Modified mathematical models based on imaginary plane zone method in reheating furnace were developed in which non-gray radiation properties of gas were considered,and the Newton＇s method and the finite difference me...Modified mathematical models based on imaginary plane zone method in reheating furnace were developed in which non-gray radiation properties of gas were considered,and the Newton＇s method and the finite difference method were adopted. Effects of productivity,fuel consumption,fuel-air ratio,calorific value of fuel and inserting depth of thermocouple on total heat exchange factor along the length of reheating furnace were investigated. The results show that total heat exchange factor increases with productivity or inserting depth of thermocouple,and it decreases when fuel consumption,fuel-air ratio or calorific value of fuel increases. The results are valuable for dynamical compensation of total heat exchange factor for online control mathematical models in reheating furnace.展开更多
BACKGROUND Phosphatidylinositol-3,4,5-trisphosphate dependent Rac exchange factor 1(PREX1)was reported to be overexpressed in some cancers and involved in cancer development,but its expression and significance in gast...BACKGROUND Phosphatidylinositol-3,4,5-trisphosphate dependent Rac exchange factor 1(PREX1)was reported to be overexpressed in some cancers and involved in cancer development,but its expression and significance in gastric cancer remain unclear.AIM To evaluate the expression of PREX1 in gastric cancer and its significance in the development of gastric cancer,especially to evaluate the potential mechanism of PREX1 in gastric cancer.METHODS Bioinformatic analysis was performed in order to examine the expression of PREX1 in gastric cancer.The relationship between the survival rate of gastric cancer patients and PREX1 expression was assessed by Kaplan Meier portal.The Gene Set Enrichment Analysis and the correlation between PREX1 and transforming growth factor(TGF)β1 pathway-related mediators were evaluated by cBioPortal for Cancer Genomics.Western blotting and reverse transcriptase polymerase chain reaction assay were used to test the role of TGFβ1 on the expression of PREX1.Western blotting and dual-luciferase reporter system was used to evaluate the effect of PREX1 on the activation of TGFβ1 pathway.Wound healing and Transwell assay were used to assess the effect of PREX1 on the metastasis activity of gastric cancer cells.RESULTS PREX1 was overexpressed in the gastric tumors,and the expression levels were positively associated with the development of gastric cancer.Also,the high expression of PREX1 revealed poor prognosis,especially for those advanced and specific intestinal gastric cancer patients.PREX1 was closely involved in the positive regulation of cell adhesion and positively correlated with TGFβ1-related mediators.Furthermore,TGFβ1 could induce the expression of PREX1 at both the protein and mRNA level.Also,PREX1 could activate the TGFβ1 pathway.The induced PREX1 could increase the migration and invasion activity of gastric cancer cells.CONCLUSION PREX1 is overexpressed in gastric cancer,and the high level of PREX1 predicts poor prognosis.PREX1 is closely associated with TGFβsignaling and promotes the metastasis of gastric cancer cells.展开更多
BACKGROUND Phosphatidylinositol-3,4,5-trisphosphate dependent Rac exchange factor 1(PRex1)was reported to be a risk factor in several cancers,including breast cancer,lung cancer,and melanoma,but its expression and rol...BACKGROUND Phosphatidylinositol-3,4,5-trisphosphate dependent Rac exchange factor 1(PRex1)was reported to be a risk factor in several cancers,including breast cancer,lung cancer,and melanoma,but its expression and role in hepatocellular carcinoma(HCC)have not yet been fully studied.AIM To explore the expression of P-Rex1 in HCC,and further evaluate its potential application in the diagnosis and prognosis of HCC,especially in hepatitis B virus(HBV)-related patients.METHODS P-Rex1 expression in HCC was evaluated by real-time-quantitative polymerase chain reaction.The expression of P-Rex1 was subjected to correlation analysis with clinical features,such as lymph node invasion,distant metastasis,HBV infection,patient’s age and gender.Receiver operating characteristic analysis was used to examine the potential role of P-Rex1 as a diagnostic biomarker in HCC.Kaplan-Meier analysis was used to determine the association between P-Rex1 expression and overall survival,progression-free survival and relapse-free survival.Bioinformatic analysis was used to validate the clinical findings.RESULTS P-Rex1 expression was significantly increased in HCC tumors than adjacent tissues.The expression of P-Rex1 was higher in HCC patients with lymph node invasion,distant metastasis,HBV infection and positive alpha-fetoprotein,respectively.The receiver operating characteristic analysis showed that P-Rex1 was a diagnostic biomarker with a higher area under the curve value,especially in patients with HBV infection.Survival analysis showed that patients with higher P-Rex1 expression had a favorable survival rate,even in early-stage patients.CONCLUSION P-Rex1 expression was highly increased in HCC,and the expression level of PRex1 was positively correlated with tumor progression.P-Rex1 has a higher efficiency in the diagnosis of HBV-related HCC,and could also be used as a favorable prognostic factor for HCC patients.展开更多
The Guanine nucleotide exchange factor Vav2（Vav2） is a member of the Vav family that serves as an important regulators for the Rho family of Ras-related GTPases. In the current study, an ortholog（Lj-Vav2） of Vav2 ...The Guanine nucleotide exchange factor Vav2（Vav2） is a member of the Vav family that serves as an important regulators for the Rho family of Ras-related GTPases. In the current study, an ortholog（Lj-Vav2） of Vav2 was identified in the lamprey（Lampetra japonica）. To elucidate the phylogenetic relationship of Vav2, the metazoan genome databases were analyzed to mine the ortholog of Vav. It was found that Vav2 genes were only existed in vertebrates and Lj-Vav2 was the original one found in agnathans. The evolutionary dynamics of conserved motifs of Vav2 were explored using combined amino acid sequence as markers, and it is revealed that the Calponin homology（CH） domain, Dbl-homologous（DH） domain, Pleckstrin homology（PH） domain, Cysteine-rich（C1）domains, Src homology 3（SH3） domains and Src homology 2（SH2） domain were conserved throughout the Vav2 gene family in vertebrates during gene evolution. Relative quantitative real-time PCR analysis showed that the LjVav2 was distributed in the heart, kidney, supraneural myeloid body, liver, gill and lymphocyte-like cells. The LjVav2 was found to be expressed in these tissues, and the level of which was upregulated in lymphocyte-like cells after the animal was stimulated with LPS. These results indicated that the Lj-Vav2 might be involved in the immune response of lymphocyte-like cells in lamprey. Meanwhile, our findings provided a foundation for further investigation of the function of Lj-Vav2 in the primary vertebrate.展开更多
In flowering plants, male gametes are delivered to female gametophytes by pollen tubes. Although it is important for sexual plant reproduction, little is known about the genetic mechanism that controls pollen germinat...In flowering plants, male gametes are delivered to female gametophytes by pollen tubes. Although it is important for sexual plant reproduction, little is known about the genetic mechanism that controls pollen germination and pollen tube growth. Here we report the identification and characterization of two novel mutants, gnom-like 2-1 （gnl2-1） and gn12-2 in Arabidopsis thaliana, in which the pollen grains failed to germinate in vitro and in vivo. GNL2 encodes a protein homologous to the adenosine diphosphate-ribosylation factor-guanine nucleotide exchange factors, GNOM and GNL1 that are involved in endosomal recycling and endoplasmic reticulum-Golgi vesicular trafficking. It was prolifically expressed in pollen grains and pollen tubes. The results of the present study suggest that GNL2 plays an important role in pollen germination.展开更多
The plant cell wall is an important interface for sensing pathogen attack and activating signaling pathways that promote plant immune responses.THESEUS1(THE1) acts as a sensor of cell wall integrity that controls cell...The plant cell wall is an important interface for sensing pathogen attack and activating signaling pathways that promote plant immune responses.THESEUS1(THE1) acts as a sensor of cell wall integrity that controls cell elongation during plant growth.However, no specific role for THE1 in plant defense responses has been reported. Here, we found that THE1 interacts with GUANINE EXCHANGE FACTOR4(GEF4)and that both proteins play regulatory roles in plant resistance to the necrotrophic fungus Botrytis cinerea.Genetic analysis showed that THE1 and GEF4 function in the same genetic pathway to mediate plant defense responses. In addition, using transcriptome analysis, we identified various genes(such as defense-related,secondary metabolite-related, and transcription factor genes) that are likely downstream targets in the THE1-GEF4 signaling pathway. Our results suggest that THE1 functions as an upstream regulator of GEF4 signaling to positively regulate defense responses against B. cinerea in Arabidopsis.展开更多
The article presents an experimental and numerical study on thermal performance enhancement in a constant heatfluxed square-duct inserted diagonally with 45° discrete V-finned tapes(DFT).The experiments were carr...The article presents an experimental and numerical study on thermal performance enhancement in a constant heatfluxed square-duct inserted diagonally with 45° discrete V-finned tapes(DFT).The experiments were carried out by varying the airflow rate through the tested square duct with DFT inserts for Reynolds number from 4000 to 25000.The effect of the DFT with V-tip pointing upstream at various relative fin heights and pitches on heat transfer and pressure drop characteristics was experimentally investigated.Both the heat transfer and pressure drop were presented in terms of Nusselt number and friction factor respectively.Several V-finned tape characteristics were introduced such as fin- to duct-height ratio or blockage ratio(R_B=e/H = 0.075,0.1,0.15 and 0.2),fin pitch to duct height ratio(R_P= P/H=0.5,1.0,1.5 and 2.0) and fin attack angle,α = 45°.The experimental results reveal that the heat transfer and friction factor values with DFT inserts increase with the increment of R_B but the decrease of R_P.The inserted square-duct at R_B = 0.2 and R_P = 0.5 provides the highest heat transfer and friction factor while the one with R_B= 0.1 and R_P= 1.5 yields the highest thermal performance.Also,a numerical simulation was conducted to investigate the flow structure and heat transfer mechanism inside the tested duct with DFT inserts.展开更多
Guanine nucleotide exchange factors(GEFs)and guanine nucleotide-dissociation inhibitors(GDIs)regulate small GTPase proteins,which function as molecular switches in various signaling pathways,but their identification a...Guanine nucleotide exchange factors(GEFs)and guanine nucleotide-dissociation inhibitors(GDIs)regulate small GTPase proteins,which function as molecular switches in various signaling pathways,but their identification and functions in plants are not well understood.Using in-silico analysis and transgenic approaches,respectively,we dissected the evolutionary relationships and functions of all GEF and GDI genes in rice.Intron-exon distribution and phylogenetic analyses identified 30 GEF and 10 GDI genes in rice that shared close evolutionary relationships with other eukaryotes.Tissue-specific expression and co-expression analyses revealed that phylogenetically related genes had similar expression patterns.GEF and GDI genes were highly expressed in panicles,hulls,and stamens.Co-expression network analysis identified panicle and stamen-specific modules of co-expressed genes in both families.Mapping of these genes in known protein interactomes further identified two and one small G-protein sub-networks.A mutant library of GEF and GDI families was constructed by CRISPR knockout of each gene,and their genotypes and phenotypes were confirmed.Phenotype changes occurred with the mutation of only three genes(OsGEF5,OsGDI1,and OsGEF3).OsGEF5 and OsGDI1 single mutants exhibited significantly reduced height and longer and thinner grains,whereas OsGEF3 mutants had reduced grain length compared to the wild type.Haplotype and eGWAS analyses showed that natural variations in the three genes affected gene expression in reproductive tissues that were significantly associated with the phenotypic variation.BiFC assays demonstrated that GDI1 and GEF3 interacted with grain-size protein GS3,pointing to a role of these genes in the regulation of grain size and plant architecture connected to heterotrimeric G-proteins in rice.展开更多
MgCdc42 （Cdc42 in Magnaporthe grisea）, with high homology to ScCdc42 （Cdc42 in Saccharomyces cerevisiae）, has been demonstrated to involve in the morphogenesis and infection process. To further understand the sign...MgCdc42 （Cdc42 in Magnaporthe grisea）, with high homology to ScCdc42 （Cdc42 in Saccharomyces cerevisiae）, has been demonstrated to involve in the morphogenesis and infection process. To further understand the signaling network, the putative MgCdc42-interacting proteins were analyzed. ScCdc42-interacting protein sequences were first used to BLAST against the M. grisea genome database to retrieve their corresponding analogs. Subsequently, conserved domains of these proteins were compared and expression patterns of their encoding genes in different MgCdc42 mutation states were analyzed by semiquantitative RT-PCR. All retrieved analogs of ScCdc42-interacting proteins from the M. grisea database have conserved domains as those in S. cerevisiae. Expression of their encoding genes increased in MgCdc42CA mutant and decreased in MgCdc42KO mutant. However, MgBeml, Chin1, and MgGicl in MgCdc42DN mutant had the same expression level as that in the wild type, although MgBem4, MgBoi2, MgCdc24, MgGic2, MgRgal, and Mst20 had decreased expression level, as expected. Overall, it is concluded that there may exist a similar Cdc42 signal pathway in M. grisea as in S. cerevisiae and MgCdc42 plays a key role in the pathway.展开更多
Autophagy is a fundamental cellular process,conserved across species from yeast to mammals,that plays a crucial role in maintaining cellular homeostasis.The functionally conserved MON1-CCZ1(MC1)complex serves as a gua...Autophagy is a fundamental cellular process,conserved across species from yeast to mammals,that plays a crucial role in maintaining cellular homeostasis.The functionally conserved MON1-CCZ1(MC1)complex serves as a guanine nucleotide exchange factor(GEF)for the RAB GTPase RAB7A and is indispensable for directing RAB7A recruitment to autophagosome or lysosomal membranes.Despite its critical role,the precise molecular mechanism underlying the assembly of the human MON1A-CCZ1(HsMC1)complex and its specific GEF activity towards RAB7A has remained unclear.In this study,we report the high-resolution cryo-electron microscopy(cryo-EM)structure of the HsMC1 GEF domain in a complex with the nucleotide-free RAB7A^(N125I)at 2.85 A resolution.Our structural data demonstrate that engagement with the HsMC1 complex induces marked conformational shifts in the phosphate-binding loop(P-loop)and SwitchⅠ/Ⅱregions of RAB7A.A striking feature of this complex is the direct interaction between the P-loop of RAB7A and CCZ1,a structural detail not previously observed.Furthermore,biochemical assays targeting residues within InterfaceⅠorⅡof the HsMC1-RAB7A complex highlight their critical role in mediating the interaction and suggest a unique mechanism for nucleotide exchange facilitated by the HsMC1 complex.These findings provide novel molecular insights into the functional mechanisms of the HsMC1-RAB7A complex,offering a robust structural framework to inform future investigations into disease-related targets and therapeutic development.展开更多
Estuarial saline wetlands have been recognized as a vital role in CO_2 cycling.However,insufficient attention has been paid to estimating CO_2 fluxes from estuarial saline wetlands.In this study,the static chamber-gas...Estuarial saline wetlands have been recognized as a vital role in CO_2 cycling.However,insufficient attention has been paid to estimating CO_2 fluxes from estuarial saline wetlands.In this study,the static chamber-gas chromatography(GC) method was used to quantify CO_2 budget of an estuarial saline reed(Phragmites australis) wetland in Jiaozhou Bay in Qingdao City of Shandong Province,China during the reed growing season(May to October) in 2014.The CO_2 budget study involved net ecosystem CO_2 exchange(NEE),ecosystem respiration(Reco) and gross primary production(GPP).Temporal variation in CO_2 budget and the impact of air/soil temperature,illumination intensity and aboveground biomass exerted on CO_2 budget were analyzed.Results indicated that the wetland was acting as a net sink of 1129.16 g/m^2 during the entire growing season.Moreover,the values of Reco and GPP were 1744.89 g/m^2 and 2874.05 g/m^2,respectively;the ratio of Reco and GPP was 0.61.Diurnal and monthly patterns of CO_2 budget varied significantly during the study period.Reco showed exponential relationships with air temperature and soil temperature at 5 cm,10 cm,20 cm depths,and soil temperature at 5 cm depth was the most crucial influence factor among them.Meanwhile,temperature sensitivity(Q10) of Reco was negatively correlated with soil temperature.Light and temperature exerted strong controls over NEE and GPP.Aboveground biomass over the whole growing season showed non-linear relationships with CO_2 budget,while those during the early and peak growing season showed significant linear relationships with CO_2 budget.This research provides valuable reference for CO_2 exchange in estuarial saline wetland ecosystem.展开更多
Eukaryotic translation initiation factor eIF2B,the guanine nucleotide exchange factor(GEF)for eIF2,catalyzes conversion of eIF2·GDP to eIF2·GTP.The eIF2B is composed of five subunits,α,β,γ,δandε,within ...Eukaryotic translation initiation factor eIF2B,the guanine nucleotide exchange factor(GEF)for eIF2,catalyzes conversion of eIF2·GDP to eIF2·GTP.The eIF2B is composed of five subunits,α,β,γ,δandε,within which theεsubunit is responsible for catalyzing the guanine exchange reaction.Here we present the crystal structure of the C-terminal domain of human eIF2Bε(eIF2Bε-CTD)at 2.0-Åresolution.The structure resembles a HEAT motif and three charge-rich areas on its surface can be identified.When compared to yeast eIF2Bε-CTD,one area involves highly conserved AA boxes while the other two are only partially conserved.In addition,the previously reported mutations in human eIF2Bε-CTD,which are related to the loss of the GEF activity and human VWM disease,have been discussed.Based on the structure,most of such mutations tend to destabilize the HEAT motif.展开更多
Objective Rho guanine nucleotide exchange factor 15(ARHGEF15)is a member of the RhoGEF family that activates the Rho protein.High ARHGEF15 expression is associated with poor prognosis in patients with pancreatic cance...Objective Rho guanine nucleotide exchange factor 15(ARHGEF15)is a member of the RhoGEF family that activates the Rho protein.High ARHGEF15 expression is associated with poor prognosis in patients with pancreatic cancer.Although ARHGEF15 is abundantly expressed in endothelial cells,its detailed functions remain unknown.This study aimed to elucidate the effects of ARHGEF15 on endothelial cells and the underlying molecular mechanisms involved.Methods The ARHGEF15 gene was overexpressed or knocked down in human umbilical vein endothelial cells(HUVECs),and the results were validated via qRT-PCR and Western blotting.CCK8 and MTT assays were used to evaluate cell proliferation.Wound healing and transwell assays were used to assess cell migration.The activation of STAT3 signaling was examined by Western blotting,and STATTIC was used to inhibit STAT3 signaling.Results ARHGEF15 overexpression promoted the migration of HUVECs,and ARHGEF15 knockdown inhibited the migration of HUVECs.Neither the overexpression nor the knockdown of ARHGEF15 affected HUVEC proliferation.Furthermore,ARHGEF15 increased STAT3 phosphorylation in HUVECs.STATTIC treatment prevents ARHGEF15 overexpression-induced STAT3 phosphorylation and HUVEC migration.Conclusion ARHGEF15 increases HUVEC migration by regulating STAT3 signaling.展开更多
The formation of nitrogen-fixing no dules on legume roots requires the coordination of infection by rhizobia at the root epidermis with the initiation of cell divisions in the root cortex.During infection,rhizobia att...The formation of nitrogen-fixing no dules on legume roots requires the coordination of infection by rhizobia at the root epidermis with the initiation of cell divisions in the root cortex.During infection,rhizobia attach to the tip of elongating root hairs which then curl to entrap the rhizobia.However,the mechanism of root hair deformation and curling in response to symbiotic signals is still elusive.Here,we found that small GTPases(MtRac1/MtROP9 and its homologs)are required for root hair development and rhizobial infection in Medicago truncatula.Our results show that the Nod factor receptor LYK3 phosphorylates the guanine nucleotide exchange factor MtRopGEF2 at S73 which is critical for the polar growth of root hairs.In turn,phosphorylated MtRopGEF2 can activate MtRac1.Activated MtRac1 was found to localize at the tips of root hairs and to strongly interact with LYK3 and NFP.Taken together,our results support the hypothesis that MtRac1,LYK3,and NFP form a polarly localized receptor complex that regulates root hair deformation during rhizobial infection.展开更多
基金Sponsored by National Basic Research Program of China (2006CB601203)
文摘Modified mathematical models based on imaginary plane zone method in reheating furnace were developed in which non-gray radiation properties of gas were considered,and the Newton＇s method and the finite difference method were adopted. Effects of productivity,fuel consumption,fuel-air ratio,calorific value of fuel and inserting depth of thermocouple on total heat exchange factor along the length of reheating furnace were investigated. The results show that total heat exchange factor increases with productivity or inserting depth of thermocouple,and it decreases when fuel consumption,fuel-air ratio or calorific value of fuel increases. The results are valuable for dynamical compensation of total heat exchange factor for online control mathematical models in reheating furnace.
文摘BACKGROUND Phosphatidylinositol-3,4,5-trisphosphate dependent Rac exchange factor 1(PREX1)was reported to be overexpressed in some cancers and involved in cancer development,but its expression and significance in gastric cancer remain unclear.AIM To evaluate the expression of PREX1 in gastric cancer and its significance in the development of gastric cancer,especially to evaluate the potential mechanism of PREX1 in gastric cancer.METHODS Bioinformatic analysis was performed in order to examine the expression of PREX1 in gastric cancer.The relationship between the survival rate of gastric cancer patients and PREX1 expression was assessed by Kaplan Meier portal.The Gene Set Enrichment Analysis and the correlation between PREX1 and transforming growth factor(TGF)β1 pathway-related mediators were evaluated by cBioPortal for Cancer Genomics.Western blotting and reverse transcriptase polymerase chain reaction assay were used to test the role of TGFβ1 on the expression of PREX1.Western blotting and dual-luciferase reporter system was used to evaluate the effect of PREX1 on the activation of TGFβ1 pathway.Wound healing and Transwell assay were used to assess the effect of PREX1 on the metastasis activity of gastric cancer cells.RESULTS PREX1 was overexpressed in the gastric tumors,and the expression levels were positively associated with the development of gastric cancer.Also,the high expression of PREX1 revealed poor prognosis,especially for those advanced and specific intestinal gastric cancer patients.PREX1 was closely involved in the positive regulation of cell adhesion and positively correlated with TGFβ1-related mediators.Furthermore,TGFβ1 could induce the expression of PREX1 at both the protein and mRNA level.Also,PREX1 could activate the TGFβ1 pathway.The induced PREX1 could increase the migration and invasion activity of gastric cancer cells.CONCLUSION PREX1 is overexpressed in gastric cancer,and the high level of PREX1 predicts poor prognosis.PREX1 is closely associated with TGFβsignaling and promotes the metastasis of gastric cancer cells.
文摘BACKGROUND Phosphatidylinositol-3,4,5-trisphosphate dependent Rac exchange factor 1(PRex1)was reported to be a risk factor in several cancers,including breast cancer,lung cancer,and melanoma,but its expression and role in hepatocellular carcinoma(HCC)have not yet been fully studied.AIM To explore the expression of P-Rex1 in HCC,and further evaluate its potential application in the diagnosis and prognosis of HCC,especially in hepatitis B virus(HBV)-related patients.METHODS P-Rex1 expression in HCC was evaluated by real-time-quantitative polymerase chain reaction.The expression of P-Rex1 was subjected to correlation analysis with clinical features,such as lymph node invasion,distant metastasis,HBV infection,patient’s age and gender.Receiver operating characteristic analysis was used to examine the potential role of P-Rex1 as a diagnostic biomarker in HCC.Kaplan-Meier analysis was used to determine the association between P-Rex1 expression and overall survival,progression-free survival and relapse-free survival.Bioinformatic analysis was used to validate the clinical findings.RESULTS P-Rex1 expression was significantly increased in HCC tumors than adjacent tissues.The expression of P-Rex1 was higher in HCC patients with lymph node invasion,distant metastasis,HBV infection and positive alpha-fetoprotein,respectively.The receiver operating characteristic analysis showed that P-Rex1 was a diagnostic biomarker with a higher area under the curve value,especially in patients with HBV infection.Survival analysis showed that patients with higher P-Rex1 expression had a favorable survival rate,even in early-stage patients.CONCLUSION P-Rex1 expression was highly increased in HCC,and the expression level of PRex1 was positively correlated with tumor progression.P-Rex1 has a higher efficiency in the diagnosis of HBV-related HCC,and could also be used as a favorable prognostic factor for HCC patients.
基金The National Basic Research Program of China(973 Program)under contract No.2013CB835304the National Marine Public Projects under contract No.201305016+2 种基金the National Natural Science Foundation of China(General Program)under contract No.31601865the Dalian Science and Technology Program under contract No.2013E11SF056the Education Department of the General Scientific Research Project under contract No.L201683651
文摘The Guanine nucleotide exchange factor Vav2（Vav2） is a member of the Vav family that serves as an important regulators for the Rho family of Ras-related GTPases. In the current study, an ortholog（Lj-Vav2） of Vav2 was identified in the lamprey（Lampetra japonica）. To elucidate the phylogenetic relationship of Vav2, the metazoan genome databases were analyzed to mine the ortholog of Vav. It was found that Vav2 genes were only existed in vertebrates and Lj-Vav2 was the original one found in agnathans. The evolutionary dynamics of conserved motifs of Vav2 were explored using combined amino acid sequence as markers, and it is revealed that the Calponin homology（CH） domain, Dbl-homologous（DH） domain, Pleckstrin homology（PH） domain, Cysteine-rich（C1）domains, Src homology 3（SH3） domains and Src homology 2（SH2） domain were conserved throughout the Vav2 gene family in vertebrates during gene evolution. Relative quantitative real-time PCR analysis showed that the LjVav2 was distributed in the heart, kidney, supraneural myeloid body, liver, gill and lymphocyte-like cells. The LjVav2 was found to be expressed in these tissues, and the level of which was upregulated in lymphocyte-like cells after the animal was stimulated with LPS. These results indicated that the Lj-Vav2 might be involved in the immune response of lymphocyte-like cells in lamprey. Meanwhile, our findings provided a foundation for further investigation of the function of Lj-Vav2 in the primary vertebrate.
基金Supported by the National Natural Science Foundation of China (30530060)the State Key Basic Research and Development Plan of China(2007CB108700)the Ministry of Education (111 project numberedB06003)
文摘In flowering plants, male gametes are delivered to female gametophytes by pollen tubes. Although it is important for sexual plant reproduction, little is known about the genetic mechanism that controls pollen germination and pollen tube growth. Here we report the identification and characterization of two novel mutants, gnom-like 2-1 （gnl2-1） and gn12-2 in Arabidopsis thaliana, in which the pollen grains failed to germinate in vitro and in vivo. GNL2 encodes a protein homologous to the adenosine diphosphate-ribosylation factor-guanine nucleotide exchange factors, GNOM and GNL1 that are involved in endosomal recycling and endoplasmic reticulum-Golgi vesicular trafficking. It was prolifically expressed in pollen grains and pollen tubes. The results of the present study suggest that GNL2 plays an important role in pollen germination.
基金supported by the National Natural Science Foundation of China(31400221)the Beijing Advanced Innovation Center for Tree Breeding by Molecular Design+1 种基金the Program for Changjiang Scholars and Innovative Research Team in University(IRT13047)the Fundamental Research Funds for the Central Universities(BLX2012038)
文摘The plant cell wall is an important interface for sensing pathogen attack and activating signaling pathways that promote plant immune responses.THESEUS1(THE1) acts as a sensor of cell wall integrity that controls cell elongation during plant growth.However, no specific role for THE1 in plant defense responses has been reported. Here, we found that THE1 interacts with GUANINE EXCHANGE FACTOR4(GEF4)and that both proteins play regulatory roles in plant resistance to the necrotrophic fungus Botrytis cinerea.Genetic analysis showed that THE1 and GEF4 function in the same genetic pathway to mediate plant defense responses. In addition, using transcriptome analysis, we identified various genes(such as defense-related,secondary metabolite-related, and transcription factor genes) that are likely downstream targets in the THE1-GEF4 signaling pathway. Our results suggest that THE1 functions as an upstream regulator of GEF4 signaling to positively regulate defense responses against B. cinerea in Arabidopsis.
基金Supported by the Energy Policy and Planning Office,Ministry of Energy,Thailand
文摘The article presents an experimental and numerical study on thermal performance enhancement in a constant heatfluxed square-duct inserted diagonally with 45° discrete V-finned tapes(DFT).The experiments were carried out by varying the airflow rate through the tested square duct with DFT inserts for Reynolds number from 4000 to 25000.The effect of the DFT with V-tip pointing upstream at various relative fin heights and pitches on heat transfer and pressure drop characteristics was experimentally investigated.Both the heat transfer and pressure drop were presented in terms of Nusselt number and friction factor respectively.Several V-finned tape characteristics were introduced such as fin- to duct-height ratio or blockage ratio(R_B=e/H = 0.075,0.1,0.15 and 0.2),fin pitch to duct height ratio(R_P= P/H=0.5,1.0,1.5 and 2.0) and fin attack angle,α = 45°.The experimental results reveal that the heat transfer and friction factor values with DFT inserts increase with the increment of R_B but the decrease of R_P.The inserted square-duct at R_B = 0.2 and R_P = 0.5 provides the highest heat transfer and friction factor while the one with R_B= 0.1 and R_P= 1.5 yields the highest thermal performance.Also,a numerical simulation was conducted to investigate the flow structure and heat transfer mechanism inside the tested duct with DFT inserts.
基金supported by the National Natural Science Foundation of China(32072042,31821005,32000370)Ten-Thousand Talents Programs,Fundamental Research Funds for the Central Universities(2662020SKPY006)+1 种基金Wuhan Applied Foundational Frontier Project(2020020601012257)Hubei Hongshan Laboratory(2021hszd005).
文摘Guanine nucleotide exchange factors(GEFs)and guanine nucleotide-dissociation inhibitors(GDIs)regulate small GTPase proteins,which function as molecular switches in various signaling pathways,but their identification and functions in plants are not well understood.Using in-silico analysis and transgenic approaches,respectively,we dissected the evolutionary relationships and functions of all GEF and GDI genes in rice.Intron-exon distribution and phylogenetic analyses identified 30 GEF and 10 GDI genes in rice that shared close evolutionary relationships with other eukaryotes.Tissue-specific expression and co-expression analyses revealed that phylogenetically related genes had similar expression patterns.GEF and GDI genes were highly expressed in panicles,hulls,and stamens.Co-expression network analysis identified panicle and stamen-specific modules of co-expressed genes in both families.Mapping of these genes in known protein interactomes further identified two and one small G-protein sub-networks.A mutant library of GEF and GDI families was constructed by CRISPR knockout of each gene,and their genotypes and phenotypes were confirmed.Phenotype changes occurred with the mutation of only three genes(OsGEF5,OsGDI1,and OsGEF3).OsGEF5 and OsGDI1 single mutants exhibited significantly reduced height and longer and thinner grains,whereas OsGEF3 mutants had reduced grain length compared to the wild type.Haplotype and eGWAS analyses showed that natural variations in the three genes affected gene expression in reproductive tissues that were significantly associated with the phenotypic variation.BiFC assays demonstrated that GDI1 and GEF3 interacted with grain-size protein GS3,pointing to a role of these genes in the regulation of grain size and plant architecture connected to heterotrimeric G-proteins in rice.
基金the National Natural Science Foundation of China to Wang Zonghua （30070030, 30470066）.
文摘MgCdc42 （Cdc42 in Magnaporthe grisea）, with high homology to ScCdc42 （Cdc42 in Saccharomyces cerevisiae）, has been demonstrated to involve in the morphogenesis and infection process. To further understand the signaling network, the putative MgCdc42-interacting proteins were analyzed. ScCdc42-interacting protein sequences were first used to BLAST against the M. grisea genome database to retrieve their corresponding analogs. Subsequently, conserved domains of these proteins were compared and expression patterns of their encoding genes in different MgCdc42 mutation states were analyzed by semiquantitative RT-PCR. All retrieved analogs of ScCdc42-interacting proteins from the M. grisea database have conserved domains as those in S. cerevisiae. Expression of their encoding genes increased in MgCdc42CA mutant and decreased in MgCdc42KO mutant. However, MgBeml, Chin1, and MgGicl in MgCdc42DN mutant had the same expression level as that in the wild type, although MgBem4, MgBoi2, MgCdc24, MgGic2, MgRgal, and Mst20 had decreased expression level, as expected. Overall, it is concluded that there may exist a similar Cdc42 signal pathway in M. grisea as in S. cerevisiae and MgCdc42 plays a key role in the pathway.
基金supported by the grants from the National Natural Science Foundation of China(32201025 to D.T.,32071214 to S.Q.,32470738 to S.Q.,and 32471311 to D.T.)。
文摘Autophagy is a fundamental cellular process,conserved across species from yeast to mammals,that plays a crucial role in maintaining cellular homeostasis.The functionally conserved MON1-CCZ1(MC1)complex serves as a guanine nucleotide exchange factor(GEF)for the RAB GTPase RAB7A and is indispensable for directing RAB7A recruitment to autophagosome or lysosomal membranes.Despite its critical role,the precise molecular mechanism underlying the assembly of the human MON1A-CCZ1(HsMC1)complex and its specific GEF activity towards RAB7A has remained unclear.In this study,we report the high-resolution cryo-electron microscopy(cryo-EM)structure of the HsMC1 GEF domain in a complex with the nucleotide-free RAB7A^(N125I)at 2.85 A resolution.Our structural data demonstrate that engagement with the HsMC1 complex induces marked conformational shifts in the phosphate-binding loop(P-loop)and SwitchⅠ/Ⅱregions of RAB7A.A striking feature of this complex is the direct interaction between the P-loop of RAB7A and CCZ1,a structural detail not previously observed.Furthermore,biochemical assays targeting residues within InterfaceⅠorⅡof the HsMC1-RAB7A complex highlight their critical role in mediating the interaction and suggest a unique mechanism for nucleotide exchange facilitated by the HsMC1 complex.These findings provide novel molecular insights into the functional mechanisms of the HsMC1-RAB7A complex,offering a robust structural framework to inform future investigations into disease-related targets and therapeutic development.
基金Under the auspices of National Natural Science Foundation of China(No.41101080)Shandong Natural Science Foundation of China(No.ZR2014DQ028,ZR2015DM004)
文摘Estuarial saline wetlands have been recognized as a vital role in CO_2 cycling.However,insufficient attention has been paid to estimating CO_2 fluxes from estuarial saline wetlands.In this study,the static chamber-gas chromatography(GC) method was used to quantify CO_2 budget of an estuarial saline reed(Phragmites australis) wetland in Jiaozhou Bay in Qingdao City of Shandong Province,China during the reed growing season(May to October) in 2014.The CO_2 budget study involved net ecosystem CO_2 exchange(NEE),ecosystem respiration(Reco) and gross primary production(GPP).Temporal variation in CO_2 budget and the impact of air/soil temperature,illumination intensity and aboveground biomass exerted on CO_2 budget were analyzed.Results indicated that the wetland was acting as a net sink of 1129.16 g/m^2 during the entire growing season.Moreover,the values of Reco and GPP were 1744.89 g/m^2 and 2874.05 g/m^2,respectively;the ratio of Reco and GPP was 0.61.Diurnal and monthly patterns of CO_2 budget varied significantly during the study period.Reco showed exponential relationships with air temperature and soil temperature at 5 cm,10 cm,20 cm depths,and soil temperature at 5 cm depth was the most crucial influence factor among them.Meanwhile,temperature sensitivity(Q10) of Reco was negatively correlated with soil temperature.Light and temperature exerted strong controls over NEE and GPP.Aboveground biomass over the whole growing season showed non-linear relationships with CO_2 budget,while those during the early and peak growing season showed significant linear relationships with CO_2 budget.This research provides valuable reference for CO_2 exchange in estuarial saline wetland ecosystem.
基金This work was supported by the National Programs for High Technology Research and Development Program(863 Program)(Grant No.2006AA02A316)the National Basic Research Program(973 Program)(Grant Nos.2004CB520801,2006CB910903,2007CB914304,2009CB825501 and 2010CB912301)+1 种基金the Ministry of Science and Technology,National Natural Science Foundation of China(Grant Nos.30721003 and 30870484)the Chinese Academy of Sciences(Grant No.KSCX2-YW-R61).
文摘Eukaryotic translation initiation factor eIF2B,the guanine nucleotide exchange factor(GEF)for eIF2,catalyzes conversion of eIF2·GDP to eIF2·GTP.The eIF2B is composed of five subunits,α,β,γ,δandε,within which theεsubunit is responsible for catalyzing the guanine exchange reaction.Here we present the crystal structure of the C-terminal domain of human eIF2Bε(eIF2Bε-CTD)at 2.0-Åresolution.The structure resembles a HEAT motif and three charge-rich areas on its surface can be identified.When compared to yeast eIF2Bε-CTD,one area involves highly conserved AA boxes while the other two are only partially conserved.In addition,the previously reported mutations in human eIF2Bε-CTD,which are related to the loss of the GEF activity and human VWM disease,have been discussed.Based on the structure,most of such mutations tend to destabilize the HEAT motif.
基金supported by the National Natural Science Foundation of China(Nos.82241030,82171318,82011530024)the State Program of Scientific Research“Natural resources and the Environment”(3.01,2020–2021,Belarus)+1 种基金Academic Promotion Program of Shandong First Medical University(2019QL014)Fund for Laboratory of Translational Medicine in Microvascular Regulation of The First Affiliated Hospital of Shandong First Medical University.
文摘Objective Rho guanine nucleotide exchange factor 15(ARHGEF15)is a member of the RhoGEF family that activates the Rho protein.High ARHGEF15 expression is associated with poor prognosis in patients with pancreatic cancer.Although ARHGEF15 is abundantly expressed in endothelial cells,its detailed functions remain unknown.This study aimed to elucidate the effects of ARHGEF15 on endothelial cells and the underlying molecular mechanisms involved.Methods The ARHGEF15 gene was overexpressed or knocked down in human umbilical vein endothelial cells(HUVECs),and the results were validated via qRT-PCR and Western blotting.CCK8 and MTT assays were used to evaluate cell proliferation.Wound healing and transwell assays were used to assess cell migration.The activation of STAT3 signaling was examined by Western blotting,and STATTIC was used to inhibit STAT3 signaling.Results ARHGEF15 overexpression promoted the migration of HUVECs,and ARHGEF15 knockdown inhibited the migration of HUVECs.Neither the overexpression nor the knockdown of ARHGEF15 affected HUVEC proliferation.Furthermore,ARHGEF15 increased STAT3 phosphorylation in HUVECs.STATTIC treatment prevents ARHGEF15 overexpression-induced STAT3 phosphorylation and HUVEC migration.Conclusion ARHGEF15 increases HUVEC migration by regulating STAT3 signaling.
基金This work was supported by the National Key Research and Development Program of China(2016YFA0500502)the National Science Foundation(31825003,31730103,31870218)+1 种基金the Strategic Priority Research Program"Molecular Mechanism of Plant Growth and Development"of the Chinese Academy of Sciences(XDB27040207)CAS Project for Young Scientists in Basic Research(YSBR-011).
文摘The formation of nitrogen-fixing no dules on legume roots requires the coordination of infection by rhizobia at the root epidermis with the initiation of cell divisions in the root cortex.During infection,rhizobia attach to the tip of elongating root hairs which then curl to entrap the rhizobia.However,the mechanism of root hair deformation and curling in response to symbiotic signals is still elusive.Here,we found that small GTPases(MtRac1/MtROP9 and its homologs)are required for root hair development and rhizobial infection in Medicago truncatula.Our results show that the Nod factor receptor LYK3 phosphorylates the guanine nucleotide exchange factor MtRopGEF2 at S73 which is critical for the polar growth of root hairs.In turn,phosphorylated MtRopGEF2 can activate MtRac1.Activated MtRac1 was found to localize at the tips of root hairs and to strongly interact with LYK3 and NFP.Taken together,our results support the hypothesis that MtRac1,LYK3,and NFP form a polarly localized receptor complex that regulates root hair deformation during rhizobial infection.
