An Escherichia coli K12 chromosomal EcoRI-BamHI fragment containing a mutant hsdS locus was cloned into plasmid pBR322. The mcrB gene, closely linked to hsdS, was used for selection of clones with the inserted fragment using T4 alpha gt57 beta gt14 and lambda vir. PvuII phages; the phage DNAs contain methylated cytosines and hence can be used to demonstrate McrB restriction. For the efficient expression of the hsdS gene, a BglII fragment of phage lambda carrying the pR promoter was inserted into the BamHI site of the hybrid plasmid. Under these conditions a trans-dominant effect of the hsdXts+d mutation on restriction and modification was detected. Inactivation of the hsdS gene by the insertion of the lambda phage BglII fragment into the BglII site within this gene resulted in the disappearance of the trans-dominant effect. When the cloned BamHI-EcoRI fragment was shortened by HpaI and EcoRI restriction enzymes, the trans-dominant effect was fully expressed. The results indicate that the Xts+d mutation is located in the hsdS gene. The effect of gene dosage of the HsdS subunit on the expression of Xts+d mutation was studied. The results of complementation experiments, using F'-merodiploids or plasmid pBR322 with an inserted Xts+d mutation, support the idea that the HsdSts+d product competes with the wild-type HsdS product, and has a quantitatively different effect on restriction and modification.

• MeSH
• bakteriální geny * MeSH
• DNA restrikčně-modifikační enzymy genetika   MeSH
• dominantní geny MeSH
• Escherichia coli genetika   MeSH
• fenotyp MeSH
• klonování DNA MeSH
• mutace MeSH
• plazmidy MeSH
• restrikční mapování MeSH
• teplota MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• DNA restrikčně-modifikační enzymy MeSH

The majority of thermal modification processes are at temperatures greater than 180 °C, resulting in a product with some properties enhanced and some diminished (e.g., mechanical properties). However, the durability of thermally modified wood to termite attack is recognised as low. Recent attempts at combining thermal modification with chemical modification, either prior to or directly after the thermal process, are promising. Buffers, although not influencing the reaction systems, may interact on exposure to certain conditions, potentially acting as promoters of biological changes. In this study, two zwitterionic buffers, bicine and tricine, chosen for their potential to form Maillard-type products with fragmented hemicelluloses/volatiles, were assessed with and without thermal modification for two wood species (spruce and beech), with subsequent evaluation of their effect against subterranean termites (Reticulitermes grassei Clément) and their symbiotic protists. The effect of the wood treatments on termites and their symbionts was visible after four weeks, especially for spruce treated with tricine and bicine and heat treatment (bicine HT), and for beech treated with bicine and bicine and heat treatment (bicine HT). The chemical behaviour of these substances should be further investigated when in contact with wood and also after heat treatment. This is the first study evaluating the effect of potential Maillard reactions with zwitterionic buffers on subterranean termite symbiotic fauna.

• Klíčová slova
• Reticulitermes grassei, bicine, symbionts, termite gut, thermal modification, tricine, wood,
• Publikační typ
• časopisecké články MeSH

A relevant issue with charred exteriors is the inconsistency of the result, which makes service life predictions complicated. Contact charring enables the creation of a very evenly modified surface with accurate control of temperature and modification time, but the weathering properties are questionable. This paper evaluated the effect of the modification time relative to char layer and transition zone thickness, wood species and material density in an artificial weathering test. The results revealed higher color stability in connection to longer modification time, but also an increase in the cracked surface area. Cracking was heavily dependent on the modification regime and increased with increasing char and transition zone thicknesses. Dense spruce had the highest color stability with the most severe modification regime, but char layer thickness varied more than on other wood types. Furthermore, species-dependent cracking patterns affected the final result as the small-scale flaking experienced by birch increased the washing off of char. It is likely an even higher modification temperature with a shorter modification time is needed to produce sufficient weathering resistance suitable for exterior uses.

• Klíčová slova
• artificial weathering, carbonization, contact charring, surface modification, wood, wood modification,
• Publikační typ
• časopisecké články MeSH

BACKGROUND: Identifying how greenspace impacts the temperature-mortality relationship in urban environments is crucial, especially given climate change and rapid urbanization. However, the effect modification of greenspace on heat-related mortality has been typically focused on a localized area or single country. This study examined the heat-mortality relationship among different greenspace levels in a global setting. METHODS: We collected daily ambient temperature and mortality data for 452 locations in 24 countries and used Enhanced Vegetation Index (EVI) as the greenspace measurement. We used distributed lag non-linear model to estimate the heat-mortality relationship in each city and the estimates were pooled adjusting for city-specific average temperature, city-specific temperature range, city-specific population density, and gross domestic product (GDP). The effect modification of greenspace was evaluated by comparing the heat-related mortality risk for different greenspace groups (low, medium, and high), which were divided into terciles among 452 locations. FINDINGS: Cities with high greenspace value had the lowest heat-mortality relative risk of 1·19 (95% CI: 1·13, 1·25), while the heat-related relative risk was 1·46 (95% CI: 1·31, 1·62) for cities with low greenspace when comparing the 99th temperature and the minimum mortality temperature. A 20% increase of greenspace is associated with a 9·02% (95% CI: 8·88, 9·16) decrease in the heat-related attributable fraction, and if this association is causal (which is not within the scope of this study to assess), such a reduction could save approximately 933 excess deaths per year in 24 countries. INTERPRETATION: Our findings can inform communities on the potential health benefits of greenspaces in the urban environment and mitigation measures regarding the impacts of climate change. FUNDING: This publication was developed under Assistance Agreement No. RD83587101 awarded by the U.S. Environmental Protection Agency to Yale University. It has not been formally reviewed by EPA. The views expressed in this document are solely those of the authors and do not necessarily reflect those of the Agency. EPA does not endorse any products or commercial services mentioned in this publication. Research reported in this publication was also supported by the National Institute on Minority Health and Health Disparities of the National Institutes of Health under Award Number R01MD012769. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. Also, this work has been supported by the National Research Foundation of Korea (2021R1A6A3A03038675), Medical Research Council-UK (MR/V034162/1 and MR/R013349/1), Natural Environment Research Council UK (Grant ID: NE/R009384/1), Academy of Finland (Grant ID: 310372), European Union's Horizon 2020 Project Exhaustion (Grant ID: 820655 and 874990), Czech Science Foundation (22-24920S), Emory University's NIEHS-funded HERCULES Center (Grant ID: P30ES019776), and Grant CEX2018-000794-S funded by MCIN/AEI/ 10.13039/501100011033 The funders had no role in the design, data collection, analysis, interpretation of results, manuscript writing, or decision to publication.

• Klíčová slova
• Effect modification, Greenspace, Heat, Mortality,
• MeSH
• klimatické změny * MeSH
• lidé MeSH
• mortalita MeSH
• velkoměsta MeSH
• vysoká teplota * MeSH
• životní prostředí MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Finsko MeSH
• velkoměsta MeSH

The research results presented in this article were obtained by joint scientific research on creatingcement materials with reduced impedance. It is known that functional additives added to impart electrically conductive properties have a negative impact on physical and mechanical characteristics of the material. This study suggests using the multiwall carbon nanotubes in the amount of 7% from binder mass as a functional additive. The results obtained prove that the addition of this amount of the modifier does not lead to a significant decrease of strength characteristics. Calcium nitrate in the amount of 1-7% was added in order to level the strength loss and to ensure the effective stable electrical conductivity. The multifunctionality of using this salt has been proven, which is manifested in the anti-frost and anticorrosive effects as well in enhancement of electrical conductivity. The optimal composition of the additive with 7% of carbon nanotubes and 3% of calcium nitrate ensures a reduced electrical impedance of cement matrix. The electrical conductivity was 2440 Ohm, while the decrease of strength properties was within 10% in comparison tothe control sample. The nature of changes in the microstructure were studied to determine the influence of complex modifications that showed significant changes in the morphology of the hydration products. The optimum electrical characteristics of cementitious materials are provided due to the uniform distribution of carbon nanotubes and the formation of a network of interconnected micropores filled with the solution of calcium nitrate that provides additional and stable electrical conductivity over time.

• Klíčová slova
• cement binders, complex modification, impedance, morphology, multiwall nanotubes, structure,
• Publikační typ
• časopisecké články MeSH

BACKGROUND: Evidence on the potential interactive effects of heat and ambient air pollution on cause-specific mortality is inconclusive and limited to selected locations. OBJECTIVES: We investigated the effects of heat on cardiovascular and respiratory mortality and its modification by air pollution during summer months (six consecutive hottest months) in 482 locations across 24 countries. METHODS: Location-specific daily death counts and exposure data (e.g., particulate matter with diameters ≤ 2.5 µm [PM2.5]) were obtained from 2000 to 2018. We used location-specific confounder-adjusted Quasi-Poisson regression with a tensor product between air temperature and the air pollutant. We extracted heat effects at low, medium, and high levels of pollutants, defined as the 5th, 50th, and 95th percentile of the location-specific pollutant concentrations. Country-specific and overall estimates were derived using a random-effects multilevel meta-analytical model. RESULTS: Heat was associated with increased cardiorespiratory mortality. Moreover, the heat effects were modified by elevated levels of all air pollutants in most locations, with stronger effects for respiratory than cardiovascular mortality. For example, the percent increase in respiratory mortality per increase in the 2-day average summer temperature from the 75th to the 99th percentile was 7.7% (95% Confidence Interval [CI] 7.6-7.7), 11.3% (95%CI 11.2-11.3), and 14.3% (95% CI 14.1-14.5) at low, medium, and high levels of PM2.5, respectively. Similarly, cardiovascular mortality increased by 1.6 (95%CI 1.5-1.6), 5.1 (95%CI 5.1-5.2), and 8.7 (95%CI 8.7-8.8) at low, medium, and high levels of O3, respectively. DISCUSSION: We observed considerable modification of the heat effects on cardiovascular and respiratory mortality by elevated levels of air pollutants. Therefore, mitigation measures following the new WHO Air Quality Guidelines are crucial to enhance better health and promote sustainable development.

• Klíčová slova
• Air pollution, Air temperature, Cardiovascular mortality, Effect modification, Heat, Respiratory mortality,
• MeSH
• kardiovaskulární nemoci * mortalita   MeSH
• látky znečišťující vzduch toxicita   analýza   MeSH
• látky znečišťující životní prostředí MeSH
• lidé MeSH
• mortalita MeSH
• nemoci dýchací soustavy epidemiologie   MeSH
• pevné částice škodlivé účinky   analýza   MeSH
• velkoměsta epidemiologie   MeSH
• vysoká teplota MeSH
• vystavení vlivu životního prostředí * škodlivé účinky   analýza   MeSH
• znečištění ovzduší * analýza   statistika a číselné údaje   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• velkoměsta epidemiologie   MeSH
• Názvy látek
• látky znečišťující vzduch MeSH
• látky znečišťující životní prostředí MeSH
• pevné částice MeSH

Recently, polymers have become the fastest growing and most widely used material in a huge number of applications in almost all areas of industry. In addition to standard polymer composites with synthetic matrices, biopolymer composites based on PLA and PHB matrices filled with fibers of plant origin are now increasingly being used in selected advanced industrial applications. The article deals with the evaluation of the influence and effect of the type of surface modification of cellulose fibers using physical methods (low-temperature plasma and ozone application) and chemical methods (acetylation) on the final properties of biopolymer composites. In addition to the surface modification of natural fibers, an additional modification of biocomposite structural systems by radiation crosslinking using gamma radiation was also used. The components of the biopolymer composite were a matrix of PLA and PHBV and the filler was natural cellulose fibers in a constant percentage volume of 20%. Test specimens were made from compounds of prepared biopolymer structures, on which selected tests had been performed to evaluate the properties and mechanical characterization of biopolymer composites. Electron microscopy was used to evaluate the failure and characterization of fracture surfaces of biocomposites.

• Klíčová slova
• biopolymer, biopolymer composite, fracture surface, mechanical behavior, natural fibers, polymer, radiation crosslinking, surface modification,
• Publikační typ
• časopisecké články MeSH

This work studies the impact of the electrostatic interaction between analyte molecules and silver nanoparticles (Ag NPs) on the intensity of surface-enhanced Raman scattering (SERS). For this, we fabricated nanostructured plasmonic films by immobilization of Ag NPs on glass plates and functionalized them by a set of differently charged hydrophilic thiols (sodium 2-mercaptoethyl sulfonate, mercaptopropionic acid, 2-mercaptoethanol, 2-(dimethylamino)ethanethiol hydrochloride, and thiocholine) to vary the surface charge of the SERS substrate. We used two oppositely charged porphyrins, cationic copper(II) tetrakis(4-N-methylpyridyl) porphine (CuTMpyP4) and anionic copper(II) 5,10,15,20-tetrakis(4-sulfonatophenyl)porphine (CuTSPP4), with equal charge value and similar structure as model analytes to probe the SERS signal. Our results indicate that the SERS spectrum intensity strongly, up to complete signal disappearance, correlates with the surface charge of the substrate, which tends to be negative. Using the data obtained and our model SERS system, we analyzed the modification of the Ag surface by different reagents (lithium chloride, polyethylenimine, polyhexamethylene guanidine, and multicharged metal ions). Finally, all those surface modifications were tested using a negatively charged oligonucleotide labeled with Black Hole Quencher dye. Only the addition of copper ions into the analyte solution yielded a good SERS signal. Considering the strong interaction of copper ions with the oligonucleotide molecules, we suppose that inversion of the analyte charge played a key role in this case, instead of a change of charge of the substrate surface. Changing the charge of analytes could be a promising way to get clear SERS spectra of negatively charged molecules on Ag SERS-active supports.

• Klíčová slova
• electrostatic interaction, oligonucleotides, porphyrin, silver nanoparticles, substrate modification, surface-enhanced Raman spectroscopy (SERS),
• Publikační typ
• časopisecké články MeSH

The genes hsdM and hsdS for M. EcoKI modification methyltransferase and the complete set of hsdR, hsdM and hsdS genes coding for R. EcoKI restriction endonuclease, both with and without a temperature-sensitive (ts) mutation in hsdS gene, were cloned in pBR322 plasmid and introduced into E. coli C (a strain without a natural restriction-modification (R-M) system). The strains producing only the methyltransferase, or together with the endonuclease, were thus obtained. The hsdSts-1 mutation, mapped previously in the distal variable region of the hsdS gene with C1 245-T transition has no effect on the R-M phenotype expressed from cloned genes in bacteria grown at 42 degrees C. In clones transformed with the whole hsd region an alleviation of R-M functions was observed immediately after the transformation, but after subculture the transformants expressed the wild-type R-M phenotype irrespective of whether the wild-type or the mutant hsdS allele was present in the hybrid plasmid. Simultaneous overproduction of HsdS and HsdM subunits impairs the ts effect of the hsdSts-1 mutation on restriction and modification.

• MeSH
• bakteriální geny genetika   MeSH
• bakteriální transformace MeSH
• Escherichia coli enzymologie   genetika   MeSH
• fenotyp MeSH
• místně specifická DNA-methyltransferasa (adenin-specifická) biosyntéza   genetika   fyziologie   MeSH
• mutace MeSH
• plazmidy analýza   genetika   MeSH
• restrikční enzymy biosyntéza   genetika   fyziologie   MeSH
• teplota MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA modification methylase EcoKI MeSH Prohlížeč
• endodeoxyribonuclease EcoKI MeSH Prohlížeč
• místně specifická DNA-methyltransferasa (adenin-specifická) MeSH
• restrikční enzymy MeSH

Effectively optimized and reproducible procedure for monitoring the composition of type I restriction-modification endonucleases EcoKI and EcoR124I by non-equilibrium pH gradient two-dimensional (2-D) gel electrophoresis is described. Three subunits of the enzyme complex, which widely differ from one another in their isoelectric points and molar mass, were identified in crude cell extracts of E. coli. For the first time all three subunits of both EcoKI and EcoR124I were detected as distinct spots on a single 2-D gel. A sensitive immunoblotting procedure was suggested suitable for routine use in determining the identity of individual subunits. Potential application of this method for detailed studies of regulation of the function and stoichiometry of the enzyme complexes is discussed.

• MeSH
• 2D gelová elektroforéza MeSH
• DNA restrikčně-modifikační enzymy chemie   MeSH
• Escherichia coli enzymologie   MeSH
• izoelektrický bod MeSH
• místně specifická DNA-methyltransferasa (adenin-specifická) chemie   MeSH
• molekulová hmotnost MeSH
• restrikční endonukleasy typu I chemie   MeSH
• restrikční enzymy chemie   MeSH
• western blotting MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA modification methylase EcoKI MeSH Prohlížeč
• DNA restrikčně-modifikační enzymy MeSH
• EcoR124 modification methylase type I MeSH Prohlížeč
• endodeoxyribonuclease EcoKI MeSH Prohlížeč
• endodeoxyribonuclease EcoR124I MeSH Prohlížeč
• místně specifická DNA-methyltransferasa (adenin-specifická) MeSH
• restrikční endonukleasy typu I MeSH
• restrikční enzymy MeSH