Phytosociological characteristics of theRondeletio correifoliae-Andropogonetum multinervosi ass. nova (Sierra de la Siguanea,Isla de la Juventud,Cuba)

The contribution deals with the phytocenological analysis of theRondeletio correifoliae-Andropogonetum multinervosi, an endemic savanna association occuring on the Siguanea Hills (Sierra de la Siguanea) near the Colony Hotel.     

Preliminary classification and ecology of dry grassland communities on Ölands Stora Alvar (Sweden)

Four plant community types are described for Öland's Stora Alvar, the limestone plateau of South Öland and preliminary classified syntaxonomically:
(1) Crepis pumila – Allium alvarense ass. (2) Helianthemum oelandicum – Galium oelandicum ass. (3) Gypsophila fastigiata – Globularia vulgaris ass. and (4) Veronica spicata – Avenula pratensis ass. (with two subassociations, the Sedum reflexum and Galium boreale subass.). The ecology of these types is discussed with emphasis on soil depth, frost perturbation and the combined effects of summer drought and grazing intensity.
Various endemic taxa appear to be good character species for the community types described. The typical local ecology of some common species is discussed with the suggestion that they might have formed endemic ecotypes which should be further investigated.
The communities described are very rich in cryptogams. The floristic variation as expressed by the cryptogamic species composition shows largely the same pattern as that shown by the phanerogams.     

Streptomyces rimosus extracellular proteases 3. Isolation and characterization of leucine aminopeptidase

Summary A leucine aminopeptidase was purified to homogeneity fromStreptomyces rimosus culture filtrates, which are waste broth of oxytetracycline bioproduction process. Purification procedure includes ultrafiltration and chromatography on CM-Sephadex, AH-Sepharose and FPLC Mono S column. The enzyme is a monomer with molecular weight of 27,500 Daltons and pI of 7.3, stable in broad pH range and up to 70°C. It is a metallo enzyme dependent on Ca²⁺ ions for its full activity. By its specificity it is a true aminopeptidase active on amino acid amide, arylamide, peptide and ester bonds. The hydrolysing activity shows preference for leucine at the N-terminal position of substrates, also acts on aromatic acids and methionine, but does not release glycine, proline, acidic amino acids orD-amino acid residues.     

Effect of the polysaccharide ofAgrobacterium radiobacter on the growth of plants and occurrence of damping-off in sugar beet

Agrobacterium radiobacter, strain B6 (a strain isolated in this laboratory, which limited the occurrence of damping-off of sugar beet and influenced growth of plants in hot-house and field experiments) was found to produce an acidic exopolysaccharide in a mineral medium with various carbon sources. Hydrolyzates of the polysaccharide contained glucose, galactose, glycerol, succinic acid and pyruvic acid, whose quantitative content varied according to the carbon source used. The polysaccharide isolated from the medium containing glucose exhibited the highest physiological activity. Seeds germinated best and sugar beet roots were found to grow most rapidly in a medium containing 0.2 % (W/W) of the polysaccharide. The roots exposed for 3 d in this medium grew 2.7-fold as compared with non-treated plants. Higher sumbers of microorganisms were detected on the surface of roots treated with the polysaccharide. Growth of roots was also stimulated when immersing the seeds (30 min) in a 0.2 –0.4 % solution of this polysaccharide. After a two-fold treatment the roots were less damaged by the fungusPythium ultimum. Plants from seeds treated with the polysaccharide grew in the field soil more rapidly than the non-treated plants but worse than after bacterization of the seeds byA. radiobacter B6 and were only partially protected against the damping-off of sugar beet.     

Modification of Oudin’s method of single immunodiffusion in agar gel for detection of IgA in bronchoalveolar lavage of white mice

Oudin’s principle of single immunodiffusion in agar gel was modified for quantitative determination of IgA in bronchoalveolar lavage (BAL) of normal 20–25 g mice. The reaction took place at 25 °C in 0.3 % agarose with 16.7 % pig serum against mouse IgA, and was evaluated on the basis of a relationship between the progress of the precipitin zone and the square root of time. The linear dependence of the derived constantk on the logarithmic concentration of antibody in the sample permitted to express the results as titre, corresponding to a dilution wherek = 0. Examination of seven samples of pooled blood serum of normal mice shoved taht (1) the IgA level was practically constant, (2) serum IgA possessed under given conditions similar properties as IgA from the bronchoalveolar secretion; it is therefore possible to employ pooled sera as a reliable control of the immunodiffusion system in ease of lack of reference standards with defined IgA content. Examination of 82 individual BAL samples of normal mice revealed that the mean IgA concentration in 2.5 mL samples was almost 1000 times lower than in blood serum.     

Cholinesterase activity in some species of theAllium genus

In partly purified protein complexes obtained from 22 species of theAllium genus and 6 cultivars ofAllium cepa the activity of cholinesterases was detected and measured using the method of Ellman et al. The degree of its inhibition with 10^-4 M neostigmine was also tested. It was found that the activity of cholinesterase differed in individual species up to two hundred times, while the differences in the inhibitory activity of 10^-4 M neostigmine occurred only in a few cases. Individual sections and cultivars could not be characterized on the basis of the differences in the activities of the cholinesterases. Of all the sections that ofPhyllodolon shows the highest average activity. In the case of the tested cultivars distinctly the lowest activity was observed in cv. Kastická. The values of the enzymatic activity measured by Ellman’s method in this plant material include the activity of specific and unspecific cholinesterases and the part uninhibitable by neostigmine.