Cellular and Molecular Mechanisms of Hepatic Fibrosis

The occurrence of hepatic fibrosis is a multi-factor involved process. The key is the activation of hepatic stellate cells (HSC). Synthesis of extracellular matrix in the liver cells increases while degradation decreases. This paper reviews the tissue factors and the mechanism closely related to the forming of hepatic fibrosis

Biology, physiology and gene expression of grasshopper Oedaleus asiaticus exposed to diet stress from plant secondary compounds

This study was supported by the National Natural Science Foundation of China, 31672485, the Earmarked Fund for China Agriculture Research System, CARS-35-07, and the Innovation Project of Chinese Academy of Agricultural Science.We studied the role of plant primary and secondary metabolites in mediating plant-insect interactions by conducting a no-choice single-plant species field experiment to compare the suitability, enzyme activities, and gene expression of Oedaleus asiaticus grasshoppers feeding on four host and non-host plants with different chemical traits. O. asiaticus growth showed a positive relationship to food nutrition content and a negative relationship to secondary compounds content. Grasshopper amylase, chymotrypsin, and lipase activities were positively related to food starch, crude protein, and lipid content, respectively. Activity of cytochrome P450s, glutathione-S-transferase, and carboxylesterase were positively related to levels of secondary plant compounds. Gene expression of UDP-glucuronosyltransferase 2C1, cytochrome P450 6K1 were also positively related to secondary compounds content in the diet. Grasshoppers feeding on Artemisia frigida, a species with low nutrient content and a high level of secondary compounds, had reduced growth and digestive enzyme activity. They also had higher detoxification enzyme activity and gene expression compared to grasshoppers feeding on the grasses Cleistogenes squarrosa, Leymus chinensis, or Stipa krylovii. These results illustrated Oedaleus asiaticus adaptive responses to diet stress resulting from toxic chemicals, and support the hypothesis that nutritious food benefits insect growth, but plant secondary compounds are detrimental for insect growth.Publisher PDFPeer reviewe

PREDICTION ON METER FACTOR OF THE TURBINE FLOW METER WITH UNSTEADY NUMERICAL SIMULATION

ABSTRACT The turbine flow meter is widely used in the flow rate measuring for its high accuracy and good repeatability. The flow rate will be calculated based on its meter factor, which is the most important factor of the turbine flow meter. The meter factor means pulses or revolution of the impeller per unit volume, and it can only be got from the calibration experiment. At the given flow rate, the driving torque on the impeller is equal to the drag torque, as many paper have pointed out. Based on the torque balancing equations, unsteady numerical simulation is carried out with RNG turbulence model and UDFs (User Defined Functions) in Fluent Code. The meter factor under different flow rate is calculated with the unsteady simulation. The prediction results based on the numerical simulation showed the same trends as the calibration experiment. At the most flow rate, the meter factor keeps constant, but at the lower flow rate, the meter factor higher than the constant. Because of neglecting the bearing friction drag in the process, the meter factor by numerical simulation is larger than experimen

Quantitative analysis of diet structure by real-time PCR, reveals different feeding patterns by two dominant grasshopper species

This study was supported by the National Natural Science Foundation of China, 31471823, the Earmarked Fund for China Agriculture Research System, CARS-35-07, and the Innovation Project of Chinese Academy of Agricultural Science.Studies on grasshopper diets have historically employed a range of methodologies, each with certain advantages and disadvantages. For example, some methodologies are qualitative instead of quantitative. Others require long experimental periods or examine population-level effects, only. In this study, we used real-time PCR to examine diets of individual grasshoppers. The method has the advantage of being both fast and quantitative. Using two grasshopper species, Oedaleus asiaticus and Dasyhippus barbipes, we designed ITS primer sequences for their three main host plants, Stipa krylovii, Leymus chinensis and Cleistogenes squarrosa and used real-time PCR method to test diet structure both qualitatively and quantitatively. The lowest detection efficiency of the three grass species was ~80% with a strong correlation between actual and PCR-measured food intake. We found that Oedaleus asiaticus maintained an unchanged diet structure across grasslands with different grass communities. By comparison, Dasyhippus barbipes changed its diet structure. These results revealed why O. asiaticus distribution is mainly confined to Stipa-dominated grassland, and D. barbipes is more widely distributed across Inner Mongolia. Overall, real-time PCR was shown to be a useful tool for investigating grasshopper diets, which in turn offers some insight into grasshopper distributions and improved pest management.Publisher PDFPeer reviewe

Molecular ecological basis of grasshopper (Oedaleus asiaticus) phenotypic plasticity under environmental selection

This research was supported by the Special Fund for Agro-scientific Research in the Public Interest (201003079), China, the earmarked fund for the China Agriculture Research System (CARS-35-07 and CARS-34-7B), the Innovation Project of the Chinese Academy of Agricultural Sciences, National Nature Science Foundation of China (31672485), and the CSC Scholarship from the China Scholarship Council. The transcriptome data of O. asiaticus females was submitted to SRA database in NCBI and have been released (ID: SRP059063).While ecological adaptation in insects can be reflected by plasticity of phenotype, determining the causes and molecular mechanisms for phenotypic plasticity (PP) remains a crucial and still difficult question in ecology, especially where control of insect pests is involved. Oedaleus asiaticus is one of the most dominant pests in the Inner Mongolia steppe and represents an excellent system to study phenotypic plasticity. To better understand ecological factors affecting grasshopper phenotypic plasticity and its molecular control, we conducted a full transcriptional screening of O. asiaticus grasshoppers reared in four different grassland patches in Inner Mongolia. Grasshoppers showed different degrees of PP associated with unique gene expressions and different habitat plant community compositions. Grasshopper performance variables were susceptible to habitat environment conditions and closely associated with plant architectures. Intriguingly, eco-transcriptome analysis revealed five potential candidate genes playing important roles in grasshopper performance, with gene expression closely relating to PP and plant community factors. By linking the grasshopper performances to gene profiles and ecological factors using canonical regression, we first demonstrated the eco-transcriptomic architecture of grasshopper phenotypic traits. Regression biplot revealed plant food type, plant density, coverage, and height were the main ecological factors influencing PP, while insect cuticle protein (ICP), negative elongation factor A (NELFA), and lactase-phlorizin hydrolase (LCT) were the key genes associated with PP. Our study gives a clear picture of gene-environment interaction in the formation and maintenance of PP and enriches our understanding of the transcriptional events underlying molecular control of rapid phenotypic plasticity associated with environmental variability. The findings of this study may also provide new targets for pest control and highlight the significance of ecological management practice on grassland conservation.Publisher PDFPeer reviewe

Poljoprivreda i hrana

This research was supported by the earmarked fund for China Agriculture Research System (CARS-34-07B), the Innovation Project of the Chinese Academy of Agricultural Sciences, and the China Scholarship Council-University of St Andrews Joint Scholarship. The earmarked fund for China Agriculture Research System (CARS-34-07B) and the Innovation Project of the Chinese Academy of Agricultural Sciences supported the design, sample collection, analysis, and interpretation of data as well as writing the manuscript. Xinghu Qin is funded by the China Scholarship Council and University of St Andrews Joint Scholarship.Background The grasshopper Oedaleus asiaticus Bey-Bienko (Acrididae: Oedipodinae) is a dominant and economically important pest that is widely distributed across the Mongolian plateau. This herbivore pest causes major damage to the grassland of the Inner Mongolian steppe in China. The population dynamics of herbivore pests is affected by grassland management practices (e.g., mowing and heavy livestock grazing) that alter plant community structures and stoichiometric characteristics. For example, O. asiaticus outbreak is closely associated with plant preference changes caused by nitrogen loss from heavy livestock grazing. However, the manner by which small-scale variation in vegetation affects grasshopper performance and promotes outbreak is poorly characterized. To address this question, we investigated the relationship between small-scale (1 m2) vegetation variability and measures of O. asiaticus performance associated with plant stoichiometric characteristics. Results We found that food preferences of O. asiaticus varied significantly, but maintained a specific dietary structure for different plant compositions. Notably, small-scale changes in plant community composition significantly affected grasshopper food preference and body size. Partial least-square modeling indicated that plant proportion and biomass affected grasshopper body size and density. We found that this effect differed between sexes. Specifically, female body mass positively correlated with the proportion of Stipa krylovii grass, whereas male mass positively correlated with the proportion of Artemisia frigida grass. Further analyses indicated that grasshopper performance is closely associated with plant stoichiometric traits that might be responsible for the pest’s plague. Conclusions This study provides valuable information for managing grasshoppers using rational grassland management practices.Publisher PDFPeer reviewe

A Multi-Objective Trajectory Planning Method for Collaborative Robot

Aiming at the characteristics of high efficiency and smoothness in the motion process of collaborative robot, a multi-objective trajectory planning method is proposed. Firstly, the kinematics model of the collaborative robot is established, and the trajectory in the workspace is converted into joint space trajectory using inverse kinematics method. Secondly, seven-order B-spline functions are used to construct joint trajectory sequences to ensure the continuous position, velocity, acceleration and jerk of each joint. Then, the trajectory competitive multi-objective particle swarm optimization (TCMOPSO) algorithm is proposed to search the Pareto optimal solutions set of the robot’s time-energy-jerk optimal trajectory. Further, the normalized weight function is proposed to select the appropriate solution. Finally, the algorithm simulation experiment is completed in MATLAB, and the robot control experiment is completed using the Robot Operating System (ROS). The experimental results show that the method can achieve effective multi-objective optimization, the appropriate optimal trajectory can be obtained according to the actual requirements, and the collaborative robot is actually operating well

EXPERIMENTAL AND NUMERICAL SIMULATION ON THE STARTING PERIOD OF A CENTRIFUGAL PUMP

ABSTRACT The centrifugal pump is applied widely in many fields with significant advance made in the understanding of the key technical phenomena related to its running at constant rotating speed; and more and more studies are concerned showing that the pressure increases with time going