Mechanistic understanding of \u3ci\u3eN\u3c/i\u3e-glycosylation in Ebola virus glycoprotein maturation and function

The Ebola virus (EBOV) trimeric envelope glycoprotein (GP) precursors are cleaved into the receptor-binding GP1 and the fusion-mediating GP2 subunits and incorporated into virions to initiate infection. GP1 and GP2 form heterodimers that have 15 or two N-glycosylation sites (NGSs), respectively. Here we investigated the mechanism of how N-glycosylation contributes to GP expression, maturation, and function. As reported before, we found that, although GP1 NGSs are not critical, the two GP2 NGSs, Asn563 and Asn618, are essential for GP function. Further analysis uncovered that Asn563 and Asn618 regulate GP processing, demannosylation, oligomerization, and conformation. Consequently, these two NGSs are required for GP incorporation into EBOV-like particles and HIV type 1 (HIV-1) pseudovirions and determine viral transduction efficiency. Using CRISPR/Cas9 technology, we knocked out the two classical endoplasmic reticulum chaperones calnexin (CNX) and/or calreticulin (CRT) and found that bothCNXand CRT increase GP expression. Nevertheless, NGSs are not required for the GP interaction with CNX or CRT. Together, we conclude that, although Asn563 and Asn618 are not required for EBOV GP expression, they synergistically regulate its maturation, which determines its functionality

Activin A and BMP4 Signaling Expands Potency of Mouse Embryonic Stem Cells in Serum-Free Media.

Inhibitors of Mek1/2 and Gsk3β, known as 2i, and, together with leukemia inhibitory factor, enhance the derivation of embryonic stem cells (ESCs) and promote ground-state pluripotency (2i/L-ESCs). However, recent reports show that prolonged Mek1/2 suppression impairs developmental potential of ESCs, and is rescued by serum (S/L-ESCs). Here, we show that culturing ESCs in Activin A and BMP4, and in the absence of MEK1/2 inhibitor (ABC/L medium), establishes advanced stem cells derived from ESCs (esASCs). We demonstrate that esASCs contributed to germline lineages, full-term chimeras and generated esASC-derived mice by tetraploid complementation. We show that, in contrast to 2i/L-ESCs, esASCs display distinct molecular signatures and a stable hypermethylated epigenome, which is reversible and similar to serum-cultured ESCs. Importantly, we also derived novel ASCs (blASCs) from blastocysts in ABC/L medium. Our results provide insights into the derivation of novel ESCs with DNA hypermethylation from blastocysts in chemically defined medium

DNMTs Play an Important Role in Maintaining the Pluripotency of Leukemia Inhibitory Factor-Dependent Embryonic Stem Cells.

Naive pluripotency can be maintained in medium with two inhibitors plus leukemia inhibitory factor (2i/LIF) supplementation, which primarily affects canonical WNT, FGF/ERK, and JAK/STAT3 signaling. However, whether one of these three supplements alone is sufficient to maintain naive self-renewal remains unclear. Here we show that LIF alone in medium is sufficient for adaptation of 2i/L-ESCs to embryonic stem cells (ESCs) in a hypermethylated state (L-ESCs). Global transcriptomic analysis shows that L-ESCs are close to 2i/L-ESCs and in a stable state between naive and primed pluripotency. Notably, our results demonstrate that DNA methyltransferases (DNMTs) play an important role in LIF-dependent mouse ESC adaptation and self-renewal. LIF-dependent ESC adaptation efficiency is significantly increased in serum treatment and reduced in Dnmt3a or Dnmt3l knockout ESCs. Importantly, unlike epiblast stem cells, L-ESCs contribute to somatic tissues and germ cells in chimeras. L-ESCs cultured under such simple conditions as in this study would provide a more conducive platform to clarify the molecular mechanism of ESCs in in vitro culture

Testicular Characteristics and the Block to Spermatogenesis in Mature Hinny

Most hinnies (female donkey×male horse) and mules (female horse×male donkey) are sterile with few reports of equine fertile hybrids. The main cause of this sterility is thought to be a meiotic block to spermatogenesis and oogenesis. This study compared the developmental features of the testes and a histological analyses of spermatogenesis in a male hinny with those of a normal, fertile stallion and Jack donkey. Hinny testes showed a thicker tunica albuginea, fewer blood vessels and more connective tissue in the testis parenchyma than those of the stallion and Jack donkey. Although the mean number of seminiferous tubules was significantly higher in stallion and hinny than Jack donkey (p<0.01), the mean proportion of seminiferous tubules was lower in the hinny (p<0.01) which resulted in a smaller diameter of seminiferous tubules. The mean number of spermatogonia and spermatocytes per unit area were significantly lower in hinny testis (p<0.01) and no spermatids or mature spermatozoa cells were found during immunofluorescent analyses. These results indicated that defects in seminiferous tubule development and structure occur in the testis of hinnies. Furthermore, most spermatogonia and spermatocytes cease development in synapsis during mid-meiosis of spermatocytes, which results in a block to spermatogenesis that prevents the formation of spermatids and matured spermatozoa during meiosis in male hinnies

Experimental and analytical study on heating and road performance of asphalt mixture with silicon carbide and ferroferric oxide composite structure layer

Microwave heating is currently considered to be the most promising clean energy technology for asphalt pavement deicing. In order to improve the heating efficiency of pavement surface, a 10 mm silicon carbide (SiC) and ferroferric oxide (Fe3O4) composite structure layer (CSL) was designed on the pavement surface. The surface heating efficiency and road performance of asphalt mixture with CSL were investigated by laboratory experiments, and the distribution of electromagnetic and temperature fields were analyzed by numerical simulations. The experimental results show that the surface temperature of asphalt mixture with CSL was 1.64 and 1.36 times higher than that of the ordinary asphalt mixture and the asphalt mixture with SiC and Fe3O4 composite material, and it remained stable before and after repeated heating and water bath, with a difference of only 1 ℃∼1.7 ℃. The asphalt mixture with CSL had good road performance. The Marshall stability, residual stability and interlayer shear strength could remain above 10 kN, 92% and 4 MPa after repeated heating. The numerical simulation results show that the asphalt mixture mixed with microwave absorbing materials produced a larger electromagnetic field intensity. The heat of asphalt mixture with CSL was mainly concentrated on the road surface because the absorbing material was concentrated on the road surface. In contrast, because there was no difference in microwave absorption capacity throughout the asphalt mixture with SiC and Fe3O4 composite material, the heat distribution was mainly influenced by the electromagnetic field intensity. In general, asphalt mixture with CSL has higher surface heating efficiency and road performance

Optimization of Tensile Shear Strength of Linear Mechanically Welded Outer-to-Inner Flattened Moso Bamboo (Phyllostachys pubescens)

International audienceMechanical welding technology has been widely employed in the making of bonding joints with wood. Moso bamboo, a lignocellulosic biomaterial, can also be bonded using mechanical welding technology. The surface response methodology was used to define welding parameters yielding optimal joint strength. In the range of this experiment, it was found that the vibration amplitude and the welding pressure both had a significant influence on the performance of the joint, while the welding time did not. The quadratic model was able to significantly fit the actual results and could be used to determine and optimize the bonding strength

Silver-Catalyzed Cyclopropanation of Alkenes Using N-Nosylhydrazones as Diazo Surrogates

An efficient silver-catalyzed [2 + 1] cyclopropanation of sterically hindered internal alkenes with diazo compounds in which room- temperature-decomposable N-nosylhydrazones are used as diazo surro- gates is reported. The unexpected unique catalytic activity of silver was ascribed to its dual role as a Lewis acid activating alkene substrates and as a transition metal forming silver carbenoids. A wide range of internal alkenes, including challenging diarylethenes, were suitable for this protocol, thereby affording a variety of cyclopropanes with high efficiency in a stereoselective manner under mild conditions

Nurses’ Occupational Stress and Presenteeism: The Mediating Role of Public Service Motivation and the Moderating Role of Health

Presenteeism not only poses an economic cost to organizations but also generates reduced work efficiency and quality. The purpose of this study was to examine the connections between occupational stress, public service motivation (PSM), health, and presenteeism. A total of 981 nurses from 109 public hospitals in Jilin Province in China were enrolled in our study. Model 5 in the PROCESS micro was employed in order to verify the mediating effect of PSM and the moderating effect of nurses’ health on the relationship between occupational stress and presenteeism, and simple slope analysis was used to further determine the moderating effect. Both challenge stress and hindrance stress had a positive impact on presenteeism among nurses. PSM is a mediating variable between occupational stress and presenteeism. Health moderates the path between challenge stress and presenteeism, with the association being significant for nurses with low levels of health. Future policy making should focus on preventing presenteeism by reducing excessive stress, enhancing PSM, and improving nurse health and wellness

Model-Based Off-Policy Deep Reinforcement Learning With Model-Embedding

Tan X, Qu C, Xiong J, Zhang J, Qiu X, Jin Y. Model-Based Off-Policy Deep Reinforcement Learning With Model-Embedding. IEEE Transactions on Emerging Topics in Computational Intelligence. 2024:1-13.Model-based reinforcement learning (MBRL) has shown its advantages in sample efficiency over model-free reinforcement learning (MFRL) by leveraging control-based domain knowledge. Despite the impressive results it achieves, MBRL is still outperformed by MFRL due to the lack of unlimited interactions with the environment. While imaginary data can be generated by imagining the trajectories of future states, a trade-off between the usage of data generation and the influence of model bias remains to be resolved. In this paper, we propose a simple and elegant off-policy model-based deep reinforcement learning algorithm with a model embedded in the framework of probabilistic reinforcement learning, called MEMB. To balance the sample-efficiency and model bias, we exploit both real and imaginary data in training. In particular, we embed the model in the policy update and learn value functions from the real data set. We also provide a theoretical analysis of MEMB with the Lipschitz continuity assumption on the model and policy, proving the reliability of the short-term imaginary rollout. Finally, we evaluate MEMB on several benchmarks and demonstrate that our algorithm can achieve state-of-the-art performance