve random variables and interval variables. In addition, some of the random variables may have interval distribution parameters owing to limited information. This kind of uncertainty is called second order uncertainty. This article develops an efficient reliability method for problems involving the three aforementioned types of uncertain input variables. The analysis produces the maximum and minimum reliability and is computationally demanding because two loops are needed: a reliability analysis loop with respect to random variables and an interval analysis loop for extreme responses with respect to interval variables. The first order reliability method and nonlinear optimization are used for the two loops, respectively. For computational efficiency, the two loops are combined into a single loop by treating the Karush-Kuhn-Tucker (KKT) optimal conditions of the interval analysis as constraints. Three examples are presented to demonstrate the proposed method