SERS-substrates based on ZnO nanoflowers prepared by green synthesis.

ZnO nanoparticles (NPs) with a flower-like morphology, synthesized by an affordable colloidal route using an aqueous fungi extract of Ganoderma lucidum as a reducing agent and stabilizer, are investigated as SERS-substrate. Each "flower" has large effective surface that is preserved at packing particles into a dense film and thus exhibits an advantageous property for SERS and similar sensing applications. The mycoextract used in our low-cost and green synthesis as surface stabilizer allows subsequent deposition of metal NPs or layers. One type of SERS substrates studied here was ZnO NPs decorated in situ in the solution by Ag NPs, another type was prepared by thermally evaporating Ag layer on the ZnO NP film on a substrate. A huge difference in the enhancement of the same analyte in the solution and in the dried form is found and discussed. Detection down to 10-7 M of standard dye analytes such as rhodamine 6G and methylene blue was achieved without additional optimization of the SERS substrates. The observed SERS-activity demonstrate the potential of both the free-standing flower-like ZnO NPs and thereof made dense films also for other applications where large surface area accessible for the external agent is crucial, such as catalysis or sensing.

Transient drought during flowering modifies the grain proteome of bread winter wheat.

Drought is among the most limiting factors for sustainable agricultural production. Water shortage at the onset of flowering severely affects the quality and quantity of grain yield of bread wheat (Triticum aestivum). Herein, we measured oxidative stress and photosynthesis-related parameters upon applying transient drought on contrasting wheat cultivars at the flowering stage of ontogenesis. The sensitive cultivar (Darunok Podillia) showed ineffective water management and a more severe decline in photosynthesis. Apparently, the tolerant genotype (Odeska 267) used photorespiration to dissipate excessive light energy. The tolerant cultivar sooner induced superoxide dismutase and showed less inhibited photosynthesis. Such a protective effect resulted in less affected yield and spectrum of seed proteome. The tolerant cultivar had a more stable gluten profile, which defines bread-making quality, upon drought. Water deficit caused the accumulation of medically relevant proteins: (i) components of gluten in the sensitive cultivar and (ii) metabolic proteins in the tolerant cultivar. We propose specific proteins for further exploration as potential markers of drought tolerance for guiding efficient breeding: thaumatin-like protein, 14-3-3 protein, peroxiredoxins, peroxidase, FBD domain protein, and Ap2/ERF plus B3 domain protein.

Bactericidal activity of Ag nanoparticles biosynthesized from Capsicum annuum pericarps against phytopathogenic Clavibacter michiganensis.

Metallic nanoparticles of different compositions have already found numerous applications in various branches of industry, agriculture, and medicine. Given the well-known antibacterial activity of Ag, silver nanoparticles (AgNPs) are constantly being investigated for their promising ability to fight antibiotic-resistant pathogens. A promising candidate for AgNPs biosynthesis is chili pepper Capsicum annuum, cultivated worldwide and known for accumulating significant amounts of active substances. Phytochemical screening of aqueous extract of C. annuum pericarps demonstrated accumulation of 4.38 mg/g DW of total capsaicinoids, 14.56 mg GAE/g DW of total phenolic compounds, 1.67 mg QE/g DW of total flavonoids, and 1.03 mg CAE/g DW of total phenolic acids. All determined aromatic compounds carry various active functional groups, which effectively participate in the biosynthesis of AgNPs and are characterized by high antioxidant potential. Therefore, the present research focused on the facile, quick, and effective procedure for the biosynthesis of AgNPs, which were analyzed for their morphology such as shape and size through UV-visible, Fourier-transform infrared spectroscopy (FTIR) assays, and scanning electron microscopy. We found that the AgNPs biosynthesis resulted in changes in FTIR spectra, depicting the rearrangement of numerous functional groups, while the nanoparticles themselves were shown to be stable, spherical, 10-17 nm in size. Also we investigated the antibacterial properties of biosynthesized AgNPs, obtained with C. annuum fruit extracts, against a common phytopathogen Clavibacter michiganensis subsp. michiganensis. As was shown by zone inhibition assay, AgNPs showed dose-dependent 5.13-6.44 cm antibacterial activity, greatly exceeding the 4.98 cm inhibition area, produced by the precursor salt, AgNO3.

Lake microbiome and trophy fluctuations of the ancient hemp rettery.

Lake sediments not only store the long-term ecological information including pollen and microfossils but are also a source of sedimentary DNA (sedDNA). Here, by the combination of traditional multi-proxy paleolimnological methods with the whole-metagenome shotgun-sequencing of sedDNA we were able to paint a comprehensive picture of the fluctuations in trophy and bacterial diversity and metabolism of a small temperate lake in response to hemp retting, across the past 2000 years. Hemp retting (HR), a key step in hemp fibre production, was historically carried out in freshwater reservoirs and had a negative impact on the lake ecosystems. In Lake Slone, we identified two HR events, during the late stage of the Roman and Early Medieval periods and correlated these to the increased trophy and imbalanced lake microbiome. The metagenomic analyses showed a higher abundance of Chloroflexi, Planctomycetes and Bacteroidetes and a functional shift towards anaerobic metabolism, including degradation of complex biopolymers such as pectin and cellulose, during HR episodes. The lake eutrophication during HR was linked to the allochthonous, rather than autochthonous carbon supply-hemp straws. We also showed that the identification of HR based on the palynological analysis of hemp pollen may be inconclusive and we suggest the employment of the fibre count analysis as an additional and independent proxy.

ZnO and Ag NP-decorated ZnO nanoflowers: green synthesis using Ganoderma lucidum aqueous extract and characterization.

Fungi produce and excrete various proteins, enzymes, polysaccharides, and secondary metabolites, which may be used as media for the "green" synthesis of metal and semiconductor nanoparticles (NPs). ZnO NPs with a flower-like morphology were synthesized by an affordable colloidal route, using an aqueous extract of Ganoderma lucidum as a reducing agent and stabilizer. Each individual "flower" has a large effective surface, which is preserved when the particles are close packed into a dense film, which is advantageous for numerous applications. The phonon Raman spectrum and X-ray diffraction (XRD) pattern prove the high crystallinity of the NPs, with the distinct pattern of a hexagonal (wurtzite) lattice, negligible residual stress, and a crystallite size of 12-14 nm determined from the XRD. The photoluminescence (PL) spectrum of the as-synthesized ZnO NPs contains a structured defect-related feature in the violet-blue range, while the green PL, common for nanostructures synthesized by "green" routes, is very weak. By applying dimethylsulfoxide as an additional passivating agent, the excitonic (UV) PL band was activated without enhancement of the defect-related features. Ag NP-decorated ZnO flowers were synthesized by subsequent silver reduction by pepper extract. The ZnO/Ag NPs exhibited efficient surface-enhanced Raman scattering (SERS) of a standard dye analyte, rhodamine 6G, ensuring the feasibility of other applications that require close contact of ZnO/Ag to other nanostructures or molecules to realize the energy of the charge transfer.

RIBO-seq in Bacteria: a Sample Collection and Library Preparation Protocol for NGS Sequencing.

The ribosome profiling technique (RIBO-seq) is currently the most effective tool for studying the process of protein synthesis in vivo. The advantage of this method, in comparison to other approaches, is its ability to monitor translation by precisely mapping the position and number of ribosomes on a mRNA transcript. In this article, we describe the consecutive stages of sample collection and preparation for RIBO-seq method in bacteria, highlighting the details relevant to the planning and execution of the experiment. Since the RIBO-seq relies on intact ribosomes and related mRNAs, the key step is rapid inhibition of translation and adequate disintegration of cells. Thus, we suggest filtration and flash-freezing in liquid nitrogen for cell harvesting with an optional pretreatment with chloramphenicol to arrest translation in bacteria. For the disintegration, we propose grinding frozen cells with mortar and pestle in the presence of aluminum oxide to mechanically disrupt the cell wall. In this protocol, sucrose cushion or a sucrose gradient ultracentrifugation for monosome purification is not required. Instead, mRNA separation using polyacrylamide gel electrophoresis (PAGE) followed by the ribosomal footprint excision (28-30 nt band) is applied and provides satisfactory results. This largely simplifies the method as well as reduces the time and equipment requirements for the procedure. For library preparation, we recommend using the commercially available small RNA kit for Illumina sequencing from New England Biolabs, following manufacturer's guidelines with some degree of optimization. The resulting cDNA libraries present appropriate quantity and quality required for next generation sequencing (NGS). Sequencing of the libraries prepared according to the described protocol results in 2 to 10 mln uniquely mapped reads per sample providing sufficient data for comprehensive bioinformatic analysis. The protocol we present is quick and relatively easy and can be performed with standard laboratory equipment.

Effect of Zinc and Copper Nanoparticles on Drought Resistance of Wheat Seedlings.

The effect of a colloidal solution of Cu,Zn-nanoparticles on pro-oxidative/antioxidative balance and content of photosynthetic pigments and leaf area of winter wheat plants of steppe (Acveduc) and forest-steppe (Stolichna) ecotypes was investigated in drought conditions. It has been shown that Cu,Zn-nanoparticles decreased the negative effect of drought action upon plants of steppe ecotype Acveduc. In particular, increased activity of antioxidative enzymes reduced the level of accumulation of thiobarbituric acid reactive substances (TBARS) and stabilized the content of photosynthetic pigments and increased relative water content in leaves. Colloidal solution of Cu,Zn-nanoparticles had less significant influence on these indexes in seedlings of the Stolichna variety under drought.

Colloidal Nanomolybdenum Influence upon the Antioxidative Reaction of Chickpea Plants (Cicer arietinum L.).

The use of colloidal solutions of metals as micronutrients enhances plant resistance to unfavorable environmental conditions and ensures high yields of food crops. The purpose of the study was a comparative evaluation of presowing treatment with nanomolybdenum and microbiological preparation impact upon the development of adaptive responses in chickpea plants. Oxidative processes did not develop in all variants of the experiment but in variants treated with microbial preparation, and joint action of microbial and nanopreparations even declined, as evidenced by the reduction of thiobarbituric acid reactive substances in photosynthetic tissues by 15 %. The activity of superoxide dismutase increased (by 15 %) in variant "nanomolybdenum" and joint action "microbial + nanomolybdenum," but it decreased by 20 % in variants with microbial preparation treatment. The same dependence was observed in changes of catalase activity. Antioxidant status factor, which takes into account the ratio of antioxidant to pro-oxidant, was the highest in variants with joint action of microbial preparation and nanomolybdenum (0.7), the lowest in variants with microbial treatment only (0.1). Thus, the results show that the action of nanoparticles of molybdenum activated antioxidant enzymes and decreased oxidative processes, thus promoting adaptation of plants.

Impact of Metal Nanoform Colloidal Solution on the Adaptive Potential of Plants.

Nanoparticles are a known cause of oxidative stress and so induce antistress action. The latter property was the purpose of our study. The effect of two concentrations (120 and 240 mg/l) of nanoform biogenic metal (Ag, Cu, Fe, Zn, Mn) colloidal solution on antioxidant enzymes, superoxide dismutase and catalase; the level of the factor of the antioxidant state; and the content of thiobarbituric acid reactive substances (TBARSs) of soybean plant in terms of field experience were studied. It was found that the oxidative processes developed a metal nanoparticle pre-sowing seed treatment variant at a concentration of 120 mg/l, as evidenced by the increase in the content of TBARS in photosynthetic tissues by 12 %. Pre-sowing treatment in a double concentration (240 mg/l) resulted in a decrease in oxidative processes (19 %), and pre-sowing treatment combined with vegetative treatment also contributed to the reduction of TBARS (10 %). Increased activity of superoxide dismutase (SOD) was observed in a variant by increasing the content of TBARS; SOD activity was at the control level in two other variants. Catalase activity decreased in all variants. The factor of antioxidant activity was highest (0.3) in a variant with nanoparticle double treatment (pre-sowing and vegetative) at a concentration of 120 mg/l. Thus, the studied nanometal colloidal solution when used in small doses, in a certain time interval, can be considered as a low-level stress factor which according to hormesis principle promoted adaptive response reaction.