Gastric Mammalian Target of Rapamycin Signaling Contributes to Inhibition of Ghrelin Expression Induced by Roux-En-Y Gastric Bypass

Background/Aims: Roux-en-Y Gastric Bypass, RYGB, is the most effective strategy to control body weight in morbid obesity. RYGB leads to rapid improvement of glycemic status and weight loss, which are largely attributed to the alteration of gastrointestinal hormones including ghrelin. The current study examined potential mechanisms of altered ghrelin synthesis after RYGB. Methods: Gastric mammalian target of rapamycin (mTOR) signaling, ghrelin synthesis and secretion were determined in lean or obese male mice with or without RYGB operation, as well as in obese patients pre- and post-RYGB surgery. Ghrelin expression and mTOR signaling were investigated by western blotting and immunohistochemistry. Ghrelin mRNA levels were detected by real-time PCR. Plasma ghrelin was measured by enzyme immunoassay. Results: mTOR activity in the gastric fundus was significantly lower than in the forestomachs. Both of them were decreased after 24h fasting. A significant negative correlation was found between gastric levels of phospho-S6 (phospho-S6 ribosomal protein) and proghrelin during changes of energy status. mTOR activity was activated, whereas ghrelin expression was inhibited by Roux-en-Y Gastric Bypass in both rodents and human beings. Increment of ghrelin synthesis and decline of mTOR signaling induced by rapamycin were significantly reversed by RYGB in both lean and obese mice. Administration of Ad-S6K1 (adenovirus-mediated p70 ribosomal protein subunit 6 kinase 1) from tail vein suppressed the expression of ghrelin in RYGB-operated mice relative to control animals. Conclusion: mTOR is therefore a gastric fuel sensor whose activity is linked to the regulation of ghrelin after Roux-en-Y Gastric Bypass

Ultrafast control of vortex microlasers

The development of classical and quantum information-processing technology calls for on-chip integrated sources of structured light. Although integrated vortex microlasers have been previously demonstrated, they remain static and possess relatively high lasing thresholds, making them unsuitable for high-speed optical communication and computing. We introduce perovskite-based vortex microlasers and demonstrate their application to ultrafast all-optical switching at room temperature. By exploiting both mode symmetry and far-field properties, we reveal that the vortex beam lasing can be switched to linearly polarized beam lasing, or vice versa, with switching times of 1 to 1.5 picoseconds and energy consumption that is orders of magnitude lower than in previously demonstrated all-optical switching. Our results provide an approach that breaks the long-standing trade-off between low energy consumption and high-speed nanophotonics, introducing vortex microlasers that are switchable at terahertz frequencies.This research was supported by the National Key Research and Development Program of China (grant no. SQ2018YFB220027), the Shenzhen Fundamental Research Fund (grant no. JCYJ20180507184613841), the Australian Research Council (grant no. DP200101168), and the National Science Foundation (grant no. PHY-1847240). The authors also acknowledge support from the Shenzhen Engineering Laboratory on Organic-Inorganic Perovskite Device

Near-Surface and High-Resolution Satellite Time Series for Detecting Crop Phenology

Detecting crop phenology with satellite time series is important to characterize agroecosystem energy-water-carbon fluxes, manage farming practices, and predict crop yields. Despite the advances in satellite-based crop phenological retrievals, interpreting those retrieval characteristics in the context of on-the-ground crop phenological events remains a long-standing hurdle. Over the recent years, the emergence of near-surface phenology cameras (e.g., PhenoCams), along with the satellite imagery of both high spatial and temporal resolutions (e.g., PlanetScope imagery), has largely facilitated direct comparisons of retrieved characteristics to visually observed crop stages for phenological interpretation and validation. The goal of this study is to systematically assess near-surface PhenoCams and high-resolution PlanetScope time series in reconciling sensor- and ground-based crop phenological characterizations. With two critical crop stages (i.e., crop emergence and maturity stages) as an example, we retrieved diverse phenological characteristics from both PhenoCam and PlanetScope imagery for a range of agricultural sites across the United States. The results showed that the curvature-based Greenup and Gu-based Upturn estimates showed good congruence with the visually observed crop emergence stage (RMSE about 1 week, bias about 0–9 days, and R square about 0.65–0.75). The threshold- and derivative-based End of greenness falling Season (i.e., EOS) estimates reconciled well with visual crop maturity observations (RMSE about 5–10 days, bias about 0–8 days, and R square about 0.6–0.75). The concordance among PlanetScope, PhenoCam, and visual phenology demonstrated the potential to interpret the fine-scale sensor-derived phenological characteristics in the context of physiologically well-characterized crop phenological events, which paved the way to develop formal protocols for bridging ground-satellite phenological characterization

Near-Surface and High-Resolution Satellite Time Series for Detecting Crop Phenology

Detecting crop phenology with satellite time series is important to characterize agroecosystem energy-water-carbon fluxes, manage farming practices, and predict crop yields. Despite the advances in satellite-based crop phenological retrievals, interpreting those retrieval characteristics in the context of on-the-ground crop phenological events remains a long-standing hurdle. Over the recent years, the emergence of near-surface phenology cameras (e.g., PhenoCams), along with the satellite imagery of both high spatial and temporal resolutions (e.g., PlanetScope imagery), has largely facilitated direct comparisons of retrieved characteristics to visually observed crop stages for phenological interpretation and validation. The goal of this study is to systematically assess near-surface PhenoCams and high-resolution PlanetScope time series in reconciling sensor- and ground-based crop phenological characterizations. With two critical crop stages (i.e., crop emergence and maturity stages) as an example, we retrieved diverse phenological characteristics from both PhenoCam and PlanetScope imagery for a range of agricultural sites across the United States. The results showed that the curvature-based Greenup and Gu-based Upturn estimates showed good congruence with the visually observed crop emergence stage (RMSE about 1 week, bias about 0–9 days, and R square about 0.65–0.75). The threshold- and derivative-based End of greenness falling Season (i.e., EOS) estimates reconciled well with visual crop maturity observations (RMSE about 5–10 days, bias about 0–8 days, and R square about 0.6–0.75). The concordance among PlanetScope, PhenoCam, and visual phenology demonstrated the potential to interpret the fine-scale sensor-derived phenological characteristics in the context of physiologically well-characterized crop phenological events, which paved the way to develop formal protocols for bridging ground-satellite phenological characterization

Simulation Study on Thermal Wake Characteristics of Underwater Vehicle under Rotary Motion

The high temperature cooling water generated by the power system of underwater vehicle is discharged through the discharge port and mixed with seawater to form a thermal wake, whose thermal characteristics can be easily detected by infrared submersible technology. In order to explore the characteristics of the thermal wake of the underwater vehicle when it rotates in fresh water, this paper uses the finite volume method to establish a three-dimensional scaled SUBOFF mathematical model, and then combines the overlapping grid technology to numerically simulate the rotation of the underwater vehicle in the background waters. The thermal wake experimental platform is established to verify the reliability of the numerical simulation method by comparing the direct flight experiment with the simulation results. The near-field cooling water trajectory and far-field wake spatial evolution behind the rotary body are analyzed, and the abnormal characteristics of water surface temperature are obtained. The results show that the thermal wakes on the turning side and the deviation side are greatly affected by the vortex caused by the body, and have great differences in morphology, motion trajectory and temperature characteristics. When the thermal wakes on both sides rise to the water surface, an arc-shaped water surface temperature anomaly area composed of two high-temperature hot spots is formed

Ghrelin and cell differentiation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71538/1/j.1745-7270.2008.00465.x.pd

Collision-Free Formation-Containment Tracking of Multi-USV Systems with Constrained Velocity and Driving Force

This paper studied the collision avoidance issue in the formation-containment tracking control of multi-USVs (unmanned surface vehicles) with constrained velocity and driving force. Specifically, based on a dual-layer control framework, it designed a multi-USV formation-containment tracking control strategy that accounts for constrained motion velocity and input driving force and validated the stability of this strategy using the Lyapunov method. Then, by utilizing zeroing control barrier function certificates, it considered collision avoidance among USVs with various roles as well as between each USV and static obstacles. A collision-free multi-USV formation-containment tracking control strategy considering constrained motion velocity and driving force was thus established, and its effectiveness was validated through the proposed simulation

mTOR-dependent Modulation of Gastric Nesfatin-1/NUCB2

Background: Nesfatin-1, an 82 amino acid peptide derived from the prohormone nucleobindin-2 (NUCB2), is a novel satiety hormone acting through a leptin-independent mechanism in the hypothalamus. The mechanisms by which production of nesfatin-1/NUCB2 is regulated remain unknown. Methods: Nesfatin-1/NUCB2 mRNA and immunoreactivity were examined in gastric tissue and Min-6 cells by RT-PCR and immunofluorescent staining or Western blotting. Results: Nesfatin-1/NUCB2 is co-localized with pS6K1, the downstream target of mammalian target of rapamycin (mTOR), in gastric X/A like cells. A parallel relationship between gastric mTOR signaling and nesfatin-1/NUCB2 was observed during changes in energy status. Both mTOR activity and gastric nesfatin-1/NUCB2 were down-regulated by fasting, and returned to basal levels with re-feeding. In high fat diet induced obese mice, gastric mTOR signaling and nesfatin-1/NUCB2 were increased. Inhibition of the gastric mTOR signaling by rapamycin attenuated the expression of gastric nesfatin-1/NUCB2 mRNA and protein in both lean and obese mice. Attenuation of mTOR activity by rapamycin or over-expression of TSC1 or TSC2 reduced the expression of nesfatin-1/NUCB2 in Min-6 cells, suggesting a direct effect of mTOR signaling. Conclusion: Gastric mTOR is a gastric energy sensor whose activity is linked to the regulation of gastric nesfatin-1/NUCB2. Copyright (C) 2012 S. Karger AG, Baselhttp://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000302752600018&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Cell BiologyPhysiologySCI(E)PubMed19ARTICLE3-4493-5002

The Role of Pancreatic Fatty Acid Synthesis in Islet Morphology and Function after Caloric Restriction or Roux-En-Y Gastric Bypass Surgery in Mice

Background: Both caloric restriction (CR) and Roux-en-Y gastric bypass (RYGB) are practical interventions for type 2 diabetes mellitus (T2DM), while the molecular mechanisms of CR and RYGB regarding glycemic control are still poorly understood. Here, we explore the effects and underlying mechanisms of CR and RYGB on β-cell area and function. Methods: Average islet size was measured by histological analysis. The pancreatic lipid content was detected by using a commercial lipid assay kit. The expression levels of lipogenic transcription factors and enzymes in mouse pancreas were determined by quantitative PCR, Western blot, and immunofluorescence. Results: CR decreased the mean size of islets and pancreatic insulin production in both regular diet-fed and high-fat diet-fed mice. Increased β-cell apoptosis was detected in the calorie-restricted mice. Interestingly, the lipogenic transcription factors and enzymes such as SREBP1c, PPARγ, FASN and ACC were upregulated in the pancreas after CR. In contrast to CR, RYGB decreased the apoptosis of β-cells and the expression of fatty acid synthase. Conclusions: Pancreatic fatty acid synthesis is critical to the β-cell function after CR and RYGB