Genome-Wide Identification, Sequence Variation, and Expression of the Glycerol-3-Phosphate Acyltransferase (GPAT) Gene Family in Gossypium

Cotton is an economically important crop grown for natural fiber and seed oil production. Cottonseed oil ranks third after soybean oil and colza oil in terms of edible oilseed tonnage worldwide. Glycerol-3-phosphate acyltransferase (GPAT) genes encode enzymes involved in triacylglycerol biosynthesis in plants. In the present study, 85 predicted GPAT genes were identified from the published genome data in Gossypium. Among them, 14, 16, 28, and 27 GPAT homologs were identified in G. raimondii, G. arboreum, G. hirsutum, and G. barbadense, respectively. Phylogenetic analysis revealed that a total of 108 GPAT genes from cotton, Arabidopsis and cacao could be classified into three groups. Furthermore, through comparison, the gene structure analyses indicated that GPAT genes from the same group were highly conserved between Arabidopsis and cotton. Segmental duplication could be the major driver for GPAT gene family expansion in the four cotton species above. Expression patterns of GhGPAT genes were diverse in different tissues. Most GhGPAT genes were induced or suppressed after salt or cold stress in Upland cotton. Eight GhGPAT genes were co-localized with oil and protein quantitative trait locus (QTL) regions. Thirty-two single nucleotide polymorphisms (SNPs) were detected from 12 GhGPAT genes, sixteen of which in nine GhGPAT genes were classified as synonymous, and sixteen SNPs in ten GhGPAT genes non-synonymous. Two SNP markers of the GhGPAT16 and GhGPAT26 genes were significantly correlated with cotton oil content in one of the three field tests. This study shed lights on the molecular evolutionary properties of GPAT genes in cotton, and provided reference for improvement of cotton response to abiotic stress and the genetic improvement of cotton oil content

Genome-Scale Analysis of the WRI-Like Family in Gossypium and Functional Characterization of GhWRI1a Controlling Triacylglycerol Content

Cotton (Gossypium spp.) is the most important natural fiber crop and the source of cottonseed oil, a basic by-product after ginning. AtWRI1 and its orthologs in several other crop species have been previously used to increase triacylglycerols in seeds and vegetative tissues. In the present study, we identified 22, 17, 9, and 11 WRI-like genes in G. hirsutum, G. barbadense, G. arboreum, and G. raimondii, respectively. This gene family was divided into four subgroups, and a more WRI2-like subfamily was identified compared with dicotyledonous Arabidopsis. An analysis of chromosomal distributions revealed that the 22 GhWRI genes were distributed on eight At and eight Dt subgenome chromosomes. Moreover, GhWRI1a was highly expressed in ovules 20–35 days after anthesis and was selected for further functional analysis. Ectopic expression of GhWRI1a rescued the seed phenotype of a wri1-7 mutant and increased the oil content of Arabidopsis seeds. Our comprehensive genome-wide analysis of the cotton WRI-like gene family lays a solid foundation for further studies

Transient Receptor Potential V Channels Are Essential for Glucose Sensing by Aldolase and AMPK

Fructose-1,6-bisphosphate (FBP) aldolase links sensing of declining glucose availability to AMPK activation via the lysosomal pathway. However, how aldolase transmits lack of occupancy by FBP to AMPK activation remains unclear. Here, we show that FBP-unoccupied aldolase interacts with and inhibits endoplasmic reticulum (ER)-localized transient receptor potential channel subfamily V, inhibiting calcium release in low glucose. The decrease of calcium at contact sites between ER and lysosome renders the inhibited TRPV accessible to bind the lysosomal v-ATPase that then recruits AXIN:LKB1 to activate AMPK independently of AMP. Genetic depletion of TRPVs blocks glucose starvation-induced AMPK activation in cells and liver of mice, and in nematodes, indicative of physical requirement of TRPVs. Pharmacological inhibition of TRPVs activates AMPK and elevates NAD(+) levels in aged muscles, rejuvenating the animals' running capacity. Our study elucidates that TRPVs relay the FBP-free status of aldolase to the reconfiguration of v-ATPase, leading to AMPK activation in low glucose

Fructose-1,6-bisphosphate and aldolase mediate glucose sensing by AMPK

葡萄糖是生物中最基本、最主要的营养物质，它不仅是机体能量的主要来源，也是生物质合成的主要原料。因此，葡萄糖的水平对于生物体是极其重要的。然而，在生活中，体内葡萄糖水平的波动是十分常见的，这是因为我们不可能每时每刻都在摄入葡萄糖：睡一大觉、剧烈运动几个小时或者太忙了没时间吃饭，都会引起葡萄糖水平的显著下降。这时，机体能够触发一套有效的过程应对这类“不利情况”，其中最为关键的就是激活“代谢的核心调节”——AMPK。在葡萄糖水平下降时，被激活的AMPK能够迅速启动脂肪、蛋白质的分解代谢，关闭它们的合成代谢，从而起到维持机体的能量和物质代谢的平衡，弥补机体因葡萄糖不足引起的胁迫压力。那么，机体如何感受葡萄糖水平下降，并“传递”给AMPK使其激活呢？林圣彩教授课题组的这项研究正是发现了生理状态下机体感受葡萄糖水平的机制。通过研究他们发现，无论在不含葡萄糖的细胞培养条件下，还是在饥饿的低血糖的动物体内，都不能观测到AMP水平的上升，这充分说明了机体有一套尚不为人知的、独立于AMP的感应葡萄糖水平的机制。在进一步的研究中他们揭示了这一完整过程：葡萄糖水平下降将引起的葡萄糖代谢中间物——果糖1,6-二磷酸（fructose-1,6-bisphosphate）水平的下降，该过程进一步地被糖酵解通路上的代谢酶——醛缩酶（aldolase）感应，因为醛缩酶正是将含有6个碳原子的果糖1,6-二磷酸裂解成三碳糖的酶，一旦醛缩酶“吃不到”由葡萄糖衍生的果糖1,6-二磷酸，它便“翻脸”，传递给也正是林圣彩教授课题组先前发现的溶酶体途径进而激活AMPK。该过程完全不涉及AMP水平，即能量水平的变化，是一条全新的、完全建立在实际的生理情况上的通路。林圣彩教授进一步地把葡萄糖水平总结为一种“状态信号”，以区别于传统的“能量信号”。据悉，该葡萄糖感知通路的发现对开发用于治疗肥胖症，乃至延长寿命的药物具有深远的意义。【Abstract】The major energy source for most cells is glucose, from which ATP is generated via glycolysis and/or oxidative metabolism. Glucose deprivation activates AMP-activated protein kinase (AMPK)1, but it is unclear whether this activation occurs solely via changes in AMP or ADP, the classical activators of AMPK2, 3, 4, 5. Here, we describe an AMP/ADP-independent mechanism that triggers AMPK activation by sensing the absence of fructose-1,6-bisphosphate (FBP), with AMPK being progressively activated as extracellular glucose and intracellular FBP decrease. When unoccupied by FBP, aldolases promote the formation of a lysosomal complex containing at least v-ATPase, ragulator, axin, liver kinase B1 (LKB1) and AMPK, which has previously been shown to be required for AMPK activation6, 7. Knockdown of aldolases activates AMPK even in cells with abundant glucose, whereas the catalysis-defective D34S aldolase mutant, which still binds FBP, blocks AMPK activation. Cell-free reconstitution assays show that addition of FBP disrupts the association of axin and LKB1 with v-ATPase and ragulator. Importantly, in some cell types AMP/ATP and ADP/ATP ratios remain unchanged during acute glucose starvation, and intact AMP-binding sites on AMPK are not required for AMPK activation. These results establish that aldolase, as well as being a glycolytic enzyme, is a sensor of glucose availability that regulates AMPK.D.G.H. was supported by an Investigator Award from the Wellcome Trust (097726) and a Programme Grant from Cancer Research UK (C37030/A15101). S.-C.L. was supported by grants from the National Key Research and Development Project of China (2016YFA0502001) and the National Natural Science Foundation of China (#31430094, #31690101, #31571214, #31601152 and #J1310027)

Research on Multistage Rotor Assembly Optimization Methods for Aeroengine Based on the Genetic Algorithm

The coaxiality and unbalance are the two important indexes to evaluate the assembly quality of an aeroengine. It often needs to be tested and disassembled repeatedly to meet the double-objective requirements at the same time. Therefore, an intelligent assembly method is urgently needed to directly predict the optimal assembly orientations of the rotors at each stage to meet the double-objective requirements simultaneously. In this study, an assembly optimization method for the multistage rotor of an aeroengine is proposed based on the genetic algorithm. Firstly, a spatial location propagation model is developed to accurately predict the spatial position of each rotor after assembly. The alignment process of the assembly screw holes of the adjacent rotors is considered for the first time. Secondly, a new assembly optimization strategy is proposed to select different assembly data for the specific values of the coaxiality and unbalance, respectively. Finally, a double-objective fitness function is constructed based on the coaxiality and unbalance. The simulation and experimental results show that the assembly optimization method proposed in this study can be utilized to achieve synchronous optimization of the coaxiality and unbalance of an aeroengine during preassembly

Quantitative Expression of a Slight Deviation of the Impact Angle in a Collision Atomizer

In the processing of colliding atomizers, a small change in the inclination of each orifice will double the impact angle, seriously affecting its atomization performance. In this paper, the influence of slight impact angle deviation on atomization performance was studied in steps of 1°, quantitatively, for the first time. The cavitation effect of the flow field was combined with the shape and parameters of the atomization field. FLUENT was used to simulate the internal flow field, and an independently designed atomizer with transparent nozzles was used to detect the internal flow field in real time. The collision atomization experimental platform and the laser interference particle measurement platform were built independently, and the collision angle was adjusted through a high-precision rotating table to establish the relationship between collision-angle deviation (60° ± 5°) and the atomization field performance (Sauter mean diameter, atomization cone angle, and spatial distribution of droplets). The experimental results showed that under the same injection pressure, the increase in the collision angle led to an decrease in the Sauter mean diameter and an increase in the atomization cone angle. Taking 60° as the benchmark, the particle size distribution was concentrated at ~150 μm to 300 μm within the variation range of ±2°, and the peak positions were very similar

An Assembly Method for the Multistage Rotor of An Aero-Engine Based on the Dual Objective Synchronous Optimization for the Coaxality and Unbalance

The assembly quality of an aero-engine directly determines its stability in high-speed operation. The coaxiality and unbalance out of tolerance caused by improper assembly may give rise to complicated vibration faults. To meet the requirements of the dual objective and reduce the test cost, it is necessary to predict the optimal assembly angles of the rotors at each stage during pre-assembly. In this study, we proposed an assembly optimization method for a multistage rotor of an aero-engine. Firstly, we developed a coordinate transmission model to calculate the coordinates of any point in the rotors at each stage during the assembly processes of a multistage rotor. Moreover, we proposed two different pieces of assembly optimization data for the coaxiality and unbalance, and established a dual objective evaluation function of that. Furthermore, we used the genetic algorithm to solve the optimal assembly angles of the rotors at each stage. Finally, the Monte Carlo simulation technique was used to investigate the effects of the geometric measured errors of each rotor on the proposed genetic algorithm. The simulation results show that the process of the dual objective optimization had good convergence, and the obtained optimal assembly angles of each rotor were not affected by the geometric measured errors. In addition, the dual objective optimization can ensure that both the coaxiality and unbalance can approach their respective optimal values to the most extent, and the experimental results also verified this conclusion. Therefore, the assembly optimization method proposed in this study can be used to guide the assembly processes of the multistage rotor of an aero-engine to achieve synchronous optimization for the coaxality and unbalance

An Unbalance Optimization Method for a Multi-Stage Rotor Based on an Assembly Error Propagation Model

For the assembly of a multi-stage rotor, such as an aero-engine or gas turbine, the parts need to be assembled optimally to avoid excessive unbalance. We propose a method to optimize the unbalance of a multi-stage rotor during assembly. First, we developed an assembly error propagation model for a multi-stage rotor. The alignment process and distribution of the screw holes of the adjacent rotors was considered for the first time. Secondly, we propose a new assembly datum for unbalance optimization to ensure consistency with the actual conditions of a dynamic balance test. Finally, the unbalance optimization of a multi-stage rotor was achieved using a genetic algorithm, and the corresponding optimal assembly orientations of rotors at different stages were also identified. The results of the simulations showed that the assembly error propagation model had high accuracy and that the genetic optimization process had good convergence. The effect of unbalance optimization was also proven with experiments

Nonlinearity Correction in OFDR System Using a Zero-Crossing Detection-Based Clock and Self-Reference

Tuning nonlinearity of the laser is the main source of deterioration of the spatial resolution in optical frequency-domain reflectometry (OFDR) system. In this paper, we develop methods for tuning nonlinearity correction in an OFDR system from the aspect of data acquisition and post-processing. An external clock based on a zero-crossing detection is researched and implemented using a customized circuit. Equal-spacing frequency sampling is, therefore, achieved in real-time. The zero-crossing detection for the beating frequency of 20 MHz is achieved. The maximum sensing distance can reach the same length of the auxiliary interferometer. Moreover, a nonlinearity correction method based on the self-reference method is proposed. The auxiliary interferometer is no longer necessary in this scheme. The tuning information of the laser is extracted by a strong reflectivity point at the end of the measured fiber. The tuning information is then used to resample the raw signal, and the nonlinearity correction can be achieved. The spatial resolution test and the distributed strain measurement test were both performed based on this nonlinearity correction method. The results validated the feasibility of the proposed method. This method reduces the hardware and data burden for the system and has potential value for system integration and miniaturization

A Balancing Method for Multi-Disc Flexible Rotors without Trial Weights

Rotor dynamic balancing is a classical problem. Traditional balancing methods such as the influence coefficient method and the modal balancing method, have low balancing efficiency because they need to run many times to add trial weights. Although the model-based balancing method improves the balancing efficiency, it cannot accurately identify the position, amplitude and phase of each unbalance fault for rotors with multi-disc structures, so it is difficult to apply it to actual balancing. To solve the above problems, based on the traditional modal balancing theory, this paper deduces that the continuous and isolated unbalance in the rotor-bearing system can be represented by isolated unbalance on several balancing planes approximately. The model-based method is used to identify the above-mentioned equivalent isolated unbalances, and then the corrected mass is added to the balancing planes so as to complete the balance of multiple flexible rotor without trial weights. Considering the practical situation, the proposed balancing method includes two steps: low-speed balancing and high-speed balancing. The proposed balancing method is verified using three and four-disc rotors. The simulation results show that the balancing method can effectively reduce the vibration of the flexible rotor after low-speed and high-speed balancing, and the amplitude at the measurement point is reduced by 79.74~97.60%, respectively