Changes in the biological activity of agropyrene on combined application with humus substances in the cultivation ofScenedesmus obliquus (TURP.) krüger

The work is concerned with the question of the effect of humic acids on the biological action of agropyrene, the effective substance from the rootstock of Agropyron repens (L.) P. BEAUV. The test organism was the alga Scenedesmus obliquus (TURP.) KRÜGER, cultivated in mineral solution. The basic biological test was the determination of the number and size of the cells of this alga. It was found that the way in which agropyrene acts on combined application with humus acids depends on which humus fraction is used. It can display a synergic action if humic acid is used, since this substance probably facilitates the penetration of agropyrene into the cells. On the other hand, fulvic acid counteracts the activity of agropyrene and this most probably by mutual binding and blocking of active groups and links.     

Die durch Blattdüngung mit Humusstoffen hervorgerufenen anatomischen und physiologischen Veränderungen der Zuckerrübe

V p?edlo?ené práci je sledován ú?inek humusových látek aplikovaných na listy cukrovky post?ikem. Sou?asně je ově?ována vhodnost kombinace humusových látek s minerálními ?ivinami. Ukazuje se, ?e post?ik humusovými látkami zvlá?tě v kombinaci s minerálními ?ivinami p?íznivě ovlivňuje r?st cukrovky, zvy?uje váhu list? i ko?ene a celkové mno?ství cukru v ko?eni. Ú?inok post?iku humusovými látkami je vět?í u rostlin pěstovaných ve vodní kultu?e a st?íkaných ?ivným roztokem s kompletněj?ím zastoupením minerálních prvk?. Humusové látky p?i aplikaci na list vyvolávají podobné změny v anatomické stavbě pletiv a orgán?, jako p?i jejich aplikaci do ?ivného roztoku ke ko?en?m. Humusové látky zvlá?tě v kombinaci s minerálním roztokem zvy?ují v listech cukrovky mno?ství chlorofylu a zvy?ují intezitu fotosyntézy. Post?ik humusovými látkami zvy?uje sou?asně transpiraci cukrovky.     

Euglena gracilis as a supplementary test organism for detecting biologically active compounds

The mutagenic activity of more than 120 antimicrobial agents and protective components was investigated. Only Kathon showed a consistent increase in revertant counts in the Ames test onSalmonella typhimurium. The hereditary bleaching test onEuglena gracilis used for detecting extranuclear mutations, showed positive results for Kathon, triethanolamine and diamine silver tetraborate.     

The biology of Butomus umbellatus in shallow waters with fluctuating water level

Butomus umbellatus L. is a plant species typical of littoral communities of river and stream shores. It can form continuous stands in shallow reservoirs with fluctuating water level. Their expansion is promoted by: (a) intensive vegetative reproduction of plants, (b) crowded sprouting from rhizome fragments on emerged pond bottom, (c) shallow water layer in the year following summer drainage. Expansion of B. umbellatus depends on ploidy level: two cytotypes were found in the Czech and Slovak Republics, differing in their reproductive ability. Seed production of triploids is strongly limited (they are self-incompatible within clones), while diploids can be fully fertile. Nevertheless, even in diploids, the efficiency of seed reproduction under natural conditions is low. Triploids spread by intensive vegetative reproduction, which is decisive for clonal growth of populations and their regeneration after scraping of bottom surface. During seasonal development, maximum of aboveground biomass is produced in early summer, while underground biomass increases till autumn. Growth of the plants is limited by cutting before maximum underground biomass is attained, or by duck grazing.     

Growth response of Bolboschoenus maritimus ssp. maritimus and B. maritimus ssp. compactus to different trophic conditions

Bolboschoenus maritimus (L.) Palla (=Scirpus maritimus L.) forms extensive stands in the littoral zone of small fishponds and as a weed in rice and maize fields. Within the species, two subspecies are distinguished: Bolboschoenus maritimus subsp. maritimus, B. maritimus subsp. compactus. They differ in ecology, especially in their relationships with trophic conditions and salinity of habitats. To determine growth response of these two types to different nutrient levels, we compared their seasonal development under experimental cultivation at four controlled nutrient levels. Some differences between the subspecies were found to be stable, regardless of nutrient level, namely greater amount of smaller underground tubers and more extensive rhizome system in subsp. compactus compared to less numerous larger tubers and simpler rhizome system in subsp. maritimus. In response to trophic conditions,the plants of subsp. compactus were more resistant to the conditions of the highest trophic level than those of subsp. maritimus, which were stressed. This demonstrates better adaptability and spreading ability of B. maritimus subsp. compactus at high trophic levels.     

Partial auxin deprivation affects endogenous cytokinins in an auxin-dependent,cytokinin-independent tobacco cell strain

The dynamics of individual endogenous cytokinins within the growth cycle (subculture interval) of an auxin-dependent and cytokinin-independent cell suspension culture ofNicotiana tabacum L. (strain VBI-0) were determined using high performance liquid chromatography and radioimmunoassay. In cells grown at an optimum auxin concentration the transient maxima of N⁶-(²-isopentenyl)adenine and N⁶-(²-isopentenyl)-adenosine correlated with the onset of cell division. Cultivation of the cells in a partially auxin-deprived medium resulted in ca. tenfold increase of all endogenous cytokinins. A very distinct maximum of N⁶-(²-sopentenyl) adenine appeared at the beginning of subculture. This indicates that a lack of auxin induced an accumulation of cytokinins predominantly in the form of the free bases, which are physiologically more active than the corresponding ribosides.Abbreviations iP N⁶-(²-isopentenyl)adenine - [9R]iP N⁶-(²-isopentenyl)adenosine - t-Z trans-zeatin - t-[9R]Z trans-zeatin riboside - IAA indole-3-acetic acid - NAA 1-naphthaleneacetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - f.w. fresh weight - SBI subculture interval - C complete medium - PAD partially auxin-deprived medium - RP-HPLC reverse phase high performance liquid chromatography - RIA radioimmunoassay - PAL L-phenylalanine ammonia lyase     

Influence of 2,4-d and lactose on pollen embryogenesis in anther culture of potato

Anthers of diploid genotypes of Solanum tuberosum capable of androgenesis were cultured on different media to examine the effect on induction of pollen embryogenesis of 2,4-d and lactose. Anthers cultured in callogenic medium with 2,4-d and sucrose produced pollen derived embryoids only exceptionally. When sucrose was replaced by lactose the frequency of embryogenesis was as high or higher than in embryogenic auxin-free medium. Substitution of lactose for sucrose in the embryogenic medium had no effect. Supplementing the embryogenic medium with 2,4-d strongly reduced the frequency of pollen embryoids in the presence of sucrose but not with lactose.Abbreviations 2,4-d 2,4-dichlorophenoxyacetic acid     

Restriction endonucleases from Selenomonas ruminantium which recognize and cleave 5′-AT/TAAT-3′

Two natural isolates from fallow-deer rumen identified as Selenomonas ruminantium were found to produce a restriction endonuclease which we called Sru4DI. This enzyme was isolated from cell extracts by phosphocellulose chromatography. Analysis of the Sru4DI recognition site showed that Sru4DI recognizes the hexanucleotide sequence 5-AT/TAAT-3 generating 5 dinucleotide protruding ends upon cleavage and thus is a true isoschizomer of VspI, a restriction enzyme isolated from Vibrio sp.