Sunflower Plants as Bioindicators of Environmental Pollution with Lead (II) Ions

In this study, the influence of lead (II) ions on sunflower growth and biochemistry was investigated from various points of view. Sunflower plants were treated with 0, 10, 50, 100 and/or 500 μM Pb-EDTA for eight days. We observed alterations in growth in all experimental groups compared with non-treated control plants. Further we determined total content of proteins by a Bradford protein assay. By the eighth day of the experiment, total protein contents in all treated plants were much lower compared to control. Particularly noticeable was the loss of approx. 8 μg/mL or 15 μg/mL in shoots or roots of plants treated with 100 mM Pb-EDTA. We also focused our attention on the activity of alanine transaminase (ALT), aspartate transaminase (AST) and urease. Activity of the enzymes increased with increasing length of the treatment and applied concentration of lead (II) ions. This increase corresponds well with a higher metabolic activity of treated plants. Contents of cysteine, reduced glutathione (GSH), oxidized glutathione (GSSG) and phytochelatin 2 (PC2) were determined by high performance liquid chromatography with electrochemical detection. Cysteine content declined in roots of plants with the increasing time of treatment of plants with Pb-EDTA and the concentration of toxic substance. Moreover, we observed ten times higher content of cysteine in roots in comparison with shoots. The observed reduction of cysteine content probably relates with its utilization for biosynthesis of GSH and phytochelatins, because the content of GSH and PC2 was similar in roots and shoots and increased with increased treatment time and concentration of Pb-EDTA. Moreover, we observed oxidative stress caused by Pb-EDTA in roots where the GSSG/GSH ratio was about 0.66. In shoots, the oxidative stress was less distinctive, with a GSSG/GSH ratio 0.14. We also estimated the rate of phytochelatin biosynthesis from the slope of linear equations plotted with data measured in the particular experimental group. The highest rate was detected in roots treated with 100 μM of Pb-EDTA. To determine heavy metal ions many analytical instruments can be used, however, most of them are only able to quantify total content of the metals. This problem can be overcome using laser induced breakdown spectroscopy, because it is able to provide a high spatial-distribution of metal ions in different types of materials, including plant tissues. Data obtained were used to assemble 3D maps of Pb and Mg distribution. Distribution of these elements is concentrated around main vascular bundle of leaf, which means around midrib

Acinetobacter silvestris sp. nov. discovered in forest ecosystems in Czechia

We investigated a taxonomically novel group of the genus Acinetobacter, which included five strains isolated from soil and water samples collected in preserved forest areas in Czechia between 2013 and 2021. The whole-genome sequences of the strains were 3.1-3.2 Mb in size, with G+C contents of 38.0-38.2mol%. Core genome-based phylogenetic analysis showed that they formed a compact and deeply branched Glade within the genus. The genomic average nucleotide identity based on BLAST/digital DNA-DNA hybridization values for the novel strains were 99.2-99.6%/95.2-98.4%, whereas those between the novel strains and the type strains of the known Acinetobacter species reached <78%/<24%. The results of the genus-wide analysis of whole-cell MALDI-TOF mass spectra supported the sharp distinctness of the group. The five strains were non-glucose acidifying. nonhaemolytic, nonproteolytic and growing at 28 degrees C. but not at 32 degrees C; they assimilated acetate, benzoate, ethanol, L-histidine, 4-hydroxybenzoate, DL-lactate and malonate but not 4-aminobutyrate, L-aspartate or 2,3-butanediol; this phenotype is unique among the known Acinetobacter species. We conclude that the five strains represent a novel environmental species, for which the name Acinetobacter silvestris sp. nov. is proposed, with the type strain ANC 4999(T) (=CCM 920(T)=CCUG 7587(T)=CNCTC 8124(T))

Formation of nucleobases in a Miller-Urey reducing atmosphere

The Miller-Urey experiments pioneered modern research on the molecular origins of life, but their actual relevance in this field was later questioned because the gas mixture used in their research is considered too reducing with respect to the most accepted hypotheses for the conditions on primordial Earth. In particular, the production of only amino acids has been taken as evidence of the limited relevance of the results. Here, we report an experimental work, combined with state-of-the-art computational methods, in which both electric discharge and laser-driven plasma impact simulations were carried out in a reducing atmosphere containing NH 3 + CO. We show that RNA nucleobases are synthesized in these experiments, strongly supporting the possibility of the emergence of biologically relevant molecules in a reducing atmosphere. The reconstructed synthetic pathways indicate that small radicals and formamide play a crucial role, in agreement with a number of recent experimental and theoretical results. The following explorations showed that a broad array of amino acids could be synthesized, but there was no evidence that all of the fundamental molecules of the RNA genetic code could be produced alongside others in this type of experiment (2-5). Additionally, the significant persistence of reducing atmospheres in a geological timescale has been seriously debated (6). Finally, many scientists have claimed that this experiment is not related to early-Earth conditions and does not provide fundamental building blocks (i.e., nucleobases) important for the evolution of early life possibly based on RNA (7-13). In 2001, Saladino, Di Mauro, and coworkers During the past decade, comets (39), HCN hydrolysis (40), chemistry in interstellar space (41), reducing atmospheres (42), or ammonium formate dehydration (43) have been proposed as sources of formamide. However, in most cases, the exact chemistry of such systems has not been well explored either experimentally or theoretically. Moreover, the plausibility and relation to a prebiotic environment is also questioned. Using the large laser facility at the terrawatt Prague Asterix Laser System, we comprehensively explored asteroid shock wave impact plasma, in addition to electric discharge, in a simple reducing mixture of NH 3 + CO and H 2 O. The formamide molecule does not directly play the role of starting substrate, but it is rather a suspected intermediate of reactions leading from simple model prebiotic mixtures to biomolecules. The results are compared with similar experiments, in which formamide is the starting compound. The chemistry is also mapped using state-of-the-art ab initio molecular-dynamics simulations. We focused our effort on two environments relevant to prebiotic chemistry: (i) transformation of an atmosphere exposed a shock wave induced by an extraterrestrial body and the resulting impact Significance The study shows that Miller-Urey experiments produce RNA nucleobases in discharges and laser-driven plasma impact simulations carried out in a simple prototype of reducing atmosphere containing ammonia and carbon monoxide. We carried out a self-standing description of chemistry relevant to hypothesis of abiotic synthesis of RNA nucleobases related to early-Earth chemical evolution under reducing conditions. The research addresses the chemistry of simple-model reducing atmosphere (NH 3 + CO + H 2 O) and the role of formamide as an intermediate of nucleobase formation in Miller-Urey experiment. The explorations combine experiments performed using modern techniques of large, high-power shock wave plasma generation by hall terawatt lasers, electric discharges, and state-of-the-art ab initio free-energy calculations

Formation of nucleobases in a Miller-Urey reducing atmosphere

The Miller-Urey experiments pioneered modern research on the molecular origins of life, but their actual relevance in this field was later questioned because the gas mixture used in their research is considered too reducing with respect to the most accepted hypotheses for the conditions on primordial Earth. In particular, the production of only amino acids has been taken as evidence of the limited relevance of the results. Here, we report an experimental work, combined with state-of-the-art computational methods, in which both electric discharge and laser-driven plasma impact simulations were carried out in a reducing atmosphere containing NH 3 + CO. We show that RNA nucleobases are synthesized in these experiments, strongly supporting the possibility of the emergence of biologically relevant molecules in a reducing atmosphere. The reconstructed synthetic pathways indicate that small radicals and formamide play a crucial role, in agreement with a number of recent experimental and theoretical results. The following explorations showed that a broad array of amino acids could be synthesized, but there was no evidence that all of the fundamental molecules of the RNA genetic code could be produced alongside others in this type of experiment (2-5). Additionally, the significant persistence of reducing atmospheres in a geological timescale has been seriously debated (6). Finally, many scientists have claimed that this experiment is not related to early-Earth conditions and does not provide fundamental building blocks (i.e., nucleobases) important for the evolution of early life possibly based on RNA (7-13). In 2001, Saladino, Di Mauro, and coworkers During the past decade, comets (39), HCN hydrolysis (40), chemistry in interstellar space (41), reducing atmospheres (42), or ammonium formate dehydration (43) have been proposed as sources of formamide. However, in most cases, the exact chemistry of such systems has not been well explored either experimentally or theoretically. Moreover, the plausibility and relation to a prebiotic environment is also questioned. Using the large laser facility at the terrawatt Prague Asterix Laser System, we comprehensively explored asteroid shock wave impact plasma, in addition to electric discharge, in a simple reducing mixture of NH 3 + CO and H 2 O. The formamide molecule does not directly play the role of starting substrate, but it is rather a suspected intermediate of reactions leading from simple model prebiotic mixtures to biomolecules. The results are compared with similar experiments, in which formamide is the starting compound. The chemistry is also mapped using state-of-the-art ab initio molecular-dynamics simulations. We focused our effort on two environments relevant to prebiotic chemistry: (i) transformation of an atmosphere exposed a shock wave induced by an extraterrestrial body and the resulting impact Significance The study shows that Miller-Urey experiments produce RNA nucleobases in discharges and laser-driven plasma impact simulations carried out in a simple prototype of reducing atmosphere containing ammonia and carbon monoxide. We carried out a self-standing description of chemistry relevant to hypothesis of abiotic synthesis of RNA nucleobases related to early-Earth chemical evolution under reducing conditions. The research addresses the chemistry of simple-model reducing atmosphere (NH 3 + CO + H 2 O) and the role of formamide as an intermediate of nucleobase formation in Miller-Urey experiment. The explorations combine experiments performed using modern techniques of large, high-power shock wave plasma generation by hall terawatt lasers, electric discharges, and state-of-the-art ab initio free-energy calculations

Acinetobacter amyesii sp. nov., widespread in the soil and water environment and animals

We studied a novel taxon of the genus Acinetobacter, which comprised six strains collected in Czechia, Germany, Indonesia and Turkey between 2015 and 2021. The organisms were isolated from environmental soil, water samples and cow faeces. Their genome sizes varied between 3.3 and 3.5 Mb, with a G+C content of 40.4-40.8mol%. Based on genus--wide core genome analysis, the taxon formed a distinct clade, with Acinetobacter gandensis being the phylogenetically closest related species. The intrataxon genomic average nucleotide identity based on blast (ANIb) and digital DNA-DNA hybridization (dDDH) values reached 95.3-97.4% and 62.5-77.8 %, respectively, whereas its ANIb/dDDH values against the known Acinetobacter type strains were =82.7%/=25.7%. Cluster analysis of whole--cell MALDI--TOF mass spectra corroborated the distinctness and cohesiveness of the taxon. The novel strains were non--glucose--oxidizing, non--haemolytic and non--proteolytic, growing at up to 37-41 degrees C but not at 44 degrees C and utilizing 8-10 of the 36 carbon sources tested. Growth on glutarate, tricarballylate and at 37 degrees C combined with the inability to assimilate 4--aminobutyrate and d--malate differentiated them from all validly named Acinetobacter species. The inspection of genome sequences in the NCBI database revealed the existence of numerous strains conspecific with this group, which were collected from pig faeces and environmental samples in China. We conclude that the taxon represents an ecologically and geographically widespread species, for which we propose the name Acinetobacter amyesii sp. nov., with ANC 5579T (= CCM 9242T=CCUG 76274T=CNCTC 8134T) as the type strain

Determination of Plant Thiols by Liquid Chromatography Coupled with Coulometric and Amperometric Detection in Lettuce Treated by Lead(II) Ions

The main aim of this paper is to utilize high performance liquid chromatography with electrochemical detection for determination of thiols content in plants tissues of lettuce treated with lead (II) ions (0, 0.5 and 1 mM). We used two HPLC-ED instruments: HPLC coupled with one channel amperomterich detector and HPLC coupled with twelve channel coulometric detector to detect simultaneously twelve thiols. The detection limits of thiols measured by CoulArray detector were about two magnitudes lower n comparison to those measured by Coulochem III detector and were from tens to hundreds pM. Under the optimal conditions, we utilized HPLC-CoulArray detector for analysis of tissues from lettuce plants. In addition, distribution and accumulation of lead ions with high spatial resolution was monitored using laser induced breakdown spectroscopy