Effect of the new fluorescent brightener Rylux BSU on morphology and biosynthesis of cell walls in Saccharomyces cerevisiae

Rylux BSU, a new fluorescent brightener from the family of 4,4-diaminostilbene-2,2disulfonic acid derivatives, inhibited growth and cytokinesis of the yeast Saccharomyces cerevisiae. In the presence of 0.1–1 mg/ml Rylux BSU the cells grew in clumps, had irregular shape and were larger than controls. They formed apparently normal primary septa but their secondary septa and lateral cell walls, especially those in older cells, were abnormally thick with large deposits of amorphous wall material in the periplasmic spaces all over the cell surface. Chitin content in the cell walls of cells grown in the presence of Rylux BSU was increased 2 to 5 times in comparison to that of the controls and glucan content was reduced by up to 30%. In the in vitro assays with particulate membrane fractions, Rylux BSU acted as a non-competitive inhibitor of -1,3-glucan synthase with inhibitory constant K _i=1.75 mg/ml whereas the chitin synthase was inhibited to a much lesser extent. From the difference of the effects of Rylux BSU on the synthesis of chitin in vivo and in vitro it is concluded that the brightener interacts with chitin synthase only indirectly, possibly by influencing the properties of integral plasma membrane.Abbreviations RBSU Rylux BSU, 1,4-benzenedisulfonic acid-2,2-[ethyleneidy]bis[(3-sulpho-4,1-phenylene)imino[6-bis(2-hydroxyethyl)amino]-1,3,5-triazine-4,2-diylamino]]bis-, hexasodium salt - FB fluorescent brightener     

Cleavage polyembryonyin vivo andin vitro

The development of cleavage polyembryos of wheat, maize and radishin vivo andin vitro was compared. Some frequent features (such as common suspensors or suspensor-like structures, “concrescences”, enlarged radicular meristems) suggest a similar origin of cleavage polyembryos inducedin vivo and those inducedin vitro from the proembryo. Cleavage of the original zygotic or somatic proembryo may occur either at a few-celled stage or later in the phase of radicular meristem establishment.     

Comparison of twoPisum sativum nodulation mutants with their parental cultivar

In comparison with the parental cv. Finale the ‘RisfixC’ supernodulator exhibited higher, continuously increasing nodule number and fresh mass accumulation, but substantially lower individual nodule fresh mass, leghemoglobin concentration, and specific acetylene reduction activity of nodule tissue. There were no substantial differences between Finale and ‘RisfixC’ in total acetylene reduction, nodule leghemoglobin accumulation per nodulated root, total and specific CO₂ evolution from nodulated roots and gross CO₂ respiratory costs of acetylene reduction. The ‘RisfixC’ also exhibited a substantially lower plant dry mass production (by 30%), but nitrogen concentration in shoots and carotenoid concentration in leaf tissue were significantly higher by 33 and 14%, and the chlorophylla+b content insignficantly higher than in the parental cultivar. In contrast, the nodulation mutant ‘Risnod29’, exhibited a somewhat higher nodule fresh mass accumulation (by 21%) and individual nodule fresh mass (by 23%), total and specific acetylene reduction (by 49 and 19%) and a somewhat more rapid plant dry mass accumulation compared with the cv. Finale.     

Interrelationships between vesicular-arbuscular mycorrhiza and rhizosphere microflora in apple replant disease

Phytotoxic micromycetes appear to be responsible for the apple replant disease (ARD). This was suppressed by the inoculation of apple-tree seedlings with some species of vesicular-arbuscular mycorrhizal (VAM) fungi—Glomus fasciculatum andG. macrocarpum. After the inoculation, growth of apple-tree seedlings improved in dependence on the type of soil, on VAM fungus species and on the ARD appearance. After 12-month cultivation, plant biomass (height, shoot and root dry masses) was markedly increased by inoculation withG. fasciculatum. Similarly, the numbers of colony forming units per unit soil (CFU) of phytotoxic micromycetes and of diazotroph bacteria (associative dinitrogen-fixing bacteria) in the rhizosphere was affected; CFU of phytotoxic micromycetes decreased, whereas CFU of the genusAzospirillum was higher. These bacteria could also serve as antagonists against phytotoxic micromycetes. It is also suggested that the ratio of CFU of diazotroph bacteria to CFU of phytotoxic micromycetes can be used as an indicator of the degree of ARD. It may be assumed that the use of some VAM fungi can replace the chemcial treatment of the soil with ARD.     

Correlation between physico-chemical properties of quaternary ammonium salts of heptacaine and their inhibitory activity against photosynthesizing organisms

Photosynthesis inhibition in algae (Chlorella) and plant (spinach) chloroplasts by quaternary ammonium salts of heptacaine {N-[2-(2-heptyloxyphenylcarbamoyloxy)-ethyl]-N-alkylpiperidinium bromides} depended on the alkyl chain length of the alkyl substituent and showed good correlations with theoretical hydrophobic fragment constants as well as with experimentally determined physico-chemical parameters, namely extraction constants and surface activities. Communicated by. Z. ŠESTáK     

The influence of pH on growth kinetics of yeasts in the presence of benzoate as a sole carbon source

The inhibitory effect and substrate properties of benzoic acid were estimated for 25 yeast strains belonging to generaCondida, Hansenula, Hypopichia, Rhodosporidium, Rhodotorula, Saitoella andTrichosporon. Benzoic acid can serve as a sole carbon source for growth of yeasts belong to generaRhodotorula, Rhodosporidium andSaitoella in synthetic mineral media. Specific growth rate is strongly dependent both on the concentration of benzoate and the pH value of the cultivation media. Maximum specific growth rate on benzoate is observed in alkaline cultivation media at pH 7.0–7.5 whereas those for growth on glucose in mildly acidic media at pH 5.0. Some of the strains showed weak growth on benzoate even at pH 8.5. Some carotenoid-containing yeasts of the generaRhodotorula andRhodosporidium lost their ability to synthesize carotenoid pigments during growth in alkaline benzoate media.     

A new phage typing scheme forProteus mirabilis andProteus vulgaris strains

A new bacteriophage typing set, composed of 22 phages, was established as a tool for differentiation ofProteus strains. All the phages were tailed and included 4 morphological types (A1, A2, B1 and C1). They were classified into the familiesMyoviridae, Siphoviridae andPodoviridae. From the set, 19 phages had double-stranded DNA and 3 were single-stranded DNA phages.     

Poly(3-hydroxybutyrate) granules ofBacillus megaterium

Cells ofBacillus megaterium contain 35–45% of poly(3-hydroxybutyrate) (PHB) at the beginning of the stationary phase. This amount is only slightly affected by the medium composition. The PHB granules are spherical with the mean diameter of 1.15 μm.     

Effect of nitrogen concentration on the activity of manganese peroxidase ofPhanerochœte chrysosporium

Manganese peroxidase as an extracellular enzyme is produced by the white rot fungusPhanerochœte chrysosporium under nutrient nitrogen or carbon limitation. The effect of nitrogen concentration on the activity of manganese peroxidase was studied using ammonium nitrate andl-asparagine as nitrogen sources. The highest activity of the enzyme was observed in cultures grown in a medium containing 75 mg/L ammonium nitrate and 0.15 g/Ll-asparagine. Manganese peroxidase was not detectable in cultures grown in the presence 0.5 g/L ammonium nitrate and 1 g/Ll-asparagine.