•Due to climate change the surface of floodplain water bodies decreases substantially.•The share of small lakes and ponds increases.•Small floodplain lakes may be a substantial source of CO2 ...emission.•Carbon is buried mostly in insoluble forms.
Small floodplain lakes (SFLs), characterized by their diminutive size (<10,000 m2), have been consistently overlooked in assessments of organic carbon (C) stock and the impacts of climate changes. This study aims to ascertain both the quantity and quality of carbon stored within the sediments of SFLs. Furthermore, we endeavour to evaluate the influence of ongoing climate change on the floodplain lake structure within the continental humid climate zone on the example of the Vistula River valley and estimate the CO2 emission from dry floodplain lakes. The sedimentary organic carbon content (TOC) ranged from 2.3–64 g kg−1, averaging at 3.4 g kg−1. Consequently, the sediments in the analysed SFLs of the river section potentially harbour up to 5,785 Mg TOC. Notably, the abundance of easily soluble carbon fractions (humic and fulvic acids) was relatively low (∼15 %), implying a stable immobilization of organic C compounds and minimal impact of sediments on water quality. Satellite imagery analysis for the years 2017–2020 revealed a 31 % reduction in the total lake surface area within a 100-km-long segment of the Vistula River. The decreasing surface area of floodplain lakes and rising mean air temperatures increase CO2 emissions and have an additional impact on climate warming. Our research underscores that investigating lake C storage concerning climate change demands a nuanced approach. While higher temperatures stimulate primary production, the reduction in lake surface area and the escalating role of small lakes, such as SFLs, in C storage should be paramount considerations.
This study covers the western part of Poland’s loess Nałęczów Plateau (Kazimierz Dolny, Zbędowice). Mass movements in the Lublin Upland occur during periods of increased precipitation or after a ...snowy and cold winter. To date, there are no comprehensive studies on active (precipitation, hydrology, vegetation, land use, anthropogenic factors) or passive factors (lithology, slope angle) causing such geohazards in this region. This area’s formations are characterised by high sensitivity to even small changes in moisture content; thus, their geotechnical parameters deteriorate as a result of precipitation or rising groundwater levels. The calculations in this study were chosen to determine the time necessary for ground response to external factors, in addition to determining the impact of these factors on decreases in the factor of safety (FS). Based on calculations in GeoStudio software, the impacts of rainfall totals and duration on slope failure, interpreted as an event where the FS falls below 1.0, were analysed. Accordingly, the threshold rainfall value was determined as the total rainfall at the time of slope failure. The study’s results indicate that loess covers are characterised by average water permeability, relatively high internal friction angles and low cohesion, which, combined with high slope inclination, favour landslide formation even when the slope is only partially saturated. The most unfavourable stability conditions occur at the beginning of spring, indicating that loess stability is significantly affected by snowmelt and precipitation at the beginning of the vegetation season, as well as the occurrence of episodic intense precipitation during the summer.
Streptomyces are soil bacteria with complex life cycle. During sporulation Streptomyces linear chromosomes become highly compacted so that the genetic material fits within limited spore volume. The ...key players in this process are nucleoid-associated proteins (NAPs). Among them, HU (heat unstable) proteins are the most abundant NAPs in the cell and the most conserved in bacteria. HupS, one of the two HU homologues encoded by the Streptomyces genome, is the best-studied spore-associated NAP. In contrast to other HU homologues, HupS contains a long, C-terminal domain that is extremely rich in lysine repeats (LR domain) similar to eukaryotic histone H2B and mycobacterial HupB protein. Here, we have investigated, whether lysine residues in HupS are posttranslationally modified by reversible lysine acetylation. We have confirmed that Streptomyces venezuelae HupS is acetylated in vivo. We showed that HupS binding to DNA in vitro is controlled by the acetylation. Moreover, we identified that CobB1, one of two Sir2 homologues in Streptomyces, controls HupS acetylation levels in vivo. We demonstrate that the elimination of CobB1 increases HupS mobility, reduces chromosome compaction in spores, and affects spores maturation. Thus, our studies indicate that HupS acetylation affects its function by diminishing DNA binding and disturbing chromosome organization.
One-dimensional transition metal materials are promising supports for precious metals used in energy production processes. Due to their electrochemical properties, 3d-group metals (such as Ni, Co, ...and Fe) can actively interact with catalysts by a strong metal–support interaction. This study shows that changing the Ni:Co ratio makes it possible to modulate the structure of the catalyst supports, which, in turn, provides a tool for designing their electrical and electrochemical properties. For example, Ni1–Co9 shows the highest electrical conductivity (5.8–10–4 S/cm) among all of the materials examined. On the contrary, the Pd@Ni7–Co3 system presents the highest mass activity (>2000 mA mg–1) at 0.7 V, exceeding by several times that of commercial Pt/C (>300 mA mg–1) at the same potential. Our study opens the gateway for applications of bimetallic transition metal nanowires in catalytic conversion and energy production processes.
•The influence of nickel in ferrites on the phase transition from tetragonal to cubic.•Replacing Cu with Ni improves the catalytic activity of N2O decomposition in ferrites.•Magnetic moment values ...per formula unit are estimated to range from 1.16 μB to 1.5 μB.
The aim of this work was to obtain information about the influence of small quantities of Ni2+ ion on the structural and magnetic properties of the tetragonally distorted of Cu1−xNixFe2O4 series (with x = 0.00, 0.05, 0.1, and 0.15 respectively). The tested ferrite system was synthesized by combustion of citrate–nitrate precursors. The synchrotron X-ray diffraction measurements determined the phase transition temperatures (tetragonal → cubic) of all samples. The change of structures under the influence of temperature shows a phase transition in the range of 390 – 400 °C for x = 0.00, 330 – 370 °C for x = 0.05, 210 – 330 °C for x = 0.1 and 140 – 210 °C for x = 0.15, respectively. The initial phase transition temperature decreases linearly with the decreasing c/a ratio of the crystallographic lattice parameters for the Cu1−xNixFe2O4 oxides. Hysteresis measurements were made to determine the saturation magnetization (MS) and coercive field (µ0Hc) of the samples. The values of magnetic moments at room temperature determined from magnetization measurements are very similar to those obtained from theoretical x-ray diffraction calculations. Magnetic moment values per formula unit are estimated to range from 1.16 μB to 1.5 μB. It was found that the catalytic activity of N2O decomposition of samples increases with increasing nickel content.
Bacterial chromosome topology is controlled by topoisomerases and nucleoid-associated proteins (NAPs). While topoisomerases regulate DNA supercoiling, NAPs introduce bends or coat DNA upon its ...binding, affecting DNA loop formation. Streptomyces, hyphal, multigenomic bacteria known for producing numerous clinically important compounds, use the highly processive topoisomerase I (TopA) to remove excessive negative DNA supercoils. Elongated vegetative Streptomyces cells contain multiple copies of their linear chromosome, which remain relaxed and relatively evenly distributed. Here, we explored how TopA cooperates with HupA, an HU homologue that is the most abundant Streptomyces NAP. We verified that HupA has an increased affinity for supercoiled DNA in vivo and in vitro. Analysis of mutant strains demonstrated that HupA elimination is detrimental under high DNA supercoiling conditions. The absence of HupA, combined with decreased TopA levels, disrupted chromosome distribution in hyphal cells, eventually inhibiting hyphal growth. We concluded that increased HupA binding to DNA under elevated chromosome supercoiling conditions is critical for the preservation of chromosome organisation.
Inexpensive protic ionic liquids, synthesized from di- or triamines and excess sulfuric acid, were used as solvents and catalysts for the Beckmann rearrangement. The use of ionic liquids in place of ...oleum or sulfuric acid allowed the base neutralization step, which is required in the conventional Beckmann rearrangement, to be entirely avoided, thereby dramatically improving the atom economy. Using a biphasic water/organic solvent extraction system, it was possible to recover and reuse the ionic liquid. The proposed method was found applicable for the synthesis of a range of primary and secondary amides.
Negative DNA supercoiling allows chromosome condensation and facilitates DNA unwinding, which is required for the occurrence of DNA transaction processes, i.e., DNA replication, transcription and ...recombination. In bacteria, changes in chromosome supercoiling impact global gene expression; however, the limited studies on the global transcriptional response have focused mostly on pathogenic species and have reported various fractions of affected genes. Furthermore, the transcriptional response to long-term supercoiling imbalance is still poorly understood. Here, we address the transcriptional response to both novobiocin-induced rapid chromosome relaxation or long-term topological imbalance, both increased and decreased supercoiling, in environmental antibiotic-producing bacteria belonging to the
genus. During the
complex developmental cycle, multiple copies of GC-rich linear chromosomes present in hyphal cells undergo profound topological changes, from being loosely condensed in vegetative hyphae, to being highly compacted in spores. Moreover, changes in chromosomal supercoiling have been suggested to be associated with the control of antibiotic production and environmental stress response. Remarkably, in
, a model
species, topoisomerase I (TopA) is solely responsible for the removal of negative DNA supercoils. Using a
strain in which
transcription is under the control of an inducible promoter, we identified genes involved in the transcriptional response to long-term supercoiling imbalance. The affected genes are preferentially organized in several clusters, and a supercoiling-hypersensitive cluster (SHC) was found to be located in the core of the
chromosome. The transcripts affected by long-term topological imbalance encompassed genes encoding nucleoid-associated proteins, DNA repair proteins and transcriptional regulators, including multiple developmental regulators. Moreover, using a gyrase inhibitor, we identified those genes that were directly affected by novobiocin, and found this was correlated with increased AT content in their promoter regions. In contrast to the genes affected by long-term supercoiling changes, among the novobiocin-sensitive genes, a significant fraction encoded for proteins associated with membrane transport or secondary metabolite synthesis. Collectively, our results show that long-term supercoiling imbalance globally regulates gene transcription and has the potential to impact development, secondary metabolism and DNA repair, amongst others.
Copolymers of N-isopropylacrylamide (PNIPAM) are one of the most promising microgel materials for medical applications, especially as a drug carrier. PNIPAMs present unique properties, such as size ...variation with changing pH and/or temperature. The results of a study on the uptake and release of a dye (Orange II) by microgels of N-isopropylacrylamide copolymer with 1-vinylimidazole (P(NIPAM-co-Vim) are presented. The dye was used as a model low-molecular substance. Hydrodynamic radius (Rh) of P(NIPAM-co-Vim) particles was measured by dynamic light scattering as a function of temperature in two pH environments: acidic and basic. The dye particles contraction was monitored as a function of temperature at pH 4. The measurements of the zeta potential indicated a positive charge of P(NIPAM-co-Vim) particles at pH 4 and a negative one at pH 9. The key experiments were the internalization and the release of the dye. The effectiveness of this process was measured by UV-Vis spectroscopy on the supernatant derived from centrifuged P(NIPAM-co-Vim) suspension. At room temperature the efficiency of trapping of the dye by the microgel at pH 4 was 87%. Changing pH of a sample initially saturated with the dye from 4 to 9 led to a complete release of the trapped dye.
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