42 research outputs found

    Geometry of the Wiman Pencil, I: Algebro-Geometric Aspects

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    In 1981 W.L. Edge discovered and studied a pencil C\mathcal{C} of highly symmetric genus 66 projective curves with remarkable properties. Edge's work was based on an 1895 paper of A. Wiman. Both papers were written in the satisfying style of 19th century algebraic geometry. In this paper and its sequel [FL], we consider C\mathcal{C} from a more modern, conceptual perspective, whereby explicit equations are reincarnated as geometric objects.Comment: Minor revisions. Now 49 pages, 4 figures. To appear in European Journal of Mathematics, special issue in memory of W.L. Edg

    Thermal Error Modeling Method for a CNC Machine Tool Feed Drive System

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    The disadvantages of the common current thermal error modeling methods for CNC machine tool feed drive systems were analyzed, such as the requirement of many temperature sensors to reach high accuracy and poor applicability of different moving states. A new robust modeling method based on the heat transfer theory is proposed, and the procedure of the thermal tests for a feed drive system is presented. Multiple regression method and robust modeling method based on the heat transfer theory were, respectively, used to establish a thermal error model, and a pointer automatic optimizer was used to optimize the parameters in the robust model. A compensation simulation was conducted under five different moving states using these two modeling methods, and the advantages of the robust modeling method were proved. Finally, the compensation effect of the robust modeling method was verified under a random moving state on a vertical machining center

    Neddylation inhibitor MLN4924 suppresses cilia formation by modulating AKT1

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    Abstract The primary cilium is a microtubule-based sensory organelle. The molecular mechanism that regulates ciliary dynamics remains elusive. Here, we report an unexpected finding that MLN4924, a small molecule inhibitor of NEDD8-activating enzyme (NAE), blocks primary ciliary formation by inhibiting synthesis/assembly and promoting disassembly. This is mainly mediated by MLN4924-induced phosphorylation of AKT1 at Ser473 under serum-starved, ciliary-promoting conditions. Indeed, pharmaceutical inhibition (by MK2206) or genetic depletion (via siRNA) of AKT1 rescues MLN4924 effect, indicating its causal role. Interestingly, pAKT1-Ser473 activity regulates both ciliary synthesis/assembly and disassembly in a MLN4924 dependent manner, whereas pAKT-Thr308 determines the ciliary length in MLN4924-independent but VHL-dependent manner. Finally, MLN4924 inhibits mouse hair regrowth, a process requires ciliogenesis. Collectively, our study demonstrates an unexpected role of a neddylation inhibitor in regulation of ciliogenesis via AKT1, and provides a proof-of-concept for potential utility of MLN4924 in the treatment of human diseases associated with abnormal ciliogenesis.https://deepblue.lib.umich.edu/bitstream/2027.42/148214/1/13238_2019_Article_614.pd

    Subgenomic Stability of Progenitor Genomes During Repeated Allotetraploid Origins of the Same Grass Brachypodium hybridum

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    Both homeologous exchanges and homeologous expression bias are generally found in most allopolyploid species. Whether homeologous exchanges and homeologous expression bias differ between repeated allopolyploid speciation events from the same progenitor species remains unknown. Here, we detected a third independent and recent allotetraploid origin for the model grass Brachypodium hybridum. Our homeologous exchange with replacement analyses indicated the absence of significant homeologous exchanges in any of the three types of wild allotetraploids, supporting the integrity of their progenitor subgenomes and the immediate creation of the amphidiploids. Further homeologous expression bias tests did not uncover significant subgenomic dominance in different tissues and conditions of the allotetraploids. This suggests a balanced expression of homeologs under similar or dissimilar ecological conditions in their natural habitats. We observed that the density of transposons around genes was not associated with the initial establishment of subgenome dominance; rather, this feature is inherited from the progenitor genome. We found that drought response genes were highly induced in the two subgenomes, likely contributing to the local adaptation of this species to arid habitats in the third allotetraploid event. These findings provide evidence for the consistency of subgenomic stability of parental genomes across multiple allopolyploidization events that led to the same species at different periods. Our study emphasizes the importance of selecting closely related progenitor species genomes to accurately assess homeologous exchange with replacement in allopolyploids, thereby avoiding the detection of false homeologous exchanges when using less related progenitor species genomes

    Pyrimidine catabolism is required to prevent the accumulation of 5-methyluridine in RNA

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    5-Methylated cytosine is a frequent modification in eukaryotic RNA and DNA influencing mRNA stability and gene expression. Here we show that free 5-methylcytidine (5mC) and 5-methyl-2′-deoxycytidine are generated from nucleic acid turnover in Arabidopsis thaliana, and elucidate how these cytidines are degraded, which is unclear in eukaryotes. First CYTIDINE DEAMINASE produces 5-methyluridine (5mU) and thymidine which are subsequently hydrolyzed by NUCLEOSIDE HYDROLASE 1 (NSH1) to thymine and ribose or deoxyribose. Interestingly, far more thymine is generated from RNA than from DNA turnover, and most 5mU is directly released from RNA without a 5mC intermediate, since 5-methylated uridine (m5U) is an abundant RNA modification (m5U/U ∼1%) in Arabidopsis. We show that m5U is introduced mainly by tRNA-SPECIFIC METHYLTRANSFERASE 2A and 2B. Genetic disruption of 5mU degradation in the NSH1 mutant causes m5U to occur in mRNA and results in reduced seedling growth, which is aggravated by external 5mU supplementation, also leading to more m5U in all RNA species. Given the similarities between pyrimidine catabolism in plants, mammals and other eukaryotes, we hypothesize that the removal of 5mU is an important function of pyrimidine degradation in many organisms, which in plants serves to protect RNA from stochastic m5U modification

    The Relationship between Gene Polymorphism of miRNAs Regulating FGA and Schizophrenia

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    AIM: To investigate the relationship between the polymorphism of related gene loci of miRNAs regulated fibrinopeptide A and schizophrenia. Lay the foundation for the aetiology of schizophrenia. METHODS: Adapt to the phase match of sex and age case-control study, a total of 513 Chinese Han patients with schizophrenia were selected as the case group, 513 normal healthy persons as a control group. Obtaining SNPs information of the FGA gene by querying the dbSNP database, and reference HapMap database included SNPs site frequency information for screening. The frequency distributions of SNPs were genotyped by iMLDR® SNP detection technology. Two SNPs (pre-hsa-miR-605rs2043556 T>C, pre-hsa-miR-499a/pre-hsa-miR-499brs4909237 T < C) were analyzed to demonstrate their association with susceptibility to schizophrenia. RESULTS: There were no significant differences between patients and controls in genotype and allele distribution of SNPs(rs2043556 and rs4909237)in the precursor region of hsa-miR-605 and pre-hsa-miR-499a/pre-hsa-miR-499b. Their gene-gene interaction, which suggests that the polymorphisms of miRNA genes might not contribute to schizophrenia susceptibility in the Han Chinese population. CONCLUSION: No significant difference existed between schizophrenic patients and controls in SNP (rs2043556 and rs4909237) in the precursor region of hsa-miR-605 and pre-hsa-miR-499a/pre-hsa-miR-499b. There may not regulate FGA gene expression. Thus, hsa-miR-605 and pre-hsa-miR-499a/pre-hsa-miR-499b may not influence the risks of schizophrenia

    Compensation for spindle’s axial thermal growth based on temperature variation on vertical machine tools

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    A new spindle’s axial thermal growth model based on temperature variation is proposed considering the limitations of spindle’s axial thermal growth model based on rotating speed. The model based on temperature variation is thereafter derived, and its mechanism is analyzed. It is found that model based on temperature variation is more robust. In the proposed model, a filtering method for calculating error and the identification process for parameters are also presented. The environmental temperature variation error and the repeatability of thermal growth at a constant rotating speed were investigated using a drilling center. Thereafter, the thermal growths at different rotating speeds were investigated using the same drilling center. Furthermore, the thermal growth with the disturbance of cooler was investigated using a milling center. The comparison of model based on rotating speed and model based on temperature variation is simulated, and the results indicate that the robustness of model based on temperature variation for rotating speeds and disturbance of cooler is stronger than model based on rotating speed. Finally, the experimental verification is carried out
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