Vol 53, No 3 (2017)

Methylglyoxal (MG) is one of the physiological glucose metabolites formed in living organisms. The data on the influence of MG on different internal systems of eukaryotic cells, including the central signaling pathways, are been discussed in the review. The central signaling pathways are stress-activated and sensitive to the action of reactive oxygen species. Integration of the literary data and authors’ results has allowed the conclusion that MG action on cells is multidirectional and is determined by its concentration and the physiological state of the cell. The cellular reaction upon increasing MG concentrations has a phase pattern and can be described by the hormesis concept. It has been hypothesized that MG participates in the formation of the braking regulatory circuit, which modulates the sensitivity of hypothalamus neurons to glucose. It is concluded that MG has a possible role in the functioning of the great biological clock. We propose that the data discussed in this review allow methylglyoxal to be considered a molecule with signal and regulatory functions.

This study describes the impact of 5′-end codon modulation on the expression of a heterologous gene, human granulocyte colony stimulating factor (GCSF), in Escherichia coli. Fourteen different constructs (pGCSF-01 to pGCSF-14) carrying single or multiple synonymous substitutions at +2, +3 and further down from +4 to +7 codons, were prepared and their expression was monitored in E. coli BL21 Codon-Plus (DE3) RIPL using a strong T7 lac-promoter based expression system. A single nucleotide change at +2 Thr codon (ACC→ACA) either alone or in combination with +3 Pro codon (CCC/CCT/CCA) resulted in the expression enhancement of an otherwise poorly expressed native-GCSF, to a level that corresponded to 45–50% of the total E. coli BL21 CodonPlus (DE3) RIPL cellular proteins. The differences in GCSF expression amongst different constructs could be attributed to the preferential or non-preferential codon usage, reduced number of G/C nucleotides and the stability of mRNA secondary structure formed near the 5′-end coding region. The expression of GCSF achieved was in the form of biologically inactive inclusion bodies that were solubilized using mild concentration of a non-ionic surfactant and refolded by a simplified, step-dialysis approach. Biological activity of the purified GCSF, assessed in induced neutropenic mice, was similar to the commercially available preparation of the GCSF analog (filgrastim).

DNA isolated from a greenhouse soil (Nanjing, Jiangsu Province, China) was suitable for PCR amplification of gene segment coding for the 16S rRNA. Diverse PCR products were characterized by cloning and sequencing, and analysis of bacterial colonies showed the presence over 26 phyla. The most bacteria belonged to Proteobacteria, Actinobacteria, Gemmatimonadetes, Acidobacteria and Planctomycetes. Furthermore, after the enrichment procedure of DBP-degrading microorganisms, 4 strains were isolated from the soil sample with di-n-butyl phthalate (DBP) biodegradability, and they were identified to be Rhizobium sp., Streptomyces sp., Pseudomonas sp. and Acinetobacter sp. Analysis of the degradation products by LC-MS led to identification of metabolites of DBP in strain LMB-1 (identified as Rhizobium sp.) which suggests that DBP was degraded through β-oxidation, demethylation, de-esterification and cleavage of aromatic ring.

Two new bacterial biopolymers (exopolysaccharides), ancylan and xylophilan, have been isolated and characterized. The optimal parameters for ancylan and xylophilan production under laboratory conditions were selected. Their physicochemical properties and effects on microorganisms (bacteria, fungi, and ciliates) were studied. The results suggest the potential application of these new exopolysaccharides in medicine and veterinary science.

A strain of Serratia sp. Ent16 isolated from internal tissues of pea nodule inhibited in vitro growth of the plant pathogens Fusarium oxysporum and Bipolaris sorokiniana and the model strain Rhizobium leguminosarum bv viceae 1078 but had a considerably weaker antagonistic effect on the Rhizobium strain Rh16 from its own nodule. Cells of the Ent16 strain tagged by the gfp gene (the Ent16-gfp strain) were not seen in the pea endorhizosphere when plants were grown in a rich culture medium. The development of symbiosis was favored by plant germination on filter paper. Confocal microscopy showed that individual cells of the Ent16-gfp strain were attached to the outer side of root hair cell walls, while agglomerations of fluorescent bacterial cells were detected in the zone of exoderm of lateral root formation and in root vessels. A series of scanned sections of pea root revealed the presence of the Ent16-gfp strain in lateral root primordia, through which the bacteria penetrated the endorhizosphere.

The effect of malonate and sedaxane, a compound with the fungicidal effect which act as succinate dehydrogenase inhibitors, on the resistance of etiolated wheat seedlings (Triticum aestivum L.) to osmotic stress caused by 12% PEG 6000 solution, was studied. The presowing treatment of seeds with 0.3 mM sedaxane solution significantly reduced the inhibitory effect of osmotic stress on seedling growth. The protective effect of 10 mM malonate was significant when it was added to the incubation medium of the roots; the effect of preseeding treatment with malonate was less significant. Unlike malonate, malate had no positive effect on seedling growth under osmotic stress. The activity of succinate dehydrogenase and the hydrogen peroxide content decreased in seedlings after the treatment of roots with malonate and sedaxane. Pretreatment with sedaxane and the addition of malonate to the incubation medium of roots prevented the accumulation of a lipid peroxidation product, malondialdehyde, which is caused by osmotic stress, and increased peroxidase activity. It was concluded that the stress-protective effect of sedaxane and malonate on wheat seedlings might be due to the inhibition of succinate dehydrogenase-dependent formation of reactive oxygen species and the prevention of oxidative cell damage.

The aim of this study was to investigate the effect of synthetic detergent Merix (Henkel, Kruševac, Serbia), and its particular components—ethoxylated oleyl-cetyl alcohol and sodium tripolyphosphate on the growth and metabolic activity of Penicillium verrucosum. During 19 days of fungal cultivation in Czapek-Dox liquid medium supplemented with or without 0.5% pollutants, the following parameters were observed: pH, the total biomass dry weight, the quantity of free and total organic acids and proteolytic activity. The detergent caused a slight stimulatory (2.41%) effect whereas sodium tripolyphosphate and ethoxylated oleyl-cetyl alcohol provided a slight inhibitory action (0.59 and 2.75%, respectively) on the fungal biomass. The pollutants decreased pH values of the media and the quantity of free organic acids. In contrast, they enhanced the quantity of total organic acids. Proteolytic activity remained nearly unchanged (95.8%) in the presence of detergent and reduced to 80.1% in sodium tripolyphosphate-supplemented medium. In contrast, the enzyme activity sharply increased (260.8%) with ethoxylated oleyl-cetyl alcohol. The obtained results indicate the potential of P. verrucosum in bioremediation of environment contaminated with synthetic detergent taken in high concentration.

The mediators ferrocene, 1,1'-dimethylferrocene, ferrocene carboxaldehyde, ferrocene acetonitrile, neutral red, 2,6-dichlorophenolindophenol, thionine, methyl blue, and potassium ferricyanide were used in combination with Debaryomyces hansenii yeast cells to create a biosensor receptor for biochemical oxygen demand (BOD) assays. In this eukaryote, ferrocene and neutral red were observed to efficiently transfer electrons. The biosensor based on ferrocene was characterized by long-term stability (39 days) and a wide range of substrate specificity. The lower detected concentration boundary was 25.2 mg O₂/dm³. A high correlation (R = 0.9971) was observed between the results obtained with water samples by this approach and the standard method. This is the first attempt to create a combination of yeast cells and a mediator. The biosensor can be employed for further research on the possibilities of its conventional use.