Identification of drivers of landscape distribution of forest orchids using germination experiment and species distribution models.

The family of orchids involves a number of critically endangered species. Understanding of drivers of their landscape distribution could provide a valuable insight into their decline. Our objectives were to develop models predicting distribution of selected orchid species-four co-occurring forest orchid species, Cephalanthera rubra, Epipactis atrorubens, E. helleborine, and Neottia nidus-avis-at a landscape scale using a wide range of habitat characteristics. Subsequently, we compared the model predictions with species occurrence and the results of the field germination experiment while considering two germination stages-asymbiotic (early stage) and symbiotic. And finally, we attempted to identify possible drivers of species' landscape distribution (i.e., dispersal, availability of habitat patches, or fungal associates). We have discovered that different habitat characteristics determined the distribution of different orchids. The species also differed in terms of availability of suitable habitat patches and patch occupancy (the highest being E. atrorubens with 80%). Landscape distribution of the species was primarily restricted by the availability of fungal associates (the most important factor for C. rubra) and by the availability of suitable habitat patches (the most important in case of N. nidus-avis). Despite expected easy dispersal of spores, orchid distribution seems to be limited by the availability of fungal associates in the landscape. In contrast, the availability of orchid seeds does not seem to limit their distribution. These results can provide useful guidelines for conservation of the studied species.

Tasty rewards for ants: differences in elaiosome and seed metabolite profiles are consistent across species and reflect taxonomic relatedness.

Diaspores of myrmecochorous plants consist of a seed (or fruit) and an attached appendage (elaiosome) which attracts ants. The elaiosome is a food resource for ants, whereas the seed is an energy source for subsequent germination and plant establishment. Although myrmecochory occurs in many phylogenetically unrelated lineages, multiple phylogenetic lineages display similar variation in elaiosome and seed metabolite composition due to convergent evolution. We focused on four families (Amaryllidaceae, Boraginaceae, Papaveraceae and Poaceae) each represented by two species from different genera. Diaspores of three populations per species were sampled and concentrations of 60 metabolites from five groups (amino acids, fatty acids, organic acids, polyols and sugars) were determined for both elaiosomes and seeds. Variability in metabolite composition was decomposed by hierarchical ANOVA and variation partitioning using redundancy analysis (reflecting both species nested within families, crossed with seed vs. elaiosome). Differences in the metabolite composition of elaiosomes and seeds were consistent across multiple phylogenetic origins (with more pronounced differences at the level of individual metabolites than at the level of metabolite groups) and supported the idea of convergent evolution under strong selection pressure. Elaiosomes contained higher amounts of easily digestible metabolites (especially amino acids) than seeds. Fatty acids were not more concentrated in elaiosomes, which contradicts the literal translation of "elaiosome" (= oil body). The differentiation of metabolite composition closely reflected taxonomic relatedness, particularly at the family level. Differences among populations within species were small, so the metabolite composition can thus be considered as a trait with relatively low intraspecific variability.

Liposomal nanotransporter for targeted binding based on nucleic acid anchor system.

Microfluidic techniques have been developed intensively in recent years due to lower reagent consumption, faster analysis, and possibility of the integration of several analytical detectors into one chip. Electrochemical detectors are preferred in microfluidic systems, whereas liposomes can be used for amplification of the electrochemical signals. The aim of this study was to design a nanodevice for targeted anchoring of liposome as transport device. In this study, liposome with encapsulated Zn(II) was prepared. Further, gold nanoparticles were anchored onto the liposome surface allowing binding of thiol moiety-modified molecules (DNA). For targeted capturing of the transport device, DNA loops were used. DNA loops were represented by paramagnetic microparticles with oligo(DT)25 chain, on which a connecting DNA was bound. Capturing of transport device was subsequently done by hybridization to the loop. The individual steps were analyzed by electrochemistry and UV/Vis spectrometry. For detection of Zn(II) encapsulated in liposome, a microfluidic system was used. The study succeeded in demonstrating that liposome is suitable for the transport of Zn(II) and nucleic acids. Such transporter may be used for targeted binding using DNA anchor system.

Remote-controlled robotic platform ORPHEUS as a new tool for detection of bacteria in the environment.

Remote-controlled robotic systems are being used for analysis of various types of analytes in hostile environment including those called extraterrestrial. The aim of our study was to develop a remote-controlled robotic platform (ORPHEUS-HOPE) for bacterial detection. For the platform ORPHEUS-HOPE a 3D printed flow chip was designed and created with a culture chamber with volume 600 µL. The flow rate was optimized to 500 µL/min. The chip was tested primarily for detection of 1-naphthol by differential pulse voltammetry with detection limit (S/N = 3) as 20 nM. Further, the way how to capture bacteria was optimized. To capture bacterial cells (Staphylococcus aureus), maghemite nanoparticles (1 mg/mL) were prepared and modified with collagen, glucose, graphene, gold, hyaluronic acid, and graphene with gold or graphene with glucose (20 mg/mL). The most up to 50% of the bacteria were captured by graphene nanoparticles modified with glucose. The detection limit of the whole assay, which included capturing of bacteria and their detection under remote control operation, was estimated as 30 bacteria per µL.

Behaviour of zinc complexes and zinc sulphide nanoparticles revealed by using screen printed electrodes and spectrometry.

In this study, we focused on microfluidic electrochemical analysis of zinc complexes (Zn(phen)(his)Cl2, Zn(his)Cl2) and ZnS quantum dots (QDs) using printed electrodes. This method was chosen due to the simple (easy to use) instrumentation and variable setting of flows. Reduction signals of zinc under the strictly defined and controlled conditions (pH, temperature, flow rate, accumulation time and applied potential) were studied. We showed that the increasing concentration of the complexes (Zn(phen)(his)Cl2, Zn(his)Cl2) led to a decrease in the electrochemical signal and a significant shift of the potential to more positive values. The most likely explanation of this result is that zinc is strongly bound in the complex and its distribution on the electrode is very limited. Changing the pH from 3.5 to 5.5 resulted in a significant intensification of the Zn(II) reduction signal. The complexes were also characterized by UV/VIS spectrophotometry, chromatography, and ESI-QTOF mass spectrometry.

Evaluation of seed-dispersal services by ants at a temperate pasture: Results of direct observations in an ant suppression experiment.

Ants disperse seeds of many plant species adapted to myrmecochory. While advantages of this ant-plant mutualism for myrmecochorous plants (myrmecochores) have been previously studied in temperate region mostly in forests, our study system was a pasture. Moreover, we used a unique combination of observing the effect of ant-activity suppression on ant dispersal and comparison of the contribution of ant and unassisted dispersal to the distance from mother plant. We established plots without and with ant-activity suppression (enclosures). We offered diaspores of a myrmecochorous (Knautia arvensis), and a non-myrmecochorous (Plantago lanceolata) species in a choice test and followed ants carrying diaspores during days and nights (focus of previous studies was on diurnal dispersal). We measured frequency and distances of ant dispersal and compared them with unassisted dispersal recorded using sticky trap method. The dispersal frequency was lower in enclosures (3.16 times). Ants strongly preferred diaspores of the myrmecochore to non-myrmecochore with 586 and 42 dispersal events, respectively (out of 6400 diaspores of each species offered). Ant dispersal resulted in more even and on average longer distances (maximum almost tenfold longer, 994 cm) in comparison to unassisted dispersal. Ant dispersal altered the distribution of distances of the myrmecochore from roughly symmetric for unassisted dispersal to positively skewed. Ants dispersed heavier diaspores farther. Ants dropped the majority of diaspores during the dispersal (which reduces clustering of seeds), while several (11%) were carried into anthills. Anthills are disturbed microsites presumably favorable for germination in competitive habitats. Ants provided non-negligible dispersal services to myrmecochorous K. arvensis but also, to a lesser extent, of non-myrmecochorous P. lanceolata.

Interaction study of arsenic (III and V) ions with metallothionein gene (MT2A) fragment.

Arsenic compounds belong to the most controversial agents concerning human health. Arsenic (As) is considered as a top environmental element influencing human health due to its adverse effects including cancer, diabetes, cardiovascular disease, and reproductive or developmental problems. Despite the proven mutagenic, teratogenic and carcinogenic effects, the arsenic compounds are used for centuries to treat infectious diseases. In our work, we focused on studying of interactions of As(III) and/or As(V) with DNA. Interactions between arsenic ions and DNA were monitored by UV/vis spectrophotometry by measuring absorption and fluorescence spectra, atomic absorption spectrometry, electrochemical measurements (square wave voltammetry) and agarose gel electrophoresis. Using these methods, we observed a stable structure of DNA with As(III) within the concentration range 0.4-6.25 µg mL(-1). Higher As(III) concentration caused degradation of DNA. However, similar effects were not observed for As(V).

Effect of ampicillin, streptomycin, penicillin and tetracycline on metal resistant and non-resistant Staphylococcus aureus.

There is an arising and concerning issue in the field of bacterial resistance, which is confirmed by the number of deaths associated with drug-resistant bacterial infections. The aim of this study was to compare the effects of antibiotics on Staphylococcus aureus non-resistant strain and strains resistant to cadmium or lead ions. Metal resistant strains were created by the gradual addition of 2 mM solution of metal ions (cadmium or lead) to the S. aureus culture. An increasing antimicrobial effect of ampicillin, streptomycin, penicillin and tetracycline (0, 10, 25, 50, 75, 150, 225 and 300 µM) on the resistant strains was observed using a method of growth curves. A significant growth inhibition (compared to control) of cadmium resistant cells was observed in the presence of all the four different antibiotics. On the other hand, the addition of streptomycin and ampicillin did not inhibit the growth of lead resistant strain. Other antibiotics were still toxic to the bacterial cells. Significant differences in the morphology of cell walls were indicated by changes in the cell shape. Our data show that the presence of metal ions in the urban environment may contribute to the development of bacterial strain resistance to other substances including antibiotics, which would have an impact on public health.

Lead ions encapsulated in liposomes and their effect on Staphylococcus aureus.

The aim of the study was the preparation of a liposome complex with encapsulated lead ions, which were electrochemically detected. In particular, experiments were focused on the potential of using an electrochemical method for the determination of free and liposome-encapsulated lead and determination of the encapsulation efficiency preventing the lead toxicity. Primarily, encapsulation of lead ions in liposomes and confirmation of successful encapsulation by electrochemical methods was done. Further, the reduction effect of the liposome matrix on the detected electrochemical signal was monitored. Besides encapsulation itself, comparison of toxicity of free lead ions and lead ions encapsulated in liposome was tested. The calculated IC50 values for evaluating the lead cytotoxicity showed significant differences between the lead enclosed in liposomes (28 µM) and free lead ions (237 µM). From the cytotoxicity studies on the bacterial strain of S. aureus it was observed that the free lead ions are less toxic in comparison with lead encapsulated in liposomes. Liposomes appear to be a suitable carrier of various substances through the inner cavity. Due to the liposome structure the lead enclosed in the liposome is more easily accepted into the cell structure and the toxicity of the enclosed lead is higher in comparison to free lead ions.

Electrochemical modification of a graphite platform for a solid sampling electrothermal atomic absorption spectrometry of mercury.

An electrodeposited palladium and iridium/gold mixture has been investigated as a chemical modifier for mercury determination in environmental samples by solid sampling electrothermal atomic absorption spectrometry. Electrochemical procedures of platform surface modification performed in a cell with 20 ml of solution, and in a drop of modifier solution have been optimized. Simple electrolysis in a drop was found to be the most consistent, taking the reproducibility as the major criterion. A total mass of 250 µg of electrodeposited palladium or an iridium/gold mixture was used. The lifetime of 60 - 70 firings for a deposited iridium/gold mixture was smaller than that for palladium with a lifetime of 100 - 120 firings. The detection limit was 120 pg Hg. Different sample masses of between 0.1 and 10 mg were weighed into modified platforms according to the mercury content. The results obtained for mercury in environmental samples as soils, sediments and plant, using solid sampling and calibration against aqueous standards stabilized by potassium permanganate, were in good agreement with those achieved by using the thermal deposition of modifiers and with measurements by pyrolysis atomic absorption spectrometry with gold amalgamation.