The effect of genotype on a barley scutella culture. Histological aspects

Cereals are known to be recalcitrant to the induction of morphogenesis in vitro and the majority of the methods used are callus-mediated and species/genotype-dependent. In the present investigation, a method of morphogenesis induction from immature scutella of selected barley cultivars was used, and particular attention was paid to histology in the initial stages of the regeneration process in order to confirm whether it occurs directly or indirectly (via callus formation). The length of the period from inoculating scutella on the medium to obtaining plantlets depended on the cultivar and the individual scutellum of the barley and varied between 2.5–4 months. The regeneration efficiency and viability of barley scutella was revealed to be highly genotype dependent. The average number of regenerated plants per regenerating scutellum was highest in the case of cv Granal (3.7). A histological analysis of the cultured explants showed both non-morphogenic and morphogenic callus formation. Two types of indirect morphogenetic response were observed: organogenesis (shoot bud formation) and somatic embryogenesis. This is the first report concerning an analysis of in vitro regeneration from immature scutella of barley cultivars (Stratus, Ryton, Granal and Binal).     

Investigations on purine and pyrimidine bases stacking associations in aqueous solutions by the fluorescence quenching method: II. Heteroassociation between 2-aminopurine and thymidine

Heteroassociation between A and B compounds in liquid solution was considered. Provided that concentration of A molecules is low, a geneial equation describing fluorescence quantum yield and lifetime of compound A as a function of B molecules concentration was derived. The heteroassociation between 2-aminopurine and thymidine in aqueous solutions was examined within the range of temperatures 0 to 90° C. The equilibrium constants of the first step of association, namely heterodimer formation, were determined and its thermodynamic parameters (ΔH = ?2.76 $\text{kcal}\text{mol}$, ΔS = ?5.9 e.u.) were calculated. The observed changes of the stacking rate constants with temperature confirm the two-step mechanism of the reaction. The activation energy (~2.7 $\text{kcal}\text{mol}$) and the encounter distance (~10.7 A) are only slightly larger than in the case of 2-aminopurine autoassociation, most probably because of a stronger solvation of thymidine molecules.     

Western blotting versus ELISA detection of stress proteins induced in the blue mussel Mytilus edulis exposed to cadmium and tributyltin

Stress proteins of the Hsp70 family induced in the blue mussel Mytilus edulis exposed in the laboratory to increased concentrations of cadmium (Cd) or tributhyltin (TBT) were analysed using Western blotting and/or ELISA tests. Statistical evaluation of results indicated that increased concentrations of Hsp70 were detected by means of the ELISA tests as compared with control organisms in extracts from the gills of mussels exposed to both Cd or TBT (p = 0.022). Results of analysis by means of Western blotting showed no differences in the levels of Hsp70 in the extracts (p = 0.151). It was concluded that the ELISA test allowed a more sensitive detection of Hsp70 than did Western blotting.     

Uranium and lead accumulation in cells of Streptomyces sp.

Lead and uranium were accumulated equally well both in the viable and dry biomass of Streptomyces sp. The process occurred in less than 5 min. Uranium was accumulated selectively from a polymetallic solution containing U, Pb, Cu, Zn, Ni, Co. The optimum pH for the process was 5.0, and the concentration of each metal in the solution was 10(-3) M. Under these conditions, the dry biomass of Streptomyces amounting to 1 mg/cm3 accumulated over 60% of the uranium in the solution. With the same amount of cell wall preparation it was possible to remove from the solution ca. 90% of U. In this case, the accumulated uranium reached 21% of the sorbent dry mass. Electron micrographs show that lead accumulated in Streptomyces cells is mainly concentrated in the cell wall structures although in the case of uranium this is not so clear.     

Effect of cefoperazone on the activity of selected parameters of cellular immunity in mice with experimental viral-bacterial infection

We applied mixed, viral-bacterial infections of mice (with influenza virus to the respiratory tract and Staphylococcus aureus) intereperitoneally. We used Sodium Cefoperazone subcutaneously in the dose of 30 mg/kg body weight 24, 48 and 72 hours after the infection. We evaluated phagocytic activity of the granulocytes isolated from animals and bactericidal activity of these cells expressed as their chemiluminescent activity. We studied it on the 3rd, 6th, 9th, and the 14th day after the infection. Phagocytic activity of cells taken from infected mice and treated with the preparation expressed as phagocytic index was the following: 0.38, 0.19; 0.88; 0.99 respectively. In the comparative studies, concerning the effect of preincubation of cells with antibiotic (at the concentration produced in blood serum by therapeutic doses) we found the increase in chemiluminescent process by 57% on the average. Analyzing the preliminary data form the experimental studies on the influence of Cefoperazone on mixed, viral-bacterial infections in mice we found the positive effect of the antibiotic evaluated in some immunological test. Intracellular killing of bacteria is stimulated. Preincubation of granulocytes with the antibiotic gives higher chemiluminescent activity of cells. However, chemotactic and phagocytic activity of cells are not changed.