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Interleukin-2 inducible T cell kinase (ITK) plays a predominant role in the T-cell receptor (TCR) signaling cascade to ensure valid T-cell activation and function. Nevertheless, whether it regulates T-cell response of early vertebrates remains unknown. Herein, we investigated the involvement of ITK in the lymphocyte-mediated adaptive immune response, and its regulation to T-cell activation in the Nile tilapia Oreochromis niloticus. Both sequence and structure of O. niloticus ITK (OnITK) were remarkably conserved with its homologues from other vertebrates, implying its potential conserved function. OnITK mRNA was extensively expressed in lymphoid-related tissues, and with the relative highest level in peripheral blood. Once Nile tilapia was infected by Edwardsiella piscicida, OnITK in splenic lymphocytes was significantly up-regulated on 7-day post infection at both transcription and translation levels, suggesting that OnITK might involve in the primary adaptive immune response of teleost. Furthermore, upon splenic lymphocytes were stimulated by T-cell specific mitogen PHA, OnITK mRNA and protein levels were dramatically elevated. More importantly, treatment of splenic lymphocytes with specific inhibitor significantly crippled OnITK expression, which in turn impaired the inducible expression of T-cell activation markers IFN-γ, IL-2 and CD122, indicating the critical roles of ITK in regulating T-cell activation of Nile tilapia. Taken together, our results suggest that ITK takes part in the lymphocyte-mediated adaptive immunity of tilapia, and is indispensable for T-cell activation of teleost. Our findings thus provide novel evidences for understanding the mechanism regulating T-cell immunity of early vertebrates, as well as the evolution of adaptive immune system.

The conformability is yet a challenge for most soft robotic grippers due to the continuous motion and deformation of these machines under external force. Herein, inspired by the movement mechanism of human fingers, we propose a novel tendon-driven soft robotic finger with a preprogrammed bending configuration and a human finger like sequential motion that can be obtained by matching the stiffness gradient of the finger joints with three-dimensional (3D) printing technology. The contents of this article are organized as follows. First, the effect of the anisotropy caused by 3D printing filling direction on the mechanical property is investigated by tensile test. Then, kinematic, stiffness, and fingertip trajectory models are established to analyze the influence of the cross-section thickness and width on the bending and bearing capacity of the finger joint. Furthermore, several experiments are conducted on a self-built experimental platform to evaluate the advantages of sequential motion induced by stiffness gradients. Results reveal that soft robotic fingers with sequential motion show excellent conformability on the object surfaces with various curvatures and outperform nonsequential motion fingers with larger envelop range. Without changing motion trajectories of the fingertip, the deformability of the finger can be tuned by adjusting only the stiffness of the joint. Besides, a two-finger gripper is developed, which presents the capability of grasping objects with different shapes and weights in practical applications. The sequential motion mechanism proposed in this study shows promising potential in soft grippers and robotic design.

Direct ignition of a gas turbine combustor using blast furnace gas fuel has become a critical issue at present. As an alternative technology of traditional spark plug ignition, plasma-assisted ignition has excellent performance in the gas turbine combustor. In this paper, the ignition system is designed to conduct a direct ignition experiment using the plasma and spark plug igniter. Then, the plasma jet characteristics, ignition limit, and flame propagation of the blast furnace gas combustor are analyzed. The results show that, using blast furnace gas fuel in the gas turbine combustor, the direct ignition of spark plug igniter fails and direct ignition of the plasma igniter succeeds. The jet from the plasma igniter is conical with a length of 30 mm and a diameter of 8 mm, which contains various active species (O、, O*、, O+、, O2+、, N2*, and, N2+). With the increase of air flow rate in the combustor, the equivalence ratio of plasma ignition limit increases from 0.7 to 0.83, and the time required for successful ignition increases from 860 ms to 4300 ms. Meanwhile, the flame propagates from a unidirectional mode to a bidirectional mode in the combustor. The laminar flame characteristics and ignition delay time of BFG/air mixtures were investigated by CHEMKIN package using the Gri-Mech 3.0 model. The active species in the plasma jet can shorten the ignition delay time from 1E-4s to 1E-5s and improve the laminar burning velocities from 7.58 cm/s to 10.90 cm/s. A large-scale initial flame kernel with concentrated energy is formed rapidly so that the flame can successfully propagate to the recirculation zone and burn stably. Finally, the blast furnace gas fuel was successfully ignited directly by the plasma igniter.

The three-dimensional turbulent swirling flame in an internally-staged combustor is numerically investigated. Four cases over a range of swirl intensities are explored by the Flamelet Generated Manifold model in this paper. Special attention is paid to analyzing the variation of the flow field, temperature, major species concentrations and emissions. The results clearly show the effects of swirl number on the size of the center recirculation zone, fuel distribution and combustion characteristics. When the third premixed stage swirl number increases from 0.6 to 1.2, the axial length of the center recirculation zone decreases by 3.7%, while the radial length increases by 6.9%. The characteristics of the flow field play an important role in the spatial distribution of the fuel, which further affects the temperature distribution in the combustor. The backflow effect is enhanced, resulting in a greater concentration of fuel at the outlet of the swirler. After the maximum temperature is reached at the exit position of the pilot stage, the temperature decreases compared to the peak temperature downstream as the proportion of premixed combustion mode increases. This creates a high concentration region of OH at the outlet of the pilot stage injector and the heat release region is squeezed upstream. At the same time, the volume of the high-temperature region downstream of the pilot stage is reduced. In addition, as the swirl number of the third premixed stage increases from 0.6 to 1.2, the emissions of NO and CO decrease by 28.7% and 75%, respectively.

As an indispensable raw material in blast furnace ironmaking, coke plays an important role, which is also the key to low-carbon smelting and reducing ironmaking carbon emissions, so it is necessary to study its quality, degradation behavior, and microstructure evolution. In this work, the pore structure and micromorphology of the blast furnace incoming coke (IC) and tuyere coke (TC) were analyzed comprehensively by comparative research methods. The results showed that the microcrystalline structure of TC was more orderly than that of IC. In addition, the order degree of the coke microcrystalline structure increased first and then decreased in the radial direction and reached the highest value at the distance of 1–2 m from the tuyere. The porosity of radial TC increased obviously. The pore wall became thinner, and the pore size of the original micropores in TC expanded. Simultaneously, large numbers of micropores were also generated, and cracks appeared, resulting in the specific surface area and pore volume of TC becoming higher than that of IC. Moreover, the graphite structure inside TC increased, and the crystal structure became larger. In the radial direction, with an increase in temperature, the number of amorphous structures in coke decreased, the ordering increased, and the graphite structure continued to grow. However, along the direction of the furnace core, a decrease in temperature led to the stagnation of amorphous structure content and a decrease in graphitization degree.

With the development of large-scale blast-furnace and oxygen-rich coal-injection technology, as well as national green and low-carbon policy requirements, the ironmaking process has increasingly strict requirements for blast-furnace raw materials, such as new and higher requirements for coke quality and thermal performance. In this study, the melting loss reaction in a blast furnace was simulated under laboratory conditions and the microstructure evolution of coke after melting loss under CO2 and CO2 + H2O conditions was studied. The results showed that under a CO2 atmosphere, the specific surface area and pore volume of coke and the number of micropores in coke first increased and then decreased with the increase in reaction time, while the average pore size first decreased from 17.289 to 8.641 nm and then increased to 9.607 nm. In the gasification reaction between CO2 and coke, the relative content of the graphitized structure (IG/IAll) increased first, then decreased and then increased with the increase in reaction time, while the change trends of disordered structure (ID3/IG) and unstable structure (ID4/IG) were opposite to IG/IAll, indicating that coke still tended to be more orderly with the increase in time. In the mixed atmosphere of CO2 and H2O, the specific surface area and IG/IAll of coke increased with the increase in H2O content. However, when the proportion of H2O exceeded 50%, the specific surface area decreased slightly, and the pore-size value corresponding to the peak value in the pore-size distribution curve shifted to the right, and the average pore-size increased in the nanosize range.

Atomic-scale friction has been investigated for a long time which is vital in reducing energy dissipation in MEMS, and most of the factors which can affect friction such as velocity, temperature, normal force, angle, and so on, have been applied to study friction. But the starting points of the scan path of the tip are not discussed very concretely. In this essay, molecular simulation and numerical analysis are used to investigate how the starting points of path and other elements influence friction. The result of molecular simulation is explained by the two-dimensional Prandtl–Tomlinson model. The moving path of the tip affected by angle, initial positions, and temperature, is plotted on the interaction potential energy surface of silicon, so it is easy to know the way that causes the change of lateral force from the figure. Conclusions are drawn as follows: Lateral force becomes the smallest when the tip moves at the angle of 45° because its path do not need to be corrected to the moving direction as set before, and energy barrier of the path at 45° is the lowest in all of the angles. All of the scanning lines that start at different initial locations are centralized to a narrow band, lateral force reaches its minimum when it moves in the line beginning at one-quarter or three-quarters of lattice whose average energy difference of each step is the least rather than in any other starting positions. Temperature can assist the tip to reside in a larger area and move more tortuous to surmount the energy peak instead of reducing energy barrier of friction which is different from traditional explanation.

As a pleiotropic cytokine mainly secreted by CD4

The braking mechanisms to protect the host from tissue damage and inflammatory disease caused by an overexuberant immune response are common in many T cell subsets. However, the negative regulation of T cell responses and detailed mechanisms are not well understood in early vertebrates. In the current study, using a Nile tilapia (Oreochromis niloticus) model, we investigated the suppression of T cell immunity by IL-10. Tilapia encodes an evolutionarily conserved IL-10, whose expression in lymphocytes is markedly induced during the primary adaptive immune response against Aeromonas hydrophila infection. Activated T cells of tilapia produce IL-10, which in turn inhibits proinflammatory cytokine expression and suppresses PHA-induced T cell activation. Moreover, administration of IL-10 impairs the proliferation of tilapia T cells, reduces their potential to differentiate into Th subsets, and cripples the cytotoxic function, rendering the animals more vulnerable to pathogen attack. After binding to its receptor IL-10Ra, IL-10 activates the JAK1/STAT3 axis by phosphorylation and enhances the expression of the suppressor of cytokine signaling 3 (SOCS3), which in turn attenuates the activation of the NF-κB and MAPK/ERK signaling pathways, thus suppressing the T cell response of tilapia. Our findings elucidate a negative regulatory mechanism of T cell immunity in a fish species and support the notion that the braking mechanism of T cells executed through IL-10 existed prior to the divergence of the tetrapod lineage from teleosts. Therefore, this study, to our knowledge, provides a novel perspective on the evolution of the adaptive immune system.

Although several empirical wear formulas have been proposed, theoretical approaches for predicting surface topography evolution during sliding wear are limited. In this study, we propose a novel wear-prediction method, wherein the energy-based Arrhenius equation is combined with a mixed elastohydrodynamic lubrication (EHL) model to predict the point-contact wear process in mixed lubrication. The surface flash temperature and contact pressure are considered in the wear model. Simulation results are compared with the experimental results to verify the theory. The surface topography evolutions are observed during the wear process. The influences of load and speed on wear are investigated. The simulation results based on the Arrhenius equation relationship shows good agreement with the results of experiments as well as the Archard wear formula. However, the Arrhenius equation is more accurate than the Archard wear theory in some aspects, such as under high-temperature conditions. The results indicate that combining the wear formulas with the mixed EHL simulation models is an effective method to study the wear behavior over time.

In order to investigate the formation process and propagation characteristics of detonation wave, developing process of detonation wave from initiation to stable detonation formation under non-premixed conditions has been studied by experiments and numerical simulation. The results show that when mass flow rates of air and hydrogen are 158.957 g/s and 2.728 g/s respectively, stable detonation can be formed in the combustor. Due to the lower inlet pressure, there is an unstable stage in combustor before the stable detonation is formed. Reducing the air pressure will increase the lowest detonation limit of combustor and lead to flame-out and re-initiation in the combustor. The propagation direction of detonation wave may change after re-initiation. Non-premixed intake structure lead to the inconsistency of rotating detonation combustion fluid in the radial direction. Moreover, peak pressure appears near the outer wall, while peak temperature appears near the inner wall.

Calcium ion (Ca2+) is a widespread and primitive second messenger that regulates physiological cell functions in almost all life beings. Ca2+ influx-induced NFAT activation is essential for T cell function and adaptive immunity. However, whether and how Ca2+ signaling modulates T cell immunity in early vertebrates, especially in nontetrapods, remains largely unknown. To address these questions, a Nile tilapia (Oreochromis niloticus) model was employed to investigate the regulation of ancestral T cell immunity by Ca2+–NFAT signaling in jawed fish. In Nile tilapia, an evolutionarily conserved Ca2+–NFAT signaling pathway is involved in the primary adaptive immune response during Streptococcus agalactiae infection. Meanwhile, T cell signals trigger several events along the Ca2+–NFAT axis in this early vertebrate, including Ca2+ influx, calcineurin activation, and NFAT nuclear import. More critically, suppression of Ca2+–NFAT signaling by the calcineurin inhibitor cyclosporine A impairs primordial T cell activation, clonal expansion, and infection clearance. Mechanistically, Nile tilapia NFAT interacts with several other transcription factors for potent gene expression, and T cells in this nontetrapod employ Cabin1 and DYRK1A to regulate NFAT nuclear import and export, respectively. To the best of our knowledge, this study is the first to demonstrate the regulatory mechanism of Ca2+–NFAT signaling on T cell immunity in a nontetrapod species. We suggest that modulation of T cell immunity by Ca2+–NFAT signaling is a primitive strategy that already existed prior to the divergence of bony fish from the tetrapod lineage. The findings of this study provide valuable perspectives for understanding the evolution of adaptive immune system.

Transforming growth factor-β1 (TGF-β1) can suppress the activation, proliferation, and function of many T-cell subsets, protecting organisms from inflammatory and autoimmune disease caused by an overexuberant immune response. However, whether and how TGF-β1 regulates T-cell immunity in early vertebrates remain unknown. Here, using a Nile tilapia (Oreochromis niloticus) model, we investigated suppression of the T-cell response by TGF-β1 in teleost species. Tilapia encodes an evolutionarily conserved TGF-β1, the expression of which in lymphocytes is significantly induced during the immune response following Edwardsiella piscicida infection. Once activated, tilapia T cells increase TGF-β1 production, which in turn suppresses proinflammatory cytokine expression and inhibits T-cell activation. Notably, we found administration of TGF-β1 cripples the proliferation of tilapia T cells, reduces the potential capacity of Th1/2 differentiation, and impairs the cytotoxic function, rendering the fish more vulnerable to bacterial infection. Mechanistically, TGF-β1 initiates the TGF-βR/Smad signaling pathway, and triggers the phosphorylation and nuclear translocation of Smad2/3. Smad3 subsequently interacts with several transcriptional partners to repress transcription of cytokines IL-2 and IFN-γ, but promote transcription of immune checkpoint regulator CTLA4 and transcription factor Foxp3. Furthermore, TGF-β1/Smad signaling further utilizes Foxp3 to achieve the cascade regulation of these T-cell genes. Taken together, our findings reveal a detailed mechanism by which TGF-β1 suppresses the T cell-based immunity in Nile tilapia, and support the notion that TGF-β1 had already been employed to inhibit the T-cell response early in vertebrate evolution, thus providing novel insights into the evolution of the adaptive immune system.

Electrothermal actuators (ETAs) have received great attention among soft actuators due to their simple structure and light weight. Since most of the application scenarios of ETAs are on soft robots, the current research on ETAs mainly focuses on the improvement of their max deformation. In fact, important application prospects of soft actuators lie in biological and medical aspects, such as smart wearable devices. This remind us to consider the issues of safety and comfort, which have been neglected for a long time. In this work, we report an ultralight, porous Nafion/Ag composite microfiber film actuator prepared by blow-spinning. Unlike most ETAs, it has porous fibrous structure and can achieve considerable deformation in a safe temperature range for the organisms (30 °C–67 °C). The film actuator, with a low density (about 0.45 g cm−3), can bend in a short time (within 15 s) to an angle of about 91° and achieve a displacement of 11.2 mm when applied a low voltage (2.4 V). Owing to the processing method of blow-spinning, the film actuator presents a series of excellent characteristics, including softness, light weight and porosity, etc. To summarize, the Nafion/Ag composite microfiber film actuator shows great potential in soft robots and smart wearable devices due to their properties of low driven voltage, low weight and moderate working temperature range.

The reduced stress resistance and increased disease risk associated with high-fat diet (HFD) in animals have attracted increasing attention. However, the effects of HFD on adaptive immunity in early vertebrates, especially non-tetrapods, remain unknown. In this study, using Nile tilapia (Oreochromis niloticus) as a model, we investigated the effects of HFD on the primordial T-cell response in fish. Tilapia fed with an HFD for 8 weeks showed impaired lymphocyte homeostasis in the spleen, as indicated by the decreased number of both T and B lymphocytes and increased transcription of proinflammatory cytokines interferon-γ and interleukin-6. Moreover, lymphocytes isolated from HFD-fed fish or cultured in lipid-supplemented medium exhibited diminished T-cell activation in response to CD3ε monoclonal antibody stimulation. Moreover, HFD-fed tilapia infected by Aeromonas hydrophila showed decreased T-cell expansion, increased T-cell apoptosis, reduced granzyme B expression, and impaired infection elimination. Additionally, HFD attenuated adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) activity in tilapia lymphocytes, which in turn upregulated fatty acid synthesis but downregulated fatty acid β-oxidation. Altogether, our results suggest that HFD impairs lymphocyte homeostasis and T cell-mediated adaptive immune response in tilapia, which may be associated with the abnormal lipid metabolism in lymphocytes. These findings thus provide a novel perspective for understanding the impact of HFD on the adaptive immune response of early vertebrates.

As is known to all, diabetes metellius is a global health threaten and it has caused worldwide attention of scientists. To get a better investigation of the drug design of diabetes, we used heuristic method to established the linear model and used Gradient Boosting Regression to establish the nonlinear model of Fructose-1,6-Bisphosphatse inhibitor successively. In this study, 84 derivatives of N-Arylsulfonyl-Indole-2-Carboxamide were introduced into the models, two outstanding QSAR models with 2 molecule descriptors were established successfully. Grandient Boosting Regression rendered a good correlation with R2 of 0.943 and MSE of 0.135 for the training set, 0.916 and 0.213 for test set, which also proves the feasibility of the implementation of the new method GBR in the field of QSAR. Meanwhile, the optimal model displayed wonderful statistical significance. This study shows unlimited potential for design of new drugs for diabetes.

To study the effect of fuel stage proportion on flame position and combustion characteristics of the internally-staged combustor, a detailed numerical investigation is performed in the present paper. The prediction method of flame position is established by analyzing the variations of the distribution of intermediate components and the turbulent flame speed. Meanwhile, the flame position is simulated to verify the accuracy of the prediction method. It is demonstrated that the flame position prediction model established in this paper can accurately predict the flame position under different fuel stage proportions. On this basis, special attention is paid to analyze the variation of velocity field, temperature field, distribution of intermediate components and emissions under different fuel stage proportions. As the proportion of pilot fuel stage increases slightly, the mass fraction of fuel at the combustor dome increases. In addition, the combustion characteristics change significantly with the increase in the proportion of pilot stage fuels. The flame moves downstream and the high temperature area increases as the proportion of pilot fuel increases. In particular, when the proportion of pilot stage reaches 3%, the highest flame temperature is generated due to the most concentrated reaction area, resulting in the largest emission of NOx. At the same time, due to the most complete reaction, the minimum CO emission is produced. When the proportion of pilot fuel stage reaches 1%, the NOx emission is the lowest, and the highest CO emission is generated due to the incomplete reaction.

The performance of the ignition device has an impressive impact on the working range and reliability of gas turbines. In the extreme conditions and with low pollutant emissions, gas turbines advancing higher requirements for the better performance of the ignition device. Due to its exceptional advantages, plasma ignition technology has become a research hotspot for all the scholars around the globe. The plasma ignition device ignites by the plasma jet with high-temperature and abundant active species, which has the advantages of large ignition energy, concentrated energy and strong penetration of the plasma jet. In the current research work, experimental research work is carried out on the plasma ignition using the plasma jet. The voltage and current features of plasma power supply are measured by a voltage probe and a current probe. The developed process of plasma jet generation is captured by a high-speed camera. The characteristics of plasma jet morphology and the law of the influence of the variable electrode gap (1.5 mm-3.5 mm) on the features of the plasma jet morphology are investigated. The experimental results demonstrate that during plasma ignition the discharge voltage and the current have a maximum peak-to-peak value of 11.67kV and 70A. The maximum reverse voltage and the reverse current are 2000V and 15A during the discharge and breakdown. The plasma jet produced active species along with a cone-shaped high-temperature during the air breakdown. The structure of the plasma jet can be divided into two portions, central high-temperature kernel (HTK) and peripheral halo gas (PHG) by gray processing of high-speed camera pictures. Different discharge electrode gap is leading to change the size of the plasma jet high-temperature kernel and the peripheral halo gas. If the gap of the discharge electrode is increased, then the area of the high-temperature kernel is also increased.

Investigations of mixing process, combustion and emission characteristics have been performed in a double-cone premixed burner under various mixing distances. The complex flow field and flame structure are accurately captured by the simulation model. The modified unmixedness coefficient, flame index, NO, CO emissions have been calculated and analyzed in detail. Numerical results show that the dimensionless mixing distance has a significant impact on the fuel mixing effect and then affects the high temperature zone position and emissions. With the increase of dimensionless mixing distance, the mixing process is mainly affected by the inner recirculation zone instead of the outer recirculation zone. The high temperature zone changes from the corner to the center. When the dimensionless mixing distance is 0.15, the peak concentration of CH2O and OH is below 1500 K, and the concentrations are relatively lower above 1500 K. The concentration scatter is relatively concentrated, which indicates that the mixing quality is the best and the reaction is the most uniform. The combustion mode is dominated by premixed combustion. When the dimensionless mixing distance is 0.1 and 0.2, regions with higher concentration of CH2O and OH still exist after 2000 K. The proportion of non-premixed combustion mode increases and the combustion temperature is high. NO and CO emissions first decrease and then increase with the increase of mixing distance from 0.1 to 0.2. According to the present analysis, the emission is the lowest when the dimensionless mixing distance is 0.15.

T cells suddenly appeared in jawed fish ∼450 million years ago. Biological studies of fish T cells may provide helpful evidence to understand evolution of adaptive immune systems. To this end, using a Nile tilapia (Oreochromis niloticus) model, we revealed the regulatory mechanism of adaptive immunity mediated by ancestral T cells in jawed fish. Nile tilapia T cells as well as a tightly regulated mammalian/mechanistic target of rapamycin complex 1 (mTORC1) pathway participate in the cellular adaptive immune response during Streptococcus agalactiae infection. Blockade of mTORC1 signaling by rapamycin impairs T cell activation and Ag-induced proliferation in this early vertebrate. More critically, we show that signals from mTORC1 are indispensable for primordial effector T cells to eliminate infection by promoting the expression of proinflammatory cytokines, cytotoxic-related molecules, and proapoptotic genes. Mechanistically, teleost mTORC1 directs effector T cell function by coordinating multiple metabolic programs, including glycolysis, glutaminolysis, and lipogenesis through activating key transcription factors c-Myc, HIF-1α, and sterol regulatory element–binding proteins, and thus links immune signals to metabolic reprogramming in jawed fish. To our knowledge, these results represent the first description of the regulatory mechanism for T cell–mediated adaptive immunity in a fish species. From an evolutionary viewpoint, our study suggests that primordial T cells are armed with sophisticated regulatory strategies like those in modern T cells prior to the divergence of bony fish from the tetrapod lineage. Therefore, our findings fill in an important gap regarding evolution of the adaptive immune system.

H-Ras is a guanosine triphosphatase (GTPase), which acts as a molecular switch and controls multiple important cellular processes including lymphocyte activation and function. However, regulatory mechanism of adaptive immune response by H-Ras remains unclear in non-mammalian animals. In the present study, we investigated the involvement of H-Ras in lymphocyte activation with a teleost model Oreochromis niloticus. H-Ras from O. niloticus (On-H-Ras) is highly conserved with those from other vertebrates. The mRNA of On-H-Ras showed a wide expression pattern in the lymphoid-tissues and with the highest level in liver. After Aeromonas hydrophila infection, transcription of On-H-Ras was significantly induced on day 8 but came back to basal level on day 16, suggesting that On-H-Ras potentially participated in primary response during the adaptive immunity. Furthermore, On-H-Ras mRNA was obviously up-regulated when leukocytes were activated by T lymphocyte mitogen PHA in vitro. Meanwhile, protein level of H-Ras was also augmented once leukocytes were stimulated with lymphocyte receptor signaling agonist PMA and ionomycin. More importantly, once Ras activity was inhibited by specific inhibitor, the up-regulation of lymphocyte activation marker CD122 was obviously impaired during lymphocyte activation process. Therefore, On-H-Ras regulated lymphocyte activation through both mRNA and protein level. Altogether, our results illustrated the involvement of H-Ras in teleost adaptive immunity via controlling lymphocyte activation, and thus provided a novel perspective to understand evolution of the lymphocyte-mediated adaptive immunity.

TiC ceramics have the characteristics of high melting point and density, and titanium reserves on earth are extremely large; therefore, TiC ceramics are considered ultra-high temperature materials with great research value. However, the development of TiC-based ultra-high temperature composites has been seriously hindered by their poor mechanical properties. At present, improvement of the mechanical properties of TiC is mainly accomplished by adding a second phase. In this paper, the research status of modified elements-, nitrides-, and metal-reinforced TiC matrix composites is presented. The microstructure, phase composition, and toughening mechanism of TiC matrix composites reinforced by a second phase are described. The influence of the reaction products on the matrix during the toughening process is also discussed.

Killer cell lectin-like receptor G subfamily 1 (KLRG1) is a receptor generally expressed on effector CD8+ T cells or NK cells at terminal differentiation stage, and it will be highly induced for lymphocyte cytotoxicity upon pathogen infection or lymphocyte activation. However, little is known about the character or function of KLRG1 in lower vertebrates. In present study, we reappraised a molecule that previously defined as KLRG1 in the genomic sequence of Nile tilapia Oreochromis niloticus, and identified it as an atypical KLRG1-like molecule (defined as On-KLRG1-L), and illustrated its potential function serving as a marker representing effector T lymphocytes of fish species. On-KLRG1-L consists of two C-type lectin-like domains (CTLDs) without transmembrane region, and the tertiary structure of the CTLD is highly alike to that in mouse KLRG1. As a CTLD-containing protein, the recombinant On-KLRG1-L could bind PGN and several microbes in vitro. On-KLRG1-L was widely expressed in immune-associated tissues, with the highest expression level in the gill. Once Nile tilapia is infected by Aeromonas hydrophila, mRNA level of On-KLRG1-L in spleen lymphocytes were significantly up-regulated on 5 days after infection. Meanwhile, On-KLRG1-L protein was also induced on 5 or 8 days after A. hydrophila infection. Furthermore, we found both mRNA and protein levels of On-KLRG1-L were dramatically enhanced within several hours after spleen lymphocytes were activated by T cell-specific mitogen PHA in vitro. More importantly, the ratio of On-KLRG1-L+ T cells was also augmented after PHA stimulation. The observations suggested that the KLRG1-like molecule from Nile tilapia participated in lymphocyte activation and anti-bacterial adaptive immune response, and could serve as an activation marker of T lymphocytes. Our study thus provided new evidences to understand lymphocyte-mediated adaptive immunity of teleost.

Serving as a significant signaling molecule, RAC-alpha serine/threonine-protein kinase (Akt1) plays indispensable roles in cell cycle, growth, survival, metabolism, as well as immune response. However, how Akt1 regulates adaptive immune response in early vertebrate, especially the teleost, is largely unknown. Here, using a Nile tilapia Oreochromis niloticus model, we investigated the regulatory role of Akt1 in adaptive immunity of teleost. Both sequence and structure of the O. niloticus Akt1 (OnAkt1), were evolutionarily conserved comparing with the counterparts from other vertebrates. mRNA of OnAkt1 was widely expressed in lymphoid organs/tissues of Nile tilapia, with relative higher level in PBL. After Nile tilapia was infected by Aeromonas hydrophila, both transcription and phosphorylation levels of OnAkt1 were obviously elevated in spleen lymphocytes at the adaptive immune stage, suggesting Akt1 participated in primary adaptive immune response of Nile tilapia. Furthermore, OnAkt1 transcript or phosphorylation was dramatically augmented after spleen lymphocytes were activated by T cell specific mitogen PHA or lymphocyte agonist PMA. More critically, inhibition of Akt1 by specific inhibitor crippled the activation of downstream mTORC1 signaling, and impaired the up-regulation of T cell activation markers CD44, IFN-γ and CD122 in spleen lymphocytes upon PHA-induced T cell activation. Meanwhile, blockade of Akt1-activated mTORC1 signaling also decreased the frequency of BrdU+ lymphocytes during A. hydrophila infection, indicating the critical role of Akt1 in regulating lymphocyte proliferation of Nile tilapia. Together, our results demonstrated that Akt1 modulated adaptive immune response of Nile tilapia by promoting lymphocyte activation and proliferation via mTORC1 signaling. Our study enriched the regulatory mechanism of lymphocyte-mediated adaptive immunity in teleost, and thus provided novel insights into the evolution of adaptive immune system.