Littoral diatoms as indicators for the eutrophication of shallow lakes

The littoral zone of shallow water bodies in the Czech Republic has been studied quite consistently at several fishponds. The use of algae, especially diatoms, for the monitoring of the state of lotic freshwater also has a long tradition. The main objective of the presented paper is to validate the feasibility of the use of littoral periphyton comunities for the biomonitoring of standing waters. At the investigated sites, littoral periphytic diatoms were studied together with selected enviromental variables (pH, conductivity, nutrients – especially total phosphorus) on three types of natural substrates (epilithon, epiphyton, epipelon). The evaluation of the diatom community was performed on the basis of the checklists of algal indicator species published by authors from the Czech Republic, Austria and the Netherlands. The data were subjected to statistical software NCCS 2000 (GLM Anova and ``Ward's minimum'' variance cluster analysis). Littoral periphytic diatoms appear to be good indicators of the fishpond water quality. The selected substrates show non-significant differences therefore the average values from all substrates were used. The best indicatory system for evaluation of Czech fishponds was van Dam's index.

     

Seasonal history ofTyphlodromus pyri (Acari: Mesostigmata: Phytoseiidae) in a commercial apple orchard in Czechoslovakia

The seasonal history and phenology of an indigenous field population ofTyphlodromus pyri Scheuten inhabiting a commercial apple orchard in South Bohemia are described. Data on population dynamics, number of generations, feeding, mating and reproductive habits as well as seasonal distribution within the apple tree canopy are discussed. Recommendations for mass retrieval ofT. pyri from apple orchards, their transfer to, and release in other orchards, are given. The conclusions and recommendations can be used for improving integrated pest management strategies in commercial apple orchards.     

Compounds isolated at theDepartment of Biogenesis of Natural Substances,institute of microbiology,Czechoslovak academy of sciences,in 1984–1988

A total of 41 compounds studied at theDepartment of Biogenesis of Natural Substances between 1984 and 1988 are characterized and tabulated. They include natural, semisynthetic and synthetic compounds. 1st supplement to the paper Podojilet al. (1984).     

The use of different oils for the cultivation ofStreptomyces cinnamonensis

The addition of 2–4% oils to the synthetic fermentation medium used for the cultivation ofStreptomyces cinnamonensis increased the production of monensin three times on the average. When the amount of the added oil was lower than 2% and higher than 4% the production sharply decreased. The maximal production preceded the maximal consumption of individual fatty acids of the added oils, the content of oleic acid decreasing most pronouncedly.     

Influence of the soya meal fractions on gibberellic acid and gibberellin A production in submerse cultivation ofGibberella fujikuroi

The relationship of different soya meal components to gibberellin (GA) production was studied. Fluorometric assay confirmed that under the given fermentation conditions, only gibberellic acid (GA₃) was synthesized on medium containing corn steep. On substituting soya flour for corn steep, the same amount of GA₃ was produced and in addition gibberellin A (GA₁) was formed. The GA₃: GA₁ ratio was 1∶1. The course of fermentation in media containing the soya meal protein fraction (fraction I), the soya meal amino acid complex, the corn steep amino acid complex and individual amino acids (γ-aminobutyric acid or tryptophane) was the same as in the control medium containing soya meal. The soya meal fraction II, which is characterized by a high cellulose and carbohydrate content, raised GA production by 25% as compared with production in medium containling soya meal; it simultaneously stimulated GA₃ production, so that the final GA₃: GA₁ ratio was 4∶1.     

Production of rhodomycins inStreptomyces griseoruber 4620

The strainStreptomyces griseoruber 4620 produces, besides the anthracycline antibiotics beromycins, some other anthracyclines of the rhodomycin type. Twelve isolates exhibiting a higher antibiotic activity (up to 2.5×), as compared to the parent strain, were obtained after a spontaneous selection. The following species were isolated from the hydrolysate of mycelial extract: β-rhodomycinone, β-isorhodomycinone, α₂-rhodomycinone and 10-deoxy-β-rhodomycinone, which has not yet been described.     

The genusMicromeles revisited

Micromeles Decaisne emend.Koehne (Rosaceae, Maloideae) is shown to be generically distinct fromSorbus L. emend.Crantz. Problems in the taxonomy of the genus are reviewed. The genus appears to be most closely related toRaphiolepis Lindl. but is readily distinguished by a constant set of characters. Both genera may be derived fromSorbus L. emend.Crantz subg.Aria Pers. Analysis of morphological characters is provided. A survey for flavonoids revealed the presence of vitexin and/or luteolin 7-O-glucoside in some members of the genus in a pattern similar to that found in certain Asian species ofSorbus. There are also brief taxonomic notes on some of the species which were examined.     

A 13c-n.m.r. study of 1,6:2,3- and 1,6:3,4-dianhydro-β-D-hexo-pyranoses and their O-acetyl and deoxy derivatives

¹³C-N.m.r. spectra of all possible 1,6:2,3- and 1,6:3,4-dianhydro-β-D-hexo-pyranoses and their O-acetyl and deoxy derivatives are presented. Relations between chemical shifts of certain carbon atoms and the structure of the dianhydrides are outlined, and their application in structural analysis is discussed. Inversion of configuration of the oxirane ring from the endo to the exo position is associated with typical upfield-shifts for oxirane-ring carbon atoms C-2 or C-4, respectively. Possible inter-relationships between ¹³C-chemical shifts and steric and polar interactions in the dianhydro derivatives are discussed.     

Eurotium (Aspergillus) repens metabolites and their biological activity

Eurotium repens mycelium cultivated under static conditions was used to isolate and identify metabolities—echinulin, physcion, erythroglaucin, flavoglaucin and asperentin; the filtrate of the culture yielded asperentin 8-methylether. The broadest biological activity spectrum was displayed by asperentin which had antibacterial and antifungal effects and, at a concentration of 86 ώg/ml, caused 50 % mor7 tality inArtemia saline larvae. The highest cytotoxicity towards HeLa cells was found in physcion which caused 50 % growth inhibition at a concentration of 0.1 ώg/ml.