Transfer of the broad-host-range IncQ plasmid RSF1010 and other plasmid vectors to the Gram-positive methylotroph Brevibacterium methylicum by electrotransformation

Gram-positive facultative methylotrophic coryneform bacterium Brevibacterium methylicum was efficiently transformed with various plasmids using electroporation of intact cells. In addition to the plasmid vectors pEC71 and pZ6-1 constructed on the basis of cryptic plasmids from coryneform bacteria, broad-host-range plasmids pLS5 (derivative of plasmid pMV158 from Streptococcus agalactiae) and RSF1010 belonging to the incompatibility group IncQ from Gram-negative bacteria were found to be present as autonomous structurally unchanged DNA molecules in B. methylicum transformants. With the exception of pZ6-1, all these plasmids were stably maintained in B. methylicum cells grown under non-selective conditions. When plasmid DNAs isolated from B. methylicum were used, the highest efficiency of transformation (10⁵ transformants/g DNA) was achieved. Correspondence to: J. Nevera     

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     

Inhibitory effect of lignin by-products of pulping on yeast growth

The antimicrobial properties of lignin by-products obtained by organic solvent, neutral sulfite semichemical and kraft pulping were shown in a series of yeasts. Lignin can act as an inhibitor of growth ofSporobolomyces roseus, Candida tropicalis, Trichosporon cutaneum andCandida albicans. Oxidation of all lignin samples tested depresses their inhibitory effects.     

Application of the exploratory data analysis for evaluating the toxicity of chlorinated phenol derivatives by various cell models

Exploratory data analysis based on multivariate statistical analysis techniques was introduced as a new approach to expressing the toxicity of chemical substances at the simultaneous acceptance of various cell models. Using principal component analysis and cluster analysis methods the toxicity of chlorinated phenol derivatives on employing some of the cell models (chlorococcal algae, cyanobacteria, bacteria, micromycetes, plant and animal cells) was characterized. The previous empirical experience that the toxicity of chlorinated phenol derivatives will increase with a growing degree of chlorination and that the presence of the methoxy group will cause a lowering of the toxic effect was demonstrated. The relationship between groups of tests used was presented.     

Changes in abundance of water birds species in southern Bohemia (Czech Republic) in the last 10 years

In 1981–1992, the breeding fauna of 153 fishponds was studies in three fishpond regions in south Bohemia (Czechoslovakia). On each pond, all water and wetland birds were censused by the Two-check method, which consists of adult birds counts during each breeding season (the first in the second part of May, and the second in the second part of June). We assessed the numbers of all species living in water and wetland habitats in the breeding season.The decline in abundances (expressed as number of individuals) of ducks (Anatinae), grebes (Podicipediformes), Coot (Fulica atra), Moorhen (Galinulla chloropus), Black-headed Gull (Larus ridibundus) were the most marked changes recorded. Marked increase in abundances was found in Cormorant (Phalacrocorax carbo) and Mute Swan (Cygnus olor) during the whole decade, whereas in Graylag Goose (Anser anser) the increase was restricted to the first half of the period under study. Numbers of charadriform and passeriform birds fluctuated in the dependence of water level variation.     

Effect of oxygen on ubiquinone-10 production by Paracoccus denitrificans

Summary Ubiquinone-10 (Q₁₀) production was measured in batch cultures of Paracoccus denitrificans grown for 8 h at increasing oxygen concentrations (0–21 % O₂ in the sparging gas). Whereas the cellular level of Q₁₀ decreased monotonically from 1.2 to 0.5 mol/g d.w., the total yield of Q₁₀ was maximal at 2.5 % O₂ and amounted to 350 nmol (0.3 mg) per L of culture.     

Some floristic and ecological characteristics of association Bromo-Plantaginetum mediae Ht. (31)49 on permanent plot No. 82 (National Park Plitvice Lakes — Croatia)

Plot 82 is one of a hundred permanent plots that have been set up in Croatia for the purpose of long-term and continual investigations of ecosystems and their successions. It is located in the area of Karleuine Plase within the Plitvice Lakes National Park. Vegetation on the plot belongs to association Bromo-Plantaginetum mediae. The association develops in mountainous regions of continental Croatia within a wide altitude range, from 180–1300 m a.s.l. on shallow soil over pervious carbonate rocks. The floristic composition and phytocoenological characteristics of the association have been analyzed using the common methods of the phytocoenological school Zürich-Montpellier, on the basis of 17 phytocoenological records. In addition to floristic composition, some site characteristics have been analysed: soil moisture, calcium carbonate, phosphates, pH value, humus, cation exchange capacity and nitrogen mineralization on the site and in the laboratory. The results obtained are comparable with the data presented in the available phytocoenological and ecological literature.     

The effect of submergence on tuber production and dormancy in two subspecies ofBolboschoenus maritimus

Two subspecies ofBolboschoenus maritimus (L.)Palla were cultivated in submerged and non-submerged conditions. The production of tubers, the proportion of tubers remaining dormant and the time between production and reactivation were investigated. Total tuber production was found to be dependent on subspecies and may be considered a biological character of the subspecies.Bolboschoenus maritimus ssp.compactus, a subspecies of less, flooded habitats, produced more tubers with a greater capacity for growth leaving a smaller proportion of dormant tubers. Inactivity of tubers and their reactivation after one or two years were enhanced by submergence in both subspecies. The proportion of tubers that are permanently dormant as well as the dormancy of the whole plant are important features influencing the survival of populations ofB. maritimus over periods of unfavourable conditions.