The role of natural biopolymers in genotoxicity of mutagens/carcinogens elimination

Nowadays naturally occurring compounds with the potential antimutagenic and anticarcinogenic effects are of great importance for their prospective use in cancer chemoprevention and treatment. The new water soluble derivative of microbial polysaccharide beta-D-glucan-carboxymethyl glucan (CMG) belongs to such a category of natural substances. CMG isolated from the cell wall of baker's yeast Saccharomyces cerevisiae is included into the class of biopolymers known as biological response modifiers (BRMs) with a broad range of activities, above all ones interfering with cancer therapy. It was demonstrated on four experimental model systems that biological and consequential medicinal importance of CMG is based on the combined application with another active compound. In the Saccharomyces cerevisiae antimutagenicity assay CMG significantly reduced ofloxacin-induced mutagenicity in the yeast strain D7. CMG exerted bioprotective (anti-toxic and antimutagenic) effect after its simultaneos application with methyl methanesulphonate on the repair-deficient strain uvs10 of the unicellular green alga Chlamydomonas reinhardtii. In the Vicia sativa simultaneous phytotoxicity and anticlastogenicity assay CMG exerted statistically significant anticlastogenic efect against maleic hydrazide-induced clastogenicity in Vicia sativa L. Only in the Salmonella/microsome assay CMG did not exert statistically significant antigenotoxic effect, despite of the fact that it reduced 9-aminoacridine-induced mutagenicity in S. typhimurium TA97, but his(+) revertants decreasing was statistically significant only at the highest CMG concentration used. The data presented unambiguously documented that even biopolysaccharides (e.g., derivatives of beta-glucan) belonging to the most abundant class of natural biopolymers may contribute to cancer prevention and therapy.     

Circumscription of species in the <Emphasis Type="Italic">Hodophilus foetens</Emphasis> complex (Clavariaceae,Agaricales) in Europe

Four European Hodophilus species with an odour similar to naphthalene, a strong unpleasant odour similar to that of mothballs, are recognized based on sequence and/or morphological data. The traditional concept defines Ho. foetens as the only Hodophilus species with a naphthalene odour in Europe. This name is now assigned to one of the studied species based on morphological examination of the holotype specimen. A recently collected specimen is proposed as the epitype. The other three species with a naphthalene odour are described here as new: Ho. pallidus, Ho. subfoetens and Ho. tenuicystidiatus. They are distinguishable in the field based on a combination of lamellae number and colour of basidiomata. All four species are grouped in the Ho. foetens superclade, one of two superclades, together with the Ho. micaceus superclade, in the genus Hodophilus. All are different species from North American taxa with a naphthalene-like odour recognised in a previous study. The Ho. foetens superclade also includes one species identified as Ho. atropunctus that does not have a distinctive odour. The type collection of Ho. albofloccipes, a recently described European species with a naphthalene odour, is placed together with some collections without a distinctive odour in the Ho. micaceus superclade.     

NMR structural study of fructans produced by Bacillus sp. 3B6, bacterium isolated in cloud water

Bacillus sp. 3B6, bacterium isolated from cloud water, was incubated on sucrose for exopolysaccharide production. Dialysis of the obtained mixture (MWCO 500) afforded dialyzate (DIM) and retentate (RIM). Both were separated by size exclusion chromatography. RIM afforded eight fractions: levan exopolysaccharide (EPS), fructooligosaccharides (FOSs) of levan and inulin types with different degrees of polymerization (dp 2–7) and monosaccharides fructose:glucose = 9:1. Levan was composed of two components with molecular mass ∼3500 and ∼100 kDa in the ratio 2.3:1. Disaccharide fraction contained difructose anhydride DFA IV. 1-Kestose, 6-kestose, and neokestose were identified as trisaccharides in the ratio 2:1:3. Fractions with dp 4–7 were mixtures of FOSs of levan (2,6-βFruf) and inulin (1,2-βFruf) type. DIM separation afforded two dominant fractions: monosaccharides with fructose: glucose ratio 1:3; disaccharide fraction contained sucrose only. DIM trisaccharide fraction contained 1-kestose, 6-kestose, and neokestose in the ratio1.5:1:2, penta and hexasaccharide fractions contained FOSs of levan type (2,6-βFruf) containing α-glucose. In the pentasaccharide fraction also the presence of a homopentasaccharide composed of 2,6-linked βFruf units only was identified. Nystose, inulin (1,2-βFruf) type, was identified as DIM tetrasaccharide. Identification of levan 2,6-βFruf and inulin 1,2-βFruf type oligosaccharides in the incubation medium suggests both levansucrase and inulosucrase enzymes activity in Bacillus sp. 3B6.     

The circular dichroism and differential scanning calorimetry study of the properties of DNA aptamer dimers

We have applied circular dichroism (CD), temperature-gradient gel electrophoresis (TGGE) and differential scanning calorimetry (DSC) to study the properties of novel bioengineered DNA aptamer dimers sensitive to fibrinogen (F) and heparin (H) binding sites of thrombin and compared them with canonical single stranded aptamer sensitive to fibrinogen binding site of thrombin (Fibri). The homodimer (FF) and heterodimer (FH) aptamers were constructed based on hybridization of their supported parts. CD results showed that both FF and FH dimers form stable guanine quadruplexes in the presence of potassium ions like those in Fibri. The thermal stability of aptamer dimers was slightly lower compared to those of canonical aptamers, but sufficient for practical applications. Both FF and FH aptamer dimers exhibited a potassium-dependent inhibitory effect on thrombin-mediated fibrin gel formation, which was on average two-fold higher than those of canonical single stranded Fibri aptamers.     

Hay-bait traps are a useful tool for sampling of soil dwelling millipedes and centipedes

Some species of centipedes and millipedes inhabit upper soil layers exclusively and are not recorded by pitfall trapping. Because of their sensitivity to soil conditions, they can be sampled quantitatively for evaluation of soil conditions. Soil samples are heavy to transport and their processing is time consuming, and such sampling leads to disturbance of the soil surface which land-owners do not like. We evaluated the use of hay-bait traps to sample soil dwelling millipedes and centipedes. The effectiveness of this method was found to be similar to the effectiveness of soil sampling. Hay-bait traps installed for 8–10 weeks can substitute for direct soil sampling in ecological and inventory studies.     

Determination of the cross-linking effect of adipic acid dihydrazide on glycoconjugate preparation

The cross-linking effect of adipic acid dihydrazide (ADH) on polysaccharide derivatization can be evaluated by applying combination of elemental analysis and colorimetric assay. Elemental analysis is used for estimation of total ADH bound to polysaccharide and a colorimetric trinitrobenzene sulfonic acid assay is used to determine the part of ADH not involved in cross-linking. The difference of values expressed as molar ratios (per repeating unit) provides information on the amount of ADH involved in cross-linking the polysaccharides. Carboxymethylated polysaccharides were derivatized with different amounts of ADH to test the procedure. Analytical results showed that excess of ADH in the reaction only slightly decreased the cross-linking. The number of carboxyl groups remained unmodified even at high excess of ADH and high concentration of carbodiimide (EDC) coupling reagent.     

The Langhian (Middle Badenian) carbonate production event in the Moravian part of the Carpathian Foredeep (Central Paratethys): a multiproxy record

The carbonate production event in the Moravian part of the Carpathian Foredeep is known as a deposition of a carbonate–siliciclastic complex in the marginal part of the basin, correlating with the time period from the last occurrence of Helicosphaera waltrans (14.36 Ma) to the last occurrence of Sphenolithus heteromorphus (13.34 Ma). Sedimentological and microfacial data, analysis of foraminifera, calcareous nannoplankton, red algae, mollusks, palynology, as well as oxygen and carbon stable isotopes from foraminiferal tests, were used to interpret the specific paleoenvironment of the carbonate production event. The event was accelerated by a decrease of terrigenous input due to a large transgression and, primarily, an increasingly arid climate. Production of carbonate was related to oligotrophic conditions, expansion of sea-grass meadows, summer downwelling circulations and winter stratification of the water column. Autochthonous and semi-autochthonous carbonates were deposited in shallow-water near the fair-weather wave-base; allochthonous carbonates were transported to the outer shelf by gravity flows. Climatic instability and relative sea-level changes, induced mainly by substantial tectonic activity, caused the carbonate bodies to be small with a high ratio of siliciclastic components, indicating only a short-term and spatially restricted environment suitable for carbonate production. Exceptionally, carbonate production persisted longer during the whole sea-level cycle (“Rousínov Ridge”). Siliciclastic intercalations in these larger limestone bodies represent catastrophic rain events that transported a higher amount of terrigenous material into the basin. The specific climatic conditions of the carbonate production event, namely climatic instability and aridification with episodic intensive rain, were associated with the Middle Miocene climatic transition in the study area.     

The adaptation responses of bacterial cytoplasmic membrane fluidity in the presence of environmental stress factors — polychlorinated biphenyls and 3-chlorobenzoic acid

Only bacteria sufficiently resistant to the toxic compounds in their environment can be used for the efficient biodegradation process in order to eliminate a widespread contamination by polychlorinated biphenyls (PCBs). The presence of PCBs results in bacterial controlled rigidification of cytoplasmic membrane. The four bacterial isolates from long-term PCB-contaminated soil (Alcaligenes xylosoxidans, Pseudomonas stutzeri) and sediment (Ochrobactrum anthropi, Pseudomonas veronii) have been used to select the strain most adapted to the PCBs, i.e. with efficient changes in the membrane phospholipid fatty acids. PCBs and their toxic degradation products — the 3-chlorobenzoic acids (3-CBA as the most toxic one) — were added separately to the liquid medium with glucose in two experimental sets: at lag phase and in stationary phase of bacterial growth in order to evaluate the effects of chemicals to cytoplasmic membrane. The main parameter — the changes in fatty acids composition (in the total lipids and the main membrane phospholipid phosphatidyletanolamine) were studied. 3-CBA caused growth inhibition when added at lag phase. However, when added during the stationary growth, inhibition was not observed. Similarly, after addition of PCBs to the stationary growth culture, inhibition of growth was not observed with all tested strains (except for P. stutzeri). This fact indicates the importance of time contact of bacteria during growth phase with xenobiotics. O. anthropi and A. xylosoxidans appeared to be the most adapted to the presence of PCBs (with sufficient membrane adaptation), active under the adverse conditions, and able to survive in the contaminated environment.