bluuebunny/crossref_metadata_2025 huggingface dataset:
System and method of drip test device for testing waterproof performance of large equipment
Authors: Zhou Yuan , Cong Lin , Peng Lei , Zhou Yongtao , Zhang Yin , Yun Xuefeng
Published: January 2021

At present, the drip test device used in drip test is limited by the difficulty and cost of structural layout, so it is difficult to actively rotate the electrical equipment with large volume and weight, and can not meet the test requirements of various products. In view of the defects of the existing technology, this paper provides a water-proof performance drip test device, system and method. Through the active rotation of the drip pan, the rotation relative to the large-scale test equipment is generated, so as to meet the needs of the equipment waterproof performance test; and the corresponding equipment support is configured to make the equipment form the required angle state during the dripping test, which is convenient for large size Water proof test operation of electrical equipment. At the same time, it makes the test process easy for the staff to operate, has strong economic value and social significance, and can be widely used in testing units.
Study on Restoration Design of River Water Ecosystem in the New Period
Authors: Li Hong , Zhao Qianqian
Published: January 2021

All Focusing on the thinking of water management in the new period, the STS model of river ecosystem restoration design is established, and the spiral development model of water ecosystem restoration is proposed. The role of science, technology and society in the restoration process and the relationship among them are systematically elaborated. The key procedures of each element operation are summarized under the framework of the model.It provides a reference for river ecosystem restoration in the new period.
Analysis of China’s domestic water prediction
Authors: Wei Jiangqiao , Guo Xiaoqian , Yan Qiang , Wang Anjian , Bian Hao
Published: January 2021

With the rapid development of industrialization and urbanization rate, the domestic water consumption in China shows a rapid increasing trend. This paper summarizes the relationship between per capita domestic water consumption, urbanization rate and per capita GDP by studying the domestic water consumption laws of typical countries in the world. The domestic water structure of the United States, France, Germany and Japan were chosen as study case. And we find the similarity of domestic water structure between Japan and China, which means Japan can be used as a sample for analogy prediction. Then, the overall prediction and analogy prediction are used to forecast the domestic water demand in China. The results show that the results of these two methods are consistent. The prediction results can help decision-making departments to make reasonable policies in water resources planning.
Analysis of Oil Displacement Efficiency of Subsequent Water Flooding Reservoir by Polymer Flooding
Authors: Sun Jing
Published: January 2021

After many years of development of basic well pattern and polymer flooding, the block reservoir has high comprehensive water cut, high water flooded degree and high proportion of water absorbing thickness of high permeability reservoir. In this paper, the water flooding characteristics of each sedimentary unit in the subsequent water flooding reservoir of polymer flooding, the existence and quality of oil in pores, the oil displacement efficiency and the factors affecting the oil displacement efficiency are analyzed based on the data of water flooded layer of updated wells and the coring data of new wells in recent years.
Numerical simulation and field test of dust control effect of exhaust ventilation in fully mechanized face
Authors: Ma Wei , Mo Jinming
Published: January 2021

In view of the ventilation status of xiaobaodang coal mine fully mechanized driving face, this paper puts forward the idea of using full extraction ventilation to solve the problem of pollution air leakage in long pressure short suction ventilation, which provides a new idea for dust control of fully mechanized excavation in xiaobaodang coal mine. Solid geometry model of fully mechanized driving face is established by SolidWorks. The influence of different distance between suction outlet and head-on and different air volume on dust migration distribution and dust control effect is analyzed by fluent. The results show that the best dust control effect is obtained when the air volume is set at 300m3 / min and the distance between the suction outlet and the head-on is 5m. The dust concentration is lower than 10mg / m3 in the air duct side, 8m in the central section of the air duct and 16m in the height of the respiratory zone on the pedestrian side. The dust control effect is better at the side far away from the air duct. The measured results are consistent with the numerical simulation results. In addition, the optimized dust control method was verified on site, and the dust reduction efficiency at the driver's place and personnel walking position reached 62.8% and 82.8% respectively.
Research on Vibration Fault Diagnosis Technology of Steam Turbine Unit in Power Plant Based on Wavelet Theory
Authors: Sun Yu , Han Xuhui
Published: January 2021

Aiming at the frequency spectrum characteristics of the vibration of steam turbine generator sets, a fault diagnosis method of steam turbine rotor vibration based on wavelet packet transform is proposed, which can better reflect the spectral components and energy contained in vibration signals than general wavelet transform. Experimental analysis shows that the fault feature extraction method based on wavelet packet analysis and signal energy decomposition can obtain the fault status of steam turbine rotor vibration; according to the frequency spectrum characteristics of different faults, different faults can be identified, so as to perform steam turbine rotor vibration fault diagnosis. This method is more effective than the fault feature extraction method based on Fourier transform and is suitable for mechanical fault diagnosis.
A multi-energy complementary virtual power plant operation optimization model for distributed energy aggregation is considered
Authors: Qu Xiaoyun , Xiong Xiong , Ji Yu , Zhang Ying , Gong Chuanzheng , Liu Hang
Published: January 2021

In this paper, a stochastic scheduling optimization model of virtual power plant (VPP) is established to maximize the net operating income of VPP considering the loss of uncertain risks. Firstly, the model of conventional scheduling optimization of virtual power plant is presented. Then, the risk conditional value (CVaR) theory is introduced to quantify the operational risk level of VPP, and the constraint conditions containing random variables are converted by the confidence method to establish the risk avoidance scheduling optimization model of VPP. Finally, an improved IIEEE30 node system is used as a simulation system to verify the validity and applicability of the proposed model.
Study on SrNb-Oxide Cathode Material for Low-temperature Solid Oxide Fuel Cell
Authors: Zheng Dan , He Qiong , Gao Ji , Wang Baoyuan
Published: January 2021

In this paper, a novel semiconductor-ionic SrNb oxide (SNO)-Ce0.8Sm0.2O2-δ(SDC) composite has been prepared, characterized and developed as a membrane, which is sandwiched between two layers of Ni-foam coated with Ni0.8Co0.15Al0.05LiO2-δ(NCAL) to construct single layer fuel cell (SLFC, the branch of solid oxide fuel cell). Such a device presented an open circuit voltage (OCV) of 1.03V and maximum power density of 630 mW/cm2 at 550 °C when the mass ratio of SNO to SDC is 1:9. The feasible study of solid oxide in fuel cells will provide experimental and theoretical support for the development of SLFC technology.
Optimization of EDM Electrode by Direct Metal Laser Sintering (DMLS) method for SS316L Material
Authors: Shashank S , Pinto Thomas , Ramachandra C G , Raghavendra M J
Published: January 2021

EDM is one of the methods used in processing. It is a process in which the eroded material starts from the piece with the aid of a series of sparks to obtain the desired shape. It is useful for processing hard metals. The work done by several researchers helps in producing EDM electrodes through SLS, as a different method to conventional processing techniques, and to assess the action of electrodes produced with the technique. Due to this reason, experimental research is carried by SLS out on electrodes made from brass, copper alloy and nickel alloy of bronze and nickel, and steel alloy disintegration of a solid substance. EDM recital is evaluated in terms of material deposition (Vw), which represents the volume of extract from the piece per unit of time (cubic meters per second) and correlative magnitude wear (θ), which shows the relationship between the rate of electrode wear and the rate of material withdrawn. A comparative study between the electrodes produced by SLS and the electrodes made in a conventional manner with respect to SS316L material is made.
Fracture Toughness Measurement of Aluminium and Steel Inserted Aluminium Using Numerical Method
Authors: Kumar Mohan , Londhe Neelakantha V
Published: January 2021

The aim of the current work is to test the possibility of improvement of fracture properties of a shaft fabricated by press fitting a rod inside a tube and explore the effect of interface on the crack propagation. Measurement of Mode II fracture toughness is considered for this purpose. In this study numerical method developed by Yong Li and Viola based on Kienzler and Herrmann’s method by conducting a simple shear test on round bar specimen is adopted. Round bar specimens with a circumferential notch are subjected to shear test. Three specimens are prepared using Al6061T6 alloy tube inserted with rod of three different materials A6061T6 alloy, commercial pure Copper, and AISI1045 steel. Also a plain rod of Al6061T6 alloy is tested under shear to compare the results. Shear tests are conducted on Universal Testing Machine and fracture toughness values are calculated using modified Kienzler and Herrmann’s equations. The results indicated an improvement of 18% in the fracture toughness values in the case of A6061T6 alloy rod inserted A6061T6 alloy tube compared to the fracture toughness of plain A6061T6 alloy rod. And when steel rod is inserted inside the A6061T6 alloy tube an improvement of 33.33% in the fracture toughness.
Impact of Alumina Particulates Addition on Hardness and Wear Behaviour of 2014 Al Metal Matrix Composites by Vortex Method
Authors: Bharath V , Auradi V , Nagaral Madeva , Dayanand Samuel , Boppana Satish Babu
Published: January 2021

In this study, 2014 Al matrix alloy reinforced with a 9 wt% of alumina (20 μm) particulates composites by novel two stage melt stirring (stir casting) practice used to synthesize, describe and analyze wear behaviour. Adding up of reinforcement was kept at 0 and 9wt%. For each wt. % preheated (i.e., 250°C) alumina particles were introduced in to the molten 2014Al alloy in steps of two by creating a vortex to overcome the clustering effects. Produced composite was examined by SEM analysis in support of exploring the microstructures and chemical components. Additionally characterization of wear studies of cast 2014Al matrix alloy and 2014Al-Al2O3 particulate composites were analyzed. After the assessment, it had been seen that there is an improvement in the hardness of the composites prepared and this is due to the incorporation of Al2O3 particulates in 2014Al alloy matrix meanwhile. Additionally, the wear rate of all composites prepared diminishes with increase in sliding distance while the wear rate of the composites prepared enhances with increase in load. By using Scanning Electron Microscope (SEM) the diverse wear mechanism for different test states of various compositions were examined.
Investigation on the Microstructure and Mechanical Properties of Aluminum 7075 Reinforced With Different Weight Percentage of Tungsten Carbide and Cobalt Metal Matrix Hybrid Composites
Authors: Guruchannabasavaiah N G , Auradi Virupaxi , Nandeeshaiah B M , Boppana Satish Babu , Nishanth B N
Published: January 2021

In this paper an effort has made to develop and characterize Al7075 alloy reinforced with Tungsten carbide (WC) & Cobalt (Co). For uniform grain size and homogeneity of the reinforcements with matrix, Cermets (WC-Co) of grain size 50 microns were prepared with the help of ball milling operation. An experiment was conducted to evaluate the microstructure; mechanical properties like hardness test & tensile test as per the standards for different weight percentages of Cermets like 3, 6 and 9wt. %. Micrographs were studied to know the micro structure of the composite material and the result showed the, randomly dispersed reinforcement particles & fine interdendritic precipitates were seen. A comparative study was conducted for the microstructure and mechanical properties by using Cermets with varied weight percentages reinforced with Al7075 matrix. Mechanical properties results reveal that there is a considerable improvement in tensile strength and hardness as the percentage of Cermet increased from 3 to 9wt. %.
Structural Analysis of A Two-Wheeler Disc Brake
Authors: Bhat Adarsh , Pal Bhaskar , Dandotiya Devendra
Published: January 2021

Automotive brakes have come a long way, from drum brakes being widely used for a long time until disc brakes came along and began slowly wiping out the usage of drum brakes. This is primarily due to the number of advantages that the disc-pad setup brings - better stopping distance being one of the most important aspects of any braking system. Apart from this, key advantages of disc brakes over drum brakes include better heat dissipation, fade resistance, self-adjusting ability, compact packaging and so on. Although drum brakes too have certain advantages over disc brakes with lesser cost of manufacturing being one of them, the pure superiority of disc brakes outweighs the few benefits of the drum brakes and this has also reflected in the market. However, there is always scope for improvement when it comes to the structural and thermal characteristics of the brake disc. Researches have been carried out to discover better suited materials and brake disc designs to improve the overall structural and thermal characteristics and reduce uneven wear, squealing etc. The aim of this research is to analyze a new design and material combination based on earlier researches to decrease the deformation and provide a base for improving thermal characteristics.
The effect of Zinc Oxide on Operation of Compression Ignition Engine with EGR fueled with Waste Cooking Oil Biodiesel
Authors: Lobo Ashley , Ramesh D K , Chowdhury Dwaipayan Roy
Published: January 2021

Nanoparticles are being used increasingly along with second and third generation biofuels. One major advantage of nanoparticles is its surface to volume ratio and also the number of active surfaces it possess which make it ideal for application as a catalyst in a chemical reaction or in biodiesel’s case an additive. Zinc Oxide (ZnO) has been employed in the current experimentation as an additive because it improves the properties such as the flash and fire point of the fuel in which it is blended in. Also, ZnO disperses well in fluid and provides advanced theoretical density along with not getting clogged in the fuel pump. In the present work Biodiesel derived from Waste cooking oil-Waste cooking oil methyl ester (WCOME) has been used along with ZnO nanoparticle and the amount of ZnO used is 80 ppm. The engine is also fitted with hot Exhaust Gas Recirculation system in order to decrease the Nitrogen Oxides (NOx) emission. Combustion properties such as Heat Release Rate and P-θ diagram have been thoroughly studied. The performance parameters like Brake Specific Fuel Consumption and Break Thermal Efficiency are also calculated and plotted on graphs for evaluation. Exhaust gases from the engine are measured and the results have been plotted on graphs for comparison. The properties of exhaust gases considered are % of Carbon Monoxide, Nitrogen oxides, Unburnt Hydrocarbons & Smoke Opacity. From the results it was revealed that all 3 parameters: Performance, Combustion & Emissions of the engine was improved by using ZnO as additive.
Mathematical Modeling of Boundary Stress State of Orthotropic Material
Authors: Holovata Sofia , Sokolovskyy Yaroslav , Pobereyko Bohdan , Holovatyy Andriy
Published: January 2021

In the paper, the mathematical model for determination of stress and deformation fields inside and at the elastic region boundary of deformation of orthotropic materials under the biaxial loadings is developed. Within the proposed model, a mathematical model for determination of the material transition boundary from elastic into non-elastic deformation region is developed and a system of nonlinear equations for calculation of the values of its parameters is obtained. By using the continuous method of solution continuation with respect to the best parameter and Runge-Kutta method, the demarcation curves of absolutely elastic and non-elastic deformation regions for the pine tree are constructed. The analysis of the obtained curves is carried out and on its base it is shown that the proposed model, in contrast to the known mechanical theories of strength, makes possible to determine and substantiate the ultimate stress states of materials whose asymmetry coefficients of the boundaries of proportionality in some anisotropy directions are greater, and in others less than one.
The Golden Ratio Regularities of Decayed Oscillations
Authors: Kosobutskyy P , Jaworski N , Farmaha I , Marikutsa U , Iwaniec M
Published: January 2021

This paper develops the method for linear oscillator decayed oscillations amplitude division into two unequal parts by so called golden proportion. It is shown that the relaxation time of the area under the envelope of the oscillations amplitudes and the amplitudes themselves coincide, which indicates that the decay time at the golden ratio plays the same role as the relaxation time. This simplifies the algorithm for optimization of oscillatory systems by objective function.
Nocturnal foraging lifts time constraints in winter for migratory geese but hardly speeds up fueling
Authors: Lameris Thomas K , Dokter Adriaan M , van der Jeugd Henk P , Bouten Willem , Koster Jasper , Sand Stefan H H , Westerduin Coen , Nolet Bart A
Published: January 2021

Climate warming advances the optimal timing of breeding for many animals. For migrants to start breeding earlier, a concurrent advancement of migration is required, including premigratory fueling of energy reserves. We investigate whether barnacle geese are time constrained during premigratory fueling and whether there is potential to advance or shorten the fueling period to allow an earlier migratory departure. We equipped barnacle geese with GPS trackers and accelerometers to remotely record birds’ behavior, from which we calculated time budgets. We examined how time spent foraging was affected by the available time (during daylight and moonlit nights) and thermoregulation costs. We used an energetic model to assess onset and rates of fueling and whether geese can further advance fueling by extending foraging time. We show that, during winter, when facing higher thermoregulation costs, geese consistently foraged at night, especially during moonlit nights, in order to balance their energy budgets. In spring, birds made use of the increasing day length and gained body stores by foraging longer during the day, but birds stopped foraging extensively during the night. Our model indicates that, by continuing nighttime foraging throughout spring, geese may have some leeway to advance and increase fueling rate, potentially reaching departure body mass 4 days earlier. In light of rapid climatic changes on the breeding grounds, whether this advancement can be realized and whether it will be sufficient to prevent phenological mismatches remains to be determined.
DeepCNV: a deep learning approach for authenticating copy number variations
Authors: Glessner Joseph T , Hou Xiurui , Zhong Cheng , Zhang Jie , Khan Munir , Brand Fabian , Krawitz Peter , Sleiman Patrick M A , Hakonarson Hakon , Wei Zhi
Published: January 2021

Copy number variations (CNVs) are an important class of variations contributing to the pathogenesis of many disease phenotypes. Detecting CNVs from genomic data remains difficult, and the most currently applied methods suffer from an unacceptably high false positive rate. A common practice is to have human experts manually review original CNV calls for filtering false positives before further downstream analysis or experimental validation. Here, we propose DeepCNV, a deep learning-based tool, intended to replace human experts when validating CNV calls, focusing on the calls made by one of the most accurate CNV callers, PennCNV. The sophistication of the deep neural network algorithm is enriched with over 10 000 expert-scored samples that are split into training and testing sets. Variant confidence, especially for CNVs, is a main roadblock impeding the progress of linking CNVs with the disease. We show that DeepCNV adds to the confidence of the CNV calls with an optimal area under the receiver operating characteristic curve of 0.909, exceeding other machine learning methods. The superiority of DeepCNV was also benchmarked and confirmed using an experimental wet-lab validation dataset. We conclude that the improvement obtained by DeepCNV results in significantly fewer false positive results and failures to replicate the CNV association results.
Accuracy or novelty: what can we gain from target-specific machine-learning-based scoring functions in virtual screening?
Authors: Shen Chao , Weng Gaoqi , Zhang Xujun , Leung Elaine Lai-Han , Yao Xiaojun , Pang Jinping , Chai Xin , Li Dan , Wang Ercheng , Cao Dongsheng , Hou Tingjun
Published: January 2021

Machine-learning (ML)-based scoring functions (MLSFs) have gradually emerged as a promising alternative for protein–ligand binding affinity prediction and structure-based virtual screening. However, clouds of doubts have still been raised against the benefits of this novel type of scoring functions (SFs). In this study, to benchmark the performance of target-specific MLSFs on a relatively unbiased dataset, the MLSFs trained from three representative protein–ligand interaction representations were assessed on the LIT-PCBA dataset, and the classical Glide SP SF and three types of ligand-based quantitative structure-activity relationship (QSAR) models were also utilized for comparison. Two major aspects in virtual screening campaigns, including prediction accuracy and hit novelty, were systematically explored. The calculation results illustrate that the tested target-specific MLSFs yielded generally superior performance over the classical Glide SP SF, but they could hardly outperform the 2D fingerprint-based QSAR models. Although substantial improvements could be achieved by integrating multiple types of protein–ligand interaction features, the MLSFs were still not sufficient to exceed MACCS-based QSAR models. In terms of the correlations between the hit ranks or the structures of the top-ranked hits, the MLSFs developed by different featurization strategies would have the ability to identify quite different hits. Nevertheless, it seems that target-specific MLSFs do not have the intrinsic attributes of a traditional SF and may not be a substitute for classical SFs. In contrast, MLSFs can be regarded as a new derivative of ligand-based QSAR models. It is expected that our study may provide valuable guidance for the assessment and further development of target-specific MLSFs.
Exploring TEAD2 as a drug target for therapeutic intervention of cancer: A multi-computational case study
Authors: Pal Rajesh , Kumar Amit , Misra Gauri
Published: January 2021

Transcriptional enhanced associate domain (TEAD) is a family of transcription factors that plays a significant role during embryonic developmental processes, and its dysregulation is responsible for tumour progression. TEAD is considered as druggable targets in various diseases, namely cancer, cardiovascular diseases and neurodegenerative disorders.

Previous structural studies revealed the importance of the central hydrophobic pocket of TEAD as a potential target for small-molecule inhibitors and demonstrated flufenamic acid (FLU) (a COX-2 enzyme inhibitor) to bind and inhibit TEAD2 functions. However, to date, no drug candidates that bind specifically to TEAD2 with high selectivity and efficacy have been developed or proposed.

Within this framework, we present here a case study where we have identified potential TEAD2 inhibitor candidates by integrating multiple computational approaches. Among the candidates, the top two ranked compounds ZINC95969481 (LG1) which is a fused pyrazole derivative and ZINC05203789 (LG2), a fluorene derivative resulted in much favourable binding energy scores than the reference ligand, FLU. The drug likeliness of the best compounds was also evaluated in silico to ensure the bioavailability of these compounds particularly LG1 as compared to FLU thus providing a strong rationale for their development as leads against TEAD. Molecular dynamics simulations results highlighted the role of key residues contributing to favourable interactions in TEAD2-LG1 complex with much favourable interaction and binding free energy values with respect to the reference compound. Altogether, this study provides a starting platform to be more exploited by future experimental research towards the development of inhibitors against TEAD, a persuasive strategy for therapeutic intervention in cancer treatment.
Nebulosa recovers single-cell gene expression signals by kernel density estimation
Authors: Alquicira-Hernandez Jose , Powell Joseph E
Published: January 2021

Data sparsity in single-cell experiments prevents an accurate assessment of gene expression when visualized in a low-dimensional space. Here, we introduce Nebulosa, an R package that uses weighted kernel density estimation to recover signals lost through drop-out or low expression.

Availability and implementation

Nebulosa can be easily installed from www.github.com/powellgenomicslab/Nebulosa.

Supplementary information

Supplementary data are available at Bioinformatics online.
Chronology of Practice: Chinese Practice in Public International Law in 2019*
Authors: Wu Xiaohui
Published: January 2021

This Survey covers materials reflecting Chinese practice in 2019 relating to: treaties, agreements and other documents signed or ratified by the People’s Republic of China; national legislation; statements made by Chinese representatives at the meetings of the UN and other international organizations, international conferences, and those made by the Foreign Ministry spokespersons, with respect to various branches of international law; and judicial decisions, in particular on the applicability and application of international conventions, by Chinese courts.
Phage Origin of Mitochondrion-Localized Family A DNA Polymerases in Kinetoplastids and Diplonemids
Authors: Harada Ryo , Inagaki Yuji
Published: January 2021

Mitochondria retain their own genomes as other bacterial endosymbiont-derived organelles. Nevertheless, no protein for DNA replication and repair is encoded in any mitochondrial genomes (mtDNAs) assessed to date, suggesting that the nucleus primarily governs the maintenance of mtDNA. As the proteins of diverse evolutionary origins occupy a large proportion of the current mitochondrial proteomes, we anticipate finding the same evolutionary trend in the nucleus-encoded machinery for mtDNA maintenance. Indeed, none of the DNA polymerases (DNAPs) in the mitochondrial endosymbiont, a putative α-proteobacterium, seemingly had been inherited by their descendants (mitochondria), as none of the known types of mitochondrion-localized DNAP showed a specific affinity to the α-proteobacterial DNAPs. Nevertheless, we currently have no concrete idea of how and when the known types of mitochondrion-localized DNAPs emerged. We here explored the origins of mitochondrion-localized DNAPs after the improvement of the samplings of DNAPs from bacteria and phages/viruses. Past studies have revealed that a set of mitochondrion-localized DNAPs in kinetoplastids and diplonemids, namely PolIB, PolIC, PolID, PolI-Perk1/2, and PolI-dipl (henceforth designated collectively as “PolIBCD+”) have emerged from a single DNAP. In this study, we recovered an intimate connection between PolIBCD+ and the DNAPs found in a particular group of phages. Thus, the common ancestor of kinetoplastids and diplonemids most likely converted a laterally acquired phage DNAP into a mitochondrion-localized DNAP that was ancestral to PolIBCD+. The phage origin of PolIBCD+ hints at a potentially large contribution of proteins acquired via nonvertical processes to the machinery for mtDNA maintenance in kinetoplastids and diplonemids.
The genetic dependence of recombination in recD mutants of Escherichia coli.
Authors: Lovett S T , Luisi-DeLuca C , Kolodner R D
Published: January 2021

RecBCD enzyme has multiple activities including helicase, exonuclease and endonuclease activities. Mutations in the genes recB or recC, encoding two subunits of the enzyme, reduce the frequency of many types of recombinational events. Mutations in recD, encoding the third subunit, do not reduce recombination even though most of the activities of the RecBCD enzyme are severely reduced. In this study, the genetic dependence of different types of recombination in recD mutants has been investigated. The effects of mutations in genes in the RecBCD pathway (recA and recC) as well as the genes specific for the RecF pathway (recF, recJ, recN, recO, recQ, ruv and lexA) were tested on conjugational, transductional and plasmid recombination, and on UV survival. recD mutants were hyper-recombinogenic for all the monitored recombination events, especially those involving plasmids, and all recombination events in recD strains required recA and recC. In addition, unlike recD+ strains, chromosomal recombination events and the repair of UV damage to DNA in recD strains were dependent on one RecF pathway gene, recJ. Only a subset of the tested recombination events were affected by ruv, recN, recQ, recO and lexA mutations.
Chromosomal organization of rRNA operons in Bacillus subtilis.
Authors: Jarvis E D , Widom R L , LaFauci G , Setoguchi Y , Richter I R , Rudner R
Published: January 2021

Integrative mapping with vectors containing ribosomal DNA sequences were used to complete the mapping of the 10 rRNA gene sets in the endospore forming bacterium Bacillus subtilis. Southern hybridizations allowed the assignment of nine operons to distinct BclI restriction fragments and their genetic locus identified by transductional crosses. Nine of the ten rRNA gene sets are located between 0 and 70 degrees on the genomic map. In the region surrounding cysA14, two sets of closely spaced tandem clusters are present. The first (rrnJ and rrnW) is located between purA16 and cysA14 closely linked to the latter; the second (rrnI, rrnH and rrnG) previously mapped within this area is located between attSPO2 and glpT6. The operons at or near the origin of replication (rrnO,rrnA and rrnJ,rrnW) represent "hot spots" of plasmid insertion.
The coalescent process in models with selection and recombination.
Authors: Hudson R R , Kaplan N L
Published: January 2021

The statistical properties of the process describing the genealogical history of a random sample of genes at a selectively neutral locus which is linked to a locus at which natural selection operates are investigated. It is found that the equations describing this process are simple modifications of the equations describing the process assuming that the two loci are completely linked. Thus, the statistical properties of the genealogical process for a random sample at a neutral locus linked to a locus with selection follow from the results obtained for the selected locus. Sequence data from the alcohol dehydrogenase (Adh) region of Drosophila melanogaster are examined and compared to predictions based on the theory. It is found that the spatial distribution of nucleotide differences between Fast and Slow alleles of Adh is very similar to the spatial distribution predicted if balancing selection operates to maintain the allozyme variation at the Adh locus. The spatial distribution of nucleotide differences between different Slow alleles of Adh do not match the predictions of this simple model very well.
Genomic Instability in Wheat Induced by Chromosome 6b(s) of Triticum Speltoides.
Authors: Kota R S , Dvorak J
Published: January 2021

A massive restructuring of chromosomes was observed during the production of a substitution of chromosome 6B(s) from Triticum speltoides (Tausch) Gren. ex Richter for chromosome 6B of Chinese Spring wheat (Triticum aestivum L.). Deletions, translocations, ring chromosomes, dicentric chromosomes and a paracentric inversion were observed. Chromosome rearrangements occurred in both euchromatic and heterochromatic regions. Chromosome rearrangements were not observed either in the amphiploid between Chinese Spring and T. speltoides or in Chinese Spring. No chromosome rearrangements were observed in the backcross derivatives; however, after self-pollination of a monosomic substitution (2n = 41) of chromosome 6B(s) for wheat chromosome 6B, 49 of the 138 plants carried chromosome aberrations. Chromosome rearrangements were observed in both wheat and T. speltoides chromosomes. The frequency of chromosome rearrangements was high among the B-genome chromosomes, moderate among the A-genome chromosomes, and low among the D-genome chromosomes. In the B genome, the rearrangements were nonrandom, occurring most frequently in chromosomes 1B and 5B. Chromosome rearrangements were also frequent for the 6B(s) chromosome of T. speltoides. An intriguing aspect of these observations is that they indicate that wheat genomes can be subject to uneven rates of structural chromosome differentiation in spite of being in the same nucleus.
Adaptive evolution that requires multiple spontaneous mutations. I. Mutations involving an insertion sequence.
Authors: Hall B G
Published: January 2021

Escherichia coli K12 strain chi 342LD requires two mutations in the bgl (beta-glucosidase) operon, bglR0----bglR+ and excision of IS103 from within bglF, in order to utilize salicin. In growing cells the two mutations occur at rates of 4 x 10(-8) per cell division and less than 2 x 10(-12) per cell division, respectively. In 2-3-week-old colonies on MacConkey salicin plates the double mutants occur at frequencies of 10(-8) per cell, yet the rate of an unselected mutation, resistance to valine, is unaffected. The two mutations occur sequentially. Colonies that are 8-12 days old contain from 1% to about 10% IS103 excision mutants, from which the Sal+ secondary bglR0----bglR+ mutants arise. It is shown that the excision mutants are not advantageous within colonies; thus, they must result from a burst of independent excisions late in the life of the colony. Excision of IS103 occurs only on medium containing salicin, despite the fact that the excision itself confers no detectable selective advantage and serves only to create the potential for a secondary selectively advantageous mutation.
Molecular characterization of the mitochondrial DNA of a new stopper mutant ER-3 of Neurospora crassa.
Authors: Almasan A , Mishra N C
Published: January 2021

An ethidium bromide-induced stopper mutant of Neurospora crassa is characterized at the molecular level. The mutant has two populations of mitochondrial DNA: a defective predominant mutant molecule and a basal level of the wild-type molecule. The aberrant DNA resulted after a 25-kbp deletion from the wild-type mitochondrial chromosome, which included major genes such as cytb, co1 and oli2. The deletion endpoints are located in the second intron of the ND5 gene, and in a sequence 250 nucleotides upstream of the co2 gene. The recombination has taken place between two nine nucleotide repeats CCCCGCCCC, one of which is close to a PstI palindrome at its 5' end. Thus the mutant ER-3 differs from all the other stopper mutants described previously in the extent and location of the deletions in the mtDNA.
The effects of translocations on recombination frequency in Caenorhabditis elegans.
Authors: McKim K S , Howell A M , Rose A M
Published: January 2021

In the nematode Caenorhabditis elegans, recombination suppression in translocation heterozygotes is severe and extensive. We have examined the meiotic properties of two translocations involving chromosome I, szT1(I;X) and hT1(I;V). No recombination was observed in either of these translocation heterozygotes along the left (let-362-unc-13) 17 map units of chromosome I. Using half-translocations as free duplications, we mapped the breakpoints of szT1 and hT1. The boundaries of crossover suppression coincided with the physical breakpoints. We propose that DNA sequences at the right end of chromosome I facilitate pairing and recombination. We use the data from translocations of other chromosomes to map the location of pairing sites on four other chromosomes. hT1 and szT1 differed markedly in their effect on recombination adjacent to the crossover suppressed region. hT1 had no effect on recombination in the adjacent interval. In contrast, the 0.8 map unit interval immediately adjacent to the szT1(I;X) breakpoint on chromosome I increased to 2.5 map units in translocation heterozygotes. This increase occurs in a chromosomal interval which can be expanded by treatment with radiation. These results are consistent with the suggestion that the szT1(I) breakpoint is in a region of DNA in which meiotic recombination is suppressed relative to the genomic average. We propose that DNA sequences disrupted by the szT1 translocation are responsible for determining the frequency of meiotic recombination in the vicinity of the breakpoint.
MATING TYPE AND SPORULATION IN YEAST I. MUTATIONS WHICH ALTER MATING-TYPE CONTROL OVER SPORULATION
Authors: Hopper Anita K , Hall Benjamin D
Published: January 2021

Fifty-two inositol-requiring mutants of Saccharomyces cerevisiae were isolated following mutagenesis with ethyl methanesulfonate. Complementation and tetrad analysis revealed ten major complementation classes, representing ten independently segregating loci (designated ino1 through ino10) which recombined freely with their respective centromeres. Members of any given complementation class segregated as alleles of a single locus. Thirteen complementation subclasses were identified among thirty-six mutants which behaved as alleles of the ino1 locus. The complementation map for these mutants was circular.—Dramatic cell viability losses indicative of unbalanced growth were observed in liquid cultures of representative mutants under conditions of inositol starvation. Investigation of the timing, kinetics, and extent of cell death revealed that losses in cell viability in the range of 2-4 log orders could be prevented by the addition of inositol to the medium or by disruption of protein synthesis with cycloheximide. Mutants defective in nine of the ten loci identified in this study displayed these unusual characteristics. The results suggest an important physiological role for inositol that may be related to its cellular localization and function in membrane phospholipids. The possibility is discussed that inositol deficiency initiates the process of unbalanced growth leading to cell death through the loss of normal assembly, function, or integrity of biomembranes.—Part of this work has been reported in preliminary form (Culbertson and Henry 1974).
MATING TYPE AND SPORULATION IN YEAST. II. MEIOSIS, RECOMBINATION, AND RADIATION SENSITIVITY IN AN αα DIPLOID WITH ALTERED SPORULATION CONTROL
Authors: Hopper Anita K , Kirsch J , Hall Benjamin D
Published: January 2021

In wild-type S. cerevisiae, diploid cells must be heterozygous at the mating-type locus in order to sporulate. In the preceding paper, we described a number of mutants (CSP mutants), isolated from nonsporulating aa and αα parent strains, in which sporulation appeared to be uncoupled from control by mating type. The characterization of one of these mutants (CSP1) is now extended to other processes controlled by mating type. This mutant is indistinguishable from αα cells and unlike aα cells for mating factor production and response, zygote formation, intragenic mitotic recombination, and for X-ray sensitivity. The mutant apparently undergoes a full round of DNA synthesis in sporulation medium, but with delayed kinetics. Only 20% of the cells complete sporulation. Among spores in completed asci, the frequency of both intra- and intergenic recombination is the same as it is for spores produced by aα cells. However, experiments in which cells were shifted from sporulation medium back to minimal growth medium gave a frequency of meiotic recombination between ade2 or leu2 heteroalleles only 25% to 29% as high for CSP1 αα diploid or CSP1  aa disomic cells as for aα diploid or disomic cells. Because the latter result, indicating recombination defectiveness, measured recombinant production in the entire cell population, whereas the result indicating normal recombination sampled only completed spores, we infer that all meiotic recombination events occurring in the population of CSP1 αα cells are concentrated in those few cells which complete sporulation. This high degree of correlation between meiotic recombination and the completion of meiosis and sporulation suggests that recombination may be required for proper meiotic chromosome segregation in yeast just as it appears to be in maize and in Drosophila
RECOMBINANT CLONE HETEROGENEITY IN ESCHERICHIA COLI CONJUNCTION: EFFECT OF PH AND PARTIALLY REPLICATED RECIPIENT DEOXYRIBONUCLEIC ACID
Authors: Ou Jonathan T
Published: January 2021

At pH 6.8, a substantial fraction of recombinant colonies obtained from conjugation with an HfrH donor contained multiple recombinant classes in a single colony (polygenotypic colony). In contrast, when the conjugation was performed at pH 7.6, the number of polygenotypic colonies was drastically reduced, and the recombinant colonies were predominantly monogenotypic or digenotypic. Genetic analysis revealed that the digenotypic recombinants differ in those donor markers near the origin of DNA replication but share those donor markers near the terminus. This integration pattern suggests that the formation of digenotypic recombinants involves recombination of a single copy of the exogenome with a partially replicated recipient DNA molecule. This suggestion was supported by examination of the genotype of recombinant colonies recovered from crosses with an HfrKL96 donor which was derived from HfrH but transfers its chromosome in the reverse direction.
INTRASPECIFIC VARIATION OF RIBOSOMAL GENE REDUNDANCY IN ZEA MAYS
Authors: Ramirez Samuel A , Sinclair John H
Published: January 2021

Ribosomal genes in eukaryotes are highly redundant. Considerable variation in the level of redundancy among species, especially in higher plants, has been reported; but except for deletion and duplication mutants, it is generally accepted that intraspecific variability in redundancy level is small. We have examined the level of redundancy in several lines of maize by DNA-rRNA saturation hybridization. The amount of nuclear DNA which hybridizes with rRNA in the ten lines examined varied from 0.24% to 0.50%. The number of rRNA genes per diploid genome thus ranges from 1.12 × 104 to 2.32 × 104. Results also indicate that the level of redundancy is genetically transmitted.
A SURVEY OF ISOZYME POLYMORPHISM IN A DROSOPHILA MELANOGASTER NATURAL POPULATION
Authors: Band H T
Published: January 2021

A survey of biochemical polymorphism among glucose- and non-glucose-metabolizing enzymes was carried out on the June 1973 collection from the South Amherst, Mass. Drosophila melanogaster natural population. Polymorphic levels are among the highest recorded for this species; polymorphism among glucose-metabolizing enzymes did not differ significantly from that among non-glucose-metabolizing enzymes. Two loci, G6Pd on the × and Est-6 on the 3rd chromosome, displayed significant excesses of heterozygotes. Adh on the 2nd and Idh, Odh and Ao on the 3rd chromosome showed significant heterozygote deficiencies. Idh is ten map units to the left of Est-6, Odh twelve map units to the right and Ao is seven units beyond Odh. Temperatures in the two-week June period prior to collection were exceedingly variable. Daily high/low ranged between 76°/40° and 97°/65°F. These results support the findings of Frydenberg and Simonsen (1973) that in some populations glucose-metabolizing enzymes tend to be as polymorphic as non-glucose-metabolizing ones. They also add to the evidence obtained from other plant and animal populations that increased biochemical polymorphism is associated with more variable and/or colder climates. The increase may in part be due to increased polymorphism among glucose-metabolizing enzymes. Comparisons utilizing published data on other D. melanogaster populations and on D. robusta indicate a clinal increase in heterozygosity among glucose-metabolizing enzymes as one moves northward.
DIRECTIONAL versus STABILIZING SELECTION FOR DEVELOPMENTAL TIME IN NATURAL AND LABORATORY POPULATIONS OF FLOUR BEETLES
Authors: Dawson Peter S
Published: January 2021

Artificial selection for fast development is successful in long-established laboratory populations of Tribolium, but not in strains recently derived from natural populations. It is shown that selection against fast development in dense, synchronized cultures operates through cannibalism of early pupae by larvae. Since standard husbandry procedures for laboratory strains involve the periodic creation of dense, synchronized cultures, it is suggested that these populations are subjected to stabilizing selection for intermediate developmental time. Natural populations, on the other hand, are probably subjected to directional selection for rapid development.
Negative regulation of FOXP3 expression by c-Rel O-GlcNAcylation
Authors: de Jesus Tristan J , Tomalka Jeffrey A , Centore Joshua T , Staback Rodriguez Franklin D , Agarwal Ruchira A , Liu Angela R , Kern Timothy S , Ramakrishnan Parameswaran
Published: January 2021

O-GlcNAcylation is a reversible post-translational protein modification that regulates fundamental cellular processes including immune responses and autoimmunity. Previously, we showed that hyperglycemia increases O-GlcNAcylation of the transcription factor, nuclear factor kappaB c-Rel at serine residue 350 and enhances the transcription of the c-Rel-dependent proautoimmune cytokines interleukin-2, interferon gamma and granulocyte macrophage colony stimulating factor in T cells. c-Rel also plays a critical role in the transcriptional regulation of forkhead box P3 (FOXP3)—the master transcription factor that governs development and function of Treg cells. Here we show that the regulatory effect of c-Rel O-GlcNAcylation is gene-dependent, and in contrast to its role in enhancing the expression of proautoimmune cytokines, it suppresses the expression of FOXP3. Hyperglycemia-induced O-GlcNAcylation-dependent suppression of FOXP3 expression was found in vivo in two mouse models of autoimmune diabetes; streptozotocin-induced diabetes and spontaneous diabetes in nonobese diabetic mice. Mechanistically, we show that both hyperglycemia-induced and chemically enhanced cellular O-GlcNAcylation decreases c-Rel binding at the FOXP3 promoter and negatively regulates FOXP3 expression. Mutation of the O-GlcNAcylation site in c-Rel, (serine 350 to alanine), augments T cell receptor-induced FOXP3 expression and resists the O-GlcNAcylation-dependent repression of FOXP3 expression. This study reveals c-Rel S350 O-GlcNAcylation as a novel molecular mechanism inversely regulating immunosuppressive FOXP3 expression and proautoimmune gene expression in autoimmune diabetes with potential therapeutic implications.