Non-toxic orange carbon dots stimulate photosynthesis and CO2 assimilation in hydroponically cultivated green beans (Phaseolus vulgaris).

Continuous increasing leaf photosynthesis may enhance plant yield. As an evolutionary property, plants use less photosynthetic capacity than is theoretically possible. Plant nanobionics is a bioengineering field that improves plant functions using nanoparticles. We applied orange carbon dots (o-CDs) onto the foliage of green beans (Phaseolus vulgaris ) grown in hydroponics to improve their photosynthetic performance and CO2 assimilation. Photosynthesis parameters, photosynthetic pigments content, total phenolic content (TPC) and antioxidative activity (TAA) were measured. Results show that photosynthetic pigments remained unchanged, while photosynthesis was improved. Both o-CDs concentrations decreased TPC and TAA. The light response curve showed higher CO2 assimilation at both o-CDs concentrations, particularly at lower light intensity. Correlation analysis confirmed increased CO2 binding and assimilation at 1mg L-1 . This study demonstrated the potential of using o-CDs as a safe biostimulator through photosynthesis increase and CO2 assimilation without toxic effects on plants. This may stimulate yield increase that paves the way for their agricultural application.

Therapeutic potential of low-molecular weight lignin model polymer fractions for treating skin lesions in animals: a pilot study.

Bacterial infections and resistance to antibiotics are increasingly severe problems. In recent years, Staphylococcus species have emerged as important pathogens in animals and humans. Current therapeutic methods against these species have serious disadvantages; therefore new agents with antibacterial potential, such as plant-based substances, are very important in therapy. We report a pilot study with new method of fractioning the dehydrogenate polymer DHP obtained from coniferyl alcohol and application of the low-MW fractions of 200-3000 Da for antibacterial activity in healing animal lesions. In vivo experiments were conducted on the dogs having a skin lesion. Dogs were treated with the suspension containing the low-MW DHP fractions as the active ingredient, in combination with alginate for 7 days. Cytological smears and microbiological analyses of the affected area were performed. Staphylococcus spp. was isolated from lesions in all dogs from our research. The results show that the low-MW DHP suspension in alginate promotes skin healing and reduction of the infection of the lesions in the affected animals. Pharmaceutical composition containing the low-MW DHP fractions exerts a soothing effect on the subject in wound treatment. Reduction in the number of bacteria by 30% and more were noticed in 6 dogs, while in 4 dogs this percentage is above 50%. No side effects were noticed. Synthesized lignin oligomers may have a significant place as antimicrobial and skin healing agents, especially since an increasing number of multidrug-resistant staphylococci are found on the skin lesions in animals.

Two-way reaction of versatile peroxidase with artificial lignin enhances low-molecular weight fractions.

In recent years, versatile peroxidase (VP) has emerged as a promising enzyme for biotechnological applications, as it can oxidize lignin without the external mediators. To gain insights into the breakdown process of artificial lignin by VP, reaction between the two was studied. Degradation products were fractionated using ultrafiltration and analyzed by RP- high performance liquid chromatography with mass detection (HPLC-MS) chromatography. Four fractions were obtained based on their molecular sizes: >10, 3-10, 1-3, and <1 kDa. Interestingly, while VP did not significantly alter the yields of these fractions, the chromatograms revealed the presence of oligomers with different molecular weights (MWs) resulting from the enzymatic activity. The VP exhibits a dual role in its enzymatic activity: both degrading and synthesizing these oligomers. This was confirmed by principal component analysis (PCA). The positive correlations were found between certain oligomers (D1 and D2, D5 and D6, as well as between D7, D10, T2, and T4), suggesting their simultaneous degradation. On the other hand, a negative correlation was found between the monomer and some oligomers (D7, D10, T2, and T4), indicating the decomposition of these oligomers into monomers. These findings shed light on the intricate interplay between VP and artificial lignin, offering valuable insights for potential applications in lignin valorization.

Intrinsic Fluorescence Markers for Food Characteristics, Shelf Life, and Safety Estimation: Advanced Analytical Approach.

Food is a complex matrix of proteins, fats, minerals, vitamins, and other components. Various analytical methods are currently used for food testing. However, most of the used methods require sample preprocessing and expensive chemicals. New analytical methods are needed for quick and economic measurement of food quality and safety. Fluorescence spectroscopy is a simple and quick method to measure food quality, without sample preprocessing. This technique has been developed for food samples due to the application of a front-face measuring setup. Fluorescent compounds-fluorophores in the food samples are highly sensitive to their environment. Information about molecular structure and changes in food samples is obtained by the measurement of excitation-emission matrices of the endogenous fluorophores and by applying multivariate chemometric tools. Synchronous fluorescence spectroscopy is an advantageous screening mode used in food analysis. The fluorescent markers in food are amino acids tryptophan and tyrosine; the structural proteins collagen and elastin; the enzymes and co-enzymes NADH and FAD; vitamins; lipids; porphyrins; and mycotoxins in certain food types. The review provides information on the principles of the fluorescence measurements of food samples and the advantages of this method over the others. An analysis of the fluorescence spectroscopy applications in screening the various food types is provided.

A fluorescence spectroscopic study of light transmission and adaxial-abaxial distribution of emitting compounds in leaves of Christmas star (Euphorbia pulcherrima).

In situ fluorescence measurements have been used to investigate relative amounts of blue-green pigments and their distributions in plant leaves from Euphorbia pulcherrima. Advantage was taken from the fact that this species has white leaves on the top, with low pigment concentrations, and green leaves on the stem with ordinary pigment concentrations. Excitation- and emission spectra below 410 nm from white leaves, where pigment absorption is low, are not distorted by self-absorption. Absorption- and reflection spectra from white and green leaves were measured using a spectrophotometer equipped with an integrating sphere. The absorption spectra were used to correct recorded fluorescence spectra for self-absorption. Self-absorption corrected photosystem fluorescence from green leaves, modeling light transmission in leaf tissue exponentially, matches to the excitation/emission spectra from white leaves, apart from small differences due to the pigment concentrations and selective scattering. The introduced exponentially decaying transmission relation also predicts that the ratio of excitation spectra from a white and green leaf is in proportion to the absorption spectrum of the green leaf, which was validated for Photosystem II particle fluorescence. This relation was also used to find a scaled absorption spectrum responsible for blue-green emission, which was assumed to originate from lignin. Excitation/emission spectra of the blue-green fluorescence were decomposed into five components and their relative amounts from adaxial and abaxial sides of the leaves have been quantified. Fluorescence lifetime measurements of the leaves, upon 403 nm excitation, revealed three decay times corresponding to the lignin fluorophores emitting in blue and green spectral region, and indicated that emissions at 500 and 550 nm may originate from the same fluorophore residing in the two physically different environments.

Mitochondrial nanomotion measured by optical microscopy.

Nanometric scale size oscillations seem to be a fundamental feature of all living organisms on Earth. Their detection usually requires complex and very sensitive devices. However, some recent studies demonstrated that very simple optical microscopes and dedicated image processing software can also fulfill this task. This novel technique, termed as optical nanomotion detection (ONMD), was recently successfully used on yeast cells to conduct rapid antifungal sensitivity tests. In this study, we demonstrate that the ONMD method can monitor motile sub-cellular organelles, such as mitochondria. Here, mitochondrial isolates (from HEK 293 T and Jurkat cells) undergo predictable motility when viewed by ONMD and triggered by mitochondrial toxins, citric acid intermediates, and dietary and bacterial fermentation products (short-chain fatty acids) at various doses and durations. The technique has superior advantages compared to classical methods since it is rapid, possesses a single organelle sensitivity, and is label- and attachment-free.

Trans-generational effect of cerium oxide-nanoparticles (nCeO2) on Chenopodium rubrum L. and Sinapis alba L. seeds.

Cerium oxide nanoparticles (nCeO2 ) are interesting nanomaterials due to their redox properties. Their wide application could result in unexpected consequences to environmental safety. Unlike acute toxicity, the trans-generational effects of carbohydrate-coated nCeO2 in the environment are still unknown. The main aim of this study was to investigate the effect of treating maternal plants of Chenopodium rubrum L. (red goosefoot) and Sinapis alba L. (white mustard) with uncoated (CeO2 ) and glucose-, levan-, or pullulan-coated nCeO2 (G-, L-, or P-CeO2 ) during seed germination on morphological and physiological characteristics of produced seeds in two subsequent generations. The plant response was studied by measuring germination percentage (Ger), total protein content (TPC), total phenolic content (TPhC), total antioxidative activity (TAA), and catalase (CAT) activity. Results showed that maternal effects of the different nCeO2 treatments persist to at least the second generation in seeds. Generally, C. rubrum was more sensitive to nCeO2 treatments than S. alba . The coated nCeO2 were more effective than uncoated ones in both plant species; L- and P-CeO2 were the most effective in S. alba , while CeO2 and G-CeO2 had a dominant impact in C. rubrum . Enhanced germination in all tested generations of S. alba seeds recommends nCeO2 for seed priming.

Using Front-Face Fluorescence Spectroscopy and Biochemical Analysis of Honey to Assess a Marker for the Level of Varroa destructor Infestation of Honey Bee (Apis mellifera) Colonies.

Varroa destructor is a parasitic mite responsible for the loss of honey bee (Apis mellifera) colonies. This study aimed to find a promising marker in honey for the bee colony infestation level using fluorescence spectroscopy and biochemical analyses. We examined whether the parameters of the honey samples' fluorescence spectra and biochemical parameters, both related to proteins and phenolics, may be connected with the level of honey bee colonies' infestation. The infestation level was highly positively correlated with the catalase activity in honey (r = 0.936). Additionally, the infestation level was positively correlated with the phenolic spectral component (r = 0.656), which was tentatively related to the phenolics in honey. No correlation was found between the diastase activity in honey and the colonies' infestation level. The results indicate that the catalase activity in honey and the PFC1 spectral component may be reliable markers for the V. destructor infestation level of the colonies. The obtained data may be related to the honey yield obtained from the apiaries.

Synthesis and characterization of luminescent Cu2+-doped fluorapatite nanocrystals as potential broad-spectrum antimicrobial agents.

Nanomaterials based on metal-doped fluorapatite (FAP) have attracted considerable interest as potential next-generation antimicrobial agents. In this study, Cu2+-doped FAP nanocrystals have been successfully synthesized by a neutralization method at room temperature. Their structural, optical, antimicrobial, and hemcompatible properties have been investigated. XRD, FTIR, FESEM, and N2 adsorption-desorption studies indicate the formation of single-phase FAP mesoporous nanopowders, composed of rod-like particles. TEM images confirmed the formation of nanorodes with a length of 60 nm and a width of about 18 nm. Rietveld analysis shows that the Cu2+ ions preferentially substitute Ca2 (6 h) sites in the hexagonal fluorapatite crystal structure. Fluorescence spectroscopy accompanied by MCR-ALS method confirms substitution of Cu2+ ions in FAP crystal lattice with extracting additional d-d band transition at green color from FAP broadband self-activated luminescence in violet-blue color. Antimicrobial studies conducted on Staphylococcus aureus, Escherichia coli and Micrococcus lysodeikticus showed that FAP nanopowder with the highest Cu2+ content have strong bacteriostatic action on Staphylococcus aureus bacterial strain in mediums containing nutrition matters. In addition, this sample in comparison to pure FAP achieved a high percentage of relative reduction of bacterial population for all three species, being >90% in most cases. Fungistatic action is noticed too, throwgh the slowing down mycelium growth of fungus Aspergillus niger, Aspergillus flavus and Penicillium roqueforti and reduction of sporulation of Aspergillus niger species. Cu2+-doped FAP nanocrystals shows a synergistic antimicrobial effect with Cu2+ and F- ions. Concerning the potential biomedical applications, the hemolysis ratios of the Cu2+-doped FAP samples were below 5%. The obtained results pointed out the possible use of the synthesized nanocrystals as broad-spectrum antimicrobial agents for various biomedical and health care preparations.

S, N-doped carbon dots-based cisplatin delivery system in adenocarcinoma cells: Spectroscopical and computational approach.

S and N-doped carbon dots (S-CDs and N-CDs) and their cisplatin (cis-Pt) derivatives. (S-CDs@cis-Pt and N-CDs@cis-Pt) were tested on two ovarian cancer cell lines: A2780 and A2780 cells resistant to cis-Pt (A2780R). Several spectroscopic techniques were employed to check S-CDs@cis-Pt and N-CDs@cis-Pt: solid- and solution-state nuclear magnetic resonance, matrix-assisted laser desorption, ionization time-of-flight mass spectrometry, and X-ray photoelectron spectroscopy. In addition, synchrotron-based Fourier Transformed Infrared spectro-microscopy was used to evaluate the biochemical changes in cells after treatment with cis-Pt, S-CDs, N-CDs, or S-CDs@cis-Pt and N-CDs@cis-Pt, respectively. Computational chemistry was applied to establish the model for the most stable bond between S-CDs and N-CDs and cis-Pt. The results revealed the successful modification of S-CDs and N-CDs with cis-Pt and the formation of a stable composite system that can be used for drug delivery to cancer cells and likewise to overcome acquired cis-Pt resistance. Nanoparticle treatment of A2780 and A2780R cells led to the changes in their structure of lipids, proteins, and nucleic acids depending on the treatment. The results showed the S-CDs@cis-Pt and N-CDs@cis-Pt might be used in the combination with cis-Pt to treat the adenocarcinoma, thus having a potential to be further developed as drug delivery systems.

Fluorescence spectroscopy and multispectral imaging for fingerprinting of aflatoxin-B1 contaminated (Zea mays L.) seeds: a preliminary study.

Cereal seeds safety may be compromised by the presence of toxic contaminants, such as aflatoxins. Besides being carcinogenic, they have other adverse health effects on humans and animals. In this preliminary study, we used two non-invasive optical techniques, optical fiber fluorescence spectroscopy and multispectral imaging (MSI), for discrimination of maize seeds naturally contaminated with aflatoxin B1 (AFB1) from the uncontaminated seeds. The AFB1-contaminated seeds exhibited a red shift of the emission maximum position compared to the control samples. Using linear discrimination analysis to analyse fluorescence data, classification accuracy of 100% was obtained to discriminate uncontaminated and AFB1-contaminated seeds. The MSI analysis combined with a normalized canonical discriminant analysis, provided spectral and spatial patterns of the analysed seeds. The AFB1-contaminated seeds showed a 7.9 to 9.6-fold increase in the seed reflectance in the VIS region, and 10.4 and 12.2-fold increase in the NIR spectral region, compared with the uncontaminated seeds. Thus the MSI method classified successfully contaminated from uncontaminated seeds with high accuracy. The results may have an impact on development of spectroscopic non-invasive methods for detection of AFs presence in seeds, providing valuable information for the assessment of seed adulteration in the field of food forensics and food safety.

Lignin and organic free radicals in maize (Zea mays L.) seeds in response to aflatoxin B1 contamination: an optical and EPR spectroscopic study.

BACKGROUND: Aflatoxin B1 (AFB1 ) is the most dangerous of the mycotoxins that contaminate cereal seeds naturally. A stress lignin formation is linked with the accumulation of reactive oxygen species causing a change in the redox status and formation of stable organic radicals, constituting the first layer of defense. The relationship between AFB1 and changes in lignin organic free radicals in seeds is not known, nor is the part of the seed that is more targeted. Using optical and electron paramagnetic resonance spectroscopy, we investigated AFB1 -induced changes in lignin and organic free radicals in seeds, and whether the inner and outer seed fractions differ in response to increasing AFB1 . RESULTS: Different changes in the content of lignin and free radicals with increasing AFB1 concentrations were observed in the two seed fractions. There was a significant positive linear correlation (R = 0.9923, P = 0.00005) between lignin content and AFB1 concentration in the outer fraction, and no correlation between the lignin content and the AFB1 concentration in the inner fraction. We found a positive correlation between the area of the green spectral emission component (C4) and the AFB1 concentration in the outer fraction. CONCLUSIONS: To the best of our knowledge, the results showed, for the first time, that maize seed fractions respond differently to aflatoxin with regard to their lignin and organic free radical content. Lignin content and (C4) area may be reliable indicators for the screening of lignin changes against AFB1 content in the seeds, and thus for seed protection capacity. © 2021 Society of Chemical Industry.

Influence of silicon on polymerization process during lignin synthesis. Implications for cell wall properties.

Silicon (Si) is considered a beneficial element for plants, mostly accumulating in cell walls, where its location and content are primed by the chemistry and structure of lignin. It is unrevealed how Si interacts with the process of lignin formation in the CWs. We studied, in an in vitro system, the interaction of SiO2 with the peroxidase-catalyzed polymerization of a lignin monomer into the lignin model compound, imitating conditions of the last step of lignin formation. FTIR and fluorescence spectroscopy and microscopy showed that Si is bound to the final polymer, and the structure of the Si-DHP differs from pure DHP. Fluorescence spectroscopy showed that Si does not bind to the monomers, so Si probably inhibits the formation of the larger lignin fragments, as evidenced by HPLC-DAD, by binding to dimmers formed during DHP synthesis. The structural changes of the polymer are related to the changed proportion of the fractions of various MW. The enzyme catalyzing DHP synthesis was not inhibited by Si. HRP activity was increased in presence of Si except for 6 mM Si. This may indicate that the complex formed with Si and short oligomers activates the enzyme, and prevents the formation of the large fragments.

Differential Polarization Imaging of Plant Cells. Mapping the Anisotropy of Cell Walls and Chloroplasts.

Modern light microscopy imaging techniques have substantially advanced our knowledge about the ultrastructure of plant cells and their organelles. Laser-scanning microscopy and digital light microscopy imaging techniques, in general-in addition to their high sensitivity, fast data acquisition, and great versatility of 2D-4D image analyses-also opened the technical possibilities to combine microscopy imaging with spectroscopic measurements. In this review, we focus our attention on differential polarization (DP) imaging techniques and on their applications on plant cell walls and chloroplasts, and show how these techniques provided unique and quantitative information on the anisotropic molecular organization of plant cell constituents: (i) We briefly describe how laser-scanning microscopes (LSMs) and the enhanced-resolution Re-scan Confocal Microscope (RCM of Confocal.nl Ltd. Amsterdam, Netherlands) can be equipped with DP attachments-making them capable of measuring different polarization spectroscopy parameters, parallel with the 'conventional' intensity imaging. (ii) We show examples of different faces of the strong anisotropic molecular organization of chloroplast thylakoid membranes. (iii) We illustrate the use of DP imaging of cell walls from a variety of wood samples and demonstrate the use of quantitative analysis. (iv) Finally, we outline the perspectives of further technical developments of micro-spectropolarimetry imaging and its use in plant cell studies.

Photosynthesis Enhancement in Maize via Nontoxic Orange Carbon Dots.

The sustained increase in leaf photosynthesis may increase crop yield. Due to many limitations, plants use much less photosynthetic capacity than is theoretically possible. Plant nanobionics investigates nanoparticle application in living plants, which improves certain plant functions. We synthesized and tested nontoxic orange carbon dots (o-CDs) for the photosynthetic efficiency increase in maize (Zea mays L.). We applied o-CDs foliarly or by adding to the growth solution. The photosynthetic parameters and content of photosynthetic pigments were recorded. The total phenolic content (TPC) and total antioxidant activity (TAA) were measured to monitor the plant antioxidant response to o-CDs. The photosynthetic parameters' values were higher for foliar than for solution application. The 1 mg/L o-CDs applied foliarly and 5 mg/L in solution increased photosynthetic parameters in leaves. The o-CDs raised photosynthetic pigments. The TAA and TPC results indicate reduced antioxidant activity in the plant organs more exposed to o-CDs, depending on the way of application.

Toxicity investigation of CeO2 nanoparticles coated with glucose and exopolysaccharides levan and pullulan on the bacterium Vibrio fischeri and aquatic organisms Daphnia magna and Danio rerio.

Cerium oxide nanoparticles (nCeO2) have widespread applications, but they can be hazardous to the environment. Some reports indicate the toxic effect of nCeO2 on tested animals, but literature data are mainly contradictory. Coating of nCeO2 can improve their suspension stability and change their interaction with the environment, which can consequently decrease their toxic effects. Herein, the exopolysaccharides levan and pullulan, due to their high water solubility, biocompatibility, and ability to form film, were used to coat nCeO2. Additionally, the monosaccharide glucose was used, since it is a common material for nanoparticle coating. This is the first study investigating the impact of carbohydrate-coated nCeO2 in comparison to uncoated nCeO2 using different model organisms. The aim of this study was to test the acute toxicity of carbohydrate-coated nCeO2 on the bacterium Vibrio fischeri NRRL B-11177, the crustacean Daphnia magna, and zebrafish Danio rerio. The second aim was to investigate the effects of nCeO2 on respiration in Daphnia magna which was performed for the first time. Finally, it was important to see the relation between Ce bioaccumulation in Daphnia magna and Danio rerio and other investigated parameters. Our results revealed that the coating decreased the toxicity of nCeO2 on Vibrio fischeri. The coating of nCeO2 did not affect the nanoparticles' accumulation/adsorption or mortality in Daphnia magna or Danio rerio. Monitoring of respiration in Daphnia magna revealed changes in CO2 production after exposure to coated nCeO2, while the crustacean's O2 consumption was not affected by any of the coated nCeO2. In summary, this study revealed that, at 200 mg L-1, uncoated and carbohydrate-coated nCeO2 are not toxic for the tested organisms, however, the CO2 production in Daphnia magna is different when they are treated with coated and uncoated nCeO2. The highest production was in glucose and levan-coated nCeO2 according to their highest suspension stability. Daphnia magna (D. magna), Danio rerio (D. rerio), Vibrio fischeri (V. fischeri).

Estimation of carbon dots amelioration of copper toxicity in maize studied by synchrotron radiation-FTIR.

Carbon dots are biocompatible and non-toxic nanoparticles with chemical affinity to some heavy metals. Human activities increase soil pollution with copper. Cu is an essential microelement in plants, but excess can induce a harmful effects. In plant response to Cu, the cell wall plays an important role. This study aims to estimate possible amelioration effects of folic acid based CDs on Cu toxicity by studying the intracellular and cell wall compounds in maize (Zea mays L.) roots and leaves after 7 day-treatment in hydroponics. The sub-cellular compartmentalization and bio-macromolecular changes induced by 5 µM Cu applied alone or with CDs (167 and 500 mg/L) were studied using the Synchrotron-based Fourier transformmicro-spectroscopy (SR-FTIR) combined with X-Ray photoelectron spectroscopy (XPS). Cu induced changes in content of cell wall polysaccharides, proteins, and lipids. The XPS detected CDs transport throughout the plants. The Cu/167CDs treatment reduced Cu concentration in the roots, possibly by complexation/trapping between the functional groups on CDs surface and Cu2+. Principal component analysis of FTIR spectra confirmed that Cu/500CDs treatment increased Cu adverse effects in most tissues but alleviated adverse Cu effects on cell wall polysaccharides in the root xylem, and on polysaccharides and proteins in leaf phloem and mesophyll.

Screening of semi-volatile compounds in plants treated with coated cerium oxide nanoparticles by comprehensive two-dimensional gas chromatography.

Literature data about semi-volatile organic compounds in plants and the effect of cerium oxide nanoparticles on them are scarce. Surface modification of nanoparticles may change nanoparticle-environment interaction, and therefore affects compounds in plants. In this research, uncoated and glucose-, levan-, and pullulan-coated cerium oxide nanoparticles were used for wheat and pea treatment during the growth. The aim was the screening of semi-volatile organic compounds from plants' shoots using comprehensive two-dimensional gas chromatography-mass spectrometry, a powerful separation technique allowing to reach unique separation resolution, and investigation of qualitative changes after the treatment with coated cerium oxide nanoparticles. The results were analyzed by the identification of individual peaks and fingerprint analysis by image processing. Wheat samples contained a higher number of semi-volatile organic compounds (108) compared to pea (77) but were less affected by the treatments with coated nanoparticles. The highest number of compounds was detected in wheat after the treatment with levan- and pullulan-coated nanoparticles, and in pea after treatment with levan-coated nanoparticles. This article reports a successful application of a semi-volatile organic compounds profile presented only as categorical variables and unique fingerprint images for the inter-cultivar recognition. This method may be useful in screening nanoparticles' effects on different plants.

Cell wall response to UV radiation in needles of Picea omorika.

The UV-B represents the minor fraction of the solar spectrum, while UV-C is not contained in natural solar radiation, but both radiation types can cause damaging effects in plants. Cell walls (CWs) are one of the targets for external stressors. Juvenile P. omorika trees were treated either with 21 day-high doses UV-B or with 7 day- UV-C in open-top chambers. Using spectroscopic and biochemical techniques, it was shown that the response to UV radiation includes numerous modifications in needle CW structure: relative content of xylan, xyloglucan, lignin and cellulose decreased; cellulose crystallinity changed; yield of lignin monomers with stronger connection of CC in side chain with the ring increased; re-distribution of inter- and intra-polymer H-bonds occurred. The recovery was mediated by an increase in the activities and changes in isoform profiles of CW bound covalent peroxidases (POD) and polyphenol oxidases (PO) (UV-B), and ionic POD and covalent PO (UV-C). A connection between activities of specific POD/PO isoforms and phenolic species (m- and p-coumaric acid, pinoresinol and cinnamic acid derivatives) was demonstrated, and supported by changes in the sRNA profile. In vivo fluorometry showed phenolics accumulation in needle epidermal CWs. These results imply transversal connections between polymers and changed mechanical properties of needle CW as a response to UV. The CW alterations enabled maintenance of physiological functions, as indicated by the preserved chlorophyll content and/or organization. The current study provides evidence that in conifers, needle CW response to both UV-B and UV-C includes biochemical modifications and structural remodeling.

Single yeast cell nanomotions correlate with cellular activity.

Living single yeast cells show a specific cellular motion at the nanometer scale with a magnitude that is proportional to the cellular activity of the cell. We characterized this cellular nanomotion pattern of nonattached single yeast cells using classical optical microscopy. The distribution of the cellular displacements over a short time period is distinct from random motion. The range and shape of such nanomotion displacement distributions change substantially according to the metabolic state of the cell. The analysis of the nanomotion frequency pattern demonstrated that single living yeast cells oscillate at relatively low frequencies of around 2 hertz. The simplicity of the technique should open the way to numerous applications among which antifungal susceptibility tests seem the most straightforward.