bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic scan paths investigations under manual and highly automated driving
Authors: Navarro Jordan , Lappi Otto , Osiurak François , Hernout Emma , Gabaude Catherine , Reynaud Emanuelle
Published: February 2021

Active visual scanning of the scene is a key task-element in all forms of human locomotion. In the field of driving, steering (lateral control) and speed adjustments (longitudinal control) models are largely based on drivers’ visual inputs. Despite knowledge gained on gaze behaviour behind the wheel, our understanding of the sequential aspects of the gaze strategies that actively sample that input remains restricted. Here, we apply scan path analysis to investigate sequences of visual scanning in manual and highly automated simulated driving. Five stereotypical visual sequences were identified under manual driving: forward polling (i.e. far road explorations), guidance, backwards polling (i.e. near road explorations), scenery and speed monitoring scan paths. Previously undocumented backwards polling scan paths were the most frequent. Under highly automated driving backwards polling scan paths relative frequency decreased, guidance scan paths relative frequency increased, and automation supervision specific scan paths appeared. The results shed new light on the gaze patterns engaged while driving. Methodological and empirical questions for future studies are discussed.
Biomimetic hydrogels designed for cartilage tissue engineering
Authors: Ngadimin Kresanti D. , Stokes Alexander , Gentile Piergiorgio , Ferreira Ana M.
Published: February 2021

Cartilage-like hydrogels based on materials like gelatin, chondroitin sulfate, hyaluronic acid and polyethylene glycol are reviewed and contrasted, revealing existing limitations and challenges on biomimetic hydrogels for cartilage regeneration.
Pt–Pd bimetallic effect in PtxPd1−x/(Ce,Zr,La)O2 catalysts for NOx, HC and CO elimination
Authors: Wang Ting , Chen Kai , Zhou Renxian
Published: February 2021

The bimetallic catalysts show the alloy structure and the surplus precious metals presented as isolated PMOx species.
Constructing CuNi dual active sites on ZnIn2S4 for highly photocatalytic hydrogen evolution
Authors: Jin Jingyi , Cao Yanren , Feng Ting , Li Yanxin , Wang Ruonan , Zhao Kaili , Wang Wei , Dong Bohua , Cao Lixin
Published: February 2021

Novel CuNi bimetal-modified ZnIn2S4 photocatalysts with enhanced photocatalytic hydrogen evolution performance have been explored. The possible mechanism of the synergistic effect and spillover effect between Cu and Ni were proposed.
Water quality changes during the first meter of managed aquifer recharge
Authors: Hägg Kristofer , Li Jing , Heibati Masoumeh , Murphy Kathleen R. , Paul Catherine J. , Persson Kenneth M.
Published: February 2021

The direct sampling method revealed the high treatment capacity of the unsaturated zone and the significant impact of infiltration basin management on microbial communities in managed aquifer recharge (MAR).
Negative X-ray expansion in cadmium cyanide
Authors: Coates Chloe S. , Murray Claire A. , Boström Hanna L. B. , Reynolds Emily M. , Goodwin Andrew L.
Published: February 2021

X-ray radiation induced unit-cell contraction and phase transition selection in the negative thermal expansion material cadmium cyanide.
The metabolomic analysis of five Mentha species: cytotoxicity, anti-Helicobacter assessment, and the development of polymeric micelles for enhancing the anti-Helicobacter activity
Authors: Bakr Riham O. , Tawfike Ahmed , El-Gizawy Heba A. , Tawfik Nashwa , Abdelmohsen Usama Ramadan , Abdelwahab Miada F. , Alshareef Walaa A. , Fayez Sahar M. , El-Mancy Shereen M. S. , El-Fishawy Ahlam M. , Abdelkawy Mostafa A. , Fayed Marwa A. A.
Published: February 2021

Mentha species are medicinally used worldwide and remain attractive for research due to the diversity of their phytoconstituents and large therapeutic indices for various ailments.
Electrochemically dealloyed nanoporous Fe40Ni20Co20P15C5 metallic glass for efficient and stable electrocatalytic hydrogen and oxygen generation
Authors: Aneeshkumar K. S. , Tseng Jo-chi , Liu Xiaodi , Tian Jinsen , Diao Dongfeng , Shen Jun
Published: February 2021

The anion exchange membrane (AEM) in fuel cells requires new, stable, and improved electrocatalysts for large scale commercial production of hydrogen fuel for efficient energy conversion.
A light-up fluorescence resonance energy transfer magnetic aptamer-sensor for ultra-sensitive lung cancer exosome detection
Authors: Zhu Nanhang , Li Guohao , Zhou Juan , Zhang Yujia , Kang Ke , Ying Binwu , Yi Qiangying , Wu Yao
Published: February 2021

The light-up magnetic aptamer-sensor Fe3O4@Au for ultra-sensitive lung cancer exosome detection based on fluorescence resonance energy transfer.
Black holes
Authors: Rovelli Carlo
Published: February 2021

They are out there in the sky in huge numbers. They are the most astonishing objects in the universe. Their existence was predicted and understood before we detected them. They behave precisely as the theory predicted. Yet, we do not know what happens at their center, nor in their future. But this confusion is our key towards what we most lack in fundamental physics: understanding quantum gravity.
Effects and mechanisms of LES and DDES method on airfoil self-noise prediction at low to moderate Reynolds numbers
Authors: Chen Nanshu , Liu Hanru , Liu Qian , Zhao Xingyu , Wang Yangang
Published: February 2021

The Large Eddy Simulation (LES) method and Delayed Detached Eddy Simulation (DDES) method combined with the Ffowcs Williams and Hawkings (FW–H) analogy are used to predict the self-noise of NACA 65(12)-10 airfoil at low to moderate Reynolds numbers. The computational results have been validated through the comparison with experimental data and NAFNoise predictive data. The results indicate that both LES and DDES methods can output correct sound pressure level (SPL) spectra at a Reynolds number of 2 × 105, but only the LES method is capable of providing reasonable SPL spectra at a Reynolds number of 5 × 105, which the DDES method has failed to do. The broadband noise below 10 kHz obtained from the DDES method is lower than that from NAFNoise prediction by up to 50 dB. Further analysis shows that the DDES method fails to capture the separation and reattachment on the suction side near the trailing edge. Besides, the magnitude of pressure fluctuation on the airfoil surface obtained from the DDES method is far smaller than that from the LES method, providing incorrect acoustic source information for the FW–H equation. In the near-wall region for the DDES case, the Reynolds-averaged Navier–Stokes method is used to compute the unsteady flow field, providing too large viscosity and too small Reynolds stress near the airfoil surface, which makes it difficult to capture the influence of small-scale eddies in the flow field. The characteristics of the DDES method above could cause errors in simulating the unsteady flow field at a Reynolds number of 105 range. On the contrary, the LES method could give better prediction of broadband noise under different incoming flow conditions.
Some optical soliton solutions to the perturbed nonlinear Schrödinger equation by modified Khater method
Authors: Khater Mostafa M. A. , Anwar Sadia , Tariq Kalim U. , Mohamed Mohamed S.
Published: February 2021

This paper investigates the analytical solutions of the perturbed nonlinear Schrödinger equation through the modified Khater method. This method is considered one of the most recent accurate analytical schemes in nonlinear evolution equations where it obtained many distinct forms of solutions of the considered model. The investigated model in this paper is an icon in quantum fields where it describes the wave function or state function of a quantum-mechanical system. The physical characterization of some obtained solutions in our study is explained through sketching them in two- and three-dimensional contour plots. The novelty of our study is clear by showing the matching between our solutions and those that have been constructed in previously published papers.
Magnetic Barkhausen noise: A simulation tool
Authors: Fagan P. , Ducharne B. , Daniel L. , Skarlatos A.
Published: February 2021

Non-destructive magnetic controls are increasing in the industrial field. In this domain, the expectation for simulation tools able to anticipate the magnetic signature, improve the understanding and avoid fastidious and uncertain experimental pre-characterizations is high. Among different methods, the magnetic Barkhausen noise (MBN) control is one of the most popular. MBN raw signal is stochastic, not reproducible, and complex to exploit. MBNenergy, which is obtained by integrating the square of the MBN voltage signal with respect to the time axis is a much more stable indicator. Although the so-called MBNenergy is not, strictly speaking, an energy, it is connected to the domain wall motions and to their kinetic energy. By plotting MBNenergy as a function of H (the tangent surface excitation field), hysteresis cycles are observed. After a rescaling step, B(H) and MBNenergy(H) hysteresis cycles can be compared. They look similar for materials with high magnetocrystalline anisotropy (i.e. when the domain wall contribution is dominant over the magnetization rotation one during the magnetization process). In this study, a multiscale model is used to simulate a virtual anhysteretic behavior of a ferromagnetic steel with a magnetization process limited to the domain wall contribution. By using this anhysteretic contribution in the Jiles-Atherton model and running an inverse procedure, a MBN envelop can be obtained. By modulating the amplitude of an alternating, high frequency signal using this envelop, an accurate simulation of the raw Barkhausen noise is obtained.
Design of high-speed permanent magnet synchronous machines considering thermal demagnetization and mechanical characteristic of permanent magnet
Authors: Bang Tae-Kyoung , Shin Kyung-Hun , Lee Jeong-In , Woo Jong-Hyeon , Cho Han-Wook , Choi Jang-Young
Published: February 2021

This paper presents the design for a high-speed permanent magnet synchronous machine (PMSMs) considering the demagnetization and mechanical characteristics of rare-earth magnets based on the operating temperature. The TRV equation and plane stress analytical method are considered for the temperature, the rotor size is derived from the analysis results of the sleeve thickness, and the stator is designed on the basis of the results of the electromagnetic analysis method. The B–H curve of the permanent magnet (PM) changes with its operating temperature; thus, a thermal demagnetization analysis is conducted to verify the irreversible demagnetization caused by the operating temperature and armature reaction field using electromagnetic finite element method (FEM). It is necessary to consider the irreversible demagnetization with the operating temperature because it can decrease the electromagnetic performance. Therefore, the electromagnetic characteristics of high-speed machines using rare-earth PMs are analyzed to confirm irreversible demagnetization. The validity of the proposed design is confirmed via comparative verifications with the measured results from prototype models.
Inducible heat shock protein A1A (HSPA1A) is markedly expressed in rat myometrium by labour and secreted via myometrial cell-derived extracellular vesicles
Authors: Russell M. F. , Bailey G. C. , Miskiewicz E. I. , MacPhee D. J.
Published: February 2021

The myometrium goes through physiological, cellular and molecular alterations during gestation that necessitate effective cellular proteostasis. Inducible heat shock protein A1A (HSPA1A) is a member of the 70-kDa heat shock protein A (HSPA) family, which acts as a chaperone to regulate proteostasis; however, HSPA1A also participates as a cytokine in inflammatory regulation, leading to its designation as a chaperokine. This study examined the spatiotemporal expression of HSPA1A protein in the rat myometrium throughout gestation and assessed whether it is secreted as cargo of myometrial cell-derived extracellular vesicles (EVs). Immunoblot analysis demonstrated that HSPA1A expression was markedly elevated during late pregnancy and labour and increased by uterine distension. Myometrial HSPA1A expression insitu increased in myocytes of longitudinal and circular muscle layers from Day 19 through to postpartum, specifically in the cytoplasm and nuclei of myocytes from both muscle layers, but frequently detectable just outside myocyte membranes. Scanning electron microscopy examination of samples isolated from hTERT-HM cell-conditioned culture medium, using EV isolation spin columns, confirmed the presence of EVs. EV lysates contained HSPA8, HSPA1A and the EV markers apoptosis-linked gene 2-interacting protein X (Alix), the tetraspanin cluster of differentiation 63 (CD63), tumour susceptibility gene 101 (TSG101) and HSP90, but not the endoplasmic reticulum protein calnexin. These results indicate that HSPA1A may act as a chaperokine in the myometrium during pregnancy.
Collaborative Optimization for Location-Inventory Problem of Commercial Vehicle Distribution Network
Authors: Peng Wanying , Qin Lu
Published: February 2021

This paper studies a bi-level programming model addressing the location-inventory problem which can determine the location of distribution centers and the inventory strategy of distribution centers and stores at the same time. In the location-inventory joint decision model, the order quantity is a continuous decision variable associating the upper and lower models and the remaining decision variables are 0-1 variables. In this paper, a branch and bound method is proposed and the SCIP solver is used to solve the bi-level mixed integer non-linear programming problem. The results show that collaborative optimization can save more costs than the one-by- one optimization method and that the optimal solution has better stability under the condition of demand fluctuation and satisfies the optimal allocation of important customers.
Study on color pavement layout of expressway service area
Authors: Jin Fei
Published: February 2021

In order to solve the existing problems of highway service area color pavement layout. According to the demand and characteristics of expressway service area, this paper analyzes the psychological effect of color, and puts forward the functional demand of color pavement in service area. The layout principle and method of color pavement in service area are expounded. The results can provide reference for the color pavement design of expressway service area.
Passenger Flow Control Method for Network-Wide Operation of Urban Rail Transit System: a case study in Guangzhou
Authors: Zhang Zhe , Huang Zhaohong
Published: February 2021

A passenger flow control method for network-wide operation of urban rail transit system is proposed in this paper. In order to find a better trade-off between the delayed time and the increasing number of controlled passengers, the objective function of passenger flow control is formulated based on the problem description. The constraints about the passenger behaviour and capacity limitation are described and the model is formulated successfully. Finally, the proposed method is applied to control the passenger flow of GuangZhou Metro Line 1. The comparison results show that the proposed control model can be used to produce the optimal control plan.
Signal Coordination Control Based on Comprehensive Correlation Degree
Authors: Wen Ling , Dong Baotian , Li Pengcheng , Yan An
Published: February 2021

The correlation degree between nodes of urban traffic network is the basis of sub-area division, and the signal coordination control in sub-area is very effective to improve the traffic efficiency of road network. In this paper, based on the study of unsaturated traffic state, the paper first analyzes the shortcomings of the existing correlation degree model, and constructs a comprehensive correlation degree model to measure the relationship between the two nodes by considering the factors of section spacing, section flow, signal period, traffic flow dispersion and queue length. Through VISSIM simulation experiment, the examples of 15 sections of 10 nodes are compared with the classical Whitson model and the merging index. The sub-region based on the DBSCAN algorithm is more close to reality, which can provide a good basis for the signal coordination strategy.
Research on Ship Route Planning Method Based on Neural Network Wave Data Forecast
Authors: Jin Xin , Xiong Junting , Gu Dongliang , Yi Chengtao , Jiang Yongxin
Published: February 2021

Route design is an indispensable skill for ships and navigators. However, in actual work, most of the current route design still lies in manually reading port information and other graphic materials, and then revising the sailing plan in conjunction with the weather forecast. On the one hand, this method is not accurate enough, and the graphics and text data are not sufficiently real-time. On the other hand, this method has the disadvantages of being cumbersome and labor-intensive. In response to the above problems, this article combines the actual data set of ICOAD, applies the neural network model, and uses the A* algorithm to plan the route, which provides a reference for the application of artificial intelligence to ship route planning.
The Impacts of Warning Release Time and Speed Limit on Driving Behaviour and Pedestrian-Vehicle Collision Rate on Side-parking Road
Authors: Miao Yiming , Yan Xuedong
Published: February 2021

As we all know, pedestrian-vehicle collisions would cause serious damage to us, especially those caused by blind spots. This study focused on collisions happen in the side- parking road, using a driving simulator to design scenarios. After finishing the experiment, we selected some variables to describe the driver’s driving behaviour, including brake reaction time, warning-to-brake time, and maximum deceleration. To verify the effectiveness of the audio warning system, the collision rate was also discussed. It was found that warning release time has significant effects with all the variables, and gender has significant effects with brake reaction time and warning-to-brake time, while the speed limit only influences maximum deceleration. Collision rate was affected by speed limit and warning release time, which decreased with the increase of speed limit and the late release of warning. It is recommended to set the warning release time to 4s before the collision. On the other hand, it is necessary to select a proper speed limit on the side-parking roads, and it is better to set it under 30km/h to reduce the probability of pedestrian-vehicle collision.
Online Car-hailing Service Quality Evaluation Based on BP Neural Network
Authors: Wang Mingzhi , Wu Xianyu
Published: February 2021

In order to reduce the subjectivity and make sure the online car-hailing evaluation results more authentic and credible, an evaluation index system is constructed from five dimensions of the safety, cost, time, reliability and empathetic, and then a BP neural network model is proposed to solve it. Through the supervised model training of SP survey data, the maximum error between the network output and the actual results no more than 3.68%, which can meet the requirements of online car-hailing service quality evaluation. Finally, a mathematical statistical analysis method is proposed to comprehensive evaluate the online car-hailing service quality. The results show that the evaluation index system is scientific and reasonable, and the model can effectively improve the objectively of the evaluation results and reflect the quality level of online car-hailing service.
Research on the Application of PPP + EPC Mode in Financing of Intercity Railway Projects
Authors: Renxu  , Li Yaping
Published: February 2021

Through the analysis of the current situation of intercity railway project financing, this paper concludes that the demand of funds for intercity railway construction is huge, and it is still mainly debt financing, which leads to the huge financial pressure of local government. In order to alleviate the financial pressure and realize the real equity financing of intercity railway projects, this paper proposes to use “PPP + EPC“ mode to finance. On the one hand, this mode can optimize the whole process management of the project; on the other hand, it can optimize the risk management and control in the project cooperation period, meet the risk return requirements of stakeholders, and promote the sustainable development of intercity railway projects.
Research on seismic fragility analysis of regular bridges based on response spectrum analysis method
Authors: Yi Hangyu , Zhang Shengjie , Zhao Fan , Min Guangyun
Published: February 2021

In this paper, the incremental dynamic analysis (IDA) of a real bridge is carried out by using the nonlinear time-history analysis method and the response spectrum analysis method respectively, and the results of structural response under different earthquake intensity are obtained. Ductility coefficient is used for damage index, and the damage probability of the structure in different damage state is obtained by using logarithmic demand-capacity ratio, and then the seismic fragility curves of the structure are established. To improve the precision of fragility curve of major damage state and failure state by modifying the fitting function is also studied. The results show that the simple linear elastic method is reliable for calculating the seismic response of regular bridges. The seismic response calculated by the response spectrum analysis method could be used as the demand for establishing the fragility curves of regular bridge.
Seismic Response Analysis of Cable-stayed Bridges with Cable Forces Optimized Parameters based on a New Type of Strongly Sub-feasible SQP Method
Authors: Yin Xun-qiang , Zhao Wen-yan , Qiu Xiao-tong , Wang Gui-xuan
Published: February 2021

A new type of strongly sub-feasible SQP (Strong Quadratic Programming) method is used to establish a nonlinear model to realize the automatic search of the rational cable force of the cable-stayed bridge. The objective function is established based on the stress and displacement of the main girder and the bridge tower. The cable force of the stay cable is the design variable, the stress and displacement of the main girder and the bridge tower are the constraints, and the numerical model of the earthquake force is analyzed under different cable loading conditions. The results show that the new type of strongly sub-feasible SQP method is suitable for the complicated cable force optimized parameters of large-scale cable-stayed bridges, the calculated results are in good agreement with the designed cable force, and the bending moment of the main beam in the bridge state is uniform. The main tower is close to the axial compression force, and structural deformation is much smaller than the specification limits. Under the excitation of earthquake, the optimized cable force can effectively improve the uneven distribution of bending moment of the main beam, limit the longitudinal mid-span deformation and the lateral deformation of the main tower, so that the whole structure is safer in the earthquake.
Study on the mechanical properties and application prospects of the traditional and modern connection of wood structure
Authors: Li Lidan , Zhou Jianying
Published: February 2021

Based on the connection status of traditional wood structure nodes in southeast Guizhou, this paper analyzes the structural performance of traditional and modern connection methods of wood structure buildings, and analyzes the mechanical performance and deformation mechanism of the structure through basic traditional wood structure mechanical tests; Analyze the advantages and disadvantages of different connection methods, summarize the improvement ideas of node connection of residential wood structure buildings; compare traditional and modern wood structure systems, analyze the seismic performance of the structure; provide a reasonable reference for wood structure design. Further realize the industrialization and standardization of regional wood structures.
Research on Mechanical Properties and Microstructures of Composite Wall Panels Made of High-Performance Fiber Reinforced Cement-based Composites
Authors: Cheng Baojun , Kang Shengrong , Ma Pengfei , Yang Wen , Shi Boyuan
Published: February 2021

A new-type composite wall panel was designed using the high-performance fiber reinforced cement-based composite and foam concrete, and then their mechanical properties, phase composition and microstructure were investigated. The results show that the composite wall panel is of superior overall mechanical properties, which are ascribed to the high-performance fiber reinforced cement-based composite, where the longitudinal compressive strength, the main phase compositions of the high-performance fiber reinforced cement-based composite are CaCO3, Ca (OH)2, ettringite and C-S-H.
Creep behavior of steel bonded reinforced concrete members under small eccentric compression
Authors: Cao Jian , Pan Xinpeng , Zeng Lingyun , Zeng Jingqi
Published: February 2021

In this paper, the creep behavior of steel bonded reinforced concrete members under small eccentric compression is studied. Firstly, based on the existing mechanical characteristics of concrete under multi axial stress state, the stress-strain relationship of steel bonded small eccentric concrete is theoretically deduced and analyzed by considering the reduction coefficient of hoop force. Secondly, according to the creep characteristics of confined core concrete, combined with the existing concrete creep model and the analysis of its influencing factors, the influence of sticking steel on the creep of small eccentric reinforced concrete compression members is discussed. The corresponding creep calculation formula is established. Finally, the existing experimental data are used to verify the proposed formula, and its applicability is analyzed.
Review of soft rock weathered material for subgrade filling
Authors: De-yong Wang , Jun-long Hu , Jing Wang , Shang-hui Gao
Published: February 2021

With the continuous construction and development of Chinese infrastructure, more and higher requirements are imposed on the construction of expressway engineering. The construction of mountainous expressway has been gradually transformed from winding mountain to bridging and digging tunnels. Various forms of subgrade such as high filling and deep cutting, half filling and half cutting are unavoidable. The huge demand for roadbed filling and the inconvenience of transportation conditions have caused extreme costs for external materials. On the other hand, tunnel excavation brings a large amount of soft rock abandoned slag. If soft rock abandoned slag can be used for subgrade filling, it will not only help avoid resource waste, but also help reduce environmental damage. This paper introduces progress of researches at home and abroad on engineering properties, particle composition and distribution characteristics, CBR, compaction characteristics, etc. of soft rock, as well as the evaluation criteria and applicability of soft rock as subgrade filler in detail.
The effects of the post-annealing with a Zn cap on the structural and electrical properties of sol-gel derived MgxZn1−xO films
Authors: Abe Koji , Morimoto Yasuhiro
Published: February 2021

Structural and electrical properties of Al-doped MgxZn1−xO films were improved by post-annealing with supplying Zn vapor. The Al-doped MgxZn1−xO films were deposited on glass substrates by a sol-gel method. The substrates were dip-coated with a precursor solution and were dried on a hotplate at 270 °C for 10 min. This dip-coating and drying process was repeated 10 times, and the Al-doped MgxZn1−xO films were obtained after calcination in air at 500 °C for 1 h. The as-grown films were post-annealed in H2 at 400 °C for 20 min. To supply zinc vapor, a glass slide with a thermally evaporated Zn layer (Zn cap) was put on the sample surface during the post-annealing. The as-grown films had the wurtzite structure with the c-axis perpendicular to the substrate surface, but the intensity of the (002) diffraction peak decreased with increasing Mg content (x). The crystallinity of the films was improved after the post-annealing with a Zn cap, which was observed when x was below 0.1. The resistivity and carrier concentration of the film (x = 0.1) after the post-annealing with a Zn cap was 6.0 × 10−3 Ωcm and 5.7 × 1019 cm−3, respectively. On the other hand, the resistivity of the film (x = 0.1) after the post-annealing without a Zn cap was 6.6 × 102 Ωcm. Transmittance spectra in the visible range were not affected by the post-annealing. The optical bandgap of the film (x = 0.1) after the post-annealing with a Zn cap was 3.41 eV.
Reducing bias and increasing surgical knowledge: multicentre prospective breast cancer studies
Authors: Sund M
Published: February 2021

In the March issue of BJS several hot topics within the breast surgery field are highlighted in beautifully planned and executed prospective multicentre trials. BJS encourages the surgical communities in most fields to move towards prospective collaborative and multicentre studies, thereby increasing both power and generalizability as well as reducing the risk of bias.
Identification of Caenorhabditis elegans Genes Required for Neuronal Differentiation and Migration
Authors: Forrester Wayne C , Perens Elliot , Zallen Jennifer A , Garriga Gian
Published: February 2021

To understand the mechanisms that guide migrating cells, we have been studying the embryonic migrations of the C. elegans canal-associated neurons (CANs). Here, we describe two screens used to identify genes involved in CAN migration. First, we screened for mutants that died as clear larvae (Clr) or had withered tails (Wit), phenotypes displayed by animals lacking normal CAN function. Second, we screened directly for mutants with missing or misplaced CANs. We isolated and characterized 30 mutants that defined 14 genes necessary for CAN migration. We found that one of the genes, ceh-10, specifies CAN fate. ceh-10 had been defined molecularly as encoding a homeodomain protein expressed in the CANs. Mutations that reduce ceh-10 function result in Wit animals with CANs that are partially defective in their migrations. Mutations that eliminate ceh-10 function result in Clr animals with CANs that fail to migrate or express CEH-23, a CAN differentiation marker. Null mutants also fail to express CEH-10, suggesting that CEH-10 regulates its own expression. Finally, we found that ceh-10 is necessary for the differentiation of AIY and RMED, two additional cells that express CEH-10.
An Extensive 3′ Regulatory Region Controls Expression of Bmp5 in Specific Anatomical Structures of the Mouse Embryo
Authors: DiLeone Ralph J , Russell Liane B , Kingsley David M
Published: February 2021

Bone morphogenetic proteins (BMPs) are secreted signaling molecules that control important developmental events in many different organisms. Previous studies have shown that BMPs are expressed at the earliest stages of skeletal development, and are required for formation of specific skeletal features, strongly suggesting that they are endogenous signals used to control formation of skeletal tissue. Despite the importance of BMP signaling in normal development, very little is known about the mechanisms that control the synthesis and distribution of BMP signals in vertebrates. Here, we identify a large array of cis-acting control sequences that lay out expression of the mouse Bmp5 gene in specific skeletal structures and soft tissues. Some of these elements show striking specificity for particular anatomical features within the skeleton, rather than for cartilage and bone in general. These data suggest that the vertebrate skeleton is built from the sum of many independent domains of BMP expression, each of which may be controlled by separate regulatory elements driving expression at specific anatomical locations. Surprisingly, some of the regulatory sequences in the Bmp5 gene map over 270 kb from the Bmp5 promoter, making them among the most distant elements yet identified in studies of eukaryotic gene expression.
Isolation of a Schizosaccharomyces pombe rad21ts Mutant That Is Aberrant in Chromosome Segregation, Microtubule Function, DNA Repair and Sensitive to Hydroxyurea: Possible Involvement of Rad21 in Ubiquitin-Mediated Proteolysis
Authors: Tatebayashi Kazuo , Kato Jun-ichi , Ikeda Hideo
Published: February 2021

The fission yeast DNA repair gene rad21+ is essential for cell growth. To investigate the function essential for cell proliferation, we have isolated a temperature-sensitive mutant of the rad21+ gene. The mutant, rad21-K1, showed abnormal mitosis at the nonpermissive temperature. Some cells contained abnormal nuclear structures, such as condensed chromosomes with short spindles, or chromosomes stretched or unequally separated by elongating spindles. Other cells exhibited the displaced nucleus or a cut-like phenotype. Similar abnormalities were observed when the Rad21 protein was depleted from cells. We therefore concluded that Rad21 is essential for proper segregation of chromosomes. Moreover, the rad21-K1 mutant is sensitive not only to UV and γ-ray irradiation but to thiabendazole and hydroxyurea, indicating that Rad21 plays important roles in microtubule function, DNA repair, and S phase function. The relation to the microtubule function was further confirmed by the fact that rad21+ genetically interacts with tubulin genes, nda2+ and nda3+. Finally, the growth of the rad21-K1 mutant was inhibited at the permissive temperature by introduction of another mutation in the cut9+ gene, coding for a component of the 20S cyclosome/anaphase promoting complex, which is involved in ubiquitin-mediated proteolysis. The results suggest that these diverse functions of Rad21 may be facilitated through ubiquitin-mediated proteolysis.
A Genetic Linkage Map of a Cichlid Fish, the Tilapia (Oreochromis niloticus)
Authors: Kocher Thomas D , Lee Woo-Jai , Sobolewska Halina , Penman David , McAndrew Brendan
Published: February 2021

We have constructed a genetic map for a tilapia, Oreochromis niloticus, using DNA markers. The segregation of 62 microsatellite and 112 anonymous fragment length polymorphisms (AFLPs) was studied in 41 haploid embryos derived from a single female. We have identified linkages among 162 (93.1%) of these markers. 95% of the microsatellites and 92% of the AFLPs were linked in the final map. The map spans 704 Kosambi cM in 30 linkage groups covering the 22 chromosomes of this species. Twenty-four of these linkage groups contain at least one microsatellite polymorphism. From the number of markers 15 or fewer cM apart, we estimate a total map length of ~1000–1200 cM. High levels of interference are observed, consistent with measurements in other fish species. This map is a starting point for the mapping of single loci and quantitative traits in cichlid fishes.
Biased Short Tract Repair of Palindromic Loop Mismatches in Mammalian Cells
Authors: Taghian Danielle G , Hough Heather , Nickoloff Jac A
Published: February 2021

Mismatch repair of palindromic loops in the presence or absence of single-base mismatches was investigated in wild-type and mismatch-binding defective mutant Chinese hamster ovary cells. Recombination intermediates with a maximum heteroduplex DNA (hDNA) region of 697 bp contained a centrally located, phenotypically silent 12-base palindromic loop mismatch, and/or five single-base mismatches. In wild-type cells, both loops and single-base mismatches were efficiently repaired (80–100%). When no other mismatches were present in hDNA, loops were retained with a 1.6–1.9:1 bias. However, this bias was eliminated when single-base mismatches were present, perhaps because single-base mismatches signal nick-directed repair. In the multiple marker crosses, most repair tracts were long and continuous, with preferential loss of markers in cis to proximal nicks, consistent with nicks directing most repair in this situation. However, ~25% of repair tracts were discontinuous as a result of loop-specific repair, or from segregation or short tract repair of single-base mismatches. In mutant cells, single-base mismatches were repaired less frequently, but the loop was still repaired efficiently and with bias toward loop retention, indicating that the defect in these cells does not affect loop-specific repair. Repair tracts in products from mutant cells showed a wide variety of mosaic patterns reflecting short regions of repair and segregation consistent with reduced nick-directed repair. In mutant cells, single-base mismatches were repaired more efficiently in the presence of the loop than in its absence, a likely consequence of corepair initiated at the loop.
Effect of the Pairing Gene Ph1 on Centromere Misdivision in Common Wheat
Authors: Vega Juan M , Feldman Moshe
Published: February 2021

The cytologically diploid-like meiotic behavior of hexaploid wheat (i.e., exclusive bivalent pairing of homologues) is largely controlled by the pairing homoeologous gene Ph1. This gene suppresses pairing between homoeologous (partially homologous) chromosomes of the three closely related genomes that compose the hexaploid wheat complement. It has been previously proposed that Ph1 regulates meiotic pairing by determining the pattern of premeiotic arrangement of homologous and homoeologous chromosomes. We therefore assume that Ph1 action may be targeted at the interaction of centromeres with spindle microtubules—an interaction that is critical for movement of chromosomes to their specific interphase positions. Using monosomic lines of common wheat, we studied the effect of this gene on types and rates of centromere division of univalents at meiosis. In the presence of the normal two doses of Ph1, the frequency of transverse breakage (misdivision) of the centromere of univalent chromosomes was high in both first and second meiotic divisions; whereas with zero dose of the gene, this frequency was drastically reduced. The results suggest that Ph1 is a trans-acting gene affecting centromere-microtubules interaction. The findings are discussed in the context of the effect of Ph1 on interphase chromosome arrangement.
Suppressors of an Arabidopsis thaliana phyB Mutation Identify Genes That Control Light Signaling and Hypocotyl Elongation
Authors: Reed Jason W , Elumalai Rangasamy P , Chory Joanne
Published: February 2021

Ambient light controls the development and physiology of plants. The Arabidopsis thaliana photoreceptor phytochrome B (PHYB) regulates developmental light responses at both seedling and adult stages. To identify genes that mediate control of development by light, we screened for suppressors of the long hypocotyl phenotype caused by a phyB mutation. Genetic analyses show that the shy (short hypocotyl) mutations we have isolated fall in several loci. Phenotypes of the mutants suggest that some of the genes identified have functions in control of light responses. Other loci specifically affect cell elongation or expansion.
Selection with Recurrent Backcrossing to Develop Congenic Lines for Quantitative Trait Loci Analysis
Authors: Hill William G
Published: February 2021

Sewall Wright suggested that genes of large effect on a quantitative trait could be isolated by recurrent backcrossing with selection on the trait. Loci [quantitative trait loci (QTL)] at which the recurrent and nonrecurrent lines have genes of different large effect on the trait would remain segregating, while other loci would become fixed for the gene carried by the recurrent parent. If the recurrent line is inbred and the backcrossing and selection is conducted in a series of replicate lines, in each of which only one backcross parent is selected for each generation, the lines will become congenic to the recurrent parent except for the QTL of large effect and closely linked regions of the genome, and these regions can be identified using a dense set of markers that differ between the parental lines. Such lines would be particularly valuable for subsequent fine-scale mapping and gene cloning; but by chance, even QTL of large effect will be lost from some lines. The probability that QTL of specified effect remain segregating is computed as a function of its effect on the trait, the intensity of selection, and the number of generations of backcrossing. Analytical formulas are given for one or two loci, and simulation is used for more. It is shown that the method could have substantial discriminating ability and thus potential practical value.
Factors Affecting Inverted Repeat Stimulation of Recombination and Deletion in Saccharomyces cerevisiae
Authors: Lobachev Kirill S , Shor Boris M , Tran Hiep T , Taylor Wendy , Keen J Dianne , Resnick Michael A , Gordenin Dmitry A
Published: February 2021

Inverted DNA repeats are an at-risk motif for genetic instability that can induce both deletions and recombination in yeast. We investigated the role of the length of inverted repeats and size of the DNA separating the repeats for deletion and recombination. Stimulation of both deletion and recombination was directly related to the size of inverted repeats and inversely related to the size of intervening spacers. A perfect palindrome, formed by two 1.0-kb URA3-inverted repeats, increased intra- and interchromosomal recombination in the adjacent region 2,400-fold and 17,000-fold, respectively. The presence of a strong origin of replication in the spacer reduced both rates of deletion and recombination. These results support a model in which the stimulation of deletion and recombination by inverted repeats is initiated by a secondary structure formed between single-stranded DNA of inverted repeats during replication.
Antimutator Mutants in Bacteriophage T4 and Escherichia coli
Authors: Schaaper Roel M
Published: February 2021

Antimutators are mutant strains that have reduced mutation rates compared to the corresponding wild-type strain. Their existence, along with mutator mutants that have higher mutation rates compared to the wild-type strain, are powerful evidence that mutation rates are genetically controlled. Compared to mutator mutants, antimutators have a very distinguishing property. Because they prevent normally occurring mutations, they, uniquely, are capable of providing insight into the mechanisms of spontaneous mutations. In this review, antimutator mutants are discussed in bacteriophage T4 and the bacterium Escherichia coli, with regard to their properties, possible mechanisms, and implications for the sources of spontaneous mutations in these two organisms.
Hypermutability in Carcinogenesis
Authors: Strauss Bernard S
Published: February 2021

The presence of numerous chromosomal changes and point mutations in tumors is well established. At least some of these changes play a role in the development of the tumors. It has been suggested that the number of these genetic changes requires that tumorigenesis involves an increase in mutation rate. However, the presence of numerous changes can also be accounted for by efficient selection. What is required to settle the issue is some measure of nonselected mutations in tumors. In order to determine whether the tumor suppressor TP53 (coding for the protein p53) is hypermutable at some stage of carcinogenesis, the frequency of silent and multiple mutations in this gene has been examined. Silent mutations make up ~3% of the total recorded but constitute 9.5% of the mutations found in tumors with multiple mutations. Multiple closely linked mutations are also observed. Such multiple mutations suggest the operation of an error-prone replication process in a subclass of cells. The published data indicate that TP53 is hypermutable at some stage of tumor development. It is not yet clear whether TP53 is unique or whether other genes display a similar pattern of silent and multiple mutations.
Functional Overlap in Mismatch Repair by Human MSH3 and MSH6
Authors: Umar Asad , Risinger John I , Glaab Warren E , Tindall Kenneth R , Barrett J Carl , Kunkel Thomas A
Published: February 2021

Three human genes, hMSH2, hMSH3, and hMSH6, are homologues of the bacterial MutS gene whose products bind DNA mismatches to initiate strand-specific repair of DNA replication errors. Several studies suggest that a complex of hMSH2·hMSH6 (hMutSα) functions primarily in repair of base·base mismatches or single extra bases, whereas a hMSH2·hMSH3 complex (hMutSβ) functions chiefly in repair of heteroduplexes containing two to four extra bases. In the present study, we compare results with a tumor cell line (HHUA) that is mutant in both hMSH3 and hMSH6 to results with derivative clones containing either wild-type hMSH3 or wild-type hMSH6, introduced by microcell-mediated transfer of chromosome 5 or 2, respectively. HHUA cells exhibit marked instability at 12 different microsatellite loci composed of repeat units of 1 to 4 base pairs. Compared to normal cells, HHUA cells have mutation rates at the HPRT locus that are elevated 500-fold for base substitutions and 2400-fold for single-base frameshifts. Extracts of HHUA cells are defective in strand-specific repair of substrates containing base·base mismatches or 1–4 extra bases. Transfer of either chromosome 5 (hMSH3) or 2 (hMSH6) into HHUA cells partially corrects instability at the microsatellite loci and also the substitution and frameshift mutator phenotypes at the HPRT locus. Extracts of these lines can repair some, but not all, heteroduplexes. The combined mutation rate and mismatch repair specificity data suggest that both hMSH3 and hMSH6 can independently participate in repair of replication errors containing base·base mismatches or 1–4 extra bases. Thus, these two gene products share redundant roles in controlling mutation rates in human cells.
Posttranslational Inhibition of Ty1 Retrotransposition by Nucleotide Excision Repair/Transcription Factor TFIIH Subunits Ssl2p and Rad3p
Authors: Lee Bum-Soo , Lichtenstein Conrad P , Faiola Brenda , Rinckel Lori A , Wysock William , Curcio M Joan , Garfinkel David J
Published: February 2021

rtt4-1 (regulator of Ty transposition) is a cellular mutation that permits a high level of spontaneous Ty1 retrotransposition in Saccharomyces cerevisiae. The RTT4 gene is allelic with SSL2 (RAD25), which encodes a DNA helicase present in basal transcription (TFIIH) and nucleotide excision repair (NER) complexes. The ssl2-rtt (rtt4-1) mutation stimulates Ty1 retrotransposition, but does not alter Ty1 target site preferences, or increase cDNA or mitotic recombination. In addition to ssl2-rtt, the ssl2-dead and SSL2-1 mutations stimulate Ty1 transposition without altering the level of Ty1 RNA or proteins. However, the level of Ty1 cDNA markedly increases in the ssl2 mutants. Like SSL2, certain mutations in another NER/TFIIH DNA helicase encoded by RAD3 stimulate Ty1 transposition. Although Ssl2p and Rad3p are required for NER, inhibition of Ty1 transposition is independent of Ssl2p and Rad3p NER functions. Our work suggests that NER/TFIIH subunits antagonize Ty1 transposition posttranslationally by inhibiting reverse transcription or destabilizing Ty1 cDNA.
High Frequency Recombination During the Sexual Cycle of Dictyostelium discoideum
Authors: Francis David
Published: February 2021

Analysis of Dictyostelium development and cell biology has suffered from the lack of an ordinary genetic system whereby genes can be arranged in new combinations. Genetic exchange between two long ignored strains, A2Cycr and WS205 is here reexamined. Alleles which differ in size or restriction sites between these two strains were found for seven genes. Six of these are in two clusters on chromosome 2. Frequencies of recombinant progeny indicate that the genetic map of the two mating strains is colinear with the physical map recently worked out for the standard nonsexual strain, NC4. The rate of recombination is high, about 0.1% per kilobase in three different regions of chromosome 2. This value is comparable to rates found in yeast, and will permit fine dissection of the genome.