Cdc6 contributes to abrogating the G1 checkpoint under hypoxic conditions in HPV E7 expressing cells

The human papillomavirus (HPV) plays a central role in cervical carcinogenesis and its oncogene E7 is essential in this process. We showed here that E7 abrogated the G1 cell cycle checkpoint under hypoxia and analyzed key cell cycle related proteins for their potential role in this process. To further explore the mechanism by which E7 bypasses hypoxia-induced G1 arrest, we applied a proteomic approach and used mass spectrometry to search for proteins that are differentially expressed in E7 expressing cells under hypoxia. Among differentially expressed proteins identified, Cdc6 is a DNA replication initiation factor and exhibits oncogenic activities when overexpressed. We have recently demonstrated that Cdc6 was required for E7-induced re-replication. Significantly, here we showed that Cdc6 played a role in E7-mediated G1 checkpoint abrogation under hypoxic condition, and the function could possibly be independent from its role in DNA replication initiation. This study uncovered a new function of Cdc6 in regulating cell cycle progression and has important implications in HPV-associated cancers

Role of WDHD1 in Human Papillomavirus-Mediated Oncogenesis Identified by Transcriptional profiling of E7-expressing cells

The E7 oncoprotein of the high-risk human papillomavirus (HPV) plays a major role in HPV-induced carcinogenesis. E7 abrogates the G(1) cell cycle checkpoint and induces genomic instability, but the mechanism is not fully understood. In this study, we performed RNA sequencing (RNA-seq) to characterize the transcriptional profile of keratinocytes expressing HPV 16 (HPV-16) E7. At the transcriptome level, 236 genes were differentially expressed between E7 and vector control cells. A subset of the differentially expressed genes, most of them novel to E7-expressing cells, was further confirmed by real-time PCR. Of interest, the activities of multiple transcription factors were altered in E7-expressing cells. Through bioinformatics analysis, pathways altered in E7-expressing cells were investigated. The upregulated genes were enriched in cell cycle and DNA replication, as well as in the DNA metabolic process, transcription, DNA damage, DNA repair, and nucleotide metabolism. Specifically, we focused our studies on the gene encoding WDHD1 (WD repeat and high mobility group [HMG]-box DNA-binding protein), one of the genes that was upregulated in E7-expressing cells. WDHD1 is a component of the replisome that regulates DNA replication. Recent studies suggest that WDHD1 may also function as a DNA replication initiation factor as well as a G(1) checkpoint regulator. We found that in E7-expressing cells, the steady-state level of WDHD1 protein was increased along with the half-life. Moreover, downregulation of WDHD1 reduced E7-induced G(1) checkpoint abrogation and rereplication, demonstrating a novel function for WDHD1. These studies shed light on mechanisms by which HPV induces genomic instability and have therapeutic implications. IMPORTANCE The high-risk HPV types induce cervical cancer and encode an E7 oncoprotein that plays a major role in HPV-induced carcinogenesis. However, the mechanism by which E7 induces carcinogenesis is not fully understood; specific anti-HPV agents are not available. In this study, we performed RNA-seq to characterize transcriptional profiling of keratinocytes expressing HPV-16 E7 and identified more than 200 genes that were differentially expressed between E7 and vector control cells. Through bioinformatics analysis, pathways altered in E7-expressing cells were identified. Significantly, the WDHD1 gene, one of the genes that is upregulated in E7-expressing cells, was found to play an important role in E7-induced G(1) checkpoint abrogation and rereplication. These studies shed light on mechanisms by which HPV induces genomic instability and have therapeutic implications

Additional stress in soil embankments subjected to a new prestressed reinforcement device

Theoretical solutions were derived to calculate the additional stress/prestress in a newly-developed prestressed embankment (PE), and the diffusion characteristics of the prestress in a PE with a lateral pressure plate (LPP) having width of 0.9 m were clarified using the theoretical solutions and a 3D finite element analysis. The results show that (1) the application of the theoretical solutions requires the net spacing between the LPP and the embankment shoulder is greater than the LPP width; (2) the maximum prestress appears in the upper part of the loading area of a LPP, and the maximum and minimum prestresses present an order of magnitude difference at the shallow depth, but the difference attenuates and the prestress gradually tends to be uniform with increasing depth; (3) the prestress propagates to the core zones that mainly bear the train loads with certain peak stress diffusion angles, and the values for the analyzed case are 50° and 58° in the external regions of the LPP along the slope and longitudinal directions, respectively; and (4) a continuous, effective and relatively uniform prestressing protective layer with a prestress coefficient greater than 0.1 can be formed above the core zones when the LPP spacing is properly designed

Coherent spinor dynamics in a spin-1 Bose condensate

Collisions in a thermal gas are perceived as random or incoherent as a consequence of the large numbers of initial and final quantum states accessible to the system. In a quantum gas, e.g. a Bose-Einstein condensate or a degenerate Fermi gas, the phase space accessible to low energy collisions is so restricted that collisions be-come coherent and reversible. Here, we report the observation of coherent spin-changing collisions in a gas of spin-1 bosons. Starting with condensates occupying two spin states, a condensate in the third spin state is coherently and reversibly created by atomic collisions. The observed dynamics are analogous to Josephson oscillations in weakly connected superconductors and represent a type of matter-wave four-wave mixing. The spin-dependent scattering length is determined from these oscillations to be -1.45(18) Bohr. Finally, we demonstrate coherent control of the evolution of the system by applying differential phase shifts to the spin states using magnetic fields.Comment: 19 pages, 3 figure

Dynamic Response Characteristics of Railway Subgrade Using a Newly-Developed Prestressed Reinforcement Structure: Case Study of a Model Test

Poor subgrade conditions usually induce various subgrade diseases in railways, leading to some adverse influences. An innovative technology that involves installing a prestressed reinforcement structure (PRS) that consists of steel bars and lateral pressure plates (LPP) for subgrade was introduced to improve its stress field and provide compulsive lateral deformation constraints for slope. In this study, an investigation into the dynamic acceleration responses of railway subgrade strengthened according to different PRS schemes was presented using a 1:5 scale model test, aiming to explore the effects of the axle load, the reinforcement pressure, and the loading cycles on the acceleration characteristics of the subgrade. The experimental results showed that (1) after pretension of the steel bar, prestress loss occurred due to the soil creep behavior and group anchor effect, so a moderate amount of over-tension in practices would be necessary; (2) a distinctive periodical behavior of subgrade subjected to the cyclic loads was observed, the horizontal accelerations were generally less than the vertical accelerations at the same measurement heights, and the vibration energy attenuated gradually from the shoulder to the toe along the slope; (3) in the short-term tests, the peak accelerations at all measurement points had a linear correlation with the axle load, and oppositely, it showed an approximately linear decrease with the increasing reinforcement pressure; And (4) in the long-term tests, to simulate the heavy haul wagon with a 35 t axle load, the variation in the effective acceleration with loading cycles under reinforcement pressure 100 kPa initially exhibited a decrease and subsequently tended to be stable, which is apparently less than that without reinforcement pressure. Consequently, it was demonstrated that the PRS itself and increasing reinforcement pressure can effectively mitigate the subgrade vibration, and provide an appropriate alternative to improve the dynamic performance of railway subgrade under the moving train loads

Determination of glyphosate and aminomethylphosphonic acid in soybean samples by high performance liquid chromatography using a novel fluorescent labeling reagent

A highly sensitive pre-column derivatization HPLC method for simultaneous determination of glyphosate (GLYP) and its major metabolite aminomethylphosphonic acid (AMPA) in soybean samples was developed. The analytes were labeled with a novel fluorescent labeling reagent 3,6-dimethoxy-9-phenyl-9H-carbazole-1-sulfonyl chloride (DPCS-Cl) at 70 C for 25 min. The optimized concentration of DPCS-Cl was 25 mg mL À1 and the molar ratio of analytes to DPCS-Cl was 1 : 4.2. The derivatives were separated on a reversed-phase column by gradient elution and were monitored with fluorescence detection at 318 nm (excitation) and 440 nm (emission). The method linearity, calculated for GLYP and AMPA, had a correlation coefficient greater than 0.999. The detection limits for GLYP and AMPA were 0.02 ng mL À1 and 0.01 ng mL À1 (S/N ¼ 3), respectively. In addition, a simple sample pretreatment for the soybean samples was developed to extract GLYP and AMPA. The recovery of extraction was more than 95%. Then, this method gave the detection limits of 0.002 mg kg À1 for GLYP and 0.001 mg kg À1 for AMPA in soybean samples. This HPLC method was applied to the determination of glyphosate and AMPA in soybean samples with its merits of simplicity in pretreatment, rapidity in derivatization, stability of the derivatives and high sensitivity

New Structure for Strengthening Soil Embankments

A new prestressed reinforcement device (PRD) consisting of two lateral pressure plates (LPPs) and a reinforcement bar is developed to strengthen soil embankments by improving the soil confining pressure and providing lateral constraint on embankment slopes. The reinforcement effects of PRDs were demonstrated by investigating the beneficial effects of increasing confining pressure on the soil behavior via the performance of a series of large-scale static and cyclic triaxial tests on a coarse-grained embankment soil. The results show that PRDs can effectively improve the soil shear strength, bearing capacity, ability to resist elastic and plastic deformation, critical dynamic stress, and dynamic shear modulus, and empirical methods were also developed to determine the critical dynamic stress and initial dynamic shear modulus of the embankment soil. Moreover, 3D finite element analyses (FEAs) with an LPP width of 1.2 m were performed to analyze the additional stress field in a prestressed heavy-haul railway embankment. The FEAs showed that the additional stress at a given external distance from the border of an LPP first increased to a maximum value and then gradually decreased with increasing depth; the additional stress was transferred to the zones where the subgrade tends to have higher stresses with peak stress diffusion angles of 34° (slope direction) and 27° (longitudinal direction); and a continuous effective reinforcement zone with a minimum additional stress coefficient of approximately 0.2 was likely to form at the diffusion surface of the train loads, provided that the net spacing of the LPPs was 0.7 m. The reinforcement zone above the diffusion surface of the train loads can act as a protective layer for the zones that tend to have higher stresses. Finally, the advantages and application prospects of PRDs are discussed in detail. The newly developed PRDs may provide a cost-effective alternative for strengthening soil embankments

Silica Microspheres with Fibrous Shells: Synthesis and Application in HPLC

Monodispersed silica spheres with solid core and fibrous shell were successfully synthesized using a biphase reaction. Both the thickness and the pore size of the fibrous shell could be finely tuned by changing the stirring rate during synthesis. When stirring was adjusted from 0 to 800 rpm, the thickness of the shell could be tuned from 13 to 67 nm and the pore size from 5 to 16 nm. By continuously adjusting the stirring rate, fibrous shells with hierarchical pore structure ranged from 10 to 28 nm and thickness up to 200 nm could be obtained in one pot. We demonstrate that fibrous shells with controllable thickness and pore size could be coated on silica cores with diameters from 0.5 to 3 μm while maintaining the monodispersity of the particles. As a result of the unique fibrous structure, the BET surface area could reach ∼233 m² g^–1 even though the shell thickness was less than 150 nm. The core–shell particles were modified with C18, packed, and then used in high-performance liquid chromatography (HPLC) separation, showing separation performance as high as 2.25 × 10⁵ plates m^–1 for naphthalene and back pressure as low as 5.8 MPa. These silica microspheres with fibrous shells are expected to have great potential for practical applications in HPLC