Evidence for a Negative Correlation between Human Reactive Enamine-Imine Intermediate Deaminase A (RIDA) Activity and Cell Proliferation Rate: Role of Lysine Succinylation of RIDA

Reactive intermediate deaminase (Rid) proteins are enzymes conserved in all domains of life. UK114, a mammalian member of RidA subfamily, has been firstly identified as a component of liver perchloric acid-soluble proteins (L-PSP). Although still poorly defined, several functions have been attributed to the mammalian protein UK114/RIDA, including the reactive intermediate deamination activity. The expression of UK114/RIDA has been observed in some tumors, arousing interest in this protein as an evaluable tumor marker. However, other studies reported a negative correlation between UK114/RIDA expression, tumor differentiation degree and cell proliferation. This work addressed the question of UK114/RIDA expression in human non-tumor HEK293 cell lines and in some human tumor cell lines. Here we reported that human RIDA (hRIDA) was expressed in all the analyzed cell line and subjected to lysine (K-)succinylation. In HEK293, hRIDA K-succinylation was negatively correlated to the cell proliferation rate and was under the control of SIRT5. Moreover, K-succinylation clearly altered hRIDA quantification by immunoblotting, explaining, at least in part, some discrepancies about RIDA expression reported in previous studies. We found that hRIDA was able to deaminate reactive enamine-imine intermediates and that K-succinylation drastically reduced deaminase activity. As predicted by in silico analysis, the observed reduction of deaminase activity has been related to the drastic alterations of hRIDA structure inferred by K-succinylation. The role of hRIDA and the importance of its K-succinylation in cell metabolism, especially in cancer biology, have been discussed.     

矩形窗正交时频空检测算法

针对正交时频空(Orthogonal Time Frequency Space, OTFS)调制系统采用矩形窗函数时,信道矩阵结构复杂导致的鲁棒性差的问题,提出了一种基于时域处理和酉近似消息传递的检测算法。该算法首先添加循环前缀,将时域信道转换为分块对角矩阵;然后应用酉变换和近似消息传递建立迭代检测算法。仿真结果表明,所提检测算法能够在不增加复杂度的条件下有效提升检测精度和鲁棒性,特别是存在信道编码的条件下表现出2 dB的性能增益,使得该算法更适用于杂散多径、高速移动等环境,具有较高的应用价值。     

基于PID控制的自适应媒体播放算法

针对视频播放中因缓冲区下溢带来的抖动问题,提出一种基于PID控制的自适应播放算法。算法结合PID控制和自适应播放算法,根据网络信道状态和缓冲区状态控制视频播放速率,并对播放速率的范围和相邻帧播放速率的突变进行控制,在减少缓冲区下溢概率的同时实现视频的平滑播放。该算法在减小缓冲区下溢概率、实现视频的平滑播放以及减少播放延迟方面均优于固定因子自适应播放算法。     

Comprehensive mutagenesis on yeast cytosine deaminase yields improvements in 5-fluorocytosine toxicity in HT1080 cells

Improved prodrug-activating enzymes have the potential to increase the therapeutic efficacy of gene-directed enzyme prodrug therapy (GDEPT). Yeast cytosine deaminase (yCD) is commonly used to convert the prodrug 5-fluorocytosine (5-FC) to the chemotherapeutic 5-fluorouracil for GDEPT. Mutagenesis studies on yCD aimed at improving its application in GDEPT have been limited to subsets of residues or have sought to improve a single property of the enzyme. We performed comprehensive site-saturation mutagenesis (CSM) on yCD designed to create all 2,983 possible unique protein mutants with a single amino acid substitution. We identified active variants through Escherichia coli genetic complementation and screened these mutants, and combinations thereof, for increased ability to sensitize E. coli and HT1080 fibrosarcoma cells to 5-FC. Several mutants identified in this study showed increased sensitization ability for both E. coli and HT1080 cells indicating that CSM is an effective directed evolution tool for identifying unexpectedly beneficial mutations.     

Effects of Genetically Engineered Stem Cells Expressing Cytosine Deaminase and Interferon-Beta or Carboxyl Esterase on the Growth of LNCaP Prostate Cancer Cells

The risk of prostate cancer has been increasing in men by degrees. To develop a new prostate cancer therapy, we used a stem cell-derived gene directed prodrug enzyme system using human neural stem cells (hNSCs) that have a tumor-tropic effect. These hNSCs were transduced with the therapeutic genes for bacterial cytosine deaminase (CD), alone or in combination with the one encoding human interferon-beta (IFN-β) or rabbit carboxyl esterase (CE) to generate HB1.F3.CD, HB1.F3.CD.IFN-β, and HB1.F3.CE cells, respectively. CD enzyme can convert the prodrug 5-fluorocytosine (5-FC) into the activated form 5-fluorouracil (5-FU). In addition, CE enzyme can convert the prodrug CPT-11 into a toxic agent, SN-38. In our study, the human stem cells were found to migrate toward LNCaP human prostate cancer cells rather than primary cells. This phenomenon may be due to interactions between chemoattractant ligands and receptors, such as VEGF/VEGFR2 and SCF/c-Kit, expressed as cancer and stem cells, respectively. The HB1.F3.CE, HB.F3.CD, or HB1.F3.CD.IFN-β cells significantly reduced the LNCaP cell viability in the presence of the prodrugs 5-FC or CPT-11. These results indicate that stem cells expressing therapeutic genes can be used to develop a new strategy for selectively treating human prostate cancer.     

超重力强化AMP-PZ复合溶液脱碳技术及表观动力学

为提高工业上火电厂乙醇胺（MEA）吸收塔脱碳工艺中脱碳率和反应速率,提出了超重力技术耦合2-氨基-2-甲基-1-丙醇-对二氮己环（AMP-PZ）混合胺脱碳方法。正交实验表明：不同操作参数对脱碳率的影响显著性大小依次为：超重力因子、气液比、吸收剂质量浓度、主吸收剂含量、温度;最佳操作条件为：超重力因子为60,气液比为15,吸收剂质量分数为25%,主吸收剂质量分数为60%,温度为25℃,CO₂脱除率可达97.16%。相对传统的乙醇胺（MEA）吸收塔法,CO₂脱除率提高了7.16%。相同操作条件下,旋转填料床的脱碳反应速率常数比曝气反应装置高一倍。建立了超重力场中AMP-PZ脱碳表观动力学模型,不同操作参数对反应速率常数的显著性影响大小依次为：超重力因子>气液比>吸收剂质量浓度。     

Dynamic Expression,Differential Regulation and Functional Diversity of the CNGC Family Genes in Cotton

Cyclic nucleotide-gated channels (CNGCs) constitute a family of non-selective cation channels that are primarily permeable to Ca²⁺ and activated by the direct binding of cyclic nucleotides (i.e., cAMP and cGMP) to mediate cellular signaling, both in animals and plants. Until now, our understanding of CNGCs in cotton (Gossypium spp.) remains poorly addressed. In the present study, we have identified 40, 41, 20, 20, and 20 CNGC genes in G. hirsutum, G. barbadense, G. herbaceum, G. arboreum, and G. raimondii, respectively, and demonstrated characteristics of the phylogenetic relationships, gene structures, chromosomal localization, gene duplication, and synteny. Further investigation of CNGC genes in G. hirsutum, named GhCNGC1-40, indicated that they are not only extensively expressed in various tissues and at different developmental stages, but also display diverse expression patterns in response to hormones (abscisic acid, salicylic acid, methyl jasmonate, ethylene), abiotic (salt stress) and biotic (Verticillium dahlia infection) stimuli, which conform with a variety of cis-acting regulatory elements residing in the promoter regions; moreover, a set of GhCNGCs are responsive to cAMP signaling during cotton fiber development. Protein–protein interactions supported the functional aspects of GhCNGCs in plant growth, development, and stress responses. Accordingly, the silencing of the homoeologous gene pair GhCNGC1&18 and GhCNGC12&31 impaired plant growth and development; however, GhCNGC1&18-silenced plants enhanced Verticillium wilt resistance and salt tolerance, whereas GhCNGC12&31-silenced plants had opposite effects. Together, these results unveiled the dynamic expression, differential regulation, and functional diversity of the CNGC family genes in cotton. The present work has laid the foundation for further studies and the utilization of CNGCs in cotton genetic improvement.     

Clean post-processing of 2-amino-1-propanol sulphate by bipolar membrane electrodialysis for industrial processing of 2-amino-1-propanol

2-Amino-1-propanol (AMP) is a key intermediate compound in the production of antibiotics, with increasing demand in industry. In this study, we propose a newly designed bipolar membrane electrodialysis (BMED) system with a novel three-compartment configuration for the processing of AMP from the AMP sulphate solution. The operational parameters were investigated for optimizing the performance of this novel BMED stack, compared to the traditional two-compartment BMED stack in the pilot scale experiment. The experimental results indicate that this novel type of BMED stack offers a better performance for AMP processing than the conventional two-compartment BMED stack. The optimum performance was observed at the current density ranging from 40 to 60 mA cm⁻² and a spacer thickness of 0.70 mm. The corresponding current efficiency and energy consumption reached up to 53.4% and 3.135 kWh kg⁻¹, respectively. The two-compartment BMED stack was found to have a low current efficiency (39.8%) and a high energy consumption (3.864 kWh kg⁻¹). Pilot-scale experiments for an industrial application of this novel BMED stack have been applied, demonstrating that the BMED process is feasible and economically alternative for AMP purification in the industry.     

微机控制集成运放参数的自动测试

TP—801控制集成运放参数的自动测试系统具有自动测试、自动分档、计数、显示、打印等功能。速度快、结构简单、测试简便、可靠与成本低是系统的主要特点。本文介绍了硬件框图、软件结构和主程序流程图。通过介绍一个测试过程、调试与整定方法,简述计算方法、测试范围与测试精度等问题。     

Effect of gamma-irradiation on flavour 5′-nucleotides,tyrosine, and phenylalanine in mushrooms (Agaricus bisporus)

The impact of gamma-irradiation on 5′-nucleotides and on the free amino acids tyrosine and phenylalanine in fresh mushrooms was studied. After irradiation the samples were freeze-dried to avoid enzyme induced chemical changes. Three 5′-nucleotides could be detected using HPLC–UV and LC–ESI-MS: adenosine 5′-monophosphate (AMP), guanosine 5′-monophosphate (GMP) and guanosine 5′-diphosphate (GDP). Irradiation significantly reduced (p = 0.05) the GDP concentration (22%). AMP showed a marked reduction (46%) only at 5 kGy. GMP, tyrosine, and phenylalanine were not affected by gamma-irradiation.