On the Suitability of Estelle for Multimedia Systems

Formal Description Techniques have been widely used for the specification of traditional networked applications. They have not been applied to the specification of new applications such as multimedia systems yet. In this paper, we examine the FDT Estelle with respect to its suitability for multimedia system specification and automatic derivation of efficient implementations. We show that it is possible to specify certain aspects of multimedia systems, but that Estelle is not sufficient for others. The derived implementations often perform badly. We show the reasons and propose to use a slightly modified Estelle syntax and semantics to solve the problems. The implemented solution was tested successfully

Constitutive expression of bergaptol O-methyltransferase in Glehnia littoralis cell cultures.

We investigated whether exogenously supplied precursors of bergapten, namely umbelliferone, psoralen and bergaptol, could be utilized to produce bergapten without elicitation in Glehnia littoralis cell suspension cultures. The levels of added psoralen and bergaptol in the medium soon decreased, and this was followed by the detection of bergapten in both culture fluid and cells. Umbelliferone was also incorporated but in this case no bergapten was produced; instead, skimmin, umbelliferone monoglucoside, was detected. To determine whether conversion of psoralen to bergapten was due to enzyme induction by precursor feeding, the transcript accumulations and enzyme activities of bergaptol O-methyltransferase (BMT, EC 2.1.1.69), which catalyzes the last step of bergapten synthesis, and of phenylalanine ammonia-lyase (PAL, EC 4.3.1.5), which catalyzes the initial step of the phenylpropanoid biosynthetic pathway and is known as a marker enzyme of elicitation, were examined. The results showed that both the expression and the activity of BMT were always detected in all cells, including control cells. Since PAL was slightly induced in the cells supplied with/without precursors, phenylethyl alcohol (PEA, a competitive inhibitor of PAL) was applied to suspension cells prior to the addition of psoralen. PAL activity was effectively inhibited by PEA at 1-5 mM concentrations. Under these conditions, PEA did not affect bergapten production by cell cultures fed with psoralen at all. These results demonstrate that BMT is constitutively expressed in G. littoralis cell cultures

Existing and emerging cyanocidal compounds: new perspectives for cyanobacterial bloom mitigation

To help ban the use of general toxic algicides, research efforts are now directed towards the discovery of compounds that are specifically acting as cyanocides. Here, we review the past and look forward into the future, where the less desirable general algicides like copper sulphate, diuron or endothall may become replaced by compounds that show better specificity for cyanobacteria and are biodegradable or transform into non-toxic products after application. For a range of products, we review the activity, the mode of action, effectiveness, durability, toxicity towards non-target species, plus costs involved, and discuss the experience with and prospects for small water volume interventions up to the mitigation of entire lakes; we arrive at recommendations for a series of natural products and extracted organic compounds or derived synthetic homologues with promising cyanocidal properties, and briefly mention emerging nanoparticle applications. Finally, we detail on the recently introduced application of hydrogen peroxide for the selective killing of cyanobacteria in freshwater lakes