Changes of photosynthesis and carbon metabolism in Typha angustifolia L grown in conditions of nitrate nitrogen overload

Nitrates may induce alterations in NO-signaling system and change photosynthesisin plants. Significant reduction of 14CO2 fixation was noted at concentration of 3.96mM NaNO3 in an aquatic macrophyte (Typha angustifolia L.). Assimilation of 14CO2 seven days after the introduction of nitrates did not differ between control and experimental samples. There were changes in distribution of 14C among products of 4CO2 fixation 4 h after NaNO3 addition, resulting in increased sugar radioactivity in experimental plants. It was suggested that the observed changes may have regulatory importance

Effect of silencing of the apoplastic invertase gene on photosynthesis in tomato

© 2015 Pleiades Publishing, Ltd. Photosynthesis was examined in wild-type tomato plants (Lycopersicon esculentum L., cv. Money-maker) and in the transformants where gene expression of the leaf apoplastic invertase was suppressed by RNA interference (Lin8-RNAi). The influence of genetic transformation on photosynthesis depended on the demand for assimilates by sink organs. Using growth pots with low amount of soil, we found that at the initial growth stage when growth processes were particularly active, photosynthesis in Lin8-RNAi plants was higher than in the wild-type plants. As the reserves of mineral nutrients were gradually exhausted, photosynthesis decreased in both plant groups, but the decrease was more extensive in Lin8-RNAi plant form. Analysis of the distribution of 14C among the photosynthates produced after 3-min period of 14CO2 assimilation revealed the decreased incorporation of 14C into hexoses in Lin8-RNAi plants and the increased incorporation of 14C into aspartate and products of the glycolate pathway. Supplementing the soil with nitrate nitrogen as a fertilizer enhanced the non-carbohydrate trend of photosynthesis, but this trend was less pronounced in the transformed plants. Simultaneous measurements of CO2-exchange and H2O release revealed an insignificant increase in Lin8-RNAi plants of photosynthetic activity, transpiration, and intraleaf CO2 concentration. However, in 30–50 min after lowering the photon flux density from 1556 to 771 μmol/(m2 s) photosynthesis was reduced in both genotypes, whereas transpiration was diminished in wild-type plants and increased in the Lin8-RNAi form. It is concluded that the apoplastic invertase regulates photosynthesis through changes in osmolarity of the apoplastic fluid that controls the opening of stomata

Uptake of halloysite clay nanotubes by human cells: Colourimetric viability tests and microscopy study

© 2018 This study is a systemic investigation of the uptake and toxicity of halloysite nanotubes using human adenocarcinoma epithelial cells (A549). A549 cells were chosen as a popular model of cancer cells extensively studied in nanotoxicity and drug delivery research. The adverse effects of a range of halloysite concentrations were evaluated. The viability of A549 cells was determined using several colourimetric assays. Dark-field microscopy was used to visualize the uptake and distribution of halloysite nanotubes in cells. The morphology of the cells was evaluated using dark-field, transmission electron and atomic force microscopies. The results showed that halloysite had a dose-dependent effect on human cells at concentrations of 5–900 μg per 105 cells in the MTT assay. The reduced toxicity of halloysite nanotubes at lower concentrations (5–75 μg per 105 cells) was additionally supported by the results of other colorimetric assays. Microscopy assays have demonstrated that the nanotubes, though affecting the biochemical processes, do not alter the morphology of the cells and do not penetrate into the nuclei

Synthesis and Testing of Abscisic Acid with Predominant Replacement of Protium Atoms by Tritium in the Cyclohexene Moiety

© 2018, Pleiades Publishing, Inc. Abstract: A procedure for tritiation of predominantly the cyclohexene moiety of abscisic acid was developed. Tritium was introduced by isotope exchange reaction with 100% tritiated water at 220°C in the presence of diisopropylethylamine. The yield of abscisic acid was 50%, and the specific activity was 30.5 Ci/mmol. The labeled product was tested. It was shown that tritiated abscisic acid synthesized by the proposed method did not differ from the unlabeled precursor and could be used for biological assays

Sequence does not matter: The biomedical applications of dna-based coatings and cores

Biomedical applications of DNA are diverse but are usually associated with specific recognition of target nucleotide sequences or proteins and with gene delivery for therapeutic or biotechnological purposes. However, other aspects of DNA functionalities, like its nontoxicity, biodegradability, polyelectrolyte nature, stability, thermo-responsivity and charge transfer ability that are rather independent of its sequence, have recently become highly appreciated in material science and biomedicine. Whereas the latest achievements in structural DNA nanotechnology associated with DNA sequence recognition and Watson–Crick base pairing between complementary nucleotides are regularly reviewed, the recent uses of DNA as a raw material in biomedicine have not been summarized. This review paper describes the main biomedical applications of DNA that do not involve any synthesis or extraction of oligo-or polynucleotides with specified sequences. These sequence-independent applications currently include some types of drug delivery systems, biocompatible coatings, fire retardant and antimicrobial coatings and biosensors. The reinforcement of DNA properties by DNA complexation with nanoparticles is also described as a field of further research

Probing antimicrobial halloysite/biopolymer composites with electron microscopy: Advantages and limitations

Halloysite is a tubular clay nanomaterial of the kaolin group with a characteristic feature of oppositely charged outer and inner surfaces, allowing its selective spatial modification. The natural origin and specific properties of halloysite make it a potent material for inclusion in biopolymer composites with polysaccharides, nucleic acids and proteins. The applications of halloysite/biopolymer composites range from drug delivery and tissue engineering to food packaging and the creation of stable enzyme-based catalysts. Another important application field for the halloysite complexes with biopolymers is surface coatings resistant to formation of microbial biofilms (elaborated communities of various microorganisms attached to biotic or abiotic surfaces and embedded in an extracellular polymeric matrix). Within biofilms, the microorganisms are protected from the action of antibiotics, engendering the problem of hard-to-treat recurrent infectious diseases. The clay/biopolymer composites can be characterized by a number of methods, including dynamic light scattering, thermo gravimetric analysis, Fourier-transform infrared spectroscopy as well as a range of microscopic techniques. However, most of the above methods provide general information about a bulk sample. In contrast, the combination of electron microscopy with energy-dispersive X-ray spectroscopy allows assessment of the appearance and composition of biopolymeric coatings on individual nanotubes or the distribution of the nanotubes in biopolymeric matrices. In this review, recent contributions of electron microscopy to the studies of halloysite/biopolymer composites are reviewed along with the challenges and perspectives in the field

Multicellular spheroids formation: The synergistic effects of halloysite nanoclay and cationic magnetic nanoparticles

© 2018 Elsevier B.V. We investigated the influence of halloysite nanotubes and magnetic nanoparticles stabilized by positively charged polyelectrolyte polyallyamine hydrochloride (PAH) on the built-up of multicellular spheroids using cancer and primary cell cultures. We found no adverse effects caused by the nanoparticles investigated on the formation of 3D cell structures. The use of magnetic nanoparticles (MNPs) has allowed controlling the spheroid spatial movement, which may find applications in cell biology, tissue engineering and nanomedicine. We have also shown for the first time that halloysite nanotubes do not affect the formation of spheroids, including those formed from mesenchymal stem cells

Uptake of halloysite clay nanotubes by human cells: Colourimetric viability tests and microscopy study

© 2018 This study is a systemic investigation of the uptake and toxicity of halloysite nanotubes using human adenocarcinoma epithelial cells (A549). A549 cells were chosen as a popular model of cancer cells extensively studied in nanotoxicity and drug delivery research. The adverse effects of a range of halloysite concentrations were evaluated. The viability of A549 cells was determined using several colourimetric assays. Dark-field microscopy was used to visualize the uptake and distribution of halloysite nanotubes in cells. The morphology of the cells was evaluated using dark-field, transmission electron and atomic force microscopies. The results showed that halloysite had a dose-dependent effect on human cells at concentrations of 5–900 μg per 105 cells in the MTT assay. The reduced toxicity of halloysite nanotubes at lower concentrations (5–75 μg per 105 cells) was additionally supported by the results of other colorimetric assays. Microscopy assays have demonstrated that the nanotubes, though affecting the biochemical processes, do not alter the morphology of the cells and do not penetrate into the nuclei

Recent advances in the design of inorganic and nano-clay particles for the treatment of brain disorders

Inorganic materials, in particular nanoclays and silica nanoparticles, have attracted enormous attention due to their versatile and tuneable properties, making them ideal candidates for a wide range of biomedical applications, such as drug delivery. This review aims at overviewing recent developments of inorganic nanoparticles (like porous or mesoporous silica particles) and different nano-clay materials (like montmorillonite, laponites or halloysite nanotubes) employed for overcoming the blood brain barrier (BBB) in the treatment and therapy of major brain diseases such as Alzheimer's, Parkinson's, glioma or amyotrophic lateral sclerosis. Recent strategies of crossing the BBB through invasive and not invasive administration routes by using different types of nanoparticles compared to nano-clays and inorganic particles are overviewed

Nanoarchitectonics meets cell surface engineering: Shape recognition of human cells by halloysite-doped silica cell imprints

© 2019 Rozhina et al. Cell surface engineering, as a practical manifestation of nanoarchitectonics, is a powerful tool to modify and enhance properties of live cells. In turn, cells may serve as sacrificial templates to fabricate cell-mimicking materials. Herein we report a facile method to produce cell-recognising silica imprints capable of the selective detection of human cells. We used HeLa cells to template silica inorganic shells doped with halloysite clay nanotubes. The shells were destroyed by sonication resulting in the formation of polydisperse hybrid imprints that were used to recognise HeLa cells in liquid media supplemented with yeast. We believe that methodology reported here will find applications in biomedical and clinical research