scholarly journals A TRANSFORMING MARKER THAT PRODUCES MERODIPLOIDS WITH HIGH EFFICIENCY AND STABLE TRANSFORMANTS WITH LOW EFFICIENCY IN STREPTOCOCCUS

Genetics ◽  
1975 ◽  
Vol 80 (3) ◽  
pp. 421-443
Author(s):  
Arnold W Ravin ◽  
Michael Ma
Keyword(s):  
High Efficiency ◽  
Single Molecules ◽  
Wild Type ◽  
Erythromycin Resistance ◽  
Low Frequencies ◽  
Similar Treatment ◽  
Stable Transformants ◽  
Donor Type ◽  
Low Efficiency ◽  
Original Donor

ABSTRACT A mutation (ery-r8) conferring a high level of resistance to erythromycin in the Challis strain of Streptoccus sanguis can be transferred to wild-type erythromycin-sensitive recipients via single molecules of donor DNA. The transformants thus produced are of two types: (1) cells slightly more resistant to erythromycin than wild-type and capable of segregating (at a frequency of 2 × 10-4/bacterium/generation) either wild-type or highly-resistant cells like the original donor type; (2) cells phenotypically and genotypically identical to the original donor type. The unstable diploids (ery-r8/+) occur with a frequency equivalent to that obtained with high-efficiency (HE) markers, whereas the stable donor-type (ery-r8) transformants occur with about five hundred times lower frequency. Penetration of the wild-type recipient by more than one molecule of DNA bearing the ery-r8 marker increases by as much as seven times the incidence of stable transformants. UV-irradiation of molecules bearing the ery-r8 marker diminishes their ability to cooperate in producing a stable transformant, although the UV sensitivity of stable transformant production by a single DNA molecule is not different from that of diploid production. Hence, stable transformants do not appear to be produced by a process typical of low efficiency (LE) markers, which are generally highly sensitive to ultraviolet irradiation. Moreover, stable ery-r8 transformants are produced with equally low frequencies in strains of S. pneumoniae that discriminate (hex+) and fail to discriminate (hex-) between HE and LE markers. We postulate that all transformations by the ery-r8 marker result in ery-r8/+ diploids, and that segregation results in the infrequent stable transformants of the original donor type. This hypothesis is supported by the observations that rifampin treatment of ery-r8/+ populations increases the frequency of segregation and similar treatment of wild-type recipients undergoing transformation by the ery-r8 marker increases the frequency of stable transformants.—In producing the ery-r8/+ transformant the r8 allele is integrated close to the site of its wild-type homolog, since single molecules of DNA from this transformant can be shown to carry both alleles. Segregation of either the ery-r8 or + allele is not detectably enhanced by acridine orange or thymidine deprivation.—The ery-r8 marker occurs close to a site of mutation (ery-r2) which confers erythromycin resistance upon ribosomes. When the r2 and r8 markers are jointly transferred, ery-r2-r8/+ genomes are produced in which the r2 marker is stably integrated but the r8 marker is unstably adjoined to its wild-type homolog. Thus, the duplicated region can be quite short. When the ery-r8 marker is stably integrated, the region of the marker is refractory to subsequent transformation. Markers with properties like ery-r8 are not particularly rare, being found with a frequency of about 4% among spontaneous mutations to erythromycin resistance.

scholarly journals CHROMOSOMAL BASIS OF THE MEROZYGOSITY IN A PARTIALLY DIPLOID MUTANT OF PNEUMOCOCCUS

Genetics ◽  
1975 ◽  
Vol 80 (4) ◽  
pp. 667-678
Author(s):  
Mary Lee S Ledbetter ◽  
Rollin D Hotchkiss
Keyword(s):  
High Efficiency ◽  
Point Mutations ◽  
Resistant Mutant ◽  
Chromosomal Marker ◽  
Structural Abnormality ◽  
C Cells ◽  
Wild Type ◽  
Chromosomal Locus ◽  
Low Efficiency ◽  
Derivatives Of

ABSTRACT A sulfonamide-resistant mutant of pneumococcus, sulr-c, displays a genetic instability, regularly segregating to wild type. DNA extracts of derivatives of the strain possess transforming activities for both the mutant and wild-type alleles, establishing that the strain is a partial diploid. The linkage of sulr-c to strr-61, a stable chromosomal marker, was established, thus defining a chromosomal locus for sulr-c. DNA isolated from sulr-c cells transforms two mutant recipient strains at the same low efficiency as it does a wild-type recipient, although the mutant property of these strains makes them capable of integrating classical "low-efficiency" donor markers equally as efficiently as "high efficiency" markers. Hence sulr-c must have a different basis for its low efficiency than do classical low efficiency point mutations. We suggest that the DNA in the region of the sulr-c mutation has a structural abnormality which leads both to its frequent segregation during growth and its difficulty in efficiently mediating genetic transformation.

INTEGRATION EFFICIENCY IN DNA-INDUCED TRANSFORMATION OF PNEUMOCOCCUS. II. GENETIC STUDIES OF MUTANT INTEGRATING ALL THE MARKERS WITH A HIGH EFFICIENCY

Genetics ◽  
1973 ◽  
Vol 75 (1) ◽  
pp. 35-48
Author(s):  
Gérard Tiraby ◽  
Michel Armand Sicard
Keyword(s):  
Ultraviolet Light ◽  
Type Strain ◽  
Wild Type Strain ◽  
High Efficiency ◽  
Wild Type ◽  
Genetic Studies ◽  
X Ray ◽  
Reference Marker ◽  
Low Efficiency ◽  
Integration Efficiency

ABSTRACT Transformation of the pneumococcus mutant 401 by DNA's bearing the standard reference marker and several other markers belonging to two unlinked loci has shown that differences in the integration efficiencies of these markers were considerably reduced in this strain compared to the wild-type strain Cl  3. The sensitivities of mutant 401 to ultraviolet light and to X-ray irradiation are the same as those of Cl  3. However, in 401 all the markers tested are more resistant to inactivation as shown by transformation of 401 and Cl  3 by ultraviolet-irradiated DNA. The increase in resistance is greater for low efficiency (LE) markers than for high efficiency (HE) markers.—The decreased discrimination between LE and HE markers in strain 401 is not due to a mechanism related to modification of markers in the transforming DNA by the recipient cells, nor are the proteins inducing competence of the cells responsible for the differences in the integration efficiencies of various markers.—Genetic studies of the fate of recombinants as well as the measure of the amount of DNA taken up have shown that all the markers are integrated in strain 401 by the same recombination process, that specific to high efficiency markers.

scholarly journals A Brief Review on Solvent-Free Synthesis of Zeolites

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 788
Author(s):  
Jinlin Mei ◽  
Aijun Duan ◽  
Xilong Wang
Keyword(s):  
High Efficiency ◽  
Raw Materials ◽  
Solvent Free ◽  
High Yield ◽  
Control Synthesis ◽  
Mechanical Mixing ◽  
Synthesis Mechanism ◽  
Wastewater Pollution ◽  
Low Efficiency ◽  
Solvent Free Synthesis

The traditional hydrothermal method to prepare zeolite will inevitably use a large amount of water as a solvent, which will lead to higher autogenous pressure, low efficiency, and wastewater pollution. The solvent-free method can be used to synthesize various types of zeolites by mechanical mixing, grinding, and heating of solid raw materials, which exhibits the apparent advantages of high yield, low pollution, and high efficiency. This review mainly introduces the development process of solvent-free synthesis, preparation of hierarchical zeolite, morphology control, synthesis mechanism and applications of solvent-free methods. It can be believed that solvent-free methods will become a research focus and have enormous industrial application potential.

scholarly journals Inflight Transmission of COVID-19 Based on Experimental Aerosol Dispersion Data

2021 ◽  
Author(s):  
Zhaozhi Wang ◽  
Edwin R Galea ◽  
Angus Grandison ◽  
John Ewer ◽  
Fuchen Jia
Keyword(s):  
High Efficiency ◽  
Face Mask ◽  
Generation Rate ◽  
Aviation Industry ◽  
Filtration System ◽  
Dispersion Data ◽  
Low Probability ◽  
Meal Service ◽  
Low Efficiency ◽  
Aerosol Dispersion

Abstract Background An issue of concern to the travelling public is the possibility of in-flight transmission of COVID-19 during long- and short-haul flights. The aviation industry maintains that the probability of contracting the illness is small based on reported cases, modelling and data from aerosol dispersion experiments conducted on-board aircraft. Methods Using experimentally derived aerosol dispersion data for a B777–200 aircraft and a modified version of the Wells-Riley equation we estimate inflight infection probability for a range of scenarios involving quanta generation rate and face mask efficiency. Quanta generation rates were selected based on COVID-19 events reported in the literature while mask efficiency was determined from the aerosol dispersion experiments. Results The MID-AFT cabin exhibits the highest infection probability. The calculated maximum individual infection probability (without masks) for a 2-hour flight in this section varies from 4.5% for the ‘Mild Scenario’ to 60.2% for the ‘Severe Scenario’ although the corresponding average infection probability varies from 0.1% to 2.5%. For a 12-hour flight, the corresponding maximum individual infection probability varies from 24.1% to 99.6% and the average infection probability varies from 0.8% to 10.8%. If all passengers wear face masks throughout the 12-hour flight, the average infection probability can be reduced by approximately 73%/32% for high/low efficiency masks. If face masks are worn by all passengers except during a one-hour meal service, the average infection probability is increased by 59%/8% compared to the situation where the mask is not removed. Conclusions This analysis has demonstrated that while there is a significant reduction in aerosol concentration due to the nature of the cabin ventilation and filtration system, this does not necessarily mean that there is a low probability or risk of in-flight infection. However, mask wearing, particularly high-efficiency ones, significantly reduces this risk.

scholarly journals High Efficiency Generalized Parallel Counters for Look-Up Table Based FPGAs

2015 ◽  
Vol 2015 ◽  
pp. 1-16 ◽  
Author(s):  
Burhan Khurshid ◽  
Roohie Naaz Mir
Keyword(s):  
Power Dissipation ◽  
High Speed ◽  
High Efficiency ◽  
Critical Path ◽  
Fir Filters ◽  
Path Delay ◽  
Look Up Table ◽  
Improved Performance ◽  
Ip Cores ◽  
Low Efficiency

Generalized parallel counters (GPCs) are used in constructing high speed compressor trees. Prior work has focused on utilizing the fast carry chain and mapping the logic onto Look-Up Tables (LUTs). This mapping is not optimal in the sense that the LUT fabric is not fully utilized. This results in low efficiency GPCs. In this work, we present a heuristic that efficiently maps the GPC logic onto the LUT fabric. We have used our heuristic on various GPCs and have achieved an improvement in efficiency ranging from 33% to 100% in most of the cases. Experimental results using Xilinx 5th-, 6th-, and 7th-generation FPGAs and Stratix IV and V devices from Altera show a considerable reduction in resources utilization and dynamic power dissipation, for almost the same critical path delay. We have also implemented GPC-based FIR filters on 7th-generation Xilinx FPGAs using our proposed heuristic and compared their performance against conventional implementations. Implementations based on our heuristic show improved performance. Comparisons are also made against filters based on integrated DSP blocks and inherent IP cores from Xilinx. The results show that the proposed heuristic provides performance that is comparable to the structures based on these specialized resources.

Building Self-Service Printing System on College Educational Administration

2014 ◽  
Vol 889-890 ◽  
pp. 1262-1265
Author(s):  
Chun Fang Shi
Keyword(s):  
Educational Administration ◽  
High Efficiency ◽  
Ic Card ◽  
Hardware System ◽  
Teachers And Students ◽  
Human Cost ◽  
Printing System ◽  
Background Database ◽  
Self Service ◽  
Low Efficiency

Printing system of college educational administration has been managed by artificial, which result in low efficiency and high human cost. So we build a system by docking the software and hardware system of background database based on IC card to realize self-service printing for teachers and students of college, which provide a high-efficiency, convenient and humanized service mode, and enhane the economical sense of teachers and students for creating a green campus.

Indications for Dialysis in Acute Kidney Injury

2020 ◽  
Author(s):  
Ankit Patel ◽  
Kenneth B Christopher
Keyword(s):  
Acute Kidney Injury ◽  
Renal Replacement Therapy ◽  
Replacement Therapy ◽  
High Efficiency ◽  
Kidney Injury ◽  
Intermittent Hemodialysis ◽  
Continuous Venovenous Hemofiltration ◽  
Continuous Venovenous Hemodialysis ◽  
Low Efficiency ◽  
The Impact

Renal replacement therapy (RRT) can be used to support patient’s kidney function in cases of acute kidney injury (AKI). However, timing, modality, and dosing of RRT continue to remain in question. Recent studies have begun to provide data to help guide clinicians on when to initiate RRT, what form of RRT to use ranging from continuous venovenous hemofiltration (VVH) to intermittent hemodialysis, and the impact of high versus low-intensity dosing. Additionally, the risks associated with temporary vascular access with regard to thrombosis and infection, the impact of high efficiency and flux versus low efficiency and flux membranes, and options for anticoagulation in RRT for AKI are also discussed. This review contains 75 references.  Key words: acute kidney injury, chronic kidney disease, continuous venovenous hemofiltration, continuous venovenous hemodialysis, renal replacement therapy, venovenous hemofiltration, 

scholarly journals Insights from Past Trends in Exergy Efficiency and Carbon Intensity of Electricity: Portugal, 1900–2014

Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 534
Author(s):  
Laura Felício ◽  
Sofia T. Henriques ◽  
André Serrenho ◽  
Tiago Domingos ◽  
Tânia Sousa
Keyword(s):  
World War I ◽  
High Efficiency ◽  
Electricity Production ◽  
Transport Sector ◽  
Carbon Intensity ◽  
Renewable Electricity ◽  
World War ◽  
Residential Sector ◽  
Electricity Use ◽  
Low Efficiency

We use the societal exergy analysis to identify periods and factors controlling efficiency dilution and carbon deepening of electricity in Portugal from 1900 to 2014. Besides estimating the carbon intensity of electricity production, we propose a new indicator, the carbon intensity of electricity use, which quantifies CO2/kWh of electricity derived useful exergy. Results show final to useful efficiency dilution until World War I (50% to 30%) due to a decrease in share of the high-efficiency transport sector and from mid-1940s to 1960 and mid-1990s onwards (58% to 47% and 47% to 40%) due to an increase in share of the low efficiency commercial and residential sector. Decarbonization from 1900 to mid-1960s, with carbon intensities of electricity production and use dropping respectively from 12.8 to 0.2 and from 33.6 to 0.4 kg CO2/kWh due to an increase in thermoelectricity efficiencies and an increase in share of hydro. Then, a period of carbon deepening until 1990 with carbon intensities tripling due to a shift in shares from hydro to thermoelectricity and more recently a period of decarbonization with carbon intensities decreasing to 0.35 and 0.9 kg CO2/kWh, due to the increase in renewable electricity despite a dilution in final to useful efficiency.

scholarly journals Efficiency and Persistence of Movento® Treatment against Myzus persicae and the Transmission of Aphid-Borne Viruses

Plants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 2747
Author(s):  
Thomas Armand ◽  
Luâna Korn ◽  
Elodie Pichon ◽  
Marlène Souquet ◽  
Mélissandre Barbet ◽  
...  
Keyword(s):  
Sugar Beet ◽  
Myzus Persicae ◽  
High Efficiency ◽  
Plant Protection ◽  
Management Strategies ◽  
Plant Protection Products ◽  
Viral Transmission ◽  
The European Union ◽  
Low Efficiency ◽  
The Impact

Neonicotinoids are widely used to protect fields against aphid-borne viral diseases. The recent ban of these chemical compounds in the European Union has strongly impacted rapeseed and sugar beet growing practices. The poor sustainability of other insecticide families and the low efficiency of prophylactic methods to control aphid populations and pathogen introduction strengthen the need to characterize the efficiency of new plant protection products targeting aphids. In this study, the impact of Movento® (Bayer S.A.S., Leverkusen, Germany), a tetrameric acid derivative of spirotetramat, on Myzus persicae and on viral transmission was analyzed under different growing temperatures. The results show (i) the high efficiency of Movento® to protect rapeseed and sugar beet plants against the establishment of aphid colonies, (ii) the impact of temperature on the persistence of the Movento® aphicid properties and (iii) a decrease of approximately 10% of the viral transmission on treated plants. These observations suggest a beneficial effect of Movento® on the sanitary quality of treated crops by directly reducing primary infections and indirectly altering, through aphid mortality, secondary infections on which the spread of disease within field depends. These data constitute important elements for the future development of management strategies to protect crops against aphid-transmitted viruses.

scholarly journals General-Purpose Forest Plough

2017 ◽  
Vol 7 (3) ◽  
pp. 193-200
Author(s):  
Иван Бартенев ◽  
Ivan Bartenev ◽  
Михаил Лысыч ◽  
Mikhail Lysych ◽  
Михаил Шабанов ◽  
...  
Keyword(s):  
High Efficiency ◽  
General Purpose ◽  
Soil Conditions ◽  
High Survival ◽  
Modular Construction ◽  
Soil Preparation ◽  
Waterlogged Soils ◽  
Low Efficiency ◽  
Single Instrument ◽  
Specific Amount

The basic soil preparation is an important factor in ensuring high survival rate and preservation of cultural plants. Its objective is to loosen the soil to a predetermined depth, it is also important to ensure the containment of weeds growth in areas, adjacent to the row of crop strips. Depending on soil conditions it may be cutting of one or double earthboard furrows (drained soil) and in the formation of microhill (temporarily waterlogged soils). For these purposes, currently, ploughs PKL-70, PRL-70, PL-1, PLM-1.5A, PDV-1.5, PL-2-50, PLD-1.2, etc. are used. Their common drawback is the ability to perform only one operation. A large variety of used tillage equipment and its low efficiency confirms the urgency of developing multi-tools modular construction. This will effectively produce basic preparation of the soil in a variety of conditions with a single instrument. The article provides a description of design and basic layout options of multifunctional plough. By simple changeovers, carried out on site, the plough can be adapted for the main preparation of soil on clearings with drained and temporarily waterlogged soils. It is also possible to change the distance between the bodies of the plow in accordance with the specified rows and rearrange them to work "in" or "out". Process works is modeled in conditions of non-uprooted cutting. The simulation experiment showed high efficiency of the plough, which is ensured by the presence of safety recoverable devices. Replacement in the forestry enterprise of a set of ploughs with one multipurpose plough will reduce total specific amount of metal almost in 4 times.

Sign in / Sign up

Export Citation Format

Share Document