Effect of Graphene Oxide and Ammonia-modified Graphene Oxide Particles on ATPase Activity of Rat Liver Mitochondria

Graphene and its derivatives have become promising materials for biomedical applications in the last decade. Before their widespread application, however, evaluating their toxicity and mechanisms underlying interactions with cellular components is imperative. Aims: Assessment of the effect of two graphene derivatives, pristine graphene oxide (GO) and ammonia-modified GO (GO-NH2) particles, on the ATPase activity of rat liver mitochondria and ROS production. Methods: Liver mitochondria were isolated from male albino rats and treated with different concentrations of GO and GO-NH2 particles (4, 10, 25, and 50 μg/ml). ATPase activity of both, intact and uncoupled by freezing/thawing mitochondria was determined by the measurement of inorganic phosphate (Pi) released from ATP. The generation of hydrogen peroxide (H2O2) after exposure of mitochondria to GO and GO-NH2 particles was determined by a DCFH-D assay. Results: GO and GO-NH2 particles applied at concentrations of 4 and 50 μg/ml did not affect the ATPase activity of intact mitochondria. In contrast, in uncoupled mitochondria, they demonstrated a stimulating effect on ATPase activity. The impact of GO-NH2 was more substantial and concentration-dependent. ROS production was also higher in GO-NH2-treated mitochondria. Conclusion: The present study demonstrated that GO and GO-NH2 particles can exert a cytotoxic effect on mitochondria even after a short-time of exposure to both types of particles.

INFLUENCE OF THE LONG-TERM PRESERVATION ON SOME BIOLOGICAL FEATURES OF THREE STREPTOMYCETES STRAINS, PRODUCERS OF ANTIBIOTIC SUBSTANCES

The influence of long-term preservation in lyophilized state on the survival, the morphology and antibiotic activity of three streptomycetes strains Streptomyces galbus (F) subsp. achromogenes 695, Str. albogriseolus 444 and Streptomyces sp. T-741 was studied. It was established that viability of the strains depended not only on the conditions of lyophilization but also on the physiological state and strain features of the cultures. The spores of the strain 695, 444 and T-741 remained viable 13, 21 and 8 years respectively. At the same time an increase of the polymorphism of the strains 695 and 444 and appearance of new morphological types was observed. The method of lyophilization was suitable also for long-term storage of antibiotic activity of the three strains. The activity was retained to 80-90% from initial one

INFLUENCE OF THE LONG-TERM PRESERVATION ON SOME BIOLOGICAL FEATURES OF THREE STREPTOMYCETES STRAINS, PRODUCERS OF ANTIBIOTIC SUBSTANCES

The influence of long-term preservation in lyophilized state on the survival, the morphology and antibiotic activity of three streptomycetes strains Streptomyces galbus (F) subsp. achromogenes 695, Str. albogriseolus 444 and Streptomyces sp. T-741 was studied. It was established that viability of the strains depended not only on the conditions of lyophilization but also on the physiological state and strain features of the cultures. The spores of the strain 695, 444 and T-741 remained viable 13, 21 and 8 years respectively. At the same time an increase of the polymorphism of the strains 695 and 444 and appearance of new morphological types was observed. The method of lyophilization was suitable also for long-term storage of antibiotic activity of the three strains. The activity was retained to 80-90% from initial one

New Data on Cylindrospermopsin Toxicity

Cylindrospermopsin (CYN) is a widely spread cyanotoxin that can occur in fresh water and food. This research aims to investigate CYN toxicity by studying the effects of drinking 0.25 nM of CYN-contaminated water from a natural source, and of the direct application of moderate concentrations of CYN on different animal targets. The chosen structures and activities are rat mitochondria inner membrane permeability, mitochondrial ATP synthase (ATPase) and rat liver diamine oxidase (DAO) activities (EC 1.4.3.22.), the force of the contraction of an excised frog heart preparation with functional innervation, and the viability of a human intestinal epithelial cell line (HIEC-6). The oral exposure to CYN decreased the reverse (hydrolase) activity of rat liver ATPase whereas its short-term, in vitro application was without significant effect on this organelle, DAO activity, heart contractions, and their neuronal regulation. The application of CYN reduced HIEC-6 cells’ viability dose dependently. It was concluded that CYN is moderately toxic for the human intestinal epithelial cells, where the regeneration of the epithelial layer can be suppressed by CYN. This result suggests that CYN may provoke pathological changes in the human gastrointestinal tract