13 April 2018, Volume 36 Issue 7

    

Think Tank
Scientifc Comments
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Think Tank
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  Harmonizing conflicts of land multifunction in natural reserves-Qiangtang National Natural Reserve as an example

  XU Zengrang, ZHENG Xin, JIN Mingming

  Science & Technology Review. 2018, 36(7): 8-13. https://doi.org/10.3981/j.issn.1000-7857.2018.07.001

  Abstract ( ) Download PDF ( ) HTML   Knowledge map   Save

  China has made great progress in ecological civilization and there are still problems among natural reserves. Most of the endangered species are restoring and increasing in many natural reserves, and herbivore wildlife compete for forage with livestock and carnivore wildlife injures herders and damages houses and barns. Simultaneously, population and settlement develop and extend to the neighboring area, even into hinterland of natural reserves. Land functions conflict, especially between human and wildlife. It's important to study collisions and harmony strategies between human and wildlife. Taking Qiangtang alpine desert and biodiversity conservation national natural reserve as an example, the paper illustrates the conflicts in the last 40 years between human and wildlife, and then analyzes the drive force of the conflicts. Finally, some advices are put forward:(1) constrain the population and livestock amount in Qiangtang natural reserve and the neighboring area, and concentrate settlements into the region more suitable for human to live via ecological resettlement program; (2) harmonize different government departments such as husbandry and natural conservation, balance multifunctions of land including industry development and biodiversity protection; (3) build the Tibetan plateau national park system for strict protection and rational utilization of natural resources such as wildlife sightseeing etc.
Scientifc Comments
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  The universe on wheelchair: A brief introduction to Stephen Hawking's academic contributions and influences

  CAI Ronggen, CAO Liming, YANG Tao

  Science & Technology Review. 2018, 36(7): 14-19. https://doi.org/10.3981/j.issn.1000-7857.2018.07.002

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  In this article we give a brief introduction of Stephen Hawking's main academic contributions and their influences on related subjects. First, we introduce Hawking's accomplishments in his academic jobs such as classic gravity, black hole thermodynamics and quantum cosmology. Then we introduce his academic influences on other related subjects such as the holographic principle of gravity and the gravitational wave physics.
Special Issues
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  The perception mechanism of the plant branching hormone strigolactone

  YAO Ruifeng, LOU Zhiyong, XIE Daoxin

  Science & Technology Review. 2018, 36(7): 20-25. https://doi.org/10.3981/j.issn.1000-7857.2018.07.003

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  Plant hormones regulate every step of the plant life cycle. Elucidating the perception mechanism of plant hormones by their receptors is crucial for understanding plant growth and development, protecting plant and the associated ecosystem, as well as for enhancing food security worldwide. Plant branching is mainly regulated by the branching hormone strigolactone and related phytohormones. The study on the molecular basis of strigolactone action, especially the perception mechanism, has made important breakthrough in recent years:The strigolactone perception mechanisms in the monocot plant rice, the dicot plant Arabidopsis and the parasitic weed Striga have been systematically elucidated, revolutionarily revealing a non-canonical hormone perception mechanism which is different from the reversible "ligand-receptor" perception mode that has been gradually established during the past century. These findings will provide theoretical guidances for breeding crops with ideal architecture as well as for combating the root parasitic weed. In this short review, we will give a brief introduction to the recent advances in strigolactone perception.
Spescial Issues
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  Histone modification dynamics during mouse pre-implantation development

  LIU Xiaoyu, GAO Shaorong

  Science & Technology Review. 2018, 36(7): 26-32. https://doi.org/10.3981/j.issn.1000-7857.2018.07.004

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  Histone methylation, as an important epigenetic modification, plays a critical role in gene expression regulation as well as in the first cell fate determination during pre-implantation development. Low input new-generation sequencing provides us a reliable method to assess genome-wide histone modification reprogramming with high resolution using a very small number of cells. In this article we review the current advances of histone modification dynamics during pre-implantation development obtained through low-input sequencing technologies. Particularly, we highlight the establishment and dynamic of histone H3K4me3 and H3K27me3 modifications during zygotic genome activation and the first lineage differentiation. These advances have shed light on the mechanisms of epigenetic regulation network controlling early development and differentiation.
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  A new cancer immunotherapy based on cholesterol metabolism modulation

  BAI Yibing, XU Chenqi

  Science & Technology Review. 2018, 36(7): 33-36. https://doi.org/10.3981/j.issn.1000-7857.2018.07.005

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  Immune checkpoint blockade and other cancer immunotherapies have achieved great success in clinic but problems such as low response rate still remain. Cholesterol is a key component of cell membrane, whose cellular metabolism can influence the plasma membrane environment and effector function of T cells. We have found that the anti-tumor immune response of CD8⁺ T cells can be potentiated by modulating cellular cholesterol metabolism. Inhibiting the activity of ACAT1, a key cholesterol esterification enzyme, can upregulate the cholesterol level on CD8⁺ T cell plasma membrane, and significantly enhance the anti-tumor effector function. This finding provides a new method for cancer immunotherapy.
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  Pediatric cataract therapy with endogenous stem cells-mediated lens regeneration

  LIU Yizhi

  Science & Technology Review. 2018, 36(7): 37-42. https://doi.org/10.3981/j.issn.1000-7857.2018.07.006

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  Repair and regeneration of tissues using endogenous stem cells represent an ultimate goal in regenerative medicine. To our knowledge, human lens regeneration has not yet been demonstrated. Currently, the only treatment for cataracts, the leading cause of blindness worldwide, is to extract the cataractous lens and implant an artificial intraocular lens. However, this procedure may pose notable risks of complications. In this paper we isolate lens epithelial stem/progenitor cells (LECs) in mammals and show that Pax6 and Bmi1 are required for LEC renewal. We design a surgical method for removal of cataract that preserves endogenous LECs and achieves functional regeneration of lens in rabbits and macaques, as well as in human infants with cataracts. Our method differs conceptually from the current practice, preserves endogenous LECs and their natural environment maximally, and regenerates lenses with visual function. Our approach demonstrates a novel treatment strategy for cataracts and provides a new paradigm for tissue regeneration using endogenous stem cells.
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  The origin of human V(D)J recombination mechanism

  YAN Xinyu, HUANG Shengfeng, XU Anlong

  Science & Technology Review. 2018, 36(7): 43-47. https://doi.org/10.3981/j.issn.1000-7857.2018.07.007

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  Vertebrate V(D)J recombination is mediated by RAG proteins and plays a core role in the vertebrate adaptive immune system. Thus, the origin of V(D)J recombination mechanism has always been a hot spot of immunology research. In this study, amphioxus is chosen as the model species, which is called "living fossil" of vertebrate ancestor. Based on in-depth bioinformatics analyses of three amphioxus genomes and systematic functional research, the ProtoRAG transposon encoding RAG homologous proteins is found. Functional experiments show that ProtoRAG is an active transposon encoding original RAG1/2-like protein, which not only mediates the transfer of itself but also catalyzes the V(D)J rearrangement in a way similar to RAGs in vertebrates. Thus, ProtoRAG represents a molecular "living fossil" of the long-sought ancestral RAG transposon. These findings provide direct and compelling evidence that V(D)J recombination evolved subsequent to an ancestral transposon, as proposed by Tonegawa in 1979. The results of this study are published in Cell in June 2016 and were considered to be evidence of G.O.D.'s (Generation Of Diversity) miracle.
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  Autistic-like behaviors by MECP2 transgenic monkeys and germline transmission

  QIU Zilong, LI Xiao

  Science & Technology Review. 2018, 36(7): 48-55. https://doi.org/10.3981/j.issn.1000-7857.2018.07.008

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  Autism is a neurological disease with high public concern in recent years. Methyl-CpG binding protein 2(MeCP2) plays an important role in autism for its importance in transcriptional regulation and microRNA processing. Mutations in MeCP2 gene are found in most of patients with Rett syndrome, duplications of MeCP2-containing genomic segments cause the MeCP2 duplication syndrome, which shares core symptoms with autism spectrum disorders. Although MeCP2 transgenic mice has already been reconstructed, it is still difficult to identify autism-like behaviours in the mouse model of MeCP2 overexpression. In this article we report the lentivirus-based transgenic cynomolgus monkeys expressing human MeCP2 in the brain. Genomic integration sites of the transgenes are characterized by a deepsequencing-based method and expression of the MeCP2 transgene is confirmed by Western blotting. This type of transgenic monkeys exhibits autism-like behaviours in action, social and emotional aspects and shows germline transmission of the transgene. These results indicate the feasibility and reliability of using genetically engineered non-human primates to study brain disorders.
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  The molecular basis of Ebola virus entry into host cells

  WANG Han, SONG Jian, Gao George Fu, SHI Yi

  Science & Technology Review. 2018, 36(7): 56-63. https://doi.org/10.3981/j.issn.1000-7857.2018.07.009

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  Belonging to Filoviridae family, Ebola virus is a type of enveloped virus that can cause Ebola hemorrhagic fever in humans and primates. Because of its high mortality rate, Ebola virus now is listed as the most virulent pathogens by the World Health Organization. Since it was first found in 1976, Ebola virus has killed tens of thousands of people in Africa, brought great threat to human life and caused enormous economic losses. Therefore, prevention and control of Ebola virus have always been an important part of scientific researches. However, the understanding of Ebola virus is very limited especially in the cell surface receptors and the membrane fusion mechanism, which has hindered antiviral drug design and development. In this paper, we summarize Ebola virus in terms of taxonomy, morphology, viral proteins and viral life cycle, and highlight the achievements made by George Fu Gao's group in the study of molecular basis of Ebola virus entry into host cells. They include the determination of the crystal structures of NPC1-C and its complex with GPcl, which clarifies the recognition mechanism of Ebola virus and its host cell receptor at atomic level. Furthermore, their results reveal the molecular basis of GPcl/NPC1 interactions, thereby shedding light on the mechanism of Ebola virus membrane fusion, which will guide further development of small antiviral molecules and peptides for prevention and/or treatment of Ebola virus infection.
Reviews
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  Current status and prospects of electrochemical migration research

  YI Pan, DONG Chaofang, XIAO Kui, WEI Dan

  Science & Technology Review. 2018, 36(7): 64-73. https://doi.org/10.3981/j.issn.1000-7857.2018.07.010

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  Currently, electronic components are becoming more integrated and more miniaturized, which substantially increases the sensitivity of electrochemical migration (ECM). In this paper, the current status and prospects of electrochemical migration research are reviewed in terms of research methods, failure mechanism and protection methods. In addition, a newly method that improves the sensitivity of ECM is also provided.
Articles
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  Method of interest points prediction based on customer web temporal behavior trajectory

  CHEN Donglin, XIA Qi, DAI Siguang

  Science & Technology Review. 2018, 36(7): 74-79. https://doi.org/10.3981/j.issn.1000-7857.2018.07.011

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  Interest point is the key to improving the accuracy of e-commerce recommendation under big data environment. However, the existing predictive research ignores the comprehensive impact of various customers' behaviors and time series on interest points. In order to make up this gap, the article sets up a customer Web space and time super network model which involves four subnets:customer, time, behavior and interest point, and establishes the influence factors of behavior. Then, based on similarity of superlink prediction method and the establishment of connectivity matrix, the adjacency matrix is calculated and super triangle judgement is made, so that the most similar super edge and the best prediction results of interest points are obtained. Finally, experiment shows that the precision of interest prediction gets better with the decrease of time accuracy within the allowable range of time error. Compared with the traditional method of label prediction, the prediction accuracy is improved from 56.2% to 74%.
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  System engineering research method for equipment maintenance task allocation and scheduling in wartime

  ZAN Xiang, CHEN Chunliang, ZHANG Shixin, LIU Yan, WU Tonghan

  Science & Technology Review. 2018, 36(7): 80-87. https://doi.org/10.3981/j.issn.1000-7857.2018.07.012

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  Equipment maintenance task allocation and scheduling in wartime is an important part of equipment maintenance to meet the challenge of information warfare. To reflect the characteristics of equipment maintenance task allocation and scheduling, a systemic structure is established, including process dimension, logical dimension and knowledge dimension based on Hall three-dimension structure theory. Five important processes, five basic steps, and related technology and method are defined in the system structure. On this basis, task priority sorting, task allocation and task scheduling are confirmed as the key problems through the basic process of equipment maintenance task allocation and scheduling. And the target, restrain conditions, input conditions, output conditions and research focus are analyzed for each key problem.
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  Fabrication and patterning of graphene oxide ink with direct ink writing

  MA Ying, LIU Lu, AN Boxing, LI Fengyu, DING Dan, LIU Ruping, SONG Yanlin

  Science & Technology Review. 2018, 36(7): 88-94. https://doi.org/10.3981/j.issn.1000-7857.2018.07.013

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  Giant graphene oxide (GGO) with radial size distribution of 30~70 μm is fabricated using the modified Hummers method, and graphene oxide ink is prepared. Through direct ink writing, the optimal printing parameters and patterning of graphene oxide ink are realized. When graphene oxide with a concentration of 15 mg/mL is printed at 70 kPa and 3 mm/s, the printing line is smooth and its morphology is fine and controllable. When the printing line is reduced by 15% hydroiodic acid for 3 h, its reduction degree is the highest and has the best electrical performance, with a conductivity up to 4.40×10⁴ S/m, which is much higher than that of the graphene patterned by the existing printing technology. Patterning of graphene oxide ink on various flexible and non-flexible substrates, such as PET, PDMS, glass and silicon wafers is alao successfully achieved. Reduced graphene oxide pattern can be used as a connecting conductor to realize the integration of LED, which is of great significance for the development of graphene based printed electronic devices.